From 4bf66948ee491c1cb0a4eda8f4e3d85547c24d2a Mon Sep 17 00:00:00 2001
From: Jacob Domagala <domagala.jacob@gmail.com>
Date: Wed, 20 Dec 2023 12:47:27 +0100
Subject: [PATCH] #2216: Rollback fmt version to 7.1.3 due to CUDA

---
 cmake_config.h.in                      |    2 -
 lib/fmt/CMakeLists.txt                 |    3 +-
 lib/fmt/include/fmt-vt/args.h          |  234 -
 lib/fmt/include/fmt-vt/chrono.h        | 2207 ---------
 lib/fmt/include/fmt-vt/color.h         |  633 ---
 lib/fmt/include/fmt-vt/compile.h       |  534 --
 lib/fmt/include/fmt-vt/core.h          | 3001 +++++-------
 lib/fmt/include/fmt-vt/format-inl.h    | 3666 +++++++++-----
 lib/fmt/include/fmt-vt/format.h        | 6272 +++++++++++-------------
 lib/fmt/include/fmt-vt/ostream.h       |  246 +-
 lib/fmt/include/fmt-vt/printf.h        |  675 ---
 lib/fmt/include/fmt-vt/ranges.h        |  731 ---
 lib/fmt/include/fmt-vt/std.h           |  498 --
 lib/fmt/include/fmt-vt/xchar.h         |  258 -
 lib/fmt/src/format.cc                  |   92 +-
 src/vt/topos/index/dense/dense_array.h |   11 +-
 16 files changed, 6507 insertions(+), 12556 deletions(-)
 delete mode 100644 lib/fmt/include/fmt-vt/args.h
 delete mode 100644 lib/fmt/include/fmt-vt/chrono.h
 delete mode 100644 lib/fmt/include/fmt-vt/color.h
 delete mode 100644 lib/fmt/include/fmt-vt/compile.h
 delete mode 100644 lib/fmt/include/fmt-vt/printf.h
 delete mode 100644 lib/fmt/include/fmt-vt/ranges.h
 delete mode 100644 lib/fmt/include/fmt-vt/std.h
 delete mode 100644 lib/fmt/include/fmt-vt/xchar.h

diff --git a/cmake_config.h.in b/cmake_config.h.in
index fdf9aa4e34..c10bea5e62 100644
--- a/cmake_config.h.in
+++ b/cmake_config.h.in
@@ -95,7 +95,6 @@
 #if vt_feature_cmake_external_fmt
   #define INCLUDE_FMT_CORE <fmt/core.h>
   #define INCLUDE_FMT_FORMAT <fmt/format.h>
-  #define INCLUDE_FMT_RANGES <fmt/ranges.h>
   #define INCLUDE_FMT_OSTREAM <fmt/ostream.h>
 
   #define VT_FMT_NAMESPACE_BEGIN namespace fmt {
@@ -103,7 +102,6 @@
 #else
   #define INCLUDE_FMT_CORE <fmt-vt/core.h>
   #define INCLUDE_FMT_FORMAT <fmt-vt/format.h>
-  #define INCLUDE_FMT_RANGES <fmt-vt/ranges.h>
   #define INCLUDE_FMT_OSTREAM <fmt-vt/ostream.h>
 
   #define VT_FMT_NAMESPACE_BEGIN namespace fmt { inline namespace vt {
diff --git a/lib/fmt/CMakeLists.txt b/lib/fmt/CMakeLists.txt
index 72669e69bc..0357be8374 100644
--- a/lib/fmt/CMakeLists.txt
+++ b/lib/fmt/CMakeLists.txt
@@ -9,8 +9,7 @@ function(add_headers VAR)
 endfunction()
 
 # Define the fmt library, its includes and the needed defines.
-add_headers(FMT_HEADERS args.h color.h core.h format-inl.h ostream.h ranges.h
-            xchar.h chrono.h compile.h format.h printf.h std.h)
+add_headers(FMT_HEADERS core.h format.h format-inl.h ostream.h)
 set(FMT_SOURCES src/format.cc)
 
 add_library(fmt ${FMT_SOURCES} ${FMT_HEADERS})
diff --git a/lib/fmt/include/fmt-vt/args.h b/lib/fmt/include/fmt-vt/args.h
deleted file mode 100644
index 2d684e7cc1..0000000000
--- a/lib/fmt/include/fmt-vt/args.h
+++ /dev/null
@@ -1,234 +0,0 @@
-// Formatting library for C++ - dynamic argument lists
-//
-// Copyright (c) 2012 - present, Victor Zverovich
-// All rights reserved.
-//
-// For the license information refer to format.h.
-
-#ifndef FMT_ARGS_H_
-#define FMT_ARGS_H_
-
-#include <functional>  // std::reference_wrapper
-#include <memory>      // std::unique_ptr
-#include <vector>
-
-#include "core.h"
-
-FMT_BEGIN_NAMESPACE
-
-namespace detail {
-
-template <typename T> struct is_reference_wrapper : std::false_type {};
-template <typename T>
-struct is_reference_wrapper<std::reference_wrapper<T>> : std::true_type {};
-
-template <typename T> const T& unwrap(const T& v) { return v; }
-template <typename T> const T& unwrap(const std::reference_wrapper<T>& v) {
-  return static_cast<const T&>(v);
-}
-
-class dynamic_arg_list {
-  // Workaround for clang's -Wweak-vtables. Unlike for regular classes, for
-  // templates it doesn't complain about inability to deduce single translation
-  // unit for placing vtable. So storage_node_base is made a fake template.
-  template <typename = void> struct node {
-    virtual ~node() = default;
-    std::unique_ptr<node<>> next;
-  };
-
-  template <typename T> struct typed_node : node<> {
-    T value;
-
-    template <typename Arg>
-    FMT_CONSTEXPR typed_node(const Arg& arg) : value(arg) {}
-
-    template <typename Char>
-    FMT_CONSTEXPR typed_node(const basic_string_view<Char>& arg)
-        : value(arg.data(), arg.size()) {}
-  };
-
-  std::unique_ptr<node<>> head_;
-
- public:
-  template <typename T, typename Arg> const T& push(const Arg& arg) {
-    auto new_node = std::unique_ptr<typed_node<T>>(new typed_node<T>(arg));
-    auto& value = new_node->value;
-    new_node->next = std::move(head_);
-    head_ = std::move(new_node);
-    return value;
-  }
-};
-}  // namespace detail
-
-/**
-  \rst
-  A dynamic version of `fmt::format_arg_store`.
-  It's equipped with a storage to potentially temporary objects which lifetimes
-  could be shorter than the format arguments object.
-
-  It can be implicitly converted into `~fmt::basic_format_args` for passing
-  into type-erased formatting functions such as `~fmt::vformat`.
-  \endrst
- */
-template <typename Context>
-class dynamic_format_arg_store
-#if FMT_GCC_VERSION && FMT_GCC_VERSION < 409
-    // Workaround a GCC template argument substitution bug.
-    : public basic_format_args<Context>
-#endif
-{
- private:
-  using char_type = typename Context::char_type;
-
-  template <typename T> struct need_copy {
-    static constexpr detail::type mapped_type =
-        detail::mapped_type_constant<T, Context>::value;
-
-    enum {
-      value = !(detail::is_reference_wrapper<T>::value ||
-                std::is_same<T, basic_string_view<char_type>>::value ||
-                std::is_same<T, detail::std_string_view<char_type>>::value ||
-                (mapped_type != detail::type::cstring_type &&
-                 mapped_type != detail::type::string_type &&
-                 mapped_type != detail::type::custom_type))
-    };
-  };
-
-  template <typename T>
-  using stored_type = conditional_t<
-      std::is_convertible<T, std::basic_string<char_type>>::value &&
-          !detail::is_reference_wrapper<T>::value,
-      std::basic_string<char_type>, T>;
-
-  // Storage of basic_format_arg must be contiguous.
-  std::vector<basic_format_arg<Context>> data_;
-  std::vector<detail::named_arg_info<char_type>> named_info_;
-
-  // Storage of arguments not fitting into basic_format_arg must grow
-  // without relocation because items in data_ refer to it.
-  detail::dynamic_arg_list dynamic_args_;
-
-  friend class basic_format_args<Context>;
-
-  unsigned long long get_types() const {
-    return detail::is_unpacked_bit | data_.size() |
-           (named_info_.empty()
-                ? 0ULL
-                : static_cast<unsigned long long>(detail::has_named_args_bit));
-  }
-
-  const basic_format_arg<Context>* data() const {
-    return named_info_.empty() ? data_.data() : data_.data() + 1;
-  }
-
-  template <typename T> void emplace_arg(const T& arg) {
-    data_.emplace_back(detail::make_arg<Context>(arg));
-  }
-
-  template <typename T>
-  void emplace_arg(const detail::named_arg<char_type, T>& arg) {
-    if (named_info_.empty()) {
-      constexpr const detail::named_arg_info<char_type>* zero_ptr{nullptr};
-      data_.insert(data_.begin(), {zero_ptr, 0});
-    }
-    data_.emplace_back(detail::make_arg<Context>(detail::unwrap(arg.value)));
-    auto pop_one = [](std::vector<basic_format_arg<Context>>* data) {
-      data->pop_back();
-    };
-    std::unique_ptr<std::vector<basic_format_arg<Context>>, decltype(pop_one)>
-        guard{&data_, pop_one};
-    named_info_.push_back({arg.name, static_cast<int>(data_.size() - 2u)});
-    data_[0].value_.named_args = {named_info_.data(), named_info_.size()};
-    guard.release();
-  }
-
- public:
-  constexpr dynamic_format_arg_store() = default;
-
-  /**
-    \rst
-    Adds an argument into the dynamic store for later passing to a formatting
-    function.
-
-    Note that custom types and string types (but not string views) are copied
-    into the store dynamically allocating memory if necessary.
-
-    **Example**::
-
-      fmt::dynamic_format_arg_store<fmt::format_context> store;
-      store.push_back(42);
-      store.push_back("abc");
-      store.push_back(1.5f);
-      std::string result = fmt::vformat("{} and {} and {}", store);
-    \endrst
-  */
-  template <typename T> void push_back(const T& arg) {
-    if (detail::const_check(need_copy<T>::value))
-      emplace_arg(dynamic_args_.push<stored_type<T>>(arg));
-    else
-      emplace_arg(detail::unwrap(arg));
-  }
-
-  /**
-    \rst
-    Adds a reference to the argument into the dynamic store for later passing to
-    a formatting function.
-
-    **Example**::
-
-      fmt::dynamic_format_arg_store<fmt::format_context> store;
-      char band[] = "Rolling Stones";
-      store.push_back(std::cref(band));
-      band[9] = 'c'; // Changing str affects the output.
-      std::string result = fmt::vformat("{}", store);
-      // result == "Rolling Scones"
-    \endrst
-  */
-  template <typename T> void push_back(std::reference_wrapper<T> arg) {
-    static_assert(
-        need_copy<T>::value,
-        "objects of built-in types and string views are always copied");
-    emplace_arg(arg.get());
-  }
-
-  /**
-    Adds named argument into the dynamic store for later passing to a formatting
-    function. ``std::reference_wrapper`` is supported to avoid copying of the
-    argument. The name is always copied into the store.
-  */
-  template <typename T>
-  void push_back(const detail::named_arg<char_type, T>& arg) {
-    const char_type* arg_name =
-        dynamic_args_.push<std::basic_string<char_type>>(arg.name).c_str();
-    if (detail::const_check(need_copy<T>::value)) {
-      emplace_arg(
-          fmt::arg(arg_name, dynamic_args_.push<stored_type<T>>(arg.value)));
-    } else {
-      emplace_arg(fmt::arg(arg_name, arg.value));
-    }
-  }
-
-  /** Erase all elements from the store */
-  void clear() {
-    data_.clear();
-    named_info_.clear();
-    dynamic_args_ = detail::dynamic_arg_list();
-  }
-
-  /**
-    \rst
-    Reserves space to store at least *new_cap* arguments including
-    *new_cap_named* named arguments.
-    \endrst
-  */
-  void reserve(size_t new_cap, size_t new_cap_named) {
-    FMT_ASSERT(new_cap >= new_cap_named,
-               "Set of arguments includes set of named arguments");
-    data_.reserve(new_cap);
-    named_info_.reserve(new_cap_named);
-  }
-};
-
-FMT_END_NAMESPACE
-
-#endif  // FMT_ARGS_H_
diff --git a/lib/fmt/include/fmt-vt/chrono.h b/lib/fmt/include/fmt-vt/chrono.h
deleted file mode 100644
index 7bd4206d75..0000000000
--- a/lib/fmt/include/fmt-vt/chrono.h
+++ /dev/null
@@ -1,2207 +0,0 @@
-// Formatting library for C++ - chrono support
-//
-// Copyright (c) 2012 - present, Victor Zverovich
-// All rights reserved.
-//
-// For the license information refer to format.h.
-
-#ifndef FMT_CHRONO_H_
-#define FMT_CHRONO_H_
-
-#include <algorithm>
-#include <chrono>
-#include <cmath>    // std::isfinite
-#include <cstring>  // std::memcpy
-#include <ctime>
-#include <iterator>
-#include <locale>
-#include <ostream>
-#include <type_traits>
-
-#include "format.h"
-
-FMT_BEGIN_NAMESPACE
-
-// Check if std::chrono::local_t is available.
-#ifndef FMT_USE_LOCAL_TIME
-#  ifdef __cpp_lib_chrono
-#    define FMT_USE_LOCAL_TIME (__cpp_lib_chrono >= 201907L)
-#  else
-#    define FMT_USE_LOCAL_TIME 0
-#  endif
-#endif
-
-// Check if std::chrono::utc_timestamp is available.
-#ifndef FMT_USE_UTC_TIME
-#  ifdef __cpp_lib_chrono
-#    define FMT_USE_UTC_TIME (__cpp_lib_chrono >= 201907L)
-#  else
-#    define FMT_USE_UTC_TIME 0
-#  endif
-#endif
-
-// Enable tzset.
-#ifndef FMT_USE_TZSET
-// UWP doesn't provide _tzset.
-#  if FMT_HAS_INCLUDE("winapifamily.h")
-#    include <winapifamily.h>
-#  endif
-#  if defined(_WIN32) && (!defined(WINAPI_FAMILY) || \
-                          (WINAPI_FAMILY == WINAPI_FAMILY_DESKTOP_APP))
-#    define FMT_USE_TZSET 1
-#  else
-#    define FMT_USE_TZSET 0
-#  endif
-#endif
-
-// Enable safe chrono durations, unless explicitly disabled.
-#ifndef FMT_SAFE_DURATION_CAST
-#  define FMT_SAFE_DURATION_CAST 1
-#endif
-#if FMT_SAFE_DURATION_CAST
-
-// For conversion between std::chrono::durations without undefined
-// behaviour or erroneous results.
-// This is a stripped down version of duration_cast, for inclusion in fmt.
-// See https://github.com/pauldreik/safe_duration_cast
-//
-// Copyright Paul Dreik 2019
-namespace safe_duration_cast {
-
-template <typename To, typename From,
-          FMT_ENABLE_IF(!std::is_same<From, To>::value &&
-                        std::numeric_limits<From>::is_signed ==
-                            std::numeric_limits<To>::is_signed)>
-FMT_CONSTEXPR To lossless_integral_conversion(const From from, int& ec) {
-  ec = 0;
-  using F = std::numeric_limits<From>;
-  using T = std::numeric_limits<To>;
-  static_assert(F::is_integer, "From must be integral");
-  static_assert(T::is_integer, "To must be integral");
-
-  // A and B are both signed, or both unsigned.
-  if (detail::const_check(F::digits <= T::digits)) {
-    // From fits in To without any problem.
-  } else {
-    // From does not always fit in To, resort to a dynamic check.
-    if (from < (T::min)() || from > (T::max)()) {
-      // outside range.
-      ec = 1;
-      return {};
-    }
-  }
-  return static_cast<To>(from);
-}
-
-/**
- * converts From to To, without loss. If the dynamic value of from
- * can't be converted to To without loss, ec is set.
- */
-template <typename To, typename From,
-          FMT_ENABLE_IF(!std::is_same<From, To>::value &&
-                        std::numeric_limits<From>::is_signed !=
-                            std::numeric_limits<To>::is_signed)>
-FMT_CONSTEXPR To lossless_integral_conversion(const From from, int& ec) {
-  ec = 0;
-  using F = std::numeric_limits<From>;
-  using T = std::numeric_limits<To>;
-  static_assert(F::is_integer, "From must be integral");
-  static_assert(T::is_integer, "To must be integral");
-
-  if (detail::const_check(F::is_signed && !T::is_signed)) {
-    // From may be negative, not allowed!
-    if (fmt::detail::is_negative(from)) {
-      ec = 1;
-      return {};
-    }
-    // From is positive. Can it always fit in To?
-    if (detail::const_check(F::digits > T::digits) &&
-        from > static_cast<From>(detail::max_value<To>())) {
-      ec = 1;
-      return {};
-    }
-  }
-
-  if (detail::const_check(!F::is_signed && T::is_signed &&
-                          F::digits >= T::digits) &&
-      from > static_cast<From>(detail::max_value<To>())) {
-    ec = 1;
-    return {};
-  }
-  return static_cast<To>(from);  // Lossless conversion.
-}
-
-template <typename To, typename From,
-          FMT_ENABLE_IF(std::is_same<From, To>::value)>
-FMT_CONSTEXPR To lossless_integral_conversion(const From from, int& ec) {
-  ec = 0;
-  return from;
-}  // function
-
-// clang-format off
-/**
- * converts From to To if possible, otherwise ec is set.
- *
- * input                            |    output
- * ---------------------------------|---------------
- * NaN                              | NaN
- * Inf                              | Inf
- * normal, fits in output           | converted (possibly lossy)
- * normal, does not fit in output   | ec is set
- * subnormal                        | best effort
- * -Inf                             | -Inf
- */
-// clang-format on
-template <typename To, typename From,
-          FMT_ENABLE_IF(!std::is_same<From, To>::value)>
-FMT_CONSTEXPR To safe_float_conversion(const From from, int& ec) {
-  ec = 0;
-  using T = std::numeric_limits<To>;
-  static_assert(std::is_floating_point<From>::value, "From must be floating");
-  static_assert(std::is_floating_point<To>::value, "To must be floating");
-
-  // catch the only happy case
-  if (std::isfinite(from)) {
-    if (from >= T::lowest() && from <= (T::max)()) {
-      return static_cast<To>(from);
-    }
-    // not within range.
-    ec = 1;
-    return {};
-  }
-
-  // nan and inf will be preserved
-  return static_cast<To>(from);
-}  // function
-
-template <typename To, typename From,
-          FMT_ENABLE_IF(std::is_same<From, To>::value)>
-FMT_CONSTEXPR To safe_float_conversion(const From from, int& ec) {
-  ec = 0;
-  static_assert(std::is_floating_point<From>::value, "From must be floating");
-  return from;
-}
-
-/**
- * safe duration cast between integral durations
- */
-template <typename To, typename FromRep, typename FromPeriod,
-          FMT_ENABLE_IF(std::is_integral<FromRep>::value),
-          FMT_ENABLE_IF(std::is_integral<typename To::rep>::value)>
-To safe_duration_cast(std::chrono::duration<FromRep, FromPeriod> from,
-                      int& ec) {
-  using From = std::chrono::duration<FromRep, FromPeriod>;
-  ec = 0;
-  // the basic idea is that we need to convert from count() in the from type
-  // to count() in the To type, by multiplying it with this:
-  struct Factor
-      : std::ratio_divide<typename From::period, typename To::period> {};
-
-  static_assert(Factor::num > 0, "num must be positive");
-  static_assert(Factor::den > 0, "den must be positive");
-
-  // the conversion is like this: multiply from.count() with Factor::num
-  // /Factor::den and convert it to To::rep, all this without
-  // overflow/underflow. let's start by finding a suitable type that can hold
-  // both To, From and Factor::num
-  using IntermediateRep =
-      typename std::common_type<typename From::rep, typename To::rep,
-                                decltype(Factor::num)>::type;
-
-  // safe conversion to IntermediateRep
-  IntermediateRep count =
-      lossless_integral_conversion<IntermediateRep>(from.count(), ec);
-  if (ec) return {};
-  // multiply with Factor::num without overflow or underflow
-  if (detail::const_check(Factor::num != 1)) {
-    const auto max1 = detail::max_value<IntermediateRep>() / Factor::num;
-    if (count > max1) {
-      ec = 1;
-      return {};
-    }
-    const auto min1 =
-        (std::numeric_limits<IntermediateRep>::min)() / Factor::num;
-    if (detail::const_check(!std::is_unsigned<IntermediateRep>::value) &&
-        count < min1) {
-      ec = 1;
-      return {};
-    }
-    count *= Factor::num;
-  }
-
-  if (detail::const_check(Factor::den != 1)) count /= Factor::den;
-  auto tocount = lossless_integral_conversion<typename To::rep>(count, ec);
-  return ec ? To() : To(tocount);
-}
-
-/**
- * safe duration_cast between floating point durations
- */
-template <typename To, typename FromRep, typename FromPeriod,
-          FMT_ENABLE_IF(std::is_floating_point<FromRep>::value),
-          FMT_ENABLE_IF(std::is_floating_point<typename To::rep>::value)>
-To safe_duration_cast(std::chrono::duration<FromRep, FromPeriod> from,
-                      int& ec) {
-  using From = std::chrono::duration<FromRep, FromPeriod>;
-  ec = 0;
-  if (std::isnan(from.count())) {
-    // nan in, gives nan out. easy.
-    return To{std::numeric_limits<typename To::rep>::quiet_NaN()};
-  }
-  // maybe we should also check if from is denormal, and decide what to do about
-  // it.
-
-  // +-inf should be preserved.
-  if (std::isinf(from.count())) {
-    return To{from.count()};
-  }
-
-  // the basic idea is that we need to convert from count() in the from type
-  // to count() in the To type, by multiplying it with this:
-  struct Factor
-      : std::ratio_divide<typename From::period, typename To::period> {};
-
-  static_assert(Factor::num > 0, "num must be positive");
-  static_assert(Factor::den > 0, "den must be positive");
-
-  // the conversion is like this: multiply from.count() with Factor::num
-  // /Factor::den and convert it to To::rep, all this without
-  // overflow/underflow. let's start by finding a suitable type that can hold
-  // both To, From and Factor::num
-  using IntermediateRep =
-      typename std::common_type<typename From::rep, typename To::rep,
-                                decltype(Factor::num)>::type;
-
-  // force conversion of From::rep -> IntermediateRep to be safe,
-  // even if it will never happen be narrowing in this context.
-  IntermediateRep count =
-      safe_float_conversion<IntermediateRep>(from.count(), ec);
-  if (ec) {
-    return {};
-  }
-
-  // multiply with Factor::num without overflow or underflow
-  if (detail::const_check(Factor::num != 1)) {
-    constexpr auto max1 = detail::max_value<IntermediateRep>() /
-                          static_cast<IntermediateRep>(Factor::num);
-    if (count > max1) {
-      ec = 1;
-      return {};
-    }
-    constexpr auto min1 = std::numeric_limits<IntermediateRep>::lowest() /
-                          static_cast<IntermediateRep>(Factor::num);
-    if (count < min1) {
-      ec = 1;
-      return {};
-    }
-    count *= static_cast<IntermediateRep>(Factor::num);
-  }
-
-  // this can't go wrong, right? den>0 is checked earlier.
-  if (detail::const_check(Factor::den != 1)) {
-    using common_t = typename std::common_type<IntermediateRep, intmax_t>::type;
-    count /= static_cast<common_t>(Factor::den);
-  }
-
-  // convert to the to type, safely
-  using ToRep = typename To::rep;
-
-  const ToRep tocount = safe_float_conversion<ToRep>(count, ec);
-  if (ec) {
-    return {};
-  }
-  return To{tocount};
-}
-}  // namespace safe_duration_cast
-#endif
-
-// Prevents expansion of a preceding token as a function-style macro.
-// Usage: f FMT_NOMACRO()
-#define FMT_NOMACRO
-
-namespace detail {
-template <typename T = void> struct null {};
-inline null<> localtime_r FMT_NOMACRO(...) { return null<>(); }
-inline null<> localtime_s(...) { return null<>(); }
-inline null<> gmtime_r(...) { return null<>(); }
-inline null<> gmtime_s(...) { return null<>(); }
-
-inline const std::locale& get_classic_locale() {
-  static const auto& locale = std::locale::classic();
-  return locale;
-}
-
-template <typename CodeUnit> struct codecvt_result {
-  static constexpr const size_t max_size = 32;
-  CodeUnit buf[max_size];
-  CodeUnit* end;
-};
-
-template <typename CodeUnit>
-void write_codecvt(codecvt_result<CodeUnit>& out, string_view in_buf,
-                   const std::locale& loc) {
-#if FMT_CLANG_VERSION
-#  pragma clang diagnostic push
-#  pragma clang diagnostic ignored "-Wdeprecated"
-  auto& f = std::use_facet<std::codecvt<CodeUnit, char, std::mbstate_t>>(loc);
-#  pragma clang diagnostic pop
-#else
-  auto& f = std::use_facet<std::codecvt<CodeUnit, char, std::mbstate_t>>(loc);
-#endif
-  auto mb = std::mbstate_t();
-  const char* from_next = nullptr;
-  auto result = f.in(mb, in_buf.begin(), in_buf.end(), from_next,
-                     std::begin(out.buf), std::end(out.buf), out.end);
-  if (result != std::codecvt_base::ok)
-    FMT_THROW(format_error("failed to format time"));
-}
-
-template <typename OutputIt>
-auto write_encoded_tm_str(OutputIt out, string_view in, const std::locale& loc)
-    -> OutputIt {
-  if (detail::is_utf8() && loc != get_classic_locale()) {
-    // char16_t and char32_t codecvts are broken in MSVC (linkage errors) and
-    // gcc-4.
-#if FMT_MSC_VERSION != 0 || \
-    (defined(__GLIBCXX__) && !defined(_GLIBCXX_USE_DUAL_ABI))
-    // The _GLIBCXX_USE_DUAL_ABI macro is always defined in libstdc++ from gcc-5
-    // and newer.
-    using code_unit = wchar_t;
-#else
-    using code_unit = char32_t;
-#endif
-
-    using unit_t = codecvt_result<code_unit>;
-    unit_t unit;
-    write_codecvt(unit, in, loc);
-    // In UTF-8 is used one to four one-byte code units.
-    auto u =
-        to_utf8<code_unit, basic_memory_buffer<char, unit_t::max_size * 4>>();
-    if (!u.convert({unit.buf, to_unsigned(unit.end - unit.buf)}))
-      FMT_THROW(format_error("failed to format time"));
-    return copy_str<char>(u.c_str(), u.c_str() + u.size(), out);
-  }
-  return copy_str<char>(in.data(), in.data() + in.size(), out);
-}
-
-template <typename Char, typename OutputIt,
-          FMT_ENABLE_IF(!std::is_same<Char, char>::value)>
-auto write_tm_str(OutputIt out, string_view sv, const std::locale& loc)
-    -> OutputIt {
-  codecvt_result<Char> unit;
-  write_codecvt(unit, sv, loc);
-  return copy_str<Char>(unit.buf, unit.end, out);
-}
-
-template <typename Char, typename OutputIt,
-          FMT_ENABLE_IF(std::is_same<Char, char>::value)>
-auto write_tm_str(OutputIt out, string_view sv, const std::locale& loc)
-    -> OutputIt {
-  return write_encoded_tm_str(out, sv, loc);
-}
-
-template <typename Char>
-inline void do_write(buffer<Char>& buf, const std::tm& time,
-                     const std::locale& loc, char format, char modifier) {
-  auto&& format_buf = formatbuf<std::basic_streambuf<Char>>(buf);
-  auto&& os = std::basic_ostream<Char>(&format_buf);
-  os.imbue(loc);
-  using iterator = std::ostreambuf_iterator<Char>;
-  const auto& facet = std::use_facet<std::time_put<Char, iterator>>(loc);
-  auto end = facet.put(os, os, Char(' '), &time, format, modifier);
-  if (end.failed()) FMT_THROW(format_error("failed to format time"));
-}
-
-template <typename Char, typename OutputIt,
-          FMT_ENABLE_IF(!std::is_same<Char, char>::value)>
-auto write(OutputIt out, const std::tm& time, const std::locale& loc,
-           char format, char modifier = 0) -> OutputIt {
-  auto&& buf = get_buffer<Char>(out);
-  do_write<Char>(buf, time, loc, format, modifier);
-  return get_iterator(buf, out);
-}
-
-template <typename Char, typename OutputIt,
-          FMT_ENABLE_IF(std::is_same<Char, char>::value)>
-auto write(OutputIt out, const std::tm& time, const std::locale& loc,
-           char format, char modifier = 0) -> OutputIt {
-  auto&& buf = basic_memory_buffer<Char>();
-  do_write<char>(buf, time, loc, format, modifier);
-  return write_encoded_tm_str(out, string_view(buf.data(), buf.size()), loc);
-}
-
-}  // namespace detail
-
-FMT_BEGIN_EXPORT
-
-/**
-  Converts given time since epoch as ``std::time_t`` value into calendar time,
-  expressed in local time. Unlike ``std::localtime``, this function is
-  thread-safe on most platforms.
- */
-inline std::tm localtime(std::time_t time) {
-  struct dispatcher {
-    std::time_t time_;
-    std::tm tm_;
-
-    dispatcher(std::time_t t) : time_(t) {}
-
-    bool run() {
-      using namespace fmt::detail;
-      return handle(localtime_r(&time_, &tm_));
-    }
-
-    bool handle(std::tm* tm) { return tm != nullptr; }
-
-    bool handle(detail::null<>) {
-      using namespace fmt::detail;
-      return fallback(localtime_s(&tm_, &time_));
-    }
-
-    bool fallback(int res) { return res == 0; }
-
-#if !FMT_MSC_VERSION
-    bool fallback(detail::null<>) {
-      using namespace fmt::detail;
-      std::tm* tm = std::localtime(&time_);
-      if (tm) tm_ = *tm;
-      return tm != nullptr;
-    }
-#endif
-  };
-  dispatcher lt(time);
-  // Too big time values may be unsupported.
-  if (!lt.run()) FMT_THROW(format_error("time_t value out of range"));
-  return lt.tm_;
-}
-
-#if FMT_USE_LOCAL_TIME
-template <typename Duration>
-inline auto localtime(std::chrono::local_time<Duration> time) -> std::tm {
-  return localtime(std::chrono::system_clock::to_time_t(
-      std::chrono::current_zone()->to_sys(time)));
-}
-#endif
-
-/**
-  Converts given time since epoch as ``std::time_t`` value into calendar time,
-  expressed in Coordinated Universal Time (UTC). Unlike ``std::gmtime``, this
-  function is thread-safe on most platforms.
- */
-inline std::tm gmtime(std::time_t time) {
-  struct dispatcher {
-    std::time_t time_;
-    std::tm tm_;
-
-    dispatcher(std::time_t t) : time_(t) {}
-
-    bool run() {
-      using namespace fmt::detail;
-      return handle(gmtime_r(&time_, &tm_));
-    }
-
-    bool handle(std::tm* tm) { return tm != nullptr; }
-
-    bool handle(detail::null<>) {
-      using namespace fmt::detail;
-      return fallback(gmtime_s(&tm_, &time_));
-    }
-
-    bool fallback(int res) { return res == 0; }
-
-#if !FMT_MSC_VERSION
-    bool fallback(detail::null<>) {
-      std::tm* tm = std::gmtime(&time_);
-      if (tm) tm_ = *tm;
-      return tm != nullptr;
-    }
-#endif
-  };
-  auto gt = dispatcher(time);
-  // Too big time values may be unsupported.
-  if (!gt.run()) FMT_THROW(format_error("time_t value out of range"));
-  return gt.tm_;
-}
-
-inline std::tm gmtime(
-    std::chrono::time_point<std::chrono::system_clock> time_point) {
-  return gmtime(std::chrono::system_clock::to_time_t(time_point));
-}
-
-namespace detail {
-
-// Writes two-digit numbers a, b and c separated by sep to buf.
-// The method by Pavel Novikov based on
-// https://johnnylee-sde.github.io/Fast-unsigned-integer-to-time-string/.
-inline void write_digit2_separated(char* buf, unsigned a, unsigned b,
-                                   unsigned c, char sep) {
-  unsigned long long digits =
-      a | (b << 24) | (static_cast<unsigned long long>(c) << 48);
-  // Convert each value to BCD.
-  // We have x = a * 10 + b and we want to convert it to BCD y = a * 16 + b.
-  // The difference is
-  //   y - x = a * 6
-  // a can be found from x:
-  //   a = floor(x / 10)
-  // then
-  //   y = x + a * 6 = x + floor(x / 10) * 6
-  // floor(x / 10) is (x * 205) >> 11 (needs 16 bits).
-  digits += (((digits * 205) >> 11) & 0x000f00000f00000f) * 6;
-  // Put low nibbles to high bytes and high nibbles to low bytes.
-  digits = ((digits & 0x00f00000f00000f0) >> 4) |
-           ((digits & 0x000f00000f00000f) << 8);
-  auto usep = static_cast<unsigned long long>(sep);
-  // Add ASCII '0' to each digit byte and insert separators.
-  digits |= 0x3030003030003030 | (usep << 16) | (usep << 40);
-
-  constexpr const size_t len = 8;
-  if (const_check(is_big_endian())) {
-    char tmp[len];
-    std::memcpy(tmp, &digits, len);
-    std::reverse_copy(tmp, tmp + len, buf);
-  } else {
-    std::memcpy(buf, &digits, len);
-  }
-}
-
-template <typename Period> FMT_CONSTEXPR inline const char* get_units() {
-  if (std::is_same<Period, std::atto>::value) return "as";
-  if (std::is_same<Period, std::femto>::value) return "fs";
-  if (std::is_same<Period, std::pico>::value) return "ps";
-  if (std::is_same<Period, std::nano>::value) return "ns";
-  if (std::is_same<Period, std::micro>::value) return "µs";
-  if (std::is_same<Period, std::milli>::value) return "ms";
-  if (std::is_same<Period, std::centi>::value) return "cs";
-  if (std::is_same<Period, std::deci>::value) return "ds";
-  if (std::is_same<Period, std::ratio<1>>::value) return "s";
-  if (std::is_same<Period, std::deca>::value) return "das";
-  if (std::is_same<Period, std::hecto>::value) return "hs";
-  if (std::is_same<Period, std::kilo>::value) return "ks";
-  if (std::is_same<Period, std::mega>::value) return "Ms";
-  if (std::is_same<Period, std::giga>::value) return "Gs";
-  if (std::is_same<Period, std::tera>::value) return "Ts";
-  if (std::is_same<Period, std::peta>::value) return "Ps";
-  if (std::is_same<Period, std::exa>::value) return "Es";
-  if (std::is_same<Period, std::ratio<60>>::value) return "min";
-  if (std::is_same<Period, std::ratio<3600>>::value) return "h";
-  if (std::is_same<Period, std::ratio<86400>>::value) return "d";
-  return nullptr;
-}
-
-enum class numeric_system {
-  standard,
-  // Alternative numeric system, e.g. 十二 instead of 12 in ja_JP locale.
-  alternative
-};
-
-// Glibc extensions for formatting numeric values.
-enum class pad_type {
-  unspecified,
-  // Do not pad a numeric result string.
-  none,
-  // Pad a numeric result string with zeros even if the conversion specifier
-  // character uses space-padding by default.
-  zero,
-  // Pad a numeric result string with spaces.
-  space,
-};
-
-template <typename OutputIt>
-auto write_padding(OutputIt out, pad_type pad, int width) -> OutputIt {
-  if (pad == pad_type::none) return out;
-  return std::fill_n(out, width, pad == pad_type::space ? ' ' : '0');
-}
-
-template <typename OutputIt>
-auto write_padding(OutputIt out, pad_type pad) -> OutputIt {
-  if (pad != pad_type::none) *out++ = pad == pad_type::space ? ' ' : '0';
-  return out;
-}
-
-// Parses a put_time-like format string and invokes handler actions.
-template <typename Char, typename Handler>
-FMT_CONSTEXPR const Char* parse_chrono_format(const Char* begin,
-                                              const Char* end,
-                                              Handler&& handler) {
-  if (begin == end || *begin == '}') return begin;
-  if (*begin != '%') FMT_THROW(format_error("invalid format"));
-  auto ptr = begin;
-  pad_type pad = pad_type::unspecified;
-  while (ptr != end) {
-    auto c = *ptr;
-    if (c == '}') break;
-    if (c != '%') {
-      ++ptr;
-      continue;
-    }
-    if (begin != ptr) handler.on_text(begin, ptr);
-    ++ptr;  // consume '%'
-    if (ptr == end) FMT_THROW(format_error("invalid format"));
-    c = *ptr;
-    switch (c) {
-    case '_':
-      pad = pad_type::space;
-      ++ptr;
-      break;
-    case '-':
-      pad = pad_type::none;
-      ++ptr;
-      break;
-    case '0':
-      pad = pad_type::zero;
-      ++ptr;
-      break;
-    }
-    if (ptr == end) FMT_THROW(format_error("invalid format"));
-    c = *ptr++;
-    switch (c) {
-    case '%':
-      handler.on_text(ptr - 1, ptr);
-      break;
-    case 'n': {
-      const Char newline[] = {'\n'};
-      handler.on_text(newline, newline + 1);
-      break;
-    }
-    case 't': {
-      const Char tab[] = {'\t'};
-      handler.on_text(tab, tab + 1);
-      break;
-    }
-    // Year:
-    case 'Y':
-      handler.on_year(numeric_system::standard);
-      break;
-    case 'y':
-      handler.on_short_year(numeric_system::standard);
-      break;
-    case 'C':
-      handler.on_century(numeric_system::standard);
-      break;
-    case 'G':
-      handler.on_iso_week_based_year();
-      break;
-    case 'g':
-      handler.on_iso_week_based_short_year();
-      break;
-    // Day of the week:
-    case 'a':
-      handler.on_abbr_weekday();
-      break;
-    case 'A':
-      handler.on_full_weekday();
-      break;
-    case 'w':
-      handler.on_dec0_weekday(numeric_system::standard);
-      break;
-    case 'u':
-      handler.on_dec1_weekday(numeric_system::standard);
-      break;
-    // Month:
-    case 'b':
-    case 'h':
-      handler.on_abbr_month();
-      break;
-    case 'B':
-      handler.on_full_month();
-      break;
-    case 'm':
-      handler.on_dec_month(numeric_system::standard);
-      break;
-    // Day of the year/month:
-    case 'U':
-      handler.on_dec0_week_of_year(numeric_system::standard);
-      break;
-    case 'W':
-      handler.on_dec1_week_of_year(numeric_system::standard);
-      break;
-    case 'V':
-      handler.on_iso_week_of_year(numeric_system::standard);
-      break;
-    case 'j':
-      handler.on_day_of_year();
-      break;
-    case 'd':
-      handler.on_day_of_month(numeric_system::standard);
-      break;
-    case 'e':
-      handler.on_day_of_month_space(numeric_system::standard);
-      break;
-    // Hour, minute, second:
-    case 'H':
-      handler.on_24_hour(numeric_system::standard, pad);
-      break;
-    case 'I':
-      handler.on_12_hour(numeric_system::standard, pad);
-      break;
-    case 'M':
-      handler.on_minute(numeric_system::standard, pad);
-      break;
-    case 'S':
-      handler.on_second(numeric_system::standard, pad);
-      break;
-    // Other:
-    case 'c':
-      handler.on_datetime(numeric_system::standard);
-      break;
-    case 'x':
-      handler.on_loc_date(numeric_system::standard);
-      break;
-    case 'X':
-      handler.on_loc_time(numeric_system::standard);
-      break;
-    case 'D':
-      handler.on_us_date();
-      break;
-    case 'F':
-      handler.on_iso_date();
-      break;
-    case 'r':
-      handler.on_12_hour_time();
-      break;
-    case 'R':
-      handler.on_24_hour_time();
-      break;
-    case 'T':
-      handler.on_iso_time();
-      break;
-    case 'p':
-      handler.on_am_pm();
-      break;
-    case 'Q':
-      handler.on_duration_value();
-      break;
-    case 'q':
-      handler.on_duration_unit();
-      break;
-    case 'z':
-      handler.on_utc_offset(numeric_system::standard);
-      break;
-    case 'Z':
-      handler.on_tz_name();
-      break;
-    // Alternative representation:
-    case 'E': {
-      if (ptr == end) FMT_THROW(format_error("invalid format"));
-      c = *ptr++;
-      switch (c) {
-      case 'Y':
-        handler.on_year(numeric_system::alternative);
-        break;
-      case 'y':
-        handler.on_offset_year();
-        break;
-      case 'C':
-        handler.on_century(numeric_system::alternative);
-        break;
-      case 'c':
-        handler.on_datetime(numeric_system::alternative);
-        break;
-      case 'x':
-        handler.on_loc_date(numeric_system::alternative);
-        break;
-      case 'X':
-        handler.on_loc_time(numeric_system::alternative);
-        break;
-      case 'z':
-        handler.on_utc_offset(numeric_system::alternative);
-        break;
-      default:
-        FMT_THROW(format_error("invalid format"));
-      }
-      break;
-    }
-    case 'O':
-      if (ptr == end) FMT_THROW(format_error("invalid format"));
-      c = *ptr++;
-      switch (c) {
-      case 'y':
-        handler.on_short_year(numeric_system::alternative);
-        break;
-      case 'm':
-        handler.on_dec_month(numeric_system::alternative);
-        break;
-      case 'U':
-        handler.on_dec0_week_of_year(numeric_system::alternative);
-        break;
-      case 'W':
-        handler.on_dec1_week_of_year(numeric_system::alternative);
-        break;
-      case 'V':
-        handler.on_iso_week_of_year(numeric_system::alternative);
-        break;
-      case 'd':
-        handler.on_day_of_month(numeric_system::alternative);
-        break;
-      case 'e':
-        handler.on_day_of_month_space(numeric_system::alternative);
-        break;
-      case 'w':
-        handler.on_dec0_weekday(numeric_system::alternative);
-        break;
-      case 'u':
-        handler.on_dec1_weekday(numeric_system::alternative);
-        break;
-      case 'H':
-        handler.on_24_hour(numeric_system::alternative, pad);
-        break;
-      case 'I':
-        handler.on_12_hour(numeric_system::alternative, pad);
-        break;
-      case 'M':
-        handler.on_minute(numeric_system::alternative, pad);
-        break;
-      case 'S':
-        handler.on_second(numeric_system::alternative, pad);
-        break;
-      case 'z':
-        handler.on_utc_offset(numeric_system::alternative);
-        break;
-      default:
-        FMT_THROW(format_error("invalid format"));
-      }
-      break;
-    default:
-      FMT_THROW(format_error("invalid format"));
-    }
-    begin = ptr;
-  }
-  if (begin != ptr) handler.on_text(begin, ptr);
-  return ptr;
-}
-
-template <typename Derived> struct null_chrono_spec_handler {
-  FMT_CONSTEXPR void unsupported() {
-    static_cast<Derived*>(this)->unsupported();
-  }
-  FMT_CONSTEXPR void on_year(numeric_system) { unsupported(); }
-  FMT_CONSTEXPR void on_short_year(numeric_system) { unsupported(); }
-  FMT_CONSTEXPR void on_offset_year() { unsupported(); }
-  FMT_CONSTEXPR void on_century(numeric_system) { unsupported(); }
-  FMT_CONSTEXPR void on_iso_week_based_year() { unsupported(); }
-  FMT_CONSTEXPR void on_iso_week_based_short_year() { unsupported(); }
-  FMT_CONSTEXPR void on_abbr_weekday() { unsupported(); }
-  FMT_CONSTEXPR void on_full_weekday() { unsupported(); }
-  FMT_CONSTEXPR void on_dec0_weekday(numeric_system) { unsupported(); }
-  FMT_CONSTEXPR void on_dec1_weekday(numeric_system) { unsupported(); }
-  FMT_CONSTEXPR void on_abbr_month() { unsupported(); }
-  FMT_CONSTEXPR void on_full_month() { unsupported(); }
-  FMT_CONSTEXPR void on_dec_month(numeric_system) { unsupported(); }
-  FMT_CONSTEXPR void on_dec0_week_of_year(numeric_system) { unsupported(); }
-  FMT_CONSTEXPR void on_dec1_week_of_year(numeric_system) { unsupported(); }
-  FMT_CONSTEXPR void on_iso_week_of_year(numeric_system) { unsupported(); }
-  FMT_CONSTEXPR void on_day_of_year() { unsupported(); }
-  FMT_CONSTEXPR void on_day_of_month(numeric_system) { unsupported(); }
-  FMT_CONSTEXPR void on_day_of_month_space(numeric_system) { unsupported(); }
-  FMT_CONSTEXPR void on_24_hour(numeric_system) { unsupported(); }
-  FMT_CONSTEXPR void on_12_hour(numeric_system) { unsupported(); }
-  FMT_CONSTEXPR void on_minute(numeric_system) { unsupported(); }
-  FMT_CONSTEXPR void on_second(numeric_system) { unsupported(); }
-  FMT_CONSTEXPR void on_datetime(numeric_system) { unsupported(); }
-  FMT_CONSTEXPR void on_loc_date(numeric_system) { unsupported(); }
-  FMT_CONSTEXPR void on_loc_time(numeric_system) { unsupported(); }
-  FMT_CONSTEXPR void on_us_date() { unsupported(); }
-  FMT_CONSTEXPR void on_iso_date() { unsupported(); }
-  FMT_CONSTEXPR void on_12_hour_time() { unsupported(); }
-  FMT_CONSTEXPR void on_24_hour_time() { unsupported(); }
-  FMT_CONSTEXPR void on_iso_time() { unsupported(); }
-  FMT_CONSTEXPR void on_am_pm() { unsupported(); }
-  FMT_CONSTEXPR void on_duration_value() { unsupported(); }
-  FMT_CONSTEXPR void on_duration_unit() { unsupported(); }
-  FMT_CONSTEXPR void on_utc_offset(numeric_system) { unsupported(); }
-  FMT_CONSTEXPR void on_tz_name() { unsupported(); }
-};
-
-struct tm_format_checker : null_chrono_spec_handler<tm_format_checker> {
-  FMT_NORETURN void unsupported() { FMT_THROW(format_error("no format")); }
-
-  template <typename Char>
-  FMT_CONSTEXPR void on_text(const Char*, const Char*) {}
-  FMT_CONSTEXPR void on_year(numeric_system) {}
-  FMT_CONSTEXPR void on_short_year(numeric_system) {}
-  FMT_CONSTEXPR void on_offset_year() {}
-  FMT_CONSTEXPR void on_century(numeric_system) {}
-  FMT_CONSTEXPR void on_iso_week_based_year() {}
-  FMT_CONSTEXPR void on_iso_week_based_short_year() {}
-  FMT_CONSTEXPR void on_abbr_weekday() {}
-  FMT_CONSTEXPR void on_full_weekday() {}
-  FMT_CONSTEXPR void on_dec0_weekday(numeric_system) {}
-  FMT_CONSTEXPR void on_dec1_weekday(numeric_system) {}
-  FMT_CONSTEXPR void on_abbr_month() {}
-  FMT_CONSTEXPR void on_full_month() {}
-  FMT_CONSTEXPR void on_dec_month(numeric_system) {}
-  FMT_CONSTEXPR void on_dec0_week_of_year(numeric_system) {}
-  FMT_CONSTEXPR void on_dec1_week_of_year(numeric_system) {}
-  FMT_CONSTEXPR void on_iso_week_of_year(numeric_system) {}
-  FMT_CONSTEXPR void on_day_of_year() {}
-  FMT_CONSTEXPR void on_day_of_month(numeric_system) {}
-  FMT_CONSTEXPR void on_day_of_month_space(numeric_system) {}
-  FMT_CONSTEXPR void on_24_hour(numeric_system, pad_type) {}
-  FMT_CONSTEXPR void on_12_hour(numeric_system, pad_type) {}
-  FMT_CONSTEXPR void on_minute(numeric_system, pad_type) {}
-  FMT_CONSTEXPR void on_second(numeric_system, pad_type) {}
-  FMT_CONSTEXPR void on_datetime(numeric_system) {}
-  FMT_CONSTEXPR void on_loc_date(numeric_system) {}
-  FMT_CONSTEXPR void on_loc_time(numeric_system) {}
-  FMT_CONSTEXPR void on_us_date() {}
-  FMT_CONSTEXPR void on_iso_date() {}
-  FMT_CONSTEXPR void on_12_hour_time() {}
-  FMT_CONSTEXPR void on_24_hour_time() {}
-  FMT_CONSTEXPR void on_iso_time() {}
-  FMT_CONSTEXPR void on_am_pm() {}
-  FMT_CONSTEXPR void on_utc_offset(numeric_system) {}
-  FMT_CONSTEXPR void on_tz_name() {}
-};
-
-inline const char* tm_wday_full_name(int wday) {
-  static constexpr const char* full_name_list[] = {
-      "Sunday",   "Monday", "Tuesday", "Wednesday",
-      "Thursday", "Friday", "Saturday"};
-  return wday >= 0 && wday <= 6 ? full_name_list[wday] : "?";
-}
-inline const char* tm_wday_short_name(int wday) {
-  static constexpr const char* short_name_list[] = {"Sun", "Mon", "Tue", "Wed",
-                                                    "Thu", "Fri", "Sat"};
-  return wday >= 0 && wday <= 6 ? short_name_list[wday] : "???";
-}
-
-inline const char* tm_mon_full_name(int mon) {
-  static constexpr const char* full_name_list[] = {
-      "January", "February", "March",     "April",   "May",      "June",
-      "July",    "August",   "September", "October", "November", "December"};
-  return mon >= 0 && mon <= 11 ? full_name_list[mon] : "?";
-}
-inline const char* tm_mon_short_name(int mon) {
-  static constexpr const char* short_name_list[] = {
-      "Jan", "Feb", "Mar", "Apr", "May", "Jun",
-      "Jul", "Aug", "Sep", "Oct", "Nov", "Dec",
-  };
-  return mon >= 0 && mon <= 11 ? short_name_list[mon] : "???";
-}
-
-template <typename T, typename = void>
-struct has_member_data_tm_gmtoff : std::false_type {};
-template <typename T>
-struct has_member_data_tm_gmtoff<T, void_t<decltype(T::tm_gmtoff)>>
-    : std::true_type {};
-
-template <typename T, typename = void>
-struct has_member_data_tm_zone : std::false_type {};
-template <typename T>
-struct has_member_data_tm_zone<T, void_t<decltype(T::tm_zone)>>
-    : std::true_type {};
-
-#if FMT_USE_TZSET
-inline void tzset_once() {
-  static bool init = []() -> bool {
-    _tzset();
-    return true;
-  }();
-  ignore_unused(init);
-}
-#endif
-
-// Converts value to Int and checks that it's in the range [0, upper).
-template <typename T, typename Int, FMT_ENABLE_IF(std::is_integral<T>::value)>
-inline Int to_nonnegative_int(T value, Int upper) {
-  FMT_ASSERT(std::is_unsigned<Int>::value ||
-                 (value >= 0 && to_unsigned(value) <= to_unsigned(upper)),
-             "invalid value");
-  (void)upper;
-  return static_cast<Int>(value);
-}
-template <typename T, typename Int, FMT_ENABLE_IF(!std::is_integral<T>::value)>
-inline Int to_nonnegative_int(T value, Int upper) {
-  if (value < 0 || value > static_cast<T>(upper))
-    FMT_THROW(format_error("invalid value"));
-  return static_cast<Int>(value);
-}
-
-constexpr long long pow10(std::uint32_t n) {
-  return n == 0 ? 1 : 10 * pow10(n - 1);
-}
-
-// Counts the number of fractional digits in the range [0, 18] according to the
-// C++20 spec. If more than 18 fractional digits are required then returns 6 for
-// microseconds precision.
-template <long long Num, long long Den, int N = 0,
-          bool Enabled = (N < 19) && (Num <= max_value<long long>() / 10)>
-struct count_fractional_digits {
-  static constexpr int value =
-      Num % Den == 0 ? N : count_fractional_digits<Num * 10, Den, N + 1>::value;
-};
-
-// Base case that doesn't instantiate any more templates
-// in order to avoid overflow.
-template <long long Num, long long Den, int N>
-struct count_fractional_digits<Num, Den, N, false> {
-  static constexpr int value = (Num % Den == 0) ? N : 6;
-};
-
-// Format subseconds which are given as an integer type with an appropriate
-// number of digits.
-template <typename Char, typename OutputIt, typename Duration>
-void write_fractional_seconds(OutputIt& out, Duration d, int precision = -1) {
-  constexpr auto num_fractional_digits =
-      count_fractional_digits<Duration::period::num,
-                              Duration::period::den>::value;
-
-  using subsecond_precision = std::chrono::duration<
-      typename std::common_type<typename Duration::rep,
-                                std::chrono::seconds::rep>::type,
-      std::ratio<1, detail::pow10(num_fractional_digits)>>;
-
-  const auto fractional =
-      d - std::chrono::duration_cast<std::chrono::seconds>(d);
-  const auto subseconds =
-      std::chrono::treat_as_floating_point<
-          typename subsecond_precision::rep>::value
-          ? fractional.count()
-          : std::chrono::duration_cast<subsecond_precision>(fractional).count();
-  auto n = static_cast<uint32_or_64_or_128_t<long long>>(subseconds);
-  const int num_digits = detail::count_digits(n);
-
-  int leading_zeroes = (std::max)(0, num_fractional_digits - num_digits);
-  if (precision < 0) {
-    FMT_ASSERT(!std::is_floating_point<typename Duration::rep>::value, "");
-    if (std::ratio_less<typename subsecond_precision::period,
-                        std::chrono::seconds::period>::value) {
-      *out++ = '.';
-      out = std::fill_n(out, leading_zeroes, '0');
-      out = format_decimal<Char>(out, n, num_digits).end;
-    }
-  } else {
-    *out++ = '.';
-    leading_zeroes = (std::min)(leading_zeroes, precision);
-    out = std::fill_n(out, leading_zeroes, '0');
-    int remaining = precision - leading_zeroes;
-    if (remaining != 0 && remaining < num_digits) {
-      n /= to_unsigned(detail::pow10(to_unsigned(num_digits - remaining)));
-      out = format_decimal<Char>(out, n, remaining).end;
-      return;
-    }
-    out = format_decimal<Char>(out, n, num_digits).end;
-    remaining -= num_digits;
-    out = std::fill_n(out, remaining, '0');
-  }
-}
-
-// Format subseconds which are given as a floating point type with an
-// appropriate number of digits. We cannot pass the Duration here, as we
-// explicitly need to pass the Rep value in the chrono_formatter.
-template <typename Duration>
-void write_floating_seconds(memory_buffer& buf, Duration duration,
-                            int num_fractional_digits = -1) {
-  using rep = typename Duration::rep;
-  FMT_ASSERT(std::is_floating_point<rep>::value, "");
-
-  auto val = duration.count();
-
-  if (num_fractional_digits < 0) {
-    // For `std::round` with fallback to `round`:
-    // On some toolchains `std::round` is not available (e.g. GCC 6).
-    using namespace std;
-    num_fractional_digits =
-        count_fractional_digits<Duration::period::num,
-                                Duration::period::den>::value;
-    if (num_fractional_digits < 6 && static_cast<rep>(round(val)) != val)
-      num_fractional_digits = 6;
-  }
-
-  format_to(std::back_inserter(buf), FMT_STRING("{:.{}f}"),
-            std::fmod(val * static_cast<rep>(Duration::period::num) /
-                          static_cast<rep>(Duration::period::den),
-                      static_cast<rep>(60)),
-            num_fractional_digits);
-}
-
-template <typename OutputIt, typename Char,
-          typename Duration = std::chrono::seconds>
-class tm_writer {
- private:
-  static constexpr int days_per_week = 7;
-
-  const std::locale& loc_;
-  const bool is_classic_;
-  OutputIt out_;
-  const Duration* subsecs_;
-  const std::tm& tm_;
-
-  auto tm_sec() const noexcept -> int {
-    FMT_ASSERT(tm_.tm_sec >= 0 && tm_.tm_sec <= 61, "");
-    return tm_.tm_sec;
-  }
-  auto tm_min() const noexcept -> int {
-    FMT_ASSERT(tm_.tm_min >= 0 && tm_.tm_min <= 59, "");
-    return tm_.tm_min;
-  }
-  auto tm_hour() const noexcept -> int {
-    FMT_ASSERT(tm_.tm_hour >= 0 && tm_.tm_hour <= 23, "");
-    return tm_.tm_hour;
-  }
-  auto tm_mday() const noexcept -> int {
-    FMT_ASSERT(tm_.tm_mday >= 1 && tm_.tm_mday <= 31, "");
-    return tm_.tm_mday;
-  }
-  auto tm_mon() const noexcept -> int {
-    FMT_ASSERT(tm_.tm_mon >= 0 && tm_.tm_mon <= 11, "");
-    return tm_.tm_mon;
-  }
-  auto tm_year() const noexcept -> long long { return 1900ll + tm_.tm_year; }
-  auto tm_wday() const noexcept -> int {
-    FMT_ASSERT(tm_.tm_wday >= 0 && tm_.tm_wday <= 6, "");
-    return tm_.tm_wday;
-  }
-  auto tm_yday() const noexcept -> int {
-    FMT_ASSERT(tm_.tm_yday >= 0 && tm_.tm_yday <= 365, "");
-    return tm_.tm_yday;
-  }
-
-  auto tm_hour12() const noexcept -> int {
-    const auto h = tm_hour();
-    const auto z = h < 12 ? h : h - 12;
-    return z == 0 ? 12 : z;
-  }
-
-  // POSIX and the C Standard are unclear or inconsistent about what %C and %y
-  // do if the year is negative or exceeds 9999. Use the convention that %C
-  // concatenated with %y yields the same output as %Y, and that %Y contains at
-  // least 4 characters, with more only if necessary.
-  auto split_year_lower(long long year) const noexcept -> int {
-    auto l = year % 100;
-    if (l < 0) l = -l;  // l in [0, 99]
-    return static_cast<int>(l);
-  }
-
-  // Algorithm:
-  // https://en.wikipedia.org/wiki/ISO_week_date#Calculating_the_week_number_from_a_month_and_day_of_the_month_or_ordinal_date
-  auto iso_year_weeks(long long curr_year) const noexcept -> int {
-    const auto prev_year = curr_year - 1;
-    const auto curr_p =
-        (curr_year + curr_year / 4 - curr_year / 100 + curr_year / 400) %
-        days_per_week;
-    const auto prev_p =
-        (prev_year + prev_year / 4 - prev_year / 100 + prev_year / 400) %
-        days_per_week;
-    return 52 + ((curr_p == 4 || prev_p == 3) ? 1 : 0);
-  }
-  auto iso_week_num(int tm_yday, int tm_wday) const noexcept -> int {
-    return (tm_yday + 11 - (tm_wday == 0 ? days_per_week : tm_wday)) /
-           days_per_week;
-  }
-  auto tm_iso_week_year() const noexcept -> long long {
-    const auto year = tm_year();
-    const auto w = iso_week_num(tm_yday(), tm_wday());
-    if (w < 1) return year - 1;
-    if (w > iso_year_weeks(year)) return year + 1;
-    return year;
-  }
-  auto tm_iso_week_of_year() const noexcept -> int {
-    const auto year = tm_year();
-    const auto w = iso_week_num(tm_yday(), tm_wday());
-    if (w < 1) return iso_year_weeks(year - 1);
-    if (w > iso_year_weeks(year)) return 1;
-    return w;
-  }
-
-  void write1(int value) {
-    *out_++ = static_cast<char>('0' + to_unsigned(value) % 10);
-  }
-  void write2(int value) {
-    const char* d = digits2(to_unsigned(value) % 100);
-    *out_++ = *d++;
-    *out_++ = *d;
-  }
-  void write2(int value, pad_type pad) {
-    unsigned int v = to_unsigned(value) % 100;
-    if (v >= 10) {
-      const char* d = digits2(v);
-      *out_++ = *d++;
-      *out_++ = *d;
-    } else {
-      out_ = detail::write_padding(out_, pad);
-      *out_++ = static_cast<char>('0' + v);
-    }
-  }
-
-  void write_year_extended(long long year) {
-    // At least 4 characters.
-    int width = 4;
-    if (year < 0) {
-      *out_++ = '-';
-      year = 0 - year;
-      --width;
-    }
-    uint32_or_64_or_128_t<long long> n = to_unsigned(year);
-    const int num_digits = count_digits(n);
-    if (width > num_digits) out_ = std::fill_n(out_, width - num_digits, '0');
-    out_ = format_decimal<Char>(out_, n, num_digits).end;
-  }
-  void write_year(long long year) {
-    if (year >= 0 && year < 10000) {
-      write2(static_cast<int>(year / 100));
-      write2(static_cast<int>(year % 100));
-    } else {
-      write_year_extended(year);
-    }
-  }
-
-  void write_utc_offset(long offset, numeric_system ns) {
-    if (offset < 0) {
-      *out_++ = '-';
-      offset = -offset;
-    } else {
-      *out_++ = '+';
-    }
-    offset /= 60;
-    write2(static_cast<int>(offset / 60));
-    if (ns != numeric_system::standard) *out_++ = ':';
-    write2(static_cast<int>(offset % 60));
-  }
-  template <typename T, FMT_ENABLE_IF(has_member_data_tm_gmtoff<T>::value)>
-  void format_utc_offset_impl(const T& tm, numeric_system ns) {
-    write_utc_offset(tm.tm_gmtoff, ns);
-  }
-  template <typename T, FMT_ENABLE_IF(!has_member_data_tm_gmtoff<T>::value)>
-  void format_utc_offset_impl(const T& tm, numeric_system ns) {
-#if defined(_WIN32) && defined(_UCRT)
-#  if FMT_USE_TZSET
-    tzset_once();
-#  endif
-    long offset = 0;
-    _get_timezone(&offset);
-    if (tm.tm_isdst) {
-      long dstbias = 0;
-      _get_dstbias(&dstbias);
-      offset += dstbias;
-    }
-    write_utc_offset(-offset, ns);
-#else
-    if (ns == numeric_system::standard) return format_localized('z');
-
-    // Extract timezone offset from timezone conversion functions.
-    std::tm gtm = tm;
-    std::time_t gt = std::mktime(&gtm);
-    std::tm ltm = gmtime(gt);
-    std::time_t lt = std::mktime(&ltm);
-    long offset = gt - lt;
-    write_utc_offset(offset, ns);
-#endif
-  }
-
-  template <typename T, FMT_ENABLE_IF(has_member_data_tm_zone<T>::value)>
-  void format_tz_name_impl(const T& tm) {
-    if (is_classic_)
-      out_ = write_tm_str<Char>(out_, tm.tm_zone, loc_);
-    else
-      format_localized('Z');
-  }
-  template <typename T, FMT_ENABLE_IF(!has_member_data_tm_zone<T>::value)>
-  void format_tz_name_impl(const T&) {
-    format_localized('Z');
-  }
-
-  void format_localized(char format, char modifier = 0) {
-    out_ = write<Char>(out_, tm_, loc_, format, modifier);
-  }
-
- public:
-  tm_writer(const std::locale& loc, OutputIt out, const std::tm& tm,
-            const Duration* subsecs = nullptr)
-      : loc_(loc),
-        is_classic_(loc_ == get_classic_locale()),
-        out_(out),
-        subsecs_(subsecs),
-        tm_(tm) {}
-
-  OutputIt out() const { return out_; }
-
-  FMT_CONSTEXPR void on_text(const Char* begin, const Char* end) {
-    out_ = copy_str<Char>(begin, end, out_);
-  }
-
-  void on_abbr_weekday() {
-    if (is_classic_)
-      out_ = write(out_, tm_wday_short_name(tm_wday()));
-    else
-      format_localized('a');
-  }
-  void on_full_weekday() {
-    if (is_classic_)
-      out_ = write(out_, tm_wday_full_name(tm_wday()));
-    else
-      format_localized('A');
-  }
-  void on_dec0_weekday(numeric_system ns) {
-    if (is_classic_ || ns == numeric_system::standard) return write1(tm_wday());
-    format_localized('w', 'O');
-  }
-  void on_dec1_weekday(numeric_system ns) {
-    if (is_classic_ || ns == numeric_system::standard) {
-      auto wday = tm_wday();
-      write1(wday == 0 ? days_per_week : wday);
-    } else {
-      format_localized('u', 'O');
-    }
-  }
-
-  void on_abbr_month() {
-    if (is_classic_)
-      out_ = write(out_, tm_mon_short_name(tm_mon()));
-    else
-      format_localized('b');
-  }
-  void on_full_month() {
-    if (is_classic_)
-      out_ = write(out_, tm_mon_full_name(tm_mon()));
-    else
-      format_localized('B');
-  }
-
-  void on_datetime(numeric_system ns) {
-    if (is_classic_) {
-      on_abbr_weekday();
-      *out_++ = ' ';
-      on_abbr_month();
-      *out_++ = ' ';
-      on_day_of_month_space(numeric_system::standard);
-      *out_++ = ' ';
-      on_iso_time();
-      *out_++ = ' ';
-      on_year(numeric_system::standard);
-    } else {
-      format_localized('c', ns == numeric_system::standard ? '\0' : 'E');
-    }
-  }
-  void on_loc_date(numeric_system ns) {
-    if (is_classic_)
-      on_us_date();
-    else
-      format_localized('x', ns == numeric_system::standard ? '\0' : 'E');
-  }
-  void on_loc_time(numeric_system ns) {
-    if (is_classic_)
-      on_iso_time();
-    else
-      format_localized('X', ns == numeric_system::standard ? '\0' : 'E');
-  }
-  void on_us_date() {
-    char buf[8];
-    write_digit2_separated(buf, to_unsigned(tm_mon() + 1),
-                           to_unsigned(tm_mday()),
-                           to_unsigned(split_year_lower(tm_year())), '/');
-    out_ = copy_str<Char>(std::begin(buf), std::end(buf), out_);
-  }
-  void on_iso_date() {
-    auto year = tm_year();
-    char buf[10];
-    size_t offset = 0;
-    if (year >= 0 && year < 10000) {
-      copy2(buf, digits2(static_cast<size_t>(year / 100)));
-    } else {
-      offset = 4;
-      write_year_extended(year);
-      year = 0;
-    }
-    write_digit2_separated(buf + 2, static_cast<unsigned>(year % 100),
-                           to_unsigned(tm_mon() + 1), to_unsigned(tm_mday()),
-                           '-');
-    out_ = copy_str<Char>(std::begin(buf) + offset, std::end(buf), out_);
-  }
-
-  void on_utc_offset(numeric_system ns) { format_utc_offset_impl(tm_, ns); }
-  void on_tz_name() { format_tz_name_impl(tm_); }
-
-  void on_year(numeric_system ns) {
-    if (is_classic_ || ns == numeric_system::standard)
-      return write_year(tm_year());
-    format_localized('Y', 'E');
-  }
-  void on_short_year(numeric_system ns) {
-    if (is_classic_ || ns == numeric_system::standard)
-      return write2(split_year_lower(tm_year()));
-    format_localized('y', 'O');
-  }
-  void on_offset_year() {
-    if (is_classic_) return write2(split_year_lower(tm_year()));
-    format_localized('y', 'E');
-  }
-
-  void on_century(numeric_system ns) {
-    if (is_classic_ || ns == numeric_system::standard) {
-      auto year = tm_year();
-      auto upper = year / 100;
-      if (year >= -99 && year < 0) {
-        // Zero upper on negative year.
-        *out_++ = '-';
-        *out_++ = '0';
-      } else if (upper >= 0 && upper < 100) {
-        write2(static_cast<int>(upper));
-      } else {
-        out_ = write<Char>(out_, upper);
-      }
-    } else {
-      format_localized('C', 'E');
-    }
-  }
-
-  void on_dec_month(numeric_system ns) {
-    if (is_classic_ || ns == numeric_system::standard)
-      return write2(tm_mon() + 1);
-    format_localized('m', 'O');
-  }
-
-  void on_dec0_week_of_year(numeric_system ns) {
-    if (is_classic_ || ns == numeric_system::standard)
-      return write2((tm_yday() + days_per_week - tm_wday()) / days_per_week);
-    format_localized('U', 'O');
-  }
-  void on_dec1_week_of_year(numeric_system ns) {
-    if (is_classic_ || ns == numeric_system::standard) {
-      auto wday = tm_wday();
-      write2((tm_yday() + days_per_week -
-              (wday == 0 ? (days_per_week - 1) : (wday - 1))) /
-             days_per_week);
-    } else {
-      format_localized('W', 'O');
-    }
-  }
-  void on_iso_week_of_year(numeric_system ns) {
-    if (is_classic_ || ns == numeric_system::standard)
-      return write2(tm_iso_week_of_year());
-    format_localized('V', 'O');
-  }
-
-  void on_iso_week_based_year() { write_year(tm_iso_week_year()); }
-  void on_iso_week_based_short_year() {
-    write2(split_year_lower(tm_iso_week_year()));
-  }
-
-  void on_day_of_year() {
-    auto yday = tm_yday() + 1;
-    write1(yday / 100);
-    write2(yday % 100);
-  }
-  void on_day_of_month(numeric_system ns) {
-    if (is_classic_ || ns == numeric_system::standard) return write2(tm_mday());
-    format_localized('d', 'O');
-  }
-  void on_day_of_month_space(numeric_system ns) {
-    if (is_classic_ || ns == numeric_system::standard) {
-      auto mday = to_unsigned(tm_mday()) % 100;
-      const char* d2 = digits2(mday);
-      *out_++ = mday < 10 ? ' ' : d2[0];
-      *out_++ = d2[1];
-    } else {
-      format_localized('e', 'O');
-    }
-  }
-
-  void on_24_hour(numeric_system ns, pad_type pad) {
-    if (is_classic_ || ns == numeric_system::standard)
-      return write2(tm_hour(), pad);
-    format_localized('H', 'O');
-  }
-  void on_12_hour(numeric_system ns, pad_type pad) {
-    if (is_classic_ || ns == numeric_system::standard)
-      return write2(tm_hour12(), pad);
-    format_localized('I', 'O');
-  }
-  void on_minute(numeric_system ns, pad_type pad) {
-    if (is_classic_ || ns == numeric_system::standard)
-      return write2(tm_min(), pad);
-    format_localized('M', 'O');
-  }
-
-  void on_second(numeric_system ns, pad_type pad) {
-    if (is_classic_ || ns == numeric_system::standard) {
-      write2(tm_sec(), pad);
-      if (subsecs_) {
-        if (std::is_floating_point<typename Duration::rep>::value) {
-          auto buf = memory_buffer();
-          write_floating_seconds(buf, *subsecs_);
-          if (buf.size() > 1) {
-            // Remove the leading "0", write something like ".123".
-            out_ = std::copy(buf.begin() + 1, buf.end(), out_);
-          }
-        } else {
-          write_fractional_seconds<Char>(out_, *subsecs_);
-        }
-      }
-    } else {
-      // Currently no formatting of subseconds when a locale is set.
-      format_localized('S', 'O');
-    }
-  }
-
-  void on_12_hour_time() {
-    if (is_classic_) {
-      char buf[8];
-      write_digit2_separated(buf, to_unsigned(tm_hour12()),
-                             to_unsigned(tm_min()), to_unsigned(tm_sec()), ':');
-      out_ = copy_str<Char>(std::begin(buf), std::end(buf), out_);
-      *out_++ = ' ';
-      on_am_pm();
-    } else {
-      format_localized('r');
-    }
-  }
-  void on_24_hour_time() {
-    write2(tm_hour());
-    *out_++ = ':';
-    write2(tm_min());
-  }
-  void on_iso_time() {
-    on_24_hour_time();
-    *out_++ = ':';
-    on_second(numeric_system::standard, pad_type::unspecified);
-  }
-
-  void on_am_pm() {
-    if (is_classic_) {
-      *out_++ = tm_hour() < 12 ? 'A' : 'P';
-      *out_++ = 'M';
-    } else {
-      format_localized('p');
-    }
-  }
-
-  // These apply to chrono durations but not tm.
-  void on_duration_value() {}
-  void on_duration_unit() {}
-};
-
-struct chrono_format_checker : null_chrono_spec_handler<chrono_format_checker> {
-  bool has_precision_integral = false;
-
-  FMT_NORETURN void unsupported() { FMT_THROW(format_error("no date")); }
-
-  template <typename Char>
-  FMT_CONSTEXPR void on_text(const Char*, const Char*) {}
-  FMT_CONSTEXPR void on_24_hour(numeric_system, pad_type) {}
-  FMT_CONSTEXPR void on_12_hour(numeric_system, pad_type) {}
-  FMT_CONSTEXPR void on_minute(numeric_system, pad_type) {}
-  FMT_CONSTEXPR void on_second(numeric_system, pad_type) {}
-  FMT_CONSTEXPR void on_12_hour_time() {}
-  FMT_CONSTEXPR void on_24_hour_time() {}
-  FMT_CONSTEXPR void on_iso_time() {}
-  FMT_CONSTEXPR void on_am_pm() {}
-  FMT_CONSTEXPR void on_duration_value() const {
-    if (has_precision_integral) {
-      FMT_THROW(format_error("precision not allowed for this argument type"));
-    }
-  }
-  FMT_CONSTEXPR void on_duration_unit() {}
-};
-
-template <typename T,
-          FMT_ENABLE_IF(std::is_integral<T>::value&& has_isfinite<T>::value)>
-inline bool isfinite(T) {
-  return true;
-}
-
-template <typename T, FMT_ENABLE_IF(std::is_integral<T>::value)>
-inline T mod(T x, int y) {
-  return x % static_cast<T>(y);
-}
-template <typename T, FMT_ENABLE_IF(std::is_floating_point<T>::value)>
-inline T mod(T x, int y) {
-  return std::fmod(x, static_cast<T>(y));
-}
-
-// If T is an integral type, maps T to its unsigned counterpart, otherwise
-// leaves it unchanged (unlike std::make_unsigned).
-template <typename T, bool INTEGRAL = std::is_integral<T>::value>
-struct make_unsigned_or_unchanged {
-  using type = T;
-};
-
-template <typename T> struct make_unsigned_or_unchanged<T, true> {
-  using type = typename std::make_unsigned<T>::type;
-};
-
-#if FMT_SAFE_DURATION_CAST
-// throwing version of safe_duration_cast
-template <typename To, typename FromRep, typename FromPeriod>
-To fmt_safe_duration_cast(std::chrono::duration<FromRep, FromPeriod> from) {
-  int ec;
-  To to = safe_duration_cast::safe_duration_cast<To>(from, ec);
-  if (ec) FMT_THROW(format_error("cannot format duration"));
-  return to;
-}
-#endif
-
-template <typename Rep, typename Period,
-          FMT_ENABLE_IF(std::is_integral<Rep>::value)>
-inline std::chrono::duration<Rep, std::milli> get_milliseconds(
-    std::chrono::duration<Rep, Period> d) {
-  // this may overflow and/or the result may not fit in the
-  // target type.
-#if FMT_SAFE_DURATION_CAST
-  using CommonSecondsType =
-      typename std::common_type<decltype(d), std::chrono::seconds>::type;
-  const auto d_as_common = fmt_safe_duration_cast<CommonSecondsType>(d);
-  const auto d_as_whole_seconds =
-      fmt_safe_duration_cast<std::chrono::seconds>(d_as_common);
-  // this conversion should be nonproblematic
-  const auto diff = d_as_common - d_as_whole_seconds;
-  const auto ms =
-      fmt_safe_duration_cast<std::chrono::duration<Rep, std::milli>>(diff);
-  return ms;
-#else
-  auto s = std::chrono::duration_cast<std::chrono::seconds>(d);
-  return std::chrono::duration_cast<std::chrono::milliseconds>(d - s);
-#endif
-}
-
-template <typename Char, typename Rep, typename OutputIt,
-          FMT_ENABLE_IF(std::is_integral<Rep>::value)>
-OutputIt format_duration_value(OutputIt out, Rep val, int) {
-  return write<Char>(out, val);
-}
-
-template <typename Char, typename Rep, typename OutputIt,
-          FMT_ENABLE_IF(std::is_floating_point<Rep>::value)>
-OutputIt format_duration_value(OutputIt out, Rep val, int precision) {
-  auto specs = format_specs<Char>();
-  specs.precision = precision;
-  specs.type = precision >= 0 ? presentation_type::fixed_lower
-                              : presentation_type::general_lower;
-  return write<Char>(out, val, specs);
-}
-
-template <typename Char, typename OutputIt>
-OutputIt copy_unit(string_view unit, OutputIt out, Char) {
-  return std::copy(unit.begin(), unit.end(), out);
-}
-
-template <typename OutputIt>
-OutputIt copy_unit(string_view unit, OutputIt out, wchar_t) {
-  // This works when wchar_t is UTF-32 because units only contain characters
-  // that have the same representation in UTF-16 and UTF-32.
-  utf8_to_utf16 u(unit);
-  return std::copy(u.c_str(), u.c_str() + u.size(), out);
-}
-
-template <typename Char, typename Period, typename OutputIt>
-OutputIt format_duration_unit(OutputIt out) {
-  if (const char* unit = get_units<Period>())
-    return copy_unit(string_view(unit), out, Char());
-  *out++ = '[';
-  out = write<Char>(out, Period::num);
-  if (const_check(Period::den != 1)) {
-    *out++ = '/';
-    out = write<Char>(out, Period::den);
-  }
-  *out++ = ']';
-  *out++ = 's';
-  return out;
-}
-
-class get_locale {
- private:
-  union {
-    std::locale locale_;
-  };
-  bool has_locale_ = false;
-
- public:
-  get_locale(bool localized, locale_ref loc) : has_locale_(localized) {
-    if (localized)
-      ::new (&locale_) std::locale(loc.template get<std::locale>());
-  }
-  ~get_locale() {
-    if (has_locale_) locale_.~locale();
-  }
-  operator const std::locale&() const {
-    return has_locale_ ? locale_ : get_classic_locale();
-  }
-};
-
-template <typename FormatContext, typename OutputIt, typename Rep,
-          typename Period>
-struct chrono_formatter {
-  FormatContext& context;
-  OutputIt out;
-  int precision;
-  bool localized = false;
-  // rep is unsigned to avoid overflow.
-  using rep =
-      conditional_t<std::is_integral<Rep>::value && sizeof(Rep) < sizeof(int),
-                    unsigned, typename make_unsigned_or_unchanged<Rep>::type>;
-  rep val;
-  using seconds = std::chrono::duration<rep>;
-  seconds s;
-  using milliseconds = std::chrono::duration<rep, std::milli>;
-  bool negative;
-
-  using char_type = typename FormatContext::char_type;
-  using tm_writer_type = tm_writer<OutputIt, char_type>;
-
-  chrono_formatter(FormatContext& ctx, OutputIt o,
-                   std::chrono::duration<Rep, Period> d)
-      : context(ctx),
-        out(o),
-        val(static_cast<rep>(d.count())),
-        negative(false) {
-    if (d.count() < 0) {
-      val = 0 - val;
-      negative = true;
-    }
-
-    // this may overflow and/or the result may not fit in the
-    // target type.
-#if FMT_SAFE_DURATION_CAST
-    // might need checked conversion (rep!=Rep)
-    auto tmpval = std::chrono::duration<rep, Period>(val);
-    s = fmt_safe_duration_cast<seconds>(tmpval);
-#else
-    s = std::chrono::duration_cast<seconds>(
-        std::chrono::duration<rep, Period>(val));
-#endif
-  }
-
-  // returns true if nan or inf, writes to out.
-  bool handle_nan_inf() {
-    if (isfinite(val)) {
-      return false;
-    }
-    if (isnan(val)) {
-      write_nan();
-      return true;
-    }
-    // must be +-inf
-    if (val > 0) {
-      write_pinf();
-    } else {
-      write_ninf();
-    }
-    return true;
-  }
-
-  Rep hour() const { return static_cast<Rep>(mod((s.count() / 3600), 24)); }
-
-  Rep hour12() const {
-    Rep hour = static_cast<Rep>(mod((s.count() / 3600), 12));
-    return hour <= 0 ? 12 : hour;
-  }
-
-  Rep minute() const { return static_cast<Rep>(mod((s.count() / 60), 60)); }
-  Rep second() const { return static_cast<Rep>(mod(s.count(), 60)); }
-
-  std::tm time() const {
-    auto time = std::tm();
-    time.tm_hour = to_nonnegative_int(hour(), 24);
-    time.tm_min = to_nonnegative_int(minute(), 60);
-    time.tm_sec = to_nonnegative_int(second(), 60);
-    return time;
-  }
-
-  void write_sign() {
-    if (negative) {
-      *out++ = '-';
-      negative = false;
-    }
-  }
-
-  void write(Rep value, int width, pad_type pad = pad_type::unspecified) {
-    write_sign();
-    if (isnan(value)) return write_nan();
-    uint32_or_64_or_128_t<int> n =
-        to_unsigned(to_nonnegative_int(value, max_value<int>()));
-    int num_digits = detail::count_digits(n);
-    if (width > num_digits) {
-      out = detail::write_padding(out, pad, width - num_digits);
-    }
-    out = format_decimal<char_type>(out, n, num_digits).end;
-  }
-
-  void write_nan() { std::copy_n("nan", 3, out); }
-  void write_pinf() { std::copy_n("inf", 3, out); }
-  void write_ninf() { std::copy_n("-inf", 4, out); }
-
-  template <typename Callback, typename... Args>
-  void format_tm(const tm& time, Callback cb, Args... args) {
-    if (isnan(val)) return write_nan();
-    get_locale loc(localized, context.locale());
-    auto w = tm_writer_type(loc, out, time);
-    (w.*cb)(args...);
-    out = w.out();
-  }
-
-  void on_text(const char_type* begin, const char_type* end) {
-    std::copy(begin, end, out);
-  }
-
-  // These are not implemented because durations don't have date information.
-  void on_abbr_weekday() {}
-  void on_full_weekday() {}
-  void on_dec0_weekday(numeric_system) {}
-  void on_dec1_weekday(numeric_system) {}
-  void on_abbr_month() {}
-  void on_full_month() {}
-  void on_datetime(numeric_system) {}
-  void on_loc_date(numeric_system) {}
-  void on_loc_time(numeric_system) {}
-  void on_us_date() {}
-  void on_iso_date() {}
-  void on_utc_offset(numeric_system) {}
-  void on_tz_name() {}
-  void on_year(numeric_system) {}
-  void on_short_year(numeric_system) {}
-  void on_offset_year() {}
-  void on_century(numeric_system) {}
-  void on_iso_week_based_year() {}
-  void on_iso_week_based_short_year() {}
-  void on_dec_month(numeric_system) {}
-  void on_dec0_week_of_year(numeric_system) {}
-  void on_dec1_week_of_year(numeric_system) {}
-  void on_iso_week_of_year(numeric_system) {}
-  void on_day_of_year() {}
-  void on_day_of_month(numeric_system) {}
-  void on_day_of_month_space(numeric_system) {}
-
-  void on_24_hour(numeric_system ns, pad_type pad) {
-    if (handle_nan_inf()) return;
-
-    if (ns == numeric_system::standard) return write(hour(), 2, pad);
-    auto time = tm();
-    time.tm_hour = to_nonnegative_int(hour(), 24);
-    format_tm(time, &tm_writer_type::on_24_hour, ns, pad);
-  }
-
-  void on_12_hour(numeric_system ns, pad_type pad) {
-    if (handle_nan_inf()) return;
-
-    if (ns == numeric_system::standard) return write(hour12(), 2, pad);
-    auto time = tm();
-    time.tm_hour = to_nonnegative_int(hour12(), 12);
-    format_tm(time, &tm_writer_type::on_12_hour, ns, pad);
-  }
-
-  void on_minute(numeric_system ns, pad_type pad) {
-    if (handle_nan_inf()) return;
-
-    if (ns == numeric_system::standard) return write(minute(), 2, pad);
-    auto time = tm();
-    time.tm_min = to_nonnegative_int(minute(), 60);
-    format_tm(time, &tm_writer_type::on_minute, ns, pad);
-  }
-
-  void on_second(numeric_system ns, pad_type pad) {
-    if (handle_nan_inf()) return;
-
-    if (ns == numeric_system::standard) {
-      if (std::is_floating_point<rep>::value) {
-        auto buf = memory_buffer();
-        write_floating_seconds(buf, std::chrono::duration<rep, Period>(val),
-                               precision);
-        if (negative) *out++ = '-';
-        if (buf.size() < 2 || buf[1] == '.') {
-          out = detail::write_padding(out, pad);
-        }
-        out = std::copy(buf.begin(), buf.end(), out);
-      } else {
-        write(second(), 2, pad);
-        write_fractional_seconds<char_type>(
-            out, std::chrono::duration<rep, Period>(val), precision);
-      }
-      return;
-    }
-    auto time = tm();
-    time.tm_sec = to_nonnegative_int(second(), 60);
-    format_tm(time, &tm_writer_type::on_second, ns, pad);
-  }
-
-  void on_12_hour_time() {
-    if (handle_nan_inf()) return;
-    format_tm(time(), &tm_writer_type::on_12_hour_time);
-  }
-
-  void on_24_hour_time() {
-    if (handle_nan_inf()) {
-      *out++ = ':';
-      handle_nan_inf();
-      return;
-    }
-
-    write(hour(), 2);
-    *out++ = ':';
-    write(minute(), 2);
-  }
-
-  void on_iso_time() {
-    on_24_hour_time();
-    *out++ = ':';
-    if (handle_nan_inf()) return;
-    on_second(numeric_system::standard, pad_type::unspecified);
-  }
-
-  void on_am_pm() {
-    if (handle_nan_inf()) return;
-    format_tm(time(), &tm_writer_type::on_am_pm);
-  }
-
-  void on_duration_value() {
-    if (handle_nan_inf()) return;
-    write_sign();
-    out = format_duration_value<char_type>(out, val, precision);
-  }
-
-  void on_duration_unit() {
-    out = format_duration_unit<char_type, Period>(out);
-  }
-};
-
-}  // namespace detail
-
-#if defined(__cpp_lib_chrono) && __cpp_lib_chrono >= 201907
-using weekday = std::chrono::weekday;
-#else
-// A fallback version of weekday.
-class weekday {
- private:
-  unsigned char value;
-
- public:
-  weekday() = default;
-  explicit constexpr weekday(unsigned wd) noexcept
-      : value(static_cast<unsigned char>(wd != 7 ? wd : 0)) {}
-  constexpr unsigned c_encoding() const noexcept { return value; }
-};
-
-class year_month_day {};
-#endif
-
-// A rudimentary weekday formatter.
-template <typename Char> struct formatter<weekday, Char> {
- private:
-  bool localized = false;
-
- public:
-  FMT_CONSTEXPR auto parse(basic_format_parse_context<Char>& ctx)
-      -> decltype(ctx.begin()) {
-    auto begin = ctx.begin(), end = ctx.end();
-    if (begin != end && *begin == 'L') {
-      ++begin;
-      localized = true;
-    }
-    return begin;
-  }
-
-  template <typename FormatContext>
-  auto format(weekday wd, FormatContext& ctx) const -> decltype(ctx.out()) {
-    auto time = std::tm();
-    time.tm_wday = static_cast<int>(wd.c_encoding());
-    detail::get_locale loc(localized, ctx.locale());
-    auto w = detail::tm_writer<decltype(ctx.out()), Char>(loc, ctx.out(), time);
-    w.on_abbr_weekday();
-    return w.out();
-  }
-};
-
-template <typename Rep, typename Period, typename Char>
-struct formatter<std::chrono::duration<Rep, Period>, Char> {
- private:
-  format_specs<Char> specs_;
-  detail::arg_ref<Char> width_ref_;
-  detail::arg_ref<Char> precision_ref_;
-  bool localized_ = false;
-  basic_string_view<Char> format_str_;
-
- public:
-  FMT_CONSTEXPR auto parse(basic_format_parse_context<Char>& ctx)
-      -> decltype(ctx.begin()) {
-    auto it = ctx.begin(), end = ctx.end();
-    if (it == end || *it == '}') return it;
-
-    it = detail::parse_align(it, end, specs_);
-    if (it == end) return it;
-
-    it = detail::parse_dynamic_spec(it, end, specs_.width, width_ref_, ctx);
-    if (it == end) return it;
-
-    auto checker = detail::chrono_format_checker();
-    if (*it == '.') {
-      checker.has_precision_integral = !std::is_floating_point<Rep>::value;
-      it = detail::parse_precision(it, end, specs_.precision, precision_ref_,
-                                   ctx);
-    }
-    if (it != end && *it == 'L') {
-      localized_ = true;
-      ++it;
-    }
-    end = detail::parse_chrono_format(it, end, checker);
-    format_str_ = {it, detail::to_unsigned(end - it)};
-    return end;
-  }
-
-  template <typename FormatContext>
-  auto format(std::chrono::duration<Rep, Period> d, FormatContext& ctx) const
-      -> decltype(ctx.out()) {
-    auto specs = specs_;
-    auto precision = specs.precision;
-    specs.precision = -1;
-    auto begin = format_str_.begin(), end = format_str_.end();
-    // As a possible future optimization, we could avoid extra copying if width
-    // is not specified.
-    auto buf = basic_memory_buffer<Char>();
-    auto out = std::back_inserter(buf);
-    detail::handle_dynamic_spec<detail::width_checker>(specs.width, width_ref_,
-                                                       ctx);
-    detail::handle_dynamic_spec<detail::precision_checker>(precision,
-                                                           precision_ref_, ctx);
-    if (begin == end || *begin == '}') {
-      out = detail::format_duration_value<Char>(out, d.count(), precision);
-      detail::format_duration_unit<Char, Period>(out);
-    } else {
-      using chrono_formatter =
-          detail::chrono_formatter<FormatContext, decltype(out), Rep, Period>;
-      auto f = chrono_formatter(ctx, out, d);
-      f.precision = precision;
-      f.localized = localized_;
-      detail::parse_chrono_format(begin, end, f);
-    }
-    return detail::write(
-        ctx.out(), basic_string_view<Char>(buf.data(), buf.size()), specs);
-  }
-};
-
-template <typename Char, typename Duration>
-struct formatter<std::chrono::time_point<std::chrono::system_clock, Duration>,
-                 Char> : formatter<std::tm, Char> {
-  FMT_CONSTEXPR formatter() {
-    this->format_str_ = detail::string_literal<Char, '%', 'F', ' ', '%', 'T'>{};
-  }
-
-  template <typename FormatContext>
-  auto format(std::chrono::time_point<std::chrono::system_clock, Duration> val,
-              FormatContext& ctx) const -> decltype(ctx.out()) {
-    using period = typename Duration::period;
-    if (detail::const_check(
-            period::num != 1 || period::den != 1 ||
-            std::is_floating_point<typename Duration::rep>::value)) {
-      const auto epoch = val.time_since_epoch();
-      auto subsecs = std::chrono::duration_cast<Duration>(
-          epoch - std::chrono::duration_cast<std::chrono::seconds>(epoch));
-
-      if (subsecs.count() < 0) {
-        auto second =
-            std::chrono::duration_cast<Duration>(std::chrono::seconds(1));
-        if (epoch.count() < ((Duration::min)() + second).count())
-          FMT_THROW(format_error("duration is too small"));
-        subsecs += second;
-        val -= second;
-      }
-
-      return formatter<std::tm, Char>::do_format(
-          gmtime(std::chrono::time_point_cast<std::chrono::seconds>(val)), ctx,
-          &subsecs);
-    }
-
-    return formatter<std::tm, Char>::format(
-        gmtime(std::chrono::time_point_cast<std::chrono::seconds>(val)), ctx);
-  }
-};
-
-#if FMT_USE_LOCAL_TIME
-template <typename Char, typename Duration>
-struct formatter<std::chrono::local_time<Duration>, Char>
-    : formatter<std::tm, Char> {
-  FMT_CONSTEXPR formatter() {
-    this->format_str_ = detail::string_literal<Char, '%', 'F', ' ', '%', 'T'>{};
-  }
-
-  template <typename FormatContext>
-  auto format(std::chrono::local_time<Duration> val, FormatContext& ctx) const
-      -> decltype(ctx.out()) {
-    using period = typename Duration::period;
-    if (period::num != 1 || period::den != 1 ||
-        std::is_floating_point<typename Duration::rep>::value) {
-      const auto epoch = val.time_since_epoch();
-      const auto subsecs = std::chrono::duration_cast<Duration>(
-          epoch - std::chrono::duration_cast<std::chrono::seconds>(epoch));
-
-      return formatter<std::tm, Char>::do_format(
-          localtime(std::chrono::time_point_cast<std::chrono::seconds>(val)),
-          ctx, &subsecs);
-    }
-
-    return formatter<std::tm, Char>::format(
-        localtime(std::chrono::time_point_cast<std::chrono::seconds>(val)),
-        ctx);
-  }
-};
-#endif
-
-#if FMT_USE_UTC_TIME
-template <typename Char, typename Duration>
-struct formatter<std::chrono::time_point<std::chrono::utc_clock, Duration>,
-                 Char>
-    : formatter<std::chrono::time_point<std::chrono::system_clock, Duration>,
-                Char> {
-  template <typename FormatContext>
-  auto format(std::chrono::time_point<std::chrono::utc_clock, Duration> val,
-              FormatContext& ctx) const -> decltype(ctx.out()) {
-    return formatter<
-        std::chrono::time_point<std::chrono::system_clock, Duration>,
-        Char>::format(std::chrono::utc_clock::to_sys(val), ctx);
-  }
-};
-#endif
-
-template <typename Char> struct formatter<std::tm, Char> {
- private:
-  format_specs<Char> specs_;
-  detail::arg_ref<Char> width_ref_;
-
- protected:
-  basic_string_view<Char> format_str_;
-
-  template <typename FormatContext, typename Duration>
-  auto do_format(const std::tm& tm, FormatContext& ctx,
-                 const Duration* subsecs) const -> decltype(ctx.out()) {
-    auto specs = specs_;
-    auto buf = basic_memory_buffer<Char>();
-    auto out = std::back_inserter(buf);
-    detail::handle_dynamic_spec<detail::width_checker>(specs.width, width_ref_,
-                                                       ctx);
-
-    auto loc_ref = ctx.locale();
-    detail::get_locale loc(static_cast<bool>(loc_ref), loc_ref);
-    auto w =
-        detail::tm_writer<decltype(out), Char, Duration>(loc, out, tm, subsecs);
-    detail::parse_chrono_format(format_str_.begin(), format_str_.end(), w);
-    return detail::write(
-        ctx.out(), basic_string_view<Char>(buf.data(), buf.size()), specs);
-  }
-
- public:
-  FMT_CONSTEXPR auto parse(basic_format_parse_context<Char>& ctx)
-      -> decltype(ctx.begin()) {
-    auto it = ctx.begin(), end = ctx.end();
-    if (it == end || *it == '}') return it;
-
-    it = detail::parse_align(it, end, specs_);
-    if (it == end) return it;
-
-    it = detail::parse_dynamic_spec(it, end, specs_.width, width_ref_, ctx);
-    if (it == end) return it;
-
-    end = detail::parse_chrono_format(it, end, detail::tm_format_checker());
-    // Replace the default format_str only if the new spec is not empty.
-    if (end != it) format_str_ = {it, detail::to_unsigned(end - it)};
-    return end;
-  }
-
-  template <typename FormatContext>
-  auto format(const std::tm& tm, FormatContext& ctx) const
-      -> decltype(ctx.out()) {
-    return do_format<FormatContext, std::chrono::seconds>(tm, ctx, nullptr);
-  }
-};
-
-FMT_END_EXPORT
-FMT_END_NAMESPACE
-
-#endif  // FMT_CHRONO_H_
diff --git a/lib/fmt/include/fmt-vt/color.h b/lib/fmt/include/fmt-vt/color.h
deleted file mode 100644
index 57b7f5789a..0000000000
--- a/lib/fmt/include/fmt-vt/color.h
+++ /dev/null
@@ -1,633 +0,0 @@
-// Formatting library for C++ - color support
-//
-// Copyright (c) 2018 - present, Victor Zverovich and fmt contributors
-// All rights reserved.
-//
-// For the license information refer to format.h.
-
-#ifndef FMT_COLOR_H_
-#define FMT_COLOR_H_
-
-#include "format.h"
-
-FMT_BEGIN_NAMESPACE
-FMT_BEGIN_EXPORT
-
-enum class color : uint32_t {
-  alice_blue = 0xF0F8FF,               // rgb(240,248,255)
-  antique_white = 0xFAEBD7,            // rgb(250,235,215)
-  aqua = 0x00FFFF,                     // rgb(0,255,255)
-  aquamarine = 0x7FFFD4,               // rgb(127,255,212)
-  azure = 0xF0FFFF,                    // rgb(240,255,255)
-  beige = 0xF5F5DC,                    // rgb(245,245,220)
-  bisque = 0xFFE4C4,                   // rgb(255,228,196)
-  black = 0x000000,                    // rgb(0,0,0)
-  blanched_almond = 0xFFEBCD,          // rgb(255,235,205)
-  blue = 0x0000FF,                     // rgb(0,0,255)
-  blue_violet = 0x8A2BE2,              // rgb(138,43,226)
-  brown = 0xA52A2A,                    // rgb(165,42,42)
-  burly_wood = 0xDEB887,               // rgb(222,184,135)
-  cadet_blue = 0x5F9EA0,               // rgb(95,158,160)
-  chartreuse = 0x7FFF00,               // rgb(127,255,0)
-  chocolate = 0xD2691E,                // rgb(210,105,30)
-  coral = 0xFF7F50,                    // rgb(255,127,80)
-  cornflower_blue = 0x6495ED,          // rgb(100,149,237)
-  cornsilk = 0xFFF8DC,                 // rgb(255,248,220)
-  crimson = 0xDC143C,                  // rgb(220,20,60)
-  cyan = 0x00FFFF,                     // rgb(0,255,255)
-  dark_blue = 0x00008B,                // rgb(0,0,139)
-  dark_cyan = 0x008B8B,                // rgb(0,139,139)
-  dark_golden_rod = 0xB8860B,          // rgb(184,134,11)
-  dark_gray = 0xA9A9A9,                // rgb(169,169,169)
-  dark_green = 0x006400,               // rgb(0,100,0)
-  dark_khaki = 0xBDB76B,               // rgb(189,183,107)
-  dark_magenta = 0x8B008B,             // rgb(139,0,139)
-  dark_olive_green = 0x556B2F,         // rgb(85,107,47)
-  dark_orange = 0xFF8C00,              // rgb(255,140,0)
-  dark_orchid = 0x9932CC,              // rgb(153,50,204)
-  dark_red = 0x8B0000,                 // rgb(139,0,0)
-  dark_salmon = 0xE9967A,              // rgb(233,150,122)
-  dark_sea_green = 0x8FBC8F,           // rgb(143,188,143)
-  dark_slate_blue = 0x483D8B,          // rgb(72,61,139)
-  dark_slate_gray = 0x2F4F4F,          // rgb(47,79,79)
-  dark_turquoise = 0x00CED1,           // rgb(0,206,209)
-  dark_violet = 0x9400D3,              // rgb(148,0,211)
-  deep_pink = 0xFF1493,                // rgb(255,20,147)
-  deep_sky_blue = 0x00BFFF,            // rgb(0,191,255)
-  dim_gray = 0x696969,                 // rgb(105,105,105)
-  dodger_blue = 0x1E90FF,              // rgb(30,144,255)
-  fire_brick = 0xB22222,               // rgb(178,34,34)
-  floral_white = 0xFFFAF0,             // rgb(255,250,240)
-  forest_green = 0x228B22,             // rgb(34,139,34)
-  fuchsia = 0xFF00FF,                  // rgb(255,0,255)
-  gainsboro = 0xDCDCDC,                // rgb(220,220,220)
-  ghost_white = 0xF8F8FF,              // rgb(248,248,255)
-  gold = 0xFFD700,                     // rgb(255,215,0)
-  golden_rod = 0xDAA520,               // rgb(218,165,32)
-  gray = 0x808080,                     // rgb(128,128,128)
-  green = 0x008000,                    // rgb(0,128,0)
-  green_yellow = 0xADFF2F,             // rgb(173,255,47)
-  honey_dew = 0xF0FFF0,                // rgb(240,255,240)
-  hot_pink = 0xFF69B4,                 // rgb(255,105,180)
-  indian_red = 0xCD5C5C,               // rgb(205,92,92)
-  indigo = 0x4B0082,                   // rgb(75,0,130)
-  ivory = 0xFFFFF0,                    // rgb(255,255,240)
-  khaki = 0xF0E68C,                    // rgb(240,230,140)
-  lavender = 0xE6E6FA,                 // rgb(230,230,250)
-  lavender_blush = 0xFFF0F5,           // rgb(255,240,245)
-  lawn_green = 0x7CFC00,               // rgb(124,252,0)
-  lemon_chiffon = 0xFFFACD,            // rgb(255,250,205)
-  light_blue = 0xADD8E6,               // rgb(173,216,230)
-  light_coral = 0xF08080,              // rgb(240,128,128)
-  light_cyan = 0xE0FFFF,               // rgb(224,255,255)
-  light_golden_rod_yellow = 0xFAFAD2,  // rgb(250,250,210)
-  light_gray = 0xD3D3D3,               // rgb(211,211,211)
-  light_green = 0x90EE90,              // rgb(144,238,144)
-  light_pink = 0xFFB6C1,               // rgb(255,182,193)
-  light_salmon = 0xFFA07A,             // rgb(255,160,122)
-  light_sea_green = 0x20B2AA,          // rgb(32,178,170)
-  light_sky_blue = 0x87CEFA,           // rgb(135,206,250)
-  light_slate_gray = 0x778899,         // rgb(119,136,153)
-  light_steel_blue = 0xB0C4DE,         // rgb(176,196,222)
-  light_yellow = 0xFFFFE0,             // rgb(255,255,224)
-  lime = 0x00FF00,                     // rgb(0,255,0)
-  lime_green = 0x32CD32,               // rgb(50,205,50)
-  linen = 0xFAF0E6,                    // rgb(250,240,230)
-  magenta = 0xFF00FF,                  // rgb(255,0,255)
-  maroon = 0x800000,                   // rgb(128,0,0)
-  medium_aquamarine = 0x66CDAA,        // rgb(102,205,170)
-  medium_blue = 0x0000CD,              // rgb(0,0,205)
-  medium_orchid = 0xBA55D3,            // rgb(186,85,211)
-  medium_purple = 0x9370DB,            // rgb(147,112,219)
-  medium_sea_green = 0x3CB371,         // rgb(60,179,113)
-  medium_slate_blue = 0x7B68EE,        // rgb(123,104,238)
-  medium_spring_green = 0x00FA9A,      // rgb(0,250,154)
-  medium_turquoise = 0x48D1CC,         // rgb(72,209,204)
-  medium_violet_red = 0xC71585,        // rgb(199,21,133)
-  midnight_blue = 0x191970,            // rgb(25,25,112)
-  mint_cream = 0xF5FFFA,               // rgb(245,255,250)
-  misty_rose = 0xFFE4E1,               // rgb(255,228,225)
-  moccasin = 0xFFE4B5,                 // rgb(255,228,181)
-  navajo_white = 0xFFDEAD,             // rgb(255,222,173)
-  navy = 0x000080,                     // rgb(0,0,128)
-  old_lace = 0xFDF5E6,                 // rgb(253,245,230)
-  olive = 0x808000,                    // rgb(128,128,0)
-  olive_drab = 0x6B8E23,               // rgb(107,142,35)
-  orange = 0xFFA500,                   // rgb(255,165,0)
-  orange_red = 0xFF4500,               // rgb(255,69,0)
-  orchid = 0xDA70D6,                   // rgb(218,112,214)
-  pale_golden_rod = 0xEEE8AA,          // rgb(238,232,170)
-  pale_green = 0x98FB98,               // rgb(152,251,152)
-  pale_turquoise = 0xAFEEEE,           // rgb(175,238,238)
-  pale_violet_red = 0xDB7093,          // rgb(219,112,147)
-  papaya_whip = 0xFFEFD5,              // rgb(255,239,213)
-  peach_puff = 0xFFDAB9,               // rgb(255,218,185)
-  peru = 0xCD853F,                     // rgb(205,133,63)
-  pink = 0xFFC0CB,                     // rgb(255,192,203)
-  plum = 0xDDA0DD,                     // rgb(221,160,221)
-  powder_blue = 0xB0E0E6,              // rgb(176,224,230)
-  purple = 0x800080,                   // rgb(128,0,128)
-  rebecca_purple = 0x663399,           // rgb(102,51,153)
-  red = 0xFF0000,                      // rgb(255,0,0)
-  rosy_brown = 0xBC8F8F,               // rgb(188,143,143)
-  royal_blue = 0x4169E1,               // rgb(65,105,225)
-  saddle_brown = 0x8B4513,             // rgb(139,69,19)
-  salmon = 0xFA8072,                   // rgb(250,128,114)
-  sandy_brown = 0xF4A460,              // rgb(244,164,96)
-  sea_green = 0x2E8B57,                // rgb(46,139,87)
-  sea_shell = 0xFFF5EE,                // rgb(255,245,238)
-  sienna = 0xA0522D,                   // rgb(160,82,45)
-  silver = 0xC0C0C0,                   // rgb(192,192,192)
-  sky_blue = 0x87CEEB,                 // rgb(135,206,235)
-  slate_blue = 0x6A5ACD,               // rgb(106,90,205)
-  slate_gray = 0x708090,               // rgb(112,128,144)
-  snow = 0xFFFAFA,                     // rgb(255,250,250)
-  spring_green = 0x00FF7F,             // rgb(0,255,127)
-  steel_blue = 0x4682B4,               // rgb(70,130,180)
-  tan = 0xD2B48C,                      // rgb(210,180,140)
-  teal = 0x008080,                     // rgb(0,128,128)
-  thistle = 0xD8BFD8,                  // rgb(216,191,216)
-  tomato = 0xFF6347,                   // rgb(255,99,71)
-  turquoise = 0x40E0D0,                // rgb(64,224,208)
-  violet = 0xEE82EE,                   // rgb(238,130,238)
-  wheat = 0xF5DEB3,                    // rgb(245,222,179)
-  white = 0xFFFFFF,                    // rgb(255,255,255)
-  white_smoke = 0xF5F5F5,              // rgb(245,245,245)
-  yellow = 0xFFFF00,                   // rgb(255,255,0)
-  yellow_green = 0x9ACD32              // rgb(154,205,50)
-};                                     // enum class color
-
-enum class terminal_color : uint8_t {
-  black = 30,
-  red,
-  green,
-  yellow,
-  blue,
-  magenta,
-  cyan,
-  white,
-  bright_black = 90,
-  bright_red,
-  bright_green,
-  bright_yellow,
-  bright_blue,
-  bright_magenta,
-  bright_cyan,
-  bright_white
-};
-
-enum class emphasis : uint8_t {
-  bold = 1,
-  faint = 1 << 1,
-  italic = 1 << 2,
-  underline = 1 << 3,
-  blink = 1 << 4,
-  reverse = 1 << 5,
-  conceal = 1 << 6,
-  strikethrough = 1 << 7,
-};
-
-// rgb is a struct for red, green and blue colors.
-// Using the name "rgb" makes some editors show the color in a tooltip.
-struct rgb {
-  FMT_CONSTEXPR rgb() : r(0), g(0), b(0) {}
-  FMT_CONSTEXPR rgb(uint8_t r_, uint8_t g_, uint8_t b_) : r(r_), g(g_), b(b_) {}
-  FMT_CONSTEXPR rgb(uint32_t hex)
-      : r((hex >> 16) & 0xFF), g((hex >> 8) & 0xFF), b(hex & 0xFF) {}
-  FMT_CONSTEXPR rgb(color hex)
-      : r((uint32_t(hex) >> 16) & 0xFF),
-        g((uint32_t(hex) >> 8) & 0xFF),
-        b(uint32_t(hex) & 0xFF) {}
-  uint8_t r;
-  uint8_t g;
-  uint8_t b;
-};
-
-namespace detail {
-
-// color is a struct of either a rgb color or a terminal color.
-struct color_type {
-  FMT_CONSTEXPR color_type() noexcept : is_rgb(), value{} {}
-  FMT_CONSTEXPR color_type(color rgb_color) noexcept : is_rgb(true), value{} {
-    value.rgb_color = static_cast<uint32_t>(rgb_color);
-  }
-  FMT_CONSTEXPR color_type(rgb rgb_color) noexcept : is_rgb(true), value{} {
-    value.rgb_color = (static_cast<uint32_t>(rgb_color.r) << 16) |
-                      (static_cast<uint32_t>(rgb_color.g) << 8) | rgb_color.b;
-  }
-  FMT_CONSTEXPR color_type(terminal_color term_color) noexcept
-      : is_rgb(), value{} {
-    value.term_color = static_cast<uint8_t>(term_color);
-  }
-  bool is_rgb;
-  union color_union {
-    uint8_t term_color;
-    uint32_t rgb_color;
-  } value;
-};
-}  // namespace detail
-
-/** A text style consisting of foreground and background colors and emphasis. */
-class text_style {
- public:
-  FMT_CONSTEXPR text_style(emphasis em = emphasis()) noexcept
-      : set_foreground_color(), set_background_color(), ems(em) {}
-
-  FMT_CONSTEXPR text_style& operator|=(const text_style& rhs) {
-    if (!set_foreground_color) {
-      set_foreground_color = rhs.set_foreground_color;
-      foreground_color = rhs.foreground_color;
-    } else if (rhs.set_foreground_color) {
-      if (!foreground_color.is_rgb || !rhs.foreground_color.is_rgb)
-        FMT_THROW(format_error("can't OR a terminal color"));
-      foreground_color.value.rgb_color |= rhs.foreground_color.value.rgb_color;
-    }
-
-    if (!set_background_color) {
-      set_background_color = rhs.set_background_color;
-      background_color = rhs.background_color;
-    } else if (rhs.set_background_color) {
-      if (!background_color.is_rgb || !rhs.background_color.is_rgb)
-        FMT_THROW(format_error("can't OR a terminal color"));
-      background_color.value.rgb_color |= rhs.background_color.value.rgb_color;
-    }
-
-    ems = static_cast<emphasis>(static_cast<uint8_t>(ems) |
-                                static_cast<uint8_t>(rhs.ems));
-    return *this;
-  }
-
-  friend FMT_CONSTEXPR text_style operator|(text_style lhs,
-                                            const text_style& rhs) {
-    return lhs |= rhs;
-  }
-
-  FMT_CONSTEXPR bool has_foreground() const noexcept {
-    return set_foreground_color;
-  }
-  FMT_CONSTEXPR bool has_background() const noexcept {
-    return set_background_color;
-  }
-  FMT_CONSTEXPR bool has_emphasis() const noexcept {
-    return static_cast<uint8_t>(ems) != 0;
-  }
-  FMT_CONSTEXPR detail::color_type get_foreground() const noexcept {
-    FMT_ASSERT(has_foreground(), "no foreground specified for this style");
-    return foreground_color;
-  }
-  FMT_CONSTEXPR detail::color_type get_background() const noexcept {
-    FMT_ASSERT(has_background(), "no background specified for this style");
-    return background_color;
-  }
-  FMT_CONSTEXPR emphasis get_emphasis() const noexcept {
-    FMT_ASSERT(has_emphasis(), "no emphasis specified for this style");
-    return ems;
-  }
-
- private:
-  FMT_CONSTEXPR text_style(bool is_foreground,
-                           detail::color_type text_color) noexcept
-      : set_foreground_color(), set_background_color(), ems() {
-    if (is_foreground) {
-      foreground_color = text_color;
-      set_foreground_color = true;
-    } else {
-      background_color = text_color;
-      set_background_color = true;
-    }
-  }
-
-  friend FMT_CONSTEXPR text_style fg(detail::color_type foreground) noexcept;
-
-  friend FMT_CONSTEXPR text_style bg(detail::color_type background) noexcept;
-
-  detail::color_type foreground_color;
-  detail::color_type background_color;
-  bool set_foreground_color;
-  bool set_background_color;
-  emphasis ems;
-};
-
-/** Creates a text style from the foreground (text) color. */
-FMT_CONSTEXPR inline text_style fg(detail::color_type foreground) noexcept {
-  return text_style(true, foreground);
-}
-
-/** Creates a text style from the background color. */
-FMT_CONSTEXPR inline text_style bg(detail::color_type background) noexcept {
-  return text_style(false, background);
-}
-
-FMT_CONSTEXPR inline text_style operator|(emphasis lhs, emphasis rhs) noexcept {
-  return text_style(lhs) | rhs;
-}
-
-namespace detail {
-
-template <typename Char> struct ansi_color_escape {
-  FMT_CONSTEXPR ansi_color_escape(detail::color_type text_color,
-                                  const char* esc) noexcept {
-    // If we have a terminal color, we need to output another escape code
-    // sequence.
-    if (!text_color.is_rgb) {
-      bool is_background = esc == string_view("\x1b[48;2;");
-      uint32_t value = text_color.value.term_color;
-      // Background ASCII codes are the same as the foreground ones but with
-      // 10 more.
-      if (is_background) value += 10u;
-
-      size_t index = 0;
-      buffer[index++] = static_cast<Char>('\x1b');
-      buffer[index++] = static_cast<Char>('[');
-
-      if (value >= 100u) {
-        buffer[index++] = static_cast<Char>('1');
-        value %= 100u;
-      }
-      buffer[index++] = static_cast<Char>('0' + value / 10u);
-      buffer[index++] = static_cast<Char>('0' + value % 10u);
-
-      buffer[index++] = static_cast<Char>('m');
-      buffer[index++] = static_cast<Char>('\0');
-      return;
-    }
-
-    for (int i = 0; i < 7; i++) {
-      buffer[i] = static_cast<Char>(esc[i]);
-    }
-    rgb color(text_color.value.rgb_color);
-    to_esc(color.r, buffer + 7, ';');
-    to_esc(color.g, buffer + 11, ';');
-    to_esc(color.b, buffer + 15, 'm');
-    buffer[19] = static_cast<Char>(0);
-  }
-  FMT_CONSTEXPR ansi_color_escape(emphasis em) noexcept {
-    uint8_t em_codes[num_emphases] = {};
-    if (has_emphasis(em, emphasis::bold)) em_codes[0] = 1;
-    if (has_emphasis(em, emphasis::faint)) em_codes[1] = 2;
-    if (has_emphasis(em, emphasis::italic)) em_codes[2] = 3;
-    if (has_emphasis(em, emphasis::underline)) em_codes[3] = 4;
-    if (has_emphasis(em, emphasis::blink)) em_codes[4] = 5;
-    if (has_emphasis(em, emphasis::reverse)) em_codes[5] = 7;
-    if (has_emphasis(em, emphasis::conceal)) em_codes[6] = 8;
-    if (has_emphasis(em, emphasis::strikethrough)) em_codes[7] = 9;
-
-    size_t index = 0;
-    for (size_t i = 0; i < num_emphases; ++i) {
-      if (!em_codes[i]) continue;
-      buffer[index++] = static_cast<Char>('\x1b');
-      buffer[index++] = static_cast<Char>('[');
-      buffer[index++] = static_cast<Char>('0' + em_codes[i]);
-      buffer[index++] = static_cast<Char>('m');
-    }
-    buffer[index++] = static_cast<Char>(0);
-  }
-  FMT_CONSTEXPR operator const Char*() const noexcept { return buffer; }
-
-  FMT_CONSTEXPR const Char* begin() const noexcept { return buffer; }
-  FMT_CONSTEXPR_CHAR_TRAITS const Char* end() const noexcept {
-    return buffer + std::char_traits<Char>::length(buffer);
-  }
-
- private:
-  static constexpr size_t num_emphases = 8;
-  Char buffer[7u + 3u * num_emphases + 1u];
-
-  static FMT_CONSTEXPR void to_esc(uint8_t c, Char* out,
-                                   char delimiter) noexcept {
-    out[0] = static_cast<Char>('0' + c / 100);
-    out[1] = static_cast<Char>('0' + c / 10 % 10);
-    out[2] = static_cast<Char>('0' + c % 10);
-    out[3] = static_cast<Char>(delimiter);
-  }
-  static FMT_CONSTEXPR bool has_emphasis(emphasis em, emphasis mask) noexcept {
-    return static_cast<uint8_t>(em) & static_cast<uint8_t>(mask);
-  }
-};
-
-template <typename Char>
-FMT_CONSTEXPR ansi_color_escape<Char> make_foreground_color(
-    detail::color_type foreground) noexcept {
-  return ansi_color_escape<Char>(foreground, "\x1b[38;2;");
-}
-
-template <typename Char>
-FMT_CONSTEXPR ansi_color_escape<Char> make_background_color(
-    detail::color_type background) noexcept {
-  return ansi_color_escape<Char>(background, "\x1b[48;2;");
-}
-
-template <typename Char>
-FMT_CONSTEXPR ansi_color_escape<Char> make_emphasis(emphasis em) noexcept {
-  return ansi_color_escape<Char>(em);
-}
-
-template <typename Char> inline void reset_color(buffer<Char>& buffer) {
-  auto reset_color = string_view("\x1b[0m");
-  buffer.append(reset_color.begin(), reset_color.end());
-}
-
-template <typename T> struct styled_arg : detail::view {
-  const T& value;
-  text_style style;
-  styled_arg(const T& v, text_style s) : value(v), style(s) {}
-};
-
-template <typename Char>
-void vformat_to(buffer<Char>& buf, const text_style& ts,
-                basic_string_view<Char> format_str,
-                basic_format_args<buffer_context<type_identity_t<Char>>> args) {
-  bool has_style = false;
-  if (ts.has_emphasis()) {
-    has_style = true;
-    auto emphasis = detail::make_emphasis<Char>(ts.get_emphasis());
-    buf.append(emphasis.begin(), emphasis.end());
-  }
-  if (ts.has_foreground()) {
-    has_style = true;
-    auto foreground = detail::make_foreground_color<Char>(ts.get_foreground());
-    buf.append(foreground.begin(), foreground.end());
-  }
-  if (ts.has_background()) {
-    has_style = true;
-    auto background = detail::make_background_color<Char>(ts.get_background());
-    buf.append(background.begin(), background.end());
-  }
-  detail::vformat_to(buf, format_str, args, {});
-  if (has_style) detail::reset_color<Char>(buf);
-}
-
-}  // namespace detail
-
-inline void vprint(std::FILE* f, const text_style& ts, string_view fmt,
-                   format_args args) {
-  // Legacy wide streams are not supported.
-  auto buf = memory_buffer();
-  detail::vformat_to(buf, ts, fmt, args);
-  if (detail::is_utf8()) {
-    detail::print(f, string_view(buf.begin(), buf.size()));
-    return;
-  }
-  buf.push_back('\0');
-  int result = std::fputs(buf.data(), f);
-  if (result < 0)
-    FMT_THROW(system_error(errno, FMT_STRING("cannot write to file")));
-}
-
-/**
-  \rst
-  Formats a string and prints it to the specified file stream using ANSI
-  escape sequences to specify text formatting.
-
-  **Example**::
-
-    fmt::print(fmt::emphasis::bold | fg(fmt::color::red),
-               "Elapsed time: {0:.2f} seconds", 1.23);
-  \endrst
- */
-template <typename S, typename... Args,
-          FMT_ENABLE_IF(detail::is_string<S>::value)>
-void print(std::FILE* f, const text_style& ts, const S& format_str,
-           const Args&... args) {
-  vprint(f, ts, format_str,
-         fmt::make_format_args<buffer_context<char_t<S>>>(args...));
-}
-
-/**
-  \rst
-  Formats a string and prints it to stdout using ANSI escape sequences to
-  specify text formatting.
-
-  **Example**::
-
-    fmt::print(fmt::emphasis::bold | fg(fmt::color::red),
-               "Elapsed time: {0:.2f} seconds", 1.23);
-  \endrst
- */
-template <typename S, typename... Args,
-          FMT_ENABLE_IF(detail::is_string<S>::value)>
-void print(const text_style& ts, const S& format_str, const Args&... args) {
-  return print(stdout, ts, format_str, args...);
-}
-
-template <typename S, typename Char = char_t<S>>
-inline std::basic_string<Char> vformat(
-    const text_style& ts, const S& format_str,
-    basic_format_args<buffer_context<type_identity_t<Char>>> args) {
-  basic_memory_buffer<Char> buf;
-  detail::vformat_to(buf, ts, detail::to_string_view(format_str), args);
-  return fmt::to_string(buf);
-}
-
-/**
-  \rst
-  Formats arguments and returns the result as a string using ANSI
-  escape sequences to specify text formatting.
-
-  **Example**::
-
-    #include <fmt/color.h>
-    std::string message = fmt::format(fmt::emphasis::bold | fg(fmt::color::red),
-                                      "The answer is {}", 42);
-  \endrst
-*/
-template <typename S, typename... Args, typename Char = char_t<S>>
-inline std::basic_string<Char> format(const text_style& ts, const S& format_str,
-                                      const Args&... args) {
-  return fmt::vformat(ts, detail::to_string_view(format_str),
-                      fmt::make_format_args<buffer_context<Char>>(args...));
-}
-
-/**
-  Formats a string with the given text_style and writes the output to ``out``.
- */
-template <typename OutputIt, typename Char,
-          FMT_ENABLE_IF(detail::is_output_iterator<OutputIt, Char>::value)>
-OutputIt vformat_to(
-    OutputIt out, const text_style& ts, basic_string_view<Char> format_str,
-    basic_format_args<buffer_context<type_identity_t<Char>>> args) {
-  auto&& buf = detail::get_buffer<Char>(out);
-  detail::vformat_to(buf, ts, format_str, args);
-  return detail::get_iterator(buf, out);
-}
-
-/**
-  \rst
-  Formats arguments with the given text_style, writes the result to the output
-  iterator ``out`` and returns the iterator past the end of the output range.
-
-  **Example**::
-
-    std::vector<char> out;
-    fmt::format_to(std::back_inserter(out),
-                   fmt::emphasis::bold | fg(fmt::color::red), "{}", 42);
-  \endrst
-*/
-template <typename OutputIt, typename S, typename... Args,
-          bool enable = detail::is_output_iterator<OutputIt, char_t<S>>::value&&
-              detail::is_string<S>::value>
-inline auto format_to(OutputIt out, const text_style& ts, const S& format_str,
-                      Args&&... args) ->
-    typename std::enable_if<enable, OutputIt>::type {
-  return vformat_to(out, ts, detail::to_string_view(format_str),
-                    fmt::make_format_args<buffer_context<char_t<S>>>(args...));
-}
-
-template <typename T, typename Char>
-struct formatter<detail::styled_arg<T>, Char> : formatter<T, Char> {
-  template <typename FormatContext>
-  auto format(const detail::styled_arg<T>& arg, FormatContext& ctx) const
-      -> decltype(ctx.out()) {
-    const auto& ts = arg.style;
-    const auto& value = arg.value;
-    auto out = ctx.out();
-
-    bool has_style = false;
-    if (ts.has_emphasis()) {
-      has_style = true;
-      auto emphasis = detail::make_emphasis<Char>(ts.get_emphasis());
-      out = std::copy(emphasis.begin(), emphasis.end(), out);
-    }
-    if (ts.has_foreground()) {
-      has_style = true;
-      auto foreground =
-          detail::make_foreground_color<Char>(ts.get_foreground());
-      out = std::copy(foreground.begin(), foreground.end(), out);
-    }
-    if (ts.has_background()) {
-      has_style = true;
-      auto background =
-          detail::make_background_color<Char>(ts.get_background());
-      out = std::copy(background.begin(), background.end(), out);
-    }
-    out = formatter<T, Char>::format(value, ctx);
-    if (has_style) {
-      auto reset_color = string_view("\x1b[0m");
-      out = std::copy(reset_color.begin(), reset_color.end(), out);
-    }
-    return out;
-  }
-};
-
-/**
-  \rst
-  Returns an argument that will be formatted using ANSI escape sequences,
-  to be used in a formatting function.
-
-  **Example**::
-
-    fmt::print("Elapsed time: {0:.2f} seconds",
-               fmt::styled(1.23, fmt::fg(fmt::color::green) |
-                                 fmt::bg(fmt::color::blue)));
-  \endrst
- */
-template <typename T>
-FMT_CONSTEXPR auto styled(const T& value, text_style ts)
-    -> detail::styled_arg<remove_cvref_t<T>> {
-  return detail::styled_arg<remove_cvref_t<T>>{value, ts};
-}
-
-FMT_END_EXPORT
-FMT_END_NAMESPACE
-
-#endif  // FMT_COLOR_H_
diff --git a/lib/fmt/include/fmt-vt/compile.h b/lib/fmt/include/fmt-vt/compile.h
deleted file mode 100644
index a4c7e49563..0000000000
--- a/lib/fmt/include/fmt-vt/compile.h
+++ /dev/null
@@ -1,534 +0,0 @@
-// Formatting library for C++ - experimental format string compilation
-//
-// Copyright (c) 2012 - present, Victor Zverovich and fmt contributors
-// All rights reserved.
-//
-// For the license information refer to format.h.
-
-#ifndef FMT_COMPILE_H_
-#define FMT_COMPILE_H_
-
-#include "format.h"
-
-FMT_BEGIN_NAMESPACE
-namespace detail {
-
-template <typename Char, typename InputIt>
-FMT_CONSTEXPR inline counting_iterator copy_str(InputIt begin, InputIt end,
-                                                counting_iterator it) {
-  return it + (end - begin);
-}
-
-// A compile-time string which is compiled into fast formatting code.
-class compiled_string {};
-
-template <typename S>
-struct is_compiled_string : std::is_base_of<compiled_string, S> {};
-
-/**
-  \rst
-  Converts a string literal *s* into a format string that will be parsed at
-  compile time and converted into efficient formatting code. Requires C++17
-  ``constexpr if`` compiler support.
-
-  **Example**::
-
-    // Converts 42 into std::string using the most efficient method and no
-    // runtime format string processing.
-    std::string s = fmt::format(FMT_COMPILE("{}"), 42);
-  \endrst
- */
-#if defined(__cpp_if_constexpr) && defined(__cpp_return_type_deduction)
-#  define FMT_COMPILE(s) \
-    FMT_STRING_IMPL(s, fmt::detail::compiled_string, explicit)
-#else
-#  define FMT_COMPILE(s) FMT_STRING(s)
-#endif
-
-#if FMT_USE_NONTYPE_TEMPLATE_ARGS
-template <typename Char, size_t N,
-          fmt::detail_exported::fixed_string<Char, N> Str>
-struct udl_compiled_string : compiled_string {
-  using char_type = Char;
-  explicit constexpr operator basic_string_view<char_type>() const {
-    return {Str.data, N - 1};
-  }
-};
-#endif
-
-template <typename T, typename... Tail>
-const T& first(const T& value, const Tail&...) {
-  return value;
-}
-
-#if defined(__cpp_if_constexpr) && defined(__cpp_return_type_deduction)
-template <typename... Args> struct type_list {};
-
-// Returns a reference to the argument at index N from [first, rest...].
-template <int N, typename T, typename... Args>
-constexpr const auto& get([[maybe_unused]] const T& first,
-                          [[maybe_unused]] const Args&... rest) {
-  static_assert(N < 1 + sizeof...(Args), "index is out of bounds");
-  if constexpr (N == 0)
-    return first;
-  else
-    return detail::get<N - 1>(rest...);
-}
-
-template <typename Char, typename... Args>
-constexpr int get_arg_index_by_name(basic_string_view<Char> name,
-                                    type_list<Args...>) {
-  return get_arg_index_by_name<Args...>(name);
-}
-
-template <int N, typename> struct get_type_impl;
-
-template <int N, typename... Args> struct get_type_impl<N, type_list<Args...>> {
-  using type =
-      remove_cvref_t<decltype(detail::get<N>(std::declval<Args>()...))>;
-};
-
-template <int N, typename T>
-using get_type = typename get_type_impl<N, T>::type;
-
-template <typename T> struct is_compiled_format : std::false_type {};
-
-template <typename Char> struct text {
-  basic_string_view<Char> data;
-  using char_type = Char;
-
-  template <typename OutputIt, typename... Args>
-  constexpr OutputIt format(OutputIt out, const Args&...) const {
-    return write<Char>(out, data);
-  }
-};
-
-template <typename Char>
-struct is_compiled_format<text<Char>> : std::true_type {};
-
-template <typename Char>
-constexpr text<Char> make_text(basic_string_view<Char> s, size_t pos,
-                               size_t size) {
-  return {{&s[pos], size}};
-}
-
-template <typename Char> struct code_unit {
-  Char value;
-  using char_type = Char;
-
-  template <typename OutputIt, typename... Args>
-  constexpr OutputIt format(OutputIt out, const Args&...) const {
-    *out++ = value;
-    return out;
-  }
-};
-
-// This ensures that the argument type is convertible to `const T&`.
-template <typename T, int N, typename... Args>
-constexpr const T& get_arg_checked(const Args&... args) {
-  const auto& arg = detail::get<N>(args...);
-  if constexpr (detail::is_named_arg<remove_cvref_t<decltype(arg)>>()) {
-    return arg.value;
-  } else {
-    return arg;
-  }
-}
-
-template <typename Char>
-struct is_compiled_format<code_unit<Char>> : std::true_type {};
-
-// A replacement field that refers to argument N.
-template <typename Char, typename T, int N> struct field {
-  using char_type = Char;
-
-  template <typename OutputIt, typename... Args>
-  constexpr OutputIt format(OutputIt out, const Args&... args) const {
-    const T& arg = get_arg_checked<T, N>(args...);
-    if constexpr (std::is_convertible_v<T, basic_string_view<Char>>) {
-      auto s = basic_string_view<Char>(arg);
-      return copy_str<Char>(s.begin(), s.end(), out);
-    }
-    return write<Char>(out, arg);
-  }
-};
-
-template <typename Char, typename T, int N>
-struct is_compiled_format<field<Char, T, N>> : std::true_type {};
-
-// A replacement field that refers to argument with name.
-template <typename Char> struct runtime_named_field {
-  using char_type = Char;
-  basic_string_view<Char> name;
-
-  template <typename OutputIt, typename T>
-  constexpr static bool try_format_argument(
-      OutputIt& out,
-      // [[maybe_unused]] due to unused-but-set-parameter warning in GCC 7,8,9
-      [[maybe_unused]] basic_string_view<Char> arg_name, const T& arg) {
-    if constexpr (is_named_arg<typename std::remove_cv<T>::type>::value) {
-      if (arg_name == arg.name) {
-        out = write<Char>(out, arg.value);
-        return true;
-      }
-    }
-    return false;
-  }
-
-  template <typename OutputIt, typename... Args>
-  constexpr OutputIt format(OutputIt out, const Args&... args) const {
-    bool found = (try_format_argument(out, name, args) || ...);
-    if (!found) {
-      FMT_THROW(format_error("argument with specified name is not found"));
-    }
-    return out;
-  }
-};
-
-template <typename Char>
-struct is_compiled_format<runtime_named_field<Char>> : std::true_type {};
-
-// A replacement field that refers to argument N and has format specifiers.
-template <typename Char, typename T, int N> struct spec_field {
-  using char_type = Char;
-  formatter<T, Char> fmt;
-
-  template <typename OutputIt, typename... Args>
-  constexpr FMT_INLINE OutputIt format(OutputIt out,
-                                       const Args&... args) const {
-    const auto& vargs =
-        fmt::make_format_args<basic_format_context<OutputIt, Char>>(args...);
-    basic_format_context<OutputIt, Char> ctx(out, vargs);
-    return fmt.format(get_arg_checked<T, N>(args...), ctx);
-  }
-};
-
-template <typename Char, typename T, int N>
-struct is_compiled_format<spec_field<Char, T, N>> : std::true_type {};
-
-template <typename L, typename R> struct concat {
-  L lhs;
-  R rhs;
-  using char_type = typename L::char_type;
-
-  template <typename OutputIt, typename... Args>
-  constexpr OutputIt format(OutputIt out, const Args&... args) const {
-    out = lhs.format(out, args...);
-    return rhs.format(out, args...);
-  }
-};
-
-template <typename L, typename R>
-struct is_compiled_format<concat<L, R>> : std::true_type {};
-
-template <typename L, typename R>
-constexpr concat<L, R> make_concat(L lhs, R rhs) {
-  return {lhs, rhs};
-}
-
-struct unknown_format {};
-
-template <typename Char>
-constexpr size_t parse_text(basic_string_view<Char> str, size_t pos) {
-  for (size_t size = str.size(); pos != size; ++pos) {
-    if (str[pos] == '{' || str[pos] == '}') break;
-  }
-  return pos;
-}
-
-template <typename Args, size_t POS, int ID, typename S>
-constexpr auto compile_format_string(S format_str);
-
-template <typename Args, size_t POS, int ID, typename T, typename S>
-constexpr auto parse_tail(T head, S format_str) {
-  if constexpr (POS !=
-                basic_string_view<typename S::char_type>(format_str).size()) {
-    constexpr auto tail = compile_format_string<Args, POS, ID>(format_str);
-    if constexpr (std::is_same<remove_cvref_t<decltype(tail)>,
-                               unknown_format>())
-      return tail;
-    else
-      return make_concat(head, tail);
-  } else {
-    return head;
-  }
-}
-
-template <typename T, typename Char> struct parse_specs_result {
-  formatter<T, Char> fmt;
-  size_t end;
-  int next_arg_id;
-};
-
-enum { manual_indexing_id = -1 };
-
-template <typename T, typename Char>
-constexpr parse_specs_result<T, Char> parse_specs(basic_string_view<Char> str,
-                                                  size_t pos, int next_arg_id) {
-  str.remove_prefix(pos);
-  auto ctx =
-      compile_parse_context<Char>(str, max_value<int>(), nullptr, next_arg_id);
-  auto f = formatter<T, Char>();
-  auto end = f.parse(ctx);
-  return {f, pos + fmt::detail::to_unsigned(end - str.data()),
-          next_arg_id == 0 ? manual_indexing_id : ctx.next_arg_id()};
-}
-
-template <typename Char> struct arg_id_handler {
-  arg_ref<Char> arg_id;
-
-  constexpr int on_auto() {
-    FMT_ASSERT(false, "handler cannot be used with automatic indexing");
-    return 0;
-  }
-  constexpr int on_index(int id) {
-    arg_id = arg_ref<Char>(id);
-    return 0;
-  }
-  constexpr int on_name(basic_string_view<Char> id) {
-    arg_id = arg_ref<Char>(id);
-    return 0;
-  }
-};
-
-template <typename Char> struct parse_arg_id_result {
-  arg_ref<Char> arg_id;
-  const Char* arg_id_end;
-};
-
-template <int ID, typename Char>
-constexpr auto parse_arg_id(const Char* begin, const Char* end) {
-  auto handler = arg_id_handler<Char>{arg_ref<Char>{}};
-  auto arg_id_end = parse_arg_id(begin, end, handler);
-  return parse_arg_id_result<Char>{handler.arg_id, arg_id_end};
-}
-
-template <typename T, typename Enable = void> struct field_type {
-  using type = remove_cvref_t<T>;
-};
-
-template <typename T>
-struct field_type<T, enable_if_t<detail::is_named_arg<T>::value>> {
-  using type = remove_cvref_t<decltype(T::value)>;
-};
-
-template <typename T, typename Args, size_t END_POS, int ARG_INDEX, int NEXT_ID,
-          typename S>
-constexpr auto parse_replacement_field_then_tail(S format_str) {
-  using char_type = typename S::char_type;
-  constexpr auto str = basic_string_view<char_type>(format_str);
-  constexpr char_type c = END_POS != str.size() ? str[END_POS] : char_type();
-  if constexpr (c == '}') {
-    return parse_tail<Args, END_POS + 1, NEXT_ID>(
-        field<char_type, typename field_type<T>::type, ARG_INDEX>(),
-        format_str);
-  } else if constexpr (c != ':') {
-    FMT_THROW(format_error("expected ':'"));
-  } else {
-    constexpr auto result = parse_specs<typename field_type<T>::type>(
-        str, END_POS + 1, NEXT_ID == manual_indexing_id ? 0 : NEXT_ID);
-    if constexpr (result.end >= str.size() || str[result.end] != '}') {
-      FMT_THROW(format_error("expected '}'"));
-      return 0;
-    } else {
-      return parse_tail<Args, result.end + 1, result.next_arg_id>(
-          spec_field<char_type, typename field_type<T>::type, ARG_INDEX>{
-              result.fmt},
-          format_str);
-    }
-  }
-}
-
-// Compiles a non-empty format string and returns the compiled representation
-// or unknown_format() on unrecognized input.
-template <typename Args, size_t POS, int ID, typename S>
-constexpr auto compile_format_string(S format_str) {
-  using char_type = typename S::char_type;
-  constexpr auto str = basic_string_view<char_type>(format_str);
-  if constexpr (str[POS] == '{') {
-    if constexpr (POS + 1 == str.size())
-      FMT_THROW(format_error("unmatched '{' in format string"));
-    if constexpr (str[POS + 1] == '{') {
-      return parse_tail<Args, POS + 2, ID>(make_text(str, POS, 1), format_str);
-    } else if constexpr (str[POS + 1] == '}' || str[POS + 1] == ':') {
-      static_assert(ID != manual_indexing_id,
-                    "cannot switch from manual to automatic argument indexing");
-      constexpr auto next_id =
-          ID != manual_indexing_id ? ID + 1 : manual_indexing_id;
-      return parse_replacement_field_then_tail<get_type<ID, Args>, Args,
-                                               POS + 1, ID, next_id>(
-          format_str);
-    } else {
-      constexpr auto arg_id_result =
-          parse_arg_id<ID>(str.data() + POS + 1, str.data() + str.size());
-      constexpr auto arg_id_end_pos = arg_id_result.arg_id_end - str.data();
-      constexpr char_type c =
-          arg_id_end_pos != str.size() ? str[arg_id_end_pos] : char_type();
-      static_assert(c == '}' || c == ':', "missing '}' in format string");
-      if constexpr (arg_id_result.arg_id.kind == arg_id_kind::index) {
-        static_assert(
-            ID == manual_indexing_id || ID == 0,
-            "cannot switch from automatic to manual argument indexing");
-        constexpr auto arg_index = arg_id_result.arg_id.val.index;
-        return parse_replacement_field_then_tail<get_type<arg_index, Args>,
-                                                 Args, arg_id_end_pos,
-                                                 arg_index, manual_indexing_id>(
-            format_str);
-      } else if constexpr (arg_id_result.arg_id.kind == arg_id_kind::name) {
-        constexpr auto arg_index =
-            get_arg_index_by_name(arg_id_result.arg_id.val.name, Args{});
-        if constexpr (arg_index >= 0) {
-          constexpr auto next_id =
-              ID != manual_indexing_id ? ID + 1 : manual_indexing_id;
-          return parse_replacement_field_then_tail<
-              decltype(get_type<arg_index, Args>::value), Args, arg_id_end_pos,
-              arg_index, next_id>(format_str);
-        } else if constexpr (c == '}') {
-          return parse_tail<Args, arg_id_end_pos + 1, ID>(
-              runtime_named_field<char_type>{arg_id_result.arg_id.val.name},
-              format_str);
-        } else if constexpr (c == ':') {
-          return unknown_format();  // no type info for specs parsing
-        }
-      }
-    }
-  } else if constexpr (str[POS] == '}') {
-    if constexpr (POS + 1 == str.size())
-      FMT_THROW(format_error("unmatched '}' in format string"));
-    return parse_tail<Args, POS + 2, ID>(make_text(str, POS, 1), format_str);
-  } else {
-    constexpr auto end = parse_text(str, POS + 1);
-    if constexpr (end - POS > 1) {
-      return parse_tail<Args, end, ID>(make_text(str, POS, end - POS),
-                                       format_str);
-    } else {
-      return parse_tail<Args, end, ID>(code_unit<char_type>{str[POS]},
-                                       format_str);
-    }
-  }
-}
-
-template <typename... Args, typename S,
-          FMT_ENABLE_IF(detail::is_compiled_string<S>::value)>
-constexpr auto compile(S format_str) {
-  constexpr auto str = basic_string_view<typename S::char_type>(format_str);
-  if constexpr (str.size() == 0) {
-    return detail::make_text(str, 0, 0);
-  } else {
-    constexpr auto result =
-        detail::compile_format_string<detail::type_list<Args...>, 0, 0>(
-            format_str);
-    return result;
-  }
-}
-#endif  // defined(__cpp_if_constexpr) && defined(__cpp_return_type_deduction)
-}  // namespace detail
-
-FMT_BEGIN_EXPORT
-
-#if defined(__cpp_if_constexpr) && defined(__cpp_return_type_deduction)
-
-template <typename CompiledFormat, typename... Args,
-          typename Char = typename CompiledFormat::char_type,
-          FMT_ENABLE_IF(detail::is_compiled_format<CompiledFormat>::value)>
-FMT_INLINE std::basic_string<Char> format(const CompiledFormat& cf,
-                                          const Args&... args) {
-  auto s = std::basic_string<Char>();
-  cf.format(std::back_inserter(s), args...);
-  return s;
-}
-
-template <typename OutputIt, typename CompiledFormat, typename... Args,
-          FMT_ENABLE_IF(detail::is_compiled_format<CompiledFormat>::value)>
-constexpr FMT_INLINE OutputIt format_to(OutputIt out, const CompiledFormat& cf,
-                                        const Args&... args) {
-  return cf.format(out, args...);
-}
-
-template <typename S, typename... Args,
-          FMT_ENABLE_IF(detail::is_compiled_string<S>::value)>
-FMT_INLINE std::basic_string<typename S::char_type> format(const S&,
-                                                           Args&&... args) {
-  if constexpr (std::is_same<typename S::char_type, char>::value) {
-    constexpr auto str = basic_string_view<typename S::char_type>(S());
-    if constexpr (str.size() == 2 && str[0] == '{' && str[1] == '}') {
-      const auto& first = detail::first(args...);
-      if constexpr (detail::is_named_arg<
-                        remove_cvref_t<decltype(first)>>::value) {
-        return fmt::to_string(first.value);
-      } else {
-        return fmt::to_string(first);
-      }
-    }
-  }
-  constexpr auto compiled = detail::compile<Args...>(S());
-  if constexpr (std::is_same<remove_cvref_t<decltype(compiled)>,
-                             detail::unknown_format>()) {
-    return fmt::format(
-        static_cast<basic_string_view<typename S::char_type>>(S()),
-        std::forward<Args>(args)...);
-  } else {
-    return fmt::format(compiled, std::forward<Args>(args)...);
-  }
-}
-
-template <typename OutputIt, typename S, typename... Args,
-          FMT_ENABLE_IF(detail::is_compiled_string<S>::value)>
-FMT_CONSTEXPR OutputIt format_to(OutputIt out, const S&, Args&&... args) {
-  constexpr auto compiled = detail::compile<Args...>(S());
-  if constexpr (std::is_same<remove_cvref_t<decltype(compiled)>,
-                             detail::unknown_format>()) {
-    return fmt::format_to(
-        out, static_cast<basic_string_view<typename S::char_type>>(S()),
-        std::forward<Args>(args)...);
-  } else {
-    return fmt::format_to(out, compiled, std::forward<Args>(args)...);
-  }
-}
-#endif
-
-template <typename OutputIt, typename S, typename... Args,
-          FMT_ENABLE_IF(detail::is_compiled_string<S>::value)>
-format_to_n_result<OutputIt> format_to_n(OutputIt out, size_t n,
-                                         const S& format_str, Args&&... args) {
-  using traits = detail::fixed_buffer_traits;
-  auto buf = detail::iterator_buffer<OutputIt, char, traits>(out, n);
-  format_to(std::back_inserter(buf), format_str, std::forward<Args>(args)...);
-  return {buf.out(), buf.count()};
-}
-
-template <typename S, typename... Args,
-          FMT_ENABLE_IF(detail::is_compiled_string<S>::value)>
-FMT_CONSTEXPR20 size_t formatted_size(const S& format_str,
-                                      const Args&... args) {
-  return fmt::format_to(detail::counting_iterator(), format_str, args...)
-      .count();
-}
-
-template <typename S, typename... Args,
-          FMT_ENABLE_IF(detail::is_compiled_string<S>::value)>
-void print(std::FILE* f, const S& format_str, const Args&... args) {
-  memory_buffer buffer;
-  fmt::format_to(std::back_inserter(buffer), format_str, args...);
-  detail::print(f, {buffer.data(), buffer.size()});
-}
-
-template <typename S, typename... Args,
-          FMT_ENABLE_IF(detail::is_compiled_string<S>::value)>
-void print(const S& format_str, const Args&... args) {
-  print(stdout, format_str, args...);
-}
-
-#if FMT_USE_NONTYPE_TEMPLATE_ARGS
-inline namespace literals {
-template <detail_exported::fixed_string Str> constexpr auto operator""_cf() {
-  using char_t = remove_cvref_t<decltype(Str.data[0])>;
-  return detail::udl_compiled_string<char_t, sizeof(Str.data) / sizeof(char_t),
-                                     Str>();
-}
-}  // namespace literals
-#endif
-
-FMT_END_EXPORT
-FMT_END_NAMESPACE
-
-#endif  // FMT_COMPILE_H_
diff --git a/lib/fmt/include/fmt-vt/core.h b/lib/fmt/include/fmt-vt/core.h
index f7432fa1c1..9514ccd181 100644
--- a/lib/fmt/include/fmt-vt/core.h
+++ b/lib/fmt/include/fmt-vt/core.h
@@ -1,4 +1,4 @@
-// Formatting library for C++ - the core API for char/UTF-8
+// Formatting library for C++ - the core API
 //
 // Copyright (c) 2012 - present, Victor Zverovich
 // All rights reserved.
@@ -8,60 +8,54 @@
 #ifndef FMT_CORE_H_
 #define FMT_CORE_H_
 
-#include <cstddef>  // std::byte
-#include <cstdio>   // std::FILE
-#include <cstring>  // std::strlen
+#include <cstdio>  // std::FILE
+#include <cstring>
+#include <functional>
 #include <iterator>
-#include <limits>
-#include <memory>  // std::addressof
+#include <memory>
 #include <string>
 #include <type_traits>
+#include <vector>
 
 // The fmt library version in the form major * 10000 + minor * 100 + patch.
-#define FMT_VERSION 100101
+#define FMT_VERSION 70103
 
-#if defined(__clang__) && !defined(__ibmxl__)
+#ifdef __clang__
 #  define FMT_CLANG_VERSION (__clang_major__ * 100 + __clang_minor__)
 #else
 #  define FMT_CLANG_VERSION 0
 #endif
 
-#if defined(__GNUC__) && !defined(__clang__) && !defined(__INTEL_COMPILER) && \
-    !defined(__NVCOMPILER)
+#if defined(__GNUC__) && !defined(__clang__)
 #  define FMT_GCC_VERSION (__GNUC__ * 100 + __GNUC_MINOR__)
 #else
 #  define FMT_GCC_VERSION 0
 #endif
 
-#ifndef FMT_GCC_PRAGMA
-// Workaround _Pragma bug https://gcc.gnu.org/bugzilla/show_bug.cgi?id=59884.
-#  if FMT_GCC_VERSION >= 504
-#    define FMT_GCC_PRAGMA(arg) _Pragma(arg)
-#  else
-#    define FMT_GCC_PRAGMA(arg)
-#  endif
-#endif
-
-#ifdef __ICL
-#  define FMT_ICC_VERSION __ICL
-#elif defined(__INTEL_COMPILER)
+#if defined(__INTEL_COMPILER)
 #  define FMT_ICC_VERSION __INTEL_COMPILER
 #else
 #  define FMT_ICC_VERSION 0
 #endif
 
-#ifdef _MSC_VER
-#  define FMT_MSC_VERSION _MSC_VER
-#  define FMT_MSC_WARNING(...) __pragma(warning(__VA_ARGS__))
+#if __cplusplus >= 201103L || defined(__GXX_EXPERIMENTAL_CXX0X__)
+#  define FMT_HAS_GXX_CXX11 FMT_GCC_VERSION
+#else
+#  define FMT_HAS_GXX_CXX11 0
+#endif
+
+#ifdef __NVCC__
+#  define FMT_NVCC __NVCC__
 #else
-#  define FMT_MSC_VERSION 0
-#  define FMT_MSC_WARNING(...)
+#  define FMT_NVCC 0
 #endif
 
-#ifdef _MSVC_LANG
-#  define FMT_CPLUSPLUS _MSVC_LANG
+#ifdef _MSC_VER
+#  define FMT_MSC_VER _MSC_VER
+#  define FMT_SUPPRESS_MSC_WARNING(n) __pragma(warning(suppress : n))
 #else
-#  define FMT_CPLUSPLUS __cplusplus
+#  define FMT_MSC_VER 0
+#  define FMT_SUPPRESS_MSC_WARNING(n)
 #endif
 
 #ifdef __has_feature
@@ -70,7 +64,8 @@
 #  define FMT_HAS_FEATURE(x) 0
 #endif
 
-#if defined(__has_include) || FMT_ICC_VERSION >= 1600 || FMT_MSC_VERSION > 1900
+#if defined(__has_include) && !defined(__INTELLISENSE__) && \
+    (!FMT_ICC_VERSION || FMT_ICC_VERSION >= 1600)
 #  define FMT_HAS_INCLUDE(x) __has_include(x)
 #else
 #  define FMT_HAS_INCLUDE(x) 0
@@ -83,78 +78,98 @@
 #endif
 
 #define FMT_HAS_CPP14_ATTRIBUTE(attribute) \
-  (FMT_CPLUSPLUS >= 201402L && FMT_HAS_CPP_ATTRIBUTE(attribute))
+  (__cplusplus >= 201402L && FMT_HAS_CPP_ATTRIBUTE(attribute))
 
 #define FMT_HAS_CPP17_ATTRIBUTE(attribute) \
-  (FMT_CPLUSPLUS >= 201703L && FMT_HAS_CPP_ATTRIBUTE(attribute))
+  (__cplusplus >= 201703L && FMT_HAS_CPP_ATTRIBUTE(attribute))
 
 // Check if relaxed C++14 constexpr is supported.
 // GCC doesn't allow throw in constexpr until version 6 (bug 67371).
 #ifndef FMT_USE_CONSTEXPR
-#  if (FMT_HAS_FEATURE(cxx_relaxed_constexpr) || FMT_MSC_VERSION >= 1912 || \
-       (FMT_GCC_VERSION >= 600 && FMT_CPLUSPLUS >= 201402L)) &&             \
-      !FMT_ICC_VERSION && (!defined(__NVCC__) || FMT_CPLUSPLUS >= 202002L)
-#    define FMT_USE_CONSTEXPR 1
-#  else
-#    define FMT_USE_CONSTEXPR 0
-#  endif
+#  define FMT_USE_CONSTEXPR                                           \
+    (FMT_HAS_FEATURE(cxx_relaxed_constexpr) || FMT_MSC_VER >= 1910 || \
+     (FMT_GCC_VERSION >= 600 && __cplusplus >= 201402L)) &&           \
+        !FMT_NVCC && !FMT_ICC_VERSION
 #endif
 #if FMT_USE_CONSTEXPR
 #  define FMT_CONSTEXPR constexpr
+#  define FMT_CONSTEXPR_DECL constexpr
 #else
-#  define FMT_CONSTEXPR
-#endif
-
-#if ((FMT_CPLUSPLUS >= 202002L) &&                            \
-     (!defined(_GLIBCXX_RELEASE) || _GLIBCXX_RELEASE > 9)) || \
-    (FMT_CPLUSPLUS >= 201709L && FMT_GCC_VERSION >= 1002)
-#  define FMT_CONSTEXPR20 constexpr
-#else
-#  define FMT_CONSTEXPR20
+#  define FMT_CONSTEXPR inline
+#  define FMT_CONSTEXPR_DECL
 #endif
 
-// Check if constexpr std::char_traits<>::{compare,length} are supported.
-#if defined(__GLIBCXX__)
-#  if FMT_CPLUSPLUS >= 201703L && defined(_GLIBCXX_RELEASE) && \
-      _GLIBCXX_RELEASE >= 7  // GCC 7+ libstdc++ has _GLIBCXX_RELEASE.
-#    define FMT_CONSTEXPR_CHAR_TRAITS constexpr
+#ifndef FMT_OVERRIDE
+#  if FMT_HAS_FEATURE(cxx_override_control) || \
+      (FMT_GCC_VERSION >= 408 && FMT_HAS_GXX_CXX11) || FMT_MSC_VER >= 1900
+#    define FMT_OVERRIDE override
+#  else
+#    define FMT_OVERRIDE
 #  endif
-#elif defined(_LIBCPP_VERSION) && FMT_CPLUSPLUS >= 201703L && \
-    _LIBCPP_VERSION >= 4000
-#  define FMT_CONSTEXPR_CHAR_TRAITS constexpr
-#elif FMT_MSC_VERSION >= 1914 && FMT_CPLUSPLUS >= 201703L
-#  define FMT_CONSTEXPR_CHAR_TRAITS constexpr
-#endif
-#ifndef FMT_CONSTEXPR_CHAR_TRAITS
-#  define FMT_CONSTEXPR_CHAR_TRAITS
 #endif
 
 // Check if exceptions are disabled.
 #ifndef FMT_EXCEPTIONS
 #  if (defined(__GNUC__) && !defined(__EXCEPTIONS)) || \
-      (FMT_MSC_VERSION && !_HAS_EXCEPTIONS)
+      FMT_MSC_VER && !_HAS_EXCEPTIONS
 #    define FMT_EXCEPTIONS 0
 #  else
 #    define FMT_EXCEPTIONS 1
 #  endif
 #endif
 
-// Disable [[noreturn]] on MSVC/NVCC because of bogus unreachable code warnings.
-#if FMT_EXCEPTIONS && FMT_HAS_CPP_ATTRIBUTE(noreturn) && !FMT_MSC_VERSION && \
-    !defined(__NVCC__)
+// Define FMT_USE_NOEXCEPT to make fmt use noexcept (C++11 feature).
+#ifndef FMT_USE_NOEXCEPT
+#  define FMT_USE_NOEXCEPT 0
+#endif
+
+#if FMT_USE_NOEXCEPT || FMT_HAS_FEATURE(cxx_noexcept) || \
+    (FMT_GCC_VERSION >= 408 && FMT_HAS_GXX_CXX11) || FMT_MSC_VER >= 1900
+#  define FMT_DETECTED_NOEXCEPT noexcept
+#  define FMT_HAS_CXX11_NOEXCEPT 1
+#else
+#  define FMT_DETECTED_NOEXCEPT throw()
+#  define FMT_HAS_CXX11_NOEXCEPT 0
+#endif
+
+#ifndef FMT_NOEXCEPT
+#  if FMT_EXCEPTIONS || FMT_HAS_CXX11_NOEXCEPT
+#    define FMT_NOEXCEPT FMT_DETECTED_NOEXCEPT
+#  else
+#    define FMT_NOEXCEPT
+#  endif
+#endif
+
+// [[noreturn]] is disabled on MSVC and NVCC because of bogus unreachable code
+// warnings.
+#if FMT_EXCEPTIONS && FMT_HAS_CPP_ATTRIBUTE(noreturn) && !FMT_MSC_VER && \
+    !FMT_NVCC
 #  define FMT_NORETURN [[noreturn]]
 #else
 #  define FMT_NORETURN
 #endif
 
-#ifndef FMT_NODISCARD
-#  if FMT_HAS_CPP17_ATTRIBUTE(nodiscard)
-#    define FMT_NODISCARD [[nodiscard]]
+#ifndef FMT_DEPRECATED
+#  if FMT_HAS_CPP14_ATTRIBUTE(deprecated) || FMT_MSC_VER >= 1900
+#    define FMT_DEPRECATED [[deprecated]]
 #  else
-#    define FMT_NODISCARD
+#    if (defined(__GNUC__) && !defined(__LCC__)) || defined(__clang__)
+#      define FMT_DEPRECATED __attribute__((deprecated))
+#    elif FMT_MSC_VER
+#      define FMT_DEPRECATED __declspec(deprecated)
+#    else
+#      define FMT_DEPRECATED /* deprecated */
+#    endif
 #  endif
 #endif
 
+// Workaround broken [[deprecated]] in the Intel, PGI and NVCC compilers.
+#if FMT_ICC_VERSION || defined(__PGI) || FMT_NVCC
+#  define FMT_DEPRECATED_ALIAS
+#else
+#  define FMT_DEPRECATED_ALIAS FMT_DEPRECATED
+#endif
+
 #ifndef FMT_INLINE
 #  if FMT_GCC_VERSION || FMT_CLANG_VERSION
 #    define FMT_INLINE inline __attribute__((always_inline))
@@ -163,102 +178,86 @@
 #  endif
 #endif
 
-#ifdef _MSC_VER
-#  define FMT_UNCHECKED_ITERATOR(It) \
-    using _Unchecked_type = It  // Mark iterator as checked.
-#else
-#  define FMT_UNCHECKED_ITERATOR(It) using unchecked_type = It
+#ifndef FMT_USE_INLINE_NAMESPACES
+#  if FMT_HAS_FEATURE(cxx_inline_namespaces) || FMT_GCC_VERSION >= 404 || \
+      (FMT_MSC_VER >= 1900 && !_MANAGED)
+#    define FMT_USE_INLINE_NAMESPACES 1
+#  else
+#    define FMT_USE_INLINE_NAMESPACES 0
+#  endif
 #endif
 
 #ifndef FMT_BEGIN_NAMESPACE
+#  if FMT_USE_INLINE_NAMESPACES
+#    define FMT_INLINE_NAMESPACE inline namespace
+#    define FMT_END_NAMESPACE \
+      }                       \
+      }
+#  else
+#    define FMT_INLINE_NAMESPACE namespace
+#    define FMT_END_NAMESPACE \
+      }                       \
+      using namespace vt;     \
+      }
+#  endif
 #  define FMT_BEGIN_NAMESPACE \
     namespace fmt {           \
-    inline namespace v10 {    \
-    inline namespace vt {
-#  define FMT_END_NAMESPACE \
-    }                       \
-    }                       \
-    }
-#endif
-
-#ifndef FMT_EXPORT
-#  define FMT_EXPORT
-#  define FMT_BEGIN_EXPORT
-#  define FMT_END_EXPORT
-#endif
-
-#if FMT_GCC_VERSION || FMT_CLANG_VERSION
-#  define FMT_VISIBILITY(value) __attribute__((visibility(value)))
-#else
-#  define FMT_VISIBILITY(value)
+    FMT_INLINE_NAMESPACE vt {
 #endif
 
 #if !defined(FMT_HEADER_ONLY) && defined(_WIN32)
-#  if defined(FMT_LIB_EXPORT)
+#  define FMT_CLASS_API FMT_SUPPRESS_MSC_WARNING(4275)
+#  ifdef FMT_EXPORT
 #    define FMT_API __declspec(dllexport)
+#    define FMT_EXTERN_TEMPLATE_API FMT_API
+#    define FMT_EXPORTED
 #  elif defined(FMT_SHARED)
 #    define FMT_API __declspec(dllimport)
+#    define FMT_EXTERN_TEMPLATE_API FMT_API
 #  endif
-#elif defined(FMT_LIB_EXPORT) || defined(FMT_SHARED)
-#  define FMT_API FMT_VISIBILITY("default")
+#else
+#  define FMT_CLASS_API
 #endif
 #ifndef FMT_API
 #  define FMT_API
 #endif
+#ifndef FMT_EXTERN_TEMPLATE_API
+#  define FMT_EXTERN_TEMPLATE_API
+#endif
+#ifndef FMT_INSTANTIATION_DEF_API
+#  define FMT_INSTANTIATION_DEF_API FMT_API
+#endif
+
+#ifndef FMT_HEADER_ONLY
+#  define FMT_EXTERN extern
+#else
+#  define FMT_EXTERN
+#endif
 
 // libc++ supports string_view in pre-c++17.
-#if FMT_HAS_INCLUDE(<string_view>) && \
-    (FMT_CPLUSPLUS >= 201703L || defined(_LIBCPP_VERSION))
+#if (FMT_HAS_INCLUDE(<string_view>) &&                       \
+     (__cplusplus > 201402L || defined(_LIBCPP_VERSION))) || \
+    (defined(_MSVC_LANG) && _MSVC_LANG > 201402L && _MSC_VER >= 1910)
 #  include <string_view>
 #  define FMT_USE_STRING_VIEW
-#elif FMT_HAS_INCLUDE("experimental/string_view") && FMT_CPLUSPLUS >= 201402L
+#elif FMT_HAS_INCLUDE("experimental/string_view") && __cplusplus >= 201402L
 #  include <experimental/string_view>
 #  define FMT_USE_EXPERIMENTAL_STRING_VIEW
 #endif
 
 #ifndef FMT_UNICODE
-#  define FMT_UNICODE !FMT_MSC_VERSION
+#  define FMT_UNICODE !FMT_MSC_VER
 #endif
-
-#ifndef FMT_CONSTEVAL
-#  if ((FMT_GCC_VERSION >= 1000 || FMT_CLANG_VERSION >= 1101) && \
-       (!defined(__apple_build_version__) ||                     \
-        __apple_build_version__ >= 14000029L) &&                 \
-       FMT_CPLUSPLUS >= 202002L) ||                              \
-      (defined(__cpp_consteval) &&                               \
-       (!FMT_MSC_VERSION || _MSC_FULL_VER >= 193030704))
-// consteval is broken in MSVC before VS2022 and Apple clang before 14.
-#    define FMT_CONSTEVAL consteval
-#    define FMT_HAS_CONSTEVAL
-#  else
-#    define FMT_CONSTEVAL
-#  endif
-#endif
-
-#ifndef FMT_USE_NONTYPE_TEMPLATE_ARGS
-#  if defined(__cpp_nontype_template_args) &&                  \
-      ((FMT_GCC_VERSION >= 903 && FMT_CPLUSPLUS >= 201709L) || \
-       __cpp_nontype_template_args >= 201911L) &&              \
-      !defined(__NVCOMPILER) && !defined(__LCC__)
-#    define FMT_USE_NONTYPE_TEMPLATE_ARGS 1
-#  else
-#    define FMT_USE_NONTYPE_TEMPLATE_ARGS 0
-#  endif
-#endif
-
-// Enable minimal optimizations for more compact code in debug mode.
-FMT_GCC_PRAGMA("GCC push_options")
-#if !defined(__OPTIMIZE__) && !defined(__NVCOMPILER) && !defined(__LCC__) && \
-    !defined(__CUDACC__)
-FMT_GCC_PRAGMA("GCC optimize(\"Og\")")
+#if FMT_UNICODE && FMT_MSC_VER
+#  pragma execution_character_set("utf-8")
 #endif
 
 FMT_BEGIN_NAMESPACE
 
 // Implementations of enable_if_t and other metafunctions for older systems.
-template <bool B, typename T = void>
+template <bool B, class T = void>
 using enable_if_t = typename std::enable_if<B, T>::type;
-template <bool B, typename T, typename F>
+template <bool B, class T, class F>
 using conditional_t = typename std::conditional<B, T, F>::type;
 template <bool B> using bool_constant = std::integral_constant<bool, B>;
 template <typename T>
@@ -267,82 +266,33 @@ template <typename T>
 using remove_const_t = typename std::remove_const<T>::type;
 template <typename T>
 using remove_cvref_t = typename std::remove_cv<remove_reference_t<T>>::type;
-template <typename T> struct type_identity {
-  using type = T;
-};
+template <typename T> struct type_identity { using type = T; };
 template <typename T> using type_identity_t = typename type_identity<T>::type;
-template <typename T>
-using underlying_t = typename std::underlying_type<T>::type;
-
-// Checks whether T is a container with contiguous storage.
-template <typename T> struct is_contiguous : std::false_type {};
-template <typename Char>
-struct is_contiguous<std::basic_string<Char>> : std::true_type {};
 
-struct monostate {
-  constexpr monostate() {}
-};
+struct monostate {};
 
 // An enable_if helper to be used in template parameters which results in much
 // shorter symbols: https://godbolt.org/z/sWw4vP. Extra parentheses are needed
 // to workaround a bug in MSVC 2019 (see #1140 and #1186).
-#ifdef FMT_DOC
-#  define FMT_ENABLE_IF(...)
-#else
-#  define FMT_ENABLE_IF(...) fmt::enable_if_t<(__VA_ARGS__), int> = 0
-#endif
-
-// This is defined in core.h instead of format.h to avoid injecting in std.
-// It is a template to avoid undesirable implicit conversions to std::byte.
-#ifdef __cpp_lib_byte
-template <typename T, FMT_ENABLE_IF(std::is_same<T, std::byte>::value)>
-inline auto format_as(T b) -> unsigned char {
-  return static_cast<unsigned char>(b);
-}
-#endif
+#define FMT_ENABLE_IF(...) enable_if_t<(__VA_ARGS__), int> = 0
 
 namespace detail {
-// Suppresses "unused variable" warnings with the method described in
-// https://herbsutter.com/2009/10/18/mailbag-shutting-up-compiler-warnings/.
-// (void)var does not work on many Intel compilers.
-template <typename... T> FMT_CONSTEXPR void ignore_unused(const T&...) {}
-
-constexpr FMT_INLINE auto is_constant_evaluated(
-    bool default_value = false) noexcept -> bool {
-// Workaround for incompatibility between libstdc++ consteval-based
-// std::is_constant_evaluated() implementation and clang-14.
-// https://github.com/fmtlib/fmt/issues/3247
-#if FMT_CPLUSPLUS >= 202002L && defined(_GLIBCXX_RELEASE) && \
-    _GLIBCXX_RELEASE >= 12 &&                                \
-    (FMT_CLANG_VERSION >= 1400 && FMT_CLANG_VERSION < 1500)
-  ignore_unused(default_value);
-  return __builtin_is_constant_evaluated();
-#elif defined(__cpp_lib_is_constant_evaluated)
-  ignore_unused(default_value);
-  return std::is_constant_evaluated();
-#else
-  return default_value;
-#endif
-}
 
-// Suppresses "conditional expression is constant" warnings.
-template <typename T> constexpr FMT_INLINE auto const_check(T value) -> T {
-  return value;
-}
+// A helper function to suppress "conditional expression is constant" warnings.
+template <typename T> constexpr T const_check(T value) { return value; }
 
 FMT_NORETURN FMT_API void assert_fail(const char* file, int line,
                                       const char* message);
 
 #ifndef FMT_ASSERT
 #  ifdef NDEBUG
-// FMT_ASSERT is not empty to avoid -Wempty-body.
-#    define FMT_ASSERT(condition, message) \
-      fmt::detail::ignore_unused((condition), (message))
+// FMT_ASSERT is not empty to avoid -Werror=empty-body.
+#    define FMT_ASSERT(condition, message) ((void)0)
 #  else
 #    define FMT_ASSERT(condition, message)                                    \
       ((condition) /* void() fails with -Winvalid-constexpr on clang 4.0.1 */ \
            ? (void)0                                                          \
-           : fmt::detail::assert_fail(__FILE__, __LINE__, (message)))
+           : ::fmt::detail::assert_fail(__FILE__, __LINE__, (message)))
 #  endif
 #endif
 
@@ -357,42 +307,44 @@ template <typename T> struct std_string_view {};
 
 #ifdef FMT_USE_INT128
 // Do nothing.
-#elif defined(__SIZEOF_INT128__) && !defined(__NVCC__) && \
-    !(FMT_CLANG_VERSION && FMT_MSC_VERSION)
+#elif defined(__SIZEOF_INT128__) && !FMT_NVCC && \
+    !(FMT_CLANG_VERSION && FMT_MSC_VER)
 #  define FMT_USE_INT128 1
-using int128_opt = __int128_t;  // An optional native 128-bit integer.
-using uint128_opt = __uint128_t;
-template <typename T> inline auto convert_for_visit(T value) -> T {
-  return value;
-}
+using int128_t = __int128_t;
+using uint128_t = __uint128_t;
 #else
 #  define FMT_USE_INT128 0
 #endif
 #if !FMT_USE_INT128
-enum class int128_opt {};
-enum class uint128_opt {};
-// Reduce template instantiations.
-template <typename T> auto convert_for_visit(T) -> monostate { return {}; }
+struct int128_t {};
+struct uint128_t {};
 #endif
 
 // Casts a nonnegative integer to unsigned.
 template <typename Int>
-FMT_CONSTEXPR auto to_unsigned(Int value) ->
-    typename std::make_unsigned<Int>::type {
-  FMT_ASSERT(std::is_unsigned<Int>::value || value >= 0, "negative value");
+FMT_CONSTEXPR typename std::make_unsigned<Int>::type to_unsigned(Int value) {
+  FMT_ASSERT(value >= 0, "negative value");
   return static_cast<typename std::make_unsigned<Int>::type>(value);
 }
 
-FMT_CONSTEXPR inline auto is_utf8() -> bool {
-  FMT_MSC_WARNING(suppress : 4566) constexpr unsigned char section[] = "\u00A7";
+FMT_SUPPRESS_MSC_WARNING(4566) constexpr unsigned char micro[] = "\u00B5";
 
-  // Avoid buggy sign extensions in MSVC's constant evaluation mode (#2297).
-  using uchar = unsigned char;
-  return FMT_UNICODE || (sizeof(section) == 3 && uchar(section[0]) == 0xC2 &&
-                         uchar(section[1]) == 0xA7);
+template <typename Char> constexpr bool is_unicode() {
+  return FMT_UNICODE || sizeof(Char) != 1 ||
+         (sizeof(micro) == 3 && micro[0] == 0xC2 && micro[1] == 0xB5);
 }
+
+#ifdef __cpp_char8_t
+using char8_type = char8_t;
+#else
+enum char8_type : unsigned char {};
+#endif
 }  // namespace detail
 
+#ifdef FMT_USE_INTERNAL
+namespace internal = detail;  // DEPRECATED
+#endif
+
 /**
   An implementation of ``std::basic_string_view`` for pre-C++17. It provides a
   subset of the API. ``fmt::basic_string_view`` is used for format strings even
@@ -400,7 +352,6 @@ FMT_CONSTEXPR inline auto is_utf8() -> bool {
   compiled with a different ``-std`` option than the client code (which is not
   recommended).
  */
-FMT_EXPORT
 template <typename Char> class basic_string_view {
  private:
   const Char* data_;
@@ -410,11 +361,12 @@ template <typename Char> class basic_string_view {
   using value_type = Char;
   using iterator = const Char*;
 
-  constexpr basic_string_view() noexcept : data_(nullptr), size_(0) {}
+  constexpr basic_string_view() FMT_NOEXCEPT : data_(nullptr), size_(0) {}
 
   /** Constructs a string reference object from a C string and a size. */
-  constexpr basic_string_view(const Char* s, size_t count) noexcept
-      : data_(s), size_(count) {}
+  constexpr basic_string_view(const Char* s, size_t count) FMT_NOEXCEPT
+      : data_(s),
+        size_(count) {}
 
   /**
     \rst
@@ -422,58 +374,42 @@ template <typename Char> class basic_string_view {
     the size with ``std::char_traits<Char>::length``.
     \endrst
    */
-  FMT_CONSTEXPR_CHAR_TRAITS
-  FMT_INLINE
+#if __cplusplus >= 201703L  // C++17's char_traits::length() is constexpr.
+  FMT_CONSTEXPR
+#endif
   basic_string_view(const Char* s)
-      : data_(s),
-        size_(detail::const_check(std::is_same<Char, char>::value &&
-                                  !detail::is_constant_evaluated(true))
-                  ? std::strlen(reinterpret_cast<const char*>(s))
-                  : std::char_traits<Char>::length(s)) {}
+      : data_(s), size_(std::char_traits<Char>::length(s)) {}
 
   /** Constructs a string reference from a ``std::basic_string`` object. */
   template <typename Traits, typename Alloc>
   FMT_CONSTEXPR basic_string_view(
-      const std::basic_string<Char, Traits, Alloc>& s) noexcept
-      : data_(s.data()), size_(s.size()) {}
+      const std::basic_string<Char, Traits, Alloc>& s) FMT_NOEXCEPT
+      : data_(s.data()),
+        size_(s.size()) {}
 
   template <typename S, FMT_ENABLE_IF(std::is_same<
                                       S, detail::std_string_view<Char>>::value)>
-  FMT_CONSTEXPR basic_string_view(S s) noexcept
-      : data_(s.data()), size_(s.size()) {}
+  FMT_CONSTEXPR basic_string_view(S s) FMT_NOEXCEPT : data_(s.data()),
+                                                      size_(s.size()) {}
 
   /** Returns a pointer to the string data. */
-  constexpr auto data() const noexcept -> const Char* { return data_; }
+  constexpr const Char* data() const { return data_; }
 
   /** Returns the string size. */
-  constexpr auto size() const noexcept -> size_t { return size_; }
+  constexpr size_t size() const { return size_; }
 
-  constexpr auto begin() const noexcept -> iterator { return data_; }
-  constexpr auto end() const noexcept -> iterator { return data_ + size_; }
+  constexpr iterator begin() const { return data_; }
+  constexpr iterator end() const { return data_ + size_; }
 
-  constexpr auto operator[](size_t pos) const noexcept -> const Char& {
-    return data_[pos];
-  }
+  constexpr const Char& operator[](size_t pos) const { return data_[pos]; }
 
-  FMT_CONSTEXPR void remove_prefix(size_t n) noexcept {
+  FMT_CONSTEXPR void remove_prefix(size_t n) {
     data_ += n;
     size_ -= n;
   }
 
-  FMT_CONSTEXPR_CHAR_TRAITS bool starts_with(
-      basic_string_view<Char> sv) const noexcept {
-    return size_ >= sv.size_ &&
-           std::char_traits<Char>::compare(data_, sv.data_, sv.size_) == 0;
-  }
-  FMT_CONSTEXPR_CHAR_TRAITS bool starts_with(Char c) const noexcept {
-    return size_ >= 1 && std::char_traits<Char>::eq(*data_, c);
-  }
-  FMT_CONSTEXPR_CHAR_TRAITS bool starts_with(const Char* s) const {
-    return starts_with(basic_string_view<Char>(s));
-  }
-
   // Lexicographically compare this string reference to other.
-  FMT_CONSTEXPR_CHAR_TRAITS auto compare(basic_string_view other) const -> int {
+  int compare(basic_string_view other) const {
     size_t str_size = size_ < other.size_ ? size_ : other.size_;
     int result = std::char_traits<Char>::compare(data_, other.data_, str_size);
     if (result == 0)
@@ -481,77 +417,97 @@ template <typename Char> class basic_string_view {
     return result;
   }
 
-  FMT_CONSTEXPR_CHAR_TRAITS friend auto operator==(basic_string_view lhs,
-                                                   basic_string_view rhs)
-      -> bool {
+  friend bool operator==(basic_string_view lhs, basic_string_view rhs) {
     return lhs.compare(rhs) == 0;
   }
-  friend auto operator!=(basic_string_view lhs, basic_string_view rhs) -> bool {
+  friend bool operator!=(basic_string_view lhs, basic_string_view rhs) {
     return lhs.compare(rhs) != 0;
   }
-  friend auto operator<(basic_string_view lhs, basic_string_view rhs) -> bool {
+  friend bool operator<(basic_string_view lhs, basic_string_view rhs) {
     return lhs.compare(rhs) < 0;
   }
-  friend auto operator<=(basic_string_view lhs, basic_string_view rhs) -> bool {
+  friend bool operator<=(basic_string_view lhs, basic_string_view rhs) {
     return lhs.compare(rhs) <= 0;
   }
-  friend auto operator>(basic_string_view lhs, basic_string_view rhs) -> bool {
+  friend bool operator>(basic_string_view lhs, basic_string_view rhs) {
     return lhs.compare(rhs) > 0;
   }
-  friend auto operator>=(basic_string_view lhs, basic_string_view rhs) -> bool {
+  friend bool operator>=(basic_string_view lhs, basic_string_view rhs) {
     return lhs.compare(rhs) >= 0;
   }
 };
 
-FMT_EXPORT
 using string_view = basic_string_view<char>;
+using wstring_view = basic_string_view<wchar_t>;
 
 /** Specifies if ``T`` is a character type. Can be specialized by users. */
-FMT_EXPORT
 template <typename T> struct is_char : std::false_type {};
 template <> struct is_char<char> : std::true_type {};
+template <> struct is_char<wchar_t> : std::true_type {};
+template <> struct is_char<detail::char8_type> : std::true_type {};
+template <> struct is_char<char16_t> : std::true_type {};
+template <> struct is_char<char32_t> : std::true_type {};
 
-namespace detail {
-
-// A base class for compile-time strings.
-struct compile_string {};
+/**
+  \rst
+  Returns a string view of `s`. In order to add custom string type support to
+  {fmt} provide an overload of `to_string_view` for it in the same namespace as
+  the type for the argument-dependent lookup to work.
 
-template <typename S>
-struct is_compile_string : std::is_base_of<compile_string, S> {};
+  **Example**::
 
+    namespace my_ns {
+    inline string_view to_string_view(const my_string& s) {
+      return {s.data(), s.length()};
+    }
+    }
+    std::string message = fmt::format(my_string("The answer is {}"), 42);
+  \endrst
+ */
 template <typename Char, FMT_ENABLE_IF(is_char<Char>::value)>
-FMT_INLINE auto to_string_view(const Char* s) -> basic_string_view<Char> {
+inline basic_string_view<Char> to_string_view(const Char* s) {
   return s;
 }
+
 template <typename Char, typename Traits, typename Alloc>
-inline auto to_string_view(const std::basic_string<Char, Traits, Alloc>& s)
-    -> basic_string_view<Char> {
+inline basic_string_view<Char> to_string_view(
+    const std::basic_string<Char, Traits, Alloc>& s) {
   return s;
 }
+
 template <typename Char>
-constexpr auto to_string_view(basic_string_view<Char> s)
-    -> basic_string_view<Char> {
+inline basic_string_view<Char> to_string_view(basic_string_view<Char> s) {
   return s;
 }
+
 template <typename Char,
-          FMT_ENABLE_IF(!std::is_empty<std_string_view<Char>>::value)>
-inline auto to_string_view(std_string_view<Char> s) -> basic_string_view<Char> {
+          FMT_ENABLE_IF(!std::is_empty<detail::std_string_view<Char>>::value)>
+inline basic_string_view<Char> to_string_view(detail::std_string_view<Char> s) {
   return s;
 }
+
+// A base class for compile-time strings. It is defined in the fmt namespace to
+// make formatting functions visible via ADL, e.g. format(FMT_STRING("{}"), 42).
+struct compile_string {};
+
+template <typename S>
+struct is_compile_string : std::is_base_of<compile_string, S> {};
+
 template <typename S, FMT_ENABLE_IF(is_compile_string<S>::value)>
-constexpr auto to_string_view(const S& s)
-    -> basic_string_view<typename S::char_type> {
-  return basic_string_view<typename S::char_type>(s);
+constexpr basic_string_view<typename S::char_type> to_string_view(const S& s) {
+  return s;
 }
+
+namespace detail {
 void to_string_view(...);
+using fmt::to_string_view;
 
 // Specifies whether S is a string type convertible to fmt::basic_string_view.
 // It should be a constexpr function but MSVC 2017 fails to compile it in
 // enable_if and MSVC 2015 fails to compile it as an alias template.
-// ADL is intentionally disabled as to_string_view is not an extension point.
 template <typename S>
-struct is_string
-    : std::is_class<decltype(detail::to_string_view(std::declval<S>()))> {};
+struct is_string : std::is_class<decltype(to_string_view(std::declval<S>()))> {
+};
 
 template <typename S, typename = void> struct char_t_impl {};
 template <typename S> struct char_t_impl<S, enable_if_t<is_string<S>::value>> {
@@ -559,95 +515,27 @@ template <typename S> struct char_t_impl<S, enable_if_t<is_string<S>::value>> {
   using type = typename result::value_type;
 };
 
-enum class type {
-  none_type,
-  // Integer types should go first,
-  int_type,
-  uint_type,
-  long_long_type,
-  ulong_long_type,
-  int128_type,
-  uint128_type,
-  bool_type,
-  char_type,
-  last_integer_type = char_type,
-  // followed by floating-point types.
-  float_type,
-  double_type,
-  long_double_type,
-  last_numeric_type = long_double_type,
-  cstring_type,
-  string_type,
-  pointer_type,
-  custom_type
-};
-
-// Maps core type T to the corresponding type enum constant.
-template <typename T, typename Char>
-struct type_constant : std::integral_constant<type, type::custom_type> {};
-
-#define FMT_TYPE_CONSTANT(Type, constant) \
-  template <typename Char>                \
-  struct type_constant<Type, Char>        \
-      : std::integral_constant<type, type::constant> {}
-
-FMT_TYPE_CONSTANT(int, int_type);
-FMT_TYPE_CONSTANT(unsigned, uint_type);
-FMT_TYPE_CONSTANT(long long, long_long_type);
-FMT_TYPE_CONSTANT(unsigned long long, ulong_long_type);
-FMT_TYPE_CONSTANT(int128_opt, int128_type);
-FMT_TYPE_CONSTANT(uint128_opt, uint128_type);
-FMT_TYPE_CONSTANT(bool, bool_type);
-FMT_TYPE_CONSTANT(Char, char_type);
-FMT_TYPE_CONSTANT(float, float_type);
-FMT_TYPE_CONSTANT(double, double_type);
-FMT_TYPE_CONSTANT(long double, long_double_type);
-FMT_TYPE_CONSTANT(const Char*, cstring_type);
-FMT_TYPE_CONSTANT(basic_string_view<Char>, string_type);
-FMT_TYPE_CONSTANT(const void*, pointer_type);
-
-constexpr bool is_integral_type(type t) {
-  return t > type::none_type && t <= type::last_integer_type;
-}
-constexpr bool is_arithmetic_type(type t) {
-  return t > type::none_type && t <= type::last_numeric_type;
-}
-
-constexpr auto set(type rhs) -> int { return 1 << static_cast<int>(rhs); }
-constexpr auto in(type t, int set) -> bool {
-  return ((set >> static_cast<int>(t)) & 1) != 0;
+// Reports a compile-time error if S is not a valid format string.
+template <typename..., typename S, FMT_ENABLE_IF(!is_compile_string<S>::value)>
+FMT_INLINE void check_format_string(const S&) {
+#ifdef FMT_ENFORCE_COMPILE_STRING
+  static_assert(is_compile_string<S>::value,
+                "FMT_ENFORCE_COMPILE_STRING requires all format strings to use "
+                "FMT_STRING.");
+#endif
 }
-
-// Bitsets of types.
-enum {
-  sint_set =
-      set(type::int_type) | set(type::long_long_type) | set(type::int128_type),
-  uint_set = set(type::uint_type) | set(type::ulong_long_type) |
-             set(type::uint128_type),
-  bool_set = set(type::bool_type),
-  char_set = set(type::char_type),
-  float_set = set(type::float_type) | set(type::double_type) |
-              set(type::long_double_type),
-  string_set = set(type::string_type),
-  cstring_set = set(type::cstring_type),
-  pointer_set = set(type::pointer_type)
-};
-
-FMT_NORETURN FMT_API void throw_format_error(const char* message);
+template <typename..., typename S, FMT_ENABLE_IF(is_compile_string<S>::value)>
+void check_format_string(S);
 
 struct error_handler {
   constexpr error_handler() = default;
+  constexpr error_handler(const error_handler&) = default;
 
   // This function is intentionally not constexpr to give a compile-time error.
-  FMT_NORETURN void on_error(const char* message) {
-    throw_format_error(message);
-  }
+  FMT_NORETURN FMT_API void on_error(const char* message);
 };
 }  // namespace detail
 
-/** Throws ``format_error`` with a given message. */
-using detail::throw_format_error;
-
 /** String's character type. */
 template <typename S> using char_t = typename detail::char_t_impl<S>::type;
 
@@ -655,37 +543,43 @@ template <typename S> using char_t = typename detail::char_t_impl<S>::type;
   \rst
   Parsing context consisting of a format string range being parsed and an
   argument counter for automatic indexing.
-  You can use the ``format_parse_context`` type alias for ``char`` instead.
+
+  You can use one of the following type aliases for common character types:
+
+  +-----------------------+-------------------------------------+
+  | Type                  | Definition                          |
+  +=======================+=====================================+
+  | format_parse_context  | basic_format_parse_context<char>    |
+  +-----------------------+-------------------------------------+
+  | wformat_parse_context | basic_format_parse_context<wchar_t> |
+  +-----------------------+-------------------------------------+
   \endrst
  */
-FMT_EXPORT
-template <typename Char> class basic_format_parse_context {
+template <typename Char, typename ErrorHandler = detail::error_handler>
+class basic_format_parse_context : private ErrorHandler {
  private:
   basic_string_view<Char> format_str_;
   int next_arg_id_;
 
-  FMT_CONSTEXPR void do_check_arg_id(int id);
-
  public:
   using char_type = Char;
-  using iterator = const Char*;
+  using iterator = typename basic_string_view<Char>::iterator;
 
   explicit constexpr basic_format_parse_context(
-      basic_string_view<Char> format_str, int next_arg_id = 0)
-      : format_str_(format_str), next_arg_id_(next_arg_id) {}
+      basic_string_view<Char> format_str, ErrorHandler eh = {},
+      int next_arg_id = 0)
+      : ErrorHandler(eh), format_str_(format_str), next_arg_id_(next_arg_id) {}
 
   /**
     Returns an iterator to the beginning of the format string range being
     parsed.
    */
-  constexpr auto begin() const noexcept -> iterator {
-    return format_str_.begin();
-  }
+  constexpr iterator begin() const FMT_NOEXCEPT { return format_str_.begin(); }
 
   /**
     Returns an iterator past the end of the format string range being parsed.
    */
-  constexpr auto end() const noexcept -> iterator { return format_str_.end(); }
+  constexpr iterator end() const FMT_NOEXCEPT { return format_str_.end(); }
 
   /** Advances the begin iterator to ``it``. */
   FMT_CONSTEXPR void advance_to(iterator it) {
@@ -696,105 +590,72 @@ template <typename Char> class basic_format_parse_context {
     Reports an error if using the manual argument indexing; otherwise returns
     the next argument index and switches to the automatic indexing.
    */
-  FMT_CONSTEXPR auto next_arg_id() -> int {
-    if (next_arg_id_ < 0) {
-      detail::throw_format_error(
-          "cannot switch from manual to automatic argument indexing");
-      return 0;
-    }
-    int id = next_arg_id_++;
-    do_check_arg_id(id);
-    return id;
+  FMT_CONSTEXPR int next_arg_id() {
+    // Don't check if the argument id is valid to avoid overhead and because it
+    // will be checked during formatting anyway.
+    if (next_arg_id_ >= 0) return next_arg_id_++;
+    on_error("cannot switch from manual to automatic argument indexing");
+    return 0;
   }
 
   /**
     Reports an error if using the automatic argument indexing; otherwise
     switches to the manual indexing.
    */
-  FMT_CONSTEXPR void check_arg_id(int id) {
-    if (next_arg_id_ > 0) {
-      detail::throw_format_error(
-          "cannot switch from automatic to manual argument indexing");
-      return;
-    }
-    next_arg_id_ = -1;
-    do_check_arg_id(id);
+  FMT_CONSTEXPR void check_arg_id(int) {
+    if (next_arg_id_ > 0)
+      on_error("cannot switch from automatic to manual argument indexing");
+    else
+      next_arg_id_ = -1;
   }
+
   FMT_CONSTEXPR void check_arg_id(basic_string_view<Char>) {}
-  FMT_CONSTEXPR void check_dynamic_spec(int arg_id);
+
+  FMT_CONSTEXPR void on_error(const char* message) {
+    ErrorHandler::on_error(message);
+  }
+
+  constexpr ErrorHandler error_handler() const { return *this; }
 };
 
-FMT_EXPORT
 using format_parse_context = basic_format_parse_context<char>;
+using wformat_parse_context = basic_format_parse_context<wchar_t>;
 
-namespace detail {
-// A parse context with extra data used only in compile-time checks.
-template <typename Char>
-class compile_parse_context : public basic_format_parse_context<Char> {
- private:
-  int num_args_;
-  const type* types_;
-  using base = basic_format_parse_context<Char>;
-
- public:
-  explicit FMT_CONSTEXPR compile_parse_context(
-      basic_string_view<Char> format_str, int num_args, const type* types,
-      int next_arg_id = 0)
-      : base(format_str, next_arg_id), num_args_(num_args), types_(types) {}
+template <typename Context> class basic_format_arg;
+template <typename Context> class basic_format_args;
+template <typename Context> class dynamic_format_arg_store;
 
-  constexpr auto num_args() const -> int { return num_args_; }
-  constexpr auto arg_type(int id) const -> type { return types_[id]; }
+// A formatter for objects of type T.
+template <typename T, typename Char = char, typename Enable = void>
+struct formatter {
+  // A deleted default constructor indicates a disabled formatter.
+  formatter() = delete;
+};
 
-  FMT_CONSTEXPR auto next_arg_id() -> int {
-    int id = base::next_arg_id();
-    if (id >= num_args_) throw_format_error("argument not found");
-    return id;
-  }
+// Specifies if T has an enabled formatter specialization. A type can be
+// formattable even if it doesn't have a formatter e.g. via a conversion.
+template <typename T, typename Context>
+using has_formatter =
+    std::is_constructible<typename Context::template formatter_type<T>>;
 
-  FMT_CONSTEXPR void check_arg_id(int id) {
-    base::check_arg_id(id);
-    if (id >= num_args_) throw_format_error("argument not found");
-  }
-  using base::check_arg_id;
+// Checks whether T is a container with contiguous storage.
+template <typename T> struct is_contiguous : std::false_type {};
+template <typename Char>
+struct is_contiguous<std::basic_string<Char>> : std::true_type {};
 
-  FMT_CONSTEXPR void check_dynamic_spec(int arg_id) {
-    detail::ignore_unused(arg_id);
-#if !defined(__LCC__)
-    if (arg_id < num_args_ && types_ && !is_integral_type(types_[arg_id]))
-      throw_format_error("width/precision is not integer");
-#endif
-  }
-};
+namespace detail {
 
 // Extracts a reference to the container from back_insert_iterator.
 template <typename Container>
-inline auto get_container(std::back_insert_iterator<Container> it)
-    -> Container& {
-  using base = std::back_insert_iterator<Container>;
-  struct accessor : base {
-    accessor(base b) : base(b) {}
-    using base::container;
+inline Container& get_container(std::back_insert_iterator<Container> it) {
+  using bi_iterator = std::back_insert_iterator<Container>;
+  struct accessor : bi_iterator {
+    accessor(bi_iterator iter) : bi_iterator(iter) {}
+    using bi_iterator::container;
   };
   return *accessor(it).container;
 }
 
-template <typename Char, typename InputIt, typename OutputIt>
-FMT_CONSTEXPR auto copy_str(InputIt begin, InputIt end, OutputIt out)
-    -> OutputIt {
-  while (begin != end) *out++ = static_cast<Char>(*begin++);
-  return out;
-}
-
-template <typename Char, typename T, typename U,
-          FMT_ENABLE_IF(
-              std::is_same<remove_const_t<T>, U>::value&& is_char<U>::value)>
-FMT_CONSTEXPR auto copy_str(T* begin, T* end, U* out) -> U* {
-  if (is_constant_evaluated()) return copy_str<Char, T*, U*>(begin, end, out);
-  auto size = to_unsigned(end - begin);
-  if (size > 0) memcpy(out, begin, size * sizeof(U));
-  return out + size;
-}
-
 /**
   \rst
   A contiguous memory buffer with an optional growing ability. It is an internal
@@ -809,23 +670,24 @@ template <typename T> class buffer {
 
  protected:
   // Don't initialize ptr_ since it is not accessed to save a few cycles.
-  FMT_MSC_WARNING(suppress : 26495)
-  buffer(size_t sz) noexcept : size_(sz), capacity_(sz) {}
+  FMT_SUPPRESS_MSC_WARNING(26495)
+  buffer(size_t sz) FMT_NOEXCEPT : size_(sz), capacity_(sz) {}
 
-  FMT_CONSTEXPR20 buffer(T* p = nullptr, size_t sz = 0, size_t cap = 0) noexcept
-      : ptr_(p), size_(sz), capacity_(cap) {}
+  buffer(T* p = nullptr, size_t sz = 0, size_t cap = 0) FMT_NOEXCEPT
+      : ptr_(p),
+        size_(sz),
+        capacity_(cap) {}
 
-  FMT_CONSTEXPR20 ~buffer() = default;
-  buffer(buffer&&) = default;
+  ~buffer() = default;
 
   /** Sets the buffer data and capacity. */
-  FMT_CONSTEXPR void set(T* buf_data, size_t buf_capacity) noexcept {
+  void set(T* buf_data, size_t buf_capacity) FMT_NOEXCEPT {
     ptr_ = buf_data;
     capacity_ = buf_capacity;
   }
 
   /** Increases the buffer capacity to hold at least *capacity* elements. */
-  virtual FMT_CONSTEXPR20 void grow(size_t capacity) = 0;
+  virtual void grow(size_t capacity) = 0;
 
  public:
   using value_type = T;
@@ -834,28 +696,30 @@ template <typename T> class buffer {
   buffer(const buffer&) = delete;
   void operator=(const buffer&) = delete;
 
-  FMT_INLINE auto begin() noexcept -> T* { return ptr_; }
-  FMT_INLINE auto end() noexcept -> T* { return ptr_ + size_; }
+  T* begin() FMT_NOEXCEPT { return ptr_; }
+  T* end() FMT_NOEXCEPT { return ptr_ + size_; }
 
-  FMT_INLINE auto begin() const noexcept -> const T* { return ptr_; }
-  FMT_INLINE auto end() const noexcept -> const T* { return ptr_ + size_; }
+  const T* begin() const FMT_NOEXCEPT { return ptr_; }
+  const T* end() const FMT_NOEXCEPT { return ptr_ + size_; }
 
   /** Returns the size of this buffer. */
-  constexpr auto size() const noexcept -> size_t { return size_; }
+  size_t size() const FMT_NOEXCEPT { return size_; }
 
   /** Returns the capacity of this buffer. */
-  constexpr auto capacity() const noexcept -> size_t { return capacity_; }
+  size_t capacity() const FMT_NOEXCEPT { return capacity_; }
 
-  /** Returns a pointer to the buffer data (not null-terminated). */
-  FMT_CONSTEXPR auto data() noexcept -> T* { return ptr_; }
-  FMT_CONSTEXPR auto data() const noexcept -> const T* { return ptr_; }
+  /** Returns a pointer to the buffer data. */
+  T* data() FMT_NOEXCEPT { return ptr_; }
+
+  /** Returns a pointer to the buffer data. */
+  const T* data() const FMT_NOEXCEPT { return ptr_; }
 
   /** Clears this buffer. */
   void clear() { size_ = 0; }
 
   // Tries resizing the buffer to contain *count* elements. If T is a POD type
   // the new elements may not be initialized.
-  FMT_CONSTEXPR20 void try_resize(size_t count) {
+  void try_resize(size_t count) {
     try_reserve(count);
     size_ = count <= capacity_ ? count : capacity_;
   }
@@ -864,11 +728,11 @@ template <typename T> class buffer {
   // capacity by a smaller amount than requested but guarantees there is space
   // for at least one additional element either by increasing the capacity or by
   // flushing the buffer if it is full.
-  FMT_CONSTEXPR20 void try_reserve(size_t new_capacity) {
+  void try_reserve(size_t new_capacity) {
     if (new_capacity > capacity_) grow(new_capacity);
   }
 
-  FMT_CONSTEXPR20 void push_back(const T& value) {
+  void push_back(const T& value) {
     try_reserve(size_ + 1);
     ptr_[size_++] = value;
   }
@@ -876,19 +740,16 @@ template <typename T> class buffer {
   /** Appends data to the end of the buffer. */
   template <typename U> void append(const U* begin, const U* end);
 
-  template <typename Idx> FMT_CONSTEXPR auto operator[](Idx index) -> T& {
-    return ptr_[index];
-  }
-  template <typename Idx>
-  FMT_CONSTEXPR auto operator[](Idx index) const -> const T& {
+  template <typename I> T& operator[](I index) { return ptr_[index]; }
+  template <typename I> const T& operator[](I index) const {
     return ptr_[index];
   }
 };
 
 struct buffer_traits {
   explicit buffer_traits(size_t) {}
-  auto count() const -> size_t { return 0; }
-  auto limit(size_t size) -> size_t { return size; }
+  size_t count() const { return 0; }
+  size_t limit(size_t size) { return size; }
 };
 
 class fixed_buffer_traits {
@@ -898,8 +759,8 @@ class fixed_buffer_traits {
 
  public:
   explicit fixed_buffer_traits(size_t limit) : limit_(limit) {}
-  auto count() const -> size_t { return count_; }
-  auto limit(size_t size) -> size_t {
+  size_t count() const { return count_; }
+  size_t limit(size_t size) {
     size_t n = limit_ > count_ ? limit_ - count_ : 0;
     count_ += size;
     return size < n ? size : n;
@@ -915,84 +776,33 @@ class iterator_buffer final : public Traits, public buffer<T> {
   T data_[buffer_size];
 
  protected:
-  FMT_CONSTEXPR20 void grow(size_t) override {
+  void grow(size_t) final FMT_OVERRIDE {
     if (this->size() == buffer_size) flush();
   }
-
-  void flush() {
-    auto size = this->size();
-    this->clear();
-    out_ = copy_str<T>(data_, data_ + this->limit(size), out_);
-  }
+  void flush();
 
  public:
   explicit iterator_buffer(OutputIt out, size_t n = buffer_size)
-      : Traits(n), buffer<T>(data_, 0, buffer_size), out_(out) {}
-  iterator_buffer(iterator_buffer&& other)
-      : Traits(other), buffer<T>(data_, 0, buffer_size), out_(other.out_) {}
-  ~iterator_buffer() { flush(); }
-
-  auto out() -> OutputIt {
-    flush();
-    return out_;
-  }
-  auto count() const -> size_t { return Traits::count() + this->size(); }
-};
-
-template <typename T>
-class iterator_buffer<T*, T, fixed_buffer_traits> final
-    : public fixed_buffer_traits,
-      public buffer<T> {
- private:
-  T* out_;
-  enum { buffer_size = 256 };
-  T data_[buffer_size];
-
- protected:
-  FMT_CONSTEXPR20 void grow(size_t) override {
-    if (this->size() == this->capacity()) flush();
-  }
-
-  void flush() {
-    size_t n = this->limit(this->size());
-    if (this->data() == out_) {
-      out_ += n;
-      this->set(data_, buffer_size);
-    }
-    this->clear();
-  }
-
- public:
-  explicit iterator_buffer(T* out, size_t n = buffer_size)
-      : fixed_buffer_traits(n), buffer<T>(out, 0, n), out_(out) {}
-  iterator_buffer(iterator_buffer&& other)
-      : fixed_buffer_traits(other),
-        buffer<T>(std::move(other)),
-        out_(other.out_) {
-    if (this->data() != out_) {
-      this->set(data_, buffer_size);
-      this->clear();
-    }
-  }
+      : Traits(n),
+        buffer<T>(data_, 0, buffer_size),
+        out_(out) {}
   ~iterator_buffer() { flush(); }
 
-  auto out() -> T* {
+  OutputIt out() {
     flush();
     return out_;
   }
-  auto count() const -> size_t {
-    return fixed_buffer_traits::count() + this->size();
-  }
+  size_t count() const { return Traits::count() + this->size(); }
 };
 
 template <typename T> class iterator_buffer<T*, T> final : public buffer<T> {
  protected:
-  FMT_CONSTEXPR20 void grow(size_t) override {}
+  void grow(size_t) final FMT_OVERRIDE {}
 
  public:
   explicit iterator_buffer(T* out, size_t = 0) : buffer<T>(out, 0, ~size_t()) {}
 
-  auto out() -> T* { return &*this->end(); }
+  T* out() { return &*this->end(); }
 };
 
 // A buffer that writes to a container with the contiguous storage.
@@ -1005,7 +815,7 @@ class iterator_buffer<std::back_insert_iterator<Container>,
   Container& container_;
 
  protected:
-  FMT_CONSTEXPR20 void grow(size_t capacity) override {
+  void grow(size_t capacity) final FMT_OVERRIDE {
     container_.resize(capacity);
     this->set(&container_[0], capacity);
   }
@@ -1015,8 +825,7 @@ class iterator_buffer<std::back_insert_iterator<Container>,
       : buffer<typename Container::value_type>(c.size()), container_(c) {}
   explicit iterator_buffer(std::back_insert_iterator<Container> out, size_t = 0)
       : iterator_buffer(get_container(out)) {}
-
-  auto out() -> std::back_insert_iterator<Container> {
+  std::back_insert_iterator<Container> out() {
     return std::back_inserter(container_);
   }
 };
@@ -1029,7 +838,7 @@ template <typename T = char> class counting_buffer final : public buffer<T> {
   size_t count_ = 0;
 
  protected:
-  FMT_CONSTEXPR20 void grow(size_t) override {
+  void grow(size_t) final FMT_OVERRIDE {
     if (this->size() != buffer_size) return;
     count_ += this->size();
     this->clear();
@@ -1038,106 +847,61 @@ template <typename T = char> class counting_buffer final : public buffer<T> {
  public:
   counting_buffer() : buffer<T>(data_, 0, buffer_size) {}
 
-  auto count() -> size_t { return count_ + this->size(); }
+  size_t count() { return count_ + this->size(); }
 };
-}  // namespace detail
-
-template <typename Char>
-FMT_CONSTEXPR void basic_format_parse_context<Char>::do_check_arg_id(int id) {
-  // Argument id is only checked at compile-time during parsing because
-  // formatting has its own validation.
-  if (detail::is_constant_evaluated() &&
-      (!FMT_GCC_VERSION || FMT_GCC_VERSION >= 1200)) {
-    using context = detail::compile_parse_context<Char>;
-    if (id >= static_cast<context*>(this)->num_args())
-      detail::throw_format_error("argument not found");
-  }
-}
-
-template <typename Char>
-FMT_CONSTEXPR void basic_format_parse_context<Char>::check_dynamic_spec(
-    int arg_id) {
-  if (detail::is_constant_evaluated() &&
-      (!FMT_GCC_VERSION || FMT_GCC_VERSION >= 1200)) {
-    using context = detail::compile_parse_context<Char>;
-    static_cast<context*>(this)->check_dynamic_spec(arg_id);
-  }
-}
-
-FMT_EXPORT template <typename Context> class basic_format_arg;
-FMT_EXPORT template <typename Context> class basic_format_args;
-FMT_EXPORT template <typename Context> class dynamic_format_arg_store;
-
-// A formatter for objects of type T.
-FMT_EXPORT
-template <typename T, typename Char = char, typename Enable = void>
-struct formatter {
-  // A deleted default constructor indicates a disabled formatter.
-  formatter() = delete;
-};
-
-// Specifies if T has an enabled formatter specialization. A type can be
-// formattable even if it doesn't have a formatter e.g. via a conversion.
-template <typename T, typename Context>
-using has_formatter =
-    std::is_constructible<typename Context::template formatter_type<T>>;
 
-// An output iterator that appends to a buffer.
+// An output iterator that appends to the buffer.
 // It is used to reduce symbol sizes for the common case.
-class appender : public std::back_insert_iterator<detail::buffer<char>> {
-  using base = std::back_insert_iterator<detail::buffer<char>>;
+template <typename T>
+class buffer_appender : public std::back_insert_iterator<buffer<T>> {
+  using base = std::back_insert_iterator<buffer<T>>;
 
  public:
-  using std::back_insert_iterator<detail::buffer<char>>::back_insert_iterator;
-  appender(base it) noexcept : base(it) {}
-  FMT_UNCHECKED_ITERATOR(appender);
+  explicit buffer_appender(buffer<T>& buf) : base(buf) {}
+  buffer_appender(base it) : base(it) {}
 
-  auto operator++() noexcept -> appender& { return *this; }
-  auto operator++(int) noexcept -> appender { return *this; }
-};
-
-namespace detail {
-
-template <typename Context, typename T>
-constexpr auto has_const_formatter_impl(T*)
-    -> decltype(typename Context::template formatter_type<T>().format(
-                    std::declval<const T&>(), std::declval<Context&>()),
-                true) {
-  return true;
-}
-template <typename Context>
-constexpr auto has_const_formatter_impl(...) -> bool {
-  return false;
-}
-template <typename T, typename Context>
-constexpr auto has_const_formatter() -> bool {
-  return has_const_formatter_impl<Context>(static_cast<T*>(nullptr));
-}
+  buffer_appender& operator++() {
+    base::operator++();
+    return *this;
+  }
 
-template <typename T>
-using buffer_appender = conditional_t<std::is_same<T, char>::value, appender,
-                                      std::back_insert_iterator<buffer<T>>>;
+  buffer_appender operator++(int) {
+    buffer_appender tmp = *this;
+    ++*this;
+    return tmp;
+  }
+};
 
-// Maps an output iterator to a buffer.
+// Maps an output iterator into a buffer.
 template <typename T, typename OutputIt>
-auto get_buffer(OutputIt out) -> iterator_buffer<OutputIt, T> {
-  return iterator_buffer<OutputIt, T>(out);
+iterator_buffer<OutputIt, T> get_buffer(OutputIt);
+template <typename T> buffer<T>& get_buffer(buffer_appender<T>);
+
+template <typename OutputIt> OutputIt get_buffer_init(OutputIt out) {
+  return out;
 }
-template <typename T, typename Buf,
-          FMT_ENABLE_IF(std::is_base_of<buffer<char>, Buf>::value)>
-auto get_buffer(std::back_insert_iterator<Buf> out) -> buffer<char>& {
+template <typename T> buffer<T>& get_buffer_init(buffer_appender<T> out) {
   return get_container(out);
 }
 
-template <typename Buf, typename OutputIt>
-FMT_INLINE auto get_iterator(Buf& buf, OutputIt) -> decltype(buf.out()) {
+template <typename Buffer>
+auto get_iterator(Buffer& buf) -> decltype(buf.out()) {
   return buf.out();
 }
-template <typename T, typename OutputIt>
-auto get_iterator(buffer<T>&, OutputIt out) -> OutputIt {
-  return out;
+template <typename T> buffer_appender<T> get_iterator(buffer<T>& buf) {
+  return buffer_appender<T>(buf);
 }
 
+template <typename T, typename Char = char, typename Enable = void>
+struct fallback_formatter {
+  fallback_formatter() = delete;
+};
+
+// Specifies if T has an enabled fallback_formatter specialization.
+template <typename T, typename Context>
+using has_fallback_formatter =
+    std::is_constructible<fallback_formatter<T, typename Context::char_type>>;
+
 struct view {};
 
 template <typename Char, typename T> struct named_arg : view {
@@ -1161,8 +925,8 @@ struct arg_data {
   template <typename... U>
   arg_data(const U&... init) : args_{T(named_args_, NUM_NAMED_ARGS), init...} {}
   arg_data(const arg_data& other) = delete;
-  auto args() const -> const T* { return args_ + 1; }
-  auto named_args() -> named_arg_info<Char>* { return named_args_; }
+  const T* args() const { return args_ + 1; }
+  named_arg_info<Char>* named_args() { return named_args_; }
 };
 
 template <typename T, typename Char, size_t NUM_ARGS>
@@ -1171,58 +935,99 @@ struct arg_data<T, Char, NUM_ARGS, 0> {
   T args_[NUM_ARGS != 0 ? NUM_ARGS : +1];
 
   template <typename... U>
-  FMT_CONSTEXPR FMT_INLINE arg_data(const U&... init) : args_{init...} {}
-  FMT_CONSTEXPR FMT_INLINE auto args() const -> const T* { return args_; }
-  FMT_CONSTEXPR FMT_INLINE auto named_args() -> std::nullptr_t {
-    return nullptr;
-  }
+  FMT_INLINE arg_data(const U&... init) : args_{init...} {}
+  FMT_INLINE const T* args() const { return args_; }
+  FMT_INLINE std::nullptr_t named_args() { return nullptr; }
 };
 
 template <typename Char>
 inline void init_named_args(named_arg_info<Char>*, int, int) {}
 
-template <typename T> struct is_named_arg : std::false_type {};
-template <typename T> struct is_statically_named_arg : std::false_type {};
-
-template <typename T, typename Char>
-struct is_named_arg<named_arg<Char, T>> : std::true_type {};
-
-template <typename Char, typename T, typename... Tail,
-          FMT_ENABLE_IF(!is_named_arg<T>::value)>
+template <typename Char, typename T, typename... Tail>
 void init_named_args(named_arg_info<Char>* named_args, int arg_count,
                      int named_arg_count, const T&, const Tail&... args) {
   init_named_args(named_args, arg_count + 1, named_arg_count, args...);
 }
 
-template <typename Char, typename T, typename... Tail,
-          FMT_ENABLE_IF(is_named_arg<T>::value)>
+template <typename Char, typename T, typename... Tail>
 void init_named_args(named_arg_info<Char>* named_args, int arg_count,
-                     int named_arg_count, const T& arg, const Tail&... args) {
+                     int named_arg_count, const named_arg<Char, T>& arg,
+                     const Tail&... args) {
   named_args[named_arg_count++] = {arg.name, arg_count};
   init_named_args(named_args, arg_count + 1, named_arg_count, args...);
 }
 
 template <typename... Args>
-FMT_CONSTEXPR FMT_INLINE void init_named_args(std::nullptr_t, int, int,
-                                              const Args&...) {}
+FMT_INLINE void init_named_args(std::nullptr_t, int, int, const Args&...) {}
+
+template <typename T> struct is_named_arg : std::false_type {};
 
-template <bool B = false> constexpr auto count() -> size_t { return B ? 1 : 0; }
-template <bool B1, bool B2, bool... Tail> constexpr auto count() -> size_t {
+template <typename T, typename Char>
+struct is_named_arg<named_arg<Char, T>> : std::true_type {};
+
+template <bool B = false> constexpr size_t count() { return B ? 1 : 0; }
+template <bool B1, bool B2, bool... Tail> constexpr size_t count() {
   return (B1 ? 1 : 0) + count<B2, Tail...>();
 }
 
-template <typename... Args> constexpr auto count_named_args() -> size_t {
+template <typename... Args> constexpr size_t count_named_args() {
   return count<is_named_arg<Args>::value...>();
 }
 
-template <typename... Args>
-constexpr auto count_statically_named_args() -> size_t {
-  return count<is_statically_named_arg<Args>::value...>();
+enum class type {
+  none_type,
+  // Integer types should go first,
+  int_type,
+  uint_type,
+  long_long_type,
+  ulong_long_type,
+  int128_type,
+  uint128_type,
+  bool_type,
+  char_type,
+  last_integer_type = char_type,
+  // followed by floating-point types.
+  float_type,
+  double_type,
+  long_double_type,
+  last_numeric_type = long_double_type,
+  cstring_type,
+  string_type,
+  pointer_type,
+  custom_type
+};
+
+// Maps core type T to the corresponding type enum constant.
+template <typename T, typename Char>
+struct type_constant : std::integral_constant<type, type::custom_type> {};
+
+#define FMT_TYPE_CONSTANT(Type, constant) \
+  template <typename Char>                \
+  struct type_constant<Type, Char>        \
+      : std::integral_constant<type, type::constant> {}
+
+FMT_TYPE_CONSTANT(int, int_type);
+FMT_TYPE_CONSTANT(unsigned, uint_type);
+FMT_TYPE_CONSTANT(long long, long_long_type);
+FMT_TYPE_CONSTANT(unsigned long long, ulong_long_type);
+FMT_TYPE_CONSTANT(int128_t, int128_type);
+FMT_TYPE_CONSTANT(uint128_t, uint128_type);
+FMT_TYPE_CONSTANT(bool, bool_type);
+FMT_TYPE_CONSTANT(Char, char_type);
+FMT_TYPE_CONSTANT(float, float_type);
+FMT_TYPE_CONSTANT(double, double_type);
+FMT_TYPE_CONSTANT(long double, long_double_type);
+FMT_TYPE_CONSTANT(const Char*, cstring_type);
+FMT_TYPE_CONSTANT(basic_string_view<Char>, string_type);
+FMT_TYPE_CONSTANT(const void*, pointer_type);
+
+constexpr bool is_integral_type(type t) {
+  return t > type::none_type && t <= type::last_integer_type;
 }
 
-struct unformattable {};
-struct unformattable_char : unformattable {};
-struct unformattable_pointer : unformattable {};
+constexpr bool is_arithmetic_type(type t) {
+  return t > type::none_type && t <= type::last_numeric_type;
+}
 
 template <typename Char> struct string_value {
   const Char* data;
@@ -1236,8 +1041,8 @@ template <typename Char> struct named_arg_value {
 
 template <typename Context> struct custom_value {
   using parse_context = typename Context::parse_context_type;
-  void* value;
-  void (*format)(void* arg, parse_context& parse_ctx, Context& ctx);
+  const void* value;
+  void (*format)(const void* arg, parse_context& parse_ctx, Context& ctx);
 };
 
 // A formatting argument value.
@@ -1246,13 +1051,12 @@ template <typename Context> class value {
   using char_type = typename Context::char_type;
 
   union {
-    monostate no_value;
     int int_value;
     unsigned uint_value;
     long long long_long_value;
     unsigned long long ulong_long_value;
-    int128_opt int128_value;
-    uint128_opt uint128_value;
+    int128_t int128_value;
+    uint128_t uint128_value;
     bool bool_value;
     char_type char_value;
     float float_value;
@@ -1264,23 +1068,19 @@ template <typename Context> class value {
     named_arg_value<char_type> named_args;
   };
 
-  constexpr FMT_INLINE value() : no_value() {}
-  constexpr FMT_INLINE value(int val) : int_value(val) {}
+  constexpr FMT_INLINE value(int val = 0) : int_value(val) {}
   constexpr FMT_INLINE value(unsigned val) : uint_value(val) {}
-  constexpr FMT_INLINE value(long long val) : long_long_value(val) {}
-  constexpr FMT_INLINE value(unsigned long long val) : ulong_long_value(val) {}
-  FMT_INLINE value(int128_opt val) : int128_value(val) {}
-  FMT_INLINE value(uint128_opt val) : uint128_value(val) {}
-  constexpr FMT_INLINE value(float val) : float_value(val) {}
-  constexpr FMT_INLINE value(double val) : double_value(val) {}
+  FMT_INLINE value(long long val) : long_long_value(val) {}
+  FMT_INLINE value(unsigned long long val) : ulong_long_value(val) {}
+  FMT_INLINE value(int128_t val) : int128_value(val) {}
+  FMT_INLINE value(uint128_t val) : uint128_value(val) {}
+  FMT_INLINE value(float val) : float_value(val) {}
+  FMT_INLINE value(double val) : double_value(val) {}
   FMT_INLINE value(long double val) : long_double_value(val) {}
-  constexpr FMT_INLINE value(bool val) : bool_value(val) {}
-  constexpr FMT_INLINE value(char_type val) : char_value(val) {}
-  FMT_CONSTEXPR FMT_INLINE value(const char_type* val) {
-    string.data = val;
-    if (is_constant_evaluated()) string.size = {};
-  }
-  FMT_CONSTEXPR FMT_INLINE value(basic_string_view<char_type> val) {
+  FMT_INLINE value(bool val) : bool_value(val) {}
+  FMT_INLINE value(char_type val) : char_value(val) {}
+  FMT_INLINE value(const char_type* val) { string.data = val; }
+  FMT_INLINE value(basic_string_view<char_type> val) {
     string.data = val.data();
     string.size = val.size();
   }
@@ -1288,194 +1088,149 @@ template <typename Context> class value {
   FMT_INLINE value(const named_arg_info<char_type>* args, size_t size)
       : named_args{args, size} {}
 
-  template <typename T> FMT_CONSTEXPR20 FMT_INLINE value(T& val) {
-    using value_type = remove_const_t<T>;
-    custom.value = const_cast<value_type*>(std::addressof(val));
+  template <typename T> FMT_INLINE value(const T& val) {
+    custom.value = &val;
     // Get the formatter type through the context to allow different contexts
     // have different extension points, e.g. `formatter<T>` for `format` and
     // `printf_formatter<T>` for `printf`.
     custom.format = format_custom_arg<
-        value_type, typename Context::template formatter_type<value_type>>;
+        T, conditional_t<has_formatter<T, Context>::value,
+                         typename Context::template formatter_type<T>,
+                         fallback_formatter<T, char_type>>>;
   }
-  value(unformattable);
-  value(unformattable_char);
-  value(unformattable_pointer);
 
  private:
   // Formats an argument of a custom type, such as a user-defined class.
   template <typename T, typename Formatter>
-  static void format_custom_arg(void* arg,
+  static void format_custom_arg(const void* arg,
                                 typename Context::parse_context_type& parse_ctx,
                                 Context& ctx) {
-    auto f = Formatter();
+    Formatter f;
     parse_ctx.advance_to(f.parse(parse_ctx));
-    using qualified_type =
-        conditional_t<has_const_formatter<T, Context>(), const T, T>;
-    ctx.advance_to(f.format(*static_cast<qualified_type*>(arg), ctx));
+    ctx.advance_to(f.format(*static_cast<const T*>(arg), ctx));
   }
 };
 
+template <typename Context, typename T>
+FMT_CONSTEXPR basic_format_arg<Context> make_arg(const T& value);
+
 // To minimize the number of types we need to deal with, long is translated
 // either to int or to long long depending on its size.
 enum { long_short = sizeof(long) == sizeof(int) };
 using long_type = conditional_t<long_short, int, long long>;
 using ulong_type = conditional_t<long_short, unsigned, unsigned long long>;
 
-template <typename T> struct format_as_result {
-  template <typename U,
-            FMT_ENABLE_IF(std::is_enum<U>::value || std::is_class<U>::value)>
-  static auto map(U*) -> decltype(format_as(std::declval<U>()));
-  static auto map(...) -> void;
-
-  using type = decltype(map(static_cast<T*>(nullptr)));
-};
-template <typename T> using format_as_t = typename format_as_result<T>::type;
-
-template <typename T>
-struct has_format_as
-    : bool_constant<!std::is_same<format_as_t<T>, void>::value> {};
+struct unformattable {};
 
 // Maps formatting arguments to core types.
-// arg_mapper reports errors by returning unformattable instead of using
-// static_assert because it's used in the is_formattable trait.
 template <typename Context> struct arg_mapper {
   using char_type = typename Context::char_type;
 
-  FMT_CONSTEXPR FMT_INLINE auto map(signed char val) -> int { return val; }
-  FMT_CONSTEXPR FMT_INLINE auto map(unsigned char val) -> unsigned {
-    return val;
-  }
-  FMT_CONSTEXPR FMT_INLINE auto map(short val) -> int { return val; }
-  FMT_CONSTEXPR FMT_INLINE auto map(unsigned short val) -> unsigned {
-    return val;
-  }
-  FMT_CONSTEXPR FMT_INLINE auto map(int val) -> int { return val; }
-  FMT_CONSTEXPR FMT_INLINE auto map(unsigned val) -> unsigned { return val; }
-  FMT_CONSTEXPR FMT_INLINE auto map(long val) -> long_type { return val; }
-  FMT_CONSTEXPR FMT_INLINE auto map(unsigned long val) -> ulong_type {
-    return val;
-  }
-  FMT_CONSTEXPR FMT_INLINE auto map(long long val) -> long long { return val; }
-  FMT_CONSTEXPR FMT_INLINE auto map(unsigned long long val)
-      -> unsigned long long {
-    return val;
-  }
-  FMT_CONSTEXPR FMT_INLINE auto map(int128_opt val) -> int128_opt {
-    return val;
-  }
-  FMT_CONSTEXPR FMT_INLINE auto map(uint128_opt val) -> uint128_opt {
-    return val;
-  }
-  FMT_CONSTEXPR FMT_INLINE auto map(bool val) -> bool { return val; }
-
-  template <typename T, FMT_ENABLE_IF(std::is_same<T, char>::value ||
-                                      std::is_same<T, char_type>::value)>
-  FMT_CONSTEXPR FMT_INLINE auto map(T val) -> char_type {
+  FMT_CONSTEXPR int map(signed char val) { return val; }
+  FMT_CONSTEXPR unsigned map(unsigned char val) { return val; }
+  FMT_CONSTEXPR int map(short val) { return val; }
+  FMT_CONSTEXPR unsigned map(unsigned short val) { return val; }
+  FMT_CONSTEXPR int map(int val) { return val; }
+  FMT_CONSTEXPR unsigned map(unsigned val) { return val; }
+  FMT_CONSTEXPR long_type map(long val) { return val; }
+  FMT_CONSTEXPR ulong_type map(unsigned long val) { return val; }
+  FMT_CONSTEXPR long long map(long long val) { return val; }
+  FMT_CONSTEXPR unsigned long long map(unsigned long long val) { return val; }
+  FMT_CONSTEXPR int128_t map(int128_t val) { return val; }
+  FMT_CONSTEXPR uint128_t map(uint128_t val) { return val; }
+  FMT_CONSTEXPR bool map(bool val) { return val; }
+
+  template <typename T, FMT_ENABLE_IF(is_char<T>::value)>
+  FMT_CONSTEXPR char_type map(T val) {
+    static_assert(
+        std::is_same<T, char>::value || std::is_same<T, char_type>::value,
+        "mixing character types is disallowed");
     return val;
   }
-  template <typename T, enable_if_t<(std::is_same<T, wchar_t>::value ||
-#ifdef __cpp_char8_t
-                                     std::is_same<T, char8_t>::value ||
-#endif
-                                     std::is_same<T, char16_t>::value ||
-                                     std::is_same<T, char32_t>::value) &&
-                                        !std::is_same<T, char_type>::value,
-                                    int> = 0>
-  FMT_CONSTEXPR FMT_INLINE auto map(T) -> unformattable_char {
-    return {};
-  }
 
-  FMT_CONSTEXPR FMT_INLINE auto map(float val) -> float { return val; }
-  FMT_CONSTEXPR FMT_INLINE auto map(double val) -> double { return val; }
-  FMT_CONSTEXPR FMT_INLINE auto map(long double val) -> long double {
-    return val;
-  }
+  FMT_CONSTEXPR float map(float val) { return val; }
+  FMT_CONSTEXPR double map(double val) { return val; }
+  FMT_CONSTEXPR long double map(long double val) { return val; }
 
-  FMT_CONSTEXPR FMT_INLINE auto map(char_type* val) -> const char_type* {
-    return val;
-  }
-  FMT_CONSTEXPR FMT_INLINE auto map(const char_type* val) -> const char_type* {
-    return val;
-  }
-  template <typename T,
-            FMT_ENABLE_IF(is_string<T>::value && !std::is_pointer<T>::value &&
-                          std::is_same<char_type, char_t<T>>::value)>
-  FMT_CONSTEXPR FMT_INLINE auto map(const T& val)
-      -> basic_string_view<char_type> {
+  FMT_CONSTEXPR const char_type* map(char_type* val) { return val; }
+  FMT_CONSTEXPR const char_type* map(const char_type* val) { return val; }
+  template <typename T, FMT_ENABLE_IF(is_string<T>::value)>
+  FMT_CONSTEXPR basic_string_view<char_type> map(const T& val) {
+    static_assert(std::is_same<char_type, char_t<T>>::value,
+                  "mixing character types is disallowed");
     return to_string_view(val);
   }
   template <typename T,
-            FMT_ENABLE_IF(is_string<T>::value && !std::is_pointer<T>::value &&
-                          !std::is_same<char_type, char_t<T>>::value)>
-  FMT_CONSTEXPR FMT_INLINE auto map(const T&) -> unformattable_char {
-    return {};
-  }
-
-  FMT_CONSTEXPR FMT_INLINE auto map(void* val) -> const void* { return val; }
-  FMT_CONSTEXPR FMT_INLINE auto map(const void* val) -> const void* {
-    return val;
-  }
-  FMT_CONSTEXPR FMT_INLINE auto map(std::nullptr_t val) -> const void* {
-    return val;
+            FMT_ENABLE_IF(
+                std::is_constructible<basic_string_view<char_type>, T>::value &&
+                !is_string<T>::value && !has_formatter<T, Context>::value &&
+                !has_fallback_formatter<T, Context>::value)>
+  FMT_CONSTEXPR basic_string_view<char_type> map(const T& val) {
+    return basic_string_view<char_type>(val);
   }
-
-  // Use SFINAE instead of a const T* parameter to avoid a conflict with the
-  // array overload.
   template <
       typename T,
       FMT_ENABLE_IF(
-          std::is_pointer<T>::value || std::is_member_pointer<T>::value ||
-          std::is_function<typename std::remove_pointer<T>::type>::value ||
-          (std::is_array<T>::value &&
-           !std::is_convertible<T, const char_type*>::value))>
-  FMT_CONSTEXPR auto map(const T&) -> unformattable_pointer {
-    return {};
-  }
-
-  template <typename T, std::size_t N,
-            FMT_ENABLE_IF(!std::is_same<T, wchar_t>::value)>
-  FMT_CONSTEXPR FMT_INLINE auto map(const T (&values)[N]) -> const T (&)[N] {
-    return values;
+          std::is_constructible<std_string_view<char_type>, T>::value &&
+          !std::is_constructible<basic_string_view<char_type>, T>::value &&
+          !is_string<T>::value && !has_formatter<T, Context>::value &&
+          !has_fallback_formatter<T, Context>::value)>
+  FMT_CONSTEXPR basic_string_view<char_type> map(const T& val) {
+    return std_string_view<char_type>(val);
+  }
+  FMT_CONSTEXPR const char* map(const signed char* val) {
+    static_assert(std::is_same<char_type, char>::value, "invalid string type");
+    return reinterpret_cast<const char*>(val);
+  }
+  FMT_CONSTEXPR const char* map(const unsigned char* val) {
+    static_assert(std::is_same<char_type, char>::value, "invalid string type");
+    return reinterpret_cast<const char*>(val);
+  }
+  FMT_CONSTEXPR const char* map(signed char* val) {
+    const auto* const_val = val;
+    return map(const_val);
+  }
+  FMT_CONSTEXPR const char* map(unsigned char* val) {
+    const auto* const_val = val;
+    return map(const_val);
+  }
+
+  FMT_CONSTEXPR const void* map(void* val) { return val; }
+  FMT_CONSTEXPR const void* map(const void* val) { return val; }
+  FMT_CONSTEXPR const void* map(std::nullptr_t val) { return val; }
+  template <typename T> FMT_CONSTEXPR int map(const T*) {
+    // Formatting of arbitrary pointers is disallowed. If you want to output
+    // a pointer cast it to "void *" or "const void *". In particular, this
+    // forbids formatting of "[const] volatile char *" which is printed as bool
+    // by iostreams.
+    static_assert(!sizeof(T), "formatting of non-void pointers is disallowed");
+    return 0;
   }
 
-  // Only map owning types because mapping views can be unsafe.
-  template <typename T, typename U = format_as_t<T>,
-            FMT_ENABLE_IF(std::is_arithmetic<U>::value)>
-  FMT_CONSTEXPR FMT_INLINE auto map(const T& val) -> decltype(this->map(U())) {
-    return map(format_as(val));
+  template <typename T,
+            FMT_ENABLE_IF(std::is_enum<T>::value &&
+                          !has_formatter<T, Context>::value &&
+                          !has_fallback_formatter<T, Context>::value)>
+  FMT_CONSTEXPR auto map(const T& val)
+      -> decltype(std::declval<arg_mapper>().map(
+          static_cast<typename std::underlying_type<T>::type>(val))) {
+    return map(static_cast<typename std::underlying_type<T>::type>(val));
   }
-
-  template <typename T, typename U = remove_const_t<T>>
-  struct formattable : bool_constant<has_const_formatter<U, Context>() ||
-                                     (has_formatter<U, Context>::value &&
-                                      !std::is_const<T>::value)> {};
-
-  template <typename T, FMT_ENABLE_IF(formattable<T>::value)>
-  FMT_CONSTEXPR FMT_INLINE auto do_map(T& val) -> T& {
+  template <typename T,
+            FMT_ENABLE_IF(!is_string<T>::value && !is_char<T>::value &&
+                          (has_formatter<T, Context>::value ||
+                           has_fallback_formatter<T, Context>::value))>
+  FMT_CONSTEXPR const T& map(const T& val) {
     return val;
   }
-  template <typename T, FMT_ENABLE_IF(!formattable<T>::value)>
-  FMT_CONSTEXPR FMT_INLINE auto do_map(T&) -> unformattable {
-    return {};
-  }
-
-  template <typename T, typename U = remove_const_t<T>,
-            FMT_ENABLE_IF((std::is_class<U>::value || std::is_enum<U>::value ||
-                           std::is_union<U>::value) &&
-                          !is_string<U>::value && !is_char<U>::value &&
-                          !is_named_arg<U>::value &&
-                          !std::is_arithmetic<format_as_t<U>>::value)>
-  FMT_CONSTEXPR FMT_INLINE auto map(T& val) -> decltype(this->do_map(val)) {
-    return do_map(val);
-  }
 
-  template <typename T, FMT_ENABLE_IF(is_named_arg<T>::value)>
-  FMT_CONSTEXPR FMT_INLINE auto map(const T& named_arg)
-      -> decltype(this->map(named_arg.value)) {
-    return map(named_arg.value);
+  template <typename T>
+  FMT_CONSTEXPR auto map(const named_arg<char_type, T>& val)
+      -> decltype(std::declval<arg_mapper>().map(val.value)) {
+    return map(val.value);
   }
 
-  auto map(...) -> unformattable { return {}; }
+  unformattable map(...) { return {}; }
 };
 
 // A type constant after applying arg_mapper<Context>.
@@ -1489,122 +1244,7 @@ enum { packed_arg_bits = 4 };
 enum { max_packed_args = 62 / packed_arg_bits };
 enum : unsigned long long { is_unpacked_bit = 1ULL << 63 };
 enum : unsigned long long { has_named_args_bit = 1ULL << 62 };
-
-template <typename Char, typename InputIt>
-auto copy_str(InputIt begin, InputIt end, appender out) -> appender {
-  get_container(out).append(begin, end);
-  return out;
-}
-template <typename Char, typename InputIt>
-auto copy_str(InputIt begin, InputIt end,
-              std::back_insert_iterator<std::string> out)
-    -> std::back_insert_iterator<std::string> {
-  get_container(out).append(begin, end);
-  return out;
-}
-
-template <typename Char, typename R, typename OutputIt>
-FMT_CONSTEXPR auto copy_str(R&& rng, OutputIt out) -> OutputIt {
-  return detail::copy_str<Char>(rng.begin(), rng.end(), out);
-}
-
-#if FMT_GCC_VERSION && FMT_GCC_VERSION < 500
-// A workaround for gcc 4.8 to make void_t work in a SFINAE context.
-template <typename...> struct void_t_impl {
-  using type = void;
-};
-template <typename... T> using void_t = typename void_t_impl<T...>::type;
-#else
-template <typename...> using void_t = void;
-#endif
-
-template <typename It, typename T, typename Enable = void>
-struct is_output_iterator : std::false_type {};
-
-template <typename It, typename T>
-struct is_output_iterator<
-    It, T,
-    void_t<typename std::iterator_traits<It>::iterator_category,
-           decltype(*std::declval<It>() = std::declval<T>())>>
-    : std::true_type {};
-
-template <typename It> struct is_back_insert_iterator : std::false_type {};
-template <typename Container>
-struct is_back_insert_iterator<std::back_insert_iterator<Container>>
-    : std::true_type {};
-
-// A type-erased reference to an std::locale to avoid a heavy <locale> include.
-class locale_ref {
- private:
-  const void* locale_;  // A type-erased pointer to std::locale.
-
- public:
-  constexpr FMT_INLINE locale_ref() : locale_(nullptr) {}
-  template <typename Locale> explicit locale_ref(const Locale& loc);
-
-  explicit operator bool() const noexcept { return locale_ != nullptr; }
-
-  template <typename Locale> auto get() const -> Locale;
-};
-
-template <typename> constexpr auto encode_types() -> unsigned long long {
-  return 0;
-}
-
-template <typename Context, typename Arg, typename... Args>
-constexpr auto encode_types() -> unsigned long long {
-  return static_cast<unsigned>(mapped_type_constant<Arg, Context>::value) |
-         (encode_types<Context, Args...>() << packed_arg_bits);
-}
-
-#if defined(__cpp_if_constexpr)
-// This type is intentionally undefined, only used for errors
-template <typename T, typename Char> struct type_is_unformattable_for;
-#endif
-
-template <bool PACKED, typename Context, typename T, FMT_ENABLE_IF(PACKED)>
-FMT_CONSTEXPR FMT_INLINE auto make_arg(T& val) -> value<Context> {
-  using arg_type = remove_cvref_t<decltype(arg_mapper<Context>().map(val))>;
-
-  constexpr bool formattable_char =
-      !std::is_same<arg_type, unformattable_char>::value;
-  static_assert(formattable_char, "Mixing character types is disallowed.");
-
-  // Formatting of arbitrary pointers is disallowed. If you want to format a
-  // pointer cast it to `void*` or `const void*`. In particular, this forbids
-  // formatting of `[const] volatile char*` printed as bool by iostreams.
-  constexpr bool formattable_pointer =
-      !std::is_same<arg_type, unformattable_pointer>::value;
-  static_assert(formattable_pointer,
-                "Formatting of non-void pointers is disallowed.");
-
-  constexpr bool formattable = !std::is_same<arg_type, unformattable>::value;
-#if defined(__cpp_if_constexpr)
-  if constexpr (!formattable) {
-    type_is_unformattable_for<T, typename Context::char_type> _;
-  }
-#endif
-  static_assert(
-      formattable,
-      "Cannot format an argument. To make type T formattable provide a "
-      "formatter<T> specialization: https://fmt.dev/latest/api.html#udt");
-  return {arg_mapper<Context>().map(val)};
-}
-
-template <typename Context, typename T>
-FMT_CONSTEXPR auto make_arg(T& val) -> basic_format_arg<Context> {
-  auto arg = basic_format_arg<Context>();
-  arg.type_ = mapped_type_constant<T, Context>::value;
-  arg.value_ = make_arg<true, Context>(val);
-  return arg;
-}
-
-template <bool PACKED, typename Context, typename T, FMT_ENABLE_IF(!PACKED)>
-FMT_CONSTEXPR inline auto make_arg(T& val) -> basic_format_arg<Context> {
-  return make_arg<Context>(val);
-}
 }  // namespace detail
-FMT_BEGIN_EXPORT
 
 // A formatting argument. It is a trivially copyable/constructible type to
 // allow storage in basic_memory_buffer.
@@ -1614,8 +1254,8 @@ template <typename Context> class basic_format_arg {
   detail::type type_;
 
   template <typename ContextType, typename T>
-  friend FMT_CONSTEXPR auto detail::make_arg(T& value)
-      -> basic_format_arg<ContextType>;
+  friend FMT_CONSTEXPR basic_format_arg<ContextType> detail::make_arg(
+      const T& value);
 
   template <typename Visitor, typename Ctx>
   friend FMT_CONSTEXPR auto visit_format_arg(Visitor&& vis,
@@ -1649,16 +1289,14 @@ template <typename Context> class basic_format_arg {
 
   constexpr basic_format_arg() : type_(detail::type::none_type) {}
 
-  constexpr explicit operator bool() const noexcept {
+  constexpr explicit operator bool() const FMT_NOEXCEPT {
     return type_ != detail::type::none_type;
   }
 
-  auto type() const -> detail::type { return type_; }
+  detail::type type() const { return type_; }
 
-  auto is_integral() const -> bool { return detail::is_integral_type(type_); }
-  auto is_arithmetic() const -> bool {
-    return detail::is_arithmetic_type(type_);
-  }
+  bool is_integral() const { return detail::is_integral_type(type_); }
+  bool is_arithmetic() const { return detail::is_arithmetic_type(type_); }
 };
 
 /**
@@ -1668,10 +1306,10 @@ template <typename Context> class basic_format_arg {
   ``vis(value)`` will be called with the value of type ``double``.
   \endrst
  */
-// DEPRECATED!
 template <typename Visitor, typename Context>
-FMT_CONSTEXPR FMT_INLINE auto visit_format_arg(
+FMT_CONSTEXPR_DECL FMT_INLINE auto visit_format_arg(
     Visitor&& vis, const basic_format_arg<Context>& arg) -> decltype(vis(0)) {
+  using char_type = typename Context::char_type;
   switch (arg.type_) {
   case detail::type::none_type:
     break;
@@ -1683,10 +1321,16 @@ FMT_CONSTEXPR FMT_INLINE auto visit_format_arg(
     return vis(arg.value_.long_long_value);
   case detail::type::ulong_long_type:
     return vis(arg.value_.ulong_long_value);
+#if FMT_USE_INT128
+  case detail::type::int128_type:
+    return vis(arg.value_.int128_value);
+  case detail::type::uint128_type:
+    return vis(arg.value_.uint128_value);
+#else
   case detail::type::int128_type:
-    return vis(detail::convert_for_visit(arg.value_.int128_value));
   case detail::type::uint128_type:
-    return vis(detail::convert_for_visit(arg.value_.uint128_value));
+    break;
+#endif
   case detail::type::bool_type:
     return vis(arg.value_.bool_value);
   case detail::type::char_type:
@@ -1700,8 +1344,8 @@ FMT_CONSTEXPR FMT_INLINE auto visit_format_arg(
   case detail::type::cstring_type:
     return vis(arg.value_.string.data);
   case detail::type::string_type:
-    using sv = basic_string_view<typename Context::char_type>;
-    return vis(sv(arg.value_.string.data, arg.value_.string.size));
+    return vis(basic_string_view<char_type>(arg.value_.string.data,
+                                            arg.value_.string.size));
   case detail::type::pointer_type:
     return vis(arg.value_.pointer);
   case detail::type::custom_type:
@@ -1710,66 +1354,194 @@ FMT_CONSTEXPR FMT_INLINE auto visit_format_arg(
   return vis(monostate());
 }
 
-// Formatting context.
-template <typename OutputIt, typename Char> class basic_format_context {
- private:
-  OutputIt out_;
-  basic_format_args<basic_format_context> args_;
-  detail::locale_ref loc_;
+template <typename T> struct formattable : std::false_type {};
 
- public:
-  using iterator = OutputIt;
-  using format_arg = basic_format_arg<basic_format_context>;
-  using format_args = basic_format_args<basic_format_context>;
-  using parse_context_type = basic_format_parse_context<Char>;
-  template <typename T> using formatter_type = formatter<T, Char>;
+namespace detail {
 
-  /** The character type for the output. */
-  using char_type = Char;
+// A workaround for gcc 4.8 to make void_t work in a SFINAE context.
+template <typename... Ts> struct void_t_impl { using type = void; };
+template <typename... Ts>
+using void_t = typename detail::void_t_impl<Ts...>::type;
 
-  basic_format_context(basic_format_context&&) = default;
-  basic_format_context(const basic_format_context&) = delete;
-  void operator=(const basic_format_context&) = delete;
-  /**
-    Constructs a ``basic_format_context`` object. References to the arguments
-    are stored in the object so make sure they have appropriate lifetimes.
-   */
-  constexpr basic_format_context(OutputIt out, format_args ctx_args,
-                                 detail::locale_ref loc = {})
-      : out_(out), args_(ctx_args), loc_(loc) {}
+template <typename It, typename T, typename Enable = void>
+struct is_output_iterator : std::false_type {};
 
-  constexpr auto arg(int id) const -> format_arg { return args_.get(id); }
-  FMT_CONSTEXPR auto arg(basic_string_view<Char> name) -> format_arg {
-    return args_.get(name);
-  }
-  FMT_CONSTEXPR auto arg_id(basic_string_view<Char> name) -> int {
-    return args_.get_id(name);
-  }
-  auto args() const -> const format_args& { return args_; }
+template <typename It, typename T>
+struct is_output_iterator<
+    It, T,
+    void_t<typename std::iterator_traits<It>::iterator_category,
+           decltype(*std::declval<It>() = std::declval<T>())>>
+    : std::true_type {};
 
-  FMT_CONSTEXPR auto error_handler() -> detail::error_handler { return {}; }
+template <typename OutputIt>
+struct is_back_insert_iterator : std::false_type {};
+template <typename Container>
+struct is_back_insert_iterator<std::back_insert_iterator<Container>>
+    : std::true_type {};
+
+template <typename OutputIt>
+struct is_contiguous_back_insert_iterator : std::false_type {};
+template <typename Container>
+struct is_contiguous_back_insert_iterator<std::back_insert_iterator<Container>>
+    : is_contiguous<Container> {};
+template <typename Char>
+struct is_contiguous_back_insert_iterator<buffer_appender<Char>>
+    : std::true_type {};
+
+// A type-erased reference to an std::locale to avoid heavy <locale> include.
+class locale_ref {
+ private:
+  const void* locale_;  // A type-erased pointer to std::locale.
+
+ public:
+  locale_ref() : locale_(nullptr) {}
+  template <typename Locale> explicit locale_ref(const Locale& loc);
+
+  explicit operator bool() const FMT_NOEXCEPT { return locale_ != nullptr; }
+
+  template <typename Locale> Locale get() const;
+};
+
+template <typename> constexpr unsigned long long encode_types() { return 0; }
+
+template <typename Context, typename Arg, typename... Args>
+constexpr unsigned long long encode_types() {
+  return static_cast<unsigned>(mapped_type_constant<Arg, Context>::value) |
+         (encode_types<Context, Args...>() << packed_arg_bits);
+}
+
+template <typename Context, typename T>
+FMT_CONSTEXPR basic_format_arg<Context> make_arg(const T& value) {
+  basic_format_arg<Context> arg;
+  arg.type_ = mapped_type_constant<T, Context>::value;
+  arg.value_ = arg_mapper<Context>().map(value);
+  return arg;
+}
+
+template <typename T> int check(unformattable) {
+  static_assert(
+      formattable<T>(),
+      "Cannot format an argument. To make type T formattable provide a "
+      "formatter<T> specialization: https://fmt.dev/latest/api.html#udt");
+  return 0;
+}
+template <typename T, typename U> inline const U& check(const U& val) {
+  return val;
+}
+
+// The type template parameter is there to avoid an ODR violation when using
+// a fallback formatter in one translation unit and an implicit conversion in
+// another (not recommended).
+template <bool IS_PACKED, typename Context, type, typename T,
+          FMT_ENABLE_IF(IS_PACKED)>
+inline value<Context> make_arg(const T& val) {
+  return check<T>(arg_mapper<Context>().map(val));
+}
+
+template <bool IS_PACKED, typename Context, type, typename T,
+          FMT_ENABLE_IF(!IS_PACKED)>
+inline basic_format_arg<Context> make_arg(const T& value) {
+  return make_arg<Context>(value);
+}
+
+template <typename T> struct is_reference_wrapper : std::false_type {};
+template <typename T>
+struct is_reference_wrapper<std::reference_wrapper<T>> : std::true_type {};
+
+template <typename T> const T& unwrap(const T& v) { return v; }
+template <typename T> const T& unwrap(const std::reference_wrapper<T>& v) {
+  return static_cast<const T&>(v);
+}
+
+class dynamic_arg_list {
+  // Workaround for clang's -Wweak-vtables. Unlike for regular classes, for
+  // templates it doesn't complain about inability to deduce single translation
+  // unit for placing vtable. So storage_node_base is made a fake template.
+  template <typename = void> struct node {
+    virtual ~node() = default;
+    std::unique_ptr<node<>> next;
+  };
+
+  template <typename T> struct typed_node : node<> {
+    T value;
+
+    template <typename Arg>
+    FMT_CONSTEXPR typed_node(const Arg& arg) : value(arg) {}
+
+    template <typename Char>
+    FMT_CONSTEXPR typed_node(const basic_string_view<Char>& arg)
+        : value(arg.data(), arg.size()) {}
+  };
+
+  std::unique_ptr<node<>> head_;
+
+ public:
+  template <typename T, typename Arg> const T& push(const Arg& arg) {
+    auto new_node = std::unique_ptr<typed_node<T>>(new typed_node<T>(arg));
+    auto& value = new_node->value;
+    new_node->next = std::move(head_);
+    head_ = std::move(new_node);
+    return value;
+  }
+};
+}  // namespace detail
+
+// Formatting context.
+template <typename OutputIt, typename Char> class basic_format_context {
+ public:
+  /** The character type for the output. */
+  using char_type = Char;
+
+ private:
+  OutputIt out_;
+  basic_format_args<basic_format_context> args_;
+  detail::locale_ref loc_;
+
+ public:
+  using iterator = OutputIt;
+  using format_arg = basic_format_arg<basic_format_context>;
+  using parse_context_type = basic_format_parse_context<Char>;
+  template <typename T> using formatter_type = formatter<T, char_type>;
+
+  basic_format_context(const basic_format_context&) = delete;
+  void operator=(const basic_format_context&) = delete;
+  /**
+   Constructs a ``basic_format_context`` object. References to the arguments are
+   stored in the object so make sure they have appropriate lifetimes.
+   */
+  basic_format_context(OutputIt out,
+                       basic_format_args<basic_format_context> ctx_args,
+                       detail::locale_ref loc = detail::locale_ref())
+      : out_(out), args_(ctx_args), loc_(loc) {}
+
+  format_arg arg(int id) const { return args_.get(id); }
+  format_arg arg(basic_string_view<char_type> name) { return args_.get(name); }
+  int arg_id(basic_string_view<char_type> name) { return args_.get_id(name); }
+  const basic_format_args<basic_format_context>& args() const { return args_; }
+
+  detail::error_handler error_handler() { return {}; }
   void on_error(const char* message) { error_handler().on_error(message); }
 
   // Returns an iterator to the beginning of the output range.
-  FMT_CONSTEXPR auto out() -> iterator { return out_; }
+  iterator out() { return out_; }
 
   // Advances the begin iterator to ``it``.
   void advance_to(iterator it) {
     if (!detail::is_back_insert_iterator<iterator>()) out_ = it;
   }
 
-  FMT_CONSTEXPR auto locale() -> detail::locale_ref { return loc_; }
+  detail::locale_ref locale() { return loc_; }
 };
 
 template <typename Char>
 using buffer_context =
     basic_format_context<detail::buffer_appender<Char>, Char>;
 using format_context = buffer_context<char>;
+using wformat_context = buffer_context<wchar_t>;
 
-template <typename T, typename Char = char>
-using is_formattable = bool_constant<!std::is_base_of<
-    detail::unformattable, decltype(detail::arg_mapper<buffer_context<Char>>()
-                                        .map(std::declval<T&>()))>::value>;
+// Workaround an alias issue: https://stackoverflow.com/q/62767544/471164.
+#define FMT_BUFFER_CONTEXT(Char) \
+  basic_format_context<detail::buffer_appender<Char>, Char>
 
 /**
   \rst
@@ -1787,7 +1559,7 @@ class format_arg_store
 {
  private:
   static const size_t num_args = sizeof...(Args);
-  static constexpr size_t num_named_args = detail::count_named_args<Args...>();
+  static const size_t num_named_args = detail::count_named_args<Args...>();
   static const bool is_packed = num_args <= detail::max_packed_args;
 
   using value_type = conditional_t<is_packed, detail::value<Context>,
@@ -1807,15 +1579,15 @@ class format_arg_store
            : 0);
 
  public:
-  template <typename... T>
-  FMT_CONSTEXPR FMT_INLINE format_arg_store(T&... args)
+  format_arg_store(const Args&... args)
       :
 #if FMT_GCC_VERSION && FMT_GCC_VERSION < 409
         basic_format_args<Context>(*this),
 #endif
-        data_{detail::make_arg<is_packed, Context>(args)...} {
-    if (detail::const_check(num_named_args != 0))
-      detail::init_named_args(data_.named_args(), 0, 0, args...);
+        data_{detail::make_arg<
+            is_packed, Context,
+            detail::mapped_type_constant<Args, Context>::value>(args)...} {
+    detail::init_named_args(data_.named_args(), 0, 0, args...);
   }
 };
 
@@ -1823,22 +1595,41 @@ class format_arg_store
   \rst
   Constructs a `~fmt::format_arg_store` object that contains references to
   arguments and can be implicitly converted to `~fmt::format_args`. `Context`
-  can be omitted in which case it defaults to `~fmt::format_context`.
+  can be omitted in which case it defaults to `~fmt::context`.
   See `~fmt::arg` for lifetime considerations.
   \endrst
  */
-// Arguments are taken by lvalue references to avoid some lifetime issues.
-template <typename Context = format_context, typename... T>
-constexpr auto make_format_args(T&... args)
-    -> format_arg_store<Context, remove_cvref_t<T>...> {
+template <typename Context = format_context, typename... Args>
+inline format_arg_store<Context, Args...> make_format_args(
+    const Args&... args) {
   return {args...};
 }
 
 /**
   \rst
-  Returns a named argument to be used in a formatting function.
-  It should only be used in a call to a formatting function or
-  `dynamic_format_arg_store::push_back`.
+  Constructs a `~fmt::format_arg_store` object that contains references
+  to arguments and can be implicitly converted to `~fmt::format_args`.
+  If ``format_str`` is a compile-time string then `make_args_checked` checks
+  its validity at compile time.
+  \endrst
+ */
+template <typename... Args, typename S, typename Char = char_t<S>>
+inline auto make_args_checked(const S& format_str,
+                              const remove_reference_t<Args>&... args)
+    -> format_arg_store<buffer_context<Char>, remove_reference_t<Args>...> {
+  static_assert(
+      detail::count<(
+              std::is_base_of<detail::view, remove_reference_t<Args>>::value &&
+              std::is_reference<Args>::value)...>() == 0,
+      "passing views as lvalues is disallowed");
+  detail::check_format_string<Args...>(format_str);
+  return {args...};
+}
+
+/**
+  \rst
+  Returns a named argument to be used in a formatting function. It should only
+  be used in a call to a formatting function.
 
   **Example**::
 
@@ -1846,11 +1637,183 @@ constexpr auto make_format_args(T&... args)
   \endrst
  */
 template <typename Char, typename T>
-inline auto arg(const Char* name, const T& arg) -> detail::named_arg<Char, T> {
+inline detail::named_arg<Char, T> arg(const Char* name, const T& arg) {
   static_assert(!detail::is_named_arg<T>(), "nested named arguments");
   return {name, arg};
 }
-FMT_END_EXPORT
+
+/**
+  \rst
+  A dynamic version of `fmt::format_arg_store`.
+  It's equipped with a storage to potentially temporary objects which lifetimes
+  could be shorter than the format arguments object.
+
+  It can be implicitly converted into `~fmt::basic_format_args` for passing
+  into type-erased formatting functions such as `~fmt::vformat`.
+  \endrst
+ */
+template <typename Context>
+class dynamic_format_arg_store
+#if FMT_GCC_VERSION && FMT_GCC_VERSION < 409
+    // Workaround a GCC template argument substitution bug.
+    : public basic_format_args<Context>
+#endif
+{
+ private:
+  using char_type = typename Context::char_type;
+
+  template <typename T> struct need_copy {
+    static constexpr detail::type mapped_type =
+        detail::mapped_type_constant<T, Context>::value;
+
+    enum {
+      value = !(detail::is_reference_wrapper<T>::value ||
+                std::is_same<T, basic_string_view<char_type>>::value ||
+                std::is_same<T, detail::std_string_view<char_type>>::value ||
+                (mapped_type != detail::type::cstring_type &&
+                 mapped_type != detail::type::string_type &&
+                 mapped_type != detail::type::custom_type))
+    };
+  };
+
+  template <typename T>
+  using stored_type = conditional_t<detail::is_string<T>::value,
+                                    std::basic_string<char_type>, T>;
+
+  // Storage of basic_format_arg must be contiguous.
+  std::vector<basic_format_arg<Context>> data_;
+  std::vector<detail::named_arg_info<char_type>> named_info_;
+
+  // Storage of arguments not fitting into basic_format_arg must grow
+  // without relocation because items in data_ refer to it.
+  detail::dynamic_arg_list dynamic_args_;
+
+  friend class basic_format_args<Context>;
+
+  unsigned long long get_types() const {
+    return detail::is_unpacked_bit | data_.size() |
+           (named_info_.empty()
+                ? 0ULL
+                : static_cast<unsigned long long>(detail::has_named_args_bit));
+  }
+
+  const basic_format_arg<Context>* data() const {
+    return named_info_.empty() ? data_.data() : data_.data() + 1;
+  }
+
+  template <typename T> void emplace_arg(const T& arg) {
+    data_.emplace_back(detail::make_arg<Context>(arg));
+  }
+
+  template <typename T>
+  void emplace_arg(const detail::named_arg<char_type, T>& arg) {
+    if (named_info_.empty()) {
+      constexpr const detail::named_arg_info<char_type>* zero_ptr{nullptr};
+      data_.insert(data_.begin(), {zero_ptr, 0});
+    }
+    data_.emplace_back(detail::make_arg<Context>(detail::unwrap(arg.value)));
+    auto pop_one = [](std::vector<basic_format_arg<Context>>* data) {
+      data->pop_back();
+    };
+    std::unique_ptr<std::vector<basic_format_arg<Context>>, decltype(pop_one)>
+        guard{&data_, pop_one};
+    named_info_.push_back({arg.name, static_cast<int>(data_.size() - 2u)});
+    data_[0].value_.named_args = {named_info_.data(), named_info_.size()};
+    guard.release();
+  }
+
+ public:
+  /**
+    \rst
+    Adds an argument into the dynamic store for later passing to a formatting
+    function.
+
+    Note that custom types and string types (but not string views) are copied
+    into the store dynamically allocating memory if necessary.
+
+    **Example**::
+
+      fmt::dynamic_format_arg_store<fmt::format_context> store;
+      store.push_back(42);
+      store.push_back("abc");
+      store.push_back(1.5f);
+      std::string result = fmt::vformat("{} and {} and {}", store);
+    \endrst
+  */
+  template <typename T> void push_back(const T& arg) {
+    if (detail::const_check(need_copy<T>::value))
+      emplace_arg(dynamic_args_.push<stored_type<T>>(arg));
+    else
+      emplace_arg(detail::unwrap(arg));
+  }
+
+  /**
+    \rst
+    Adds a reference to the argument into the dynamic store for later passing to
+    a formatting function. Supports named arguments wrapped in
+    ``std::reference_wrapper`` via ``std::ref()``/``std::cref()``.
+
+    **Example**::
+
+      fmt::dynamic_format_arg_store<fmt::format_context> store;
+      char str[] = "1234567890";
+      store.push_back(std::cref(str));
+      int a1_val{42};
+      auto a1 = fmt::arg("a1_", a1_val);
+      store.push_back(std::cref(a1));
+
+      // Changing str affects the output but only for string and custom types.
+      str[0] = 'X';
+
+      std::string result = fmt::vformat("{} and {a1_}");
+      assert(result == "X234567890 and 42");
+    \endrst
+  */
+  template <typename T> void push_back(std::reference_wrapper<T> arg) {
+    static_assert(
+        detail::is_named_arg<typename std::remove_cv<T>::type>::value ||
+            need_copy<T>::value,
+        "objects of built-in types and string views are always copied");
+    emplace_arg(arg.get());
+  }
+
+  /**
+    Adds named argument into the dynamic store for later passing to a formatting
+    function. ``std::reference_wrapper`` is supported to avoid copying of the
+    argument.
+  */
+  template <typename T>
+  void push_back(const detail::named_arg<char_type, T>& arg) {
+    const char_type* arg_name =
+        dynamic_args_.push<std::basic_string<char_type>>(arg.name).c_str();
+    if (detail::const_check(need_copy<T>::value)) {
+      emplace_arg(
+          fmt::arg(arg_name, dynamic_args_.push<stored_type<T>>(arg.value)));
+    } else {
+      emplace_arg(fmt::arg(arg_name, arg.value));
+    }
+  }
+
+  /** Erase all elements from the store */
+  void clear() {
+    data_.clear();
+    named_info_.clear();
+    dynamic_args_ = detail::dynamic_arg_list();
+  }
+
+  /**
+    \rst
+    Reserves space to store at least *new_cap* arguments including
+    *new_cap_named* named arguments.
+    \endrst
+  */
+  void reserve(size_t new_cap, size_t new_cap_named) {
+    FMT_ASSERT(new_cap >= new_cap_named,
+               "Set of arguments includes set of named arguments");
+    data_.reserve(new_cap);
+    named_info_.reserve(new_cap_named);
+  }
+};
 
 /**
   \rst
@@ -1859,7 +1822,7 @@ FMT_END_EXPORT
   ``vformat``::
 
     void vlog(string_view format_str, format_args args);  // OK
-    format_args args = make_format_args();  // Error: dangling reference
+    format_args args = make_format_args(42);  // Error: dangling reference
   \endrst
  */
 template <typename Context> class basic_format_args {
@@ -1883,27 +1846,25 @@ template <typename Context> class basic_format_args {
     const format_arg* args_;
   };
 
-  constexpr auto is_packed() const -> bool {
-    return (desc_ & detail::is_unpacked_bit) == 0;
-  }
-  auto has_named_args() const -> bool {
+  bool is_packed() const { return (desc_ & detail::is_unpacked_bit) == 0; }
+  bool has_named_args() const {
     return (desc_ & detail::has_named_args_bit) != 0;
   }
 
-  FMT_CONSTEXPR auto type(int index) const -> detail::type {
+  detail::type type(int index) const {
     int shift = index * detail::packed_arg_bits;
     unsigned int mask = (1 << detail::packed_arg_bits) - 1;
     return static_cast<detail::type>((desc_ >> shift) & mask);
   }
 
-  constexpr FMT_INLINE basic_format_args(unsigned long long desc,
-                                         const detail::value<Context>* values)
+  basic_format_args(unsigned long long desc,
+                    const detail::value<Context>* values)
       : desc_(desc), values_(values) {}
-  constexpr basic_format_args(unsigned long long desc, const format_arg* args)
+  basic_format_args(unsigned long long desc, const format_arg* args)
       : desc_(desc), args_(args) {}
 
  public:
-  constexpr basic_format_args() : desc_(0), args_(nullptr) {}
+  basic_format_args() : desc_(0) {}
 
   /**
    \rst
@@ -1911,10 +1872,8 @@ template <typename Context> class basic_format_args {
    \endrst
    */
   template <typename... Args>
-  constexpr FMT_INLINE basic_format_args(
-      const format_arg_store<Context, Args...>& store)
-      : basic_format_args(format_arg_store<Context, Args...>::desc,
-                          store.data_.args()) {}
+  FMT_INLINE basic_format_args(const format_arg_store<Context, Args...>& store)
+      : basic_format_args(store.desc, store.data_.args()) {}
 
   /**
    \rst
@@ -1922,8 +1881,7 @@ template <typename Context> class basic_format_args {
    `~fmt::dynamic_format_arg_store`.
    \endrst
    */
-  constexpr FMT_INLINE basic_format_args(
-      const dynamic_format_arg_store<Context>& store)
+  FMT_INLINE basic_format_args(const dynamic_format_arg_store<Context>& store)
       : basic_format_args(store.get_types(), store.data()) {}
 
   /**
@@ -1931,12 +1889,12 @@ template <typename Context> class basic_format_args {
    Constructs a `basic_format_args` object from a dynamic set of arguments.
    \endrst
    */
-  constexpr basic_format_args(const format_arg* args, int count)
+  basic_format_args(const format_arg* args, int count)
       : basic_format_args(detail::is_unpacked_bit | detail::to_unsigned(count),
                           args) {}
 
   /** Returns the argument with the specified id. */
-  FMT_CONSTEXPR auto get(int id) const -> format_arg {
+  format_arg get(int id) const {
     format_arg arg;
     if (!is_packed()) {
       if (id < max_size()) arg = args_[id];
@@ -1949,14 +1907,12 @@ template <typename Context> class basic_format_args {
     return arg;
   }
 
-  template <typename Char>
-  auto get(basic_string_view<Char> name) const -> format_arg {
+  template <typename Char> format_arg get(basic_string_view<Char> name) const {
     int id = get_id(name);
     return id >= 0 ? get(id) : format_arg();
   }
 
-  template <typename Char>
-  auto get_id(basic_string_view<Char> name) const -> int {
+  template <typename Char> int get_id(basic_string_view<Char> name) const {
     if (!has_named_args()) return -1;
     const auto& named_args =
         (is_packed() ? values_[-1] : args_[-1].value_).named_args;
@@ -1966,732 +1922,49 @@ template <typename Context> class basic_format_args {
     return -1;
   }
 
-  auto max_size() const -> int {
+  int max_size() const {
     unsigned long long max_packed = detail::max_packed_args;
     return static_cast<int>(is_packed() ? max_packed
                                         : desc_ & ~detail::is_unpacked_bit);
   }
 };
 
+#ifdef FMT_ARM_ABI_COMPATIBILITY
 /** An alias to ``basic_format_args<format_context>``. */
-// A separate type would result in shorter symbols but break ABI compatibility
+// Separate types would result in shorter symbols but break ABI compatibility
 // between clang and gcc on ARM (#1919).
-FMT_EXPORT using format_args = basic_format_args<format_context>;
-
-// We cannot use enum classes as bit fields because of a gcc bug, so we put them
-// in namespaces instead (https://gcc.gnu.org/bugzilla/show_bug.cgi?id=61414).
-// Additionally, if an underlying type is specified, older gcc incorrectly warns
-// that the type is too small. Both bugs are fixed in gcc 9.3.
-#if FMT_GCC_VERSION && FMT_GCC_VERSION < 903
-#  define FMT_ENUM_UNDERLYING_TYPE(type)
+using format_args = basic_format_args<format_context>;
+using wformat_args = basic_format_args<wformat_context>;
 #else
-#  define FMT_ENUM_UNDERLYING_TYPE(type) : type
-#endif
-namespace align {
-enum type FMT_ENUM_UNDERLYING_TYPE(unsigned char){none, left, right, center,
-                                                  numeric};
-}
-using align_t = align::type;
-namespace sign {
-enum type FMT_ENUM_UNDERLYING_TYPE(unsigned char){none, minus, plus, space};
-}
-using sign_t = sign::type;
-
-namespace detail {
-
-// Workaround an array initialization issue in gcc 4.8.
-template <typename Char> struct fill_t {
- private:
-  enum { max_size = 4 };
-  Char data_[max_size] = {Char(' '), Char(0), Char(0), Char(0)};
-  unsigned char size_ = 1;
-
- public:
-  FMT_CONSTEXPR void operator=(basic_string_view<Char> s) {
-    auto size = s.size();
-    FMT_ASSERT(size <= max_size, "invalid fill");
-    for (size_t i = 0; i < size; ++i) data_[i] = s[i];
-    size_ = static_cast<unsigned char>(size);
-  }
-
-  constexpr auto size() const -> size_t { return size_; }
-  constexpr auto data() const -> const Char* { return data_; }
-
-  FMT_CONSTEXPR auto operator[](size_t index) -> Char& { return data_[index]; }
-  FMT_CONSTEXPR auto operator[](size_t index) const -> const Char& {
-    return data_[index];
-  }
-};
-}  // namespace detail
-
-enum class presentation_type : unsigned char {
-  none,
-  dec,             // 'd'
-  oct,             // 'o'
-  hex_lower,       // 'x'
-  hex_upper,       // 'X'
-  bin_lower,       // 'b'
-  bin_upper,       // 'B'
-  hexfloat_lower,  // 'a'
-  hexfloat_upper,  // 'A'
-  exp_lower,       // 'e'
-  exp_upper,       // 'E'
-  fixed_lower,     // 'f'
-  fixed_upper,     // 'F'
-  general_lower,   // 'g'
-  general_upper,   // 'G'
-  chr,             // 'c'
-  string,          // 's'
-  pointer,         // 'p'
-  debug            // '?'
+// DEPRECATED! These are kept for ABI compatibility.
+// It is a separate type rather than an alias to make symbols readable.
+struct format_args : basic_format_args<format_context> {
+  template <typename... Args>
+  FMT_INLINE format_args(const Args&... args) : basic_format_args(args...) {}
 };
-
-// Format specifiers for built-in and string types.
-template <typename Char = char> struct format_specs {
-  int width;
-  int precision;
-  presentation_type type;
-  align_t align : 4;
-  sign_t sign : 3;
-  bool alt : 1;  // Alternate form ('#').
-  bool localized : 1;
-  detail::fill_t<Char> fill;
-
-  constexpr format_specs()
-      : width(0),
-        precision(-1),
-        type(presentation_type::none),
-        align(align::none),
-        sign(sign::none),
-        alt(false),
-        localized(false) {}
+struct wformat_args : basic_format_args<wformat_context> {
+  using basic_format_args::basic_format_args;
 };
+#endif
 
 namespace detail {
 
-enum class arg_id_kind { none, index, name };
-
-// An argument reference.
-template <typename Char> struct arg_ref {
-  FMT_CONSTEXPR arg_ref() : kind(arg_id_kind::none), val() {}
-
-  FMT_CONSTEXPR explicit arg_ref(int index)
-      : kind(arg_id_kind::index), val(index) {}
-  FMT_CONSTEXPR explicit arg_ref(basic_string_view<Char> name)
-      : kind(arg_id_kind::name), val(name) {}
-
-  FMT_CONSTEXPR auto operator=(int idx) -> arg_ref& {
-    kind = arg_id_kind::index;
-    val.index = idx;
-    return *this;
-  }
-
-  arg_id_kind kind;
-  union value {
-    FMT_CONSTEXPR value(int idx = 0) : index(idx) {}
-    FMT_CONSTEXPR value(basic_string_view<Char> n) : name(n) {}
-
-    int index;
-    basic_string_view<Char> name;
-  } val;
-};
-
-// Format specifiers with width and precision resolved at formatting rather
-// than parsing time to allow reusing the same parsed specifiers with
-// different sets of arguments (precompilation of format strings).
-template <typename Char = char>
-struct dynamic_format_specs : format_specs<Char> {
-  arg_ref<Char> width_ref;
-  arg_ref<Char> precision_ref;
-};
-
-// Converts a character to ASCII. Returns '\0' on conversion failure.
-template <typename Char, FMT_ENABLE_IF(std::is_integral<Char>::value)>
-constexpr auto to_ascii(Char c) -> char {
-  return c <= 0xff ? static_cast<char>(c) : '\0';
-}
-template <typename Char, FMT_ENABLE_IF(std::is_enum<Char>::value)>
-constexpr auto to_ascii(Char c) -> char {
-  return c <= 0xff ? static_cast<char>(c) : '\0';
-}
-
-// Returns the number of code units in a code point or 1 on error.
-template <typename Char>
-FMT_CONSTEXPR auto code_point_length(const Char* begin) -> int {
-  if (const_check(sizeof(Char) != 1)) return 1;
-  auto c = static_cast<unsigned char>(*begin);
-  return static_cast<int>((0x3a55000000000000ull >> (2 * (c >> 3))) & 0x3) + 1;
-}
-
-// Return the result via the out param to workaround gcc bug 77539.
-template <bool IS_CONSTEXPR, typename T, typename Ptr = const T*>
-FMT_CONSTEXPR auto find(Ptr first, Ptr last, T value, Ptr& out) -> bool {
-  for (out = first; out != last; ++out) {
-    if (*out == value) return true;
-  }
-  return false;
-}
-
-template <>
-inline auto find<false, char>(const char* first, const char* last, char value,
-                              const char*& out) -> bool {
-  out = static_cast<const char*>(
-      std::memchr(first, value, to_unsigned(last - first)));
-  return out != nullptr;
-}
-
-// Parses the range [begin, end) as an unsigned integer. This function assumes
-// that the range is non-empty and the first character is a digit.
-template <typename Char>
-FMT_CONSTEXPR auto parse_nonnegative_int(const Char*& begin, const Char* end,
-                                         int error_value) noexcept -> int {
-  FMT_ASSERT(begin != end && '0' <= *begin && *begin <= '9', "");
-  unsigned value = 0, prev = 0;
-  auto p = begin;
-  do {
-    prev = value;
-    value = value * 10 + unsigned(*p - '0');
-    ++p;
-  } while (p != end && '0' <= *p && *p <= '9');
-  auto num_digits = p - begin;
-  begin = p;
-  if (num_digits <= std::numeric_limits<int>::digits10)
-    return static_cast<int>(value);
-  // Check for overflow.
-  const unsigned max = to_unsigned((std::numeric_limits<int>::max)());
-  return num_digits == std::numeric_limits<int>::digits10 + 1 &&
-                 prev * 10ull + unsigned(p[-1] - '0') <= max
-             ? static_cast<int>(value)
-             : error_value;
-}
-
-FMT_CONSTEXPR inline auto parse_align(char c) -> align_t {
-  switch (c) {
-  case '<':
-    return align::left;
-  case '>':
-    return align::right;
-  case '^':
-    return align::center;
-  }
-  return align::none;
-}
-
-template <typename Char> constexpr auto is_name_start(Char c) -> bool {
-  return ('a' <= c && c <= 'z') || ('A' <= c && c <= 'Z') || c == '_';
-}
-
-template <typename Char, typename Handler>
-FMT_CONSTEXPR auto do_parse_arg_id(const Char* begin, const Char* end,
-                                   Handler&& handler) -> const Char* {
-  Char c = *begin;
-  if (c >= '0' && c <= '9') {
-    int index = 0;
-    constexpr int max = (std::numeric_limits<int>::max)();
-    if (c != '0')
-      index = parse_nonnegative_int(begin, end, max);
-    else
-      ++begin;
-    if (begin == end || (*begin != '}' && *begin != ':'))
-      throw_format_error("invalid format string");
-    else
-      handler.on_index(index);
-    return begin;
-  }
-  if (!is_name_start(c)) {
-    throw_format_error("invalid format string");
-    return begin;
-  }
-  auto it = begin;
-  do {
-    ++it;
-  } while (it != end && (is_name_start(*it) || ('0' <= *it && *it <= '9')));
-  handler.on_name({begin, to_unsigned(it - begin)});
-  return it;
-}
-
-template <typename Char, typename Handler>
-FMT_CONSTEXPR FMT_INLINE auto parse_arg_id(const Char* begin, const Char* end,
-                                           Handler&& handler) -> const Char* {
-  FMT_ASSERT(begin != end, "");
-  Char c = *begin;
-  if (c != '}' && c != ':') return do_parse_arg_id(begin, end, handler);
-  handler.on_auto();
-  return begin;
-}
-
-template <typename Char> struct dynamic_spec_id_handler {
-  basic_format_parse_context<Char>& ctx;
-  arg_ref<Char>& ref;
-
-  FMT_CONSTEXPR void on_auto() {
-    int id = ctx.next_arg_id();
-    ref = arg_ref<Char>(id);
-    ctx.check_dynamic_spec(id);
-  }
-  FMT_CONSTEXPR void on_index(int id) {
-    ref = arg_ref<Char>(id);
-    ctx.check_arg_id(id);
-    ctx.check_dynamic_spec(id);
-  }
-  FMT_CONSTEXPR void on_name(basic_string_view<Char> id) {
-    ref = arg_ref<Char>(id);
-    ctx.check_arg_id(id);
-  }
-};
-
-// Parses [integer | "{" [arg_id] "}"].
-template <typename Char>
-FMT_CONSTEXPR auto parse_dynamic_spec(const Char* begin, const Char* end,
-                                      int& value, arg_ref<Char>& ref,
-                                      basic_format_parse_context<Char>& ctx)
-    -> const Char* {
-  FMT_ASSERT(begin != end, "");
-  if ('0' <= *begin && *begin <= '9') {
-    int val = parse_nonnegative_int(begin, end, -1);
-    if (val != -1)
-      value = val;
-    else
-      throw_format_error("number is too big");
-  } else if (*begin == '{') {
-    ++begin;
-    auto handler = dynamic_spec_id_handler<Char>{ctx, ref};
-    if (begin != end) begin = parse_arg_id(begin, end, handler);
-    if (begin != end && *begin == '}') return ++begin;
-    throw_format_error("invalid format string");
-  }
-  return begin;
-}
-
-template <typename Char>
-FMT_CONSTEXPR auto parse_precision(const Char* begin, const Char* end,
-                                   int& value, arg_ref<Char>& ref,
-                                   basic_format_parse_context<Char>& ctx)
-    -> const Char* {
-  ++begin;
-  if (begin == end || *begin == '}') {
-    throw_format_error("invalid precision");
-    return begin;
-  }
-  return parse_dynamic_spec(begin, end, value, ref, ctx);
-}
-
-enum class state { start, align, sign, hash, zero, width, precision, locale };
-
-// Parses standard format specifiers.
-template <typename Char>
-FMT_CONSTEXPR FMT_INLINE auto parse_format_specs(
-    const Char* begin, const Char* end, dynamic_format_specs<Char>& specs,
-    basic_format_parse_context<Char>& ctx, type arg_type) -> const Char* {
-  auto c = '\0';
-  if (end - begin > 1) {
-    auto next = to_ascii(begin[1]);
-    c = parse_align(next) == align::none ? to_ascii(*begin) : '\0';
-  } else {
-    if (begin == end) return begin;
-    c = to_ascii(*begin);
-  }
-
-  struct {
-    state current_state = state::start;
-    FMT_CONSTEXPR void operator()(state s, bool valid = true) {
-      if (current_state >= s || !valid)
-        throw_format_error("invalid format specifier");
-      current_state = s;
-    }
-  } enter_state;
-
-  using pres = presentation_type;
-  constexpr auto integral_set = sint_set | uint_set | bool_set | char_set;
-  struct {
-    const Char*& begin;
-    dynamic_format_specs<Char>& specs;
-    type arg_type;
-
-    FMT_CONSTEXPR auto operator()(pres pres_type, int set) -> const Char* {
-      if (!in(arg_type, set)) {
-        if (arg_type == type::none_type) return begin;
-        throw_format_error("invalid format specifier");
-      }
-      specs.type = pres_type;
-      return begin + 1;
-    }
-  } parse_presentation_type{begin, specs, arg_type};
-
-  for (;;) {
-    switch (c) {
-    case '<':
-    case '>':
-    case '^':
-      enter_state(state::align);
-      specs.align = parse_align(c);
-      ++begin;
-      break;
-    case '+':
-    case '-':
-    case ' ':
-      if (arg_type == type::none_type) return begin;
-      enter_state(state::sign, in(arg_type, sint_set | float_set));
-      switch (c) {
-      case '+':
-        specs.sign = sign::plus;
-        break;
-      case '-':
-        specs.sign = sign::minus;
-        break;
-      case ' ':
-        specs.sign = sign::space;
-        break;
-      }
-      ++begin;
-      break;
-    case '#':
-      if (arg_type == type::none_type) return begin;
-      enter_state(state::hash, is_arithmetic_type(arg_type));
-      specs.alt = true;
-      ++begin;
-      break;
-    case '0':
-      enter_state(state::zero);
-      if (!is_arithmetic_type(arg_type)) {
-        if (arg_type == type::none_type) return begin;
-        throw_format_error("format specifier requires numeric argument");
-      }
-      if (specs.align == align::none) {
-        // Ignore 0 if align is specified for compatibility with std::format.
-        specs.align = align::numeric;
-        specs.fill[0] = Char('0');
-      }
-      ++begin;
-      break;
-    case '1':
-    case '2':
-    case '3':
-    case '4':
-    case '5':
-    case '6':
-    case '7':
-    case '8':
-    case '9':
-    case '{':
-      enter_state(state::width);
-      begin = parse_dynamic_spec(begin, end, specs.width, specs.width_ref, ctx);
-      break;
-    case '.':
-      if (arg_type == type::none_type) return begin;
-      enter_state(state::precision,
-                  in(arg_type, float_set | string_set | cstring_set));
-      begin = parse_precision(begin, end, specs.precision, specs.precision_ref,
-                              ctx);
-      break;
-    case 'L':
-      if (arg_type == type::none_type) return begin;
-      enter_state(state::locale, is_arithmetic_type(arg_type));
-      specs.localized = true;
-      ++begin;
-      break;
-    case 'd':
-      return parse_presentation_type(pres::dec, integral_set);
-    case 'o':
-      return parse_presentation_type(pres::oct, integral_set);
-    case 'x':
-      return parse_presentation_type(pres::hex_lower, integral_set);
-    case 'X':
-      return parse_presentation_type(pres::hex_upper, integral_set);
-    case 'b':
-      return parse_presentation_type(pres::bin_lower, integral_set);
-    case 'B':
-      return parse_presentation_type(pres::bin_upper, integral_set);
-    case 'a':
-      return parse_presentation_type(pres::hexfloat_lower, float_set);
-    case 'A':
-      return parse_presentation_type(pres::hexfloat_upper, float_set);
-    case 'e':
-      return parse_presentation_type(pres::exp_lower, float_set);
-    case 'E':
-      return parse_presentation_type(pres::exp_upper, float_set);
-    case 'f':
-      return parse_presentation_type(pres::fixed_lower, float_set);
-    case 'F':
-      return parse_presentation_type(pres::fixed_upper, float_set);
-    case 'g':
-      return parse_presentation_type(pres::general_lower, float_set);
-    case 'G':
-      return parse_presentation_type(pres::general_upper, float_set);
-    case 'c':
-      return parse_presentation_type(pres::chr, integral_set);
-    case 's':
-      return parse_presentation_type(pres::string,
-                                     bool_set | string_set | cstring_set);
-    case 'p':
-      return parse_presentation_type(pres::pointer, pointer_set | cstring_set);
-    case '?':
-      return parse_presentation_type(pres::debug,
-                                     char_set | string_set | cstring_set);
-    case '}':
-      return begin;
-    default: {
-      if (*begin == '}') return begin;
-      // Parse fill and alignment.
-      auto fill_end = begin + code_point_length(begin);
-      if (end - fill_end <= 0) {
-        throw_format_error("invalid format specifier");
-        return begin;
-      }
-      if (*begin == '{') {
-        throw_format_error("invalid fill character '{'");
-        return begin;
-      }
-      auto align = parse_align(to_ascii(*fill_end));
-      enter_state(state::align, align != align::none);
-      specs.fill = {begin, to_unsigned(fill_end - begin)};
-      specs.align = align;
-      begin = fill_end + 1;
-    }
-    }
-    if (begin == end) return begin;
-    c = to_ascii(*begin);
-  }
-}
-
-template <typename Char, typename Handler>
-FMT_CONSTEXPR auto parse_replacement_field(const Char* begin, const Char* end,
-                                           Handler&& handler) -> const Char* {
-  struct id_adapter {
-    Handler& handler;
-    int arg_id;
-
-    FMT_CONSTEXPR void on_auto() { arg_id = handler.on_arg_id(); }
-    FMT_CONSTEXPR void on_index(int id) { arg_id = handler.on_arg_id(id); }
-    FMT_CONSTEXPR void on_name(basic_string_view<Char> id) {
-      arg_id = handler.on_arg_id(id);
-    }
-  };
-
-  ++begin;
-  if (begin == end) return handler.on_error("invalid format string"), end;
-  if (*begin == '}') {
-    handler.on_replacement_field(handler.on_arg_id(), begin);
-  } else if (*begin == '{') {
-    handler.on_text(begin, begin + 1);
-  } else {
-    auto adapter = id_adapter{handler, 0};
-    begin = parse_arg_id(begin, end, adapter);
-    Char c = begin != end ? *begin : Char();
-    if (c == '}') {
-      handler.on_replacement_field(adapter.arg_id, begin);
-    } else if (c == ':') {
-      begin = handler.on_format_specs(adapter.arg_id, begin + 1, end);
-      if (begin == end || *begin != '}')
-        return handler.on_error("unknown format specifier"), end;
-    } else {
-      return handler.on_error("missing '}' in format string"), end;
-    }
-  }
-  return begin + 1;
-}
-
-template <bool IS_CONSTEXPR, typename Char, typename Handler>
-FMT_CONSTEXPR FMT_INLINE void parse_format_string(
-    basic_string_view<Char> format_str, Handler&& handler) {
-  auto begin = format_str.data();
-  auto end = begin + format_str.size();
-  if (end - begin < 32) {
-    // Use a simple loop instead of memchr for small strings.
-    const Char* p = begin;
-    while (p != end) {
-      auto c = *p++;
-      if (c == '{') {
-        handler.on_text(begin, p - 1);
-        begin = p = parse_replacement_field(p - 1, end, handler);
-      } else if (c == '}') {
-        if (p == end || *p != '}')
-          return handler.on_error("unmatched '}' in format string");
-        handler.on_text(begin, p);
-        begin = ++p;
-      }
-    }
-    handler.on_text(begin, end);
-    return;
-  }
-  struct writer {
-    FMT_CONSTEXPR void operator()(const Char* from, const Char* to) {
-      if (from == to) return;
-      for (;;) {
-        const Char* p = nullptr;
-        if (!find<IS_CONSTEXPR>(from, to, Char('}'), p))
-          return handler_.on_text(from, to);
-        ++p;
-        if (p == to || *p != '}')
-          return handler_.on_error("unmatched '}' in format string");
-        handler_.on_text(from, p);
-        from = p + 1;
-      }
-    }
-    Handler& handler_;
-  } write = {handler};
-  while (begin != end) {
-    // Doing two passes with memchr (one for '{' and another for '}') is up to
-    // 2.5x faster than the naive one-pass implementation on big format strings.
-    const Char* p = begin;
-    if (*begin != '{' && !find<IS_CONSTEXPR>(begin + 1, end, Char('{'), p))
-      return write(begin, end);
-    write(begin, p);
-    begin = parse_replacement_field(p, end, handler);
-  }
-}
+template <typename Char, FMT_ENABLE_IF(!std::is_same<Char, char>::value)>
+std::basic_string<Char> vformat(
+    basic_string_view<Char> format_str,
+    basic_format_args<buffer_context<type_identity_t<Char>>> args);
 
-template <typename T, bool = is_named_arg<T>::value> struct strip_named_arg {
-  using type = T;
-};
-template <typename T> struct strip_named_arg<T, true> {
-  using type = remove_cvref_t<decltype(T::value)>;
-};
+FMT_API std::string vformat(string_view format_str, format_args args);
 
-template <typename T, typename ParseContext>
-FMT_CONSTEXPR auto parse_format_specs(ParseContext& ctx)
-    -> decltype(ctx.begin()) {
-  using char_type = typename ParseContext::char_type;
-  using context = buffer_context<char_type>;
-  using mapped_type = conditional_t<
-      mapped_type_constant<T, context>::value != type::custom_type,
-      decltype(arg_mapper<context>().map(std::declval<const T&>())),
-      typename strip_named_arg<T>::type>;
-#if defined(__cpp_if_constexpr)
-  if constexpr (std::is_default_constructible<
-                    formatter<mapped_type, char_type>>::value) {
-    return formatter<mapped_type, char_type>().parse(ctx);
-  } else {
-    type_is_unformattable_for<T, char_type> _;
-    return ctx.begin();
-  }
-#else
-  return formatter<mapped_type, char_type>().parse(ctx);
-#endif
-}
-
-// Checks char specs and returns true iff the presentation type is char-like.
 template <typename Char>
-FMT_CONSTEXPR auto check_char_specs(const format_specs<Char>& specs) -> bool {
-  if (specs.type != presentation_type::none &&
-      specs.type != presentation_type::chr &&
-      specs.type != presentation_type::debug) {
-    return false;
-  }
-  if (specs.align == align::numeric || specs.sign != sign::none || specs.alt)
-    throw_format_error("invalid format specifier for char");
-  return true;
-}
-
-#if FMT_USE_NONTYPE_TEMPLATE_ARGS
-template <int N, typename T, typename... Args, typename Char>
-constexpr auto get_arg_index_by_name(basic_string_view<Char> name) -> int {
-  if constexpr (is_statically_named_arg<T>()) {
-    if (name == T::name) return N;
-  }
-  if constexpr (sizeof...(Args) > 0)
-    return get_arg_index_by_name<N + 1, Args...>(name);
-  (void)name;  // Workaround an MSVC bug about "unused" parameter.
-  return -1;
-}
-#endif
-
-template <typename... Args, typename Char>
-FMT_CONSTEXPR auto get_arg_index_by_name(basic_string_view<Char> name) -> int {
-#if FMT_USE_NONTYPE_TEMPLATE_ARGS
-  if constexpr (sizeof...(Args) > 0)
-    return get_arg_index_by_name<0, Args...>(name);
-#endif
-  (void)name;
-  return -1;
-}
-
-template <typename Char, typename... Args> class format_string_checker {
- private:
-  using parse_context_type = compile_parse_context<Char>;
-  static constexpr int num_args = sizeof...(Args);
-
-  // Format specifier parsing function.
-  // In the future basic_format_parse_context will replace compile_parse_context
-  // here and will use is_constant_evaluated and downcasting to access the data
-  // needed for compile-time checks: https://godbolt.org/z/GvWzcTjh1.
-  using parse_func = const Char* (*)(parse_context_type&);
-
-  type types_[num_args > 0 ? static_cast<size_t>(num_args) : 1];
-  parse_context_type context_;
-  parse_func parse_funcs_[num_args > 0 ? static_cast<size_t>(num_args) : 1];
-
- public:
-  explicit FMT_CONSTEXPR format_string_checker(basic_string_view<Char> fmt)
-      : types_{mapped_type_constant<Args, buffer_context<Char>>::value...},
-        context_(fmt, num_args, types_),
-        parse_funcs_{&parse_format_specs<Args, parse_context_type>...} {}
-
-  FMT_CONSTEXPR void on_text(const Char*, const Char*) {}
-
-  FMT_CONSTEXPR auto on_arg_id() -> int { return context_.next_arg_id(); }
-  FMT_CONSTEXPR auto on_arg_id(int id) -> int {
-    return context_.check_arg_id(id), id;
-  }
-  FMT_CONSTEXPR auto on_arg_id(basic_string_view<Char> id) -> int {
-#if FMT_USE_NONTYPE_TEMPLATE_ARGS
-    auto index = get_arg_index_by_name<Args...>(id);
-    if (index < 0) on_error("named argument is not found");
-    return index;
-#else
-    (void)id;
-    on_error("compile-time checks for named arguments require C++20 support");
-    return 0;
-#endif
-  }
-
-  FMT_CONSTEXPR void on_replacement_field(int id, const Char* begin) {
-    on_format_specs(id, begin, begin);  // Call parse() on empty specs.
-  }
-
-  FMT_CONSTEXPR auto on_format_specs(int id, const Char* begin, const Char*)
-      -> const Char* {
-    context_.advance_to(begin);
-    // id >= 0 check is a workaround for gcc 10 bug (#2065).
-    return id >= 0 && id < num_args ? parse_funcs_[id](context_) : begin;
-  }
-
-  FMT_CONSTEXPR void on_error(const char* message) {
-    throw_format_error(message);
-  }
-};
-
-// Reports a compile-time error if S is not a valid format string.
-template <typename..., typename S, FMT_ENABLE_IF(!is_compile_string<S>::value)>
-FMT_INLINE void check_format_string(const S&) {
-#ifdef FMT_ENFORCE_COMPILE_STRING
-  static_assert(is_compile_string<S>::value,
-                "FMT_ENFORCE_COMPILE_STRING requires all format strings to use "
-                "FMT_STRING.");
-#endif
-}
-template <typename... Args, typename S,
-          FMT_ENABLE_IF(is_compile_string<S>::value)>
-void check_format_string(S format_str) {
-  using char_t = typename S::char_type;
-  FMT_CONSTEXPR auto s = basic_string_view<char_t>(format_str);
-  using checker = format_string_checker<char_t, remove_cvref_t<Args>...>;
-  FMT_CONSTEXPR bool error = (parse_format_string<true>(s, checker(s)), true);
-  ignore_unused(error);
-}
+void vformat_to(
+    buffer<Char>& buf, basic_string_view<Char> format_str,
+    basic_format_args<FMT_BUFFER_CONTEXT(type_identity_t<Char>)> args,
+    detail::locale_ref loc = {});
 
-template <typename Char = char> struct vformat_args {
-  using type = basic_format_args<
-      basic_format_context<std::back_insert_iterator<buffer<Char>>, Char>>;
-};
-template <> struct vformat_args<char> {
-  using type = format_args;
-};
-
-// Use vformat_args and avoid type_identity to keep symbols short.
-template <typename Char>
-void vformat_to(buffer<Char>& buf, basic_string_view<Char> fmt,
-                typename vformat_args<Char>::type args, locale_ref loc = {});
+template <typename Char, typename Args,
+          FMT_ENABLE_IF(!std::is_same<Char, char>::value)>
+inline void vprint_mojibake(std::FILE*, basic_string_view<Char>, const Args&) {}
 
 FMT_API void vprint_mojibake(std::FILE*, string_view, format_args);
 #ifndef _WIN32
@@ -2699,140 +1972,37 @@ inline void vprint_mojibake(std::FILE*, string_view, format_args) {}
 #endif
 }  // namespace detail
 
-FMT_BEGIN_EXPORT
-
-// A formatter specialization for natively supported types.
-template <typename T, typename Char>
-struct formatter<T, Char,
-                 enable_if_t<detail::type_constant<T, Char>::value !=
-                             detail::type::custom_type>> {
- private:
-  detail::dynamic_format_specs<Char> specs_;
-
- public:
-  template <typename ParseContext>
-  FMT_CONSTEXPR auto parse(ParseContext& ctx) -> const Char* {
-    auto type = detail::type_constant<T, Char>::value;
-    auto end =
-        detail::parse_format_specs(ctx.begin(), ctx.end(), specs_, ctx, type);
-    if (type == detail::type::char_type) detail::check_char_specs(specs_);
-    return end;
-  }
-
-  template <detail::type U = detail::type_constant<T, Char>::value,
-            FMT_ENABLE_IF(U == detail::type::string_type ||
-                          U == detail::type::cstring_type ||
-                          U == detail::type::char_type)>
-  FMT_CONSTEXPR void set_debug_format(bool set = true) {
-    specs_.type = set ? presentation_type::debug : presentation_type::none;
-  }
-
-  template <typename FormatContext>
-  FMT_CONSTEXPR auto format(const T& val, FormatContext& ctx) const
-      -> decltype(ctx.out());
-};
-
-template <typename Char = char> struct runtime_format_string {
-  basic_string_view<Char> str;
-};
-
-/** A compile-time format string. */
-template <typename Char, typename... Args> class basic_format_string {
- private:
-  basic_string_view<Char> str_;
-
- public:
-  template <typename S,
-            FMT_ENABLE_IF(
-                std::is_convertible<const S&, basic_string_view<Char>>::value)>
-  FMT_CONSTEVAL FMT_INLINE basic_format_string(const S& s) : str_(s) {
-    static_assert(
-        detail::count<
-            (std::is_base_of<detail::view, remove_reference_t<Args>>::value &&
-             std::is_reference<Args>::value)...>() == 0,
-        "passing views as lvalues is disallowed");
-#ifdef FMT_HAS_CONSTEVAL
-    if constexpr (detail::count_named_args<Args...>() ==
-                  detail::count_statically_named_args<Args...>()) {
-      using checker =
-          detail::format_string_checker<Char, remove_cvref_t<Args>...>;
-      detail::parse_format_string<true>(str_, checker(s));
-    }
-#else
-    detail::check_format_string<Args...>(s);
-#endif
-  }
-  basic_format_string(runtime_format_string<Char> fmt) : str_(fmt.str) {}
-
-  FMT_INLINE operator basic_string_view<Char>() const { return str_; }
-  FMT_INLINE auto get() const -> basic_string_view<Char> { return str_; }
-};
-
-#if FMT_GCC_VERSION && FMT_GCC_VERSION < 409
-// Workaround broken conversion on older gcc.
-template <typename...> using format_string = string_view;
-inline auto runtime(string_view s) -> string_view { return s; }
-#else
-template <typename... Args>
-using format_string = basic_format_string<char, type_identity_t<Args>...>;
-/**
-  \rst
-  Creates a runtime format string.
-
-  **Example**::
-
-    // Check format string at runtime instead of compile-time.
-    fmt::print(fmt::runtime("{:d}"), "I am not a number");
-  \endrst
- */
-inline auto runtime(string_view s) -> runtime_format_string<> { return {{s}}; }
-#endif
-
-FMT_API auto vformat(string_view fmt, format_args args) -> std::string;
-
-/**
-  \rst
-  Formats ``args`` according to specifications in ``fmt`` and returns the result
-  as a string.
-
-  **Example**::
-
-    #include <fmt/core.h>
-    std::string message = fmt::format("The answer is {}.", 42);
-  \endrst
-*/
-template <typename... T>
-FMT_NODISCARD FMT_INLINE auto format(format_string<T...> fmt, T&&... args)
-    -> std::string {
-  return vformat(fmt, fmt::make_format_args(args...));
-}
-
 /** Formats a string and writes the output to ``out``. */
-template <typename OutputIt,
-          FMT_ENABLE_IF(detail::is_output_iterator<OutputIt, char>::value)>
-auto vformat_to(OutputIt out, string_view fmt, format_args args) -> OutputIt {
-  auto&& buf = detail::get_buffer<char>(out);
-  detail::vformat_to(buf, fmt, args, {});
-  return detail::get_iterator(buf, out);
+// GCC 8 and earlier cannot handle std::back_insert_iterator<Container> with
+// vformat_to<ArgFormatter>(...) overload, so SFINAE on iterator type instead.
+template <typename OutputIt, typename S, typename Char = char_t<S>,
+          bool enable = detail::is_output_iterator<OutputIt, Char>::value>
+auto vformat_to(OutputIt out, const S& format_str,
+                basic_format_args<buffer_context<type_identity_t<Char>>> args)
+    -> typename std::enable_if<enable, OutputIt>::type {
+  decltype(detail::get_buffer<Char>(out)) buf(detail::get_buffer_init(out));
+  detail::vformat_to(buf, to_string_view(format_str), args);
+  return detail::get_iterator(buf);
 }
 
 /**
  \rst
- Formats ``args`` according to specifications in ``fmt``, writes the result to
- the output iterator ``out`` and returns the iterator past the end of the output
- range. `format_to` does not append a terminating null character.
+ Formats arguments, writes the result to the output iterator ``out`` and returns
+ the iterator past the end of the output range.
 
  **Example**::
 
-   auto out = std::vector<char>();
+   std::vector<char> out;
    fmt::format_to(std::back_inserter(out), "{}", 42);
  \endrst
  */
-template <typename OutputIt, typename... T,
-          FMT_ENABLE_IF(detail::is_output_iterator<OutputIt, char>::value)>
-FMT_INLINE auto format_to(OutputIt out, format_string<T...> fmt, T&&... args)
-    -> OutputIt {
-  return vformat_to(out, fmt, fmt::make_format_args(args...));
+// We cannot use FMT_ENABLE_IF because of a bug in gcc 8.3.
+template <typename OutputIt, typename S, typename... Args,
+          bool enable = detail::is_output_iterator<OutputIt, char_t<S>>::value>
+inline auto format_to(OutputIt out, const S& format_str, Args&&... args) ->
+    typename std::enable_if<enable, OutputIt>::type {
+  const auto& vargs = fmt::make_args_checked<Args...>(format_str, args...);
+  return vformat_to(out, to_string_view(format_str), vargs);
 }
 
 template <typename OutputIt> struct format_to_n_result {
@@ -2842,100 +2012,111 @@ template <typename OutputIt> struct format_to_n_result {
   size_t size;
 };
 
-template <typename OutputIt, typename... T,
-          FMT_ENABLE_IF(detail::is_output_iterator<OutputIt, char>::value)>
-auto vformat_to_n(OutputIt out, size_t n, string_view fmt, format_args args)
-    -> format_to_n_result<OutputIt> {
-  using traits = detail::fixed_buffer_traits;
-  auto buf = detail::iterator_buffer<OutputIt, char, traits>(out, n);
-  detail::vformat_to(buf, fmt, args, {});
+template <typename OutputIt, typename Char, typename... Args,
+          FMT_ENABLE_IF(detail::is_output_iterator<OutputIt, Char>::value)>
+inline format_to_n_result<OutputIt> vformat_to_n(
+    OutputIt out, size_t n, basic_string_view<Char> format_str,
+    basic_format_args<buffer_context<type_identity_t<Char>>> args) {
+  detail::iterator_buffer<OutputIt, Char, detail::fixed_buffer_traits> buf(out,
+                                                                           n);
+  detail::vformat_to(buf, format_str, args);
   return {buf.out(), buf.count()};
 }
 
 /**
-  \rst
-  Formats ``args`` according to specifications in ``fmt``, writes up to ``n``
-  characters of the result to the output iterator ``out`` and returns the total
-  (not truncated) output size and the iterator past the end of the output range.
-  `format_to_n` does not append a terminating null character.
-  \endrst
+ \rst
+ Formats arguments, writes up to ``n`` characters of the result to the output
+ iterator ``out`` and returns the total output size and the iterator past the
+ end of the output range.
+ \endrst
  */
-template <typename OutputIt, typename... T,
-          FMT_ENABLE_IF(detail::is_output_iterator<OutputIt, char>::value)>
-FMT_INLINE auto format_to_n(OutputIt out, size_t n, format_string<T...> fmt,
-                            T&&... args) -> format_to_n_result<OutputIt> {
-  return vformat_to_n(out, n, fmt, fmt::make_format_args(args...));
+template <typename OutputIt, typename S, typename... Args,
+          bool enable = detail::is_output_iterator<OutputIt, char_t<S>>::value>
+inline auto format_to_n(OutputIt out, size_t n, const S& format_str,
+                        const Args&... args) ->
+    typename std::enable_if<enable, format_to_n_result<OutputIt>>::type {
+  const auto& vargs = fmt::make_args_checked<Args...>(format_str, args...);
+  return vformat_to_n(out, n, to_string_view(format_str), vargs);
 }
 
-/** Returns the number of chars in the output of ``format(fmt, args...)``. */
-template <typename... T>
-FMT_NODISCARD FMT_INLINE auto formatted_size(format_string<T...> fmt,
-                                             T&&... args) -> size_t {
-  auto buf = detail::counting_buffer<>();
-  detail::vformat_to<char>(buf, fmt, fmt::make_format_args(args...), {});
+/**
+  Returns the number of characters in the output of
+  ``format(format_str, args...)``.
+ */
+template <typename... Args>
+inline size_t formatted_size(string_view format_str, Args&&... args) {
+  const auto& vargs = fmt::make_args_checked<Args...>(format_str, args...);
+  detail::counting_buffer<> buf;
+  detail::vformat_to(buf, format_str, vargs);
   return buf.count();
 }
 
-FMT_API void vprint(string_view fmt, format_args args);
-FMT_API void vprint(std::FILE* f, string_view fmt, format_args args);
+template <typename S, typename Char = char_t<S>>
+FMT_INLINE std::basic_string<Char> vformat(
+    const S& format_str,
+    basic_format_args<buffer_context<type_identity_t<Char>>> args) {
+  return detail::vformat(to_string_view(format_str), args);
+}
 
 /**
   \rst
-  Formats ``args`` according to specifications in ``fmt`` and writes the output
-  to ``stdout``.
+  Formats arguments and returns the result as a string.
 
   **Example**::
 
-    fmt::print("Elapsed time: {0:.2f} seconds", 1.23);
+    #include <fmt-vt/core.h>
+    std::string message = fmt::format("The answer is {}", 42);
   \endrst
- */
-template <typename... T>
-FMT_INLINE void print(format_string<T...> fmt, T&&... args) {
-  const auto& vargs = fmt::make_format_args(args...);
-  return detail::is_utf8() ? vprint(fmt, vargs)
-                           : detail::vprint_mojibake(stdout, fmt, vargs);
+*/
+// Pass char_t as a default template parameter instead of using
+// std::basic_string<char_t<S>> to reduce the symbol size.
+template <typename S, typename... Args, typename Char = char_t<S>>
+FMT_INLINE std::basic_string<Char> format(const S& format_str, Args&&... args) {
+  const auto& vargs = fmt::make_args_checked<Args...>(format_str, args...);
+  return detail::vformat(to_string_view(format_str), vargs);
 }
 
+FMT_API void vprint(string_view, format_args);
+FMT_API void vprint(std::FILE*, string_view, format_args);
+
 /**
   \rst
-  Formats ``args`` according to specifications in ``fmt`` and writes the
-  output to the file ``f``.
+  Formats ``args`` according to specifications in ``format_str`` and writes the
+  output to the file ``f``. Strings are assumed to be Unicode-encoded unless the
+  ``FMT_UNICODE`` macro is set to 0.
 
   **Example**::
 
     fmt::print(stderr, "Don't {}!", "panic");
   \endrst
  */
-template <typename... T>
-FMT_INLINE void print(std::FILE* f, format_string<T...> fmt, T&&... args) {
-  const auto& vargs = fmt::make_format_args(args...);
-  return detail::is_utf8() ? vprint(f, fmt, vargs)
-                           : detail::vprint_mojibake(f, fmt, vargs);
+template <typename S, typename... Args, typename Char = char_t<S>>
+inline void print(std::FILE* f, const S& format_str, Args&&... args) {
+  const auto& vargs = fmt::make_args_checked<Args...>(format_str, args...);
+  return detail::is_unicode<Char>()
+             ? vprint(f, to_string_view(format_str), vargs)
+             : detail::vprint_mojibake(f, to_string_view(format_str), vargs);
 }
 
 /**
-  Formats ``args`` according to specifications in ``fmt`` and writes the
-  output to the file ``f`` followed by a newline.
- */
-template <typename... T>
-FMT_INLINE void println(std::FILE* f, format_string<T...> fmt, T&&... args) {
-  return fmt::print(f, "{}\n", fmt::format(fmt, std::forward<T>(args)...));
-}
+  \rst
+  Formats ``args`` according to specifications in ``format_str`` and writes
+  the output to ``stdout``. Strings are assumed to be Unicode-encoded unless
+  the ``FMT_UNICODE`` macro is set to 0.
 
-/**
-  Formats ``args`` according to specifications in ``fmt`` and writes the output
-  to ``stdout`` followed by a newline.
+  **Example**::
+
+    fmt::print("Elapsed time: {0:.2f} seconds", 1.23);
+  \endrst
  */
-template <typename... T>
-FMT_INLINE void println(format_string<T...> fmt, T&&... args) {
-  return fmt::println(stdout, fmt, std::forward<T>(args)...);
+template <typename S, typename... Args, typename Char = char_t<S>>
+inline void print(const S& format_str, Args&&... args) {
+  const auto& vargs = fmt::make_args_checked<Args...>(format_str, args...);
+  return detail::is_unicode<Char>()
+             ? vprint(to_string_view(format_str), vargs)
+             : detail::vprint_mojibake(stdout, to_string_view(format_str),
+                                       vargs);
 }
-
-FMT_END_EXPORT
-FMT_GCC_PRAGMA("GCC pop_options")
 FMT_END_NAMESPACE
 
-#ifdef FMT_HEADER_ONLY
-#  include "format.h"
-#endif
 #endif  // FMT_CORE_H_
diff --git a/lib/fmt/include/fmt-vt/format-inl.h b/lib/fmt/include/fmt-vt/format-inl.h
index 5f8c83a219..8f2fe7354a 100644
--- a/lib/fmt/include/fmt-vt/format-inl.h
+++ b/lib/fmt/include/fmt-vt/format-inl.h
@@ -8,22 +8,30 @@
 #ifndef FMT_FORMAT_INL_H_
 #define FMT_FORMAT_INL_H_
 
-#include <algorithm>
-#include <cerrno>  // errno
+#include <cassert>
+#include <cctype>
 #include <climits>
 #include <cmath>
+#include <cstdarg>
+#include <cstring>  // std::memmove
+#include <cwchar>
 #include <exception>
 
 #ifndef FMT_STATIC_THOUSANDS_SEPARATOR
 #  include <locale>
 #endif
 
-#if defined(_WIN32) && !defined(FMT_WINDOWS_NO_WCHAR)
+#ifdef _WIN32
 #  include <io.h>  // _isatty
 #endif
 
 #include "format.h"
 
+// Dummy implementations of strerror_r and strerror_s called if corresponding
+// system functions are not available.
+inline fmt::detail::null<> strerror_r(int, char*, ...) { return {}; }
+inline fmt::detail::null<> strerror_s(char*, size_t, ...) { return {}; }
+
 FMT_BEGIN_NAMESPACE
 namespace detail {
 
@@ -36,12 +44,91 @@ FMT_FUNC void assert_fail(const char* file, int line, const char* message) {
   std::terminate();
 }
 
-FMT_FUNC void throw_format_error(const char* message) {
-  FMT_THROW(format_error(message));
+#ifndef _MSC_VER
+#  define FMT_SNPRINTF snprintf
+#else  // _MSC_VER
+inline int fmt_snprintf(char* buffer, size_t size, const char* format, ...) {
+  va_list args;
+  va_start(args, format);
+  int result = vsnprintf_s(buffer, size, _TRUNCATE, format, args);
+  va_end(args);
+  return result;
+}
+#  define FMT_SNPRINTF fmt_snprintf
+#endif  // _MSC_VER
+
+// A portable thread-safe version of strerror.
+// Sets buffer to point to a string describing the error code.
+// This can be either a pointer to a string stored in buffer,
+// or a pointer to some static immutable string.
+// Returns one of the following values:
+//   0      - success
+//   ERANGE - buffer is not large enough to store the error message
+//   other  - failure
+// Buffer should be at least of size 1.
+inline int safe_strerror(int error_code, char*& buffer,
+                         size_t buffer_size) FMT_NOEXCEPT {
+  FMT_ASSERT(buffer != nullptr && buffer_size != 0, "invalid buffer");
+
+  class dispatcher {
+   private:
+    int error_code_;
+    char*& buffer_;
+    size_t buffer_size_;
+
+    // A noop assignment operator to avoid bogus warnings.
+    void operator=(const dispatcher&) {}
+
+    // Handle the result of XSI-compliant version of strerror_r.
+    int handle(int result) {
+      // glibc versions before 2.13 return result in errno.
+      return result == -1 ? errno : result;
+    }
+
+    // Handle the result of GNU-specific version of strerror_r.
+    FMT_MAYBE_UNUSED
+    int handle(char* message) {
+      // If the buffer is full then the message is probably truncated.
+      if (message == buffer_ && strlen(buffer_) == buffer_size_ - 1)
+        return ERANGE;
+      buffer_ = message;
+      return 0;
+    }
+
+    // Handle the case when strerror_r is not available.
+    FMT_MAYBE_UNUSED
+    int handle(detail::null<>) {
+      return fallback(strerror_s(buffer_, buffer_size_, error_code_));
+    }
+
+    // Fallback to strerror_s when strerror_r is not available.
+    FMT_MAYBE_UNUSED
+    int fallback(int result) {
+      // If the buffer is full then the message is probably truncated.
+      return result == 0 && strlen(buffer_) == buffer_size_ - 1 ? ERANGE
+                                                                : result;
+    }
+
+#if !FMT_MSC_VER
+    // Fallback to strerror if strerror_r and strerror_s are not available.
+    int fallback(detail::null<>) {
+      errno = 0;
+      buffer_ = strerror(error_code_);
+      return errno;
+    }
+#endif
+
+   public:
+    dispatcher(int err_code, char*& buf, size_t buf_size)
+        : error_code_(err_code), buffer_(buf), buffer_size_(buf_size) {}
+
+    int run() { return handle(strerror_r(error_code_, buffer_, buffer_size_)); }
+  };
+  return dispatcher(error_code, buffer, buffer_size).run();
 }
 
 FMT_FUNC void format_error_code(detail::buffer<char>& out, int error_code,
-                                string_view message) noexcept {
+                                string_view message) FMT_NOEXCEPT {
   // Report error code making sure that the output fits into
   // inline_buffer_size to avoid dynamic memory allocation and potential
   // bad_alloc.
@@ -58,28 +145,31 @@ FMT_FUNC void format_error_code(detail::buffer<char>& out, int error_code,
   error_code_size += detail::to_unsigned(detail::count_digits(abs_value));
   auto it = buffer_appender<char>(out);
   if (message.size() <= inline_buffer_size - error_code_size)
-    format_to(it, FMT_STRING("{}{}"), message, SEP);
-  format_to(it, FMT_STRING("{}{}"), ERROR_STR, error_code);
-  FMT_ASSERT(out.size() <= inline_buffer_size, "");
+    format_to(it, "{}{}", message, SEP);
+  format_to(it, "{}{}", ERROR_STR, error_code);
+  assert(out.size() <= inline_buffer_size);
 }
 
 FMT_FUNC void report_error(format_func func, int error_code,
-                           const char* message) noexcept {
+                           string_view message) FMT_NOEXCEPT {
   memory_buffer full_message;
   func(full_message, error_code, message);
   // Don't use fwrite_fully because the latter may throw.
-  if (std::fwrite(full_message.data(), full_message.size(), 1, stderr) > 0)
-    std::fputc('\n', stderr);
+  (void)std::fwrite(full_message.data(), full_message.size(), 1, stderr);
+  std::fputc('\n', stderr);
 }
 
 // A wrapper around fwrite that throws on error.
-inline void fwrite_fully(const void* ptr, size_t count, FILE* stream) {
-  size_t written = std::fwrite(ptr, 1, count, stream);
-  if (written < count)
-    FMT_THROW(system_error(errno, FMT_STRING("cannot write to file")));
+inline void fwrite_fully(const void* ptr, size_t size, size_t count,
+                         FILE* stream) {
+  size_t written = std::fwrite(ptr, size, count, stream);
+  if (written < count) FMT_THROW(system_error(errno, "cannot write to file"));
 }
+}  // namespace detail
+
+#if !defined(FMT_STATIC_THOUSANDS_SEPARATOR)
+namespace detail {
 
-#ifndef FMT_STATIC_THOUSANDS_SEPARATOR
 template <typename Locale>
 locale_ref::locale_ref(const Locale& loc) : locale_(&loc) {
   static_assert(std::is_same<Locale, std::locale>::value, "");
@@ -90,252 +180,1698 @@ template <typename Locale> Locale locale_ref::get() const {
   return locale_ ? *static_cast<const std::locale*>(locale_) : std::locale();
 }
 
-template <typename Char>
-FMT_FUNC auto thousands_sep_impl(locale_ref loc) -> thousands_sep_result<Char> {
-  auto& facet = std::use_facet<std::numpunct<Char>>(loc.get<std::locale>());
-  auto grouping = facet.grouping();
-  auto thousands_sep = grouping.empty() ? Char() : facet.thousands_sep();
-  return {std::move(grouping), thousands_sep};
+template <typename Char> FMT_FUNC std::string grouping_impl(locale_ref loc) {
+  return std::use_facet<std::numpunct<Char>>(loc.get<std::locale>()).grouping();
+}
+template <typename Char> FMT_FUNC Char thousands_sep_impl(locale_ref loc) {
+  return std::use_facet<std::numpunct<Char>>(loc.get<std::locale>())
+      .thousands_sep();
 }
 template <typename Char> FMT_FUNC Char decimal_point_impl(locale_ref loc) {
   return std::use_facet<std::numpunct<Char>>(loc.get<std::locale>())
       .decimal_point();
 }
+}  // namespace detail
 #else
 template <typename Char>
-FMT_FUNC auto thousands_sep_impl(locale_ref) -> thousands_sep_result<Char> {
-  return {"\03", FMT_STATIC_THOUSANDS_SEPARATOR};
+FMT_FUNC std::string detail::grouping_impl(locale_ref) {
+  return "\03";
+}
+template <typename Char> FMT_FUNC Char detail::thousands_sep_impl(locale_ref) {
+  return FMT_STATIC_THOUSANDS_SEPARATOR;
 }
-template <typename Char> FMT_FUNC Char decimal_point_impl(locale_ref) {
+template <typename Char> FMT_FUNC Char detail::decimal_point_impl(locale_ref) {
   return '.';
 }
 #endif
 
-FMT_FUNC auto write_loc(appender out, loc_value value,
-                        const format_specs<>& specs, locale_ref loc) -> bool {
-#ifndef FMT_STATIC_THOUSANDS_SEPARATOR
-  auto locale = loc.get<std::locale>();
-  // We cannot use the num_put<char> facet because it may produce output in
-  // a wrong encoding.
-  using facet = format_facet<std::locale>;
-  if (std::has_facet<facet>(locale))
-    return std::use_facet<facet>(locale).put(out, value, specs);
-  return facet(locale).put(out, value, specs);
-#endif
-  return false;
+FMT_API FMT_FUNC format_error::~format_error() FMT_NOEXCEPT = default;
+FMT_API FMT_FUNC system_error::~system_error() FMT_NOEXCEPT = default;
+
+FMT_FUNC void system_error::init(int err_code, string_view format_str,
+                                 format_args args) {
+  error_code_ = err_code;
+  memory_buffer buffer;
+  format_system_error(buffer, err_code, vformat(format_str, args));
+  std::runtime_error& base = *this;
+  base = std::runtime_error(to_string(buffer));
 }
-}  // namespace detail
 
-template <typename Locale> typename Locale::id format_facet<Locale>::id;
+namespace detail {
 
-#ifndef FMT_STATIC_THOUSANDS_SEPARATOR
-template <typename Locale> format_facet<Locale>::format_facet(Locale& loc) {
-  auto& numpunct = std::use_facet<std::numpunct<char>>(loc);
-  grouping_ = numpunct.grouping();
-  if (!grouping_.empty()) separator_ = std::string(1, numpunct.thousands_sep());
+template <> FMT_FUNC int count_digits<4>(detail::fallback_uintptr n) {
+  // fallback_uintptr is always stored in little endian.
+  int i = static_cast<int>(sizeof(void*)) - 1;
+  while (i > 0 && n.value[i] == 0) --i;
+  auto char_digits = std::numeric_limits<unsigned char>::digits / 4;
+  return i >= 0 ? i * char_digits + count_digits<4, unsigned>(n.value[i]) : 1;
 }
 
-template <>
-FMT_API FMT_FUNC auto format_facet<std::locale>::do_put(
-    appender out, loc_value val, const format_specs<>& specs) const -> bool {
-  return val.visit(
-      detail::loc_writer<>{out, specs, separator_, grouping_, decimal_point_});
+template <typename T>
+const typename basic_data<T>::digit_pair basic_data<T>::digits[] = {
+    {'0', '0'}, {'0', '1'}, {'0', '2'}, {'0', '3'}, {'0', '4'}, {'0', '5'},
+    {'0', '6'}, {'0', '7'}, {'0', '8'}, {'0', '9'}, {'1', '0'}, {'1', '1'},
+    {'1', '2'}, {'1', '3'}, {'1', '4'}, {'1', '5'}, {'1', '6'}, {'1', '7'},
+    {'1', '8'}, {'1', '9'}, {'2', '0'}, {'2', '1'}, {'2', '2'}, {'2', '3'},
+    {'2', '4'}, {'2', '5'}, {'2', '6'}, {'2', '7'}, {'2', '8'}, {'2', '9'},
+    {'3', '0'}, {'3', '1'}, {'3', '2'}, {'3', '3'}, {'3', '4'}, {'3', '5'},
+    {'3', '6'}, {'3', '7'}, {'3', '8'}, {'3', '9'}, {'4', '0'}, {'4', '1'},
+    {'4', '2'}, {'4', '3'}, {'4', '4'}, {'4', '5'}, {'4', '6'}, {'4', '7'},
+    {'4', '8'}, {'4', '9'}, {'5', '0'}, {'5', '1'}, {'5', '2'}, {'5', '3'},
+    {'5', '4'}, {'5', '5'}, {'5', '6'}, {'5', '7'}, {'5', '8'}, {'5', '9'},
+    {'6', '0'}, {'6', '1'}, {'6', '2'}, {'6', '3'}, {'6', '4'}, {'6', '5'},
+    {'6', '6'}, {'6', '7'}, {'6', '8'}, {'6', '9'}, {'7', '0'}, {'7', '1'},
+    {'7', '2'}, {'7', '3'}, {'7', '4'}, {'7', '5'}, {'7', '6'}, {'7', '7'},
+    {'7', '8'}, {'7', '9'}, {'8', '0'}, {'8', '1'}, {'8', '2'}, {'8', '3'},
+    {'8', '4'}, {'8', '5'}, {'8', '6'}, {'8', '7'}, {'8', '8'}, {'8', '9'},
+    {'9', '0'}, {'9', '1'}, {'9', '2'}, {'9', '3'}, {'9', '4'}, {'9', '5'},
+    {'9', '6'}, {'9', '7'}, {'9', '8'}, {'9', '9'}};
+
+template <typename T>
+const char basic_data<T>::hex_digits[] = "0123456789abcdef";
+
+#define FMT_POWERS_OF_10(factor)                                             \
+  factor * 10, (factor)*100, (factor)*1000, (factor)*10000, (factor)*100000, \
+      (factor)*1000000, (factor)*10000000, (factor)*100000000,               \
+      (factor)*1000000000
+
+template <typename T>
+const uint64_t basic_data<T>::powers_of_10_64[] = {
+    1, FMT_POWERS_OF_10(1), FMT_POWERS_OF_10(1000000000ULL),
+    10000000000000000000ULL};
+
+template <typename T>
+const uint32_t basic_data<T>::zero_or_powers_of_10_32[] = {0,
+                                                           FMT_POWERS_OF_10(1)};
+template <typename T>
+const uint64_t basic_data<T>::zero_or_powers_of_10_64[] = {
+    0, FMT_POWERS_OF_10(1), FMT_POWERS_OF_10(1000000000ULL),
+    10000000000000000000ULL};
+
+template <typename T>
+const uint32_t basic_data<T>::zero_or_powers_of_10_32_new[] = {
+    0, 0, FMT_POWERS_OF_10(1)};
+
+template <typename T>
+const uint64_t basic_data<T>::zero_or_powers_of_10_64_new[] = {
+    0, 0, FMT_POWERS_OF_10(1), FMT_POWERS_OF_10(1000000000ULL),
+    10000000000000000000ULL};
+
+// Normalized 64-bit significands of pow(10, k), for k = -348, -340, ..., 340.
+// These are generated by support/compute-powers.py.
+template <typename T>
+const uint64_t basic_data<T>::grisu_pow10_significands[] = {
+    0xfa8fd5a0081c0288, 0xbaaee17fa23ebf76, 0x8b16fb203055ac76,
+    0xcf42894a5dce35ea, 0x9a6bb0aa55653b2d, 0xe61acf033d1a45df,
+    0xab70fe17c79ac6ca, 0xff77b1fcbebcdc4f, 0xbe5691ef416bd60c,
+    0x8dd01fad907ffc3c, 0xd3515c2831559a83, 0x9d71ac8fada6c9b5,
+    0xea9c227723ee8bcb, 0xaecc49914078536d, 0x823c12795db6ce57,
+    0xc21094364dfb5637, 0x9096ea6f3848984f, 0xd77485cb25823ac7,
+    0xa086cfcd97bf97f4, 0xef340a98172aace5, 0xb23867fb2a35b28e,
+    0x84c8d4dfd2c63f3b, 0xc5dd44271ad3cdba, 0x936b9fcebb25c996,
+    0xdbac6c247d62a584, 0xa3ab66580d5fdaf6, 0xf3e2f893dec3f126,
+    0xb5b5ada8aaff80b8, 0x87625f056c7c4a8b, 0xc9bcff6034c13053,
+    0x964e858c91ba2655, 0xdff9772470297ebd, 0xa6dfbd9fb8e5b88f,
+    0xf8a95fcf88747d94, 0xb94470938fa89bcf, 0x8a08f0f8bf0f156b,
+    0xcdb02555653131b6, 0x993fe2c6d07b7fac, 0xe45c10c42a2b3b06,
+    0xaa242499697392d3, 0xfd87b5f28300ca0e, 0xbce5086492111aeb,
+    0x8cbccc096f5088cc, 0xd1b71758e219652c, 0x9c40000000000000,
+    0xe8d4a51000000000, 0xad78ebc5ac620000, 0x813f3978f8940984,
+    0xc097ce7bc90715b3, 0x8f7e32ce7bea5c70, 0xd5d238a4abe98068,
+    0x9f4f2726179a2245, 0xed63a231d4c4fb27, 0xb0de65388cc8ada8,
+    0x83c7088e1aab65db, 0xc45d1df942711d9a, 0x924d692ca61be758,
+    0xda01ee641a708dea, 0xa26da3999aef774a, 0xf209787bb47d6b85,
+    0xb454e4a179dd1877, 0x865b86925b9bc5c2, 0xc83553c5c8965d3d,
+    0x952ab45cfa97a0b3, 0xde469fbd99a05fe3, 0xa59bc234db398c25,
+    0xf6c69a72a3989f5c, 0xb7dcbf5354e9bece, 0x88fcf317f22241e2,
+    0xcc20ce9bd35c78a5, 0x98165af37b2153df, 0xe2a0b5dc971f303a,
+    0xa8d9d1535ce3b396, 0xfb9b7cd9a4a7443c, 0xbb764c4ca7a44410,
+    0x8bab8eefb6409c1a, 0xd01fef10a657842c, 0x9b10a4e5e9913129,
+    0xe7109bfba19c0c9d, 0xac2820d9623bf429, 0x80444b5e7aa7cf85,
+    0xbf21e44003acdd2d, 0x8e679c2f5e44ff8f, 0xd433179d9c8cb841,
+    0x9e19db92b4e31ba9, 0xeb96bf6ebadf77d9, 0xaf87023b9bf0ee6b,
+};
+
+// Binary exponents of pow(10, k), for k = -348, -340, ..., 340, corresponding
+// to significands above.
+template <typename T>
+const int16_t basic_data<T>::grisu_pow10_exponents[] = {
+    -1220, -1193, -1166, -1140, -1113, -1087, -1060, -1034, -1007, -980, -954,
+    -927,  -901,  -874,  -847,  -821,  -794,  -768,  -741,  -715,  -688, -661,
+    -635,  -608,  -582,  -555,  -529,  -502,  -475,  -449,  -422,  -396, -369,
+    -343,  -316,  -289,  -263,  -236,  -210,  -183,  -157,  -130,  -103, -77,
+    -50,   -24,   3,     30,    56,    83,    109,   136,   162,   189,  216,
+    242,   269,   295,   322,   348,   375,   402,   428,   455,   481,  508,
+    534,   561,   588,   614,   641,   667,   694,   720,   747,   774,  800,
+    827,   853,   880,   907,   933,   960,   986,   1013,  1039,  1066};
+
+template <typename T>
+const divtest_table_entry<uint32_t> basic_data<T>::divtest_table_for_pow5_32[] =
+    {{0x00000001, 0xffffffff}, {0xcccccccd, 0x33333333},
+     {0xc28f5c29, 0x0a3d70a3}, {0x26e978d5, 0x020c49ba},
+     {0x3afb7e91, 0x0068db8b}, {0x0bcbe61d, 0x0014f8b5},
+     {0x68c26139, 0x000431bd}, {0xae8d46a5, 0x0000d6bf},
+     {0x22e90e21, 0x00002af3}, {0x3a2e9c6d, 0x00000897},
+     {0x3ed61f49, 0x000001b7}};
+
+template <typename T>
+const divtest_table_entry<uint64_t> basic_data<T>::divtest_table_for_pow5_64[] =
+    {{0x0000000000000001, 0xffffffffffffffff},
+     {0xcccccccccccccccd, 0x3333333333333333},
+     {0x8f5c28f5c28f5c29, 0x0a3d70a3d70a3d70},
+     {0x1cac083126e978d5, 0x020c49ba5e353f7c},
+     {0xd288ce703afb7e91, 0x0068db8bac710cb2},
+     {0x5d4e8fb00bcbe61d, 0x0014f8b588e368f0},
+     {0x790fb65668c26139, 0x000431bde82d7b63},
+     {0xe5032477ae8d46a5, 0x0000d6bf94d5e57a},
+     {0xc767074b22e90e21, 0x00002af31dc46118},
+     {0x8e47ce423a2e9c6d, 0x0000089705f4136b},
+     {0x4fa7f60d3ed61f49, 0x000001b7cdfd9d7b},
+     {0x0fee64690c913975, 0x00000057f5ff85e5},
+     {0x3662e0e1cf503eb1, 0x000000119799812d},
+     {0xa47a2cf9f6433fbd, 0x0000000384b84d09},
+     {0x54186f653140a659, 0x00000000b424dc35},
+     {0x7738164770402145, 0x0000000024075f3d},
+     {0xe4a4d1417cd9a041, 0x000000000734aca5},
+     {0xc75429d9e5c5200d, 0x000000000170ef54},
+     {0xc1773b91fac10669, 0x000000000049c977},
+     {0x26b172506559ce15, 0x00000000000ec1e4},
+     {0xd489e3a9addec2d1, 0x000000000002f394},
+     {0x90e860bb892c8d5d, 0x000000000000971d},
+     {0x502e79bf1b6f4f79, 0x0000000000001e39},
+     {0xdcd618596be30fe5, 0x000000000000060b}};
+
+template <typename T>
+const uint64_t basic_data<T>::dragonbox_pow10_significands_64[] = {
+    0x81ceb32c4b43fcf5, 0xa2425ff75e14fc32, 0xcad2f7f5359a3b3f,
+    0xfd87b5f28300ca0e, 0x9e74d1b791e07e49, 0xc612062576589ddb,
+    0xf79687aed3eec552, 0x9abe14cd44753b53, 0xc16d9a0095928a28,
+    0xf1c90080baf72cb2, 0x971da05074da7bef, 0xbce5086492111aeb,
+    0xec1e4a7db69561a6, 0x9392ee8e921d5d08, 0xb877aa3236a4b44a,
+    0xe69594bec44de15c, 0x901d7cf73ab0acda, 0xb424dc35095cd810,
+    0xe12e13424bb40e14, 0x8cbccc096f5088cc, 0xafebff0bcb24aaff,
+    0xdbe6fecebdedd5bf, 0x89705f4136b4a598, 0xabcc77118461cefd,
+    0xd6bf94d5e57a42bd, 0x8637bd05af6c69b6, 0xa7c5ac471b478424,
+    0xd1b71758e219652c, 0x83126e978d4fdf3c, 0xa3d70a3d70a3d70b,
+    0xcccccccccccccccd, 0x8000000000000000, 0xa000000000000000,
+    0xc800000000000000, 0xfa00000000000000, 0x9c40000000000000,
+    0xc350000000000000, 0xf424000000000000, 0x9896800000000000,
+    0xbebc200000000000, 0xee6b280000000000, 0x9502f90000000000,
+    0xba43b74000000000, 0xe8d4a51000000000, 0x9184e72a00000000,
+    0xb5e620f480000000, 0xe35fa931a0000000, 0x8e1bc9bf04000000,
+    0xb1a2bc2ec5000000, 0xde0b6b3a76400000, 0x8ac7230489e80000,
+    0xad78ebc5ac620000, 0xd8d726b7177a8000, 0x878678326eac9000,
+    0xa968163f0a57b400, 0xd3c21bcecceda100, 0x84595161401484a0,
+    0xa56fa5b99019a5c8, 0xcecb8f27f4200f3a, 0x813f3978f8940984,
+    0xa18f07d736b90be5, 0xc9f2c9cd04674ede, 0xfc6f7c4045812296,
+    0x9dc5ada82b70b59d, 0xc5371912364ce305, 0xf684df56c3e01bc6,
+    0x9a130b963a6c115c, 0xc097ce7bc90715b3, 0xf0bdc21abb48db20,
+    0x96769950b50d88f4, 0xbc143fa4e250eb31, 0xeb194f8e1ae525fd,
+    0x92efd1b8d0cf37be, 0xb7abc627050305ad, 0xe596b7b0c643c719,
+    0x8f7e32ce7bea5c6f, 0xb35dbf821ae4f38b, 0xe0352f62a19e306e};
+
+template <typename T>
+const uint128_wrapper basic_data<T>::dragonbox_pow10_significands_128[] = {
+#if FMT_USE_FULL_CACHE_DRAGONBOX
+    {0xff77b1fcbebcdc4f, 0x25e8e89c13bb0f7b},
+    {0x9faacf3df73609b1, 0x77b191618c54e9ad},
+    {0xc795830d75038c1d, 0xd59df5b9ef6a2418},
+    {0xf97ae3d0d2446f25, 0x4b0573286b44ad1e},
+    {0x9becce62836ac577, 0x4ee367f9430aec33},
+    {0xc2e801fb244576d5, 0x229c41f793cda740},
+    {0xf3a20279ed56d48a, 0x6b43527578c11110},
+    {0x9845418c345644d6, 0x830a13896b78aaaa},
+    {0xbe5691ef416bd60c, 0x23cc986bc656d554},
+    {0xedec366b11c6cb8f, 0x2cbfbe86b7ec8aa9},
+    {0x94b3a202eb1c3f39, 0x7bf7d71432f3d6aa},
+    {0xb9e08a83a5e34f07, 0xdaf5ccd93fb0cc54},
+    {0xe858ad248f5c22c9, 0xd1b3400f8f9cff69},
+    {0x91376c36d99995be, 0x23100809b9c21fa2},
+    {0xb58547448ffffb2d, 0xabd40a0c2832a78b},
+    {0xe2e69915b3fff9f9, 0x16c90c8f323f516d},
+    {0x8dd01fad907ffc3b, 0xae3da7d97f6792e4},
+    {0xb1442798f49ffb4a, 0x99cd11cfdf41779d},
+    {0xdd95317f31c7fa1d, 0x40405643d711d584},
+    {0x8a7d3eef7f1cfc52, 0x482835ea666b2573},
+    {0xad1c8eab5ee43b66, 0xda3243650005eed0},
+    {0xd863b256369d4a40, 0x90bed43e40076a83},
+    {0x873e4f75e2224e68, 0x5a7744a6e804a292},
+    {0xa90de3535aaae202, 0x711515d0a205cb37},
+    {0xd3515c2831559a83, 0x0d5a5b44ca873e04},
+    {0x8412d9991ed58091, 0xe858790afe9486c3},
+    {0xa5178fff668ae0b6, 0x626e974dbe39a873},
+    {0xce5d73ff402d98e3, 0xfb0a3d212dc81290},
+    {0x80fa687f881c7f8e, 0x7ce66634bc9d0b9a},
+    {0xa139029f6a239f72, 0x1c1fffc1ebc44e81},
+    {0xc987434744ac874e, 0xa327ffb266b56221},
+    {0xfbe9141915d7a922, 0x4bf1ff9f0062baa9},
+    {0x9d71ac8fada6c9b5, 0x6f773fc3603db4aa},
+    {0xc4ce17b399107c22, 0xcb550fb4384d21d4},
+    {0xf6019da07f549b2b, 0x7e2a53a146606a49},
+    {0x99c102844f94e0fb, 0x2eda7444cbfc426e},
+    {0xc0314325637a1939, 0xfa911155fefb5309},
+    {0xf03d93eebc589f88, 0x793555ab7eba27cb},
+    {0x96267c7535b763b5, 0x4bc1558b2f3458df},
+    {0xbbb01b9283253ca2, 0x9eb1aaedfb016f17},
+    {0xea9c227723ee8bcb, 0x465e15a979c1cadd},
+    {0x92a1958a7675175f, 0x0bfacd89ec191eca},
+    {0xb749faed14125d36, 0xcef980ec671f667c},
+    {0xe51c79a85916f484, 0x82b7e12780e7401b},
+    {0x8f31cc0937ae58d2, 0xd1b2ecb8b0908811},
+    {0xb2fe3f0b8599ef07, 0x861fa7e6dcb4aa16},
+    {0xdfbdcece67006ac9, 0x67a791e093e1d49b},
+    {0x8bd6a141006042bd, 0xe0c8bb2c5c6d24e1},
+    {0xaecc49914078536d, 0x58fae9f773886e19},
+    {0xda7f5bf590966848, 0xaf39a475506a899f},
+    {0x888f99797a5e012d, 0x6d8406c952429604},
+    {0xaab37fd7d8f58178, 0xc8e5087ba6d33b84},
+    {0xd5605fcdcf32e1d6, 0xfb1e4a9a90880a65},
+    {0x855c3be0a17fcd26, 0x5cf2eea09a550680},
+    {0xa6b34ad8c9dfc06f, 0xf42faa48c0ea481f},
+    {0xd0601d8efc57b08b, 0xf13b94daf124da27},
+    {0x823c12795db6ce57, 0x76c53d08d6b70859},
+    {0xa2cb1717b52481ed, 0x54768c4b0c64ca6f},
+    {0xcb7ddcdda26da268, 0xa9942f5dcf7dfd0a},
+    {0xfe5d54150b090b02, 0xd3f93b35435d7c4d},
+    {0x9efa548d26e5a6e1, 0xc47bc5014a1a6db0},
+    {0xc6b8e9b0709f109a, 0x359ab6419ca1091c},
+    {0xf867241c8cc6d4c0, 0xc30163d203c94b63},
+    {0x9b407691d7fc44f8, 0x79e0de63425dcf1e},
+    {0xc21094364dfb5636, 0x985915fc12f542e5},
+    {0xf294b943e17a2bc4, 0x3e6f5b7b17b2939e},
+    {0x979cf3ca6cec5b5a, 0xa705992ceecf9c43},
+    {0xbd8430bd08277231, 0x50c6ff782a838354},
+    {0xece53cec4a314ebd, 0xa4f8bf5635246429},
+    {0x940f4613ae5ed136, 0x871b7795e136be9a},
+    {0xb913179899f68584, 0x28e2557b59846e40},
+    {0xe757dd7ec07426e5, 0x331aeada2fe589d0},
+    {0x9096ea6f3848984f, 0x3ff0d2c85def7622},
+    {0xb4bca50b065abe63, 0x0fed077a756b53aa},
+    {0xe1ebce4dc7f16dfb, 0xd3e8495912c62895},
+    {0x8d3360f09cf6e4bd, 0x64712dd7abbbd95d},
+    {0xb080392cc4349dec, 0xbd8d794d96aacfb4},
+    {0xdca04777f541c567, 0xecf0d7a0fc5583a1},
+    {0x89e42caaf9491b60, 0xf41686c49db57245},
+    {0xac5d37d5b79b6239, 0x311c2875c522ced6},
+    {0xd77485cb25823ac7, 0x7d633293366b828c},
+    {0x86a8d39ef77164bc, 0xae5dff9c02033198},
+    {0xa8530886b54dbdeb, 0xd9f57f830283fdfd},
+    {0xd267caa862a12d66, 0xd072df63c324fd7c},
+    {0x8380dea93da4bc60, 0x4247cb9e59f71e6e},
+    {0xa46116538d0deb78, 0x52d9be85f074e609},
+    {0xcd795be870516656, 0x67902e276c921f8c},
+    {0x806bd9714632dff6, 0x00ba1cd8a3db53b7},
+    {0xa086cfcd97bf97f3, 0x80e8a40eccd228a5},
+    {0xc8a883c0fdaf7df0, 0x6122cd128006b2ce},
+    {0xfad2a4b13d1b5d6c, 0x796b805720085f82},
+    {0x9cc3a6eec6311a63, 0xcbe3303674053bb1},
+    {0xc3f490aa77bd60fc, 0xbedbfc4411068a9d},
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+    {0xa4b8cab1a1563f52, 0x577001b891185938},
+    {0xcde6fd5e09abcf26, 0xed4c0226b55e6f86},
+    {0x80b05e5ac60b6178, 0x544f8158315b05b4},
+    {0xa0dc75f1778e39d6, 0x696361ae3db1c721},
+    {0xc913936dd571c84c, 0x03bc3a19cd1e38e9},
+    {0xfb5878494ace3a5f, 0x04ab48a04065c723},
+    {0x9d174b2dcec0e47b, 0x62eb0d64283f9c76},
+    {0xc45d1df942711d9a, 0x3ba5d0bd324f8394},
+    {0xf5746577930d6500, 0xca8f44ec7ee36479},
+    {0x9968bf6abbe85f20, 0x7e998b13cf4e1ecb},
+    {0xbfc2ef456ae276e8, 0x9e3fedd8c321a67e},
+    {0xefb3ab16c59b14a2, 0xc5cfe94ef3ea101e},
+    {0x95d04aee3b80ece5, 0xbba1f1d158724a12},
+    {0xbb445da9ca61281f, 0x2a8a6e45ae8edc97},
+    {0xea1575143cf97226, 0xf52d09d71a3293bd},
+    {0x924d692ca61be758, 0x593c2626705f9c56},
+    {0xb6e0c377cfa2e12e, 0x6f8b2fb00c77836c},
+    {0xe498f455c38b997a, 0x0b6dfb9c0f956447},
+    {0x8edf98b59a373fec, 0x4724bd4189bd5eac},
+    {0xb2977ee300c50fe7, 0x58edec91ec2cb657},
+    {0xdf3d5e9bc0f653e1, 0x2f2967b66737e3ed},
+    {0x8b865b215899f46c, 0xbd79e0d20082ee74},
+    {0xae67f1e9aec07187, 0xecd8590680a3aa11},
+    {0xda01ee641a708de9, 0xe80e6f4820cc9495},
+    {0x884134fe908658b2, 0x3109058d147fdcdd},
+    {0xaa51823e34a7eede, 0xbd4b46f0599fd415},
+    {0xd4e5e2cdc1d1ea96, 0x6c9e18ac7007c91a},
+    {0x850fadc09923329e, 0x03e2cf6bc604ddb0},
+    {0xa6539930bf6bff45, 0x84db8346b786151c},
+    {0xcfe87f7cef46ff16, 0xe612641865679a63},
+    {0x81f14fae158c5f6e, 0x4fcb7e8f3f60c07e},
+    {0xa26da3999aef7749, 0xe3be5e330f38f09d},
+    {0xcb090c8001ab551c, 0x5cadf5bfd3072cc5},
+    {0xfdcb4fa002162a63, 0x73d9732fc7c8f7f6},
+    {0x9e9f11c4014dda7e, 0x2867e7fddcdd9afa},
+    {0xc646d63501a1511d, 0xb281e1fd541501b8},
+    {0xf7d88bc24209a565, 0x1f225a7ca91a4226},
+    {0x9ae757596946075f, 0x3375788de9b06958},
+    {0xc1a12d2fc3978937, 0x0052d6b1641c83ae},
+    {0xf209787bb47d6b84, 0xc0678c5dbd23a49a},
+    {0x9745eb4d50ce6332, 0xf840b7ba963646e0},
+    {0xbd176620a501fbff, 0xb650e5a93bc3d898},
+    {0xec5d3fa8ce427aff, 0xa3e51f138ab4cebe},
+    {0x93ba47c980e98cdf, 0xc66f336c36b10137},
+    {0xb8a8d9bbe123f017, 0xb80b0047445d4184},
+    {0xe6d3102ad96cec1d, 0xa60dc059157491e5},
+    {0x9043ea1ac7e41392, 0x87c89837ad68db2f},
+    {0xb454e4a179dd1877, 0x29babe4598c311fb},
+    {0xe16a1dc9d8545e94, 0xf4296dd6fef3d67a},
+    {0x8ce2529e2734bb1d, 0x1899e4a65f58660c},
+    {0xb01ae745b101e9e4, 0x5ec05dcff72e7f8f},
+    {0xdc21a1171d42645d, 0x76707543f4fa1f73},
+    {0x899504ae72497eba, 0x6a06494a791c53a8},
+    {0xabfa45da0edbde69, 0x0487db9d17636892},
+    {0xd6f8d7509292d603, 0x45a9d2845d3c42b6},
+    {0x865b86925b9bc5c2, 0x0b8a2392ba45a9b2},
+    {0xa7f26836f282b732, 0x8e6cac7768d7141e},
+    {0xd1ef0244af2364ff, 0x3207d795430cd926},
+    {0x8335616aed761f1f, 0x7f44e6bd49e807b8},
+    {0xa402b9c5a8d3a6e7, 0x5f16206c9c6209a6},
+    {0xcd036837130890a1, 0x36dba887c37a8c0f},
+    {0x802221226be55a64, 0xc2494954da2c9789},
+    {0xa02aa96b06deb0fd, 0xf2db9baa10b7bd6c},
+    {0xc83553c5c8965d3d, 0x6f92829494e5acc7},
+    {0xfa42a8b73abbf48c, 0xcb772339ba1f17f9},
+    {0x9c69a97284b578d7, 0xff2a760414536efb},
+    {0xc38413cf25e2d70d, 0xfef5138519684aba},
+    {0xf46518c2ef5b8cd1, 0x7eb258665fc25d69},
+    {0x98bf2f79d5993802, 0xef2f773ffbd97a61},
+    {0xbeeefb584aff8603, 0xaafb550ffacfd8fa},
+    {0xeeaaba2e5dbf6784, 0x95ba2a53f983cf38},
+    {0x952ab45cfa97a0b2, 0xdd945a747bf26183},
+    {0xba756174393d88df, 0x94f971119aeef9e4},
+    {0xe912b9d1478ceb17, 0x7a37cd5601aab85d},
+    {0x91abb422ccb812ee, 0xac62e055c10ab33a},
+    {0xb616a12b7fe617aa, 0x577b986b314d6009},
+    {0xe39c49765fdf9d94, 0xed5a7e85fda0b80b},
+    {0x8e41ade9fbebc27d, 0x14588f13be847307},
+    {0xb1d219647ae6b31c, 0x596eb2d8ae258fc8},
+    {0xde469fbd99a05fe3, 0x6fca5f8ed9aef3bb},
+    {0x8aec23d680043bee, 0x25de7bb9480d5854},
+    {0xada72ccc20054ae9, 0xaf561aa79a10ae6a},
+    {0xd910f7ff28069da4, 0x1b2ba1518094da04},
+    {0x87aa9aff79042286, 0x90fb44d2f05d0842},
+    {0xa99541bf57452b28, 0x353a1607ac744a53},
+    {0xd3fa922f2d1675f2, 0x42889b8997915ce8},
+    {0x847c9b5d7c2e09b7, 0x69956135febada11},
+    {0xa59bc234db398c25, 0x43fab9837e699095},
+    {0xcf02b2c21207ef2e, 0x94f967e45e03f4bb},
+    {0x8161afb94b44f57d, 0x1d1be0eebac278f5},
+    {0xa1ba1ba79e1632dc, 0x6462d92a69731732},
+    {0xca28a291859bbf93, 0x7d7b8f7503cfdcfe},
+    {0xfcb2cb35e702af78, 0x5cda735244c3d43e},
+    {0x9defbf01b061adab, 0x3a0888136afa64a7},
+    {0xc56baec21c7a1916, 0x088aaa1845b8fdd0},
+    {0xf6c69a72a3989f5b, 0x8aad549e57273d45},
+    {0x9a3c2087a63f6399, 0x36ac54e2f678864b},
+    {0xc0cb28a98fcf3c7f, 0x84576a1bb416a7dd},
+    {0xf0fdf2d3f3c30b9f, 0x656d44a2a11c51d5},
+    {0x969eb7c47859e743, 0x9f644ae5a4b1b325},
+    {0xbc4665b596706114, 0x873d5d9f0dde1fee},
+    {0xeb57ff22fc0c7959, 0xa90cb506d155a7ea},
+    {0x9316ff75dd87cbd8, 0x09a7f12442d588f2},
+    {0xb7dcbf5354e9bece, 0x0c11ed6d538aeb2f},
+    {0xe5d3ef282a242e81, 0x8f1668c8a86da5fa},
+    {0x8fa475791a569d10, 0xf96e017d694487bc},
+    {0xb38d92d760ec4455, 0x37c981dcc395a9ac},
+    {0xe070f78d3927556a, 0x85bbe253f47b1417},
+    {0x8c469ab843b89562, 0x93956d7478ccec8e},
+    {0xaf58416654a6babb, 0x387ac8d1970027b2},
+    {0xdb2e51bfe9d0696a, 0x06997b05fcc0319e},
+    {0x88fcf317f22241e2, 0x441fece3bdf81f03},
+    {0xab3c2fddeeaad25a, 0xd527e81cad7626c3},
+    {0xd60b3bd56a5586f1, 0x8a71e223d8d3b074},
+    {0x85c7056562757456, 0xf6872d5667844e49},
+    {0xa738c6bebb12d16c, 0xb428f8ac016561db},
+    {0xd106f86e69d785c7, 0xe13336d701beba52},
+    {0x82a45b450226b39c, 0xecc0024661173473},
+    {0xa34d721642b06084, 0x27f002d7f95d0190},
+    {0xcc20ce9bd35c78a5, 0x31ec038df7b441f4},
+    {0xff290242c83396ce, 0x7e67047175a15271},
+    {0x9f79a169bd203e41, 0x0f0062c6e984d386},
+    {0xc75809c42c684dd1, 0x52c07b78a3e60868},
+    {0xf92e0c3537826145, 0xa7709a56ccdf8a82},
+    {0x9bbcc7a142b17ccb, 0x88a66076400bb691},
+    {0xc2abf989935ddbfe, 0x6acff893d00ea435},
+    {0xf356f7ebf83552fe, 0x0583f6b8c4124d43},
+    {0x98165af37b2153de, 0xc3727a337a8b704a},
+    {0xbe1bf1b059e9a8d6, 0x744f18c0592e4c5c},
+    {0xeda2ee1c7064130c, 0x1162def06f79df73},
+    {0x9485d4d1c63e8be7, 0x8addcb5645ac2ba8},
+    {0xb9a74a0637ce2ee1, 0x6d953e2bd7173692},
+    {0xe8111c87c5c1ba99, 0xc8fa8db6ccdd0437},
+    {0x910ab1d4db9914a0, 0x1d9c9892400a22a2},
+    {0xb54d5e4a127f59c8, 0x2503beb6d00cab4b},
+    {0xe2a0b5dc971f303a, 0x2e44ae64840fd61d},
+    {0x8da471a9de737e24, 0x5ceaecfed289e5d2},
+    {0xb10d8e1456105dad, 0x7425a83e872c5f47},
+    {0xdd50f1996b947518, 0xd12f124e28f77719},
+    {0x8a5296ffe33cc92f, 0x82bd6b70d99aaa6f},
+    {0xace73cbfdc0bfb7b, 0x636cc64d1001550b},
+    {0xd8210befd30efa5a, 0x3c47f7e05401aa4e},
+    {0x8714a775e3e95c78, 0x65acfaec34810a71},
+    {0xa8d9d1535ce3b396, 0x7f1839a741a14d0d},
+    {0xd31045a8341ca07c, 0x1ede48111209a050},
+    {0x83ea2b892091e44d, 0x934aed0aab460432},
+    {0xa4e4b66b68b65d60, 0xf81da84d5617853f},
+    {0xce1de40642e3f4b9, 0x36251260ab9d668e},
+    {0x80d2ae83e9ce78f3, 0xc1d72b7c6b426019},
+    {0xa1075a24e4421730, 0xb24cf65b8612f81f},
+    {0xc94930ae1d529cfc, 0xdee033f26797b627},
+    {0xfb9b7cd9a4a7443c, 0x169840ef017da3b1},
+    {0x9d412e0806e88aa5, 0x8e1f289560ee864e},
+    {0xc491798a08a2ad4e, 0xf1a6f2bab92a27e2},
+    {0xf5b5d7ec8acb58a2, 0xae10af696774b1db},
+    {0x9991a6f3d6bf1765, 0xacca6da1e0a8ef29},
+    {0xbff610b0cc6edd3f, 0x17fd090a58d32af3},
+    {0xeff394dcff8a948e, 0xddfc4b4cef07f5b0},
+    {0x95f83d0a1fb69cd9, 0x4abdaf101564f98e},
+    {0xbb764c4ca7a4440f, 0x9d6d1ad41abe37f1},
+    {0xea53df5fd18d5513, 0x84c86189216dc5ed},
+    {0x92746b9be2f8552c, 0x32fd3cf5b4e49bb4},
+    {0xb7118682dbb66a77, 0x3fbc8c33221dc2a1},
+    {0xe4d5e82392a40515, 0x0fabaf3feaa5334a},
+    {0x8f05b1163ba6832d, 0x29cb4d87f2a7400e},
+    {0xb2c71d5bca9023f8, 0x743e20e9ef511012},
+    {0xdf78e4b2bd342cf6, 0x914da9246b255416},
+    {0x8bab8eefb6409c1a, 0x1ad089b6c2f7548e},
+    {0xae9672aba3d0c320, 0xa184ac2473b529b1},
+    {0xda3c0f568cc4f3e8, 0xc9e5d72d90a2741e},
+    {0x8865899617fb1871, 0x7e2fa67c7a658892},
+    {0xaa7eebfb9df9de8d, 0xddbb901b98feeab7},
+    {0xd51ea6fa85785631, 0x552a74227f3ea565},
+    {0x8533285c936b35de, 0xd53a88958f87275f},
+    {0xa67ff273b8460356, 0x8a892abaf368f137},
+    {0xd01fef10a657842c, 0x2d2b7569b0432d85},
+    {0x8213f56a67f6b29b, 0x9c3b29620e29fc73},
+    {0xa298f2c501f45f42, 0x8349f3ba91b47b8f},
+    {0xcb3f2f7642717713, 0x241c70a936219a73},
+    {0xfe0efb53d30dd4d7, 0xed238cd383aa0110},
+    {0x9ec95d1463e8a506, 0xf4363804324a40aa},
+    {0xc67bb4597ce2ce48, 0xb143c6053edcd0d5},
+    {0xf81aa16fdc1b81da, 0xdd94b7868e94050a},
+    {0x9b10a4e5e9913128, 0xca7cf2b4191c8326},
+    {0xc1d4ce1f63f57d72, 0xfd1c2f611f63a3f0},
+    {0xf24a01a73cf2dccf, 0xbc633b39673c8cec},
+    {0x976e41088617ca01, 0xd5be0503e085d813},
+    {0xbd49d14aa79dbc82, 0x4b2d8644d8a74e18},
+    {0xec9c459d51852ba2, 0xddf8e7d60ed1219e},
+    {0x93e1ab8252f33b45, 0xcabb90e5c942b503},
+    {0xb8da1662e7b00a17, 0x3d6a751f3b936243},
+    {0xe7109bfba19c0c9d, 0x0cc512670a783ad4},
+    {0x906a617d450187e2, 0x27fb2b80668b24c5},
+    {0xb484f9dc9641e9da, 0xb1f9f660802dedf6},
+    {0xe1a63853bbd26451, 0x5e7873f8a0396973},
+    {0x8d07e33455637eb2, 0xdb0b487b6423e1e8},
+    {0xb049dc016abc5e5f, 0x91ce1a9a3d2cda62},
+    {0xdc5c5301c56b75f7, 0x7641a140cc7810fb},
+    {0x89b9b3e11b6329ba, 0xa9e904c87fcb0a9d},
+    {0xac2820d9623bf429, 0x546345fa9fbdcd44},
+    {0xd732290fbacaf133, 0xa97c177947ad4095},
+    {0x867f59a9d4bed6c0, 0x49ed8eabcccc485d},
+    {0xa81f301449ee8c70, 0x5c68f256bfff5a74},
+    {0xd226fc195c6a2f8c, 0x73832eec6fff3111},
+    {0x83585d8fd9c25db7, 0xc831fd53c5ff7eab},
+    {0xa42e74f3d032f525, 0xba3e7ca8b77f5e55},
+    {0xcd3a1230c43fb26f, 0x28ce1bd2e55f35eb},
+    {0x80444b5e7aa7cf85, 0x7980d163cf5b81b3},
+    {0xa0555e361951c366, 0xd7e105bcc332621f},
+    {0xc86ab5c39fa63440, 0x8dd9472bf3fefaa7},
+    {0xfa856334878fc150, 0xb14f98f6f0feb951},
+    {0x9c935e00d4b9d8d2, 0x6ed1bf9a569f33d3},
+    {0xc3b8358109e84f07, 0x0a862f80ec4700c8},
+    {0xf4a642e14c6262c8, 0xcd27bb612758c0fa},
+    {0x98e7e9cccfbd7dbd, 0x8038d51cb897789c},
+    {0xbf21e44003acdd2c, 0xe0470a63e6bd56c3},
+    {0xeeea5d5004981478, 0x1858ccfce06cac74},
+    {0x95527a5202df0ccb, 0x0f37801e0c43ebc8},
+    {0xbaa718e68396cffd, 0xd30560258f54e6ba},
+    {0xe950df20247c83fd, 0x47c6b82ef32a2069},
+    {0x91d28b7416cdd27e, 0x4cdc331d57fa5441},
+    {0xb6472e511c81471d, 0xe0133fe4adf8e952},
+    {0xe3d8f9e563a198e5, 0x58180fddd97723a6},
+    {0x8e679c2f5e44ff8f, 0x570f09eaa7ea7648},
+    {0xb201833b35d63f73, 0x2cd2cc6551e513da},
+    {0xde81e40a034bcf4f, 0xf8077f7ea65e58d1},
+    {0x8b112e86420f6191, 0xfb04afaf27faf782},
+    {0xadd57a27d29339f6, 0x79c5db9af1f9b563},
+    {0xd94ad8b1c7380874, 0x18375281ae7822bc},
+    {0x87cec76f1c830548, 0x8f2293910d0b15b5},
+    {0xa9c2794ae3a3c69a, 0xb2eb3875504ddb22},
+    {0xd433179d9c8cb841, 0x5fa60692a46151eb},
+    {0x849feec281d7f328, 0xdbc7c41ba6bcd333},
+    {0xa5c7ea73224deff3, 0x12b9b522906c0800},
+    {0xcf39e50feae16bef, 0xd768226b34870a00},
+    {0x81842f29f2cce375, 0xe6a1158300d46640},
+    {0xa1e53af46f801c53, 0x60495ae3c1097fd0},
+    {0xca5e89b18b602368, 0x385bb19cb14bdfc4},
+    {0xfcf62c1dee382c42, 0x46729e03dd9ed7b5},
+    {0x9e19db92b4e31ba9, 0x6c07a2c26a8346d1},
+    {0xc5a05277621be293, 0xc7098b7305241885},
+    {0xf70867153aa2db38, 0xb8cbee4fc66d1ea7}
+#else
+    {0xff77b1fcbebcdc4f, 0x25e8e89c13bb0f7b},
+    {0xce5d73ff402d98e3, 0xfb0a3d212dc81290},
+    {0xa6b34ad8c9dfc06f, 0xf42faa48c0ea481f},
+    {0x86a8d39ef77164bc, 0xae5dff9c02033198},
+    {0xd98ddaee19068c76, 0x3badd624dd9b0958},
+    {0xafbd2350644eeacf, 0xe5d1929ef90898fb},
+    {0x8df5efabc5979c8f, 0xca8d3ffa1ef463c2},
+    {0xe55990879ddcaabd, 0xcc420a6a101d0516},
+    {0xb94470938fa89bce, 0xf808e40e8d5b3e6a},
+    {0x95a8637627989aad, 0xdde7001379a44aa9},
+    {0xf1c90080baf72cb1, 0x5324c68b12dd6339},
+    {0xc350000000000000, 0x0000000000000000},
+    {0x9dc5ada82b70b59d, 0xf020000000000000},
+    {0xfee50b7025c36a08, 0x02f236d04753d5b4},
+    {0xcde6fd5e09abcf26, 0xed4c0226b55e6f86},
+    {0xa6539930bf6bff45, 0x84db8346b786151c},
+    {0x865b86925b9bc5c2, 0x0b8a2392ba45a9b2},
+    {0xd910f7ff28069da4, 0x1b2ba1518094da04},
+    {0xaf58416654a6babb, 0x387ac8d1970027b2},
+    {0x8da471a9de737e24, 0x5ceaecfed289e5d2},
+    {0xe4d5e82392a40515, 0x0fabaf3feaa5334a},
+    {0xb8da1662e7b00a17, 0x3d6a751f3b936243},
+    {0x95527a5202df0ccb, 0x0f37801e0c43ebc8}
+#endif
+};
+
+#if !FMT_USE_FULL_CACHE_DRAGONBOX
+template <typename T>
+const uint64_t basic_data<T>::powers_of_5_64[] = {
+    0x0000000000000001, 0x0000000000000005, 0x0000000000000019,
+    0x000000000000007d, 0x0000000000000271, 0x0000000000000c35,
+    0x0000000000003d09, 0x000000000001312d, 0x000000000005f5e1,
+    0x00000000001dcd65, 0x00000000009502f9, 0x0000000002e90edd,
+    0x000000000e8d4a51, 0x0000000048c27395, 0x000000016bcc41e9,
+    0x000000071afd498d, 0x0000002386f26fc1, 0x000000b1a2bc2ec5,
+    0x000003782dace9d9, 0x00001158e460913d, 0x000056bc75e2d631,
+    0x0001b1ae4d6e2ef5, 0x000878678326eac9, 0x002a5a058fc295ed,
+    0x00d3c21bcecceda1, 0x0422ca8b0a00a425, 0x14adf4b7320334b9};
+
+template <typename T>
+const uint32_t basic_data<T>::dragonbox_pow10_recovery_errors[] = {
+    0x50001400, 0x54044100, 0x54014555, 0x55954415, 0x54115555, 0x00000001,
+    0x50000000, 0x00104000, 0x54010004, 0x05004001, 0x55555544, 0x41545555,
+    0x54040551, 0x15445545, 0x51555514, 0x10000015, 0x00101100, 0x01100015,
+    0x00000000, 0x00000000, 0x00000000, 0x00000000, 0x04450514, 0x45414110,
+    0x55555145, 0x50544050, 0x15040155, 0x11054140, 0x50111514, 0x11451454,
+    0x00400541, 0x00000000, 0x55555450, 0x10056551, 0x10054011, 0x55551014,
+    0x69514555, 0x05151109, 0x00155555};
+#endif
+
+template <typename T>
+const char basic_data<T>::foreground_color[] = "\x1b[38;2;";
+template <typename T>
+const char basic_data<T>::background_color[] = "\x1b[48;2;";
+template <typename T> const char basic_data<T>::reset_color[] = "\x1b[0m";
+template <typename T> const wchar_t basic_data<T>::wreset_color[] = L"\x1b[0m";
+template <typename T> const char basic_data<T>::signs[] = {0, '-', '+', ' '};
+template <typename T>
+const char basic_data<T>::left_padding_shifts[] = {31, 31, 0, 1, 0};
+template <typename T>
+const char basic_data<T>::right_padding_shifts[] = {0, 31, 0, 1, 0};
+
+template <typename T> struct bits {
+  static FMT_CONSTEXPR_DECL const int value =
+      static_cast<int>(sizeof(T) * std::numeric_limits<unsigned char>::digits);
+};
+
+class fp;
+template <int SHIFT = 0> fp normalize(fp value);
+
+// Lower (upper) boundary is a value half way between a floating-point value
+// and its predecessor (successor). Boundaries have the same exponent as the
+// value so only significands are stored.
+struct boundaries {
+  uint64_t lower;
+  uint64_t upper;
+};
+
+// A handmade floating-point number f * pow(2, e).
+class fp {
+ private:
+  using significand_type = uint64_t;
+
+  template <typename Float>
+  using is_supported_float = bool_constant<sizeof(Float) == sizeof(uint64_t) ||
+                                           sizeof(Float) == sizeof(uint32_t)>;
+
+ public:
+  significand_type f;
+  int e;
+
+  // All sizes are in bits.
+  // Subtract 1 to account for an implicit most significant bit in the
+  // normalized form.
+  static FMT_CONSTEXPR_DECL const int double_significand_size =
+      std::numeric_limits<double>::digits - 1;
+  static FMT_CONSTEXPR_DECL const uint64_t implicit_bit =
+      1ULL << double_significand_size;
+  static FMT_CONSTEXPR_DECL const int significand_size =
+      bits<significand_type>::value;
+
+  fp() : f(0), e(0) {}
+  fp(uint64_t f_val, int e_val) : f(f_val), e(e_val) {}
+
+  // Constructs fp from an IEEE754 double. It is a template to prevent compile
+  // errors on platforms where double is not IEEE754.
+  template <typename Double> explicit fp(Double d) { assign(d); }
+
+  // Assigns d to this and return true iff predecessor is closer than successor.
+  template <typename Float, FMT_ENABLE_IF(is_supported_float<Float>::value)>
+  bool assign(Float d) {
+    // Assume float is in the format [sign][exponent][significand].
+    using limits = std::numeric_limits<Float>;
+    const int float_significand_size = limits::digits - 1;
+    const int exponent_size =
+        bits<Float>::value - float_significand_size - 1;  // -1 for sign
+    const uint64_t float_implicit_bit = 1ULL << float_significand_size;
+    const uint64_t significand_mask = float_implicit_bit - 1;
+    const uint64_t exponent_mask = (~0ULL >> 1) & ~significand_mask;
+    const int exponent_bias = (1 << exponent_size) - limits::max_exponent - 1;
+    constexpr bool is_double = sizeof(Float) == sizeof(uint64_t);
+    auto u = bit_cast<conditional_t<is_double, uint64_t, uint32_t>>(d);
+    f = u & significand_mask;
+    int biased_e =
+        static_cast<int>((u & exponent_mask) >> float_significand_size);
+    // Predecessor is closer if d is a normalized power of 2 (f == 0) other than
+    // the smallest normalized number (biased_e > 1).
+    bool is_predecessor_closer = f == 0 && biased_e > 1;
+    if (biased_e != 0)
+      f += float_implicit_bit;
+    else
+      biased_e = 1;  // Subnormals use biased exponent 1 (min exponent).
+    e = biased_e - exponent_bias - float_significand_size;
+    return is_predecessor_closer;
+  }
+
+  template <typename Float, FMT_ENABLE_IF(!is_supported_float<Float>::value)>
+  bool assign(Float) {
+    *this = fp();
+    return false;
+  }
+};
+
+// Normalizes the value converted from double and multiplied by (1 << SHIFT).
+template <int SHIFT> fp normalize(fp value) {
+  // Handle subnormals.
+  const auto shifted_implicit_bit = fp::implicit_bit << SHIFT;
+  while ((value.f & shifted_implicit_bit) == 0) {
+    value.f <<= 1;
+    --value.e;
+  }
+  // Subtract 1 to account for hidden bit.
+  const auto offset =
+      fp::significand_size - fp::double_significand_size - SHIFT - 1;
+  value.f <<= offset;
+  value.e -= offset;
+  return value;
 }
+
+inline bool operator==(fp x, fp y) { return x.f == y.f && x.e == y.e; }
+
+// Computes lhs * rhs / pow(2, 64) rounded to nearest with half-up tie breaking.
+inline uint64_t multiply(uint64_t lhs, uint64_t rhs) {
+#if FMT_USE_INT128
+  auto product = static_cast<__uint128_t>(lhs) * rhs;
+  auto f = static_cast<uint64_t>(product >> 64);
+  return (static_cast<uint64_t>(product) & (1ULL << 63)) != 0 ? f + 1 : f;
+#else
+  // Multiply 32-bit parts of significands.
+  uint64_t mask = (1ULL << 32) - 1;
+  uint64_t a = lhs >> 32, b = lhs & mask;
+  uint64_t c = rhs >> 32, d = rhs & mask;
+  uint64_t ac = a * c, bc = b * c, ad = a * d, bd = b * d;
+  // Compute mid 64-bit of result and round.
+  uint64_t mid = (bd >> 32) + (ad & mask) + (bc & mask) + (1U << 31);
+  return ac + (ad >> 32) + (bc >> 32) + (mid >> 32);
 #endif
+}
 
-FMT_FUNC std::system_error vsystem_error(int error_code, string_view fmt,
-                                         format_args args) {
-  auto ec = std::error_code(error_code, std::generic_category());
-  return std::system_error(ec, vformat(fmt, args));
+inline fp operator*(fp x, fp y) { return {multiply(x.f, y.f), x.e + y.e + 64}; }
+
+// Returns a cached power of 10 `c_k = c_k.f * pow(2, c_k.e)` such that its
+// (binary) exponent satisfies `min_exponent <= c_k.e <= min_exponent + 28`.
+inline fp get_cached_power(int min_exponent, int& pow10_exponent) {
+  const int shift = 32;
+  const auto significand = static_cast<int64_t>(data::log10_2_significand);
+  int index = static_cast<int>(
+      ((min_exponent + fp::significand_size - 1) * (significand >> shift) +
+       ((int64_t(1) << shift) - 1))  // ceil
+      >> 32                          // arithmetic shift
+  );
+  // Decimal exponent of the first (smallest) cached power of 10.
+  const int first_dec_exp = -348;
+  // Difference between 2 consecutive decimal exponents in cached powers of 10.
+  const int dec_exp_step = 8;
+  index = (index - first_dec_exp - 1) / dec_exp_step + 1;
+  pow10_exponent = first_dec_exp + index * dec_exp_step;
+  return {data::grisu_pow10_significands[index],
+          data::grisu_pow10_exponents[index]};
 }
 
-namespace detail {
+// A simple accumulator to hold the sums of terms in bigint::square if uint128_t
+// is not available.
+struct accumulator {
+  uint64_t lower;
+  uint64_t upper;
+
+  accumulator() : lower(0), upper(0) {}
+  explicit operator uint32_t() const { return static_cast<uint32_t>(lower); }
+
+  void operator+=(uint64_t n) {
+    lower += n;
+    if (lower < n) ++upper;
+  }
+  void operator>>=(int shift) {
+    assert(shift == 32);
+    (void)shift;
+    lower = (upper << 32) | (lower >> 32);
+    upper >>= 32;
+  }
+};
+
+class bigint {
+ private:
+  // A bigint is stored as an array of bigits (big digits), with bigit at index
+  // 0 being the least significant one.
+  using bigit = uint32_t;
+  using double_bigit = uint64_t;
+  enum { bigits_capacity = 32 };
+  basic_memory_buffer<bigit, bigits_capacity> bigits_;
+  int exp_;
+
+  bigit operator[](int index) const { return bigits_[to_unsigned(index)]; }
+  bigit& operator[](int index) { return bigits_[to_unsigned(index)]; }
+
+  static FMT_CONSTEXPR_DECL const int bigit_bits = bits<bigit>::value;
+
+  friend struct formatter<bigint>;
+
+  void subtract_bigits(int index, bigit other, bigit& borrow) {
+    auto result = static_cast<double_bigit>((*this)[index]) - other - borrow;
+    (*this)[index] = static_cast<bigit>(result);
+    borrow = static_cast<bigit>(result >> (bigit_bits * 2 - 1));
+  }
+
+  void remove_leading_zeros() {
+    int num_bigits = static_cast<int>(bigits_.size()) - 1;
+    while (num_bigits > 0 && (*this)[num_bigits] == 0) --num_bigits;
+    bigits_.resize(to_unsigned(num_bigits + 1));
+  }
+
+  // Computes *this -= other assuming aligned bigints and *this >= other.
+  void subtract_aligned(const bigint& other) {
+    FMT_ASSERT(other.exp_ >= exp_, "unaligned bigints");
+    FMT_ASSERT(compare(*this, other) >= 0, "");
+    bigit borrow = 0;
+    int i = other.exp_ - exp_;
+    for (size_t j = 0, n = other.bigits_.size(); j != n; ++i, ++j)
+      subtract_bigits(i, other.bigits_[j], borrow);
+    while (borrow > 0) subtract_bigits(i, 0, borrow);
+    remove_leading_zeros();
+  }
+
+  void multiply(uint32_t value) {
+    const double_bigit wide_value = value;
+    bigit carry = 0;
+    for (size_t i = 0, n = bigits_.size(); i < n; ++i) {
+      double_bigit result = bigits_[i] * wide_value + carry;
+      bigits_[i] = static_cast<bigit>(result);
+      carry = static_cast<bigit>(result >> bigit_bits);
+    }
+    if (carry != 0) bigits_.push_back(carry);
+  }
+
+  void multiply(uint64_t value) {
+    const bigit mask = ~bigit(0);
+    const double_bigit lower = value & mask;
+    const double_bigit upper = value >> bigit_bits;
+    double_bigit carry = 0;
+    for (size_t i = 0, n = bigits_.size(); i < n; ++i) {
+      double_bigit result = bigits_[i] * lower + (carry & mask);
+      carry =
+          bigits_[i] * upper + (result >> bigit_bits) + (carry >> bigit_bits);
+      bigits_[i] = static_cast<bigit>(result);
+    }
+    while (carry != 0) {
+      bigits_.push_back(carry & mask);
+      carry >>= bigit_bits;
+    }
+  }
+
+ public:
+  bigint() : exp_(0) {}
+  explicit bigint(uint64_t n) { assign(n); }
+  ~bigint() { assert(bigits_.capacity() <= bigits_capacity); }
+
+  bigint(const bigint&) = delete;
+  void operator=(const bigint&) = delete;
+
+  void assign(const bigint& other) {
+    auto size = other.bigits_.size();
+    bigits_.resize(size);
+    auto data = other.bigits_.data();
+    std::copy(data, data + size, make_checked(bigits_.data(), size));
+    exp_ = other.exp_;
+  }
+
+  void assign(uint64_t n) {
+    size_t num_bigits = 0;
+    do {
+      bigits_[num_bigits++] = n & ~bigit(0);
+      n >>= bigit_bits;
+    } while (n != 0);
+    bigits_.resize(num_bigits);
+    exp_ = 0;
+  }
+
+  int num_bigits() const { return static_cast<int>(bigits_.size()) + exp_; }
+
+  FMT_NOINLINE bigint& operator<<=(int shift) {
+    assert(shift >= 0);
+    exp_ += shift / bigit_bits;
+    shift %= bigit_bits;
+    if (shift == 0) return *this;
+    bigit carry = 0;
+    for (size_t i = 0, n = bigits_.size(); i < n; ++i) {
+      bigit c = bigits_[i] >> (bigit_bits - shift);
+      bigits_[i] = (bigits_[i] << shift) + carry;
+      carry = c;
+    }
+    if (carry != 0) bigits_.push_back(carry);
+    return *this;
+  }
+
+  template <typename Int> bigint& operator*=(Int value) {
+    FMT_ASSERT(value > 0, "");
+    multiply(uint32_or_64_or_128_t<Int>(value));
+    return *this;
+  }
+
+  friend int compare(const bigint& lhs, const bigint& rhs) {
+    int num_lhs_bigits = lhs.num_bigits(), num_rhs_bigits = rhs.num_bigits();
+    if (num_lhs_bigits != num_rhs_bigits)
+      return num_lhs_bigits > num_rhs_bigits ? 1 : -1;
+    int i = static_cast<int>(lhs.bigits_.size()) - 1;
+    int j = static_cast<int>(rhs.bigits_.size()) - 1;
+    int end = i - j;
+    if (end < 0) end = 0;
+    for (; i >= end; --i, --j) {
+      bigit lhs_bigit = lhs[i], rhs_bigit = rhs[j];
+      if (lhs_bigit != rhs_bigit) return lhs_bigit > rhs_bigit ? 1 : -1;
+    }
+    if (i != j) return i > j ? 1 : -1;
+    return 0;
+  }
 
-template <typename F> inline bool operator==(basic_fp<F> x, basic_fp<F> y) {
-  return x.f == y.f && x.e == y.e;
+  // Returns compare(lhs1 + lhs2, rhs).
+  friend int add_compare(const bigint& lhs1, const bigint& lhs2,
+                         const bigint& rhs) {
+    int max_lhs_bigits = (std::max)(lhs1.num_bigits(), lhs2.num_bigits());
+    int num_rhs_bigits = rhs.num_bigits();
+    if (max_lhs_bigits + 1 < num_rhs_bigits) return -1;
+    if (max_lhs_bigits > num_rhs_bigits) return 1;
+    auto get_bigit = [](const bigint& n, int i) -> bigit {
+      return i >= n.exp_ && i < n.num_bigits() ? n[i - n.exp_] : 0;
+    };
+    double_bigit borrow = 0;
+    int min_exp = (std::min)((std::min)(lhs1.exp_, lhs2.exp_), rhs.exp_);
+    for (int i = num_rhs_bigits - 1; i >= min_exp; --i) {
+      double_bigit sum =
+          static_cast<double_bigit>(get_bigit(lhs1, i)) + get_bigit(lhs2, i);
+      bigit rhs_bigit = get_bigit(rhs, i);
+      if (sum > rhs_bigit + borrow) return 1;
+      borrow = rhs_bigit + borrow - sum;
+      if (borrow > 1) return -1;
+      borrow <<= bigit_bits;
+    }
+    return borrow != 0 ? -1 : 0;
+  }
+
+  // Assigns pow(10, exp) to this bigint.
+  void assign_pow10(int exp) {
+    assert(exp >= 0);
+    if (exp == 0) return assign(1);
+    // Find the top bit.
+    int bitmask = 1;
+    while (exp >= bitmask) bitmask <<= 1;
+    bitmask >>= 1;
+    // pow(10, exp) = pow(5, exp) * pow(2, exp). First compute pow(5, exp) by
+    // repeated squaring and multiplication.
+    assign(5);
+    bitmask >>= 1;
+    while (bitmask != 0) {
+      square();
+      if ((exp & bitmask) != 0) *this *= 5;
+      bitmask >>= 1;
+    }
+    *this <<= exp;  // Multiply by pow(2, exp) by shifting.
+  }
+
+  void square() {
+    basic_memory_buffer<bigit, bigits_capacity> n(std::move(bigits_));
+    int num_bigits = static_cast<int>(bigits_.size());
+    int num_result_bigits = 2 * num_bigits;
+    bigits_.resize(to_unsigned(num_result_bigits));
+    using accumulator_t = conditional_t<FMT_USE_INT128, uint128_t, accumulator>;
+    auto sum = accumulator_t();
+    for (int bigit_index = 0; bigit_index < num_bigits; ++bigit_index) {
+      // Compute bigit at position bigit_index of the result by adding
+      // cross-product terms n[i] * n[j] such that i + j == bigit_index.
+      for (int i = 0, j = bigit_index; j >= 0; ++i, --j) {
+        // Most terms are multiplied twice which can be optimized in the future.
+        sum += static_cast<double_bigit>(n[i]) * n[j];
+      }
+      (*this)[bigit_index] = static_cast<bigit>(sum);
+      sum >>= bits<bigit>::value;  // Compute the carry.
+    }
+    // Do the same for the top half.
+    for (int bigit_index = num_bigits; bigit_index < num_result_bigits;
+         ++bigit_index) {
+      for (int j = num_bigits - 1, i = bigit_index - j; i < num_bigits;)
+        sum += static_cast<double_bigit>(n[i++]) * n[j--];
+      (*this)[bigit_index] = static_cast<bigit>(sum);
+      sum >>= bits<bigit>::value;
+    }
+    --num_result_bigits;
+    remove_leading_zeros();
+    exp_ *= 2;
+  }
+
+  // If this bigint has a bigger exponent than other, adds trailing zero to make
+  // exponents equal. This simplifies some operations such as subtraction.
+  void align(const bigint& other) {
+    int exp_difference = exp_ - other.exp_;
+    if (exp_difference <= 0) return;
+    int num_bigits = static_cast<int>(bigits_.size());
+    bigits_.resize(to_unsigned(num_bigits + exp_difference));
+    for (int i = num_bigits - 1, j = i + exp_difference; i >= 0; --i, --j)
+      bigits_[j] = bigits_[i];
+    std::uninitialized_fill_n(bigits_.data(), exp_difference, 0);
+    exp_ -= exp_difference;
+  }
+
+  // Divides this bignum by divisor, assigning the remainder to this and
+  // returning the quotient.
+  int divmod_assign(const bigint& divisor) {
+    FMT_ASSERT(this != &divisor, "");
+    if (compare(*this, divisor) < 0) return 0;
+    FMT_ASSERT(divisor.bigits_[divisor.bigits_.size() - 1u] != 0, "");
+    align(divisor);
+    int quotient = 0;
+    do {
+      subtract_aligned(divisor);
+      ++quotient;
+    } while (compare(*this, divisor) >= 0);
+    return quotient;
+  }
+};
+
+enum class round_direction { unknown, up, down };
+
+// Given the divisor (normally a power of 10), the remainder = v % divisor for
+// some number v and the error, returns whether v should be rounded up, down, or
+// whether the rounding direction can't be determined due to error.
+// error should be less than divisor / 2.
+inline round_direction get_round_direction(uint64_t divisor, uint64_t remainder,
+                                           uint64_t error) {
+  FMT_ASSERT(remainder < divisor, "");  // divisor - remainder won't overflow.
+  FMT_ASSERT(error < divisor, "");      // divisor - error won't overflow.
+  FMT_ASSERT(error < divisor - error, "");  // error * 2 won't overflow.
+  // Round down if (remainder + error) * 2 <= divisor.
+  if (remainder <= divisor - remainder && error * 2 <= divisor - remainder * 2)
+    return round_direction::down;
+  // Round up if (remainder - error) * 2 >= divisor.
+  if (remainder >= error &&
+      remainder - error >= divisor - (remainder - error)) {
+    return round_direction::up;
+  }
+  return round_direction::unknown;
 }
 
-// Compilers should be able to optimize this into the ror instruction.
-FMT_CONSTEXPR inline uint32_t rotr(uint32_t n, uint32_t r) noexcept {
-  r &= 31;
-  return (n >> r) | (n << (32 - r));
+namespace digits {
+enum result {
+  more,  // Generate more digits.
+  done,  // Done generating digits.
+  error  // Digit generation cancelled due to an error.
+};
 }
-FMT_CONSTEXPR inline uint64_t rotr(uint64_t n, uint32_t r) noexcept {
-  r &= 63;
-  return (n >> r) | (n << (64 - r));
+
+// Generates output using the Grisu digit-gen algorithm.
+// error: the size of the region (lower, upper) outside of which numbers
+// definitely do not round to value (Delta in Grisu3).
+template <typename Handler>
+FMT_ALWAYS_INLINE digits::result grisu_gen_digits(fp value, uint64_t error,
+                                                  int& exp, Handler& handler) {
+  const fp one(1ULL << -value.e, value.e);
+  // The integral part of scaled value (p1 in Grisu) = value / one. It cannot be
+  // zero because it contains a product of two 64-bit numbers with MSB set (due
+  // to normalization) - 1, shifted right by at most 60 bits.
+  auto integral = static_cast<uint32_t>(value.f >> -one.e);
+  FMT_ASSERT(integral != 0, "");
+  FMT_ASSERT(integral == value.f >> -one.e, "");
+  // The fractional part of scaled value (p2 in Grisu) c = value % one.
+  uint64_t fractional = value.f & (one.f - 1);
+  exp = count_digits(integral);  // kappa in Grisu.
+  // Divide by 10 to prevent overflow.
+  auto result = handler.on_start(data::powers_of_10_64[exp - 1] << -one.e,
+                                 value.f / 10, error * 10, exp);
+  if (result != digits::more) return result;
+  // Generate digits for the integral part. This can produce up to 10 digits.
+  do {
+    uint32_t digit = 0;
+    auto divmod_integral = [&](uint32_t divisor) {
+      digit = integral / divisor;
+      integral %= divisor;
+    };
+    // This optimization by Milo Yip reduces the number of integer divisions by
+    // one per iteration.
+    switch (exp) {
+    case 10:
+      divmod_integral(1000000000);
+      break;
+    case 9:
+      divmod_integral(100000000);
+      break;
+    case 8:
+      divmod_integral(10000000);
+      break;
+    case 7:
+      divmod_integral(1000000);
+      break;
+    case 6:
+      divmod_integral(100000);
+      break;
+    case 5:
+      divmod_integral(10000);
+      break;
+    case 4:
+      divmod_integral(1000);
+      break;
+    case 3:
+      divmod_integral(100);
+      break;
+    case 2:
+      divmod_integral(10);
+      break;
+    case 1:
+      digit = integral;
+      integral = 0;
+      break;
+    default:
+      FMT_ASSERT(false, "invalid number of digits");
+    }
+    --exp;
+    auto remainder = (static_cast<uint64_t>(integral) << -one.e) + fractional;
+    result = handler.on_digit(static_cast<char>('0' + digit),
+                              data::powers_of_10_64[exp] << -one.e, remainder,
+                              error, exp, true);
+    if (result != digits::more) return result;
+  } while (exp > 0);
+  // Generate digits for the fractional part.
+  for (;;) {
+    fractional *= 10;
+    error *= 10;
+    char digit = static_cast<char>('0' + (fractional >> -one.e));
+    fractional &= one.f - 1;
+    --exp;
+    result = handler.on_digit(digit, one.f, fractional, error, exp, false);
+    if (result != digits::more) return result;
+  }
 }
 
+// The fixed precision digit handler.
+struct fixed_handler {
+  char* buf;
+  int size;
+  int precision;
+  int exp10;
+  bool fixed;
+
+  digits::result on_start(uint64_t divisor, uint64_t remainder, uint64_t error,
+                          int& exp) {
+    // Non-fixed formats require at least one digit and no precision adjustment.
+    if (!fixed) return digits::more;
+    // Adjust fixed precision by exponent because it is relative to decimal
+    // point.
+    precision += exp + exp10;
+    // Check if precision is satisfied just by leading zeros, e.g.
+    // format("{:.2f}", 0.001) gives "0.00" without generating any digits.
+    if (precision > 0) return digits::more;
+    if (precision < 0) return digits::done;
+    auto dir = get_round_direction(divisor, remainder, error);
+    if (dir == round_direction::unknown) return digits::error;
+    buf[size++] = dir == round_direction::up ? '1' : '0';
+    return digits::done;
+  }
+
+  digits::result on_digit(char digit, uint64_t divisor, uint64_t remainder,
+                          uint64_t error, int, bool integral) {
+    FMT_ASSERT(remainder < divisor, "");
+    buf[size++] = digit;
+    if (!integral && error >= remainder) return digits::error;
+    if (size < precision) return digits::more;
+    if (!integral) {
+      // Check if error * 2 < divisor with overflow prevention.
+      // The check is not needed for the integral part because error = 1
+      // and divisor > (1 << 32) there.
+      if (error >= divisor || error >= divisor - error) return digits::error;
+    } else {
+      FMT_ASSERT(error == 1 && divisor > 2, "");
+    }
+    auto dir = get_round_direction(divisor, remainder, error);
+    if (dir != round_direction::up)
+      return dir == round_direction::down ? digits::done : digits::error;
+    ++buf[size - 1];
+    for (int i = size - 1; i > 0 && buf[i] > '9'; --i) {
+      buf[i] = '0';
+      ++buf[i - 1];
+    }
+    if (buf[0] > '9') {
+      buf[0] = '1';
+      if (fixed)
+        buf[size++] = '0';
+      else
+        ++exp10;
+    }
+    return digits::done;
+  }
+};
+
 // Implementation of Dragonbox algorithm: https://github.com/jk-jeon/dragonbox.
 namespace dragonbox {
-// Computes upper 64 bits of multiplication of a 32-bit unsigned integer and a
+// Computes 128-bit result of multiplication of two 64-bit unsigned integers.
+FMT_SAFEBUFFERS inline uint128_wrapper umul128(uint64_t x,
+                                               uint64_t y) FMT_NOEXCEPT {
+#if FMT_USE_INT128
+  return static_cast<uint128_t>(x) * static_cast<uint128_t>(y);
+#elif defined(_MSC_VER) && defined(_M_X64)
+  uint128_wrapper result;
+  result.low_ = _umul128(x, y, &result.high_);
+  return result;
+#else
+  const uint64_t mask = (uint64_t(1) << 32) - uint64_t(1);
+
+  uint64_t a = x >> 32;
+  uint64_t b = x & mask;
+  uint64_t c = y >> 32;
+  uint64_t d = y & mask;
+
+  uint64_t ac = a * c;
+  uint64_t bc = b * c;
+  uint64_t ad = a * d;
+  uint64_t bd = b * d;
+
+  uint64_t intermediate = (bd >> 32) + (ad & mask) + (bc & mask);
+
+  return {ac + (intermediate >> 32) + (ad >> 32) + (bc >> 32),
+          (intermediate << 32) + (bd & mask)};
+#endif
+}
+
+// Computes upper 64 bits of multiplication of two 64-bit unsigned integers.
+FMT_SAFEBUFFERS inline uint64_t umul128_upper64(uint64_t x,
+                                                uint64_t y) FMT_NOEXCEPT {
+#if FMT_USE_INT128
+  auto p = static_cast<uint128_t>(x) * static_cast<uint128_t>(y);
+  return static_cast<uint64_t>(p >> 64);
+#elif defined(_MSC_VER) && defined(_M_X64)
+  return __umulh(x, y);
+#else
+  return umul128(x, y).high();
+#endif
+}
+
+// Computes upper 64 bits of multiplication of a 64-bit unsigned integer and a
+// 128-bit unsigned integer.
+FMT_SAFEBUFFERS inline uint64_t umul192_upper64(uint64_t x, uint128_wrapper y)
+    FMT_NOEXCEPT {
+  uint128_wrapper g0 = umul128(x, y.high());
+  g0 += umul128_upper64(x, y.low());
+  return g0.high();
+}
+
+// Computes upper 32 bits of multiplication of a 32-bit unsigned integer and a
 // 64-bit unsigned integer.
-inline uint64_t umul96_upper64(uint32_t x, uint64_t y) noexcept {
-  return umul128_upper64(static_cast<uint64_t>(x) << 32, y);
+inline uint32_t umul96_upper32(uint32_t x, uint64_t y) FMT_NOEXCEPT {
+  return static_cast<uint32_t>(umul128_upper64(x, y));
 }
 
-// Computes lower 128 bits of multiplication of a 64-bit unsigned integer and a
+// Computes middle 64 bits of multiplication of a 64-bit unsigned integer and a
 // 128-bit unsigned integer.
-inline uint128_fallback umul192_lower128(uint64_t x,
-                                         uint128_fallback y) noexcept {
-  uint64_t high = x * y.high();
-  uint128_fallback high_low = umul128(x, y.low());
-  return {high + high_low.high(), high_low.low()};
+FMT_SAFEBUFFERS inline uint64_t umul192_middle64(uint64_t x, uint128_wrapper y)
+    FMT_NOEXCEPT {
+  uint64_t g01 = x * y.high();
+  uint64_t g10 = umul128_upper64(x, y.low());
+  return g01 + g10;
 }
 
 // Computes lower 64 bits of multiplication of a 32-bit unsigned integer and a
 // 64-bit unsigned integer.
-inline uint64_t umul96_lower64(uint32_t x, uint64_t y) noexcept {
+inline uint64_t umul96_lower64(uint32_t x, uint64_t y) FMT_NOEXCEPT {
   return x * y;
 }
 
+// Computes floor(log10(pow(2, e))) for e in [-1700, 1700] using the method from
+// https://fmt.dev/papers/Grisu-Exact.pdf#page=5, section 3.4.
+inline int floor_log10_pow2(int e) FMT_NOEXCEPT {
+  FMT_ASSERT(e <= 1700 && e >= -1700, "too large exponent");
+  const int shift = 22;
+  return (e * static_cast<int>(data::log10_2_significand >> (64 - shift))) >>
+         shift;
+}
+
 // Various fast log computations.
-inline int floor_log10_pow2_minus_log10_4_over_3(int e) noexcept {
-  FMT_ASSERT(e <= 2936 && e >= -2985, "too large exponent");
-  return (e * 631305 - 261663) >> 21;
+inline int floor_log2_pow10(int e) FMT_NOEXCEPT {
+  FMT_ASSERT(e <= 1233 && e >= -1233, "too large exponent");
+  const uint64_t log2_10_integer_part = 3;
+  const uint64_t log2_10_fractional_digits = 0x5269e12f346e2bf9;
+  const int shift_amount = 19;
+  return (e * static_cast<int>(
+                  (log2_10_integer_part << shift_amount) |
+                  (log2_10_fractional_digits >> (64 - shift_amount)))) >>
+         shift_amount;
+}
+inline int floor_log10_pow2_minus_log10_4_over_3(int e) FMT_NOEXCEPT {
+  FMT_ASSERT(e <= 1700 && e >= -1700, "too large exponent");
+  const uint64_t log10_4_over_3_fractional_digits = 0x1ffbfc2bbc780375;
+  const int shift_amount = 22;
+  return (e * static_cast<int>(data::log10_2_significand >>
+                               (64 - shift_amount)) -
+          static_cast<int>(log10_4_over_3_fractional_digits >>
+                           (64 - shift_amount))) >>
+         shift_amount;
 }
 
-FMT_INLINE_VARIABLE constexpr struct {
-  uint32_t divisor;
-  int shift_amount;
-} div_small_pow10_infos[] = {{10, 16}, {100, 16}};
+// Returns true iff x is divisible by pow(2, exp).
+inline bool divisible_by_power_of_2(uint32_t x, int exp) FMT_NOEXCEPT {
+  FMT_ASSERT(exp >= 1, "");
+  FMT_ASSERT(x != 0, "");
+#ifdef FMT_BUILTIN_CTZ
+  return FMT_BUILTIN_CTZ(x) >= exp;
+#else
+  return exp < num_bits<uint32_t>() && x == ((x >> exp) << exp);
+#endif
+}
+inline bool divisible_by_power_of_2(uint64_t x, int exp) FMT_NOEXCEPT {
+  FMT_ASSERT(exp >= 1, "");
+  FMT_ASSERT(x != 0, "");
+#ifdef FMT_BUILTIN_CTZLL
+  return FMT_BUILTIN_CTZLL(x) >= exp;
+#else
+  return exp < num_bits<uint64_t>() && x == ((x >> exp) << exp);
+#endif
+}
 
-// Replaces n by floor(n / pow(10, N)) returning true if and only if n is
-// divisible by pow(10, N).
-// Precondition: n <= pow(10, N + 1).
+// Returns true iff x is divisible by pow(5, exp).
+inline bool divisible_by_power_of_5(uint32_t x, int exp) FMT_NOEXCEPT {
+  FMT_ASSERT(exp <= 10, "too large exponent");
+  return x * data::divtest_table_for_pow5_32[exp].mod_inv <=
+         data::divtest_table_for_pow5_32[exp].max_quotient;
+}
+inline bool divisible_by_power_of_5(uint64_t x, int exp) FMT_NOEXCEPT {
+  FMT_ASSERT(exp <= 23, "too large exponent");
+  return x * data::divtest_table_for_pow5_64[exp].mod_inv <=
+         data::divtest_table_for_pow5_64[exp].max_quotient;
+}
+
+// Replaces n by floor(n / pow(5, N)) returning true if and only if n is
+// divisible by pow(5, N).
+// Precondition: n <= 2 * pow(5, N + 1).
 template <int N>
-bool check_divisibility_and_divide_by_pow10(uint32_t& n) noexcept {
-  // The numbers below are chosen such that:
-  //   1. floor(n/d) = floor(nm / 2^k) where d=10 or d=100,
-  //   2. nm mod 2^k < m if and only if n is divisible by d,
-  // where m is magic_number, k is shift_amount
-  // and d is divisor.
-  //
-  // Item 1 is a common technique of replacing division by a constant with
-  // multiplication, see e.g. "Division by Invariant Integers Using
-  // Multiplication" by Granlund and Montgomery (1994). magic_number (m) is set
-  // to ceil(2^k/d) for large enough k.
-  // The idea for item 2 originates from Schubfach.
-  constexpr auto info = div_small_pow10_infos[N - 1];
-  FMT_ASSERT(n <= info.divisor * 10, "n is too large");
-  constexpr uint32_t magic_number =
-      (1u << info.shift_amount) / info.divisor + 1;
-  n *= magic_number;
-  const uint32_t comparison_mask = (1u << info.shift_amount) - 1;
-  bool result = (n & comparison_mask) < magic_number;
+bool check_divisibility_and_divide_by_pow5(uint32_t& n) FMT_NOEXCEPT {
+  static constexpr struct {
+    uint32_t magic_number;
+    int bits_for_comparison;
+    uint32_t threshold;
+    int shift_amount;
+  } infos[] = {{0xcccd, 16, 0x3333, 18}, {0xa429, 8, 0x0a, 20}};
+  constexpr auto info = infos[N - 1];
+  n *= info.magic_number;
+  const uint32_t comparison_mask = (1u << info.bits_for_comparison) - 1;
+  bool result = (n & comparison_mask) <= info.threshold;
   n >>= info.shift_amount;
   return result;
 }
 
 // Computes floor(n / pow(10, N)) for small n and N.
 // Precondition: n <= pow(10, N + 1).
-template <int N> uint32_t small_division_by_pow10(uint32_t n) noexcept {
-  constexpr auto info = div_small_pow10_infos[N - 1];
-  FMT_ASSERT(n <= info.divisor * 10, "n is too large");
-  constexpr uint32_t magic_number =
-      (1u << info.shift_amount) / info.divisor + 1;
-  return (n * magic_number) >> info.shift_amount;
+template <int N> uint32_t small_division_by_pow10(uint32_t n) FMT_NOEXCEPT {
+  static constexpr struct {
+    uint32_t magic_number;
+    int shift_amount;
+    uint32_t divisor_times_10;
+  } infos[] = {{0xcccd, 19, 100}, {0xa3d8, 22, 1000}};
+  constexpr auto info = infos[N - 1];
+  FMT_ASSERT(n <= info.divisor_times_10, "n is too large");
+  return n * info.magic_number >> info.shift_amount;
 }
 
 // Computes floor(n / 10^(kappa + 1)) (float)
-inline uint32_t divide_by_10_to_kappa_plus_1(uint32_t n) noexcept {
-  // 1374389535 = ceil(2^37/100)
-  return static_cast<uint32_t>((static_cast<uint64_t>(n) * 1374389535) >> 37);
+inline uint32_t divide_by_10_to_kappa_plus_1(uint32_t n) FMT_NOEXCEPT {
+  return n / float_info<float>::big_divisor;
 }
 // Computes floor(n / 10^(kappa + 1)) (double)
-inline uint64_t divide_by_10_to_kappa_plus_1(uint64_t n) noexcept {
-  // 2361183241434822607 = ceil(2^(64+7)/1000)
-  return umul128_upper64(n, 2361183241434822607ull) >> 7;
+inline uint64_t divide_by_10_to_kappa_plus_1(uint64_t n) FMT_NOEXCEPT {
+  return umul128_upper64(n, 0x83126e978d4fdf3c) >> 9;
 }
 
 // Various subroutines using pow10 cache
-template <typename T> struct cache_accessor;
+template <class T> struct cache_accessor;
 
 template <> struct cache_accessor<float> {
   using carrier_uint = float_info<float>::carrier_uint;
   using cache_entry_type = uint64_t;
 
-  static uint64_t get_cached_power(int k) noexcept {
+  static uint64_t get_cached_power(int k) FMT_NOEXCEPT {
     FMT_ASSERT(k >= float_info<float>::min_k && k <= float_info<float>::max_k,
                "k is out of range");
-    static constexpr const uint64_t pow10_significands[] = {
-        0x81ceb32c4b43fcf5, 0xa2425ff75e14fc32, 0xcad2f7f5359a3b3f,
-        0xfd87b5f28300ca0e, 0x9e74d1b791e07e49, 0xc612062576589ddb,
-        0xf79687aed3eec552, 0x9abe14cd44753b53, 0xc16d9a0095928a28,
-        0xf1c90080baf72cb2, 0x971da05074da7bef, 0xbce5086492111aeb,
-        0xec1e4a7db69561a6, 0x9392ee8e921d5d08, 0xb877aa3236a4b44a,
-        0xe69594bec44de15c, 0x901d7cf73ab0acda, 0xb424dc35095cd810,
-        0xe12e13424bb40e14, 0x8cbccc096f5088cc, 0xafebff0bcb24aaff,
-        0xdbe6fecebdedd5bf, 0x89705f4136b4a598, 0xabcc77118461cefd,
-        0xd6bf94d5e57a42bd, 0x8637bd05af6c69b6, 0xa7c5ac471b478424,
-        0xd1b71758e219652c, 0x83126e978d4fdf3c, 0xa3d70a3d70a3d70b,
-        0xcccccccccccccccd, 0x8000000000000000, 0xa000000000000000,
-        0xc800000000000000, 0xfa00000000000000, 0x9c40000000000000,
-        0xc350000000000000, 0xf424000000000000, 0x9896800000000000,
-        0xbebc200000000000, 0xee6b280000000000, 0x9502f90000000000,
-        0xba43b74000000000, 0xe8d4a51000000000, 0x9184e72a00000000,
-        0xb5e620f480000000, 0xe35fa931a0000000, 0x8e1bc9bf04000000,
-        0xb1a2bc2ec5000000, 0xde0b6b3a76400000, 0x8ac7230489e80000,
-        0xad78ebc5ac620000, 0xd8d726b7177a8000, 0x878678326eac9000,
-        0xa968163f0a57b400, 0xd3c21bcecceda100, 0x84595161401484a0,
-        0xa56fa5b99019a5c8, 0xcecb8f27f4200f3a, 0x813f3978f8940985,
-        0xa18f07d736b90be6, 0xc9f2c9cd04674edf, 0xfc6f7c4045812297,
-        0x9dc5ada82b70b59e, 0xc5371912364ce306, 0xf684df56c3e01bc7,
-        0x9a130b963a6c115d, 0xc097ce7bc90715b4, 0xf0bdc21abb48db21,
-        0x96769950b50d88f5, 0xbc143fa4e250eb32, 0xeb194f8e1ae525fe,
-        0x92efd1b8d0cf37bf, 0xb7abc627050305ae, 0xe596b7b0c643c71a,
-        0x8f7e32ce7bea5c70, 0xb35dbf821ae4f38c, 0xe0352f62a19e306f};
-    return pow10_significands[k - float_info<float>::min_k];
-  }
-
-  struct compute_mul_result {
-    carrier_uint result;
-    bool is_integer;
-  };
-  struct compute_mul_parity_result {
-    bool parity;
-    bool is_integer;
-  };
+    return data::dragonbox_pow10_significands_64[k - float_info<float>::min_k];
+  }
 
-  static compute_mul_result compute_mul(
-      carrier_uint u, const cache_entry_type& cache) noexcept {
-    auto r = umul96_upper64(u, cache);
-    return {static_cast<carrier_uint>(r >> 32),
-            static_cast<carrier_uint>(r) == 0};
+  static carrier_uint compute_mul(carrier_uint u,
+                                  const cache_entry_type& cache) FMT_NOEXCEPT {
+    return umul96_upper32(u, cache);
   }
 
   static uint32_t compute_delta(const cache_entry_type& cache,
-                                int beta) noexcept {
-    return static_cast<uint32_t>(cache >> (64 - 1 - beta));
+                                int beta_minus_1) FMT_NOEXCEPT {
+    return static_cast<uint32_t>(cache >> (64 - 1 - beta_minus_1));
   }
 
-  static compute_mul_parity_result compute_mul_parity(
-      carrier_uint two_f, const cache_entry_type& cache, int beta) noexcept {
-    FMT_ASSERT(beta >= 1, "");
-    FMT_ASSERT(beta < 64, "");
+  static bool compute_mul_parity(carrier_uint two_f,
+                                 const cache_entry_type& cache,
+                                 int beta_minus_1) FMT_NOEXCEPT {
+    FMT_ASSERT(beta_minus_1 >= 1, "");
+    FMT_ASSERT(beta_minus_1 < 64, "");
 
-    auto r = umul96_lower64(two_f, cache);
-    return {((r >> (64 - beta)) & 1) != 0,
-            static_cast<uint32_t>(r >> (32 - beta)) == 0};
+    return ((umul96_lower64(two_f, cache) >> (64 - beta_minus_1)) & 1) != 0;
   }
 
   static carrier_uint compute_left_endpoint_for_shorter_interval_case(
-      const cache_entry_type& cache, int beta) noexcept {
+      const cache_entry_type& cache, int beta_minus_1) FMT_NOEXCEPT {
     return static_cast<carrier_uint>(
-        (cache - (cache >> (num_significand_bits<float>() + 2))) >>
-        (64 - num_significand_bits<float>() - 1 - beta));
+        (cache - (cache >> (float_info<float>::significand_bits + 2))) >>
+        (64 - float_info<float>::significand_bits - 1 - beta_minus_1));
   }
 
   static carrier_uint compute_right_endpoint_for_shorter_interval_case(
-      const cache_entry_type& cache, int beta) noexcept {
+      const cache_entry_type& cache, int beta_minus_1) FMT_NOEXCEPT {
     return static_cast<carrier_uint>(
-        (cache + (cache >> (num_significand_bits<float>() + 1))) >>
-        (64 - num_significand_bits<float>() - 1 - beta));
+        (cache + (cache >> (float_info<float>::significand_bits + 1))) >>
+        (64 - float_info<float>::significand_bits - 1 - beta_minus_1));
   }
 
   static carrier_uint compute_round_up_for_shorter_interval_case(
-      const cache_entry_type& cache, int beta) noexcept {
+      const cache_entry_type& cache, int beta_minus_1) FMT_NOEXCEPT {
     return (static_cast<carrier_uint>(
-                cache >> (64 - num_significand_bits<float>() - 2 - beta)) +
+                cache >>
+                (64 - float_info<float>::significand_bits - 2 - beta_minus_1)) +
             1) /
            2;
   }
@@ -343,690 +1879,16 @@ template <> struct cache_accessor<float> {
 
 template <> struct cache_accessor<double> {
   using carrier_uint = float_info<double>::carrier_uint;
-  using cache_entry_type = uint128_fallback;
+  using cache_entry_type = uint128_wrapper;
 
-  static uint128_fallback get_cached_power(int k) noexcept {
+  static uint128_wrapper get_cached_power(int k) FMT_NOEXCEPT {
     FMT_ASSERT(k >= float_info<double>::min_k && k <= float_info<double>::max_k,
                "k is out of range");
 
-    static constexpr const uint128_fallback pow10_significands[] = {
 #if FMT_USE_FULL_CACHE_DRAGONBOX
-      {0xff77b1fcbebcdc4f, 0x25e8e89c13bb0f7b},
-      {0x9faacf3df73609b1, 0x77b191618c54e9ad},
-      {0xc795830d75038c1d, 0xd59df5b9ef6a2418},
-      {0xf97ae3d0d2446f25, 0x4b0573286b44ad1e},
-      {0x9becce62836ac577, 0x4ee367f9430aec33},
-      {0xc2e801fb244576d5, 0x229c41f793cda740},
-      {0xf3a20279ed56d48a, 0x6b43527578c11110},
-      {0x9845418c345644d6, 0x830a13896b78aaaa},
-      {0xbe5691ef416bd60c, 0x23cc986bc656d554},
-      {0xedec366b11c6cb8f, 0x2cbfbe86b7ec8aa9},
-      {0x94b3a202eb1c3f39, 0x7bf7d71432f3d6aa},
-      {0xb9e08a83a5e34f07, 0xdaf5ccd93fb0cc54},
-      {0xe858ad248f5c22c9, 0xd1b3400f8f9cff69},
-      {0x91376c36d99995be, 0x23100809b9c21fa2},
-      {0xb58547448ffffb2d, 0xabd40a0c2832a78b},
-      {0xe2e69915b3fff9f9, 0x16c90c8f323f516d},
-      {0x8dd01fad907ffc3b, 0xae3da7d97f6792e4},
-      {0xb1442798f49ffb4a, 0x99cd11cfdf41779d},
-      {0xdd95317f31c7fa1d, 0x40405643d711d584},
-      {0x8a7d3eef7f1cfc52, 0x482835ea666b2573},
-      {0xad1c8eab5ee43b66, 0xda3243650005eed0},
-      {0xd863b256369d4a40, 0x90bed43e40076a83},
-      {0x873e4f75e2224e68, 0x5a7744a6e804a292},
-      {0xa90de3535aaae202, 0x711515d0a205cb37},
-      {0xd3515c2831559a83, 0x0d5a5b44ca873e04},
-      {0x8412d9991ed58091, 0xe858790afe9486c3},
-      {0xa5178fff668ae0b6, 0x626e974dbe39a873},
-      {0xce5d73ff402d98e3, 0xfb0a3d212dc81290},
-      {0x80fa687f881c7f8e, 0x7ce66634bc9d0b9a},
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-      {0xfa856334878fc150, 0xb14f98f6f0feb952},
-      {0x9c935e00d4b9d8d2, 0x6ed1bf9a569f33d4},
-      {0xc3b8358109e84f07, 0x0a862f80ec4700c9},
-      {0xf4a642e14c6262c8, 0xcd27bb612758c0fb},
-      {0x98e7e9cccfbd7dbd, 0x8038d51cb897789d},
-      {0xbf21e44003acdd2c, 0xe0470a63e6bd56c4},
-      {0xeeea5d5004981478, 0x1858ccfce06cac75},
-      {0x95527a5202df0ccb, 0x0f37801e0c43ebc9},
-      {0xbaa718e68396cffd, 0xd30560258f54e6bb},
-      {0xe950df20247c83fd, 0x47c6b82ef32a206a},
-      {0x91d28b7416cdd27e, 0x4cdc331d57fa5442},
-      {0xb6472e511c81471d, 0xe0133fe4adf8e953},
-      {0xe3d8f9e563a198e5, 0x58180fddd97723a7},
-      {0x8e679c2f5e44ff8f, 0x570f09eaa7ea7649},
-      {0xb201833b35d63f73, 0x2cd2cc6551e513db},
-      {0xde81e40a034bcf4f, 0xf8077f7ea65e58d2},
-      {0x8b112e86420f6191, 0xfb04afaf27faf783},
-      {0xadd57a27d29339f6, 0x79c5db9af1f9b564},
-      {0xd94ad8b1c7380874, 0x18375281ae7822bd},
-      {0x87cec76f1c830548, 0x8f2293910d0b15b6},
-      {0xa9c2794ae3a3c69a, 0xb2eb3875504ddb23},
-      {0xd433179d9c8cb841, 0x5fa60692a46151ec},
-      {0x849feec281d7f328, 0xdbc7c41ba6bcd334},
-      {0xa5c7ea73224deff3, 0x12b9b522906c0801},
-      {0xcf39e50feae16bef, 0xd768226b34870a01},
-      {0x81842f29f2cce375, 0xe6a1158300d46641},
-      {0xa1e53af46f801c53, 0x60495ae3c1097fd1},
-      {0xca5e89b18b602368, 0x385bb19cb14bdfc5},
-      {0xfcf62c1dee382c42, 0x46729e03dd9ed7b6},
-      {0x9e19db92b4e31ba9, 0x6c07a2c26a8346d2},
-      {0xc5a05277621be293, 0xc7098b7305241886},
-      {0xf70867153aa2db38, 0xb8cbee4fc66d1ea8},
-      {0x9a65406d44a5c903, 0x737f74f1dc043329},
-      {0xc0fe908895cf3b44, 0x505f522e53053ff3},
-      {0xf13e34aabb430a15, 0x647726b9e7c68ff0},
-      {0x96c6e0eab509e64d, 0x5eca783430dc19f6},
-      {0xbc789925624c5fe0, 0xb67d16413d132073},
-      {0xeb96bf6ebadf77d8, 0xe41c5bd18c57e890},
-      {0x933e37a534cbaae7, 0x8e91b962f7b6f15a},
-      {0xb80dc58e81fe95a1, 0x723627bbb5a4adb1},
-      {0xe61136f2227e3b09, 0xcec3b1aaa30dd91d},
-      {0x8fcac257558ee4e6, 0x213a4f0aa5e8a7b2},
-      {0xb3bd72ed2af29e1f, 0xa988e2cd4f62d19e},
-      {0xe0accfa875af45a7, 0x93eb1b80a33b8606},
-      {0x8c6c01c9498d8b88, 0xbc72f130660533c4},
-      {0xaf87023b9bf0ee6a, 0xeb8fad7c7f8680b5},
-      {0xdb68c2ca82ed2a05, 0xa67398db9f6820e2}
+    return data::dragonbox_pow10_significands_128[k -
+                                                  float_info<double>::min_k];
 #else
-      {0xff77b1fcbebcdc4f, 0x25e8e89c13bb0f7b},
-      {0xce5d73ff402d98e3, 0xfb0a3d212dc81290},
-      {0xa6b34ad8c9dfc06f, 0xf42faa48c0ea481f},
-      {0x86a8d39ef77164bc, 0xae5dff9c02033198},
-      {0xd98ddaee19068c76, 0x3badd624dd9b0958},
-      {0xafbd2350644eeacf, 0xe5d1929ef90898fb},
-      {0x8df5efabc5979c8f, 0xca8d3ffa1ef463c2},
-      {0xe55990879ddcaabd, 0xcc420a6a101d0516},
-      {0xb94470938fa89bce, 0xf808e40e8d5b3e6a},
-      {0x95a8637627989aad, 0xdde7001379a44aa9},
-      {0xf1c90080baf72cb1, 0x5324c68b12dd6339},
-      {0xc350000000000000, 0x0000000000000000},
-      {0x9dc5ada82b70b59d, 0xf020000000000000},
-      {0xfee50b7025c36a08, 0x02f236d04753d5b5},
-      {0xcde6fd5e09abcf26, 0xed4c0226b55e6f87},
-      {0xa6539930bf6bff45, 0x84db8346b786151d},
-      {0x865b86925b9bc5c2, 0x0b8a2392ba45a9b3},
-      {0xd910f7ff28069da4, 0x1b2ba1518094da05},
-      {0xaf58416654a6babb, 0x387ac8d1970027b3},
-      {0x8da471a9de737e24, 0x5ceaecfed289e5d3},
-      {0xe4d5e82392a40515, 0x0fabaf3feaa5334b},
-      {0xb8da1662e7b00a17, 0x3d6a751f3b936244},
-      {0x95527a5202df0ccb, 0x0f37801e0c43ebc9},
-      {0xf13e34aabb430a15, 0x647726b9e7c68ff0}
-#endif
-    };
-
-#if FMT_USE_FULL_CACHE_DRAGONBOX
-    return pow10_significands[k - float_info<double>::min_k];
-#else
-    static constexpr const uint64_t powers_of_5_64[] = {
-        0x0000000000000001, 0x0000000000000005, 0x0000000000000019,
-        0x000000000000007d, 0x0000000000000271, 0x0000000000000c35,
-        0x0000000000003d09, 0x000000000001312d, 0x000000000005f5e1,
-        0x00000000001dcd65, 0x00000000009502f9, 0x0000000002e90edd,
-        0x000000000e8d4a51, 0x0000000048c27395, 0x000000016bcc41e9,
-        0x000000071afd498d, 0x0000002386f26fc1, 0x000000b1a2bc2ec5,
-        0x000003782dace9d9, 0x00001158e460913d, 0x000056bc75e2d631,
-        0x0001b1ae4d6e2ef5, 0x000878678326eac9, 0x002a5a058fc295ed,
-        0x00d3c21bcecceda1, 0x0422ca8b0a00a425, 0x14adf4b7320334b9};
-
     static const int compression_ratio = 27;
 
     // Compute base index.
@@ -1035,7 +1897,8 @@ template <> struct cache_accessor<double> {
     int offset = k - kb;
 
     // Get base cache.
-    uint128_fallback base_cache = pow10_significands[cache_index];
+    uint128_wrapper base_cache =
+        data::dragonbox_pow10_significands_128[cache_index];
     if (offset == 0) return base_cache;
 
     // Compute the required amount of bit-shift.
@@ -1043,9 +1906,10 @@ template <> struct cache_accessor<double> {
     FMT_ASSERT(alpha > 0 && alpha < 64, "shifting error detected");
 
     // Try to recover the real cache.
-    uint64_t pow5 = powers_of_5_64[offset];
-    uint128_fallback recovered_cache = umul128(base_cache.high(), pow5);
-    uint128_fallback middle_low = umul128(base_cache.low(), pow5);
+    uint64_t pow5 = data::powers_of_5_64[offset];
+    uint128_wrapper recovered_cache = umul128(base_cache.high(), pow5);
+    uint128_wrapper middle_low =
+        umul128(base_cache.low() - (kb < 0 ? 1u : 0u), pow5);
 
     recovered_cache += middle_low.high();
 
@@ -1053,153 +1917,228 @@ template <> struct cache_accessor<double> {
     uint64_t middle_to_low = recovered_cache.low() << (64 - alpha);
 
     recovered_cache =
-        uint128_fallback{(recovered_cache.low() >> alpha) | high_to_middle,
-                         ((middle_low.low() >> alpha) | middle_to_low)};
-    FMT_ASSERT(recovered_cache.low() + 1 != 0, "");
-    return {recovered_cache.high(), recovered_cache.low() + 1};
+        uint128_wrapper{(recovered_cache.low() >> alpha) | high_to_middle,
+                        ((middle_low.low() >> alpha) | middle_to_low)};
+
+    if (kb < 0) recovered_cache += 1;
+
+    // Get error.
+    int error_idx = (k - float_info<double>::min_k) / 16;
+    uint32_t error = (data::dragonbox_pow10_recovery_errors[error_idx] >>
+                      ((k - float_info<double>::min_k) % 16) * 2) &
+                     0x3;
+
+    // Add the error back.
+    FMT_ASSERT(recovered_cache.low() + error >= recovered_cache.low(), "");
+    return {recovered_cache.high(), recovered_cache.low() + error};
 #endif
   }
 
-  struct compute_mul_result {
-    carrier_uint result;
-    bool is_integer;
-  };
-  struct compute_mul_parity_result {
-    bool parity;
-    bool is_integer;
-  };
-
-  static compute_mul_result compute_mul(
-      carrier_uint u, const cache_entry_type& cache) noexcept {
-    auto r = umul192_upper128(u, cache);
-    return {r.high(), r.low() == 0};
+  static carrier_uint compute_mul(carrier_uint u,
+                                  const cache_entry_type& cache) FMT_NOEXCEPT {
+    return umul192_upper64(u, cache);
   }
 
   static uint32_t compute_delta(cache_entry_type const& cache,
-                                int beta) noexcept {
-    return static_cast<uint32_t>(cache.high() >> (64 - 1 - beta));
+                                int beta_minus_1) FMT_NOEXCEPT {
+    return static_cast<uint32_t>(cache.high() >> (64 - 1 - beta_minus_1));
   }
 
-  static compute_mul_parity_result compute_mul_parity(
-      carrier_uint two_f, const cache_entry_type& cache, int beta) noexcept {
-    FMT_ASSERT(beta >= 1, "");
-    FMT_ASSERT(beta < 64, "");
+  static bool compute_mul_parity(carrier_uint two_f,
+                                 const cache_entry_type& cache,
+                                 int beta_minus_1) FMT_NOEXCEPT {
+    FMT_ASSERT(beta_minus_1 >= 1, "");
+    FMT_ASSERT(beta_minus_1 < 64, "");
 
-    auto r = umul192_lower128(two_f, cache);
-    return {((r.high() >> (64 - beta)) & 1) != 0,
-            ((r.high() << beta) | (r.low() >> (64 - beta))) == 0};
+    return ((umul192_middle64(two_f, cache) >> (64 - beta_minus_1)) & 1) != 0;
   }
 
   static carrier_uint compute_left_endpoint_for_shorter_interval_case(
-      const cache_entry_type& cache, int beta) noexcept {
+      const cache_entry_type& cache, int beta_minus_1) FMT_NOEXCEPT {
     return (cache.high() -
-            (cache.high() >> (num_significand_bits<double>() + 2))) >>
-           (64 - num_significand_bits<double>() - 1 - beta);
+            (cache.high() >> (float_info<double>::significand_bits + 2))) >>
+           (64 - float_info<double>::significand_bits - 1 - beta_minus_1);
   }
 
   static carrier_uint compute_right_endpoint_for_shorter_interval_case(
-      const cache_entry_type& cache, int beta) noexcept {
+      const cache_entry_type& cache, int beta_minus_1) FMT_NOEXCEPT {
     return (cache.high() +
-            (cache.high() >> (num_significand_bits<double>() + 1))) >>
-           (64 - num_significand_bits<double>() - 1 - beta);
+            (cache.high() >> (float_info<double>::significand_bits + 1))) >>
+           (64 - float_info<double>::significand_bits - 1 - beta_minus_1);
   }
 
   static carrier_uint compute_round_up_for_shorter_interval_case(
-      const cache_entry_type& cache, int beta) noexcept {
-    return ((cache.high() >> (64 - num_significand_bits<double>() - 2 - beta)) +
+      const cache_entry_type& cache, int beta_minus_1) FMT_NOEXCEPT {
+    return ((cache.high() >>
+             (64 - float_info<double>::significand_bits - 2 - beta_minus_1)) +
             1) /
            2;
   }
 };
 
-FMT_FUNC uint128_fallback get_cached_power(int k) noexcept {
-  return cache_accessor<double>::get_cached_power(k);
+// Various integer checks
+template <class T>
+bool is_left_endpoint_integer_shorter_interval(int exponent) FMT_NOEXCEPT {
+  return exponent >=
+             float_info<
+                 T>::case_shorter_interval_left_endpoint_lower_threshold &&
+         exponent <=
+             float_info<T>::case_shorter_interval_left_endpoint_upper_threshold;
+}
+template <class T>
+bool is_endpoint_integer(typename float_info<T>::carrier_uint two_f,
+                         int exponent, int minus_k) FMT_NOEXCEPT {
+  if (exponent < float_info<T>::case_fc_pm_half_lower_threshold) return false;
+  // For k >= 0.
+  if (exponent <= float_info<T>::case_fc_pm_half_upper_threshold) return true;
+  // For k < 0.
+  if (exponent > float_info<T>::divisibility_check_by_5_threshold) return false;
+  return divisible_by_power_of_5(two_f, minus_k);
 }
 
-// Various integer checks
-template <typename T>
-bool is_left_endpoint_integer_shorter_interval(int exponent) noexcept {
-  const int case_shorter_interval_left_endpoint_lower_threshold = 2;
-  const int case_shorter_interval_left_endpoint_upper_threshold = 3;
-  return exponent >= case_shorter_interval_left_endpoint_lower_threshold &&
-         exponent <= case_shorter_interval_left_endpoint_upper_threshold;
+template <class T>
+bool is_center_integer(typename float_info<T>::carrier_uint two_f, int exponent,
+                       int minus_k) FMT_NOEXCEPT {
+  // Exponent for 5 is negative.
+  if (exponent > float_info<T>::divisibility_check_by_5_threshold) return false;
+  if (exponent > float_info<T>::case_fc_upper_threshold)
+    return divisible_by_power_of_5(two_f, minus_k);
+  // Both exponents are nonnegative.
+  if (exponent >= float_info<T>::case_fc_lower_threshold) return true;
+  // Exponent for 2 is negative.
+  return divisible_by_power_of_2(two_f, minus_k - exponent + 1);
 }
 
 // Remove trailing zeros from n and return the number of zeros removed (float)
-FMT_INLINE int remove_trailing_zeros(uint32_t& n, int s = 0) noexcept {
-  FMT_ASSERT(n != 0, "");
-  // Modular inverse of 5 (mod 2^32): (mod_inv_5 * 5) mod 2^32 = 1.
-  constexpr uint32_t mod_inv_5 = 0xcccccccd;
-  constexpr uint32_t mod_inv_25 = 0xc28f5c29;  // = mod_inv_5 * mod_inv_5
-
-  while (true) {
-    auto q = rotr(n * mod_inv_25, 2);
-    if (q > max_value<uint32_t>() / 100) break;
-    n = q;
-    s += 2;
-  }
-  auto q = rotr(n * mod_inv_5, 1);
-  if (q <= max_value<uint32_t>() / 10) {
-    n = q;
-    s |= 1;
+FMT_ALWAYS_INLINE int remove_trailing_zeros(uint32_t& n) FMT_NOEXCEPT {
+#ifdef FMT_BUILTIN_CTZ
+  int t = FMT_BUILTIN_CTZ(n);
+#else
+  int t = ctz(n);
+#endif
+  if (t > float_info<float>::max_trailing_zeros)
+    t = float_info<float>::max_trailing_zeros;
+
+  const uint32_t mod_inv1 = 0xcccccccd;
+  const uint32_t max_quotient1 = 0x33333333;
+  const uint32_t mod_inv2 = 0xc28f5c29;
+  const uint32_t max_quotient2 = 0x0a3d70a3;
+
+  int s = 0;
+  for (; s < t - 1; s += 2) {
+    if (n * mod_inv2 > max_quotient2) break;
+    n *= mod_inv2;
+  }
+  if (s < t && n * mod_inv1 <= max_quotient1) {
+    n *= mod_inv1;
+    ++s;
   }
+  n >>= s;
   return s;
 }
 
 // Removes trailing zeros and returns the number of zeros removed (double)
-FMT_INLINE int remove_trailing_zeros(uint64_t& n) noexcept {
-  FMT_ASSERT(n != 0, "");
+FMT_ALWAYS_INLINE int remove_trailing_zeros(uint64_t& n) FMT_NOEXCEPT {
+#ifdef FMT_BUILTIN_CTZLL
+  int t = FMT_BUILTIN_CTZLL(n);
+#else
+  int t = ctzll(n);
+#endif
+  if (t > float_info<double>::max_trailing_zeros)
+    t = float_info<double>::max_trailing_zeros;
+  // Divide by 10^8 and reduce to 32-bits
+  // Since ret_value.significand <= (2^64 - 1) / 1000 < 10^17,
+  // both of the quotient and the r should fit in 32-bits
+
+  const uint32_t mod_inv1 = 0xcccccccd;
+  const uint32_t max_quotient1 = 0x33333333;
+  const uint64_t mod_inv8 = 0xc767074b22e90e21;
+  const uint64_t max_quotient8 = 0x00002af31dc46118;
+
+  // If the number is divisible by 1'0000'0000, work with the quotient
+  if (t >= 8) {
+    auto quotient_candidate = n * mod_inv8;
+
+    if (quotient_candidate <= max_quotient8) {
+      auto quotient = static_cast<uint32_t>(quotient_candidate >> 8);
+
+      int s = 8;
+      for (; s < t; ++s) {
+        if (quotient * mod_inv1 > max_quotient1) break;
+        quotient *= mod_inv1;
+      }
+      quotient >>= (s - 8);
+      n = quotient;
+      return s;
+    }
+  }
 
-  // This magic number is ceil(2^90 / 10^8).
-  constexpr uint64_t magic_number = 12379400392853802749ull;
-  auto nm = umul128(n, magic_number);
+  // Otherwise, work with the remainder
+  auto quotient = static_cast<uint32_t>(n / 100000000);
+  auto remainder = static_cast<uint32_t>(n - 100000000 * quotient);
 
-  // Is n is divisible by 10^8?
-  if ((nm.high() & ((1ull << (90 - 64)) - 1)) == 0 && nm.low() < magic_number) {
-    // If yes, work with the quotient...
-    auto n32 = static_cast<uint32_t>(nm.high() >> (90 - 64));
-    // ... and use the 32 bit variant of the function
-    int s = remove_trailing_zeros(n32, 8);
-    n = n32;
-    return s;
+  if (t == 0 || remainder * mod_inv1 > max_quotient1) {
+    return 0;
   }
+  remainder *= mod_inv1;
 
-  // If n is not divisible by 10^8, work with n itself.
-  constexpr uint64_t mod_inv_5 = 0xcccccccccccccccd;
-  constexpr uint64_t mod_inv_25 = 0x8f5c28f5c28f5c29;  // mod_inv_5 * mod_inv_5
+  if (t == 1 || remainder * mod_inv1 > max_quotient1) {
+    n = (remainder >> 1) + quotient * 10000000ull;
+    return 1;
+  }
+  remainder *= mod_inv1;
 
-  int s = 0;
-  while (true) {
-    auto q = rotr(n * mod_inv_25, 2);
-    if (q > max_value<uint64_t>() / 100) break;
-    n = q;
-    s += 2;
+  if (t == 2 || remainder * mod_inv1 > max_quotient1) {
+    n = (remainder >> 2) + quotient * 1000000ull;
+    return 2;
   }
-  auto q = rotr(n * mod_inv_5, 1);
-  if (q <= max_value<uint64_t>() / 10) {
-    n = q;
-    s |= 1;
+  remainder *= mod_inv1;
+
+  if (t == 3 || remainder * mod_inv1 > max_quotient1) {
+    n = (remainder >> 3) + quotient * 100000ull;
+    return 3;
   }
+  remainder *= mod_inv1;
 
-  return s;
+  if (t == 4 || remainder * mod_inv1 > max_quotient1) {
+    n = (remainder >> 4) + quotient * 10000ull;
+    return 4;
+  }
+  remainder *= mod_inv1;
+
+  if (t == 5 || remainder * mod_inv1 > max_quotient1) {
+    n = (remainder >> 5) + quotient * 1000ull;
+    return 5;
+  }
+  remainder *= mod_inv1;
+
+  if (t == 6 || remainder * mod_inv1 > max_quotient1) {
+    n = (remainder >> 6) + quotient * 100ull;
+    return 6;
+  }
+  remainder *= mod_inv1;
+
+  n = (remainder >> 7) + quotient * 10ull;
+  return 7;
 }
 
 // The main algorithm for shorter interval case
-template <typename T>
-FMT_INLINE decimal_fp<T> shorter_interval_case(int exponent) noexcept {
+template <class T>
+FMT_ALWAYS_INLINE FMT_SAFEBUFFERS decimal_fp<T> shorter_interval_case(
+    int exponent) FMT_NOEXCEPT {
   decimal_fp<T> ret_value;
   // Compute k and beta
   const int minus_k = floor_log10_pow2_minus_log10_4_over_3(exponent);
-  const int beta = exponent + floor_log2_pow10(-minus_k);
+  const int beta_minus_1 = exponent + floor_log2_pow10(-minus_k);
 
   // Compute xi and zi
   using cache_entry_type = typename cache_accessor<T>::cache_entry_type;
   const cache_entry_type cache = cache_accessor<T>::get_cached_power(-minus_k);
 
   auto xi = cache_accessor<T>::compute_left_endpoint_for_shorter_interval_case(
-      cache, beta);
+      cache, beta_minus_1);
   auto zi = cache_accessor<T>::compute_right_endpoint_for_shorter_interval_case(
-      cache, beta);
+      cache, beta_minus_1);
 
   // If the left endpoint is not an integer, increase it
   if (!is_left_endpoint_integer_shorter_interval<T>(exponent)) ++xi;
@@ -1216,8 +2155,8 @@ FMT_INLINE decimal_fp<T> shorter_interval_case(int exponent) noexcept {
 
   // Otherwise, compute the round-up of y
   ret_value.significand =
-      cache_accessor<T>::compute_round_up_for_shorter_interval_case(cache,
-                                                                    beta);
+      cache_accessor<T>::compute_round_up_for_shorter_interval_case(
+          cache, beta_minus_1);
   ret_value.exponent = minus_k;
 
   // When tie occurs, choose one of them according to the rule
@@ -1232,7 +2171,8 @@ FMT_INLINE decimal_fp<T> shorter_interval_case(int exponent) noexcept {
   return ret_value;
 }
 
-template <typename T> decimal_fp<T> to_decimal(T x) noexcept {
+template <typename T>
+FMT_SAFEBUFFERS decimal_fp<T> to_decimal(T x) FMT_NOEXCEPT {
   // Step 1: integer promotion & Schubfach multiplier calculation.
 
   using carrier_uint = typename float_info<T>::carrier_uint;
@@ -1241,25 +2181,23 @@ template <typename T> decimal_fp<T> to_decimal(T x) noexcept {
 
   // Extract significand bits and exponent bits.
   const carrier_uint significand_mask =
-      (static_cast<carrier_uint>(1) << num_significand_bits<T>()) - 1;
+      (static_cast<carrier_uint>(1) << float_info<T>::significand_bits) - 1;
   carrier_uint significand = (br & significand_mask);
-  int exponent =
-      static_cast<int>((br & exponent_mask<T>()) >> num_significand_bits<T>());
+  int exponent = static_cast<int>((br & exponent_mask<T>()) >>
+                                  float_info<T>::significand_bits);
 
   if (exponent != 0) {  // Check if normal.
-    exponent -= exponent_bias<T>() + num_significand_bits<T>();
+    exponent += float_info<T>::exponent_bias - float_info<T>::significand_bits;
 
     // Shorter interval case; proceed like Schubfach.
-    // In fact, when exponent == 1 and significand == 0, the interval is
-    // regular. However, it can be shown that the end-results are anyway same.
     if (significand == 0) return shorter_interval_case<T>(exponent);
 
-    significand |= (static_cast<carrier_uint>(1) << num_significand_bits<T>());
+    significand |=
+        (static_cast<carrier_uint>(1) << float_info<T>::significand_bits);
   } else {
     // Subnormal case; the interval is always regular.
     if (significand == 0) return {0, 0};
-    exponent =
-        std::numeric_limits<T>::min_exponent - num_significand_bits<T>() - 1;
+    exponent = float_info<T>::min_exponent - float_info<T>::significand_bits;
   }
 
   const bool include_left_endpoint = (significand % 2 == 0);
@@ -1268,125 +2206,485 @@ template <typename T> decimal_fp<T> to_decimal(T x) noexcept {
   // Compute k and beta.
   const int minus_k = floor_log10_pow2(exponent) - float_info<T>::kappa;
   const cache_entry_type cache = cache_accessor<T>::get_cached_power(-minus_k);
-  const int beta = exponent + floor_log2_pow10(-minus_k);
+  const int beta_minus_1 = exponent + floor_log2_pow10(-minus_k);
 
-  // Compute zi and deltai.
+  // Compute zi and deltai
   // 10^kappa <= deltai < 10^(kappa + 1)
-  const uint32_t deltai = cache_accessor<T>::compute_delta(cache, beta);
+  const uint32_t deltai = cache_accessor<T>::compute_delta(cache, beta_minus_1);
   const carrier_uint two_fc = significand << 1;
+  const carrier_uint two_fr = two_fc | 1;
+  const carrier_uint zi =
+      cache_accessor<T>::compute_mul(two_fr << beta_minus_1, cache);
 
-  // For the case of binary32, the result of integer check is not correct for
-  // 29711844 * 2^-82
-  // = 6.1442653300000000008655037797566933477355632930994033813476... * 10^-18
-  // and 29711844 * 2^-81
-  // = 1.2288530660000000001731007559513386695471126586198806762695... * 10^-17,
-  // and they are the unique counterexamples. However, since 29711844 is even,
-  // this does not cause any problem for the endpoints calculations; it can only
-  // cause a problem when we need to perform integer check for the center.
-  // Fortunately, with these inputs, that branch is never executed, so we are
-  // fine.
-  const typename cache_accessor<T>::compute_mul_result z_mul =
-      cache_accessor<T>::compute_mul((two_fc | 1) << beta, cache);
-
-  // Step 2: Try larger divisor; remove trailing zeros if necessary.
+  // Step 2: Try larger divisor; remove trailing zeros if necessary
 
   // Using an upper bound on zi, we might be able to optimize the division
-  // better than the compiler; we are computing zi / big_divisor here.
+  // better than the compiler; we are computing zi / big_divisor here
   decimal_fp<T> ret_value;
-  ret_value.significand = divide_by_10_to_kappa_plus_1(z_mul.result);
-  uint32_t r = static_cast<uint32_t>(z_mul.result - float_info<T>::big_divisor *
-                                                        ret_value.significand);
+  ret_value.significand = divide_by_10_to_kappa_plus_1(zi);
+  uint32_t r = static_cast<uint32_t>(zi - float_info<T>::big_divisor *
+                                              ret_value.significand);
 
-  if (r < deltai) {
-    // Exclude the right endpoint if necessary.
-    if (r == 0 && (z_mul.is_integer & !include_right_endpoint)) {
+  if (r > deltai) {
+    goto small_divisor_case_label;
+  } else if (r < deltai) {
+    // Exclude the right endpoint if necessary
+    if (r == 0 && !include_right_endpoint &&
+        is_endpoint_integer<T>(two_fr, exponent, minus_k)) {
       --ret_value.significand;
       r = float_info<T>::big_divisor;
       goto small_divisor_case_label;
     }
-  } else if (r > deltai) {
-    goto small_divisor_case_label;
   } else {
-    // r == deltai; compare fractional parts.
-    const typename cache_accessor<T>::compute_mul_parity_result x_mul =
-        cache_accessor<T>::compute_mul_parity(two_fc - 1, cache, beta);
-
-    if (!(x_mul.parity | (x_mul.is_integer & include_left_endpoint)))
+    // r == deltai; compare fractional parts
+    // Check conditions in the order different from the paper
+    // to take advantage of short-circuiting
+    const carrier_uint two_fl = two_fc - 1;
+    if ((!include_left_endpoint ||
+         !is_endpoint_integer<T>(two_fl, exponent, minus_k)) &&
+        !cache_accessor<T>::compute_mul_parity(two_fl, cache, beta_minus_1)) {
       goto small_divisor_case_label;
+    }
   }
   ret_value.exponent = minus_k + float_info<T>::kappa + 1;
 
-  // We may need to remove trailing zeros.
+  // We may need to remove trailing zeros
   ret_value.exponent += remove_trailing_zeros(ret_value.significand);
   return ret_value;
 
-  // Step 3: Find the significand with the smaller divisor.
+  // Step 3: Find the significand with the smaller divisor
 
 small_divisor_case_label:
   ret_value.significand *= 10;
   ret_value.exponent = minus_k + float_info<T>::kappa;
 
-  uint32_t dist = r - (deltai / 2) + (float_info<T>::small_divisor / 2);
-  const bool approx_y_parity =
-      ((dist ^ (float_info<T>::small_divisor / 2)) & 1) != 0;
-
-  // Is dist divisible by 10^kappa?
-  const bool divisible_by_small_divisor =
-      check_divisibility_and_divide_by_pow10<float_info<T>::kappa>(dist);
-
-  // Add dist / 10^kappa to the significand.
-  ret_value.significand += dist;
-
-  if (!divisible_by_small_divisor) return ret_value;
-
-  // Check z^(f) >= epsilon^(f).
-  // We have either yi == zi - epsiloni or yi == (zi - epsiloni) - 1,
-  // where yi == zi - epsiloni if and only if z^(f) >= epsilon^(f).
-  // Since there are only 2 possibilities, we only need to care about the
-  // parity. Also, zi and r should have the same parity since the divisor
-  // is an even number.
-  const auto y_mul = cache_accessor<T>::compute_mul_parity(two_fc, cache, beta);
-
-  // If z^(f) >= epsilon^(f), we might have a tie when z^(f) == epsilon^(f),
-  // or equivalently, when y is an integer.
-  if (y_mul.parity != approx_y_parity)
-    --ret_value.significand;
-  else if (y_mul.is_integer & (ret_value.significand % 2 != 0))
-    --ret_value.significand;
+  const uint32_t mask = (1u << float_info<T>::kappa) - 1;
+  auto dist = r - (deltai / 2) + (float_info<T>::small_divisor / 2);
+
+  // Is dist divisible by 2^kappa?
+  if ((dist & mask) == 0) {
+    const bool approx_y_parity =
+        ((dist ^ (float_info<T>::small_divisor / 2)) & 1) != 0;
+    dist >>= float_info<T>::kappa;
+
+    // Is dist divisible by 5^kappa?
+    if (check_divisibility_and_divide_by_pow5<float_info<T>::kappa>(dist)) {
+      ret_value.significand += dist;
+
+      // Check z^(f) >= epsilon^(f)
+      // We have either yi == zi - epsiloni or yi == (zi - epsiloni) - 1,
+      // where yi == zi - epsiloni if and only if z^(f) >= epsilon^(f)
+      // Since there are only 2 possibilities, we only need to care about the
+      // parity. Also, zi and r should have the same parity since the divisor
+      // is an even number
+      if (cache_accessor<T>::compute_mul_parity(two_fc, cache, beta_minus_1) !=
+          approx_y_parity) {
+        --ret_value.significand;
+      } else {
+        // If z^(f) >= epsilon^(f), we might have a tie
+        // when z^(f) == epsilon^(f), or equivalently, when y is an integer
+        if (is_center_integer<T>(two_fc, exponent, minus_k)) {
+          ret_value.significand = ret_value.significand % 2 == 0
+                                      ? ret_value.significand
+                                      : ret_value.significand - 1;
+        }
+      }
+    }
+    // Is dist not divisible by 5^kappa?
+    else {
+      ret_value.significand += dist;
+    }
+  }
+  // Is dist not divisible by 2^kappa?
+  else {
+    // Since we know dist is small, we might be able to optimize the division
+    // better than the compiler; we are computing dist / small_divisor here
+    ret_value.significand +=
+        small_division_by_pow10<float_info<T>::kappa>(dist);
+  }
   return ret_value;
 }
 }  // namespace dragonbox
+
+// Formats value using a variation of the Fixed-Precision Positive
+// Floating-Point Printout ((FPP)^2) algorithm by Steele & White:
+// https://fmt.dev/p372-steele.pdf.
+template <typename Double>
+void fallback_format(Double d, int num_digits, bool binary32, buffer<char>& buf,
+                     int& exp10) {
+  bigint numerator;    // 2 * R in (FPP)^2.
+  bigint denominator;  // 2 * S in (FPP)^2.
+  // lower and upper are differences between value and corresponding boundaries.
+  bigint lower;             // (M^- in (FPP)^2).
+  bigint upper_store;       // upper's value if different from lower.
+  bigint* upper = nullptr;  // (M^+ in (FPP)^2).
+  fp value;
+  // Shift numerator and denominator by an extra bit or two (if lower boundary
+  // is closer) to make lower and upper integers. This eliminates multiplication
+  // by 2 during later computations.
+  const bool is_predecessor_closer =
+      binary32 ? value.assign(static_cast<float>(d)) : value.assign(d);
+  int shift = is_predecessor_closer ? 2 : 1;
+  uint64_t significand = value.f << shift;
+  if (value.e >= 0) {
+    numerator.assign(significand);
+    numerator <<= value.e;
+    lower.assign(1);
+    lower <<= value.e;
+    if (shift != 1) {
+      upper_store.assign(1);
+      upper_store <<= value.e + 1;
+      upper = &upper_store;
+    }
+    denominator.assign_pow10(exp10);
+    denominator <<= shift;
+  } else if (exp10 < 0) {
+    numerator.assign_pow10(-exp10);
+    lower.assign(numerator);
+    if (shift != 1) {
+      upper_store.assign(numerator);
+      upper_store <<= 1;
+      upper = &upper_store;
+    }
+    numerator *= significand;
+    denominator.assign(1);
+    denominator <<= shift - value.e;
+  } else {
+    numerator.assign(significand);
+    denominator.assign_pow10(exp10);
+    denominator <<= shift - value.e;
+    lower.assign(1);
+    if (shift != 1) {
+      upper_store.assign(1ULL << 1);
+      upper = &upper_store;
+    }
+  }
+  // Invariant: value == (numerator / denominator) * pow(10, exp10).
+  if (num_digits < 0) {
+    // Generate the shortest representation.
+    if (!upper) upper = &lower;
+    bool even = (value.f & 1) == 0;
+    num_digits = 0;
+    char* data = buf.data();
+    for (;;) {
+      int digit = numerator.divmod_assign(denominator);
+      bool low = compare(numerator, lower) - even < 0;  // numerator <[=] lower.
+      // numerator + upper >[=] pow10:
+      bool high = add_compare(numerator, *upper, denominator) + even > 0;
+      data[num_digits++] = static_cast<char>('0' + digit);
+      if (low || high) {
+        if (!low) {
+          ++data[num_digits - 1];
+        } else if (high) {
+          int result = add_compare(numerator, numerator, denominator);
+          // Round half to even.
+          if (result > 0 || (result == 0 && (digit % 2) != 0))
+            ++data[num_digits - 1];
+        }
+        buf.try_resize(to_unsigned(num_digits));
+        exp10 -= num_digits - 1;
+        return;
+      }
+      numerator *= 10;
+      lower *= 10;
+      if (upper != &lower) *upper *= 10;
+    }
+  }
+  // Generate the given number of digits.
+  exp10 -= num_digits - 1;
+  if (num_digits == 0) {
+    buf.try_resize(1);
+    denominator *= 10;
+    buf[0] = add_compare(numerator, numerator, denominator) > 0 ? '1' : '0';
+    return;
+  }
+  buf.try_resize(to_unsigned(num_digits));
+  for (int i = 0; i < num_digits - 1; ++i) {
+    int digit = numerator.divmod_assign(denominator);
+    buf[i] = static_cast<char>('0' + digit);
+    numerator *= 10;
+  }
+  int digit = numerator.divmod_assign(denominator);
+  auto result = add_compare(numerator, numerator, denominator);
+  if (result > 0 || (result == 0 && (digit % 2) != 0)) {
+    if (digit == 9) {
+      const auto overflow = '0' + 10;
+      buf[num_digits - 1] = overflow;
+      // Propagate the carry.
+      for (int i = num_digits - 1; i > 0 && buf[i] == overflow; --i) {
+        buf[i] = '0';
+        ++buf[i - 1];
+      }
+      if (buf[0] == overflow) {
+        buf[0] = '1';
+        ++exp10;
+      }
+      return;
+    }
+    ++digit;
+  }
+  buf[num_digits - 1] = static_cast<char>('0' + digit);
+}
+
+template <typename T>
+int format_float(T value, int precision, float_specs specs, buffer<char>& buf) {
+  static_assert(!std::is_same<T, float>::value, "");
+  FMT_ASSERT(value >= 0, "value is negative");
+
+  const bool fixed = specs.format == float_format::fixed;
+  if (value <= 0) {  // <= instead of == to silence a warning.
+    if (precision <= 0 || !fixed) {
+      buf.push_back('0');
+      return 0;
+    }
+    buf.try_resize(to_unsigned(precision));
+    std::uninitialized_fill_n(buf.data(), precision, '0');
+    return -precision;
+  }
+
+  if (!specs.use_grisu) return snprintf_float(value, precision, specs, buf);
+
+  if (precision < 0) {
+    // Use Dragonbox for the shortest format.
+    if (specs.binary32) {
+      auto dec = dragonbox::to_decimal(static_cast<float>(value));
+      write<char>(buffer_appender<char>(buf), dec.significand);
+      return dec.exponent;
+    }
+    auto dec = dragonbox::to_decimal(static_cast<double>(value));
+    write<char>(buffer_appender<char>(buf), dec.significand);
+    return dec.exponent;
+  }
+
+  // Use Grisu + Dragon4 for the given precision:
+  // https://www.cs.tufts.edu/~nr/cs257/archive/florian-loitsch/printf.pdf.
+  int exp = 0;
+  const int min_exp = -60;  // alpha in Grisu.
+  int cached_exp10 = 0;     // K in Grisu.
+  fp normalized = normalize(fp(value));
+  const auto cached_pow = get_cached_power(
+      min_exp - (normalized.e + fp::significand_size), cached_exp10);
+  normalized = normalized * cached_pow;
+  // Limit precision to the maximum possible number of significant digits in an
+  // IEEE754 double because we don't need to generate zeros.
+  const int max_double_digits = 767;
+  if (precision > max_double_digits) precision = max_double_digits;
+  fixed_handler handler{buf.data(), 0, precision, -cached_exp10, fixed};
+  if (grisu_gen_digits(normalized, 1, exp, handler) == digits::error) {
+    exp += handler.size - cached_exp10 - 1;
+    fallback_format(value, handler.precision, specs.binary32, buf, exp);
+  } else {
+    exp += handler.exp10;
+    buf.try_resize(to_unsigned(handler.size));
+  }
+  if (!fixed && !specs.showpoint) {
+    // Remove trailing zeros.
+    auto num_digits = buf.size();
+    while (num_digits > 0 && buf[num_digits - 1] == '0') {
+      --num_digits;
+      ++exp;
+    }
+    buf.try_resize(num_digits);
+  }
+  return exp;
+}  // namespace detail
+
+template <typename T>
+int snprintf_float(T value, int precision, float_specs specs,
+                   buffer<char>& buf) {
+  // Buffer capacity must be non-zero, otherwise MSVC's vsnprintf_s will fail.
+  FMT_ASSERT(buf.capacity() > buf.size(), "empty buffer");
+  static_assert(!std::is_same<T, float>::value, "");
+
+  // Subtract 1 to account for the difference in precision since we use %e for
+  // both general and exponent format.
+  if (specs.format == float_format::general ||
+      specs.format == float_format::exp)
+    precision = (precision >= 0 ? precision : 6) - 1;
+
+  // Build the format string.
+  enum { max_format_size = 7 };  // The longest format is "%#.*Le".
+  char format[max_format_size];
+  char* format_ptr = format;
+  *format_ptr++ = '%';
+  if (specs.showpoint && specs.format == float_format::hex) *format_ptr++ = '#';
+  if (precision >= 0) {
+    *format_ptr++ = '.';
+    *format_ptr++ = '*';
+  }
+  if (std::is_same<T, long double>()) *format_ptr++ = 'L';
+  *format_ptr++ = specs.format != float_format::hex
+                      ? (specs.format == float_format::fixed ? 'f' : 'e')
+                      : (specs.upper ? 'A' : 'a');
+  *format_ptr = '\0';
+
+  // Format using snprintf.
+  auto offset = buf.size();
+  for (;;) {
+    auto begin = buf.data() + offset;
+    auto capacity = buf.capacity() - offset;
+#ifdef FMT_FUZZ
+    if (precision > 100000)
+      throw std::runtime_error(
+          "fuzz mode - avoid large allocation inside snprintf");
+#endif
+    // Suppress the warning about a nonliteral format string.
+    // Cannot use auto because of a bug in MinGW (#1532).
+    int (*snprintf_ptr)(char*, size_t, const char*, ...) = FMT_SNPRINTF;
+    int result = precision >= 0
+                     ? snprintf_ptr(begin, capacity, format, precision, value)
+                     : snprintf_ptr(begin, capacity, format, value);
+    if (result < 0) {
+      // The buffer will grow exponentially.
+      buf.try_reserve(buf.capacity() + 1);
+      continue;
+    }
+    auto size = to_unsigned(result);
+    // Size equal to capacity means that the last character was truncated.
+    if (size >= capacity) {
+      buf.try_reserve(size + offset + 1);  // Add 1 for the terminating '\0'.
+      continue;
+    }
+    auto is_digit = [](char c) { return c >= '0' && c <= '9'; };
+    if (specs.format == float_format::fixed) {
+      if (precision == 0) {
+        buf.try_resize(size);
+        return 0;
+      }
+      // Find and remove the decimal point.
+      auto end = begin + size, p = end;
+      do {
+        --p;
+      } while (is_digit(*p));
+      int fraction_size = static_cast<int>(end - p - 1);
+      std::memmove(p, p + 1, to_unsigned(fraction_size));
+      buf.try_resize(size - 1);
+      return -fraction_size;
+    }
+    if (specs.format == float_format::hex) {
+      buf.try_resize(size + offset);
+      return 0;
+    }
+    // Find and parse the exponent.
+    auto end = begin + size, exp_pos = end;
+    do {
+      --exp_pos;
+    } while (*exp_pos != 'e');
+    char sign = exp_pos[1];
+    assert(sign == '+' || sign == '-');
+    int exp = 0;
+    auto p = exp_pos + 2;  // Skip 'e' and sign.
+    do {
+      assert(is_digit(*p));
+      exp = exp * 10 + (*p++ - '0');
+    } while (p != end);
+    if (sign == '-') exp = -exp;
+    int fraction_size = 0;
+    if (exp_pos != begin + 1) {
+      // Remove trailing zeros.
+      auto fraction_end = exp_pos - 1;
+      while (*fraction_end == '0') --fraction_end;
+      // Move the fractional part left to get rid of the decimal point.
+      fraction_size = static_cast<int>(fraction_end - begin - 1);
+      std::memmove(begin + 1, begin + 2, to_unsigned(fraction_size));
+    }
+    buf.try_resize(to_unsigned(fraction_size) + offset + 1);
+    return exp - fraction_size;
+  }
+}
+
+// A public domain branchless UTF-8 decoder by Christopher Wellons:
+// https://github.com/skeeto/branchless-utf8
+/* Decode the next character, c, from buf, reporting errors in e.
+ *
+ * Since this is a branchless decoder, four bytes will be read from the
+ * buffer regardless of the actual length of the next character. This
+ * means the buffer _must_ have at least three bytes of zero padding
+ * following the end of the data stream.
+ *
+ * Errors are reported in e, which will be non-zero if the parsed
+ * character was somehow invalid: invalid byte sequence, non-canonical
+ * encoding, or a surrogate half.
+ *
+ * The function returns a pointer to the next character. When an error
+ * occurs, this pointer will be a guess that depends on the particular
+ * error, but it will always advance at least one byte.
+ */
+inline const char* utf8_decode(const char* buf, uint32_t* c, int* e) {
+  static const int masks[] = {0x00, 0x7f, 0x1f, 0x0f, 0x07};
+  static const uint32_t mins[] = {4194304, 0, 128, 2048, 65536};
+  static const int shiftc[] = {0, 18, 12, 6, 0};
+  static const int shifte[] = {0, 6, 4, 2, 0};
+
+  int len = code_point_length(buf);
+  const char* next = buf + len;
+
+  // Assume a four-byte character and load four bytes. Unused bits are
+  // shifted out.
+  auto s = reinterpret_cast<const unsigned char*>(buf);
+  *c = uint32_t(s[0] & masks[len]) << 18;
+  *c |= uint32_t(s[1] & 0x3f) << 12;
+  *c |= uint32_t(s[2] & 0x3f) << 6;
+  *c |= uint32_t(s[3] & 0x3f) << 0;
+  *c >>= shiftc[len];
+
+  // Accumulate the various error conditions.
+  *e = (*c < mins[len]) << 6;       // non-canonical encoding
+  *e |= ((*c >> 11) == 0x1b) << 7;  // surrogate half?
+  *e |= (*c > 0x10FFFF) << 8;       // out of range?
+  *e |= (s[1] & 0xc0) >> 2;
+  *e |= (s[2] & 0xc0) >> 4;
+  *e |= (s[3]) >> 6;
+  *e ^= 0x2a;  // top two bits of each tail byte correct?
+  *e >>= shifte[len];
+
+  return next;
+}
+
+struct stringifier {
+  template <typename T> FMT_INLINE std::string operator()(T value) const {
+    return to_string(value);
+  }
+  std::string operator()(basic_format_arg<format_context>::handle h) const {
+    memory_buffer buf;
+    format_parse_context parse_ctx({});
+    format_context format_ctx(buffer_appender<char>(buf), {}, {});
+    h.format(parse_ctx, format_ctx);
+    return to_string(buf);
+  }
+};
 }  // namespace detail
 
 template <> struct formatter<detail::bigint> {
-  FMT_CONSTEXPR auto parse(format_parse_context& ctx)
-      -> format_parse_context::iterator {
+  format_parse_context::iterator parse(format_parse_context& ctx) {
     return ctx.begin();
   }
 
-  auto format(const detail::bigint& n, format_context& ctx) const
-      -> format_context::iterator {
+  format_context::iterator format(const detail::bigint& n,
+                                  format_context& ctx) {
     auto out = ctx.out();
     bool first = true;
     for (auto i = n.bigits_.size(); i > 0; --i) {
       auto value = n.bigits_[i - 1u];
       if (first) {
-        out = format_to(out, FMT_STRING("{:x}"), value);
+        out = format_to(out, "{:x}", value);
         first = false;
         continue;
       }
-      out = format_to(out, FMT_STRING("{:08x}"), value);
+      out = format_to(out, "{:08x}", value);
     }
     if (n.exp_ > 0)
-      out = format_to(out, FMT_STRING("p{}"),
-                      n.exp_ * detail::bigint::bigit_bits);
+      out = format_to(out, "p{}", n.exp_ * detail::bigint::bigit_bits);
     return out;
   }
 };
 
 FMT_FUNC detail::utf8_to_utf16::utf8_to_utf16(string_view s) {
-  for_each_codepoint(s, [this](uint32_t cp, string_view) {
-    if (cp == invalid_code_point) FMT_THROW(std::runtime_error("invalid utf8"));
+  auto transcode = [this](const char* p) {
+    auto cp = uint32_t();
+    auto error = 0;
+    p = utf8_decode(p, &cp, &error);
+    if (error != 0) FMT_THROW(std::runtime_error("invalid utf8"));
     if (cp <= 0xFFFF) {
       buffer_.push_back(static_cast<wchar_t>(cp));
     } else {
@@ -1394,272 +2692,110 @@ FMT_FUNC detail::utf8_to_utf16::utf8_to_utf16(string_view s) {
       buffer_.push_back(static_cast<wchar_t>(0xD800 + (cp >> 10)));
       buffer_.push_back(static_cast<wchar_t>(0xDC00 + (cp & 0x3FF)));
     }
-    return true;
-  });
+    return p;
+  };
+  auto p = s.data();
+  const size_t block_size = 4;  // utf8_decode always reads blocks of 4 chars.
+  if (s.size() >= block_size) {
+    for (auto end = p + s.size() - block_size + 1; p < end;) p = transcode(p);
+  }
+  if (auto num_chars_left = s.data() + s.size() - p) {
+    char buf[2 * block_size - 1] = {};
+    memcpy(buf, p, to_unsigned(num_chars_left));
+    p = buf;
+    do {
+      p = transcode(p);
+    } while (p - buf < num_chars_left);
+  }
   buffer_.push_back(0);
 }
 
 FMT_FUNC void format_system_error(detail::buffer<char>& out, int error_code,
-                                  const char* message) noexcept {
+                                  string_view message) FMT_NOEXCEPT {
   FMT_TRY {
-    auto ec = std::error_code(error_code, std::generic_category());
-    write(std::back_inserter(out), std::system_error(ec, message).what());
-    return;
+    memory_buffer buf;
+    buf.resize(inline_buffer_size);
+    for (;;) {
+      char* system_message = &buf[0];
+      int result =
+          detail::safe_strerror(error_code, system_message, buf.size());
+      if (result == 0) {
+        format_to(detail::buffer_appender<char>(out), "{}: {}", message,
+                  system_message);
+        return;
+      }
+      if (result != ERANGE)
+        break;  // Can't get error message, report error code instead.
+      buf.resize(buf.size() * 2);
+    }
   }
   FMT_CATCH(...) {}
   format_error_code(out, error_code, message);
 }
 
+FMT_FUNC void detail::error_handler::on_error(const char* message) {
+  FMT_THROW(format_error(message));
+}
+
 FMT_FUNC void report_system_error(int error_code,
-                                  const char* message) noexcept {
+                                  fmt::string_view message) FMT_NOEXCEPT {
   report_error(format_system_error, error_code, message);
 }
 
-FMT_FUNC std::string vformat(string_view fmt, format_args args) {
-  // Don't optimize the "{}" case to keep the binary size small and because it
-  // can be better optimized in fmt::format anyway.
-  auto buffer = memory_buffer();
-  detail::vformat_to(buffer, fmt, args);
+FMT_FUNC std::string detail::vformat(string_view format_str, format_args args) {
+  if (format_str.size() == 2 && equal2(format_str.data(), "{}")) {
+    auto arg = args.get(0);
+    if (!arg) error_handler().on_error("argument not found");
+    return visit_format_arg(stringifier(), arg);
+  }
+  memory_buffer buffer;
+  detail::vformat_to(buffer, format_str, args);
   return to_string(buffer);
 }
 
+#ifdef _WIN32
 namespace detail {
-#if !defined(_WIN32) || defined(FMT_WINDOWS_NO_WCHAR)
-FMT_FUNC bool write_console(int, string_view) { return false; }
-#else
 using dword = conditional_t<sizeof(long) == 4, unsigned long, unsigned>;
 extern "C" __declspec(dllimport) int __stdcall WriteConsoleW(  //
     void*, const void*, dword, dword*, void*);
-
-FMT_FUNC bool write_console(int fd, string_view text) {
-  auto u16 = utf8_to_utf16(text);
-  return WriteConsoleW(reinterpret_cast<void*>(_get_osfhandle(fd)), u16.c_str(),
-                       static_cast<dword>(u16.size()), nullptr, nullptr) != 0;
-}
-#endif
-
-#ifdef _WIN32
-// Print assuming legacy (non-Unicode) encoding.
-FMT_FUNC void vprint_mojibake(std::FILE* f, string_view fmt, format_args args) {
-  auto buffer = memory_buffer();
-  detail::vformat_to(buffer, fmt, args);
-  fwrite_fully(buffer.data(), buffer.size(), f);
-}
+}  // namespace detail
 #endif
 
-FMT_FUNC void print(std::FILE* f, string_view text) {
+FMT_FUNC void vprint(std::FILE* f, string_view format_str, format_args args) {
+  memory_buffer buffer;
+  detail::vformat_to(buffer, format_str,
+                     basic_format_args<buffer_context<char>>(args));
 #ifdef _WIN32
-  int fd = _fileno(f);
+  auto fd = _fileno(f);
   if (_isatty(fd)) {
-    std::fflush(f);
-    if (write_console(fd, text)) return;
+    detail::utf8_to_utf16 u16(string_view(buffer.data(), buffer.size()));
+    auto written = detail::dword();
+    if (!detail::WriteConsoleW(reinterpret_cast<void*>(_get_osfhandle(fd)),
+                               u16.c_str(), static_cast<uint32_t>(u16.size()),
+                               &written, nullptr)) {
+      FMT_THROW(format_error("failed to write to console"));
+    }
+    return;
   }
 #endif
-  fwrite_fully(text.data(), text.size(), f);
-}
-}  // namespace detail
-
-FMT_FUNC void vprint(std::FILE* f, string_view fmt, format_args args) {
-  auto buffer = memory_buffer();
-  detail::vformat_to(buffer, fmt, args);
-  detail::print(f, {buffer.data(), buffer.size()});
-}
-
-FMT_FUNC void vprint(string_view fmt, format_args args) {
-  vprint(stdout, fmt, args);
+  detail::fwrite_fully(buffer.data(), 1, buffer.size(), f);
 }
 
-namespace detail {
-
-struct singleton {
-  unsigned char upper;
-  unsigned char lower_count;
-};
-
-inline auto is_printable(uint16_t x, const singleton* singletons,
-                         size_t singletons_size,
-                         const unsigned char* singleton_lowers,
-                         const unsigned char* normal, size_t normal_size)
-    -> bool {
-  auto upper = x >> 8;
-  auto lower_start = 0;
-  for (size_t i = 0; i < singletons_size; ++i) {
-    auto s = singletons[i];
-    auto lower_end = lower_start + s.lower_count;
-    if (upper < s.upper) break;
-    if (upper == s.upper) {
-      for (auto j = lower_start; j < lower_end; ++j) {
-        if (singleton_lowers[j] == (x & 0xff)) return false;
-      }
-    }
-    lower_start = lower_end;
-  }
-
-  auto xsigned = static_cast<int>(x);
-  auto current = true;
-  for (size_t i = 0; i < normal_size; ++i) {
-    auto v = static_cast<int>(normal[i]);
-    auto len = (v & 0x80) != 0 ? (v & 0x7f) << 8 | normal[++i] : v;
-    xsigned -= len;
-    if (xsigned < 0) break;
-    current = !current;
-  }
-  return current;
+#ifdef _WIN32
+// Print assuming legacy (non-Unicode) encoding.
+FMT_FUNC void detail::vprint_mojibake(std::FILE* f, string_view format_str,
+                                      format_args args) {
+  memory_buffer buffer;
+  detail::vformat_to(buffer, format_str,
+                     basic_format_args<buffer_context<char>>(args));
+  fwrite_fully(buffer.data(), 1, buffer.size(), f);
 }
+#endif
 
-// This code is generated by support/printable.py.
-FMT_FUNC auto is_printable(uint32_t cp) -> bool {
-  static constexpr singleton singletons0[] = {
-      {0x00, 1},  {0x03, 5},  {0x05, 6},  {0x06, 3},  {0x07, 6},  {0x08, 8},
-      {0x09, 17}, {0x0a, 28}, {0x0b, 25}, {0x0c, 20}, {0x0d, 16}, {0x0e, 13},
-      {0x0f, 4},  {0x10, 3},  {0x12, 18}, {0x13, 9},  {0x16, 1},  {0x17, 5},
-      {0x18, 2},  {0x19, 3},  {0x1a, 7},  {0x1c, 2},  {0x1d, 1},  {0x1f, 22},
-      {0x20, 3},  {0x2b, 3},  {0x2c, 2},  {0x2d, 11}, {0x2e, 1},  {0x30, 3},
-      {0x31, 2},  {0x32, 1},  {0xa7, 2},  {0xa9, 2},  {0xaa, 4},  {0xab, 8},
-      {0xfa, 2},  {0xfb, 5},  {0xfd, 4},  {0xfe, 3},  {0xff, 9},
-  };
-  static constexpr unsigned char singletons0_lower[] = {
-      0xad, 0x78, 0x79, 0x8b, 0x8d, 0xa2, 0x30, 0x57, 0x58, 0x8b, 0x8c, 0x90,
-      0x1c, 0x1d, 0xdd, 0x0e, 0x0f, 0x4b, 0x4c, 0xfb, 0xfc, 0x2e, 0x2f, 0x3f,
-      0x5c, 0x5d, 0x5f, 0xb5, 0xe2, 0x84, 0x8d, 0x8e, 0x91, 0x92, 0xa9, 0xb1,
-      0xba, 0xbb, 0xc5, 0xc6, 0xc9, 0xca, 0xde, 0xe4, 0xe5, 0xff, 0x00, 0x04,
-      0x11, 0x12, 0x29, 0x31, 0x34, 0x37, 0x3a, 0x3b, 0x3d, 0x49, 0x4a, 0x5d,
-      0x84, 0x8e, 0x92, 0xa9, 0xb1, 0xb4, 0xba, 0xbb, 0xc6, 0xca, 0xce, 0xcf,
-      0xe4, 0xe5, 0x00, 0x04, 0x0d, 0x0e, 0x11, 0x12, 0x29, 0x31, 0x34, 0x3a,
-      0x3b, 0x45, 0x46, 0x49, 0x4a, 0x5e, 0x64, 0x65, 0x84, 0x91, 0x9b, 0x9d,
-      0xc9, 0xce, 0xcf, 0x0d, 0x11, 0x29, 0x45, 0x49, 0x57, 0x64, 0x65, 0x8d,
-      0x91, 0xa9, 0xb4, 0xba, 0xbb, 0xc5, 0xc9, 0xdf, 0xe4, 0xe5, 0xf0, 0x0d,
-      0x11, 0x45, 0x49, 0x64, 0x65, 0x80, 0x84, 0xb2, 0xbc, 0xbe, 0xbf, 0xd5,
-      0xd7, 0xf0, 0xf1, 0x83, 0x85, 0x8b, 0xa4, 0xa6, 0xbe, 0xbf, 0xc5, 0xc7,
-      0xce, 0xcf, 0xda, 0xdb, 0x48, 0x98, 0xbd, 0xcd, 0xc6, 0xce, 0xcf, 0x49,
-      0x4e, 0x4f, 0x57, 0x59, 0x5e, 0x5f, 0x89, 0x8e, 0x8f, 0xb1, 0xb6, 0xb7,
-      0xbf, 0xc1, 0xc6, 0xc7, 0xd7, 0x11, 0x16, 0x17, 0x5b, 0x5c, 0xf6, 0xf7,
-      0xfe, 0xff, 0x80, 0x0d, 0x6d, 0x71, 0xde, 0xdf, 0x0e, 0x0f, 0x1f, 0x6e,
-      0x6f, 0x1c, 0x1d, 0x5f, 0x7d, 0x7e, 0xae, 0xaf, 0xbb, 0xbc, 0xfa, 0x16,
-      0x17, 0x1e, 0x1f, 0x46, 0x47, 0x4e, 0x4f, 0x58, 0x5a, 0x5c, 0x5e, 0x7e,
-      0x7f, 0xb5, 0xc5, 0xd4, 0xd5, 0xdc, 0xf0, 0xf1, 0xf5, 0x72, 0x73, 0x8f,
-      0x74, 0x75, 0x96, 0x2f, 0x5f, 0x26, 0x2e, 0x2f, 0xa7, 0xaf, 0xb7, 0xbf,
-      0xc7, 0xcf, 0xd7, 0xdf, 0x9a, 0x40, 0x97, 0x98, 0x30, 0x8f, 0x1f, 0xc0,
-      0xc1, 0xce, 0xff, 0x4e, 0x4f, 0x5a, 0x5b, 0x07, 0x08, 0x0f, 0x10, 0x27,
-      0x2f, 0xee, 0xef, 0x6e, 0x6f, 0x37, 0x3d, 0x3f, 0x42, 0x45, 0x90, 0x91,
-      0xfe, 0xff, 0x53, 0x67, 0x75, 0xc8, 0xc9, 0xd0, 0xd1, 0xd8, 0xd9, 0xe7,
-      0xfe, 0xff,
-  };
-  static constexpr singleton singletons1[] = {
-      {0x00, 6},  {0x01, 1}, {0x03, 1},  {0x04, 2}, {0x08, 8},  {0x09, 2},
-      {0x0a, 5},  {0x0b, 2}, {0x0e, 4},  {0x10, 1}, {0x11, 2},  {0x12, 5},
-      {0x13, 17}, {0x14, 1}, {0x15, 2},  {0x17, 2}, {0x19, 13}, {0x1c, 5},
-      {0x1d, 8},  {0x24, 1}, {0x6a, 3},  {0x6b, 2}, {0xbc, 2},  {0xd1, 2},
-      {0xd4, 12}, {0xd5, 9}, {0xd6, 2},  {0xd7, 2}, {0xda, 1},  {0xe0, 5},
-      {0xe1, 2},  {0xe8, 2}, {0xee, 32}, {0xf0, 4}, {0xf8, 2},  {0xf9, 2},
-      {0xfa, 2},  {0xfb, 1},
-  };
-  static constexpr unsigned char singletons1_lower[] = {
-      0x0c, 0x27, 0x3b, 0x3e, 0x4e, 0x4f, 0x8f, 0x9e, 0x9e, 0x9f, 0x06, 0x07,
-      0x09, 0x36, 0x3d, 0x3e, 0x56, 0xf3, 0xd0, 0xd1, 0x04, 0x14, 0x18, 0x36,
-      0x37, 0x56, 0x57, 0x7f, 0xaa, 0xae, 0xaf, 0xbd, 0x35, 0xe0, 0x12, 0x87,
-      0x89, 0x8e, 0x9e, 0x04, 0x0d, 0x0e, 0x11, 0x12, 0x29, 0x31, 0x34, 0x3a,
-      0x45, 0x46, 0x49, 0x4a, 0x4e, 0x4f, 0x64, 0x65, 0x5c, 0xb6, 0xb7, 0x1b,
-      0x1c, 0x07, 0x08, 0x0a, 0x0b, 0x14, 0x17, 0x36, 0x39, 0x3a, 0xa8, 0xa9,
-      0xd8, 0xd9, 0x09, 0x37, 0x90, 0x91, 0xa8, 0x07, 0x0a, 0x3b, 0x3e, 0x66,
-      0x69, 0x8f, 0x92, 0x6f, 0x5f, 0xee, 0xef, 0x5a, 0x62, 0x9a, 0x9b, 0x27,
-      0x28, 0x55, 0x9d, 0xa0, 0xa1, 0xa3, 0xa4, 0xa7, 0xa8, 0xad, 0xba, 0xbc,
-      0xc4, 0x06, 0x0b, 0x0c, 0x15, 0x1d, 0x3a, 0x3f, 0x45, 0x51, 0xa6, 0xa7,
-      0xcc, 0xcd, 0xa0, 0x07, 0x19, 0x1a, 0x22, 0x25, 0x3e, 0x3f, 0xc5, 0xc6,
-      0x04, 0x20, 0x23, 0x25, 0x26, 0x28, 0x33, 0x38, 0x3a, 0x48, 0x4a, 0x4c,
-      0x50, 0x53, 0x55, 0x56, 0x58, 0x5a, 0x5c, 0x5e, 0x60, 0x63, 0x65, 0x66,
-      0x6b, 0x73, 0x78, 0x7d, 0x7f, 0x8a, 0xa4, 0xaa, 0xaf, 0xb0, 0xc0, 0xd0,
-      0xae, 0xaf, 0x79, 0xcc, 0x6e, 0x6f, 0x93,
-  };
-  static constexpr unsigned char normal0[] = {
-      0x00, 0x20, 0x5f, 0x22, 0x82, 0xdf, 0x04, 0x82, 0x44, 0x08, 0x1b, 0x04,
-      0x06, 0x11, 0x81, 0xac, 0x0e, 0x80, 0xab, 0x35, 0x28, 0x0b, 0x80, 0xe0,
-      0x03, 0x19, 0x08, 0x01, 0x04, 0x2f, 0x04, 0x34, 0x04, 0x07, 0x03, 0x01,
-      0x07, 0x06, 0x07, 0x11, 0x0a, 0x50, 0x0f, 0x12, 0x07, 0x55, 0x07, 0x03,
-      0x04, 0x1c, 0x0a, 0x09, 0x03, 0x08, 0x03, 0x07, 0x03, 0x02, 0x03, 0x03,
-      0x03, 0x0c, 0x04, 0x05, 0x03, 0x0b, 0x06, 0x01, 0x0e, 0x15, 0x05, 0x3a,
-      0x03, 0x11, 0x07, 0x06, 0x05, 0x10, 0x07, 0x57, 0x07, 0x02, 0x07, 0x15,
-      0x0d, 0x50, 0x04, 0x43, 0x03, 0x2d, 0x03, 0x01, 0x04, 0x11, 0x06, 0x0f,
-      0x0c, 0x3a, 0x04, 0x1d, 0x25, 0x5f, 0x20, 0x6d, 0x04, 0x6a, 0x25, 0x80,
-      0xc8, 0x05, 0x82, 0xb0, 0x03, 0x1a, 0x06, 0x82, 0xfd, 0x03, 0x59, 0x07,
-      0x15, 0x0b, 0x17, 0x09, 0x14, 0x0c, 0x14, 0x0c, 0x6a, 0x06, 0x0a, 0x06,
-      0x1a, 0x06, 0x59, 0x07, 0x2b, 0x05, 0x46, 0x0a, 0x2c, 0x04, 0x0c, 0x04,
-      0x01, 0x03, 0x31, 0x0b, 0x2c, 0x04, 0x1a, 0x06, 0x0b, 0x03, 0x80, 0xac,
-      0x06, 0x0a, 0x06, 0x21, 0x3f, 0x4c, 0x04, 0x2d, 0x03, 0x74, 0x08, 0x3c,
-      0x03, 0x0f, 0x03, 0x3c, 0x07, 0x38, 0x08, 0x2b, 0x05, 0x82, 0xff, 0x11,
-      0x18, 0x08, 0x2f, 0x11, 0x2d, 0x03, 0x20, 0x10, 0x21, 0x0f, 0x80, 0x8c,
-      0x04, 0x82, 0x97, 0x19, 0x0b, 0x15, 0x88, 0x94, 0x05, 0x2f, 0x05, 0x3b,
-      0x07, 0x02, 0x0e, 0x18, 0x09, 0x80, 0xb3, 0x2d, 0x74, 0x0c, 0x80, 0xd6,
-      0x1a, 0x0c, 0x05, 0x80, 0xff, 0x05, 0x80, 0xdf, 0x0c, 0xee, 0x0d, 0x03,
-      0x84, 0x8d, 0x03, 0x37, 0x09, 0x81, 0x5c, 0x14, 0x80, 0xb8, 0x08, 0x80,
-      0xcb, 0x2a, 0x38, 0x03, 0x0a, 0x06, 0x38, 0x08, 0x46, 0x08, 0x0c, 0x06,
-      0x74, 0x0b, 0x1e, 0x03, 0x5a, 0x04, 0x59, 0x09, 0x80, 0x83, 0x18, 0x1c,
-      0x0a, 0x16, 0x09, 0x4c, 0x04, 0x80, 0x8a, 0x06, 0xab, 0xa4, 0x0c, 0x17,
-      0x04, 0x31, 0xa1, 0x04, 0x81, 0xda, 0x26, 0x07, 0x0c, 0x05, 0x05, 0x80,
-      0xa5, 0x11, 0x81, 0x6d, 0x10, 0x78, 0x28, 0x2a, 0x06, 0x4c, 0x04, 0x80,
-      0x8d, 0x04, 0x80, 0xbe, 0x03, 0x1b, 0x03, 0x0f, 0x0d,
-  };
-  static constexpr unsigned char normal1[] = {
-      0x5e, 0x22, 0x7b, 0x05, 0x03, 0x04, 0x2d, 0x03, 0x66, 0x03, 0x01, 0x2f,
-      0x2e, 0x80, 0x82, 0x1d, 0x03, 0x31, 0x0f, 0x1c, 0x04, 0x24, 0x09, 0x1e,
-      0x05, 0x2b, 0x05, 0x44, 0x04, 0x0e, 0x2a, 0x80, 0xaa, 0x06, 0x24, 0x04,
-      0x24, 0x04, 0x28, 0x08, 0x34, 0x0b, 0x01, 0x80, 0x90, 0x81, 0x37, 0x09,
-      0x16, 0x0a, 0x08, 0x80, 0x98, 0x39, 0x03, 0x63, 0x08, 0x09, 0x30, 0x16,
-      0x05, 0x21, 0x03, 0x1b, 0x05, 0x01, 0x40, 0x38, 0x04, 0x4b, 0x05, 0x2f,
-      0x04, 0x0a, 0x07, 0x09, 0x07, 0x40, 0x20, 0x27, 0x04, 0x0c, 0x09, 0x36,
-      0x03, 0x3a, 0x05, 0x1a, 0x07, 0x04, 0x0c, 0x07, 0x50, 0x49, 0x37, 0x33,
-      0x0d, 0x33, 0x07, 0x2e, 0x08, 0x0a, 0x81, 0x26, 0x52, 0x4e, 0x28, 0x08,
-      0x2a, 0x56, 0x1c, 0x14, 0x17, 0x09, 0x4e, 0x04, 0x1e, 0x0f, 0x43, 0x0e,
-      0x19, 0x07, 0x0a, 0x06, 0x48, 0x08, 0x27, 0x09, 0x75, 0x0b, 0x3f, 0x41,
-      0x2a, 0x06, 0x3b, 0x05, 0x0a, 0x06, 0x51, 0x06, 0x01, 0x05, 0x10, 0x03,
-      0x05, 0x80, 0x8b, 0x62, 0x1e, 0x48, 0x08, 0x0a, 0x80, 0xa6, 0x5e, 0x22,
-      0x45, 0x0b, 0x0a, 0x06, 0x0d, 0x13, 0x39, 0x07, 0x0a, 0x36, 0x2c, 0x04,
-      0x10, 0x80, 0xc0, 0x3c, 0x64, 0x53, 0x0c, 0x48, 0x09, 0x0a, 0x46, 0x45,
-      0x1b, 0x48, 0x08, 0x53, 0x1d, 0x39, 0x81, 0x07, 0x46, 0x0a, 0x1d, 0x03,
-      0x47, 0x49, 0x37, 0x03, 0x0e, 0x08, 0x0a, 0x06, 0x39, 0x07, 0x0a, 0x81,
-      0x36, 0x19, 0x80, 0xb7, 0x01, 0x0f, 0x32, 0x0d, 0x83, 0x9b, 0x66, 0x75,
-      0x0b, 0x80, 0xc4, 0x8a, 0xbc, 0x84, 0x2f, 0x8f, 0xd1, 0x82, 0x47, 0xa1,
-      0xb9, 0x82, 0x39, 0x07, 0x2a, 0x04, 0x02, 0x60, 0x26, 0x0a, 0x46, 0x0a,
-      0x28, 0x05, 0x13, 0x82, 0xb0, 0x5b, 0x65, 0x4b, 0x04, 0x39, 0x07, 0x11,
-      0x40, 0x05, 0x0b, 0x02, 0x0e, 0x97, 0xf8, 0x08, 0x84, 0xd6, 0x2a, 0x09,
-      0xa2, 0xf7, 0x81, 0x1f, 0x31, 0x03, 0x11, 0x04, 0x08, 0x81, 0x8c, 0x89,
-      0x04, 0x6b, 0x05, 0x0d, 0x03, 0x09, 0x07, 0x10, 0x93, 0x60, 0x80, 0xf6,
-      0x0a, 0x73, 0x08, 0x6e, 0x17, 0x46, 0x80, 0x9a, 0x14, 0x0c, 0x57, 0x09,
-      0x19, 0x80, 0x87, 0x81, 0x47, 0x03, 0x85, 0x42, 0x0f, 0x15, 0x85, 0x50,
-      0x2b, 0x80, 0xd5, 0x2d, 0x03, 0x1a, 0x04, 0x02, 0x81, 0x70, 0x3a, 0x05,
-      0x01, 0x85, 0x00, 0x80, 0xd7, 0x29, 0x4c, 0x04, 0x0a, 0x04, 0x02, 0x83,
-      0x11, 0x44, 0x4c, 0x3d, 0x80, 0xc2, 0x3c, 0x06, 0x01, 0x04, 0x55, 0x05,
-      0x1b, 0x34, 0x02, 0x81, 0x0e, 0x2c, 0x04, 0x64, 0x0c, 0x56, 0x0a, 0x80,
-      0xae, 0x38, 0x1d, 0x0d, 0x2c, 0x04, 0x09, 0x07, 0x02, 0x0e, 0x06, 0x80,
-      0x9a, 0x83, 0xd8, 0x08, 0x0d, 0x03, 0x0d, 0x03, 0x74, 0x0c, 0x59, 0x07,
-      0x0c, 0x14, 0x0c, 0x04, 0x38, 0x08, 0x0a, 0x06, 0x28, 0x08, 0x22, 0x4e,
-      0x81, 0x54, 0x0c, 0x15, 0x03, 0x03, 0x05, 0x07, 0x09, 0x19, 0x07, 0x07,
-      0x09, 0x03, 0x0d, 0x07, 0x29, 0x80, 0xcb, 0x25, 0x0a, 0x84, 0x06,
-  };
-  auto lower = static_cast<uint16_t>(cp);
-  if (cp < 0x10000) {
-    return is_printable(lower, singletons0,
-                        sizeof(singletons0) / sizeof(*singletons0),
-                        singletons0_lower, normal0, sizeof(normal0));
-  }
-  if (cp < 0x20000) {
-    return is_printable(lower, singletons1,
-                        sizeof(singletons1) / sizeof(*singletons1),
-                        singletons1_lower, normal1, sizeof(normal1));
-  }
-  if (0x2a6de <= cp && cp < 0x2a700) return false;
-  if (0x2b735 <= cp && cp < 0x2b740) return false;
-  if (0x2b81e <= cp && cp < 0x2b820) return false;
-  if (0x2cea2 <= cp && cp < 0x2ceb0) return false;
-  if (0x2ebe1 <= cp && cp < 0x2f800) return false;
-  if (0x2fa1e <= cp && cp < 0x30000) return false;
-  if (0x3134b <= cp && cp < 0xe0100) return false;
-  if (0xe01f0 <= cp && cp < 0x110000) return false;
-  return cp < 0x110000;
+FMT_FUNC void vprint(string_view format_str, format_args args) {
+  vprint(stdout, format_str, args);
 }
 
-}  // namespace detail
-
 FMT_END_NAMESPACE
 
 #endif  // FMT_FORMAT_INL_H_
diff --git a/lib/fmt/include/fmt-vt/format.h b/lib/fmt/include/fmt-vt/format.h
index d4d20965a5..7e9133c394 100644
--- a/lib/fmt/include/fmt-vt/format.h
+++ b/lib/fmt/include/fmt-vt/format.h
@@ -1,103 +1,60 @@
 /*
-  Formatting library for C++
-
-  Copyright (c) 2012 - present, Victor Zverovich
-
-  Permission is hereby granted, free of charge, to any person obtaining
-  a copy of this software and associated documentation files (the
-  "Software"), to deal in the Software without restriction, including
-  without limitation the rights to use, copy, modify, merge, publish,
-  distribute, sublicense, and/or sell copies of the Software, and to
-  permit persons to whom the Software is furnished to do so, subject to
-  the following conditions:
-
-  The above copyright notice and this permission notice shall be
-  included in all copies or substantial portions of the Software.
-
-  THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
-  EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
-  MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
-  NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
-  LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
-  OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
-  WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
-
-  --- Optional exception to the license ---
-
-  As an exception, if, as a result of your compiling your source code, portions
-  of this Software are embedded into a machine-executable object form of such
-  source code, you may redistribute such embedded portions in such object form
-  without including the above copyright and permission notices.
+ Formatting library for C++
+
+ Copyright (c) 2012 - present, Victor Zverovich
+
+ Permission is hereby granted, free of charge, to any person obtaining
+ a copy of this software and associated documentation files (the
+ "Software"), to deal in the Software without restriction, including
+ without limitation the rights to use, copy, modify, merge, publish,
+ distribute, sublicense, and/or sell copies of the Software, and to
+ permit persons to whom the Software is furnished to do so, subject to
+ the following conditions:
+
+ The above copyright notice and this permission notice shall be
+ included in all copies or substantial portions of the Software.
+
+ THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+ EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+ MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+ NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
+ LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
+ OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
+ WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+
+ --- Optional exception to the license ---
+
+ As an exception, if, as a result of your compiling your source code, portions
+ of this Software are embedded into a machine-executable object form of such
+ source code, you may redistribute such embedded portions in such object form
+ without including the above copyright and permission notices.
  */
 
 #ifndef FMT_FORMAT_H_
 #define FMT_FORMAT_H_
 
-#include <cmath>             // std::signbit
-#include <cstdint>           // uint32_t
-#include <cstring>           // std::memcpy
-#include <initializer_list>  // std::initializer_list
-#include <limits>            // std::numeric_limits
-#include <memory>            // std::uninitialized_copy
-#include <stdexcept>         // std::runtime_error
-#include <system_error>      // std::system_error
-
-#ifdef __cpp_lib_bit_cast
-#  include <bit>  // std::bitcast
-#endif
+#include <algorithm>
+#include <cerrno>
+#include <cmath>
+#include <cstdint>
+#include <limits>
+#include <memory>
+#include <stdexcept>
 
 #include "core.h"
 
-#if defined __cpp_inline_variables && __cpp_inline_variables >= 201606L
-#  define FMT_INLINE_VARIABLE inline
-#else
-#  define FMT_INLINE_VARIABLE
-#endif
-
-#if FMT_HAS_CPP17_ATTRIBUTE(fallthrough)
-#  define FMT_FALLTHROUGH [[fallthrough]]
-#elif defined(__clang__)
-#  define FMT_FALLTHROUGH [[clang::fallthrough]]
-#elif FMT_GCC_VERSION >= 700 && \
-    (!defined(__EDG_VERSION__) || __EDG_VERSION__ >= 520)
-#  define FMT_FALLTHROUGH [[gnu::fallthrough]]
+#ifdef __INTEL_COMPILER
+#  define FMT_ICC_VERSION __INTEL_COMPILER
+#elif defined(__ICL)
+#  define FMT_ICC_VERSION __ICL
 #else
-#  define FMT_FALLTHROUGH
-#endif
-
-#ifndef FMT_DEPRECATED
-#  if FMT_HAS_CPP14_ATTRIBUTE(deprecated) || FMT_MSC_VERSION >= 1900
-#    define FMT_DEPRECATED [[deprecated]]
-#  else
-#    if (defined(__GNUC__) && !defined(__LCC__)) || defined(__clang__)
-#      define FMT_DEPRECATED __attribute__((deprecated))
-#    elif FMT_MSC_VERSION
-#      define FMT_DEPRECATED __declspec(deprecated)
-#    else
-#      define FMT_DEPRECATED /* deprecated */
-#    endif
-#  endif
-#endif
-
-#ifndef FMT_NO_UNIQUE_ADDRESS
-#  if FMT_CPLUSPLUS >= 202002L
-#    if FMT_HAS_CPP_ATTRIBUTE(no_unique_address)
-#      define FMT_NO_UNIQUE_ADDRESS [[no_unique_address]]
-// VS2019 v16.10 and later except clang-cl (https://reviews.llvm.org/D110485)
-#    elif (FMT_MSC_VERSION >= 1929) && !FMT_CLANG_VERSION
-#      define FMT_NO_UNIQUE_ADDRESS [[msvc::no_unique_address]]
-#    endif
-#  endif
-#endif
-#ifndef FMT_NO_UNIQUE_ADDRESS
-#  define FMT_NO_UNIQUE_ADDRESS
+#  define FMT_ICC_VERSION 0
 #endif
 
-// Visibility when compiled as a shared library/object.
-#if defined(FMT_LIB_EXPORT) || defined(FMT_SHARED)
-#  define FMT_SO_VISIBILITY(value) FMT_VISIBILITY(value)
+#ifdef __NVCC__
+#  define FMT_CUDA_VERSION (__CUDACC_VER_MAJOR__ * 100 + __CUDACC_VER_MINOR__)
 #else
-#  define FMT_SO_VISIBILITY(value)
+#  define FMT_CUDA_VERSION 0
 #endif
 
 #ifdef __has_builtin
@@ -112,9 +69,35 @@
 #  define FMT_NOINLINE
 #endif
 
+#if __cplusplus == 201103L || __cplusplus == 201402L
+#  if defined(__INTEL_COMPILER) || defined(__PGI)
+#    define FMT_FALLTHROUGH
+#  elif defined(__clang__)
+#    define FMT_FALLTHROUGH [[clang::fallthrough]]
+#  elif FMT_GCC_VERSION >= 700 && \
+      (!defined(__EDG_VERSION__) || __EDG_VERSION__ >= 520)
+#    define FMT_FALLTHROUGH [[gnu::fallthrough]]
+#  else
+#    define FMT_FALLTHROUGH
+#  endif
+#elif FMT_HAS_CPP17_ATTRIBUTE(fallthrough) || \
+    (defined(_MSVC_LANG) && _MSVC_LANG >= 201703L)
+#  define FMT_FALLTHROUGH [[fallthrough]]
+#else
+#  define FMT_FALLTHROUGH
+#endif
+
+#ifndef FMT_MAYBE_UNUSED
+#  if FMT_HAS_CPP17_ATTRIBUTE(maybe_unused)
+#    define FMT_MAYBE_UNUSED [[maybe_unused]]
+#  else
+#    define FMT_MAYBE_UNUSED
+#  endif
+#endif
+
 #ifndef FMT_THROW
 #  if FMT_EXCEPTIONS
-#    if FMT_MSC_VERSION || defined(__NVCC__)
+#    if FMT_MSC_VER || FMT_NVCC
 FMT_BEGIN_NAMESPACE
 namespace detail {
 template <typename Exception> inline void do_throw(const Exception& x) {
@@ -130,8 +113,11 @@ FMT_END_NAMESPACE
 #      define FMT_THROW(x) throw x
 #    endif
 #  else
-#    define FMT_THROW(x) \
-      ::fmt::detail::assert_fail(__FILE__, __LINE__, (x).what())
+#    define FMT_THROW(x)              \
+      do {                            \
+        static_cast<void>(sizeof(x)); \
+        FMT_ASSERT(false, "");        \
+      } while (false)
 #  endif
 #endif
 
@@ -143,21 +129,10 @@ FMT_END_NAMESPACE
 #  define FMT_CATCH(x) if (false)
 #endif
 
-#ifndef FMT_MAYBE_UNUSED
-#  if FMT_HAS_CPP17_ATTRIBUTE(maybe_unused)
-#    define FMT_MAYBE_UNUSED [[maybe_unused]]
-#  else
-#    define FMT_MAYBE_UNUSED
-#  endif
-#endif
-
 #ifndef FMT_USE_USER_DEFINED_LITERALS
 // EDG based compilers (Intel, NVIDIA, Elbrus, etc), GCC and MSVC support UDLs.
-//
-// GCC before 4.9 requires a space in `operator"" _a` which is invalid in later
-// compiler versions.
-#  if (FMT_HAS_FEATURE(cxx_user_literals) || FMT_GCC_VERSION >= 409 || \
-       FMT_MSC_VERSION >= 1900) &&                                     \
+#  if (FMT_HAS_FEATURE(cxx_user_literals) || FMT_GCC_VERSION >= 407 || \
+       FMT_MSC_VER >= 1900) &&                                         \
       (!defined(__EDG_VERSION__) || __EDG_VERSION__ >= /* UDL feature */ 480)
 #    define FMT_USE_USER_DEFINED_LITERALS 1
 #  else
@@ -165,101 +140,117 @@ FMT_END_NAMESPACE
 #  endif
 #endif
 
+#ifndef FMT_USE_UDL_TEMPLATE
+// EDG frontend based compilers (icc, nvcc, PGI, etc) and GCC < 6.4 do not
+// properly support UDL templates and GCC >= 9 warns about them.
+#  if FMT_USE_USER_DEFINED_LITERALS &&                         \
+      (!defined(__EDG_VERSION__) || __EDG_VERSION__ >= 501) && \
+      ((FMT_GCC_VERSION >= 604 && __cplusplus >= 201402L) ||   \
+       FMT_CLANG_VERSION >= 304) &&                            \
+      !defined(__PGI) && !defined(__NVCC__)
+#    define FMT_USE_UDL_TEMPLATE 1
+#  else
+#    define FMT_USE_UDL_TEMPLATE 0
+#  endif
+#endif
+
+#ifndef FMT_USE_FLOAT
+#  define FMT_USE_FLOAT 1
+#endif
+
+#ifndef FMT_USE_DOUBLE
+#  define FMT_USE_DOUBLE 1
+#endif
+
+#ifndef FMT_USE_LONG_DOUBLE
+#  define FMT_USE_LONG_DOUBLE 1
+#endif
+
 // Defining FMT_REDUCE_INT_INSTANTIATIONS to 1, will reduce the number of
-// integer formatter template instantiations to just one by only using the
-// largest integer type. This results in a reduction in binary size but will
-// cause a decrease in integer formatting performance.
+// int_writer template instances to just one by only using the largest integer
+// type. This results in a reduction in binary size but will cause a decrease in
+// integer formatting performance.
 #if !defined(FMT_REDUCE_INT_INSTANTIATIONS)
 #  define FMT_REDUCE_INT_INSTANTIATIONS 0
 #endif
 
 // __builtin_clz is broken in clang with Microsoft CodeGen:
-// https://github.com/fmtlib/fmt/issues/519.
-#if !FMT_MSC_VERSION
-#  if FMT_HAS_BUILTIN(__builtin_clz) || FMT_GCC_VERSION || FMT_ICC_VERSION
-#    define FMT_BUILTIN_CLZ(n) __builtin_clz(n)
-#  endif
-#  if FMT_HAS_BUILTIN(__builtin_clzll) || FMT_GCC_VERSION || FMT_ICC_VERSION
-#    define FMT_BUILTIN_CLZLL(n) __builtin_clzll(n)
-#  endif
+// https://github.com/fmtlib/fmt/issues/519
+#if (FMT_GCC_VERSION || FMT_HAS_BUILTIN(__builtin_clz)) && !FMT_MSC_VER
+#  define FMT_BUILTIN_CLZ(n) __builtin_clz(n)
 #endif
-
-// __builtin_ctz is broken in Intel Compiler Classic on Windows:
-// https://github.com/fmtlib/fmt/issues/2510.
-#ifndef __ICL
-#  if FMT_HAS_BUILTIN(__builtin_ctz) || FMT_GCC_VERSION || FMT_ICC_VERSION || \
-      defined(__NVCOMPILER)
-#    define FMT_BUILTIN_CTZ(n) __builtin_ctz(n)
-#  endif
-#  if FMT_HAS_BUILTIN(__builtin_ctzll) || FMT_GCC_VERSION || \
-      FMT_ICC_VERSION || defined(__NVCOMPILER)
-#    define FMT_BUILTIN_CTZLL(n) __builtin_ctzll(n)
-#  endif
+#if (FMT_GCC_VERSION || FMT_HAS_BUILTIN(__builtin_clzll)) && !FMT_MSC_VER
+#  define FMT_BUILTIN_CLZLL(n) __builtin_clzll(n)
+#endif
+#if (FMT_GCC_VERSION || FMT_HAS_BUILTIN(__builtin_ctz))
+#  define FMT_BUILTIN_CTZ(n) __builtin_ctz(n)
+#endif
+#if (FMT_GCC_VERSION || FMT_HAS_BUILTIN(__builtin_ctzll))
+#  define FMT_BUILTIN_CTZLL(n) __builtin_ctzll(n)
 #endif
 
-#if FMT_MSC_VERSION
+#if FMT_MSC_VER
 #  include <intrin.h>  // _BitScanReverse[64], _BitScanForward[64], _umul128
 #endif
 
 // Some compilers masquerade as both MSVC and GCC-likes or otherwise support
 // __builtin_clz and __builtin_clzll, so only define FMT_BUILTIN_CLZ using the
 // MSVC intrinsics if the clz and clzll builtins are not available.
-#if FMT_MSC_VERSION && !defined(FMT_BUILTIN_CLZLL) && \
-    !defined(FMT_BUILTIN_CTZLL)
+#if FMT_MSC_VER && !defined(FMT_BUILTIN_CLZLL) && \
+    !defined(FMT_BUILTIN_CTZLL) && !defined(_MANAGED)
 FMT_BEGIN_NAMESPACE
 namespace detail {
 // Avoid Clang with Microsoft CodeGen's -Wunknown-pragmas warning.
-#  if !defined(__clang__)
+#  ifndef __clang__
 #    pragma intrinsic(_BitScanForward)
 #    pragma intrinsic(_BitScanReverse)
-#    if defined(_WIN64)
-#      pragma intrinsic(_BitScanForward64)
-#      pragma intrinsic(_BitScanReverse64)
-#    endif
+#  endif
+#  if defined(_WIN64) && !defined(__clang__)
+#    pragma intrinsic(_BitScanForward64)
+#    pragma intrinsic(_BitScanReverse64)
 #  endif
 
-inline auto clz(uint32_t x) -> int {
+inline int clz(uint32_t x) {
   unsigned long r = 0;
   _BitScanReverse(&r, x);
   FMT_ASSERT(x != 0, "");
   // Static analysis complains about using uninitialized data
   // "r", but the only way that can happen is if "x" is 0,
   // which the callers guarantee to not happen.
-  FMT_MSC_WARNING(suppress : 6102)
+  FMT_SUPPRESS_MSC_WARNING(6102)
   return 31 ^ static_cast<int>(r);
 }
 #  define FMT_BUILTIN_CLZ(n) detail::clz(n)
 
-inline auto clzll(uint64_t x) -> int {
+inline int clzll(uint64_t x) {
   unsigned long r = 0;
 #  ifdef _WIN64
   _BitScanReverse64(&r, x);
 #  else
   // Scan the high 32 bits.
-  if (_BitScanReverse(&r, static_cast<uint32_t>(x >> 32)))
-    return 63 ^ static_cast<int>(r + 32);
+  if (_BitScanReverse(&r, static_cast<uint32_t>(x >> 32))) return 63 ^ (r + 32);
   // Scan the low 32 bits.
   _BitScanReverse(&r, static_cast<uint32_t>(x));
 #  endif
   FMT_ASSERT(x != 0, "");
-  FMT_MSC_WARNING(suppress : 6102)  // Suppress a bogus static analysis warning.
+  FMT_SUPPRESS_MSC_WARNING(6102)  // Suppress a bogus static analysis warning.
   return 63 ^ static_cast<int>(r);
 }
 #  define FMT_BUILTIN_CLZLL(n) detail::clzll(n)
 
-inline auto ctz(uint32_t x) -> int {
+inline int ctz(uint32_t x) {
   unsigned long r = 0;
   _BitScanForward(&r, x);
   FMT_ASSERT(x != 0, "");
-  FMT_MSC_WARNING(suppress : 6102)  // Suppress a bogus static analysis warning.
+  FMT_SUPPRESS_MSC_WARNING(6102)  // Suppress a bogus static analysis warning.
   return static_cast<int>(r);
 }
 #  define FMT_BUILTIN_CTZ(n) detail::ctz(n)
 
-inline auto ctzll(uint64_t x) -> int {
+inline int ctzll(uint64_t x) {
   unsigned long r = 0;
   FMT_ASSERT(x != 0, "");
-  FMT_MSC_WARNING(suppress : 6102)  // Suppress a bogus static analysis warning.
+  FMT_SUPPRESS_MSC_WARNING(6102)  // Suppress a bogus static analysis warning.
 #  ifdef _WIN64
   _BitScanForward64(&r, x);
 #  else
@@ -276,277 +267,76 @@ inline auto ctzll(uint64_t x) -> int {
 FMT_END_NAMESPACE
 #endif
 
-FMT_BEGIN_NAMESPACE
-
-template <typename...> struct disjunction : std::false_type {};
-template <typename P> struct disjunction<P> : P {};
-template <typename P1, typename... Pn>
-struct disjunction<P1, Pn...>
-    : conditional_t<bool(P1::value), P1, disjunction<Pn...>> {};
-
-template <typename...> struct conjunction : std::true_type {};
-template <typename P> struct conjunction<P> : P {};
-template <typename P1, typename... Pn>
-struct conjunction<P1, Pn...>
-    : conditional_t<bool(P1::value), conjunction<Pn...>, P1> {};
-
-namespace detail {
-
-FMT_CONSTEXPR inline void abort_fuzzing_if(bool condition) {
-  ignore_unused(condition);
-#ifdef FMT_FUZZ
-  if (condition) throw std::runtime_error("fuzzing limit reached");
-#endif
-}
-
-template <typename CharT, CharT... C> struct string_literal {
-  static constexpr CharT value[sizeof...(C)] = {C...};
-  constexpr operator basic_string_view<CharT>() const {
-    return {value, sizeof...(C)};
-  }
-};
-
-#if FMT_CPLUSPLUS < 201703L
-template <typename CharT, CharT... C>
-constexpr CharT string_literal<CharT, C...>::value[sizeof...(C)];
+// Enable the deprecated numeric alignment.
+#ifndef FMT_DEPRECATED_NUMERIC_ALIGN
+#  define FMT_DEPRECATED_NUMERIC_ALIGN 0
 #endif
 
-template <typename Streambuf> class formatbuf : public Streambuf {
- private:
-  using char_type = typename Streambuf::char_type;
-  using streamsize = decltype(std::declval<Streambuf>().sputn(nullptr, 0));
-  using int_type = typename Streambuf::int_type;
-  using traits_type = typename Streambuf::traits_type;
-
-  buffer<char_type>& buffer_;
-
- public:
-  explicit formatbuf(buffer<char_type>& buf) : buffer_(buf) {}
-
- protected:
-  // The put area is always empty. This makes the implementation simpler and has
-  // the advantage that the streambuf and the buffer are always in sync and
-  // sputc never writes into uninitialized memory. A disadvantage is that each
-  // call to sputc always results in a (virtual) call to overflow. There is no
-  // disadvantage here for sputn since this always results in a call to xsputn.
-
-  auto overflow(int_type ch) -> int_type override {
-    if (!traits_type::eq_int_type(ch, traits_type::eof()))
-      buffer_.push_back(static_cast<char_type>(ch));
-    return ch;
-  }
-
-  auto xsputn(const char_type* s, streamsize count) -> streamsize override {
-    buffer_.append(s, s + count);
-    return count;
-  }
-};
+FMT_BEGIN_NAMESPACE
+namespace detail {
 
-// Implementation of std::bit_cast for pre-C++20.
-template <typename To, typename From, FMT_ENABLE_IF(sizeof(To) == sizeof(From))>
-FMT_CONSTEXPR20 auto bit_cast(const From& from) -> To {
-#ifdef __cpp_lib_bit_cast
-  if (is_constant_evaluated()) return std::bit_cast<To>(from);
-#endif
-  auto to = To();
-  // The cast suppresses a bogus -Wclass-memaccess on GCC.
-  std::memcpy(static_cast<void*>(&to), &from, sizeof(to));
-  return to;
+// An equivalent of `*reinterpret_cast<Dest*>(&source)` that doesn't have
+// undefined behavior (e.g. due to type aliasing).
+// Example: uint64_t d = bit_cast<uint64_t>(2.718);
+template <typename Dest, typename Source>
+inline Dest bit_cast(const Source& source) {
+  static_assert(sizeof(Dest) == sizeof(Source), "size mismatch");
+  Dest dest;
+  std::memcpy(&dest, &source, sizeof(dest));
+  return dest;
 }
 
-inline auto is_big_endian() -> bool {
-#ifdef _WIN32
-  return false;
-#elif defined(__BIG_ENDIAN__)
-  return true;
-#elif defined(__BYTE_ORDER__) && defined(__ORDER_BIG_ENDIAN__)
-  return __BYTE_ORDER__ == __ORDER_BIG_ENDIAN__;
-#else
+inline bool is_big_endian() {
+  const auto u = 1u;
   struct bytes {
-    char data[sizeof(int)];
+    char data[sizeof(u)];
   };
-  return bit_cast<bytes>(1).data[0] == 0;
-#endif
+  return bit_cast<bytes>(u).data[0] == 0;
 }
 
-class uint128_fallback {
- private:
-  uint64_t lo_, hi_;
+// A fallback implementation of uintptr_t for systems that lack it.
+struct fallback_uintptr {
+  unsigned char value[sizeof(void*)];
 
- public:
-  constexpr uint128_fallback(uint64_t hi, uint64_t lo) : lo_(lo), hi_(hi) {}
-  constexpr uint128_fallback(uint64_t value = 0) : lo_(value), hi_(0) {}
-
-  constexpr uint64_t high() const noexcept { return hi_; }
-  constexpr uint64_t low() const noexcept { return lo_; }
-
-  template <typename T, FMT_ENABLE_IF(std::is_integral<T>::value)>
-  constexpr explicit operator T() const {
-    return static_cast<T>(lo_);
-  }
-
-  friend constexpr auto operator==(const uint128_fallback& lhs,
-                                   const uint128_fallback& rhs) -> bool {
-    return lhs.hi_ == rhs.hi_ && lhs.lo_ == rhs.lo_;
-  }
-  friend constexpr auto operator!=(const uint128_fallback& lhs,
-                                   const uint128_fallback& rhs) -> bool {
-    return !(lhs == rhs);
-  }
-  friend constexpr auto operator>(const uint128_fallback& lhs,
-                                  const uint128_fallback& rhs) -> bool {
-    return lhs.hi_ != rhs.hi_ ? lhs.hi_ > rhs.hi_ : lhs.lo_ > rhs.lo_;
-  }
-  friend constexpr auto operator|(const uint128_fallback& lhs,
-                                  const uint128_fallback& rhs)
-      -> uint128_fallback {
-    return {lhs.hi_ | rhs.hi_, lhs.lo_ | rhs.lo_};
-  }
-  friend constexpr auto operator&(const uint128_fallback& lhs,
-                                  const uint128_fallback& rhs)
-      -> uint128_fallback {
-    return {lhs.hi_ & rhs.hi_, lhs.lo_ & rhs.lo_};
-  }
-  friend constexpr auto operator~(const uint128_fallback& n)
-      -> uint128_fallback {
-    return {~n.hi_, ~n.lo_};
-  }
-  friend auto operator+(const uint128_fallback& lhs,
-                        const uint128_fallback& rhs) -> uint128_fallback {
-    auto result = uint128_fallback(lhs);
-    result += rhs;
-    return result;
-  }
-  friend auto operator*(const uint128_fallback& lhs, uint32_t rhs)
-      -> uint128_fallback {
-    FMT_ASSERT(lhs.hi_ == 0, "");
-    uint64_t hi = (lhs.lo_ >> 32) * rhs;
-    uint64_t lo = (lhs.lo_ & ~uint32_t()) * rhs;
-    uint64_t new_lo = (hi << 32) + lo;
-    return {(hi >> 32) + (new_lo < lo ? 1 : 0), new_lo};
-  }
-  friend auto operator-(const uint128_fallback& lhs, uint64_t rhs)
-      -> uint128_fallback {
-    return {lhs.hi_ - (lhs.lo_ < rhs ? 1 : 0), lhs.lo_ - rhs};
-  }
-  FMT_CONSTEXPR auto operator>>(int shift) const -> uint128_fallback {
-    if (shift == 64) return {0, hi_};
-    if (shift > 64) return uint128_fallback(0, hi_) >> (shift - 64);
-    return {hi_ >> shift, (hi_ << (64 - shift)) | (lo_ >> shift)};
-  }
-  FMT_CONSTEXPR auto operator<<(int shift) const -> uint128_fallback {
-    if (shift == 64) return {lo_, 0};
-    if (shift > 64) return uint128_fallback(lo_, 0) << (shift - 64);
-    return {hi_ << shift | (lo_ >> (64 - shift)), (lo_ << shift)};
-  }
-  FMT_CONSTEXPR auto operator>>=(int shift) -> uint128_fallback& {
-    return *this = *this >> shift;
-  }
-  FMT_CONSTEXPR void operator+=(uint128_fallback n) {
-    uint64_t new_lo = lo_ + n.lo_;
-    uint64_t new_hi = hi_ + n.hi_ + (new_lo < lo_ ? 1 : 0);
-    FMT_ASSERT(new_hi >= hi_, "");
-    lo_ = new_lo;
-    hi_ = new_hi;
-  }
-  FMT_CONSTEXPR void operator&=(uint128_fallback n) {
-    lo_ &= n.lo_;
-    hi_ &= n.hi_;
-  }
-
-  FMT_CONSTEXPR20 uint128_fallback& operator+=(uint64_t n) noexcept {
-    if (is_constant_evaluated()) {
-      lo_ += n;
-      hi_ += (lo_ < n ? 1 : 0);
-      return *this;
+  fallback_uintptr() = default;
+  explicit fallback_uintptr(const void* p) {
+    *this = bit_cast<fallback_uintptr>(p);
+    if (is_big_endian()) {
+      for (size_t i = 0, j = sizeof(void*) - 1; i < j; ++i, --j)
+        std::swap(value[i], value[j]);
     }
-#if FMT_HAS_BUILTIN(__builtin_addcll) && !defined(__ibmxl__)
-    unsigned long long carry;
-    lo_ = __builtin_addcll(lo_, n, 0, &carry);
-    hi_ += carry;
-#elif FMT_HAS_BUILTIN(__builtin_ia32_addcarryx_u64) && !defined(__ibmxl__)
-    unsigned long long result;
-    auto carry = __builtin_ia32_addcarryx_u64(0, lo_, n, &result);
-    lo_ = result;
-    hi_ += carry;
-#elif defined(_MSC_VER) && defined(_M_X64)
-    auto carry = _addcarry_u64(0, lo_, n, &lo_);
-    _addcarry_u64(carry, hi_, 0, &hi_);
-#else
-    lo_ += n;
-    hi_ += (lo_ < n ? 1 : 0);
-#endif
-    return *this;
   }
 };
-
-using uint128_t = conditional_t<FMT_USE_INT128, uint128_opt, uint128_fallback>;
-
 #ifdef UINTPTR_MAX
 using uintptr_t = ::uintptr_t;
+inline uintptr_t to_uintptr(const void* p) { return bit_cast<uintptr_t>(p); }
 #else
-using uintptr_t = uint128_t;
+using uintptr_t = fallback_uintptr;
+inline fallback_uintptr to_uintptr(const void* p) {
+  return fallback_uintptr(p);
+}
 #endif
 
 // Returns the largest possible value for type T. Same as
 // std::numeric_limits<T>::max() but shorter and not affected by the max macro.
-template <typename T> constexpr auto max_value() -> T {
+template <typename T> constexpr T max_value() {
   return (std::numeric_limits<T>::max)();
 }
-template <typename T> constexpr auto num_bits() -> int {
+template <typename T> constexpr int num_bits() {
   return std::numeric_limits<T>::digits;
 }
 // std::numeric_limits<T>::digits may return 0 for 128-bit ints.
-template <> constexpr auto num_bits<int128_opt>() -> int { return 128; }
-template <> constexpr auto num_bits<uint128_t>() -> int { return 128; }
-
-// A heterogeneous bit_cast used for converting 96-bit long double to uint128_t
-// and 128-bit pointers to uint128_fallback.
-template <typename To, typename From, FMT_ENABLE_IF(sizeof(To) > sizeof(From))>
-inline auto bit_cast(const From& from) -> To {
-  constexpr auto size = static_cast<int>(sizeof(From) / sizeof(unsigned));
-  struct data_t {
-    unsigned value[static_cast<unsigned>(size)];
-  } data = bit_cast<data_t>(from);
-  auto result = To();
-  if (const_check(is_big_endian())) {
-    for (int i = 0; i < size; ++i)
-      result = (result << num_bits<unsigned>()) | data.value[i];
-  } else {
-    for (int i = size - 1; i >= 0; --i)
-      result = (result << num_bits<unsigned>()) | data.value[i];
-  }
-  return result;
-}
-
-template <typename UInt>
-FMT_CONSTEXPR20 inline auto countl_zero_fallback(UInt n) -> int {
-  int lz = 0;
-  constexpr UInt msb_mask = static_cast<UInt>(1) << (num_bits<UInt>() - 1);
-  for (; (n & msb_mask) == 0; n <<= 1) lz++;
-  return lz;
-}
-
-FMT_CONSTEXPR20 inline auto countl_zero(uint32_t n) -> int {
-#ifdef FMT_BUILTIN_CLZ
-  if (!is_constant_evaluated()) return FMT_BUILTIN_CLZ(n);
-#endif
-  return countl_zero_fallback(n);
-}
-
-FMT_CONSTEXPR20 inline auto countl_zero(uint64_t n) -> int {
-#ifdef FMT_BUILTIN_CLZLL
-  if (!is_constant_evaluated()) return FMT_BUILTIN_CLZLL(n);
-#endif
-  return countl_zero_fallback(n);
+template <> constexpr int num_bits<int128_t>() { return 128; }
+template <> constexpr int num_bits<uint128_t>() { return 128; }
+template <> constexpr int num_bits<fallback_uintptr>() {
+  return static_cast<int>(sizeof(void*) *
+                          std::numeric_limits<unsigned char>::digits);
 }
 
 FMT_INLINE void assume(bool condition) {
   (void)condition;
-#if FMT_HAS_BUILTIN(__builtin_assume) && !FMT_ICC_VERSION
+#if FMT_HAS_BUILTIN(__builtin_assume)
   __builtin_assume(condition);
-#elif FMT_GCC_VERSION
-  if (!condition) __builtin_unreachable();
 #endif
 }
 
@@ -556,51 +346,53 @@ using iterator_t = decltype(std::begin(std::declval<T&>()));
 template <typename T> using sentinel_t = decltype(std::end(std::declval<T&>()));
 
 // A workaround for std::string not having mutable data() until C++17.
-template <typename Char>
-inline auto get_data(std::basic_string<Char>& s) -> Char* {
+template <typename Char> inline Char* get_data(std::basic_string<Char>& s) {
   return &s[0];
 }
 template <typename Container>
-inline auto get_data(Container& c) -> typename Container::value_type* {
+inline typename Container::value_type* get_data(Container& c) {
   return c.data();
 }
 
-// Attempts to reserve space for n extra characters in the output range.
-// Returns a pointer to the reserved range or a reference to it.
+#if defined(_SECURE_SCL) && _SECURE_SCL
+// Make a checked iterator to avoid MSVC warnings.
+template <typename T> using checked_ptr = stdext::checked_array_iterator<T*>;
+template <typename T> checked_ptr<T> make_checked(T* p, size_t size) {
+  return {p, size};
+}
+#else
+template <typename T> using checked_ptr = T*;
+template <typename T> inline T* make_checked(T* p, size_t) { return p; }
+#endif
+
 template <typename Container, FMT_ENABLE_IF(is_contiguous<Container>::value)>
-#if FMT_CLANG_VERSION >= 307 && !FMT_ICC_VERSION
+#if FMT_CLANG_VERSION
 __attribute__((no_sanitize("undefined")))
 #endif
-inline auto
-reserve(std::back_insert_iterator<Container> it, size_t n) ->
-    typename Container::value_type* {
+inline checked_ptr<typename Container::value_type>
+reserve(std::back_insert_iterator<Container> it, size_t n) {
   Container& c = get_container(it);
   size_t size = c.size();
   c.resize(size + n);
-  return get_data(c) + size;
+  return make_checked(get_data(c) + size, n);
 }
 
 template <typename T>
-inline auto reserve(buffer_appender<T> it, size_t n) -> buffer_appender<T> {
+inline buffer_appender<T> reserve(buffer_appender<T> it, size_t n) {
   buffer<T>& buf = get_container(it);
   buf.try_reserve(buf.size() + n);
   return it;
 }
 
-template <typename Iterator>
-constexpr auto reserve(Iterator& it, size_t) -> Iterator& {
+template <typename Iterator> inline Iterator& reserve(Iterator& it, size_t) {
   return it;
 }
 
-template <typename OutputIt>
-using reserve_iterator =
-    remove_reference_t<decltype(reserve(std::declval<OutputIt&>(), 0))>;
-
 template <typename T, typename OutputIt>
-constexpr auto to_pointer(OutputIt, size_t) -> T* {
+constexpr T* to_pointer(OutputIt, size_t) {
   return nullptr;
 }
-template <typename T> auto to_pointer(buffer_appender<T> it, size_t n) -> T* {
+template <typename T> T* to_pointer(buffer_appender<T> it, size_t n) {
   buffer<T>& buf = get_container(it);
   auto size = buf.size();
   if (buf.capacity() < size + n) return nullptr;
@@ -609,268 +401,195 @@ template <typename T> auto to_pointer(buffer_appender<T> it, size_t n) -> T* {
 }
 
 template <typename Container, FMT_ENABLE_IF(is_contiguous<Container>::value)>
-inline auto base_iterator(std::back_insert_iterator<Container> it,
-                          typename Container::value_type*)
-    -> std::back_insert_iterator<Container> {
+inline std::back_insert_iterator<Container> base_iterator(
+    std::back_insert_iterator<Container>& it,
+    checked_ptr<typename Container::value_type>) {
   return it;
 }
 
 template <typename Iterator>
-constexpr auto base_iterator(Iterator, Iterator it) -> Iterator {
+inline Iterator base_iterator(Iterator, Iterator it) {
   return it;
 }
 
-// <algorithm> is spectacularly slow to compile in C++20 so use a simple fill_n
-// instead (#1998).
-template <typename OutputIt, typename Size, typename T>
-FMT_CONSTEXPR auto fill_n(OutputIt out, Size count, const T& value)
-    -> OutputIt {
-  for (Size i = 0; i < count; ++i) *out++ = value;
-  return out;
-}
-template <typename T, typename Size>
-FMT_CONSTEXPR20 auto fill_n(T* out, Size count, char value) -> T* {
-  if (is_constant_evaluated()) {
-    return fill_n<T*, Size, T>(out, count, value);
-  }
-  std::memset(out, value, to_unsigned(count));
-  return out + count;
-}
+// An output iterator that counts the number of objects written to it and
+// discards them.
+class counting_iterator {
+ private:
+  size_t count_;
 
-#ifdef __cpp_char8_t
-using char8_type = char8_t;
-#else
-enum char8_type : unsigned char {};
-#endif
+ public:
+  using iterator_category = std::output_iterator_tag;
+  using difference_type = std::ptrdiff_t;
+  using pointer = void;
+  using reference = void;
+  using _Unchecked_type = counting_iterator;  // Mark iterator as checked.
 
-template <typename OutChar, typename InputIt, typename OutputIt>
-FMT_CONSTEXPR FMT_NOINLINE auto copy_str_noinline(InputIt begin, InputIt end,
-                                                  OutputIt out) -> OutputIt {
-  return copy_str<OutChar>(begin, end, out);
-}
-
-// A public domain branchless UTF-8 decoder by Christopher Wellons:
-// https://github.com/skeeto/branchless-utf8
-/* Decode the next character, c, from s, reporting errors in e.
- *
- * Since this is a branchless decoder, four bytes will be read from the
- * buffer regardless of the actual length of the next character. This
- * means the buffer _must_ have at least three bytes of zero padding
- * following the end of the data stream.
- *
- * Errors are reported in e, which will be non-zero if the parsed
- * character was somehow invalid: invalid byte sequence, non-canonical
- * encoding, or a surrogate half.
- *
- * The function returns a pointer to the next character. When an error
- * occurs, this pointer will be a guess that depends on the particular
- * error, but it will always advance at least one byte.
- */
-FMT_CONSTEXPR inline auto utf8_decode(const char* s, uint32_t* c, int* e)
-    -> const char* {
-  constexpr const int masks[] = {0x00, 0x7f, 0x1f, 0x0f, 0x07};
-  constexpr const uint32_t mins[] = {4194304, 0, 128, 2048, 65536};
-  constexpr const int shiftc[] = {0, 18, 12, 6, 0};
-  constexpr const int shifte[] = {0, 6, 4, 2, 0};
-
-  int len = "\1\1\1\1\1\1\1\1\1\1\1\1\1\1\1\1\0\0\0\0\0\0\0\0\2\2\2\2\3\3\4"
-      [static_cast<unsigned char>(*s) >> 3];
-  // Compute the pointer to the next character early so that the next
-  // iteration can start working on the next character. Neither Clang
-  // nor GCC figure out this reordering on their own.
-  const char* next = s + len + !len;
-
-  using uchar = unsigned char;
-
-  // Assume a four-byte character and load four bytes. Unused bits are
-  // shifted out.
-  *c = uint32_t(uchar(s[0]) & masks[len]) << 18;
-  *c |= uint32_t(uchar(s[1]) & 0x3f) << 12;
-  *c |= uint32_t(uchar(s[2]) & 0x3f) << 6;
-  *c |= uint32_t(uchar(s[3]) & 0x3f) << 0;
-  *c >>= shiftc[len];
-
-  // Accumulate the various error conditions.
-  *e = (*c < mins[len]) << 6;       // non-canonical encoding
-  *e |= ((*c >> 11) == 0x1b) << 7;  // surrogate half?
-  *e |= (*c > 0x10FFFF) << 8;       // out of range?
-  *e |= (uchar(s[1]) & 0xc0) >> 2;
-  *e |= (uchar(s[2]) & 0xc0) >> 4;
-  *e |= uchar(s[3]) >> 6;
-  *e ^= 0x2a;  // top two bits of each tail byte correct?
-  *e >>= shifte[len];
-
-  return next;
-}
-
-constexpr FMT_INLINE_VARIABLE uint32_t invalid_code_point = ~uint32_t();
-
-// Invokes f(cp, sv) for every code point cp in s with sv being the string view
-// corresponding to the code point. cp is invalid_code_point on error.
-template <typename F>
-FMT_CONSTEXPR void for_each_codepoint(string_view s, F f) {
-  auto decode = [f](const char* buf_ptr, const char* ptr) {
-    auto cp = uint32_t();
-    auto error = 0;
-    auto end = utf8_decode(buf_ptr, &cp, &error);
-    bool result = f(error ? invalid_code_point : cp,
-                    string_view(ptr, error ? 1 : to_unsigned(end - buf_ptr)));
-    return result ? (error ? buf_ptr + 1 : end) : nullptr;
+  struct value_type {
+    template <typename T> void operator=(const T&) {}
   };
-  auto p = s.data();
-  const size_t block_size = 4;  // utf8_decode always reads blocks of 4 chars.
-  if (s.size() >= block_size) {
-    for (auto end = p + s.size() - block_size + 1; p < end;) {
-      p = decode(p, p);
-      if (!p) return;
-    }
+
+  counting_iterator() : count_(0) {}
+
+  size_t count() const { return count_; }
+
+  counting_iterator& operator++() {
+    ++count_;
+    return *this;
   }
-  if (auto num_chars_left = s.data() + s.size() - p) {
-    char buf[2 * block_size - 1] = {};
-    copy_str<char>(p, p + num_chars_left, buf);
-    const char* buf_ptr = buf;
-    do {
-      auto end = decode(buf_ptr, p);
-      if (!end) return;
-      p += end - buf_ptr;
-      buf_ptr = end;
-    } while (buf_ptr - buf < num_chars_left);
+  counting_iterator operator++(int) {
+    auto it = *this;
+    ++*this;
+    return it;
   }
-}
+
+  friend counting_iterator operator+(counting_iterator it, difference_type n) {
+    it.count_ += static_cast<size_t>(n);
+    return it;
+  }
+
+  value_type operator*() const { return {}; }
+};
+
+template <typename OutputIt> class truncating_iterator_base {
+ protected:
+  OutputIt out_;
+  size_t limit_;
+  size_t count_;
+
+  truncating_iterator_base(OutputIt out, size_t limit)
+      : out_(out), limit_(limit), count_(0) {}
+
+ public:
+  using iterator_category = std::output_iterator_tag;
+  using value_type = typename std::iterator_traits<OutputIt>::value_type;
+  using difference_type = void;
+  using pointer = void;
+  using reference = void;
+  using _Unchecked_type =
+      truncating_iterator_base;  // Mark iterator as checked.
+
+  OutputIt base() const { return out_; }
+  size_t count() const { return count_; }
+};
+
+// An output iterator that truncates the output and counts the number of objects
+// written to it.
+template <typename OutputIt,
+          typename Enable = typename std::is_void<
+              typename std::iterator_traits<OutputIt>::value_type>::type>
+class truncating_iterator;
+
+template <typename OutputIt>
+class truncating_iterator<OutputIt, std::false_type>
+    : public truncating_iterator_base<OutputIt> {
+  mutable typename truncating_iterator_base<OutputIt>::value_type blackhole_;
+
+ public:
+  using value_type = typename truncating_iterator_base<OutputIt>::value_type;
+
+  truncating_iterator(OutputIt out, size_t limit)
+      : truncating_iterator_base<OutputIt>(out, limit) {}
+
+  truncating_iterator& operator++() {
+    if (this->count_++ < this->limit_) ++this->out_;
+    return *this;
+  }
+
+  truncating_iterator operator++(int) {
+    auto it = *this;
+    ++*this;
+    return it;
+  }
+
+  value_type& operator*() const {
+    return this->count_ < this->limit_ ? *this->out_ : blackhole_;
+  }
+};
+
+template <typename OutputIt>
+class truncating_iterator<OutputIt, std::true_type>
+    : public truncating_iterator_base<OutputIt> {
+ public:
+  truncating_iterator(OutputIt out, size_t limit)
+      : truncating_iterator_base<OutputIt>(out, limit) {}
+
+  template <typename T> truncating_iterator& operator=(T val) {
+    if (this->count_++ < this->limit_) *this->out_++ = val;
+    return *this;
+  }
+
+  truncating_iterator& operator++() { return *this; }
+  truncating_iterator& operator++(int) { return *this; }
+  truncating_iterator& operator*() { return *this; }
+};
 
 template <typename Char>
-inline auto compute_width(basic_string_view<Char> s) -> size_t {
+inline size_t count_code_points(basic_string_view<Char> s) {
   return s.size();
 }
 
-// Computes approximate display width of a UTF-8 string.
-FMT_CONSTEXPR inline size_t compute_width(string_view s) {
+// Counts the number of code points in a UTF-8 string.
+inline size_t count_code_points(basic_string_view<char> s) {
+  const char* data = s.data();
   size_t num_code_points = 0;
-  // It is not a lambda for compatibility with C++14.
-  struct count_code_points {
-    size_t* count;
-    FMT_CONSTEXPR auto operator()(uint32_t cp, string_view) const -> bool {
-      *count += detail::to_unsigned(
-          1 +
-          (cp >= 0x1100 &&
-           (cp <= 0x115f ||  // Hangul Jamo init. consonants
-            cp == 0x2329 ||  // LEFT-POINTING ANGLE BRACKET
-            cp == 0x232a ||  // RIGHT-POINTING ANGLE BRACKET
-            // CJK ... Yi except IDEOGRAPHIC HALF FILL SPACE:
-            (cp >= 0x2e80 && cp <= 0xa4cf && cp != 0x303f) ||
-            (cp >= 0xac00 && cp <= 0xd7a3) ||    // Hangul Syllables
-            (cp >= 0xf900 && cp <= 0xfaff) ||    // CJK Compatibility Ideographs
-            (cp >= 0xfe10 && cp <= 0xfe19) ||    // Vertical Forms
-            (cp >= 0xfe30 && cp <= 0xfe6f) ||    // CJK Compatibility Forms
-            (cp >= 0xff00 && cp <= 0xff60) ||    // Fullwidth Forms
-            (cp >= 0xffe0 && cp <= 0xffe6) ||    // Fullwidth Forms
-            (cp >= 0x20000 && cp <= 0x2fffd) ||  // CJK
-            (cp >= 0x30000 && cp <= 0x3fffd) ||
-            // Miscellaneous Symbols and Pictographs + Emoticons:
-            (cp >= 0x1f300 && cp <= 0x1f64f) ||
-            // Supplemental Symbols and Pictographs:
-            (cp >= 0x1f900 && cp <= 0x1f9ff))));
-      return true;
-    }
-  };
-  // We could avoid branches by using utf8_decode directly.
-  for_each_codepoint(s, count_code_points{&num_code_points});
+  for (size_t i = 0, size = s.size(); i != size; ++i) {
+    if ((data[i] & 0xc0) != 0x80) ++num_code_points;
+  }
   return num_code_points;
 }
 
-inline auto compute_width(basic_string_view<char8_type> s) -> size_t {
-  return compute_width(
-      string_view(reinterpret_cast<const char*>(s.data()), s.size()));
+inline size_t count_code_points(basic_string_view<char8_type> s) {
+  return count_code_points(basic_string_view<char>(
+      reinterpret_cast<const char*>(s.data()), s.size()));
 }
 
 template <typename Char>
-inline auto code_point_index(basic_string_view<Char> s, size_t n) -> size_t {
+inline size_t code_point_index(basic_string_view<Char> s, size_t n) {
   size_t size = s.size();
   return n < size ? n : size;
 }
 
 // Calculates the index of the nth code point in a UTF-8 string.
-inline auto code_point_index(string_view s, size_t n) -> size_t {
-  size_t result = s.size();
-  const char* begin = s.begin();
-  for_each_codepoint(
-      s, [begin, &n, &result](uint32_t, string_view sv) {
-        if (n != 0) {
-          --n;
-          return true;
-        }
-        result = to_unsigned(sv.begin() - begin);
-        return false;
-      });
-  return result;
-}
-
-inline auto code_point_index(basic_string_view<char8_type> s, size_t n)
-    -> size_t {
-  return code_point_index(
-      string_view(reinterpret_cast<const char*>(s.data()), s.size()), n);
+inline size_t code_point_index(basic_string_view<char8_type> s, size_t n) {
+  const char8_type* data = s.data();
+  size_t num_code_points = 0;
+  for (size_t i = 0, size = s.size(); i != size; ++i) {
+    if ((data[i] & 0xc0) != 0x80 && ++num_code_points > n) {
+      return i;
+    }
+  }
+  return s.size();
 }
 
-template <typename T> struct is_integral : std::is_integral<T> {};
-template <> struct is_integral<int128_opt> : std::true_type {};
-template <> struct is_integral<uint128_t> : std::true_type {};
-
-template <typename T>
-using is_signed =
-    std::integral_constant<bool, std::numeric_limits<T>::is_signed ||
-                                     std::is_same<T, int128_opt>::value>;
-
-template <typename T>
-using is_integer =
-    bool_constant<is_integral<T>::value && !std::is_same<T, bool>::value &&
-                  !std::is_same<T, char>::value &&
-                  !std::is_same<T, wchar_t>::value>;
-
-#ifndef FMT_USE_FLOAT
-#  define FMT_USE_FLOAT 1
-#endif
-#ifndef FMT_USE_DOUBLE
-#  define FMT_USE_DOUBLE 1
-#endif
-#ifndef FMT_USE_LONG_DOUBLE
-#  define FMT_USE_LONG_DOUBLE 1
-#endif
-
-#ifndef FMT_USE_FLOAT128
-#  ifdef __clang__
-// Clang emulates GCC, so it has to appear early.
-#    if FMT_HAS_INCLUDE(<quadmath.h>)
-#      define FMT_USE_FLOAT128 1
-#    endif
-#  elif defined(__GNUC__)
-// GNU C++:
-#    if defined(_GLIBCXX_USE_FLOAT128) && !defined(__STRICT_ANSI__)
-#      define FMT_USE_FLOAT128 1
-#    endif
-#  endif
-#  ifndef FMT_USE_FLOAT128
-#    define FMT_USE_FLOAT128 0
-#  endif
-#endif
+template <typename InputIt, typename OutChar>
+using needs_conversion = bool_constant<
+    std::is_same<typename std::iterator_traits<InputIt>::value_type,
+                 char>::value &&
+    std::is_same<OutChar, char8_type>::value>;
 
-#if FMT_USE_FLOAT128
-using float128 = __float128;
-#else
-using float128 = void;
-#endif
-template <typename T> using is_float128 = std::is_same<T, float128>;
+template <typename OutChar, typename InputIt, typename OutputIt,
+          FMT_ENABLE_IF(!needs_conversion<InputIt, OutChar>::value)>
+OutputIt copy_str(InputIt begin, InputIt end, OutputIt it) {
+  return std::copy(begin, end, it);
+}
 
-template <typename T>
-using is_floating_point =
-    bool_constant<std::is_floating_point<T>::value || is_float128<T>::value>;
+template <typename OutChar, typename InputIt, typename OutputIt,
+          FMT_ENABLE_IF(needs_conversion<InputIt, OutChar>::value)>
+OutputIt copy_str(InputIt begin, InputIt end, OutputIt it) {
+  return std::transform(begin, end, it,
+                        [](char c) { return static_cast<char8_type>(c); });
+}
 
-template <typename T, bool = std::is_floating_point<T>::value>
-struct is_fast_float : bool_constant<std::numeric_limits<T>::is_iec559 &&
-                                     sizeof(T) <= sizeof(double)> {};
-template <typename T> struct is_fast_float<T, false> : std::false_type {};
+template <typename Char, typename InputIt>
+inline counting_iterator copy_str(InputIt begin, InputIt end,
+                                  counting_iterator it) {
+  return it + (end - begin);
+}
 
 template <typename T>
-using is_double_double = bool_constant<std::numeric_limits<T>::digits == 106>;
+using is_fast_float = bool_constant<std::numeric_limits<T>::is_iec559 &&
+                                    sizeof(T) <= sizeof(double)>;
 
 #ifndef FMT_USE_FULL_CACHE_DRAGONBOX
 #  define FMT_USE_FULL_CACHE_DRAGONBOX 0
@@ -879,25 +598,24 @@ using is_double_double = bool_constant<std::numeric_limits<T>::digits == 106>;
 template <typename T>
 template <typename U>
 void buffer<T>::append(const U* begin, const U* end) {
-  while (begin != end) {
+  do {
     auto count = to_unsigned(end - begin);
     try_reserve(size_ + count);
     auto free_cap = capacity_ - size_;
     if (free_cap < count) count = free_cap;
-    std::uninitialized_copy_n(begin, count, ptr_ + size_);
+    std::uninitialized_copy_n(begin, count, make_checked(ptr_ + size_, count));
     size_ += count;
     begin += count;
-  }
+  } while (begin != end);
 }
 
-template <typename T, typename Enable = void>
-struct is_locale : std::false_type {};
-template <typename T>
-struct is_locale<T, void_t<decltype(T::classic())>> : std::true_type {};
+template <typename OutputIt, typename T, typename Traits>
+void iterator_buffer<OutputIt, T, Traits>::flush() {
+  out_ = std::copy_n(data_, this->limit(this->size()), out_);
+  this->clear();
+}
 }  // namespace detail
 
-FMT_BEGIN_EXPORT
-
 // The number of characters to store in the basic_memory_buffer object itself
 // to avoid dynamic memory allocation.
 enum { inline_buffer_size = 500 };
@@ -907,12 +625,20 @@ enum { inline_buffer_size = 500 };
   A dynamically growing memory buffer for trivially copyable/constructible types
   with the first ``SIZE`` elements stored in the object itself.
 
-  You can use the ``memory_buffer`` type alias for ``char`` instead.
+  You can use one of the following type aliases for common character types:
+
+  +----------------+------------------------------+
+  | Type           | Definition                   |
+  +================+==============================+
+  | memory_buffer  | basic_memory_buffer<char>    |
+  +----------------+------------------------------+
+  | wmemory_buffer | basic_memory_buffer<wchar_t> |
+  +----------------+------------------------------+
 
   **Example**::
 
-     auto out = fmt::memory_buffer();
-     format_to(std::back_inserter(out), "The answer is {}.", 42);
+     fmt::memory_buffer out;
+     format_to(out, "The answer is {}.", 42);
 
   This will append the following output to the ``out`` object:
 
@@ -929,66 +655,43 @@ class basic_memory_buffer final : public detail::buffer<T> {
  private:
   T store_[SIZE];
 
-  // Don't inherit from Allocator to avoid generating type_info for it.
-  FMT_NO_UNIQUE_ADDRESS Allocator alloc_;
+  // Don't inherit from Allocator avoid generating type_info for it.
+  Allocator alloc_;
 
   // Deallocate memory allocated by the buffer.
-  FMT_CONSTEXPR20 void deallocate() {
+  void deallocate() {
     T* data = this->data();
     if (data != store_) alloc_.deallocate(data, this->capacity());
   }
 
  protected:
-  FMT_CONSTEXPR20 void grow(size_t size) override {
-    detail::abort_fuzzing_if(size > 5000);
-    const size_t max_size = std::allocator_traits<Allocator>::max_size(alloc_);
-    size_t old_capacity = this->capacity();
-    size_t new_capacity = old_capacity + old_capacity / 2;
-    if (size > new_capacity)
-      new_capacity = size;
-    else if (new_capacity > max_size)
-      new_capacity = size > max_size ? size : max_size;
-    T* old_data = this->data();
-    T* new_data =
-        std::allocator_traits<Allocator>::allocate(alloc_, new_capacity);
-    // Suppress a bogus -Wstringop-overflow in gcc 13.1 (#3481).
-    detail::assume(this->size() <= new_capacity);
-    // The following code doesn't throw, so the raw pointer above doesn't leak.
-    std::uninitialized_copy_n(old_data, this->size(), new_data);
-    this->set(new_data, new_capacity);
-    // deallocate must not throw according to the standard, but even if it does,
-    // the buffer already uses the new storage and will deallocate it in
-    // destructor.
-    if (old_data != store_) alloc_.deallocate(old_data, old_capacity);
-  }
+  void grow(size_t size) final FMT_OVERRIDE;
 
  public:
   using value_type = T;
   using const_reference = const T&;
 
-  FMT_CONSTEXPR20 explicit basic_memory_buffer(
-      const Allocator& alloc = Allocator())
+  explicit basic_memory_buffer(const Allocator& alloc = Allocator())
       : alloc_(alloc) {
     this->set(store_, SIZE);
-    if (detail::is_constant_evaluated()) detail::fill_n(store_, SIZE, T());
   }
-  FMT_CONSTEXPR20 ~basic_memory_buffer() { deallocate(); }
+  ~basic_memory_buffer() { deallocate(); }
 
  private:
   // Move data from other to this buffer.
-  FMT_CONSTEXPR20 void move(basic_memory_buffer& other) {
+  void move(basic_memory_buffer& other) {
     alloc_ = std::move(other.alloc_);
     T* data = other.data();
     size_t size = other.size(), capacity = other.capacity();
     if (data == other.store_) {
       this->set(store_, capacity);
-      detail::copy_str<T>(other.store_, other.store_ + size, store_);
+      std::uninitialized_copy(other.store_, other.store_ + size,
+                              detail::make_checked(store_, capacity));
     } else {
       this->set(data, capacity);
       // Set pointer to the inline array so that delete is not called
       // when deallocating.
       other.set(other.store_, 0);
-      other.clear();
     }
     this->resize(size);
   }
@@ -1000,16 +703,14 @@ class basic_memory_buffer final : public detail::buffer<T> {
     of the other object to it.
     \endrst
    */
-  FMT_CONSTEXPR20 basic_memory_buffer(basic_memory_buffer&& other) noexcept {
-    move(other);
-  }
+  basic_memory_buffer(basic_memory_buffer&& other) FMT_NOEXCEPT { move(other); }
 
   /**
     \rst
     Moves the content of the other ``basic_memory_buffer`` object to this one.
     \endrst
    */
-  auto operator=(basic_memory_buffer&& other) noexcept -> basic_memory_buffer& {
+  basic_memory_buffer& operator=(basic_memory_buffer&& other) FMT_NOEXCEPT {
     FMT_ASSERT(this != &other, "");
     deallocate();
     move(other);
@@ -1017,13 +718,13 @@ class basic_memory_buffer final : public detail::buffer<T> {
   }
 
   // Returns a copy of the allocator associated with this buffer.
-  auto get_allocator() const -> Allocator { return alloc_; }
+  Allocator get_allocator() const { return alloc_; }
 
   /**
     Resizes the buffer to contain *count* elements. If T is a POD type new
     elements may not be initialized.
    */
-  FMT_CONSTEXPR20 void resize(size_t count) { this->try_resize(count); }
+  void resize(size_t count) { this->try_resize(count); }
 
   /** Increases the buffer capacity to *new_capacity*. */
   void reserve(size_t new_capacity) { this->try_reserve(new_capacity); }
@@ -1036,121 +737,71 @@ class basic_memory_buffer final : public detail::buffer<T> {
   }
 };
 
-using memory_buffer = basic_memory_buffer<char>;
-
 template <typename T, size_t SIZE, typename Allocator>
-struct is_contiguous<basic_memory_buffer<T, SIZE, Allocator>> : std::true_type {
-};
-
-FMT_END_EXPORT
-namespace detail {
-FMT_API bool write_console(int fd, string_view text);
-FMT_API void print(std::FILE*, string_view);
-}  // namespace detail
-
-FMT_BEGIN_EXPORT
-
-// Suppress a misleading warning in older versions of clang.
-#if FMT_CLANG_VERSION
-#  pragma clang diagnostic ignored "-Wweak-vtables"
-#endif
-
-/** An error reported from a formatting function. */
-class FMT_SO_VISIBILITY("default") format_error : public std::runtime_error {
- public:
-  using std::runtime_error::runtime_error;
-};
-
-namespace detail_exported {
-#if FMT_USE_NONTYPE_TEMPLATE_ARGS
-template <typename Char, size_t N> struct fixed_string {
-  constexpr fixed_string(const Char (&str)[N]) {
-    detail::copy_str<Char, const Char*, Char*>(static_cast<const Char*>(str),
-                                               str + N, data);
-  }
-  Char data[N] = {};
-};
+void basic_memory_buffer<T, SIZE, Allocator>::grow(size_t size) {
+#ifdef FMT_FUZZ
+  if (size > 5000) throw std::runtime_error("fuzz mode - won't grow that much");
 #endif
-
-// Converts a compile-time string to basic_string_view.
-template <typename Char, size_t N>
-constexpr auto compile_string_to_view(const Char (&s)[N])
-    -> basic_string_view<Char> {
-  // Remove trailing NUL character if needed. Won't be present if this is used
-  // with a raw character array (i.e. not defined as a string).
-  return {s, N - (std::char_traits<Char>::to_int_type(s[N - 1]) == 0 ? 1 : 0)};
-}
-template <typename Char>
-constexpr auto compile_string_to_view(detail::std_string_view<Char> s)
-    -> basic_string_view<Char> {
-  return {s.data(), s.size()};
+  size_t old_capacity = this->capacity();
+  size_t new_capacity = old_capacity + old_capacity / 2;
+  if (size > new_capacity) new_capacity = size;
+  T* old_data = this->data();
+  T* new_data =
+      std::allocator_traits<Allocator>::allocate(alloc_, new_capacity);
+  // The following code doesn't throw, so the raw pointer above doesn't leak.
+  std::uninitialized_copy(old_data, old_data + this->size(),
+                          detail::make_checked(new_data, new_capacity));
+  this->set(new_data, new_capacity);
+  // deallocate must not throw according to the standard, but even if it does,
+  // the buffer already uses the new storage and will deallocate it in
+  // destructor.
+  if (old_data != store_) alloc_.deallocate(old_data, old_capacity);
 }
-}  // namespace detail_exported
-
-class loc_value {
- private:
-  basic_format_arg<format_context> value_;
-
- public:
-  template <typename T, FMT_ENABLE_IF(!detail::is_float128<T>::value)>
-  loc_value(T value) : value_(detail::make_arg<format_context>(value)) {}
 
-  template <typename T, FMT_ENABLE_IF(detail::is_float128<T>::value)>
-  loc_value(T) {}
+using memory_buffer = basic_memory_buffer<char>;
+using wmemory_buffer = basic_memory_buffer<wchar_t>;
 
-  template <typename Visitor> auto visit(Visitor&& vis) -> decltype(vis(0)) {
-    return visit_format_arg(vis, value_);
-  }
+template <typename T, size_t SIZE, typename Allocator>
+struct is_contiguous<basic_memory_buffer<T, SIZE, Allocator>> : std::true_type {
 };
 
-// A locale facet that formats values in UTF-8.
-// It is parameterized on the locale to avoid the heavy <locale> include.
-template <typename Locale> class format_facet : public Locale::facet {
- private:
-  std::string separator_;
-  std::string grouping_;
-  std::string decimal_point_;
-
- protected:
-  virtual auto do_put(appender out, loc_value val,
-                      const format_specs<>& specs) const -> bool;
-
+/** A formatting error such as invalid format string. */
+FMT_CLASS_API
+class FMT_API format_error : public std::runtime_error {
  public:
-  static FMT_API typename Locale::id id;
-
-  explicit format_facet(Locale& loc);
-  explicit format_facet(string_view sep = "",
-                        std::initializer_list<unsigned char> g = {3},
-                        std::string decimal_point = ".")
-      : separator_(sep.data(), sep.size()),
-        grouping_(g.begin(), g.end()),
-        decimal_point_(decimal_point) {}
-
-  auto put(appender out, loc_value val, const format_specs<>& specs) const
-      -> bool {
-    return do_put(out, val, specs);
-  }
+  explicit format_error(const char* message) : std::runtime_error(message) {}
+  explicit format_error(const std::string& message)
+      : std::runtime_error(message) {}
+  format_error(const format_error&) = default;
+  format_error& operator=(const format_error&) = default;
+  format_error(format_error&&) = default;
+  format_error& operator=(format_error&&) = default;
+  ~format_error() FMT_NOEXCEPT FMT_OVERRIDE;
 };
 
 namespace detail {
 
+template <typename T>
+using is_signed =
+    std::integral_constant<bool, std::numeric_limits<T>::is_signed ||
+                                     std::is_same<T, int128_t>::value>;
+
 // Returns true if value is negative, false otherwise.
 // Same as `value < 0` but doesn't produce warnings if T is an unsigned type.
 template <typename T, FMT_ENABLE_IF(is_signed<T>::value)>
-constexpr auto is_negative(T value) -> bool {
+FMT_CONSTEXPR bool is_negative(T value) {
   return value < 0;
 }
 template <typename T, FMT_ENABLE_IF(!is_signed<T>::value)>
-constexpr auto is_negative(T) -> bool {
+FMT_CONSTEXPR bool is_negative(T) {
   return false;
 }
 
-template <typename T>
-FMT_CONSTEXPR auto is_supported_floating_point(T) -> bool {
-  if (std::is_same<T, float>()) return FMT_USE_FLOAT;
-  if (std::is_same<T, double>()) return FMT_USE_DOUBLE;
-  if (std::is_same<T, long double>()) return FMT_USE_LONG_DOUBLE;
-  return true;
+template <typename T, FMT_ENABLE_IF(std::is_floating_point<T>::value)>
+FMT_CONSTEXPR bool is_supported_floating_point(T) {
+  return (std::is_same<T, float>::value && FMT_USE_FLOAT) ||
+         (std::is_same<T, double>::value && FMT_USE_DOUBLE) ||
+         (std::is_same<T, long double>::value && FMT_USE_LONG_DOUBLE);
 }
 
 // Smallest of uint32_t, uint64_t, uint128_t that is large enough to
@@ -1160,33 +811,121 @@ using uint32_or_64_or_128_t =
     conditional_t<num_bits<T>() <= 32 && !FMT_REDUCE_INT_INSTANTIATIONS,
                   uint32_t,
                   conditional_t<num_bits<T>() <= 64, uint64_t, uint128_t>>;
-template <typename T>
-using uint64_or_128_t = conditional_t<num_bits<T>() <= 64, uint64_t, uint128_t>;
-
-#define FMT_POWERS_OF_10(factor)                                             \
-  factor * 10, (factor)*100, (factor)*1000, (factor)*10000, (factor)*100000, \
-      (factor)*1000000, (factor)*10000000, (factor)*100000000,               \
-      (factor)*1000000000
-
-// Converts value in the range [0, 100) to a string.
-constexpr const char* digits2(size_t value) {
-  // GCC generates slightly better code when value is pointer-size.
-  return &"0001020304050607080910111213141516171819"
-         "2021222324252627282930313233343536373839"
-         "4041424344454647484950515253545556575859"
-         "6061626364656667686970717273747576777879"
-         "8081828384858687888990919293949596979899"[value * 2];
-}
-
-// Sign is a template parameter to workaround a bug in gcc 4.8.
-template <typename Char, typename Sign> constexpr Char sign(Sign s) {
-#if !FMT_GCC_VERSION || FMT_GCC_VERSION >= 604
-  static_assert(std::is_same<Sign, sign_t>::value, "");
+
+// 128-bit integer type used internally
+struct FMT_EXTERN_TEMPLATE_API uint128_wrapper {
+  uint128_wrapper() = default;
+
+#if FMT_USE_INT128
+  uint128_t internal_;
+
+  uint128_wrapper(uint64_t high, uint64_t low) FMT_NOEXCEPT
+      : internal_{static_cast<uint128_t>(low) |
+                  (static_cast<uint128_t>(high) << 64)} {}
+
+  uint128_wrapper(uint128_t u) : internal_{u} {}
+
+  uint64_t high() const FMT_NOEXCEPT { return uint64_t(internal_ >> 64); }
+  uint64_t low() const FMT_NOEXCEPT { return uint64_t(internal_); }
+
+  uint128_wrapper& operator+=(uint64_t n) FMT_NOEXCEPT {
+    internal_ += n;
+    return *this;
+  }
+#else
+  uint64_t high_;
+  uint64_t low_;
+
+  uint128_wrapper(uint64_t high, uint64_t low) FMT_NOEXCEPT : high_{high},
+                                                              low_{low} {}
+
+  uint64_t high() const FMT_NOEXCEPT { return high_; }
+  uint64_t low() const FMT_NOEXCEPT { return low_; }
+
+  uint128_wrapper& operator+=(uint64_t n) FMT_NOEXCEPT {
+#  if defined(_MSC_VER) && defined(_M_X64)
+    unsigned char carry = _addcarry_u64(0, low_, n, &low_);
+    _addcarry_u64(carry, high_, 0, &high_);
+    return *this;
+#  else
+    uint64_t sum = low_ + n;
+    high_ += (sum < low_ ? 1 : 0);
+    low_ = sum;
+    return *this;
+#  endif
+  }
+#endif
+};
+
+// Table entry type for divisibility test used internally
+template <typename T> struct FMT_EXTERN_TEMPLATE_API divtest_table_entry {
+  T mod_inv;
+  T max_quotient;
+};
+
+// Static data is placed in this class template for the header-only config.
+template <typename T = void> struct FMT_EXTERN_TEMPLATE_API basic_data {
+  static const uint64_t powers_of_10_64[];
+  static const uint32_t zero_or_powers_of_10_32_new[];
+  static const uint64_t zero_or_powers_of_10_64_new[];
+  static const uint64_t grisu_pow10_significands[];
+  static const int16_t grisu_pow10_exponents[];
+  static const divtest_table_entry<uint32_t> divtest_table_for_pow5_32[];
+  static const divtest_table_entry<uint64_t> divtest_table_for_pow5_64[];
+  static const uint64_t dragonbox_pow10_significands_64[];
+  static const uint128_wrapper dragonbox_pow10_significands_128[];
+  // log10(2) = 0x0.4d104d427de7fbcc...
+  static const uint64_t log10_2_significand = 0x4d104d427de7fbcc;
+#if !FMT_USE_FULL_CACHE_DRAGONBOX
+  static const uint64_t powers_of_5_64[];
+  static const uint32_t dragonbox_pow10_recovery_errors[];
 #endif
-  return static_cast<Char>("\0-+ "[s]);
+  // GCC generates slightly better code for pairs than chars.
+  using digit_pair = char[2];
+  static const digit_pair digits[];
+  static const char hex_digits[];
+  static const char foreground_color[];
+  static const char background_color[];
+  static const char reset_color[5];
+  static const wchar_t wreset_color[5];
+  static const char signs[];
+  static const char left_padding_shifts[5];
+  static const char right_padding_shifts[5];
+
+  // DEPRECATED! These are for ABI compatibility.
+  static const uint32_t zero_or_powers_of_10_32[];
+  static const uint64_t zero_or_powers_of_10_64[];
+};
+
+// Maps bsr(n) to ceil(log10(pow(2, bsr(n) + 1) - 1)).
+// This is a function instead of an array to workaround a bug in GCC10 (#1810).
+FMT_INLINE uint16_t bsr2log10(int bsr) {
+  static constexpr uint16_t data[] = {
+      1,  1,  1,  2,  2,  2,  3,  3,  3,  4,  4,  4,  4,  5,  5,  5,
+      6,  6,  6,  7,  7,  7,  7,  8,  8,  8,  9,  9,  9,  10, 10, 10,
+      10, 11, 11, 11, 12, 12, 12, 13, 13, 13, 13, 14, 14, 14, 15, 15,
+      15, 16, 16, 16, 16, 17, 17, 17, 18, 18, 18, 19, 19, 19, 19, 20};
+  return data[bsr];
 }
 
-template <typename T> FMT_CONSTEXPR auto count_digits_fallback(T n) -> int {
+#ifndef FMT_EXPORTED
+FMT_EXTERN template struct basic_data<void>;
+#endif
+
+// This is a struct rather than an alias to avoid shadowing warnings in gcc.
+struct data : basic_data<> {};
+
+#ifdef FMT_BUILTIN_CLZLL
+// Returns the number of decimal digits in n. Leading zeros are not counted
+// except for n == 0 in which case count_digits returns 1.
+inline int count_digits(uint64_t n) {
+  // https://github.com/fmtlib/format-benchmark/blob/master/digits10
+  auto t = bsr2log10(FMT_BUILTIN_CLZLL(n | 1) ^ 63);
+  return t - (n < data::zero_or_powers_of_10_64_new[t]);
+}
+#else
+// Fallback version of count_digits used when __builtin_clz is not available.
+inline int count_digits(uint64_t n) {
   int count = 1;
   for (;;) {
     // Integer division is slow so do it for a group of four digits instead
@@ -1200,146 +939,103 @@ template <typename T> FMT_CONSTEXPR auto count_digits_fallback(T n) -> int {
     count += 4;
   }
 }
-#if FMT_USE_INT128
-FMT_CONSTEXPR inline auto count_digits(uint128_opt n) -> int {
-  return count_digits_fallback(n);
-}
 #endif
 
-#ifdef FMT_BUILTIN_CLZLL
-// It is a separate function rather than a part of count_digits to workaround
-// the lack of static constexpr in constexpr functions.
-inline auto do_count_digits(uint64_t n) -> int {
-  // This has comparable performance to the version by Kendall Willets
-  // (https://github.com/fmtlib/format-benchmark/blob/master/digits10)
-  // but uses smaller tables.
-  // Maps bsr(n) to ceil(log10(pow(2, bsr(n) + 1) - 1)).
-  static constexpr uint8_t bsr2log10[] = {
-      1,  1,  1,  2,  2,  2,  3,  3,  3,  4,  4,  4,  4,  5,  5,  5,
-      6,  6,  6,  7,  7,  7,  7,  8,  8,  8,  9,  9,  9,  10, 10, 10,
-      10, 11, 11, 11, 12, 12, 12, 13, 13, 13, 13, 14, 14, 14, 15, 15,
-      15, 16, 16, 16, 16, 17, 17, 17, 18, 18, 18, 19, 19, 19, 19, 20};
-  auto t = bsr2log10[FMT_BUILTIN_CLZLL(n | 1) ^ 63];
-  static constexpr const uint64_t zero_or_powers_of_10[] = {
-      0, 0, FMT_POWERS_OF_10(1U), FMT_POWERS_OF_10(1000000000ULL),
-      10000000000000000000ULL};
-  return t - (n < zero_or_powers_of_10[t]);
+#if FMT_USE_INT128
+inline int count_digits(uint128_t n) {
+  int count = 1;
+  for (;;) {
+    // Integer division is slow so do it for a group of four digits instead
+    // of for every digit. The idea comes from the talk by Alexandrescu
+    // "Three Optimization Tips for C++". See speed-test for a comparison.
+    if (n < 10) return count;
+    if (n < 100) return count + 1;
+    if (n < 1000) return count + 2;
+    if (n < 10000) return count + 3;
+    n /= 10000U;
+    count += 4;
+  }
 }
 #endif
 
-// Returns the number of decimal digits in n. Leading zeros are not counted
-// except for n == 0 in which case count_digits returns 1.
-FMT_CONSTEXPR20 inline auto count_digits(uint64_t n) -> int {
-#ifdef FMT_BUILTIN_CLZLL
-  if (!is_constant_evaluated()) {
-    return do_count_digits(n);
-  }
-#endif
-  return count_digits_fallback(n);
+// Counts the number of digits in n. BITS = log2(radix).
+template <unsigned BITS, typename UInt> inline int count_digits(UInt n) {
+  int num_digits = 0;
+  do {
+    ++num_digits;
+  } while ((n >>= BITS) != 0);
+  return num_digits;
 }
 
-// Counts the number of digits in n. BITS = log2(radix).
-template <int BITS, typename UInt>
-FMT_CONSTEXPR auto count_digits(UInt n) -> int {
-#ifdef FMT_BUILTIN_CLZ
-  if (!is_constant_evaluated() && num_bits<UInt>() == 32)
-    return (FMT_BUILTIN_CLZ(static_cast<uint32_t>(n) | 1) ^ 31) / BITS + 1;
+template <> int count_digits<4>(detail::fallback_uintptr n);
+
+#if FMT_GCC_VERSION || FMT_CLANG_VERSION
+#  define FMT_ALWAYS_INLINE inline __attribute__((always_inline))
+#elif FMT_MSC_VER
+#  define FMT_ALWAYS_INLINE __forceinline
+#else
+#  define FMT_ALWAYS_INLINE inline
 #endif
-  // Lambda avoids unreachable code warnings from NVHPC.
-  return [](UInt m) {
-    int num_digits = 0;
-    do {
-      ++num_digits;
-    } while ((m >>= BITS) != 0);
-    return num_digits;
-  }(n);
-}
 
-#ifdef FMT_BUILTIN_CLZ
-// It is a separate function rather than a part of count_digits to workaround
-// the lack of static constexpr in constexpr functions.
-FMT_INLINE auto do_count_digits(uint32_t n) -> int {
-// An optimization by Kendall Willets from https://bit.ly/3uOIQrB.
-// This increments the upper 32 bits (log10(T) - 1) when >= T is added.
-#  define FMT_INC(T) (((sizeof(#T) - 1ull) << 32) - T)
-  static constexpr uint64_t table[] = {
-      FMT_INC(0),          FMT_INC(0),          FMT_INC(0),           // 8
-      FMT_INC(10),         FMT_INC(10),         FMT_INC(10),          // 64
-      FMT_INC(100),        FMT_INC(100),        FMT_INC(100),         // 512
-      FMT_INC(1000),       FMT_INC(1000),       FMT_INC(1000),        // 4096
-      FMT_INC(10000),      FMT_INC(10000),      FMT_INC(10000),       // 32k
-      FMT_INC(100000),     FMT_INC(100000),     FMT_INC(100000),      // 256k
-      FMT_INC(1000000),    FMT_INC(1000000),    FMT_INC(1000000),     // 2048k
-      FMT_INC(10000000),   FMT_INC(10000000),   FMT_INC(10000000),    // 16M
-      FMT_INC(100000000),  FMT_INC(100000000),  FMT_INC(100000000),   // 128M
-      FMT_INC(1000000000), FMT_INC(1000000000), FMT_INC(1000000000),  // 1024M
-      FMT_INC(1000000000), FMT_INC(1000000000)                        // 4B
-  };
-  auto inc = table[FMT_BUILTIN_CLZ(n | 1) ^ 31];
-  return static_cast<int>((n + inc) >> 32);
-}
+// To suppress unnecessary security cookie checks
+#if FMT_MSC_VER && !FMT_CLANG_VERSION
+#  define FMT_SAFEBUFFERS __declspec(safebuffers)
+#else
+#  define FMT_SAFEBUFFERS
 #endif
 
-// Optional version of count_digits for better performance on 32-bit platforms.
-FMT_CONSTEXPR20 inline auto count_digits(uint32_t n) -> int {
 #ifdef FMT_BUILTIN_CLZ
-  if (!is_constant_evaluated()) {
-    return do_count_digits(n);
-  }
-#endif
-  return count_digits_fallback(n);
+// Optional version of count_digits for better performance on 32-bit platforms.
+inline int count_digits(uint32_t n) {
+  auto t = bsr2log10(FMT_BUILTIN_CLZ(n | 1) ^ 31);
+  return t - (n < data::zero_or_powers_of_10_32_new[t]);
 }
+#endif
 
-template <typename Int> constexpr auto digits10() noexcept -> int {
+template <typename Int> constexpr int digits10() FMT_NOEXCEPT {
   return std::numeric_limits<Int>::digits10;
 }
-template <> constexpr auto digits10<int128_opt>() noexcept -> int { return 38; }
-template <> constexpr auto digits10<uint128_t>() noexcept -> int { return 38; }
+template <> constexpr int digits10<int128_t>() FMT_NOEXCEPT { return 38; }
+template <> constexpr int digits10<uint128_t>() FMT_NOEXCEPT { return 38; }
 
-template <typename Char> struct thousands_sep_result {
-  std::string grouping;
-  Char thousands_sep;
-};
+template <typename Char> FMT_API std::string grouping_impl(locale_ref loc);
+template <typename Char> inline std::string grouping(locale_ref loc) {
+  return grouping_impl<char>(loc);
+}
+template <> inline std::string grouping<wchar_t>(locale_ref loc) {
+  return grouping_impl<wchar_t>(loc);
+}
 
-template <typename Char>
-FMT_API auto thousands_sep_impl(locale_ref loc) -> thousands_sep_result<Char>;
-template <typename Char>
-inline auto thousands_sep(locale_ref loc) -> thousands_sep_result<Char> {
-  auto result = thousands_sep_impl<char>(loc);
-  return {result.grouping, Char(result.thousands_sep)};
+template <typename Char> FMT_API Char thousands_sep_impl(locale_ref loc);
+template <typename Char> inline Char thousands_sep(locale_ref loc) {
+  return Char(thousands_sep_impl<char>(loc));
 }
-template <>
-inline auto thousands_sep(locale_ref loc) -> thousands_sep_result<wchar_t> {
+template <> inline wchar_t thousands_sep(locale_ref loc) {
   return thousands_sep_impl<wchar_t>(loc);
 }
 
-template <typename Char>
-FMT_API auto decimal_point_impl(locale_ref loc) -> Char;
-template <typename Char> inline auto decimal_point(locale_ref loc) -> Char {
+template <typename Char> FMT_API Char decimal_point_impl(locale_ref loc);
+template <typename Char> inline Char decimal_point(locale_ref loc) {
   return Char(decimal_point_impl<char>(loc));
 }
-template <> inline auto decimal_point(locale_ref loc) -> wchar_t {
+template <> inline wchar_t decimal_point(locale_ref loc) {
   return decimal_point_impl<wchar_t>(loc);
 }
 
 // Compares two characters for equality.
-template <typename Char> auto equal2(const Char* lhs, const char* rhs) -> bool {
-  return lhs[0] == Char(rhs[0]) && lhs[1] == Char(rhs[1]);
+template <typename Char> bool equal2(const Char* lhs, const char* rhs) {
+  return lhs[0] == rhs[0] && lhs[1] == rhs[1];
 }
-inline auto equal2(const char* lhs, const char* rhs) -> bool {
+inline bool equal2(const char* lhs, const char* rhs) {
   return memcmp(lhs, rhs, 2) == 0;
 }
 
 // Copies two characters from src to dst.
-template <typename Char>
-FMT_CONSTEXPR20 FMT_INLINE void copy2(Char* dst, const char* src) {
-  if (!is_constant_evaluated() && sizeof(Char) == sizeof(char)) {
-    memcpy(dst, src, 2);
-    return;
-  }
+template <typename Char> void copy2(Char* dst, const char* src) {
   *dst++ = static_cast<Char>(*src++);
   *dst = static_cast<Char>(*src);
 }
+FMT_INLINE void copy2(char* dst, const char* src) { memcpy(dst, src, 2); }
 
 template <typename Iterator> struct format_decimal_result {
   Iterator begin;
@@ -1350,8 +1046,8 @@ template <typename Iterator> struct format_decimal_result {
 // buffer of specified size. The caller must ensure that the buffer is large
 // enough.
 template <typename Char, typename UInt>
-FMT_CONSTEXPR20 auto format_decimal(Char* out, UInt value, int size)
-    -> format_decimal_result<Char*> {
+inline format_decimal_result<Char*> format_decimal(Char* out, UInt value,
+                                                   int size) {
   FMT_ASSERT(size >= count_digits(value), "invalid digit count");
   out += size;
   Char* end = out;
@@ -1360,7 +1056,7 @@ FMT_CONSTEXPR20 auto format_decimal(Char* out, UInt value, int size)
     // of for every digit. The idea comes from the talk by Alexandrescu
     // "Three Optimization Tips for C++". See speed-test for a comparison.
     out -= 2;
-    copy2(out, digits2(static_cast<size_t>(value % 100)));
+    copy2(out, data::digits[value % 100]);
     value /= 100;
   }
   if (value < 10) {
@@ -1368,234 +1064,200 @@ FMT_CONSTEXPR20 auto format_decimal(Char* out, UInt value, int size)
     return {out, end};
   }
   out -= 2;
-  copy2(out, digits2(static_cast<size_t>(value)));
+  copy2(out, data::digits[value]);
   return {out, end};
 }
 
 template <typename Char, typename UInt, typename Iterator,
           FMT_ENABLE_IF(!std::is_pointer<remove_cvref_t<Iterator>>::value)>
-FMT_CONSTEXPR inline auto format_decimal(Iterator out, UInt value, int size)
-    -> format_decimal_result<Iterator> {
+inline format_decimal_result<Iterator> format_decimal(Iterator out, UInt value,
+                                                      int size) {
   // Buffer is large enough to hold all digits (digits10 + 1).
-  Char buffer[digits10<UInt>() + 1] = {};
+  Char buffer[digits10<UInt>() + 1];
   auto end = format_decimal(buffer, value, size).end;
-  return {out, detail::copy_str_noinline<Char>(buffer, end, out)};
+  return {out, detail::copy_str<Char>(buffer, end, out)};
 }
 
 template <unsigned BASE_BITS, typename Char, typename UInt>
-FMT_CONSTEXPR auto format_uint(Char* buffer, UInt value, int num_digits,
-                               bool upper = false) -> Char* {
+inline Char* format_uint(Char* buffer, UInt value, int num_digits,
+                         bool upper = false) {
   buffer += num_digits;
   Char* end = buffer;
   do {
-    const char* digits = upper ? "0123456789ABCDEF" : "0123456789abcdef";
-    unsigned digit = static_cast<unsigned>(value & ((1 << BASE_BITS) - 1));
+    const char* digits = upper ? "0123456789ABCDEF" : data::hex_digits;
+    unsigned digit = (value & ((1 << BASE_BITS) - 1));
     *--buffer = static_cast<Char>(BASE_BITS < 4 ? static_cast<char>('0' + digit)
                                                 : digits[digit]);
   } while ((value >>= BASE_BITS) != 0);
   return end;
 }
 
+template <unsigned BASE_BITS, typename Char>
+Char* format_uint(Char* buffer, detail::fallback_uintptr n, int num_digits,
+                  bool = false) {
+  auto char_digits = std::numeric_limits<unsigned char>::digits / 4;
+  int start = (num_digits + char_digits - 1) / char_digits - 1;
+  if (int start_digits = num_digits % char_digits) {
+    unsigned value = n.value[start--];
+    buffer = format_uint<BASE_BITS>(buffer, value, start_digits);
+  }
+  for (; start >= 0; --start) {
+    unsigned value = n.value[start];
+    buffer += char_digits;
+    auto p = buffer;
+    for (int i = 0; i < char_digits; ++i) {
+      unsigned digit = (value & ((1 << BASE_BITS) - 1));
+      *--p = static_cast<Char>(data::hex_digits[digit]);
+      value >>= BASE_BITS;
+    }
+  }
+  return buffer;
+}
+
 template <unsigned BASE_BITS, typename Char, typename It, typename UInt>
-FMT_CONSTEXPR inline auto format_uint(It out, UInt value, int num_digits,
-                                      bool upper = false) -> It {
+inline It format_uint(It out, UInt value, int num_digits, bool upper = false) {
   if (auto ptr = to_pointer<Char>(out, to_unsigned(num_digits))) {
     format_uint<BASE_BITS>(ptr, value, num_digits, upper);
     return out;
   }
   // Buffer should be large enough to hold all digits (digits / BASE_BITS + 1).
-  char buffer[num_bits<UInt>() / BASE_BITS + 1] = {};
+  char buffer[num_bits<UInt>() / BASE_BITS + 1];
   format_uint<BASE_BITS>(buffer, value, num_digits, upper);
-  return detail::copy_str_noinline<Char>(buffer, buffer + num_digits, out);
+  return detail::copy_str<Char>(buffer, buffer + num_digits, out);
 }
 
 // A converter from UTF-8 to UTF-16.
 class utf8_to_utf16 {
  private:
-  basic_memory_buffer<wchar_t> buffer_;
+  wmemory_buffer buffer_;
 
  public:
   FMT_API explicit utf8_to_utf16(string_view s);
-  operator basic_string_view<wchar_t>() const { return {&buffer_[0], size()}; }
-  auto size() const -> size_t { return buffer_.size() - 1; }
-  auto c_str() const -> const wchar_t* { return &buffer_[0]; }
-  auto str() const -> std::wstring { return {&buffer_[0], size()}; }
+  operator wstring_view() const { return {&buffer_[0], size()}; }
+  size_t size() const { return buffer_.size() - 1; }
+  const wchar_t* c_str() const { return &buffer_[0]; }
+  std::wstring str() const { return {&buffer_[0], size()}; }
 };
 
-enum class to_utf8_error_policy { abort, replace };
+template <typename T = void> struct null {};
 
-// A converter from UTF-16/UTF-32 (host endian) to UTF-8.
-template <typename WChar, typename Buffer = memory_buffer> class to_utf8 {
+// Workaround an array initialization issue in gcc 4.8.
+template <typename Char> struct fill_t {
  private:
-  Buffer buffer_;
+  enum { max_size = 4 };
+  Char data_[max_size] = {Char(' '), Char(0), Char(0), Char(0)};
+  unsigned char size_ = 1;
 
  public:
-  to_utf8() {}
-  explicit to_utf8(basic_string_view<WChar> s,
-                   to_utf8_error_policy policy = to_utf8_error_policy::abort) {
-    static_assert(sizeof(WChar) == 2 || sizeof(WChar) == 4,
-                  "Expect utf16 or utf32");
-    if (!convert(s, policy))
-      FMT_THROW(std::runtime_error(sizeof(WChar) == 2 ? "invalid utf16"
-                                                      : "invalid utf32"));
-  }
-  operator string_view() const { return string_view(&buffer_[0], size()); }
-  size_t size() const { return buffer_.size() - 1; }
-  const char* c_str() const { return &buffer_[0]; }
-  std::string str() const { return std::string(&buffer_[0], size()); }
-
-  // Performs conversion returning a bool instead of throwing exception on
-  // conversion error. This method may still throw in case of memory allocation
-  // error.
-  bool convert(basic_string_view<WChar> s,
-               to_utf8_error_policy policy = to_utf8_error_policy::abort) {
-    if (!convert(buffer_, s, policy)) return false;
-    buffer_.push_back(0);
-    return true;
-  }
-  static bool convert(
-      Buffer& buf, basic_string_view<WChar> s,
-      to_utf8_error_policy policy = to_utf8_error_policy::abort) {
-    for (auto p = s.begin(); p != s.end(); ++p) {
-      uint32_t c = static_cast<uint32_t>(*p);
-      if (sizeof(WChar) == 2 && c >= 0xd800 && c <= 0xdfff) {
-        // Handle a surrogate pair.
-        ++p;
-        if (p == s.end() || (c & 0xfc00) != 0xd800 || (*p & 0xfc00) != 0xdc00) {
-          if (policy == to_utf8_error_policy::abort) return false;
-          buf.append(string_view("\xEF\xBF\xBD"));
-          --p;
-        } else {
-          c = (c << 10) + static_cast<uint32_t>(*p) - 0x35fdc00;
-        }
-      } else if (c < 0x80) {
-        buf.push_back(static_cast<char>(c));
-      } else if (c < 0x800) {
-        buf.push_back(static_cast<char>(0xc0 | (c >> 6)));
-        buf.push_back(static_cast<char>(0x80 | (c & 0x3f)));
-      } else if ((c >= 0x800 && c <= 0xd7ff) || (c >= 0xe000 && c <= 0xffff)) {
-        buf.push_back(static_cast<char>(0xe0 | (c >> 12)));
-        buf.push_back(static_cast<char>(0x80 | ((c & 0xfff) >> 6)));
-        buf.push_back(static_cast<char>(0x80 | (c & 0x3f)));
-      } else if (c >= 0x10000 && c <= 0x10ffff) {
-        buf.push_back(static_cast<char>(0xf0 | (c >> 18)));
-        buf.push_back(static_cast<char>(0x80 | ((c & 0x3ffff) >> 12)));
-        buf.push_back(static_cast<char>(0x80 | ((c & 0xfff) >> 6)));
-        buf.push_back(static_cast<char>(0x80 | (c & 0x3f)));
-      } else {
-        return false;
-      }
+  FMT_CONSTEXPR void operator=(basic_string_view<Char> s) {
+    auto size = s.size();
+    if (size > max_size) {
+      FMT_THROW(format_error("invalid fill"));
+      return;
     }
-    return true;
+    for (size_t i = 0; i < size; ++i) data_[i] = s[i];
+    size_ = static_cast<unsigned char>(size);
   }
-};
-
-// Computes 128-bit result of multiplication of two 64-bit unsigned integers.
-inline uint128_fallback umul128(uint64_t x, uint64_t y) noexcept {
-#if FMT_USE_INT128
-  auto p = static_cast<uint128_opt>(x) * static_cast<uint128_opt>(y);
-  return {static_cast<uint64_t>(p >> 64), static_cast<uint64_t>(p)};
-#elif defined(_MSC_VER) && defined(_M_X64)
-  auto hi = uint64_t();
-  auto lo = _umul128(x, y, &hi);
-  return {hi, lo};
-#else
-  const uint64_t mask = static_cast<uint64_t>(max_value<uint32_t>());
-
-  uint64_t a = x >> 32;
-  uint64_t b = x & mask;
-  uint64_t c = y >> 32;
-  uint64_t d = y & mask;
 
-  uint64_t ac = a * c;
-  uint64_t bc = b * c;
-  uint64_t ad = a * d;
-  uint64_t bd = b * d;
+  size_t size() const { return size_; }
+  const Char* data() const { return data_; }
 
-  uint64_t intermediate = (bd >> 32) + (ad & mask) + (bc & mask);
-
-  return {ac + (intermediate >> 32) + (ad >> 32) + (bc >> 32),
-          (intermediate << 32) + (bd & mask)};
-#endif
-}
+  FMT_CONSTEXPR Char& operator[](size_t index) { return data_[index]; }
+  FMT_CONSTEXPR const Char& operator[](size_t index) const {
+    return data_[index];
+  }
+};
+}  // namespace detail
 
-namespace dragonbox {
-// Computes floor(log10(pow(2, e))) for e in [-2620, 2620] using the method from
-// https://fmt.dev/papers/Dragonbox.pdf#page=28, section 6.1.
-inline int floor_log10_pow2(int e) noexcept {
-  FMT_ASSERT(e <= 2620 && e >= -2620, "too large exponent");
-  static_assert((-1 >> 1) == -1, "right shift is not arithmetic");
-  return (e * 315653) >> 20;
+// We cannot use enum classes as bit fields because of a gcc bug
+// https://gcc.gnu.org/bugzilla/show_bug.cgi?id=61414.
+namespace align {
+enum type { none, left, right, center, numeric };
 }
+using align_t = align::type;
 
-inline int floor_log2_pow10(int e) noexcept {
-  FMT_ASSERT(e <= 1233 && e >= -1233, "too large exponent");
-  return (e * 1741647) >> 19;
+namespace sign {
+enum type { none, minus, plus, space };
 }
+using sign_t = sign::type;
 
-// Computes upper 64 bits of multiplication of two 64-bit unsigned integers.
-inline uint64_t umul128_upper64(uint64_t x, uint64_t y) noexcept {
-#if FMT_USE_INT128
-  auto p = static_cast<uint128_opt>(x) * static_cast<uint128_opt>(y);
-  return static_cast<uint64_t>(p >> 64);
-#elif defined(_MSC_VER) && defined(_M_X64)
-  return __umulh(x, y);
-#else
-  return umul128(x, y).high();
-#endif
-}
+// Format specifiers for built-in and string types.
+template <typename Char> struct basic_format_specs {
+  int width;
+  int precision;
+  char type;
+  align_t align : 4;
+  sign_t sign : 3;
+  bool alt : 1;  // Alternate form ('#').
+  detail::fill_t<Char> fill;
+
+  constexpr basic_format_specs()
+      : width(0),
+        precision(-1),
+        type(0),
+        align(align::none),
+        sign(sign::none),
+        alt(false) {}
+};
 
-// Computes upper 128 bits of multiplication of a 64-bit unsigned integer and a
-// 128-bit unsigned integer.
-inline uint128_fallback umul192_upper128(uint64_t x,
-                                         uint128_fallback y) noexcept {
-  uint128_fallback r = umul128(x, y.high());
-  r += umul128_upper64(x, y.low());
-  return r;
-}
+using format_specs = basic_format_specs<char>;
 
-FMT_API uint128_fallback get_cached_power(int k) noexcept;
+namespace detail {
+namespace dragonbox {
 
 // Type-specific information that Dragonbox uses.
-template <typename T, typename Enable = void> struct float_info;
+template <class T> struct float_info;
 
 template <> struct float_info<float> {
   using carrier_uint = uint32_t;
+  static const int significand_bits = 23;
   static const int exponent_bits = 8;
+  static const int min_exponent = -126;
+  static const int max_exponent = 127;
+  static const int exponent_bias = -127;
+  static const int decimal_digits = 9;
   static const int kappa = 1;
   static const int big_divisor = 100;
   static const int small_divisor = 10;
   static const int min_k = -31;
   static const int max_k = 46;
+  static const int cache_bits = 64;
+  static const int divisibility_check_by_5_threshold = 39;
+  static const int case_fc_pm_half_lower_threshold = -1;
+  static const int case_fc_pm_half_upper_threshold = 6;
+  static const int case_fc_lower_threshold = -2;
+  static const int case_fc_upper_threshold = 6;
+  static const int case_shorter_interval_left_endpoint_lower_threshold = 2;
+  static const int case_shorter_interval_left_endpoint_upper_threshold = 3;
   static const int shorter_interval_tie_lower_threshold = -35;
   static const int shorter_interval_tie_upper_threshold = -35;
+  static const int max_trailing_zeros = 7;
 };
 
 template <> struct float_info<double> {
   using carrier_uint = uint64_t;
+  static const int significand_bits = 52;
   static const int exponent_bits = 11;
+  static const int min_exponent = -1022;
+  static const int max_exponent = 1023;
+  static const int exponent_bias = -1023;
+  static const int decimal_digits = 17;
   static const int kappa = 2;
   static const int big_divisor = 1000;
   static const int small_divisor = 100;
   static const int min_k = -292;
-  static const int max_k = 341;
+  static const int max_k = 326;
+  static const int cache_bits = 128;
+  static const int divisibility_check_by_5_threshold = 86;
+  static const int case_fc_pm_half_lower_threshold = -2;
+  static const int case_fc_pm_half_upper_threshold = 9;
+  static const int case_fc_lower_threshold = -4;
+  static const int case_fc_upper_threshold = 9;
+  static const int case_shorter_interval_left_endpoint_lower_threshold = 2;
+  static const int case_shorter_interval_left_endpoint_upper_threshold = 3;
   static const int shorter_interval_tie_lower_threshold = -77;
   static const int shorter_interval_tie_upper_threshold = -77;
-};
-
-// An 80- or 128-bit floating point number.
-template <typename T>
-struct float_info<T, enable_if_t<std::numeric_limits<T>::digits == 64 ||
-                                 std::numeric_limits<T>::digits == 113 ||
-                                 is_float128<T>::value>> {
-  using carrier_uint = detail::uint128_t;
-  static const int exponent_bits = 15;
-};
-
-// A double-double floating point number.
-template <typename T>
-struct float_info<T, enable_if_t<is_double_double<T>::value>> {
-  using carrier_uint = detail::uint128_t;
+  static const int max_trailing_zeros = 16;
 };
 
 template <typename T> struct decimal_fp {
@@ -1604,40 +1266,37 @@ template <typename T> struct decimal_fp {
   int exponent;
 };
 
-template <typename T> FMT_API auto to_decimal(T x) noexcept -> decimal_fp<T>;
+template <typename T> FMT_API decimal_fp<T> to_decimal(T x) FMT_NOEXCEPT;
 }  // namespace dragonbox
 
-// Returns true iff Float has the implicit bit which is not stored.
-template <typename Float> constexpr bool has_implicit_bit() {
-  // An 80-bit FP number has a 64-bit significand an no implicit bit.
-  return std::numeric_limits<Float>::digits != 64;
+template <typename T>
+constexpr typename dragonbox::float_info<T>::carrier_uint exponent_mask() {
+  using uint = typename dragonbox::float_info<T>::carrier_uint;
+  return ((uint(1) << dragonbox::float_info<T>::exponent_bits) - 1)
+         << dragonbox::float_info<T>::significand_bits;
 }
 
-// Returns the number of significand bits stored in Float. The implicit bit is
-// not counted since it is not stored.
-template <typename Float> constexpr int num_significand_bits() {
-  // std::numeric_limits may not support __float128.
-  return is_float128<Float>() ? 112
-                              : (std::numeric_limits<Float>::digits -
-                                 (has_implicit_bit<Float>() ? 1 : 0));
-}
+// A floating-point presentation format.
+enum class float_format : unsigned char {
+  general,  // General: exponent notation or fixed point based on magnitude.
+  exp,      // Exponent notation with the default precision of 6, e.g. 1.2e-3.
+  fixed,    // Fixed point with the default precision of 6, e.g. 0.0012.
+  hex
+};
 
-template <typename Float>
-constexpr auto exponent_mask() ->
-    typename dragonbox::float_info<Float>::carrier_uint {
-  using float_uint = typename dragonbox::float_info<Float>::carrier_uint;
-  return ((float_uint(1) << dragonbox::float_info<Float>::exponent_bits) - 1)
-         << num_significand_bits<Float>();
-}
-template <typename Float> constexpr auto exponent_bias() -> int {
-  // std::numeric_limits may not support __float128.
-  return is_float128<Float>() ? 16383
-                              : std::numeric_limits<Float>::max_exponent - 1;
-}
+struct float_specs {
+  int precision;
+  float_format format : 8;
+  sign_t sign : 8;
+  bool upper : 1;
+  bool locale : 1;
+  bool binary32 : 1;
+  bool use_grisu : 1;
+  bool showpoint : 1;
+};
 
 // Writes the exponent exp in the form "[+-]d{2,3}" to buffer.
-template <typename Char, typename It>
-FMT_CONSTEXPR auto write_exponent(int exp, It it) -> It {
+template <typename Char, typename It> It write_exponent(int exp, It it) {
   FMT_ASSERT(-10000 < exp && exp < 10000, "exponent out of range");
   if (exp < 0) {
     *it++ = static_cast<Char>('-');
@@ -1646,123 +1305,185 @@ FMT_CONSTEXPR auto write_exponent(int exp, It it) -> It {
     *it++ = static_cast<Char>('+');
   }
   if (exp >= 100) {
-    const char* top = digits2(to_unsigned(exp / 100));
+    const char* top = data::digits[exp / 100];
     if (exp >= 1000) *it++ = static_cast<Char>(top[0]);
     *it++ = static_cast<Char>(top[1]);
     exp %= 100;
   }
-  const char* d = digits2(to_unsigned(exp));
+  const char* d = data::digits[exp];
   *it++ = static_cast<Char>(d[0]);
   *it++ = static_cast<Char>(d[1]);
   return it;
 }
 
-// A floating-point number f * pow(2, e) where F is an unsigned type.
-template <typename F> struct basic_fp {
-  F f;
-  int e;
-
-  static constexpr const int num_significand_bits =
-      static_cast<int>(sizeof(F) * num_bits<unsigned char>());
-
-  constexpr basic_fp() : f(0), e(0) {}
-  constexpr basic_fp(uint64_t f_val, int e_val) : f(f_val), e(e_val) {}
-
-  // Constructs fp from an IEEE754 floating-point number.
-  template <typename Float> FMT_CONSTEXPR basic_fp(Float n) { assign(n); }
-
-  // Assigns n to this and return true iff predecessor is closer than successor.
-  template <typename Float, FMT_ENABLE_IF(!is_double_double<Float>::value)>
-  FMT_CONSTEXPR auto assign(Float n) -> bool {
-    static_assert(std::numeric_limits<Float>::digits <= 113, "unsupported FP");
-    // Assume Float is in the format [sign][exponent][significand].
-    using carrier_uint = typename dragonbox::float_info<Float>::carrier_uint;
-    const auto num_float_significand_bits =
-        detail::num_significand_bits<Float>();
-    const auto implicit_bit = carrier_uint(1) << num_float_significand_bits;
-    const auto significand_mask = implicit_bit - 1;
-    auto u = bit_cast<carrier_uint>(n);
-    f = static_cast<F>(u & significand_mask);
-    auto biased_e = static_cast<int>((u & exponent_mask<Float>()) >>
-                                     num_float_significand_bits);
-    // The predecessor is closer if n is a normalized power of 2 (f == 0)
-    // other than the smallest normalized number (biased_e > 1).
-    auto is_predecessor_closer = f == 0 && biased_e > 1;
-    if (biased_e == 0)
-      biased_e = 1;  // Subnormals use biased exponent 1 (min exponent).
-    else if (has_implicit_bit<Float>())
-      f += static_cast<F>(implicit_bit);
-    e = biased_e - exponent_bias<Float>() - num_float_significand_bits;
-    if (!has_implicit_bit<Float>()) ++e;
-    return is_predecessor_closer;
-  }
-
-  template <typename Float, FMT_ENABLE_IF(is_double_double<Float>::value)>
-  FMT_CONSTEXPR auto assign(Float n) -> bool {
-    static_assert(std::numeric_limits<double>::is_iec559, "unsupported FP");
-    return assign(static_cast<double>(n));
-  }
-};
+template <typename T>
+int format_float(T value, int precision, float_specs specs, buffer<char>& buf);
 
-using fp = basic_fp<unsigned long long>;
-
-// Normalizes the value converted from double and multiplied by (1 << SHIFT).
-template <int SHIFT = 0, typename F>
-FMT_CONSTEXPR basic_fp<F> normalize(basic_fp<F> value) {
-  // Handle subnormals.
-  const auto implicit_bit = F(1) << num_significand_bits<double>();
-  const auto shifted_implicit_bit = implicit_bit << SHIFT;
-  while ((value.f & shifted_implicit_bit) == 0) {
-    value.f <<= 1;
-    --value.e;
-  }
-  // Subtract 1 to account for hidden bit.
-  const auto offset = basic_fp<F>::num_significand_bits -
-                      num_significand_bits<double>() - SHIFT - 1;
-  value.f <<= offset;
-  value.e -= offset;
-  return value;
+// Formats a floating-point number with snprintf.
+template <typename T>
+int snprintf_float(T value, int precision, float_specs specs,
+                   buffer<char>& buf);
+
+template <typename T> T promote_float(T value) { return value; }
+inline double promote_float(float value) { return static_cast<double>(value); }
+
+template <typename Handler>
+FMT_CONSTEXPR void handle_int_type_spec(char spec, Handler&& handler) {
+  switch (spec) {
+  case 0:
+  case 'd':
+    handler.on_dec();
+    break;
+  case 'x':
+  case 'X':
+    handler.on_hex();
+    break;
+  case 'b':
+  case 'B':
+    handler.on_bin();
+    break;
+  case 'o':
+    handler.on_oct();
+    break;
+#ifdef FMT_DEPRECATED_N_SPECIFIER
+  case 'n':
+#endif
+  case 'L':
+    handler.on_num();
+    break;
+  case 'c':
+    handler.on_chr();
+    break;
+  default:
+    handler.on_error();
+  }
 }
 
-// Computes lhs * rhs / pow(2, 64) rounded to nearest with half-up tie breaking.
-FMT_CONSTEXPR inline uint64_t multiply(uint64_t lhs, uint64_t rhs) {
-#if FMT_USE_INT128
-  auto product = static_cast<__uint128_t>(lhs) * rhs;
-  auto f = static_cast<uint64_t>(product >> 64);
-  return (static_cast<uint64_t>(product) & (1ULL << 63)) != 0 ? f + 1 : f;
-#else
-  // Multiply 32-bit parts of significands.
-  uint64_t mask = (1ULL << 32) - 1;
-  uint64_t a = lhs >> 32, b = lhs & mask;
-  uint64_t c = rhs >> 32, d = rhs & mask;
-  uint64_t ac = a * c, bc = b * c, ad = a * d, bd = b * d;
-  // Compute mid 64-bit of result and round.
-  uint64_t mid = (bd >> 32) + (ad & mask) + (bc & mask) + (1U << 31);
-  return ac + (ad >> 32) + (bc >> 32) + (mid >> 32);
+template <typename ErrorHandler = error_handler, typename Char>
+FMT_CONSTEXPR float_specs parse_float_type_spec(
+    const basic_format_specs<Char>& specs, ErrorHandler&& eh = {}) {
+  auto result = float_specs();
+  result.showpoint = specs.alt;
+  switch (specs.type) {
+  case 0:
+    result.format = float_format::general;
+    result.showpoint |= specs.precision > 0;
+    break;
+  case 'G':
+    result.upper = true;
+    FMT_FALLTHROUGH;
+  case 'g':
+    result.format = float_format::general;
+    break;
+  case 'E':
+    result.upper = true;
+    FMT_FALLTHROUGH;
+  case 'e':
+    result.format = float_format::exp;
+    result.showpoint |= specs.precision != 0;
+    break;
+  case 'F':
+    result.upper = true;
+    FMT_FALLTHROUGH;
+  case 'f':
+    result.format = float_format::fixed;
+    result.showpoint |= specs.precision != 0;
+    break;
+  case 'A':
+    result.upper = true;
+    FMT_FALLTHROUGH;
+  case 'a':
+    result.format = float_format::hex;
+    break;
+#ifdef FMT_DEPRECATED_N_SPECIFIER
+  case 'n':
 #endif
+  case 'L':
+    result.locale = true;
+    break;
+  default:
+    eh.on_error("invalid type specifier");
+    break;
+  }
+  return result;
+}
+
+template <typename Char, typename Handler>
+FMT_CONSTEXPR void handle_char_specs(const basic_format_specs<Char>* specs,
+                                     Handler&& handler) {
+  if (!specs) return handler.on_char();
+  if (specs->type && specs->type != 'c') return handler.on_int();
+  if (specs->align == align::numeric || specs->sign != sign::none || specs->alt)
+    handler.on_error("invalid format specifier for char");
+  handler.on_char();
 }
 
-FMT_CONSTEXPR inline fp operator*(fp x, fp y) {
-  return {multiply(x.f, y.f), x.e + y.e + 64};
+template <typename Char, typename Handler>
+FMT_CONSTEXPR void handle_cstring_type_spec(Char spec, Handler&& handler) {
+  if (spec == 0 || spec == 's')
+    handler.on_string();
+  else if (spec == 'p')
+    handler.on_pointer();
+  else
+    handler.on_error("invalid type specifier");
 }
 
-template <typename T, bool doublish = num_bits<T>() == num_bits<double>()>
-using convert_float_result =
-    conditional_t<std::is_same<T, float>::value || doublish, double, T>;
+template <typename Char, typename ErrorHandler>
+FMT_CONSTEXPR void check_string_type_spec(Char spec, ErrorHandler&& eh) {
+  if (spec != 0 && spec != 's') eh.on_error("invalid type specifier");
+}
 
-template <typename T>
-constexpr auto convert_float(T value) -> convert_float_result<T> {
-  return static_cast<convert_float_result<T>>(value);
+template <typename Char, typename ErrorHandler>
+FMT_CONSTEXPR void check_pointer_type_spec(Char spec, ErrorHandler&& eh) {
+  if (spec != 0 && spec != 'p') eh.on_error("invalid type specifier");
 }
 
+template <typename ErrorHandler> class int_type_checker : private ErrorHandler {
+ public:
+  FMT_CONSTEXPR explicit int_type_checker(ErrorHandler eh) : ErrorHandler(eh) {}
+
+  FMT_CONSTEXPR void on_dec() {}
+  FMT_CONSTEXPR void on_hex() {}
+  FMT_CONSTEXPR void on_bin() {}
+  FMT_CONSTEXPR void on_oct() {}
+  FMT_CONSTEXPR void on_num() {}
+  FMT_CONSTEXPR void on_chr() {}
+
+  FMT_CONSTEXPR void on_error() {
+    ErrorHandler::on_error("invalid type specifier");
+  }
+};
+
+template <typename ErrorHandler>
+class char_specs_checker : public ErrorHandler {
+ private:
+  char type_;
+
+ public:
+  FMT_CONSTEXPR char_specs_checker(char type, ErrorHandler eh)
+      : ErrorHandler(eh), type_(type) {}
+
+  FMT_CONSTEXPR void on_int() {
+    handle_int_type_spec(type_, int_type_checker<ErrorHandler>(*this));
+  }
+  FMT_CONSTEXPR void on_char() {}
+};
+
+template <typename ErrorHandler>
+class cstring_type_checker : public ErrorHandler {
+ public:
+  FMT_CONSTEXPR explicit cstring_type_checker(ErrorHandler eh)
+      : ErrorHandler(eh) {}
+
+  FMT_CONSTEXPR void on_string() {}
+  FMT_CONSTEXPR void on_pointer() {}
+};
+
 template <typename OutputIt, typename Char>
-FMT_NOINLINE FMT_CONSTEXPR auto fill(OutputIt it, size_t n,
-                                     const fill_t<Char>& fill) -> OutputIt {
+FMT_NOINLINE OutputIt fill(OutputIt it, size_t n, const fill_t<Char>& fill) {
   auto fill_size = fill.size();
-  if (fill_size == 1) return detail::fill_n(it, n, fill[0]);
-  auto data = fill.data();
-  for (size_t i = 0; i < n; ++i)
-    it = copy_str<Char>(data, data + fill_size, it);
+  if (fill_size == 1) return std::fill_n(it, n, fill[0]);
+  for (size_t i = 0; i < n; ++i) it = std::copy_n(fill.data(), fill_size, it);
   return it;
 }
 
@@ -1771,233 +1492,38 @@ FMT_NOINLINE FMT_CONSTEXPR auto fill(OutputIt it, size_t n,
 // width: output display width in (terminal) column positions.
 template <align::type align = align::left, typename OutputIt, typename Char,
           typename F>
-FMT_CONSTEXPR auto write_padded(OutputIt out, const format_specs<Char>& specs,
-                                size_t size, size_t width, F&& f) -> OutputIt {
+inline OutputIt write_padded(OutputIt out,
+                             const basic_format_specs<Char>& specs, size_t size,
+                             size_t width, F&& f) {
   static_assert(align == align::left || align == align::right, "");
   unsigned spec_width = to_unsigned(specs.width);
   size_t padding = spec_width > width ? spec_width - width : 0;
-  // Shifts are encoded as string literals because static constexpr is not
-  // supported in constexpr functions.
-  auto* shifts = align == align::left ? "\x1f\x1f\x00\x01" : "\x00\x1f\x00\x01";
+  auto* shifts = align == align::left ? data::left_padding_shifts
+                                      : data::right_padding_shifts;
   size_t left_padding = padding >> shifts[specs.align];
-  size_t right_padding = padding - left_padding;
   auto it = reserve(out, size + padding * specs.fill.size());
-  if (left_padding != 0) it = fill(it, left_padding, specs.fill);
+  it = fill(it, left_padding, specs.fill);
   it = f(it);
-  if (right_padding != 0) it = fill(it, right_padding, specs.fill);
+  it = fill(it, padding - left_padding, specs.fill);
   return base_iterator(out, it);
 }
 
 template <align::type align = align::left, typename OutputIt, typename Char,
           typename F>
-constexpr auto write_padded(OutputIt out, const format_specs<Char>& specs,
-                            size_t size, F&& f) -> OutputIt {
+inline OutputIt write_padded(OutputIt out,
+                             const basic_format_specs<Char>& specs, size_t size,
+                             F&& f) {
   return write_padded<align>(out, specs, size, size, f);
 }
 
-template <align::type align = align::left, typename Char, typename OutputIt>
-FMT_CONSTEXPR auto write_bytes(OutputIt out, string_view bytes,
-                               const format_specs<Char>& specs) -> OutputIt {
-  return write_padded<align>(
-      out, specs, bytes.size(), [bytes](reserve_iterator<OutputIt> it) {
-        const char* data = bytes.data();
-        return copy_str<Char>(data, data + bytes.size(), it);
-      });
-}
-
-template <typename Char, typename OutputIt, typename UIntPtr>
-auto write_ptr(OutputIt out, UIntPtr value, const format_specs<Char>* specs)
-    -> OutputIt {
-  int num_digits = count_digits<4>(value);
-  auto size = to_unsigned(num_digits) + size_t(2);
-  auto write = [=](reserve_iterator<OutputIt> it) {
-    *it++ = static_cast<Char>('0');
-    *it++ = static_cast<Char>('x');
-    return format_uint<4, Char>(it, value, num_digits);
-  };
-  return specs ? write_padded<align::right>(out, *specs, size, write)
-               : base_iterator(out, write(reserve(out, size)));
-}
-
-// Returns true iff the code point cp is printable.
-FMT_API auto is_printable(uint32_t cp) -> bool;
-
-inline auto needs_escape(uint32_t cp) -> bool {
-  return cp < 0x20 || cp == 0x7f || cp == '"' || cp == '\\' ||
-         !is_printable(cp);
-}
-
-template <typename Char> struct find_escape_result {
-  const Char* begin;
-  const Char* end;
-  uint32_t cp;
-};
-
-template <typename Char>
-using make_unsigned_char =
-    typename conditional_t<std::is_integral<Char>::value,
-                           std::make_unsigned<Char>,
-                           type_identity<uint32_t>>::type;
-
-template <typename Char>
-auto find_escape(const Char* begin, const Char* end)
-    -> find_escape_result<Char> {
-  for (; begin != end; ++begin) {
-    uint32_t cp = static_cast<make_unsigned_char<Char>>(*begin);
-    if (const_check(sizeof(Char) == 1) && cp >= 0x80) continue;
-    if (needs_escape(cp)) return {begin, begin + 1, cp};
-  }
-  return {begin, nullptr, 0};
-}
-
-inline auto find_escape(const char* begin, const char* end)
-    -> find_escape_result<char> {
-  if (!is_utf8()) return find_escape<char>(begin, end);
-  auto result = find_escape_result<char>{end, nullptr, 0};
-  for_each_codepoint(string_view(begin, to_unsigned(end - begin)),
-                     [&](uint32_t cp, string_view sv) {
-                       if (needs_escape(cp)) {
-                         result = {sv.begin(), sv.end(), cp};
-                         return false;
-                       }
-                       return true;
-                     });
-  return result;
-}
-
-#define FMT_STRING_IMPL(s, base, explicit)                                    \
-  [] {                                                                        \
-    /* Use the hidden visibility as a workaround for a GCC bug (#1973). */    \
-    /* Use a macro-like name to avoid shadowing warnings. */                  \
-    struct FMT_VISIBILITY("hidden") FMT_COMPILE_STRING : base {               \
-      using char_type FMT_MAYBE_UNUSED = fmt::remove_cvref_t<decltype(s[0])>; \
-      FMT_MAYBE_UNUSED FMT_CONSTEXPR explicit                                 \
-      operator fmt::basic_string_view<char_type>() const {                    \
-        return fmt::detail_exported::compile_string_to_view<char_type>(s);    \
-      }                                                                       \
-    };                                                                        \
-    return FMT_COMPILE_STRING();                                              \
-  }()
-
-/**
-  \rst
-  Constructs a compile-time format string from a string literal *s*.
-
-  **Example**::
-
-    // A compile-time error because 'd' is an invalid specifier for strings.
-    std::string s = fmt::format(FMT_STRING("{:d}"), "foo");
-  \endrst
- */
-#define FMT_STRING(s) FMT_STRING_IMPL(s, fmt::detail::compile_string, )
-
-template <size_t width, typename Char, typename OutputIt>
-auto write_codepoint(OutputIt out, char prefix, uint32_t cp) -> OutputIt {
-  *out++ = static_cast<Char>('\\');
-  *out++ = static_cast<Char>(prefix);
-  Char buf[width];
-  fill_n(buf, width, static_cast<Char>('0'));
-  format_uint<4>(buf, cp, width);
-  return copy_str<Char>(buf, buf + width, out);
-}
-
-template <typename OutputIt, typename Char>
-auto write_escaped_cp(OutputIt out, const find_escape_result<Char>& escape)
-    -> OutputIt {
-  auto c = static_cast<Char>(escape.cp);
-  switch (escape.cp) {
-  case '\n':
-    *out++ = static_cast<Char>('\\');
-    c = static_cast<Char>('n');
-    break;
-  case '\r':
-    *out++ = static_cast<Char>('\\');
-    c = static_cast<Char>('r');
-    break;
-  case '\t':
-    *out++ = static_cast<Char>('\\');
-    c = static_cast<Char>('t');
-    break;
-  case '"':
-    FMT_FALLTHROUGH;
-  case '\'':
-    FMT_FALLTHROUGH;
-  case '\\':
-    *out++ = static_cast<Char>('\\');
-    break;
-  default:
-    if (escape.cp < 0x100) {
-      return write_codepoint<2, Char>(out, 'x', escape.cp);
-    }
-    if (escape.cp < 0x10000) {
-      return write_codepoint<4, Char>(out, 'u', escape.cp);
-    }
-    if (escape.cp < 0x110000) {
-      return write_codepoint<8, Char>(out, 'U', escape.cp);
-    }
-    for (Char escape_char : basic_string_view<Char>(
-             escape.begin, to_unsigned(escape.end - escape.begin))) {
-      out = write_codepoint<2, Char>(out, 'x',
-                                     static_cast<uint32_t>(escape_char) & 0xFF);
-    }
-    return out;
-  }
-  *out++ = c;
-  return out;
-}
-
-template <typename Char, typename OutputIt>
-auto write_escaped_string(OutputIt out, basic_string_view<Char> str)
-    -> OutputIt {
-  *out++ = static_cast<Char>('"');
-  auto begin = str.begin(), end = str.end();
-  do {
-    auto escape = find_escape(begin, end);
-    out = copy_str<Char>(begin, escape.begin, out);
-    begin = escape.end;
-    if (!begin) break;
-    out = write_escaped_cp<OutputIt, Char>(out, escape);
-  } while (begin != end);
-  *out++ = static_cast<Char>('"');
-  return out;
-}
-
-template <typename Char, typename OutputIt>
-auto write_escaped_char(OutputIt out, Char v) -> OutputIt {
-  Char v_array[1] = {v};
-  *out++ = static_cast<Char>('\'');
-  if ((needs_escape(static_cast<uint32_t>(v)) && v != static_cast<Char>('"')) ||
-      v == static_cast<Char>('\'')) {
-    out = write_escaped_cp(out,
-                           find_escape_result<Char>{v_array, v_array + 1,
-                                                    static_cast<uint32_t>(v)});
-  } else {
-    *out++ = v;
-  }
-  *out++ = static_cast<Char>('\'');
-  return out;
-}
-
-template <typename Char, typename OutputIt>
-FMT_CONSTEXPR auto write_char(OutputIt out, Char value,
-                              const format_specs<Char>& specs) -> OutputIt {
-  bool is_debug = specs.type == presentation_type::debug;
-  return write_padded(out, specs, 1, [=](reserve_iterator<OutputIt> it) {
-    if (is_debug) return write_escaped_char(it, value);
-    *it++ = value;
-    return it;
-  });
-}
-template <typename Char, typename OutputIt>
-FMT_CONSTEXPR auto write(OutputIt out, Char value,
-                         const format_specs<Char>& specs, locale_ref loc = {})
-    -> OutputIt {
-  // char is formatted as unsigned char for consistency across platforms.
-  using unsigned_type =
-      conditional_t<std::is_same<Char, char>::value, unsigned char, unsigned>;
-  return check_char_specs(specs)
-             ? write_char(out, value, specs)
-             : write(out, static_cast<unsigned_type>(value), specs, loc);
+template <typename Char, typename OutputIt>
+OutputIt write_bytes(OutputIt out, string_view bytes,
+                     const basic_format_specs<Char>& specs) {
+  using iterator = remove_reference_t<decltype(reserve(out, 0))>;
+  return write_padded(out, specs, bytes.size(), [bytes](iterator it) {
+    const char* data = bytes.data();
+    return copy_str<Char>(data, data + bytes.size(), it);
+  });
 }
 
 // Data for write_int that doesn't depend on output iterator type. It is used to
@@ -2006,9 +1532,9 @@ template <typename Char> struct write_int_data {
   size_t size;
   size_t padding;
 
-  FMT_CONSTEXPR write_int_data(int num_digits, unsigned prefix,
-                               const format_specs<Char>& specs)
-      : size((prefix >> 24) + to_unsigned(num_digits)), padding(0) {
+  write_int_data(int num_digits, string_view prefix,
+                 const basic_format_specs<Char>& specs)
+      : size(prefix.size() + to_unsigned(num_digits)), padding(0) {
     if (specs.align == align::numeric) {
       auto width = to_unsigned(specs.width);
       if (width > size) {
@@ -2016,7 +1542,7 @@ template <typename Char> struct write_int_data {
         size = width;
       }
     } else if (specs.precision > num_digits) {
-      size = (prefix >> 24) + to_unsigned(specs.precision);
+      size = prefix.size() + to_unsigned(specs.precision);
       padding = to_unsigned(specs.precision - num_digits);
     }
   }
@@ -2024,342 +1550,491 @@ template <typename Char> struct write_int_data {
 
 // Writes an integer in the format
 //   <left-padding><prefix><numeric-padding><digits><right-padding>
-// where <digits> are written by write_digits(it).
-// prefix contains chars in three lower bytes and the size in the fourth byte.
-template <typename OutputIt, typename Char, typename W>
-FMT_CONSTEXPR FMT_INLINE auto write_int(OutputIt out, int num_digits,
-                                        unsigned prefix,
-                                        const format_specs<Char>& specs,
-                                        W write_digits) -> OutputIt {
-  // Slightly faster check for specs.width == 0 && specs.precision == -1.
-  if ((specs.width | (specs.precision + 1)) == 0) {
-    auto it = reserve(out, to_unsigned(num_digits) + (prefix >> 24));
-    if (prefix != 0) {
-      for (unsigned p = prefix & 0xffffff; p != 0; p >>= 8)
-        *it++ = static_cast<Char>(p & 0xff);
-    }
-    return base_iterator(out, write_digits(it));
-  }
+// where <digits> are written by f(it).
+template <typename OutputIt, typename Char, typename F>
+OutputIt write_int(OutputIt out, int num_digits, string_view prefix,
+                   const basic_format_specs<Char>& specs, F f) {
   auto data = write_int_data<Char>(num_digits, prefix, specs);
-  return write_padded<align::right>(
-      out, specs, data.size, [=](reserve_iterator<OutputIt> it) {
-        for (unsigned p = prefix & 0xffffff; p != 0; p >>= 8)
-          *it++ = static_cast<Char>(p & 0xff);
-        it = detail::fill_n(it, data.padding, static_cast<Char>('0'));
-        return write_digits(it);
-      });
+  using iterator = remove_reference_t<decltype(reserve(out, 0))>;
+  return write_padded<align::right>(out, specs, data.size, [=](iterator it) {
+    if (prefix.size() != 0)
+      it = copy_str<Char>(prefix.begin(), prefix.end(), it);
+    it = std::fill_n(it, data.padding, static_cast<Char>('0'));
+    return f(it);
+  });
 }
 
-template <typename Char> class digit_grouping {
- private:
-  std::string grouping_;
-  std::basic_string<Char> thousands_sep_;
+template <typename StrChar, typename Char, typename OutputIt>
+OutputIt write(OutputIt out, basic_string_view<StrChar> s,
+               const basic_format_specs<Char>& specs) {
+  auto data = s.data();
+  auto size = s.size();
+  if (specs.precision >= 0 && to_unsigned(specs.precision) < size)
+    size = code_point_index(s, to_unsigned(specs.precision));
+  auto width = specs.width != 0
+                   ? count_code_points(basic_string_view<StrChar>(data, size))
+                   : 0;
+  using iterator = remove_reference_t<decltype(reserve(out, 0))>;
+  return write_padded(out, specs, size, width, [=](iterator it) {
+    return copy_str<Char>(data, data + size, it);
+  });
+}
 
-  struct next_state {
-    std::string::const_iterator group;
-    int pos;
-  };
-  next_state initial_state() const { return {grouping_.begin(), 0}; }
+// The handle_int_type_spec handler that writes an integer.
+template <typename OutputIt, typename Char, typename UInt> struct int_writer {
+  OutputIt out;
+  locale_ref locale;
+  const basic_format_specs<Char>& specs;
+  UInt abs_value;
+  char prefix[4];
+  unsigned prefix_size;
+
+  using iterator =
+      remove_reference_t<decltype(reserve(std::declval<OutputIt&>(), 0))>;
+
+  string_view get_prefix() const { return string_view(prefix, prefix_size); }
+
+  template <typename Int>
+  int_writer(OutputIt output, locale_ref loc, Int value,
+             const basic_format_specs<Char>& s)
+      : out(output),
+        locale(loc),
+        specs(s),
+        abs_value(static_cast<UInt>(value)),
+        prefix_size(0) {
+    static_assert(std::is_same<uint32_or_64_or_128_t<Int>, UInt>::value, "");
+    if (is_negative(value)) {
+      prefix[0] = '-';
+      ++prefix_size;
+      abs_value = 0 - abs_value;
+    } else if (specs.sign != sign::none && specs.sign != sign::minus) {
+      prefix[0] = specs.sign == sign::plus ? '+' : ' ';
+      ++prefix_size;
+    }
+  }
+
+  void on_dec() {
+    auto num_digits = count_digits(abs_value);
+    out = write_int(
+        out, num_digits, get_prefix(), specs, [this, num_digits](iterator it) {
+          return format_decimal<Char>(it, abs_value, num_digits).end;
+        });
+  }
 
-  // Returns the next digit group separator position.
-  int next(next_state& state) const {
-    if (thousands_sep_.empty()) return max_value<int>();
-    if (state.group == grouping_.end()) return state.pos += grouping_.back();
-    if (*state.group <= 0 || *state.group == max_value<char>())
-      return max_value<int>();
-    state.pos += *state.group++;
-    return state.pos;
+  void on_hex() {
+    if (specs.alt) {
+      prefix[prefix_size++] = '0';
+      prefix[prefix_size++] = specs.type;
+    }
+    int num_digits = count_digits<4>(abs_value);
+    out = write_int(out, num_digits, get_prefix(), specs,
+                    [this, num_digits](iterator it) {
+                      return format_uint<4, Char>(it, abs_value, num_digits,
+                                                  specs.type != 'x');
+                    });
   }
 
- public:
-  explicit digit_grouping(locale_ref loc, bool localized = true) {
-    if (!localized) return;
-    auto sep = thousands_sep<Char>(loc);
-    grouping_ = sep.grouping;
-    if (sep.thousands_sep) thousands_sep_.assign(1, sep.thousands_sep);
-  }
-  digit_grouping(std::string grouping, std::basic_string<Char> sep)
-      : grouping_(std::move(grouping)), thousands_sep_(std::move(sep)) {}
-
-  bool has_separator() const { return !thousands_sep_.empty(); }
-
-  int count_separators(int num_digits) const {
-    int count = 0;
-    auto state = initial_state();
-    while (num_digits > next(state)) ++count;
-    return count;
-  }
-
-  // Applies grouping to digits and write the output to out.
-  template <typename Out, typename C>
-  Out apply(Out out, basic_string_view<C> digits) const {
-    auto num_digits = static_cast<int>(digits.size());
-    auto separators = basic_memory_buffer<int>();
-    separators.push_back(0);
-    auto state = initial_state();
-    while (int i = next(state)) {
-      if (i >= num_digits) break;
-      separators.push_back(i);
+  void on_bin() {
+    if (specs.alt) {
+      prefix[prefix_size++] = '0';
+      prefix[prefix_size++] = static_cast<char>(specs.type);
     }
-    for (int i = 0, sep_index = static_cast<int>(separators.size() - 1);
-         i < num_digits; ++i) {
-      if (num_digits - i == separators[sep_index]) {
-        out =
-            copy_str<Char>(thousands_sep_.data(),
-                           thousands_sep_.data() + thousands_sep_.size(), out);
-        --sep_index;
+    int num_digits = count_digits<1>(abs_value);
+    out = write_int(out, num_digits, get_prefix(), specs,
+                    [this, num_digits](iterator it) {
+                      return format_uint<1, Char>(it, abs_value, num_digits);
+                    });
+  }
+
+  void on_oct() {
+    int num_digits = count_digits<3>(abs_value);
+    if (specs.alt && specs.precision <= num_digits && abs_value != 0) {
+      // Octal prefix '0' is counted as a digit, so only add it if precision
+      // is not greater than the number of digits.
+      prefix[prefix_size++] = '0';
+    }
+    out = write_int(out, num_digits, get_prefix(), specs,
+                    [this, num_digits](iterator it) {
+                      return format_uint<3, Char>(it, abs_value, num_digits);
+                    });
+  }
+
+  enum { sep_size = 1 };
+
+  void on_num() {
+    std::string groups = grouping<Char>(locale);
+    if (groups.empty()) return on_dec();
+    auto sep = thousands_sep<Char>(locale);
+    if (!sep) return on_dec();
+    int num_digits = count_digits(abs_value);
+    int size = num_digits, n = num_digits;
+    std::string::const_iterator group = groups.cbegin();
+    while (group != groups.cend() && n > *group && *group > 0 &&
+           *group != max_value<char>()) {
+      size += sep_size;
+      n -= *group;
+      ++group;
+    }
+    if (group == groups.cend()) size += sep_size * ((n - 1) / groups.back());
+    char digits[40];
+    format_decimal(digits, abs_value, num_digits);
+    basic_memory_buffer<Char> buffer;
+    size += static_cast<int>(prefix_size);
+    const auto usize = to_unsigned(size);
+    buffer.resize(usize);
+    basic_string_view<Char> s(&sep, sep_size);
+    // Index of a decimal digit with the least significant digit having index 0.
+    int digit_index = 0;
+    group = groups.cbegin();
+    auto p = buffer.data() + size - 1;
+    for (int i = num_digits - 1; i > 0; --i) {
+      *p-- = static_cast<Char>(digits[i]);
+      if (*group <= 0 || ++digit_index % *group != 0 ||
+          *group == max_value<char>())
+        continue;
+      if (group + 1 != groups.cend()) {
+        digit_index = 0;
+        ++group;
       }
-      *out++ = static_cast<Char>(digits[to_unsigned(i)]);
+      std::uninitialized_copy(s.data(), s.data() + s.size(),
+                              make_checked(p, s.size()));
+      p -= s.size();
     }
-    return out;
+    *p-- = static_cast<Char>(*digits);
+    if (prefix_size != 0) *p = static_cast<Char>('-');
+    auto data = buffer.data();
+    out = write_padded<align::right>(
+        out, specs, usize, usize,
+        [=](iterator it) { return copy_str<Char>(data, data + size, it); });
   }
-};
 
-// Writes a decimal integer with digit grouping.
-template <typename OutputIt, typename UInt, typename Char>
-auto write_int(OutputIt out, UInt value, unsigned prefix,
-               const format_specs<Char>& specs,
-               const digit_grouping<Char>& grouping) -> OutputIt {
-  static_assert(std::is_same<uint64_or_128_t<UInt>, UInt>::value, "");
-  int num_digits = count_digits(value);
-  char digits[40];
-  format_decimal(digits, value, num_digits);
-  unsigned size = to_unsigned((prefix != 0 ? 1 : 0) + num_digits +
-                              grouping.count_separators(num_digits));
-  return write_padded<align::right>(
-      out, specs, size, size, [&](reserve_iterator<OutputIt> it) {
-        if (prefix != 0) {
-          char sign = static_cast<char>(prefix);
-          *it++ = static_cast<Char>(sign);
-        }
-        return grouping.apply(it, string_view(digits, to_unsigned(num_digits)));
-      });
-}
-
-// Writes a localized value.
-FMT_API auto write_loc(appender out, loc_value value,
-                       const format_specs<>& specs, locale_ref loc) -> bool;
-template <typename OutputIt, typename Char>
-inline auto write_loc(OutputIt, loc_value, const format_specs<Char>&,
-                      locale_ref) -> bool {
-  return false;
-}
+  void on_chr() { *out++ = static_cast<Char>(abs_value); }
+
+  FMT_NORETURN void on_error() {
+    FMT_THROW(format_error("invalid type specifier"));
+  }
+};
 
-FMT_CONSTEXPR inline void prefix_append(unsigned& prefix, unsigned value) {
-  prefix |= prefix != 0 ? value << 8 : value;
-  prefix += (1u + (value > 0xff ? 1 : 0)) << 24;
+template <typename Char, typename OutputIt>
+OutputIt write_nonfinite(OutputIt out, bool isinf,
+                         const basic_format_specs<Char>& specs,
+                         const float_specs& fspecs) {
+  auto str =
+      isinf ? (fspecs.upper ? "INF" : "inf") : (fspecs.upper ? "NAN" : "nan");
+  constexpr size_t str_size = 3;
+  auto sign = fspecs.sign;
+  auto size = str_size + (sign ? 1 : 0);
+  using iterator = remove_reference_t<decltype(reserve(out, 0))>;
+  return write_padded(out, specs, size, [=](iterator it) {
+    if (sign) *it++ = static_cast<Char>(data::signs[sign]);
+    return copy_str<Char>(str, str + str_size, it);
+  });
 }
 
-template <typename UInt> struct write_int_arg {
-  UInt abs_value;
-  unsigned prefix;
+// A decimal floating-point number significand * pow(10, exp).
+struct big_decimal_fp {
+  const char* significand;
+  int significand_size;
+  int exponent;
 };
 
+inline int get_significand_size(const big_decimal_fp& fp) {
+  return fp.significand_size;
+}
 template <typename T>
-FMT_CONSTEXPR auto make_write_int_arg(T value, sign_t sign)
-    -> write_int_arg<uint32_or_64_or_128_t<T>> {
-  auto prefix = 0u;
-  auto abs_value = static_cast<uint32_or_64_or_128_t<T>>(value);
-  if (is_negative(value)) {
-    prefix = 0x01000000 | '-';
-    abs_value = 0 - abs_value;
-  } else {
-    constexpr const unsigned prefixes[4] = {0, 0, 0x1000000u | '+',
-                                            0x1000000u | ' '};
-    prefix = prefixes[sign];
-  }
-  return {abs_value, prefix};
+inline int get_significand_size(const dragonbox::decimal_fp<T>& fp) {
+  return count_digits(fp.significand);
 }
 
-template <typename Char = char> struct loc_writer {
-  buffer_appender<Char> out;
-  const format_specs<Char>& specs;
-  std::basic_string<Char> sep;
-  std::string grouping;
-  std::basic_string<Char> decimal_point;
+template <typename Char, typename OutputIt>
+inline OutputIt write_significand(OutputIt out, const char* significand,
+                                  int& significand_size) {
+  return copy_str<Char>(significand, significand + significand_size, out);
+}
+template <typename Char, typename OutputIt, typename UInt>
+inline OutputIt write_significand(OutputIt out, UInt significand,
+                                  int significand_size) {
+  return format_decimal<Char>(out, significand, significand_size).end;
+}
 
-  template <typename T, FMT_ENABLE_IF(is_integer<T>::value)>
-  auto operator()(T value) -> bool {
-    auto arg = make_write_int_arg(value, specs.sign);
-    write_int(out, static_cast<uint64_or_128_t<T>>(arg.abs_value), arg.prefix,
-              specs, digit_grouping<Char>(grouping, sep));
-    return true;
+template <typename Char, typename UInt,
+          FMT_ENABLE_IF(std::is_integral<UInt>::value)>
+inline Char* write_significand(Char* out, UInt significand,
+                               int significand_size, int integral_size,
+                               Char decimal_point) {
+  if (!decimal_point)
+    return format_decimal(out, significand, significand_size).end;
+  auto end = format_decimal(out + 1, significand, significand_size).end;
+  if (integral_size == 1)
+    out[0] = out[1];
+  else
+    std::copy_n(out + 1, integral_size, out);
+  out[integral_size] = decimal_point;
+  return end;
+}
+
+template <typename OutputIt, typename UInt, typename Char,
+          FMT_ENABLE_IF(!std::is_pointer<remove_cvref_t<OutputIt>>::value)>
+inline OutputIt write_significand(OutputIt out, UInt significand,
+                                  int significand_size, int integral_size,
+                                  Char decimal_point) {
+  // Buffer is large enough to hold digits (digits10 + 1) and a decimal point.
+  Char buffer[digits10<UInt>() + 2];
+  auto end = write_significand(buffer, significand, significand_size,
+                               integral_size, decimal_point);
+  return detail::copy_str<Char>(buffer, end, out);
+}
+
+template <typename OutputIt, typename Char>
+inline OutputIt write_significand(OutputIt out, const char* significand,
+                                  int significand_size, int integral_size,
+                                  Char decimal_point) {
+  out = detail::copy_str<Char>(significand, significand + integral_size, out);
+  if (!decimal_point) return out;
+  *out++ = decimal_point;
+  return detail::copy_str<Char>(significand + integral_size,
+                                significand + significand_size, out);
+}
+
+template <typename OutputIt, typename DecimalFP, typename Char>
+OutputIt write_float(OutputIt out, const DecimalFP& fp,
+                     const basic_format_specs<Char>& specs, float_specs fspecs,
+                     Char decimal_point) {
+  auto significand = fp.significand;
+  int significand_size = get_significand_size(fp);
+  static const Char zero = static_cast<Char>('0');
+  auto sign = fspecs.sign;
+  size_t size = to_unsigned(significand_size) + (sign ? 1 : 0);
+  using iterator = remove_reference_t<decltype(reserve(out, 0))>;
+
+  int output_exp = fp.exponent + significand_size - 1;
+  auto use_exp_format = [=]() {
+    if (fspecs.format == float_format::exp) return true;
+    if (fspecs.format != float_format::general) return false;
+    // Use the fixed notation if the exponent is in [exp_lower, exp_upper),
+    // e.g. 0.0001 instead of 1e-04. Otherwise use the exponent notation.
+    const int exp_lower = -4, exp_upper = 16;
+    return output_exp < exp_lower ||
+           output_exp >= (fspecs.precision > 0 ? fspecs.precision : exp_upper);
+  };
+  if (use_exp_format()) {
+    int num_zeros = 0;
+    if (fspecs.showpoint) {
+      num_zeros = (std::max)(fspecs.precision - significand_size, 0);
+      size += to_unsigned(num_zeros);
+    } else if (significand_size == 1) {
+      decimal_point = Char();
+    }
+    auto abs_output_exp = output_exp >= 0 ? output_exp : -output_exp;
+    int exp_digits = 2;
+    if (abs_output_exp >= 100) exp_digits = abs_output_exp >= 1000 ? 4 : 3;
+
+    size += to_unsigned((decimal_point ? 1 : 0) + 2 + exp_digits);
+    char exp_char = fspecs.upper ? 'E' : 'e';
+    auto write = [=](iterator it) {
+      if (sign) *it++ = static_cast<Char>(data::signs[sign]);
+      // Insert a decimal point after the first digit and add an exponent.
+      it = write_significand(it, significand, significand_size, 1,
+                             decimal_point);
+      if (num_zeros > 0) it = std::fill_n(it, num_zeros, zero);
+      *it++ = static_cast<Char>(exp_char);
+      return write_exponent<Char>(output_exp, it);
+    };
+    return specs.width > 0 ? write_padded<align::right>(out, specs, size, write)
+                           : base_iterator(out, write(reserve(out, size)));
   }
 
-  template <typename T, FMT_ENABLE_IF(!is_integer<T>::value)>
-  auto operator()(T) -> bool {
-    return false;
+  int exp = fp.exponent + significand_size;
+  if (fp.exponent >= 0) {
+    // 1234e5 -> 123400000[.0+]
+    size += to_unsigned(fp.exponent);
+    int num_zeros = fspecs.precision - exp;
+#ifdef FMT_FUZZ
+    if (num_zeros > 5000)
+      throw std::runtime_error("fuzz mode - avoiding excessive cpu use");
+#endif
+    if (fspecs.showpoint) {
+      if (num_zeros <= 0 && fspecs.format != float_format::fixed) num_zeros = 1;
+      if (num_zeros > 0) size += to_unsigned(num_zeros);
+    }
+    return write_padded<align::right>(out, specs, size, [&](iterator it) {
+      if (sign) *it++ = static_cast<Char>(data::signs[sign]);
+      it = write_significand<Char>(it, significand, significand_size);
+      it = std::fill_n(it, fp.exponent, zero);
+      if (!fspecs.showpoint) return it;
+      *it++ = decimal_point;
+      return num_zeros > 0 ? std::fill_n(it, num_zeros, zero) : it;
+    });
+  } else if (exp > 0) {
+    // 1234e-2 -> 12.34[0+]
+    int num_zeros = fspecs.showpoint ? fspecs.precision - significand_size : 0;
+    size += 1 + to_unsigned(num_zeros > 0 ? num_zeros : 0);
+    return write_padded<align::right>(out, specs, size, [&](iterator it) {
+      if (sign) *it++ = static_cast<Char>(data::signs[sign]);
+      it = write_significand(it, significand, significand_size, exp,
+                             decimal_point);
+      return num_zeros > 0 ? std::fill_n(it, num_zeros, zero) : it;
+    });
   }
-};
+  // 1234e-6 -> 0.001234
+  int num_zeros = -exp;
+  if (significand_size == 0 && fspecs.precision >= 0 &&
+      fspecs.precision < num_zeros) {
+    num_zeros = fspecs.precision;
+  }
+  size += 2 + to_unsigned(num_zeros);
+  return write_padded<align::right>(out, specs, size, [&](iterator it) {
+    if (sign) *it++ = static_cast<Char>(data::signs[sign]);
+    *it++ = zero;
+    if (num_zeros == 0 && significand_size == 0 && !fspecs.showpoint) return it;
+    *it++ = decimal_point;
+    it = std::fill_n(it, num_zeros, zero);
+    return write_significand<Char>(it, significand, significand_size);
+  });
+}
 
-template <typename Char, typename OutputIt, typename T>
-FMT_CONSTEXPR FMT_INLINE auto write_int(OutputIt out, write_int_arg<T> arg,
-                                        const format_specs<Char>& specs,
-                                        locale_ref) -> OutputIt {
-  static_assert(std::is_same<T, uint32_or_64_or_128_t<T>>::value, "");
-  auto abs_value = arg.abs_value;
-  auto prefix = arg.prefix;
-  switch (specs.type) {
-  case presentation_type::none:
-  case presentation_type::dec: {
-    auto num_digits = count_digits(abs_value);
-    return write_int(
-        out, num_digits, prefix, specs, [=](reserve_iterator<OutputIt> it) {
-          return format_decimal<Char>(it, abs_value, num_digits).end;
-        });
+template <typename Char, typename OutputIt, typename T,
+          FMT_ENABLE_IF(std::is_floating_point<T>::value)>
+OutputIt write(OutputIt out, T value, basic_format_specs<Char> specs,
+               locale_ref loc = {}) {
+  if (const_check(!is_supported_floating_point(value))) return out;
+  float_specs fspecs = parse_float_type_spec(specs);
+  fspecs.sign = specs.sign;
+  if (std::signbit(value)) {  // value < 0 is false for NaN so use signbit.
+    fspecs.sign = sign::minus;
+    value = -value;
+  } else if (fspecs.sign == sign::minus) {
+    fspecs.sign = sign::none;
   }
-  case presentation_type::hex_lower:
-  case presentation_type::hex_upper: {
-    bool upper = specs.type == presentation_type::hex_upper;
-    if (specs.alt)
-      prefix_append(prefix, unsigned(upper ? 'X' : 'x') << 8 | '0');
-    int num_digits = count_digits<4>(abs_value);
-    return write_int(
-        out, num_digits, prefix, specs, [=](reserve_iterator<OutputIt> it) {
-          return format_uint<4, Char>(it, abs_value, num_digits, upper);
-        });
+
+  if (!std::isfinite(value))
+    return write_nonfinite(out, std::isinf(value), specs, fspecs);
+
+  if (specs.align == align::numeric && fspecs.sign) {
+    auto it = reserve(out, 1);
+    *it++ = static_cast<Char>(data::signs[fspecs.sign]);
+    out = base_iterator(out, it);
+    fspecs.sign = sign::none;
+    if (specs.width != 0) --specs.width;
   }
-  case presentation_type::bin_lower:
-  case presentation_type::bin_upper: {
-    bool upper = specs.type == presentation_type::bin_upper;
-    if (specs.alt)
-      prefix_append(prefix, unsigned(upper ? 'B' : 'b') << 8 | '0');
-    int num_digits = count_digits<1>(abs_value);
-    return write_int(out, num_digits, prefix, specs,
-                     [=](reserve_iterator<OutputIt> it) {
-                       return format_uint<1, Char>(it, abs_value, num_digits);
-                     });
+
+  memory_buffer buffer;
+  if (fspecs.format == float_format::hex) {
+    if (fspecs.sign) buffer.push_back(data::signs[fspecs.sign]);
+    snprintf_float(promote_float(value), specs.precision, fspecs, buffer);
+    return write_bytes(out, {buffer.data(), buffer.size()}, specs);
   }
-  case presentation_type::oct: {
-    int num_digits = count_digits<3>(abs_value);
-    // Octal prefix '0' is counted as a digit, so only add it if precision
-    // is not greater than the number of digits.
-    if (specs.alt && specs.precision <= num_digits && abs_value != 0)
-      prefix_append(prefix, '0');
-    return write_int(out, num_digits, prefix, specs,
-                     [=](reserve_iterator<OutputIt> it) {
-                       return format_uint<3, Char>(it, abs_value, num_digits);
-                     });
-  }
-  case presentation_type::chr:
-    return write_char(out, static_cast<Char>(abs_value), specs);
-  default:
-    throw_format_error("invalid format specifier");
+  int precision = specs.precision >= 0 || !specs.type ? specs.precision : 6;
+  if (fspecs.format == float_format::exp) {
+    if (precision == max_value<int>())
+      FMT_THROW(format_error("number is too big"));
+    else
+      ++precision;
   }
-  return out;
-}
-template <typename Char, typename OutputIt, typename T>
-FMT_CONSTEXPR FMT_NOINLINE auto write_int_noinline(
-    OutputIt out, write_int_arg<T> arg, const format_specs<Char>& specs,
-    locale_ref loc) -> OutputIt {
-  return write_int(out, arg, specs, loc);
+  if (const_check(std::is_same<T, float>())) fspecs.binary32 = true;
+  fspecs.use_grisu = is_fast_float<T>();
+  int exp = format_float(promote_float(value), precision, fspecs, buffer);
+  fspecs.precision = precision;
+  Char point =
+      fspecs.locale ? decimal_point<Char>(loc) : static_cast<Char>('.');
+  auto fp = big_decimal_fp{buffer.data(), static_cast<int>(buffer.size()), exp};
+  return write_float(out, fp, specs, fspecs, point);
 }
+
 template <typename Char, typename OutputIt, typename T,
-          FMT_ENABLE_IF(is_integral<T>::value &&
-                        !std::is_same<T, bool>::value &&
-                        std::is_same<OutputIt, buffer_appender<Char>>::value)>
-FMT_CONSTEXPR FMT_INLINE auto write(OutputIt out, T value,
-                                    const format_specs<Char>& specs,
-                                    locale_ref loc) -> OutputIt {
-  if (specs.localized && write_loc(out, value, specs, loc)) return out;
-  return write_int_noinline(out, make_write_int_arg(value, specs.sign), specs,
-                            loc);
-}
-// An inlined version of write used in format string compilation.
-template <typename Char, typename OutputIt, typename T,
-          FMT_ENABLE_IF(is_integral<T>::value &&
-                        !std::is_same<T, bool>::value &&
-                        !std::is_same<OutputIt, buffer_appender<Char>>::value)>
-FMT_CONSTEXPR FMT_INLINE auto write(OutputIt out, T value,
-                                    const format_specs<Char>& specs,
-                                    locale_ref loc) -> OutputIt {
-  if (specs.localized && write_loc(out, value, specs, loc)) return out;
-  return write_int(out, make_write_int_arg(value, specs.sign), specs, loc);
-}
+          FMT_ENABLE_IF(is_fast_float<T>::value)>
+OutputIt write(OutputIt out, T value) {
+  if (const_check(!is_supported_floating_point(value))) return out;
 
-// An output iterator that counts the number of objects written to it and
-// discards them.
-class counting_iterator {
- private:
-  size_t count_;
+  using floaty = conditional_t<std::is_same<T, long double>::value, double, T>;
+  using uint = typename dragonbox::float_info<floaty>::carrier_uint;
+  auto bits = bit_cast<uint>(value);
 
- public:
-  using iterator_category = std::output_iterator_tag;
-  using difference_type = std::ptrdiff_t;
-  using pointer = void;
-  using reference = void;
-  FMT_UNCHECKED_ITERATOR(counting_iterator);
+  auto fspecs = float_specs();
+  auto sign_bit = bits & (uint(1) << (num_bits<uint>() - 1));
+  if (sign_bit != 0) {
+    fspecs.sign = sign::minus;
+    value = -value;
+  }
 
-  struct value_type {
-    template <typename T> FMT_CONSTEXPR void operator=(const T&) {}
-  };
+  static const auto specs = basic_format_specs<Char>();
+  uint mask = exponent_mask<floaty>();
+  if ((bits & mask) == mask)
+    return write_nonfinite(out, std::isinf(value), specs, fspecs);
 
-  FMT_CONSTEXPR counting_iterator() : count_(0) {}
+  auto dec = dragonbox::to_decimal(static_cast<floaty>(value));
+  return write_float(out, dec, specs, fspecs, static_cast<Char>('.'));
+}
 
-  FMT_CONSTEXPR size_t count() const { return count_; }
+template <typename Char, typename OutputIt, typename T,
+          FMT_ENABLE_IF(std::is_floating_point<T>::value &&
+                        !is_fast_float<T>::value)>
+inline OutputIt write(OutputIt out, T value) {
+  return write(out, value, basic_format_specs<Char>());
+}
 
-  FMT_CONSTEXPR counting_iterator& operator++() {
-    ++count_;
-    return *this;
-  }
-  FMT_CONSTEXPR counting_iterator operator++(int) {
-    auto it = *this;
-    ++*this;
+template <typename Char, typename OutputIt>
+OutputIt write_char(OutputIt out, Char value,
+                    const basic_format_specs<Char>& specs) {
+  using iterator = remove_reference_t<decltype(reserve(out, 0))>;
+  return write_padded(out, specs, 1, [=](iterator it) {
+    *it++ = value;
     return it;
-  }
+  });
+}
 
-  FMT_CONSTEXPR friend counting_iterator operator+(counting_iterator it,
-                                                   difference_type n) {
-    it.count_ += static_cast<size_t>(n);
-    return it;
-  }
+template <typename Char, typename OutputIt, typename UIntPtr>
+OutputIt write_ptr(OutputIt out, UIntPtr value,
+                   const basic_format_specs<Char>* specs) {
+  int num_digits = count_digits<4>(value);
+  auto size = to_unsigned(num_digits) + size_t(2);
+  using iterator = remove_reference_t<decltype(reserve(out, 0))>;
+  auto write = [=](iterator it) {
+    *it++ = static_cast<Char>('0');
+    *it++ = static_cast<Char>('x');
+    return format_uint<4, Char>(it, value, num_digits);
+  };
+  return specs ? write_padded<align::right>(out, *specs, size, write)
+               : base_iterator(out, write(reserve(out, size)));
+}
 
-  FMT_CONSTEXPR value_type operator*() const { return {}; }
-};
+template <typename T> struct is_integral : std::is_integral<T> {};
+template <> struct is_integral<int128_t> : std::true_type {};
+template <> struct is_integral<uint128_t> : std::true_type {};
 
 template <typename Char, typename OutputIt>
-FMT_CONSTEXPR auto write(OutputIt out, basic_string_view<Char> s,
-                         const format_specs<Char>& specs) -> OutputIt {
-  auto data = s.data();
-  auto size = s.size();
-  if (specs.precision >= 0 && to_unsigned(specs.precision) < size)
-    size = code_point_index(s, to_unsigned(specs.precision));
-  bool is_debug = specs.type == presentation_type::debug;
-  size_t width = 0;
-  if (specs.width != 0) {
-    if (is_debug)
-      width = write_escaped_string(counting_iterator{}, s).count();
-    else
-      width = compute_width(basic_string_view<Char>(data, size));
-  }
-  return write_padded(out, specs, size, width,
-                      [=](reserve_iterator<OutputIt> it) {
-                        if (is_debug) return write_escaped_string(it, s);
-                        return copy_str<Char>(data, data + size, it);
-                      });
+OutputIt write(OutputIt out, monostate) {
+  FMT_ASSERT(false, "");
+  return out;
 }
-template <typename Char, typename OutputIt>
-FMT_CONSTEXPR auto write(OutputIt out,
-                         basic_string_view<type_identity_t<Char>> s,
-                         const format_specs<Char>& specs, locale_ref)
-    -> OutputIt {
-  return write(out, s, specs);
+
+template <typename Char, typename OutputIt,
+          FMT_ENABLE_IF(!std::is_same<Char, char>::value)>
+OutputIt write(OutputIt out, string_view value) {
+  auto it = reserve(out, value.size());
+  it = copy_str<Char>(value.begin(), value.end(), it);
+  return base_iterator(out, it);
 }
+
 template <typename Char, typename OutputIt>
-FMT_CONSTEXPR auto write(OutputIt out, const Char* s,
-                         const format_specs<Char>& specs, locale_ref)
-    -> OutputIt {
-  if (specs.type == presentation_type::pointer)
-    return write_ptr<Char>(out, bit_cast<uintptr_t>(s), &specs);
-  if (!s) throw_format_error("string pointer is null");
-  return write(out, basic_string_view<Char>(s), specs, {});
+OutputIt write(OutputIt out, basic_string_view<Char> value) {
+  auto it = reserve(out, value.size());
+  it = std::copy(value.begin(), value.end(), it);
+  return base_iterator(out, it);
+}
+
+template <typename Char>
+buffer_appender<Char> write(buffer_appender<Char> out,
+                            basic_string_view<Char> value) {
+  get_container(out).append(value.begin(), value.end());
+  return out;
 }
 
 template <typename Char, typename OutputIt, typename T,
           FMT_ENABLE_IF(is_integral<T>::value &&
                         !std::is_same<T, bool>::value &&
                         !std::is_same<T, Char>::value)>
-FMT_CONSTEXPR auto write(OutputIt out, T value) -> OutputIt {
+OutputIt write(OutputIt out, T value) {
   auto abs_value = static_cast<uint32_or_64_or_128_t<T>>(value);
   bool negative = is_negative(value);
   // Don't do -abs_value since it trips unsigned-integer-overflow sanitizer.
@@ -2377,1624 +2052,1283 @@ FMT_CONSTEXPR auto write(OutputIt out, T value) -> OutputIt {
   return base_iterator(out, it);
 }
 
-// DEPRECATED!
-template <typename Char>
-FMT_CONSTEXPR auto parse_align(const Char* begin, const Char* end,
-                               format_specs<Char>& specs) -> const Char* {
-  FMT_ASSERT(begin != end, "");
-  auto align = align::none;
-  auto p = begin + code_point_length(begin);
-  if (end - p <= 0) p = begin;
-  for (;;) {
-    switch (to_ascii(*p)) {
-    case '<':
-      align = align::left;
-      break;
-    case '>':
-      align = align::right;
-      break;
-    case '^':
-      align = align::center;
-      break;
-    }
-    if (align != align::none) {
-      if (p != begin) {
-        auto c = *begin;
-        if (c == '}') return begin;
-        if (c == '{') {
-          throw_format_error("invalid fill character '{'");
-          return begin;
-        }
-        specs.fill = {begin, to_unsigned(p - begin)};
-        begin = p + 1;
-      } else {
-        ++begin;
-      }
-      break;
-    } else if (p == begin) {
-      break;
-    }
-    p = begin;
+template <typename Char, typename OutputIt>
+OutputIt write(OutputIt out, bool value) {
+  return write<Char>(out, string_view(value ? "true" : "false"));
+}
+
+template <typename Char, typename OutputIt>
+OutputIt write(OutputIt out, Char value) {
+  auto it = reserve(out, 1);
+  *it++ = value;
+  return base_iterator(out, it);
+}
+
+template <typename Char, typename OutputIt>
+OutputIt write(OutputIt out, const Char* value) {
+  if (!value) {
+    FMT_THROW(format_error("string pointer is null"));
+  } else {
+    auto length = std::char_traits<Char>::length(value);
+    out = write(out, basic_string_view<Char>(value, length));
   }
-  specs.align = align;
-  return begin;
+  return out;
 }
 
-// A floating-point presentation format.
-enum class float_format : unsigned char {
-  general,  // General: exponent notation or fixed point based on magnitude.
-  exp,      // Exponent notation with the default precision of 6, e.g. 1.2e-3.
-  fixed,    // Fixed point with the default precision of 6, e.g. 0.0012.
-  hex
-};
+template <typename Char, typename OutputIt>
+OutputIt write(OutputIt out, const void* value) {
+  return write_ptr<Char>(out, to_uintptr(value), nullptr);
+}
 
-struct float_specs {
-  int precision;
-  float_format format : 8;
-  sign_t sign : 8;
-  bool upper : 1;
-  bool locale : 1;
-  bool binary32 : 1;
-  bool showpoint : 1;
+template <typename Char, typename OutputIt, typename T>
+auto write(OutputIt out, const T& value) -> typename std::enable_if<
+    mapped_type_constant<T, basic_format_context<OutputIt, Char>>::value ==
+        type::custom_type,
+    OutputIt>::type {
+  using context_type = basic_format_context<OutputIt, Char>;
+  using formatter_type =
+      conditional_t<has_formatter<T, context_type>::value,
+                    typename context_type::template formatter_type<T>,
+                    fallback_formatter<T, Char>>;
+  context_type ctx(out, {}, {});
+  return formatter_type().format(value, ctx);
+}
+
+// An argument visitor that formats the argument and writes it via the output
+// iterator. It's a class and not a generic lambda for compatibility with C++11.
+template <typename OutputIt, typename Char> struct default_arg_formatter {
+  using context = basic_format_context<OutputIt, Char>;
+
+  OutputIt out;
+  basic_format_args<context> args;
+  locale_ref loc;
+
+  template <typename T> OutputIt operator()(T value) {
+    return write<Char>(out, value);
+  }
+
+  OutputIt operator()(typename basic_format_arg<context>::handle handle) {
+    basic_format_parse_context<Char> parse_ctx({});
+    basic_format_context<OutputIt, Char> format_ctx(out, args, loc);
+    handle.format(parse_ctx, format_ctx);
+    return format_ctx.out();
+  }
 };
 
-template <typename ErrorHandler = error_handler, typename Char>
-FMT_CONSTEXPR auto parse_float_type_spec(const format_specs<Char>& specs,
-                                         ErrorHandler&& eh = {})
-    -> float_specs {
-  auto result = float_specs();
-  result.showpoint = specs.alt;
-  result.locale = specs.localized;
-  switch (specs.type) {
-  case presentation_type::none:
-    result.format = float_format::general;
-    break;
-  case presentation_type::general_upper:
-    result.upper = true;
-    FMT_FALLTHROUGH;
-  case presentation_type::general_lower:
-    result.format = float_format::general;
-    break;
-  case presentation_type::exp_upper:
-    result.upper = true;
-    FMT_FALLTHROUGH;
-  case presentation_type::exp_lower:
-    result.format = float_format::exp;
-    result.showpoint |= specs.precision != 0;
-    break;
-  case presentation_type::fixed_upper:
-    result.upper = true;
-    FMT_FALLTHROUGH;
-  case presentation_type::fixed_lower:
-    result.format = float_format::fixed;
-    result.showpoint |= specs.precision != 0;
-    break;
-  case presentation_type::hexfloat_upper:
-    result.upper = true;
-    FMT_FALLTHROUGH;
-  case presentation_type::hexfloat_lower:
-    result.format = float_format::hex;
-    break;
-  default:
-    eh.on_error("invalid format specifier");
-    break;
+template <typename OutputIt, typename Char,
+          typename ErrorHandler = error_handler>
+class arg_formatter_base {
+ public:
+  using iterator = OutputIt;
+  using char_type = Char;
+  using format_specs = basic_format_specs<Char>;
+
+ private:
+  iterator out_;
+  locale_ref locale_;
+  format_specs* specs_;
+
+  // Attempts to reserve space for n extra characters in the output range.
+  // Returns a pointer to the reserved range or a reference to out_.
+  auto reserve(size_t n) -> decltype(detail::reserve(out_, n)) {
+    return detail::reserve(out_, n);
   }
-  return result;
-}
 
-template <typename Char, typename OutputIt>
-FMT_CONSTEXPR20 auto write_nonfinite(OutputIt out, bool isnan,
-                                     format_specs<Char> specs,
-                                     const float_specs& fspecs) -> OutputIt {
-  auto str =
-      isnan ? (fspecs.upper ? "NAN" : "nan") : (fspecs.upper ? "INF" : "inf");
-  constexpr size_t str_size = 3;
-  auto sign = fspecs.sign;
-  auto size = str_size + (sign ? 1 : 0);
-  // Replace '0'-padding with space for non-finite values.
-  const bool is_zero_fill =
-      specs.fill.size() == 1 && *specs.fill.data() == static_cast<Char>('0');
-  if (is_zero_fill) specs.fill[0] = static_cast<Char>(' ');
-  return write_padded(out, specs, size, [=](reserve_iterator<OutputIt> it) {
-    if (sign) *it++ = detail::sign<Char>(sign);
-    return copy_str<Char>(str, str + str_size, it);
-  });
-}
+  using reserve_iterator = remove_reference_t<decltype(
+      detail::reserve(std::declval<iterator&>(), 0))>;
 
-// A decimal floating-point number significand * pow(10, exp).
-struct big_decimal_fp {
-  const char* significand;
-  int significand_size;
-  int exponent;
-};
+  template <typename T> void write_int(T value, const format_specs& spec) {
+    using uint_type = uint32_or_64_or_128_t<T>;
+    int_writer<iterator, Char, uint_type> w(out_, locale_, value, spec);
+    handle_int_type_spec(spec.type, w);
+    out_ = w.out;
+  }
 
-constexpr auto get_significand_size(const big_decimal_fp& f) -> int {
-  return f.significand_size;
-}
-template <typename T>
-inline auto get_significand_size(const dragonbox::decimal_fp<T>& f) -> int {
-  return count_digits(f.significand);
-}
+  void write(char value) {
+    auto&& it = reserve(1);
+    *it++ = value;
+  }
 
-template <typename Char, typename OutputIt>
-constexpr auto write_significand(OutputIt out, const char* significand,
-                                 int significand_size) -> OutputIt {
-  return copy_str<Char>(significand, significand + significand_size, out);
-}
-template <typename Char, typename OutputIt, typename UInt>
-inline auto write_significand(OutputIt out, UInt significand,
-                              int significand_size) -> OutputIt {
-  return format_decimal<Char>(out, significand, significand_size).end;
-}
-template <typename Char, typename OutputIt, typename T, typename Grouping>
-FMT_CONSTEXPR20 auto write_significand(OutputIt out, T significand,
-                                       int significand_size, int exponent,
-                                       const Grouping& grouping) -> OutputIt {
-  if (!grouping.has_separator()) {
-    out = write_significand<Char>(out, significand, significand_size);
-    return detail::fill_n(out, exponent, static_cast<Char>('0'));
+  template <typename Ch, FMT_ENABLE_IF(std::is_same<Ch, Char>::value)>
+  void write(Ch value) {
+    out_ = detail::write<Char>(out_, value);
   }
-  auto buffer = memory_buffer();
-  write_significand<char>(appender(buffer), significand, significand_size);
-  detail::fill_n(appender(buffer), exponent, '0');
-  return grouping.apply(out, string_view(buffer.data(), buffer.size()));
-}
 
-template <typename Char, typename UInt,
-          FMT_ENABLE_IF(std::is_integral<UInt>::value)>
-inline auto write_significand(Char* out, UInt significand, int significand_size,
-                              int integral_size, Char decimal_point) -> Char* {
-  if (!decimal_point)
-    return format_decimal(out, significand, significand_size).end;
-  out += significand_size + 1;
-  Char* end = out;
-  int floating_size = significand_size - integral_size;
-  for (int i = floating_size / 2; i > 0; --i) {
-    out -= 2;
-    copy2(out, digits2(static_cast<std::size_t>(significand % 100)));
-    significand /= 100;
+  void write(string_view value) {
+    auto&& it = reserve(value.size());
+    it = copy_str<Char>(value.begin(), value.end(), it);
   }
-  if (floating_size % 2 != 0) {
-    *--out = static_cast<Char>('0' + significand % 10);
-    significand /= 10;
+  void write(wstring_view value) {
+    static_assert(std::is_same<Char, wchar_t>::value, "");
+    auto&& it = reserve(value.size());
+    it = std::copy(value.begin(), value.end(), it);
   }
-  *--out = decimal_point;
-  format_decimal(out - integral_size, significand, integral_size);
-  return end;
-}
 
-template <typename OutputIt, typename UInt, typename Char,
-          FMT_ENABLE_IF(!std::is_pointer<remove_cvref_t<OutputIt>>::value)>
-inline auto write_significand(OutputIt out, UInt significand,
-                              int significand_size, int integral_size,
-                              Char decimal_point) -> OutputIt {
-  // Buffer is large enough to hold digits (digits10 + 1) and a decimal point.
-  Char buffer[digits10<UInt>() + 2];
-  auto end = write_significand(buffer, significand, significand_size,
-                               integral_size, decimal_point);
-  return detail::copy_str_noinline<Char>(buffer, end, out);
-}
+  template <typename Ch>
+  void write(const Ch* s, size_t size, const format_specs& specs) {
+    auto width = specs.width != 0
+                     ? count_code_points(basic_string_view<Ch>(s, size))
+                     : 0;
+    out_ = write_padded(out_, specs, size, width, [=](reserve_iterator it) {
+      return copy_str<Char>(s, s + size, it);
+    });
+  }
 
-template <typename OutputIt, typename Char>
-FMT_CONSTEXPR auto write_significand(OutputIt out, const char* significand,
-                                     int significand_size, int integral_size,
-                                     Char decimal_point) -> OutputIt {
-  out = detail::copy_str_noinline<Char>(significand,
-                                        significand + integral_size, out);
-  if (!decimal_point) return out;
-  *out++ = decimal_point;
-  return detail::copy_str_noinline<Char>(significand + integral_size,
-                                         significand + significand_size, out);
-}
+  template <typename Ch>
+  void write(basic_string_view<Ch> s, const format_specs& specs = {}) {
+    out_ = detail::write(out_, s, specs);
+  }
 
-template <typename OutputIt, typename Char, typename T, typename Grouping>
-FMT_CONSTEXPR20 auto write_significand(OutputIt out, T significand,
-                                       int significand_size, int integral_size,
-                                       Char decimal_point,
-                                       const Grouping& grouping) -> OutputIt {
-  if (!grouping.has_separator()) {
-    return write_significand(out, significand, significand_size, integral_size,
-                             decimal_point);
+  void write_pointer(const void* p) {
+    out_ = write_ptr<char_type>(out_, to_uintptr(p), specs_);
   }
-  auto buffer = basic_memory_buffer<Char>();
-  write_significand(buffer_appender<Char>(buffer), significand,
-                    significand_size, integral_size, decimal_point);
-  grouping.apply(
-      out, basic_string_view<Char>(buffer.data(), to_unsigned(integral_size)));
-  return detail::copy_str_noinline<Char>(buffer.data() + integral_size,
-                                         buffer.end(), out);
-}
-
-template <typename OutputIt, typename DecimalFP, typename Char,
-          typename Grouping = digit_grouping<Char>>
-FMT_CONSTEXPR20 auto do_write_float(OutputIt out, const DecimalFP& f,
-                                    const format_specs<Char>& specs,
-                                    float_specs fspecs, locale_ref loc)
-    -> OutputIt {
-  auto significand = f.significand;
-  int significand_size = get_significand_size(f);
-  const Char zero = static_cast<Char>('0');
-  auto sign = fspecs.sign;
-  size_t size = to_unsigned(significand_size) + (sign ? 1 : 0);
-  using iterator = reserve_iterator<OutputIt>;
 
-  Char decimal_point =
-      fspecs.locale ? detail::decimal_point<Char>(loc) : static_cast<Char>('.');
+  struct char_spec_handler : ErrorHandler {
+    arg_formatter_base& formatter;
+    Char value;
 
-  int output_exp = f.exponent + significand_size - 1;
-  auto use_exp_format = [=]() {
-    if (fspecs.format == float_format::exp) return true;
-    if (fspecs.format != float_format::general) return false;
-    // Use the fixed notation if the exponent is in [exp_lower, exp_upper),
-    // e.g. 0.0001 instead of 1e-04. Otherwise use the exponent notation.
-    const int exp_lower = -4, exp_upper = 16;
-    return output_exp < exp_lower ||
-           output_exp >= (fspecs.precision > 0 ? fspecs.precision : exp_upper);
-  };
-  if (use_exp_format()) {
-    int num_zeros = 0;
-    if (fspecs.showpoint) {
-      num_zeros = fspecs.precision - significand_size;
-      if (num_zeros < 0) num_zeros = 0;
-      size += to_unsigned(num_zeros);
-    } else if (significand_size == 1) {
-      decimal_point = Char();
+    char_spec_handler(arg_formatter_base& f, Char val)
+        : formatter(f), value(val) {}
+
+    void on_int() {
+      // char is only formatted as int if there are specs.
+      formatter.write_int(static_cast<int>(value), *formatter.specs_);
     }
-    auto abs_output_exp = output_exp >= 0 ? output_exp : -output_exp;
-    int exp_digits = 2;
-    if (abs_output_exp >= 100) exp_digits = abs_output_exp >= 1000 ? 4 : 3;
+    void on_char() {
+      if (formatter.specs_)
+        formatter.out_ = write_char(formatter.out_, value, *formatter.specs_);
+      else
+        formatter.write(value);
+    }
+  };
 
-    size += to_unsigned((decimal_point ? 1 : 0) + 2 + exp_digits);
-    char exp_char = fspecs.upper ? 'E' : 'e';
-    auto write = [=](iterator it) {
-      if (sign) *it++ = detail::sign<Char>(sign);
-      // Insert a decimal point after the first digit and add an exponent.
-      it = write_significand(it, significand, significand_size, 1,
-                             decimal_point);
-      if (num_zeros > 0) it = detail::fill_n(it, num_zeros, zero);
-      *it++ = static_cast<Char>(exp_char);
-      return write_exponent<Char>(output_exp, it);
-    };
-    return specs.width > 0 ? write_padded<align::right>(out, specs, size, write)
-                           : base_iterator(out, write(reserve(out, size)));
+  struct cstring_spec_handler : error_handler {
+    arg_formatter_base& formatter;
+    const Char* value;
+
+    cstring_spec_handler(arg_formatter_base& f, const Char* val)
+        : formatter(f), value(val) {}
+
+    void on_string() { formatter.write(value); }
+    void on_pointer() { formatter.write_pointer(value); }
+  };
+
+ protected:
+  iterator out() { return out_; }
+  format_specs* specs() { return specs_; }
+
+  void write(bool value) {
+    if (specs_)
+      write(string_view(value ? "true" : "false"), *specs_);
+    else
+      out_ = detail::write<Char>(out_, value);
   }
 
-  int exp = f.exponent + significand_size;
-  if (f.exponent >= 0) {
-    // 1234e5 -> 123400000[.0+]
-    size += to_unsigned(f.exponent);
-    int num_zeros = fspecs.precision - exp;
-    abort_fuzzing_if(num_zeros > 5000);
-    if (fspecs.showpoint) {
-      ++size;
-      if (num_zeros <= 0 && fspecs.format != float_format::fixed) num_zeros = 0;
-      if (num_zeros > 0) size += to_unsigned(num_zeros);
+  void write(const Char* value) {
+    if (!value) {
+      FMT_THROW(format_error("string pointer is null"));
+    } else {
+      auto length = std::char_traits<char_type>::length(value);
+      basic_string_view<char_type> sv(value, length);
+      specs_ ? write(sv, *specs_) : write(sv);
     }
-    auto grouping = Grouping(loc, fspecs.locale);
-    size += to_unsigned(grouping.count_separators(exp));
-    return write_padded<align::right>(out, specs, size, [&](iterator it) {
-      if (sign) *it++ = detail::sign<Char>(sign);
-      it = write_significand<Char>(it, significand, significand_size,
-                                   f.exponent, grouping);
-      if (!fspecs.showpoint) return it;
-      *it++ = decimal_point;
-      return num_zeros > 0 ? detail::fill_n(it, num_zeros, zero) : it;
-    });
-  } else if (exp > 0) {
-    // 1234e-2 -> 12.34[0+]
-    int num_zeros = fspecs.showpoint ? fspecs.precision - significand_size : 0;
-    size += 1 + to_unsigned(num_zeros > 0 ? num_zeros : 0);
-    auto grouping = Grouping(loc, fspecs.locale);
-    size += to_unsigned(grouping.count_separators(exp));
-    return write_padded<align::right>(out, specs, size, [&](iterator it) {
-      if (sign) *it++ = detail::sign<Char>(sign);
-      it = write_significand(it, significand, significand_size, exp,
-                             decimal_point, grouping);
-      return num_zeros > 0 ? detail::fill_n(it, num_zeros, zero) : it;
-    });
-  }
-  // 1234e-6 -> 0.001234
-  int num_zeros = -exp;
-  if (significand_size == 0 && fspecs.precision >= 0 &&
-      fspecs.precision < num_zeros) {
-    num_zeros = fspecs.precision;
   }
-  bool pointy = num_zeros != 0 || significand_size != 0 || fspecs.showpoint;
-  size += 1 + (pointy ? 1 : 0) + to_unsigned(num_zeros);
-  return write_padded<align::right>(out, specs, size, [&](iterator it) {
-    if (sign) *it++ = detail::sign<Char>(sign);
-    *it++ = zero;
-    if (!pointy) return it;
-    *it++ = decimal_point;
-    it = detail::fill_n(it, num_zeros, zero);
-    return write_significand<Char>(it, significand, significand_size);
-  });
-}
 
-template <typename Char> class fallback_digit_grouping {
  public:
-  constexpr fallback_digit_grouping(locale_ref, bool) {}
+  arg_formatter_base(OutputIt out, format_specs* s, locale_ref loc)
+      : out_(out), locale_(loc), specs_(s) {}
 
-  constexpr bool has_separator() const { return false; }
+  iterator operator()(monostate) {
+    FMT_ASSERT(false, "invalid argument type");
+    return out_;
+  }
 
-  constexpr int count_separators(int) const { return 0; }
+  template <typename T, FMT_ENABLE_IF(is_integral<T>::value)>
+  FMT_INLINE iterator operator()(T value) {
+    if (specs_)
+      write_int(value, *specs_);
+    else
+      out_ = detail::write<Char>(out_, value);
+    return out_;
+  }
 
-  template <typename Out, typename C>
-  constexpr Out apply(Out out, basic_string_view<C>) const {
-    return out;
+  iterator operator()(Char value) {
+    handle_char_specs(specs_,
+                      char_spec_handler(*this, static_cast<Char>(value)));
+    return out_;
+  }
+
+  iterator operator()(bool value) {
+    if (specs_ && specs_->type) return (*this)(value ? 1 : 0);
+    write(value != 0);
+    return out_;
+  }
+
+  template <typename T, FMT_ENABLE_IF(std::is_floating_point<T>::value)>
+  iterator operator()(T value) {
+    auto specs = specs_ ? *specs_ : format_specs();
+    if (const_check(is_supported_floating_point(value)))
+      out_ = detail::write(out_, value, specs, locale_);
+    else
+      FMT_ASSERT(false, "unsupported float argument type");
+    return out_;
+  }
+
+  iterator operator()(const Char* value) {
+    if (!specs_) return write(value), out_;
+    handle_cstring_type_spec(specs_->type, cstring_spec_handler(*this, value));
+    return out_;
+  }
+
+  iterator operator()(basic_string_view<Char> value) {
+    if (specs_) {
+      check_string_type_spec(specs_->type, error_handler());
+      write(value, *specs_);
+    } else {
+      write(value);
+    }
+    return out_;
+  }
+
+  iterator operator()(const void* value) {
+    if (specs_) check_pointer_type_spec(specs_->type, error_handler());
+    write_pointer(value);
+    return out_;
   }
 };
 
-template <typename OutputIt, typename DecimalFP, typename Char>
-FMT_CONSTEXPR20 auto write_float(OutputIt out, const DecimalFP& f,
-                                 const format_specs<Char>& specs,
-                                 float_specs fspecs, locale_ref loc)
-    -> OutputIt {
-  if (is_constant_evaluated()) {
-    return do_write_float<OutputIt, DecimalFP, Char,
-                          fallback_digit_grouping<Char>>(out, f, specs, fspecs,
-                                                         loc);
-  } else {
-    return do_write_float(out, f, specs, fspecs, loc);
+/** The default argument formatter. */
+template <typename OutputIt, typename Char>
+class arg_formatter : public arg_formatter_base<OutputIt, Char> {
+ private:
+  using char_type = Char;
+  using base = arg_formatter_base<OutputIt, Char>;
+  using context_type = basic_format_context<OutputIt, Char>;
+
+  context_type& ctx_;
+  basic_format_parse_context<char_type>* parse_ctx_;
+  const Char* ptr_;
+
+ public:
+  using iterator = typename base::iterator;
+  using format_specs = typename base::format_specs;
+
+  /**
+    \rst
+    Constructs an argument formatter object.
+    *ctx* is a reference to the formatting context,
+    *specs* contains format specifier information for standard argument types.
+    \endrst
+   */
+  explicit arg_formatter(
+      context_type& ctx,
+      basic_format_parse_context<char_type>* parse_ctx = nullptr,
+      format_specs* specs = nullptr, const Char* ptr = nullptr)
+      : base(ctx.out(), specs, ctx.locale()),
+        ctx_(ctx),
+        parse_ctx_(parse_ctx),
+        ptr_(ptr) {}
+
+  using base::operator();
+
+  /** Formats an argument of a user-defined type. */
+  iterator operator()(typename basic_format_arg<context_type>::handle handle) {
+    if (ptr_) advance_to(*parse_ctx_, ptr_);
+    handle.format(*parse_ctx_, ctx_);
+    return ctx_.out();
   }
+};
+
+template <typename Char> FMT_CONSTEXPR bool is_name_start(Char c) {
+  return ('a' <= c && c <= 'z') || ('A' <= c && c <= 'Z') || '_' == c;
 }
 
-template <typename T> constexpr bool isnan(T value) {
-  return !(value >= value);  // std::isnan doesn't support __float128.
+// Parses the range [begin, end) as an unsigned integer. This function assumes
+// that the range is non-empty and the first character is a digit.
+template <typename Char, typename ErrorHandler>
+FMT_CONSTEXPR int parse_nonnegative_int(const Char*& begin, const Char* end,
+                                        ErrorHandler&& eh) {
+  FMT_ASSERT(begin != end && '0' <= *begin && *begin <= '9', "");
+  unsigned value = 0;
+  // Convert to unsigned to prevent a warning.
+  constexpr unsigned max_int = max_value<int>();
+  unsigned big = max_int / 10;
+  do {
+    // Check for overflow.
+    if (value > big) {
+      value = max_int + 1;
+      break;
+    }
+    value = value * 10 + unsigned(*begin - '0');
+    ++begin;
+  } while (begin != end && '0' <= *begin && *begin <= '9');
+  if (value > max_int) eh.on_error("number is too big");
+  return static_cast<int>(value);
 }
 
-template <typename T, typename Enable = void>
-struct has_isfinite : std::false_type {};
+template <typename Context> class custom_formatter {
+ private:
+  using char_type = typename Context::char_type;
+
+  basic_format_parse_context<char_type>& parse_ctx_;
+  Context& ctx_;
+
+ public:
+  explicit custom_formatter(basic_format_parse_context<char_type>& parse_ctx,
+                            Context& ctx)
+      : parse_ctx_(parse_ctx), ctx_(ctx) {}
+
+  void operator()(typename basic_format_arg<Context>::handle h) const {
+    h.format(parse_ctx_, ctx_);
+  }
+
+  template <typename T> void operator()(T) const {}
+};
 
 template <typename T>
-struct has_isfinite<T, enable_if_t<sizeof(std::isfinite(T())) != 0>>
-    : std::true_type {};
-
-template <typename T, FMT_ENABLE_IF(std::is_floating_point<T>::value&&
-                                        has_isfinite<T>::value)>
-FMT_CONSTEXPR20 bool isfinite(T value) {
-  constexpr T inf = T(std::numeric_limits<double>::infinity());
-  if (is_constant_evaluated())
-    return !detail::isnan(value) && value < inf && value > -inf;
-  return std::isfinite(value);
-}
-template <typename T, FMT_ENABLE_IF(!has_isfinite<T>::value)>
-FMT_CONSTEXPR bool isfinite(T value) {
-  T inf = T(std::numeric_limits<double>::infinity());
-  // std::isfinite doesn't support __float128.
-  return !detail::isnan(value) && value < inf && value > -inf;
-}
-
-template <typename T, FMT_ENABLE_IF(is_floating_point<T>::value)>
-FMT_INLINE FMT_CONSTEXPR bool signbit(T value) {
-  if (is_constant_evaluated()) {
-#ifdef __cpp_if_constexpr
-    if constexpr (std::numeric_limits<double>::is_iec559) {
-      auto bits = detail::bit_cast<uint64_t>(static_cast<double>(value));
-      return (bits >> (num_bits<uint64_t>() - 1)) != 0;
-    }
-#endif
+using is_integer =
+    bool_constant<is_integral<T>::value && !std::is_same<T, bool>::value &&
+                  !std::is_same<T, char>::value &&
+                  !std::is_same<T, wchar_t>::value>;
+
+template <typename ErrorHandler> class width_checker {
+ public:
+  explicit FMT_CONSTEXPR width_checker(ErrorHandler& eh) : handler_(eh) {}
+
+  template <typename T, FMT_ENABLE_IF(is_integer<T>::value)>
+  FMT_CONSTEXPR unsigned long long operator()(T value) {
+    if (is_negative(value)) handler_.on_error("negative width");
+    return static_cast<unsigned long long>(value);
   }
-  return std::signbit(static_cast<double>(value));
-}
 
-inline FMT_CONSTEXPR20 void adjust_precision(int& precision, int exp10) {
-  // Adjust fixed precision by exponent because it is relative to decimal
-  // point.
-  if (exp10 > 0 && precision > max_value<int>() - exp10)
-    FMT_THROW(format_error("number is too big"));
-  precision += exp10;
-}
+  template <typename T, FMT_ENABLE_IF(!is_integer<T>::value)>
+  FMT_CONSTEXPR unsigned long long operator()(T) {
+    handler_.on_error("width is not integer");
+    return 0;
+  }
 
-class bigint {
  private:
-  // A bigint is stored as an array of bigits (big digits), with bigit at index
-  // 0 being the least significant one.
-  using bigit = uint32_t;
-  using double_bigit = uint64_t;
-  enum { bigits_capacity = 32 };
-  basic_memory_buffer<bigit, bigits_capacity> bigits_;
-  int exp_;
+  ErrorHandler& handler_;
+};
+
+template <typename ErrorHandler> class precision_checker {
+ public:
+  explicit FMT_CONSTEXPR precision_checker(ErrorHandler& eh) : handler_(eh) {}
 
-  FMT_CONSTEXPR20 bigit operator[](int index) const {
-    return bigits_[to_unsigned(index)];
+  template <typename T, FMT_ENABLE_IF(is_integer<T>::value)>
+  FMT_CONSTEXPR unsigned long long operator()(T value) {
+    if (is_negative(value)) handler_.on_error("negative precision");
+    return static_cast<unsigned long long>(value);
   }
-  FMT_CONSTEXPR20 bigit& operator[](int index) {
-    return bigits_[to_unsigned(index)];
+
+  template <typename T, FMT_ENABLE_IF(!is_integer<T>::value)>
+  FMT_CONSTEXPR unsigned long long operator()(T) {
+    handler_.on_error("precision is not integer");
+    return 0;
   }
 
-  static constexpr const int bigit_bits = num_bits<bigit>();
+ private:
+  ErrorHandler& handler_;
+};
+
+// A format specifier handler that sets fields in basic_format_specs.
+template <typename Char> class specs_setter {
+ public:
+  explicit FMT_CONSTEXPR specs_setter(basic_format_specs<Char>& specs)
+      : specs_(specs) {}
 
-  friend struct formatter<bigint>;
+  FMT_CONSTEXPR specs_setter(const specs_setter& other)
+      : specs_(other.specs_) {}
 
-  FMT_CONSTEXPR20 void subtract_bigits(int index, bigit other, bigit& borrow) {
-    auto result = static_cast<double_bigit>((*this)[index]) - other - borrow;
-    (*this)[index] = static_cast<bigit>(result);
-    borrow = static_cast<bigit>(result >> (bigit_bits * 2 - 1));
+  FMT_CONSTEXPR void on_align(align_t align) { specs_.align = align; }
+  FMT_CONSTEXPR void on_fill(basic_string_view<Char> fill) {
+    specs_.fill = fill;
   }
+  FMT_CONSTEXPR void on_plus() { specs_.sign = sign::plus; }
+  FMT_CONSTEXPR void on_minus() { specs_.sign = sign::minus; }
+  FMT_CONSTEXPR void on_space() { specs_.sign = sign::space; }
+  FMT_CONSTEXPR void on_hash() { specs_.alt = true; }
 
-  FMT_CONSTEXPR20 void remove_leading_zeros() {
-    int num_bigits = static_cast<int>(bigits_.size()) - 1;
-    while (num_bigits > 0 && (*this)[num_bigits] == 0) --num_bigits;
-    bigits_.resize(to_unsigned(num_bigits + 1));
+  FMT_CONSTEXPR void on_zero() {
+    specs_.align = align::numeric;
+    specs_.fill[0] = Char('0');
   }
 
-  // Computes *this -= other assuming aligned bigints and *this >= other.
-  FMT_CONSTEXPR20 void subtract_aligned(const bigint& other) {
-    FMT_ASSERT(other.exp_ >= exp_, "unaligned bigints");
-    FMT_ASSERT(compare(*this, other) >= 0, "");
-    bigit borrow = 0;
-    int i = other.exp_ - exp_;
-    for (size_t j = 0, n = other.bigits_.size(); j != n; ++i, ++j)
-      subtract_bigits(i, other.bigits_[j], borrow);
-    while (borrow > 0) subtract_bigits(i, 0, borrow);
-    remove_leading_zeros();
+  FMT_CONSTEXPR void on_width(int width) { specs_.width = width; }
+  FMT_CONSTEXPR void on_precision(int precision) {
+    specs_.precision = precision;
   }
+  FMT_CONSTEXPR void end_precision() {}
 
-  FMT_CONSTEXPR20 void multiply(uint32_t value) {
-    const double_bigit wide_value = value;
-    bigit carry = 0;
-    for (size_t i = 0, n = bigits_.size(); i < n; ++i) {
-      double_bigit result = bigits_[i] * wide_value + carry;
-      bigits_[i] = static_cast<bigit>(result);
-      carry = static_cast<bigit>(result >> bigit_bits);
-    }
-    if (carry != 0) bigits_.push_back(carry);
-  }
-
-  template <typename UInt, FMT_ENABLE_IF(std::is_same<UInt, uint64_t>::value ||
-                                         std::is_same<UInt, uint128_t>::value)>
-  FMT_CONSTEXPR20 void multiply(UInt value) {
-    using half_uint =
-        conditional_t<std::is_same<UInt, uint128_t>::value, uint64_t, uint32_t>;
-    const int shift = num_bits<half_uint>() - bigit_bits;
-    const UInt lower = static_cast<half_uint>(value);
-    const UInt upper = value >> num_bits<half_uint>();
-    UInt carry = 0;
-    for (size_t i = 0, n = bigits_.size(); i < n; ++i) {
-      UInt result = lower * bigits_[i] + static_cast<bigit>(carry);
-      carry = (upper * bigits_[i] << shift) + (result >> bigit_bits) +
-              (carry >> bigit_bits);
-      bigits_[i] = static_cast<bigit>(result);
-    }
-    while (carry != 0) {
-      bigits_.push_back(static_cast<bigit>(carry));
-      carry >>= bigit_bits;
+  FMT_CONSTEXPR void on_type(Char type) {
+    specs_.type = static_cast<char>(type);
+  }
+
+ protected:
+  basic_format_specs<Char>& specs_;
+};
+
+template <typename ErrorHandler> class numeric_specs_checker {
+ public:
+  FMT_CONSTEXPR numeric_specs_checker(ErrorHandler& eh, detail::type arg_type)
+      : error_handler_(eh), arg_type_(arg_type) {}
+
+  FMT_CONSTEXPR void require_numeric_argument() {
+    if (!is_arithmetic_type(arg_type_))
+      error_handler_.on_error("format specifier requires numeric argument");
+  }
+
+  FMT_CONSTEXPR void check_sign() {
+    require_numeric_argument();
+    if (is_integral_type(arg_type_) && arg_type_ != type::int_type &&
+        arg_type_ != type::long_long_type && arg_type_ != type::char_type) {
+      error_handler_.on_error("format specifier requires signed argument");
     }
   }
 
-  template <typename UInt, FMT_ENABLE_IF(std::is_same<UInt, uint64_t>::value ||
-                                         std::is_same<UInt, uint128_t>::value)>
-  FMT_CONSTEXPR20 void assign(UInt n) {
-    size_t num_bigits = 0;
-    do {
-      bigits_[num_bigits++] = static_cast<bigit>(n);
-      n >>= bigit_bits;
-    } while (n != 0);
-    bigits_.resize(num_bigits);
-    exp_ = 0;
+  FMT_CONSTEXPR void check_precision() {
+    if (is_integral_type(arg_type_) || arg_type_ == type::pointer_type)
+      error_handler_.on_error("precision not allowed for this argument type");
   }
 
+ private:
+  ErrorHandler& error_handler_;
+  detail::type arg_type_;
+};
+
+// A format specifier handler that checks if specifiers are consistent with the
+// argument type.
+template <typename Handler> class specs_checker : public Handler {
+ private:
+  numeric_specs_checker<Handler> checker_;
+
+  // Suppress an MSVC warning about using this in initializer list.
+  FMT_CONSTEXPR Handler& error_handler() { return *this; }
+
  public:
-  FMT_CONSTEXPR20 bigint() : exp_(0) {}
-  explicit bigint(uint64_t n) { assign(n); }
+  FMT_CONSTEXPR specs_checker(const Handler& handler, detail::type arg_type)
+      : Handler(handler), checker_(error_handler(), arg_type) {}
 
-  bigint(const bigint&) = delete;
-  void operator=(const bigint&) = delete;
+  FMT_CONSTEXPR specs_checker(const specs_checker& other)
+      : Handler(other), checker_(error_handler(), other.arg_type_) {}
 
-  FMT_CONSTEXPR20 void assign(const bigint& other) {
-    auto size = other.bigits_.size();
-    bigits_.resize(size);
-    auto data = other.bigits_.data();
-    copy_str<bigit>(data, data + size, bigits_.data());
-    exp_ = other.exp_;
+  FMT_CONSTEXPR void on_align(align_t align) {
+    if (align == align::numeric) checker_.require_numeric_argument();
+    Handler::on_align(align);
   }
 
-  template <typename Int> FMT_CONSTEXPR20 void operator=(Int n) {
-    FMT_ASSERT(n > 0, "");
-    assign(uint64_or_128_t<Int>(n));
+  FMT_CONSTEXPR void on_plus() {
+    checker_.check_sign();
+    Handler::on_plus();
   }
 
-  FMT_CONSTEXPR20 int num_bigits() const {
-    return static_cast<int>(bigits_.size()) + exp_;
+  FMT_CONSTEXPR void on_minus() {
+    checker_.check_sign();
+    Handler::on_minus();
   }
 
-  FMT_NOINLINE FMT_CONSTEXPR20 bigint& operator<<=(int shift) {
-    FMT_ASSERT(shift >= 0, "");
-    exp_ += shift / bigit_bits;
-    shift %= bigit_bits;
-    if (shift == 0) return *this;
-    bigit carry = 0;
-    for (size_t i = 0, n = bigits_.size(); i < n; ++i) {
-      bigit c = bigits_[i] >> (bigit_bits - shift);
-      bigits_[i] = (bigits_[i] << shift) + carry;
-      carry = c;
-    }
-    if (carry != 0) bigits_.push_back(carry);
-    return *this;
+  FMT_CONSTEXPR void on_space() {
+    checker_.check_sign();
+    Handler::on_space();
   }
 
-  template <typename Int> FMT_CONSTEXPR20 bigint& operator*=(Int value) {
-    FMT_ASSERT(value > 0, "");
-    multiply(uint32_or_64_or_128_t<Int>(value));
-    return *this;
+  FMT_CONSTEXPR void on_hash() {
+    checker_.require_numeric_argument();
+    Handler::on_hash();
+  }
+
+  FMT_CONSTEXPR void on_zero() {
+    checker_.require_numeric_argument();
+    Handler::on_zero();
+  }
+
+  FMT_CONSTEXPR void end_precision() { checker_.check_precision(); }
+};
+
+template <template <typename> class Handler, typename FormatArg,
+          typename ErrorHandler>
+FMT_CONSTEXPR int get_dynamic_spec(FormatArg arg, ErrorHandler eh) {
+  unsigned long long value = visit_format_arg(Handler<ErrorHandler>(eh), arg);
+  if (value > to_unsigned(max_value<int>())) eh.on_error("number is too big");
+  return static_cast<int>(value);
+}
+
+struct auto_id {};
+
+template <typename Context, typename ID>
+FMT_CONSTEXPR typename Context::format_arg get_arg(Context& ctx, ID id) {
+  auto arg = ctx.arg(id);
+  if (!arg) ctx.on_error("argument not found");
+  return arg;
+}
+
+// The standard format specifier handler with checking.
+template <typename ParseContext, typename Context>
+class specs_handler : public specs_setter<typename Context::char_type> {
+ public:
+  using char_type = typename Context::char_type;
+
+  FMT_CONSTEXPR specs_handler(basic_format_specs<char_type>& specs,
+                              ParseContext& parse_ctx, Context& ctx)
+      : specs_setter<char_type>(specs),
+        parse_context_(parse_ctx),
+        context_(ctx) {}
+
+  template <typename Id> FMT_CONSTEXPR void on_dynamic_width(Id arg_id) {
+    this->specs_.width = get_dynamic_spec<width_checker>(
+        get_arg(arg_id), context_.error_handler());
+  }
+
+  template <typename Id> FMT_CONSTEXPR void on_dynamic_precision(Id arg_id) {
+    this->specs_.precision = get_dynamic_spec<precision_checker>(
+        get_arg(arg_id), context_.error_handler());
+  }
+
+  void on_error(const char* message) { context_.on_error(message); }
+
+ private:
+  // This is only needed for compatibility with gcc 4.4.
+  using format_arg = typename Context::format_arg;
+
+  FMT_CONSTEXPR format_arg get_arg(auto_id) {
+    return detail::get_arg(context_, parse_context_.next_arg_id());
   }
 
-  friend FMT_CONSTEXPR20 int compare(const bigint& lhs, const bigint& rhs) {
-    int num_lhs_bigits = lhs.num_bigits(), num_rhs_bigits = rhs.num_bigits();
-    if (num_lhs_bigits != num_rhs_bigits)
-      return num_lhs_bigits > num_rhs_bigits ? 1 : -1;
-    int i = static_cast<int>(lhs.bigits_.size()) - 1;
-    int j = static_cast<int>(rhs.bigits_.size()) - 1;
-    int end = i - j;
-    if (end < 0) end = 0;
-    for (; i >= end; --i, --j) {
-      bigit lhs_bigit = lhs[i], rhs_bigit = rhs[j];
-      if (lhs_bigit != rhs_bigit) return lhs_bigit > rhs_bigit ? 1 : -1;
-    }
-    if (i != j) return i > j ? 1 : -1;
-    return 0;
+  FMT_CONSTEXPR format_arg get_arg(int arg_id) {
+    parse_context_.check_arg_id(arg_id);
+    return detail::get_arg(context_, arg_id);
   }
 
-  // Returns compare(lhs1 + lhs2, rhs).
-  friend FMT_CONSTEXPR20 int add_compare(const bigint& lhs1, const bigint& lhs2,
-                                         const bigint& rhs) {
-    auto minimum = [](int a, int b) { return a < b ? a : b; };
-    auto maximum = [](int a, int b) { return a > b ? a : b; };
-    int max_lhs_bigits = maximum(lhs1.num_bigits(), lhs2.num_bigits());
-    int num_rhs_bigits = rhs.num_bigits();
-    if (max_lhs_bigits + 1 < num_rhs_bigits) return -1;
-    if (max_lhs_bigits > num_rhs_bigits) return 1;
-    auto get_bigit = [](const bigint& n, int i) -> bigit {
-      return i >= n.exp_ && i < n.num_bigits() ? n[i - n.exp_] : 0;
-    };
-    double_bigit borrow = 0;
-    int min_exp = minimum(minimum(lhs1.exp_, lhs2.exp_), rhs.exp_);
-    for (int i = num_rhs_bigits - 1; i >= min_exp; --i) {
-      double_bigit sum =
-          static_cast<double_bigit>(get_bigit(lhs1, i)) + get_bigit(lhs2, i);
-      bigit rhs_bigit = get_bigit(rhs, i);
-      if (sum > rhs_bigit + borrow) return 1;
-      borrow = rhs_bigit + borrow - sum;
-      if (borrow > 1) return -1;
-      borrow <<= bigit_bits;
-    }
-    return borrow != 0 ? -1 : 0;
-  }
-
-  // Assigns pow(10, exp) to this bigint.
-  FMT_CONSTEXPR20 void assign_pow10(int exp) {
-    FMT_ASSERT(exp >= 0, "");
-    if (exp == 0) return *this = 1;
-    // Find the top bit.
-    int bitmask = 1;
-    while (exp >= bitmask) bitmask <<= 1;
-    bitmask >>= 1;
-    // pow(10, exp) = pow(5, exp) * pow(2, exp). First compute pow(5, exp) by
-    // repeated squaring and multiplication.
-    *this = 5;
-    bitmask >>= 1;
-    while (bitmask != 0) {
-      square();
-      if ((exp & bitmask) != 0) *this *= 5;
-      bitmask >>= 1;
-    }
-    *this <<= exp;  // Multiply by pow(2, exp) by shifting.
-  }
-
-  FMT_CONSTEXPR20 void square() {
-    int num_bigits = static_cast<int>(bigits_.size());
-    int num_result_bigits = 2 * num_bigits;
-    basic_memory_buffer<bigit, bigits_capacity> n(std::move(bigits_));
-    bigits_.resize(to_unsigned(num_result_bigits));
-    auto sum = uint128_t();
-    for (int bigit_index = 0; bigit_index < num_bigits; ++bigit_index) {
-      // Compute bigit at position bigit_index of the result by adding
-      // cross-product terms n[i] * n[j] such that i + j == bigit_index.
-      for (int i = 0, j = bigit_index; j >= 0; ++i, --j) {
-        // Most terms are multiplied twice which can be optimized in the future.
-        sum += static_cast<double_bigit>(n[i]) * n[j];
-      }
-      (*this)[bigit_index] = static_cast<bigit>(sum);
-      sum >>= num_bits<bigit>();  // Compute the carry.
-    }
-    // Do the same for the top half.
-    for (int bigit_index = num_bigits; bigit_index < num_result_bigits;
-         ++bigit_index) {
-      for (int j = num_bigits - 1, i = bigit_index - j; i < num_bigits;)
-        sum += static_cast<double_bigit>(n[i++]) * n[j--];
-      (*this)[bigit_index] = static_cast<bigit>(sum);
-      sum >>= num_bits<bigit>();
-    }
-    remove_leading_zeros();
-    exp_ *= 2;
-  }
-
-  // If this bigint has a bigger exponent than other, adds trailing zero to make
-  // exponents equal. This simplifies some operations such as subtraction.
-  FMT_CONSTEXPR20 void align(const bigint& other) {
-    int exp_difference = exp_ - other.exp_;
-    if (exp_difference <= 0) return;
-    int num_bigits = static_cast<int>(bigits_.size());
-    bigits_.resize(to_unsigned(num_bigits + exp_difference));
-    for (int i = num_bigits - 1, j = i + exp_difference; i >= 0; --i, --j)
-      bigits_[j] = bigits_[i];
-    std::uninitialized_fill_n(bigits_.data(), exp_difference, 0u);
-    exp_ -= exp_difference;
-  }
-
-  // Divides this bignum by divisor, assigning the remainder to this and
-  // returning the quotient.
-  FMT_CONSTEXPR20 int divmod_assign(const bigint& divisor) {
-    FMT_ASSERT(this != &divisor, "");
-    if (compare(*this, divisor) < 0) return 0;
-    FMT_ASSERT(divisor.bigits_[divisor.bigits_.size() - 1u] != 0, "");
-    align(divisor);
-    int quotient = 0;
-    do {
-      subtract_aligned(divisor);
-      ++quotient;
-    } while (compare(*this, divisor) >= 0);
-    return quotient;
+  FMT_CONSTEXPR format_arg get_arg(basic_string_view<char_type> arg_id) {
+    parse_context_.check_arg_id(arg_id);
+    return detail::get_arg(context_, arg_id);
   }
-};
 
-// format_dragon flags.
-enum dragon {
-  predecessor_closer = 1,
-  fixup = 2,  // Run fixup to correct exp10 which can be off by one.
-  fixed = 4,
+  ParseContext& parse_context_;
+  Context& context_;
 };
 
-// Formats a floating-point number using a variation of the Fixed-Precision
-// Positive Floating-Point Printout ((FPP)^2) algorithm by Steele & White:
-// https://fmt.dev/papers/p372-steele.pdf.
-FMT_CONSTEXPR20 inline void format_dragon(basic_fp<uint128_t> value,
-                                          unsigned flags, int num_digits,
-                                          buffer<char>& buf, int& exp10) {
-  bigint numerator;    // 2 * R in (FPP)^2.
-  bigint denominator;  // 2 * S in (FPP)^2.
-  // lower and upper are differences between value and corresponding boundaries.
-  bigint lower;             // (M^- in (FPP)^2).
-  bigint upper_store;       // upper's value if different from lower.
-  bigint* upper = nullptr;  // (M^+ in (FPP)^2).
-  // Shift numerator and denominator by an extra bit or two (if lower boundary
-  // is closer) to make lower and upper integers. This eliminates multiplication
-  // by 2 during later computations.
-  bool is_predecessor_closer = (flags & dragon::predecessor_closer) != 0;
-  int shift = is_predecessor_closer ? 2 : 1;
-  if (value.e >= 0) {
-    numerator = value.f;
-    numerator <<= value.e + shift;
-    lower = 1;
-    lower <<= value.e;
-    if (is_predecessor_closer) {
-      upper_store = 1;
-      upper_store <<= value.e + 1;
-      upper = &upper_store;
-    }
-    denominator.assign_pow10(exp10);
-    denominator <<= shift;
-  } else if (exp10 < 0) {
-    numerator.assign_pow10(-exp10);
-    lower.assign(numerator);
-    if (is_predecessor_closer) {
-      upper_store.assign(numerator);
-      upper_store <<= 1;
-      upper = &upper_store;
-    }
-    numerator *= value.f;
-    numerator <<= shift;
-    denominator = 1;
-    denominator <<= shift - value.e;
-  } else {
-    numerator = value.f;
-    numerator <<= shift;
-    denominator.assign_pow10(exp10);
-    denominator <<= shift - value.e;
-    lower = 1;
-    if (is_predecessor_closer) {
-      upper_store = 1ULL << 1;
-      upper = &upper_store;
-    }
-  }
-  int even = static_cast<int>((value.f & 1) == 0);
-  if (!upper) upper = &lower;
-  bool shortest = num_digits < 0;
-  if ((flags & dragon::fixup) != 0) {
-    if (add_compare(numerator, *upper, denominator) + even <= 0) {
-      --exp10;
-      numerator *= 10;
-      if (num_digits < 0) {
-        lower *= 10;
-        if (upper != &lower) *upper *= 10;
-      }
-    }
-    if ((flags & dragon::fixed) != 0) adjust_precision(num_digits, exp10 + 1);
-  }
-  // Invariant: value == (numerator / denominator) * pow(10, exp10).
-  if (shortest) {
-    // Generate the shortest representation.
-    num_digits = 0;
-    char* data = buf.data();
-    for (;;) {
-      int digit = numerator.divmod_assign(denominator);
-      bool low = compare(numerator, lower) - even < 0;  // numerator <[=] lower.
-      // numerator + upper >[=] pow10:
-      bool high = add_compare(numerator, *upper, denominator) + even > 0;
-      data[num_digits++] = static_cast<char>('0' + digit);
-      if (low || high) {
-        if (!low) {
-          ++data[num_digits - 1];
-        } else if (high) {
-          int result = add_compare(numerator, numerator, denominator);
-          // Round half to even.
-          if (result > 0 || (result == 0 && (digit % 2) != 0))
-            ++data[num_digits - 1];
-        }
-        buf.try_resize(to_unsigned(num_digits));
-        exp10 -= num_digits - 1;
-        return;
-      }
-      numerator *= 10;
-      lower *= 10;
-      if (upper != &lower) *upper *= 10;
-    }
-  }
-  // Generate the given number of digits.
-  exp10 -= num_digits - 1;
-  if (num_digits <= 0) {
-    denominator *= 10;
-    auto digit = add_compare(numerator, numerator, denominator) > 0 ? '1' : '0';
-    buf.push_back(digit);
-    return;
-  }
-  buf.try_resize(to_unsigned(num_digits));
-  for (int i = 0; i < num_digits - 1; ++i) {
-    int digit = numerator.divmod_assign(denominator);
-    buf[i] = static_cast<char>('0' + digit);
-    numerator *= 10;
-  }
-  int digit = numerator.divmod_assign(denominator);
-  auto result = add_compare(numerator, numerator, denominator);
-  if (result > 0 || (result == 0 && (digit % 2) != 0)) {
-    if (digit == 9) {
-      const auto overflow = '0' + 10;
-      buf[num_digits - 1] = overflow;
-      // Propagate the carry.
-      for (int i = num_digits - 1; i > 0 && buf[i] == overflow; --i) {
-        buf[i] = '0';
-        ++buf[i - 1];
-      }
-      if (buf[0] == overflow) {
-        buf[0] = '1';
-        if ((flags & dragon::fixed) != 0)
-          buf.push_back('0');
-        else
-          ++exp10;
-      }
-      return;
-    }
-    ++digit;
-  }
-  buf[num_digits - 1] = static_cast<char>('0' + digit);
-}
+enum class arg_id_kind { none, index, name };
 
-// Formats a floating-point number using the hexfloat format.
-template <typename Float, FMT_ENABLE_IF(!is_double_double<Float>::value)>
-FMT_CONSTEXPR20 void format_hexfloat(Float value, int precision,
-                                     float_specs specs, buffer<char>& buf) {
-  // float is passed as double to reduce the number of instantiations and to
-  // simplify implementation.
-  static_assert(!std::is_same<Float, float>::value, "");
+// An argument reference.
+template <typename Char> struct arg_ref {
+  FMT_CONSTEXPR arg_ref() : kind(arg_id_kind::none), val() {}
 
-  using info = dragonbox::float_info<Float>;
+  FMT_CONSTEXPR explicit arg_ref(int index)
+      : kind(arg_id_kind::index), val(index) {}
+  FMT_CONSTEXPR explicit arg_ref(basic_string_view<Char> name)
+      : kind(arg_id_kind::name), val(name) {}
 
-  // Assume Float is in the format [sign][exponent][significand].
-  using carrier_uint = typename info::carrier_uint;
+  FMT_CONSTEXPR arg_ref& operator=(int idx) {
+    kind = arg_id_kind::index;
+    val.index = idx;
+    return *this;
+  }
 
-  constexpr auto num_float_significand_bits =
-      detail::num_significand_bits<Float>();
+  arg_id_kind kind;
+  union value {
+    FMT_CONSTEXPR value(int id = 0) : index{id} {}
+    FMT_CONSTEXPR value(basic_string_view<Char> n) : name(n) {}
 
-  basic_fp<carrier_uint> f(value);
-  f.e += num_float_significand_bits;
-  if (!has_implicit_bit<Float>()) --f.e;
+    int index;
+    basic_string_view<Char> name;
+  } val;
+};
 
-  constexpr auto num_fraction_bits =
-      num_float_significand_bits + (has_implicit_bit<Float>() ? 1 : 0);
-  constexpr auto num_xdigits = (num_fraction_bits + 3) / 4;
+// Format specifiers with width and precision resolved at formatting rather
+// than parsing time to allow re-using the same parsed specifiers with
+// different sets of arguments (precompilation of format strings).
+template <typename Char>
+struct dynamic_format_specs : basic_format_specs<Char> {
+  arg_ref<Char> width_ref;
+  arg_ref<Char> precision_ref;
+};
 
-  constexpr auto leading_shift = ((num_xdigits - 1) * 4);
-  const auto leading_mask = carrier_uint(0xF) << leading_shift;
-  const auto leading_xdigit =
-      static_cast<uint32_t>((f.f & leading_mask) >> leading_shift);
-  if (leading_xdigit > 1) f.e -= (32 - countl_zero(leading_xdigit) - 1);
+// Format spec handler that saves references to arguments representing dynamic
+// width and precision to be resolved at formatting time.
+template <typename ParseContext>
+class dynamic_specs_handler
+    : public specs_setter<typename ParseContext::char_type> {
+ public:
+  using char_type = typename ParseContext::char_type;
 
-  int print_xdigits = num_xdigits - 1;
-  if (precision >= 0 && print_xdigits > precision) {
-    const int shift = ((print_xdigits - precision - 1) * 4);
-    const auto mask = carrier_uint(0xF) << shift;
-    const auto v = static_cast<uint32_t>((f.f & mask) >> shift);
+  FMT_CONSTEXPR dynamic_specs_handler(dynamic_format_specs<char_type>& specs,
+                                      ParseContext& ctx)
+      : specs_setter<char_type>(specs), specs_(specs), context_(ctx) {}
 
-    if (v >= 8) {
-      const auto inc = carrier_uint(1) << (shift + 4);
-      f.f += inc;
-      f.f &= ~(inc - 1);
-    }
+  FMT_CONSTEXPR dynamic_specs_handler(const dynamic_specs_handler& other)
+      : specs_setter<char_type>(other),
+        specs_(other.specs_),
+        context_(other.context_) {}
 
-    // Check long double overflow
-    if (!has_implicit_bit<Float>()) {
-      const auto implicit_bit = carrier_uint(1) << num_float_significand_bits;
-      if ((f.f & implicit_bit) == implicit_bit) {
-        f.f >>= 4;
-        f.e += 4;
-      }
-    }
+  template <typename Id> FMT_CONSTEXPR void on_dynamic_width(Id arg_id) {
+    specs_.width_ref = make_arg_ref(arg_id);
+  }
 
-    print_xdigits = precision;
+  template <typename Id> FMT_CONSTEXPR void on_dynamic_precision(Id arg_id) {
+    specs_.precision_ref = make_arg_ref(arg_id);
   }
 
-  char xdigits[num_bits<carrier_uint>() / 4];
-  detail::fill_n(xdigits, sizeof(xdigits), '0');
-  format_uint<4>(xdigits, f.f, num_xdigits, specs.upper);
+  FMT_CONSTEXPR void on_error(const char* message) {
+    context_.on_error(message);
+  }
 
-  // Remove zero tail
-  while (print_xdigits > 0 && xdigits[print_xdigits] == '0') --print_xdigits;
+ private:
+  using arg_ref_type = arg_ref<char_type>;
 
-  buf.push_back('0');
-  buf.push_back(specs.upper ? 'X' : 'x');
-  buf.push_back(xdigits[0]);
-  if (specs.showpoint || print_xdigits > 0 || print_xdigits < precision)
-    buf.push_back('.');
-  buf.append(xdigits + 1, xdigits + 1 + print_xdigits);
-  for (; print_xdigits < precision; ++print_xdigits) buf.push_back('0');
+  FMT_CONSTEXPR arg_ref_type make_arg_ref(int arg_id) {
+    context_.check_arg_id(arg_id);
+    return arg_ref_type(arg_id);
+  }
 
-  buf.push_back(specs.upper ? 'P' : 'p');
+  FMT_CONSTEXPR arg_ref_type make_arg_ref(auto_id) {
+    return arg_ref_type(context_.next_arg_id());
+  }
 
-  uint32_t abs_e;
-  if (f.e < 0) {
-    buf.push_back('-');
-    abs_e = static_cast<uint32_t>(-f.e);
-  } else {
-    buf.push_back('+');
-    abs_e = static_cast<uint32_t>(f.e);
-  }
-  format_decimal<char>(appender(buf), abs_e, detail::count_digits(abs_e));
-}
-
-template <typename Float, FMT_ENABLE_IF(is_double_double<Float>::value)>
-FMT_CONSTEXPR20 void format_hexfloat(Float value, int precision,
-                                     float_specs specs, buffer<char>& buf) {
-  format_hexfloat(static_cast<double>(value), precision, specs, buf);
-}
-
-constexpr uint32_t fractional_part_rounding_thresholds(int index) {
-  // For checking rounding thresholds.
-  // The kth entry is chosen to be the smallest integer such that the
-  // upper 32-bits of 10^(k+1) times it is strictly bigger than 5 * 10^k.
-  // It is equal to ceil(2^31 + 2^32/10^(k + 1)).
-  // These are stored in a string literal because we cannot have static arrays
-  // in constexpr functions and non-static ones are poorly optimized.
-  return U"\x9999999a\x828f5c29\x80418938\x80068db9\x8000a7c6\x800010c7"
-         U"\x800001ae\x8000002b"[index];
-}
-
-template <typename Float>
-FMT_CONSTEXPR20 auto format_float(Float value, int precision, float_specs specs,
-                                  buffer<char>& buf) -> int {
-  // float is passed as double to reduce the number of instantiations.
-  static_assert(!std::is_same<Float, float>::value, "");
-  FMT_ASSERT(value >= 0, "value is negative");
-  auto converted_value = convert_float(value);
-
-  const bool fixed = specs.format == float_format::fixed;
-  if (value <= 0) {  // <= instead of == to silence a warning.
-    if (precision <= 0 || !fixed) {
-      buf.push_back('0');
-      return 0;
-    }
-    buf.try_resize(to_unsigned(precision));
-    fill_n(buf.data(), precision, '0');
-    return -precision;
-  }
-
-  int exp = 0;
-  bool use_dragon = true;
-  unsigned dragon_flags = 0;
-  if (!is_fast_float<Float>() || is_constant_evaluated()) {
-    const auto inv_log2_10 = 0.3010299956639812;  // 1 / log2(10)
-    using info = dragonbox::float_info<decltype(converted_value)>;
-    const auto f = basic_fp<typename info::carrier_uint>(converted_value);
-    // Compute exp, an approximate power of 10, such that
-    //   10^(exp - 1) <= value < 10^exp or 10^exp <= value < 10^(exp + 1).
-    // This is based on log10(value) == log2(value) / log2(10) and approximation
-    // of log2(value) by e + num_fraction_bits idea from double-conversion.
-    auto e = (f.e + count_digits<1>(f.f) - 1) * inv_log2_10 - 1e-10;
-    exp = static_cast<int>(e);
-    if (e > exp) ++exp;  // Compute ceil.
-    dragon_flags = dragon::fixup;
-  } else if (precision < 0) {
-    // Use Dragonbox for the shortest format.
-    if (specs.binary32) {
-      auto dec = dragonbox::to_decimal(static_cast<float>(value));
-      write<char>(buffer_appender<char>(buf), dec.significand);
-      return dec.exponent;
-    }
-    auto dec = dragonbox::to_decimal(static_cast<double>(value));
-    write<char>(buffer_appender<char>(buf), dec.significand);
-    return dec.exponent;
-  } else {
-    // Extract significand bits and exponent bits.
-    using info = dragonbox::float_info<double>;
-    auto br = bit_cast<uint64_t>(static_cast<double>(value));
-
-    const uint64_t significand_mask =
-        (static_cast<uint64_t>(1) << num_significand_bits<double>()) - 1;
-    uint64_t significand = (br & significand_mask);
-    int exponent = static_cast<int>((br & exponent_mask<double>()) >>
-                                    num_significand_bits<double>());
-
-    if (exponent != 0) {  // Check if normal.
-      exponent -= exponent_bias<double>() + num_significand_bits<double>();
-      significand |=
-          (static_cast<uint64_t>(1) << num_significand_bits<double>());
-      significand <<= 1;
-    } else {
-      // Normalize subnormal inputs.
-      FMT_ASSERT(significand != 0, "zeros should not appear here");
-      int shift = countl_zero(significand);
-      FMT_ASSERT(shift >= num_bits<uint64_t>() - num_significand_bits<double>(),
-                 "");
-      shift -= (num_bits<uint64_t>() - num_significand_bits<double>() - 2);
-      exponent = (std::numeric_limits<double>::min_exponent -
-                  num_significand_bits<double>()) -
-                 shift;
-      significand <<= shift;
-    }
+  FMT_CONSTEXPR arg_ref_type make_arg_ref(basic_string_view<char_type> arg_id) {
+    context_.check_arg_id(arg_id);
+    basic_string_view<char_type> format_str(
+        context_.begin(), to_unsigned(context_.end() - context_.begin()));
+    return arg_ref_type(arg_id);
+  }
 
-    // Compute the first several nonzero decimal significand digits.
-    // We call the number we get the first segment.
-    const int k = info::kappa - dragonbox::floor_log10_pow2(exponent);
-    exp = -k;
-    const int beta = exponent + dragonbox::floor_log2_pow10(k);
-    uint64_t first_segment;
-    bool has_more_segments;
-    int digits_in_the_first_segment;
-    {
-      const auto r = dragonbox::umul192_upper128(
-          significand << beta, dragonbox::get_cached_power(k));
-      first_segment = r.high();
-      has_more_segments = r.low() != 0;
-
-      // The first segment can have 18 ~ 19 digits.
-      if (first_segment >= 1000000000000000000ULL) {
-        digits_in_the_first_segment = 19;
-      } else {
-        // When it is of 18-digits, we align it to 19-digits by adding a bogus
-        // zero at the end.
-        digits_in_the_first_segment = 18;
-        first_segment *= 10;
-      }
-    }
+  dynamic_format_specs<char_type>& specs_;
+  ParseContext& context_;
+};
 
-    // Compute the actual number of decimal digits to print.
-    if (fixed) adjust_precision(precision, exp + digits_in_the_first_segment);
-
-    // Use Dragon4 only when there might be not enough digits in the first
-    // segment.
-    if (digits_in_the_first_segment > precision) {
-      use_dragon = false;
-
-      if (precision <= 0) {
-        exp += digits_in_the_first_segment;
-
-        if (precision < 0) {
-          // Nothing to do, since all we have are just leading zeros.
-          buf.try_resize(0);
-        } else {
-          // We may need to round-up.
-          buf.try_resize(1);
-          if ((first_segment | static_cast<uint64_t>(has_more_segments)) >
-              5000000000000000000ULL) {
-            buf[0] = '1';
-          } else {
-            buf[0] = '0';
-          }
-        }
-      }  // precision <= 0
-      else {
-        exp += digits_in_the_first_segment - precision;
-
-        // When precision > 0, we divide the first segment into three
-        // subsegments, each with 9, 9, and 0 ~ 1 digits so that each fits
-        // in 32-bits which usually allows faster calculation than in
-        // 64-bits. Since some compiler (e.g. MSVC) doesn't know how to optimize
-        // division-by-constant for large 64-bit divisors, we do it here
-        // manually. The magic number 7922816251426433760 below is equal to
-        // ceil(2^(64+32) / 10^10).
-        const uint32_t first_subsegment = static_cast<uint32_t>(
-            dragonbox::umul128_upper64(first_segment, 7922816251426433760ULL) >>
-            32);
-        const uint64_t second_third_subsegments =
-            first_segment - first_subsegment * 10000000000ULL;
-
-        uint64_t prod;
-        uint32_t digits;
-        bool should_round_up;
-        int number_of_digits_to_print = precision > 9 ? 9 : precision;
-
-        // Print a 9-digits subsegment, either the first or the second.
-        auto print_subsegment = [&](uint32_t subsegment, char* buffer) {
-          int number_of_digits_printed = 0;
-
-          // If we want to print an odd number of digits from the subsegment,
-          if ((number_of_digits_to_print & 1) != 0) {
-            // Convert to 64-bit fixed-point fractional form with 1-digit
-            // integer part. The magic number 720575941 is a good enough
-            // approximation of 2^(32 + 24) / 10^8; see
-            // https://jk-jeon.github.io/posts/2022/12/fixed-precision-formatting/#fixed-length-case
-            // for details.
-            prod = ((subsegment * static_cast<uint64_t>(720575941)) >> 24) + 1;
-            digits = static_cast<uint32_t>(prod >> 32);
-            *buffer = static_cast<char>('0' + digits);
-            number_of_digits_printed++;
-          }
-          // If we want to print an even number of digits from the
-          // first_subsegment,
-          else {
-            // Convert to 64-bit fixed-point fractional form with 2-digits
-            // integer part. The magic number 450359963 is a good enough
-            // approximation of 2^(32 + 20) / 10^7; see
-            // https://jk-jeon.github.io/posts/2022/12/fixed-precision-formatting/#fixed-length-case
-            // for details.
-            prod = ((subsegment * static_cast<uint64_t>(450359963)) >> 20) + 1;
-            digits = static_cast<uint32_t>(prod >> 32);
-            copy2(buffer, digits2(digits));
-            number_of_digits_printed += 2;
-          }
-
-          // Print all digit pairs.
-          while (number_of_digits_printed < number_of_digits_to_print) {
-            prod = static_cast<uint32_t>(prod) * static_cast<uint64_t>(100);
-            digits = static_cast<uint32_t>(prod >> 32);
-            copy2(buffer + number_of_digits_printed, digits2(digits));
-            number_of_digits_printed += 2;
-          }
-        };
-
-        // Print first subsegment.
-        print_subsegment(first_subsegment, buf.data());
-
-        // Perform rounding if the first subsegment is the last subsegment to
-        // print.
-        if (precision <= 9) {
-          // Rounding inside the subsegment.
-          // We round-up if:
-          //  - either the fractional part is strictly larger than 1/2, or
-          //  - the fractional part is exactly 1/2 and the last digit is odd.
-          // We rely on the following observations:
-          //  - If fractional_part >= threshold, then the fractional part is
-          //    strictly larger than 1/2.
-          //  - If the MSB of fractional_part is set, then the fractional part
-          //    must be at least 1/2.
-          //  - When the MSB of fractional_part is set, either
-          //    second_third_subsegments being nonzero or has_more_segments
-          //    being true means there are further digits not printed, so the
-          //    fractional part is strictly larger than 1/2.
-          if (precision < 9) {
-            uint32_t fractional_part = static_cast<uint32_t>(prod);
-            should_round_up =
-                fractional_part >= fractional_part_rounding_thresholds(
-                                       8 - number_of_digits_to_print) ||
-                ((fractional_part >> 31) &
-                 ((digits & 1) | (second_third_subsegments != 0) |
-                  has_more_segments)) != 0;
-          }
-          // Rounding at the subsegment boundary.
-          // In this case, the fractional part is at least 1/2 if and only if
-          // second_third_subsegments >= 5000000000ULL, and is strictly larger
-          // than 1/2 if we further have either second_third_subsegments >
-          // 5000000000ULL or has_more_segments == true.
-          else {
-            should_round_up = second_third_subsegments > 5000000000ULL ||
-                              (second_third_subsegments == 5000000000ULL &&
-                               ((digits & 1) != 0 || has_more_segments));
-          }
-        }
-        // Otherwise, print the second subsegment.
-        else {
-          // Compilers are not aware of how to leverage the maximum value of
-          // second_third_subsegments to find out a better magic number which
-          // allows us to eliminate an additional shift. 1844674407370955162 =
-          // ceil(2^64/10) < ceil(2^64*(10^9/(10^10 - 1))).
-          const uint32_t second_subsegment =
-              static_cast<uint32_t>(dragonbox::umul128_upper64(
-                  second_third_subsegments, 1844674407370955162ULL));
-          const uint32_t third_subsegment =
-              static_cast<uint32_t>(second_third_subsegments) -
-              second_subsegment * 10;
-
-          number_of_digits_to_print = precision - 9;
-          print_subsegment(second_subsegment, buf.data() + 9);
-
-          // Rounding inside the subsegment.
-          if (precision < 18) {
-            // The condition third_subsegment != 0 implies that the segment was
-            // of 19 digits, so in this case the third segment should be
-            // consisting of a genuine digit from the input.
-            uint32_t fractional_part = static_cast<uint32_t>(prod);
-            should_round_up =
-                fractional_part >= fractional_part_rounding_thresholds(
-                                       8 - number_of_digits_to_print) ||
-                ((fractional_part >> 31) &
-                 ((digits & 1) | (third_subsegment != 0) |
-                  has_more_segments)) != 0;
-          }
-          // Rounding at the subsegment boundary.
-          else {
-            // In this case, the segment must be of 19 digits, thus
-            // the third subsegment should be consisting of a genuine digit from
-            // the input.
-            should_round_up = third_subsegment > 5 ||
-                              (third_subsegment == 5 &&
-                               ((digits & 1) != 0 || has_more_segments));
-          }
-        }
-
-        // Round-up if necessary.
-        if (should_round_up) {
-          ++buf[precision - 1];
-          for (int i = precision - 1; i > 0 && buf[i] > '9'; --i) {
-            buf[i] = '0';
-            ++buf[i - 1];
-          }
-          if (buf[0] > '9') {
-            buf[0] = '1';
-            if (fixed)
-              buf[precision++] = '0';
-            else
-              ++exp;
-          }
-        }
-        buf.try_resize(to_unsigned(precision));
-      }
-    }  // if (digits_in_the_first_segment > precision)
-    else {
-      // Adjust the exponent for its use in Dragon4.
-      exp += digits_in_the_first_segment - 1;
-    }
+template <typename Char, typename IDHandler>
+FMT_CONSTEXPR const Char* parse_arg_id(const Char* begin, const Char* end,
+                                       IDHandler&& handler) {
+  FMT_ASSERT(begin != end, "");
+  Char c = *begin;
+  if (c == '}' || c == ':') {
+    handler();
+    return begin;
   }
-  if (use_dragon) {
-    auto f = basic_fp<uint128_t>();
-    bool is_predecessor_closer = specs.binary32
-                                     ? f.assign(static_cast<float>(value))
-                                     : f.assign(converted_value);
-    if (is_predecessor_closer) dragon_flags |= dragon::predecessor_closer;
-    if (fixed) dragon_flags |= dragon::fixed;
-    // Limit precision to the maximum possible number of significant digits in
-    // an IEEE754 double because we don't need to generate zeros.
-    const int max_double_digits = 767;
-    if (precision > max_double_digits) precision = max_double_digits;
-    format_dragon(f, dragon_flags, precision, buf, exp);
-  }
-  if (!fixed && !specs.showpoint) {
-    // Remove trailing zeros.
-    auto num_digits = buf.size();
-    while (num_digits > 0 && buf[num_digits - 1] == '0') {
-      --num_digits;
-      ++exp;
-    }
-    buf.try_resize(num_digits);
+  if (c >= '0' && c <= '9') {
+    int index = 0;
+    if (c != '0')
+      index = parse_nonnegative_int(begin, end, handler);
+    else
+      ++begin;
+    if (begin == end || (*begin != '}' && *begin != ':'))
+      handler.on_error("invalid format string");
+    else
+      handler(index);
+    return begin;
   }
-  return exp;
-}
-template <typename Char, typename OutputIt, typename T>
-FMT_CONSTEXPR20 auto write_float(OutputIt out, T value,
-                                 format_specs<Char> specs, locale_ref loc)
-    -> OutputIt {
-  float_specs fspecs = parse_float_type_spec(specs);
-  fspecs.sign = specs.sign;
-  if (detail::signbit(value)) {  // value < 0 is false for NaN so use signbit.
-    fspecs.sign = sign::minus;
-    value = -value;
-  } else if (fspecs.sign == sign::minus) {
-    fspecs.sign = sign::none;
+  if (!is_name_start(c)) {
+    handler.on_error("invalid format string");
+    return begin;
   }
+  auto it = begin;
+  do {
+    ++it;
+  } while (it != end && (is_name_start(c = *it) || ('0' <= c && c <= '9')));
+  handler(basic_string_view<Char>(begin, to_unsigned(it - begin)));
+  return it;
+}
 
-  if (!detail::isfinite(value))
-    return write_nonfinite(out, detail::isnan(value), specs, fspecs);
+// Adapts SpecHandler to IDHandler API for dynamic width.
+template <typename SpecHandler, typename Char> struct width_adapter {
+  explicit FMT_CONSTEXPR width_adapter(SpecHandler& h) : handler(h) {}
 
-  if (specs.align == align::numeric && fspecs.sign) {
-    auto it = reserve(out, 1);
-    *it++ = detail::sign<Char>(fspecs.sign);
-    out = base_iterator(out, it);
-    fspecs.sign = sign::none;
-    if (specs.width != 0) --specs.width;
+  FMT_CONSTEXPR void operator()() { handler.on_dynamic_width(auto_id()); }
+  FMT_CONSTEXPR void operator()(int id) { handler.on_dynamic_width(id); }
+  FMT_CONSTEXPR void operator()(basic_string_view<Char> id) {
+    handler.on_dynamic_width(id);
   }
 
-  memory_buffer buffer;
-  if (fspecs.format == float_format::hex) {
-    if (fspecs.sign) buffer.push_back(detail::sign<char>(fspecs.sign));
-    format_hexfloat(convert_float(value), specs.precision, fspecs, buffer);
-    return write_bytes<align::right>(out, {buffer.data(), buffer.size()},
-                                     specs);
-  }
-  int precision = specs.precision >= 0 || specs.type == presentation_type::none
-                      ? specs.precision
-                      : 6;
-  if (fspecs.format == float_format::exp) {
-    if (precision == max_value<int>())
-      throw_format_error("number is too big");
-    else
-      ++precision;
-  } else if (fspecs.format != float_format::fixed && precision == 0) {
-    precision = 1;
+  FMT_CONSTEXPR void on_error(const char* message) {
+    handler.on_error(message);
   }
-  if (const_check(std::is_same<T, float>())) fspecs.binary32 = true;
-  int exp = format_float(convert_float(value), precision, fspecs, buffer);
-  fspecs.precision = precision;
-  auto f = big_decimal_fp{buffer.data(), static_cast<int>(buffer.size()), exp};
-  return write_float(out, f, specs, fspecs, loc);
-}
 
-template <typename Char, typename OutputIt, typename T,
-          FMT_ENABLE_IF(is_floating_point<T>::value)>
-FMT_CONSTEXPR20 auto write(OutputIt out, T value, format_specs<Char> specs,
-                           locale_ref loc = {}) -> OutputIt {
-  if (const_check(!is_supported_floating_point(value))) return out;
-  return specs.localized && write_loc(out, value, specs, loc)
-             ? out
-             : write_float(out, value, specs, loc);
-}
+  SpecHandler& handler;
+};
 
-template <typename Char, typename OutputIt, typename T,
-          FMT_ENABLE_IF(is_fast_float<T>::value)>
-FMT_CONSTEXPR20 auto write(OutputIt out, T value) -> OutputIt {
-  if (is_constant_evaluated()) return write(out, value, format_specs<Char>());
-  if (const_check(!is_supported_floating_point(value))) return out;
+// Adapts SpecHandler to IDHandler API for dynamic precision.
+template <typename SpecHandler, typename Char> struct precision_adapter {
+  explicit FMT_CONSTEXPR precision_adapter(SpecHandler& h) : handler(h) {}
 
-  auto fspecs = float_specs();
-  if (detail::signbit(value)) {
-    fspecs.sign = sign::minus;
-    value = -value;
+  FMT_CONSTEXPR void operator()() { handler.on_dynamic_precision(auto_id()); }
+  FMT_CONSTEXPR void operator()(int id) { handler.on_dynamic_precision(id); }
+  FMT_CONSTEXPR void operator()(basic_string_view<Char> id) {
+    handler.on_dynamic_precision(id);
   }
 
-  constexpr auto specs = format_specs<Char>();
-  using floaty = conditional_t<std::is_same<T, long double>::value, double, T>;
-  using floaty_uint = typename dragonbox::float_info<floaty>::carrier_uint;
-  floaty_uint mask = exponent_mask<floaty>();
-  if ((bit_cast<floaty_uint>(value) & mask) == mask)
-    return write_nonfinite(out, std::isnan(value), specs, fspecs);
+  FMT_CONSTEXPR void on_error(const char* message) {
+    handler.on_error(message);
+  }
 
-  auto dec = dragonbox::to_decimal(static_cast<floaty>(value));
-  return write_float(out, dec, specs, fspecs, {});
-}
+  SpecHandler& handler;
+};
 
-template <typename Char, typename OutputIt, typename T,
-          FMT_ENABLE_IF(is_floating_point<T>::value &&
-                        !is_fast_float<T>::value)>
-inline auto write(OutputIt out, T value) -> OutputIt {
-  return write(out, value, format_specs<Char>());
-}
+template <typename Char>
+FMT_CONSTEXPR int code_point_length(const Char* begin) {
+  if (const_check(sizeof(Char) != 1)) return 1;
+  constexpr char lengths[] = {1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
+                              0, 0, 0, 0, 0, 0, 0, 0, 2, 2, 2, 2, 3, 3, 4, 0};
+  int len = lengths[static_cast<unsigned char>(*begin) >> 3];
 
-template <typename Char, typename OutputIt>
-auto write(OutputIt out, monostate, format_specs<Char> = {}, locale_ref = {})
-    -> OutputIt {
-  FMT_ASSERT(false, "");
-  return out;
+  // Compute the pointer to the next character early so that the next
+  // iteration can start working on the next character. Neither Clang
+  // nor GCC figure out this reordering on their own.
+  return len + !len;
 }
 
-template <typename Char, typename OutputIt>
-FMT_CONSTEXPR auto write(OutputIt out, basic_string_view<Char> value)
-    -> OutputIt {
-  auto it = reserve(out, value.size());
-  it = copy_str_noinline<Char>(value.begin(), value.end(), it);
-  return base_iterator(out, it);
+template <typename Char> constexpr bool is_ascii_letter(Char c) {
+  return (c >= 'a' && c <= 'z') || (c >= 'A' && c <= 'Z');
 }
 
-template <typename Char, typename OutputIt, typename T,
-          FMT_ENABLE_IF(is_string<T>::value)>
-constexpr auto write(OutputIt out, const T& value) -> OutputIt {
-  return write<Char>(out, to_string_view(value));
+// Converts a character to ASCII. Returns a number > 127 on conversion failure.
+template <typename Char, FMT_ENABLE_IF(std::is_integral<Char>::value)>
+constexpr Char to_ascii(Char value) {
+  return value;
 }
-
-// FMT_ENABLE_IF() condition separated to workaround an MSVC bug.
-template <
-    typename Char, typename OutputIt, typename T,
-    bool check =
-        std::is_enum<T>::value && !std::is_same<T, Char>::value &&
-        mapped_type_constant<T, basic_format_context<OutputIt, Char>>::value !=
-            type::custom_type,
-    FMT_ENABLE_IF(check)>
-FMT_CONSTEXPR auto write(OutputIt out, T value) -> OutputIt {
-  return write<Char>(out, static_cast<underlying_t<T>>(value));
+template <typename Char, FMT_ENABLE_IF(std::is_enum<Char>::value)>
+constexpr typename std::underlying_type<Char>::type to_ascii(Char value) {
+  return value;
 }
 
-template <typename Char, typename OutputIt, typename T,
-          FMT_ENABLE_IF(std::is_same<T, bool>::value)>
-FMT_CONSTEXPR auto write(OutputIt out, T value,
-                         const format_specs<Char>& specs = {}, locale_ref = {})
-    -> OutputIt {
-  return specs.type != presentation_type::none &&
-                 specs.type != presentation_type::string
-             ? write(out, value ? 1 : 0, specs, {})
-             : write_bytes(out, value ? "true" : "false", specs);
+// Parses fill and alignment.
+template <typename Char, typename Handler>
+FMT_CONSTEXPR const Char* parse_align(const Char* begin, const Char* end,
+                                      Handler&& handler) {
+  FMT_ASSERT(begin != end, "");
+  auto align = align::none;
+  auto p = begin + code_point_length(begin);
+  if (p >= end) p = begin;
+  for (;;) {
+    switch (to_ascii(*p)) {
+    case '<':
+      align = align::left;
+      break;
+    case '>':
+      align = align::right;
+      break;
+#if FMT_DEPRECATED_NUMERIC_ALIGN
+    case '=':
+      align = align::numeric;
+      break;
+#endif
+    case '^':
+      align = align::center;
+      break;
+    }
+    if (align != align::none) {
+      if (p != begin) {
+        auto c = *begin;
+        if (c == '{')
+          return handler.on_error("invalid fill character '{'"), begin;
+        handler.on_fill(basic_string_view<Char>(begin, to_unsigned(p - begin)));
+        begin = p + 1;
+      } else
+        ++begin;
+      handler.on_align(align);
+      break;
+    } else if (p == begin) {
+      break;
+    }
+    p = begin;
+  }
+  return begin;
 }
 
-template <typename Char, typename OutputIt>
-FMT_CONSTEXPR auto write(OutputIt out, Char value) -> OutputIt {
-  auto it = reserve(out, 1);
-  *it++ = value;
-  return base_iterator(out, it);
+template <typename Char, typename Handler>
+FMT_CONSTEXPR const Char* parse_width(const Char* begin, const Char* end,
+                                      Handler&& handler) {
+  FMT_ASSERT(begin != end, "");
+  if ('0' <= *begin && *begin <= '9') {
+    handler.on_width(parse_nonnegative_int(begin, end, handler));
+  } else if (*begin == '{') {
+    ++begin;
+    if (begin != end)
+      begin = parse_arg_id(begin, end, width_adapter<Handler, Char>(handler));
+    if (begin == end || *begin != '}')
+      return handler.on_error("invalid format string"), begin;
+    ++begin;
+  }
+  return begin;
 }
 
-template <typename Char, typename OutputIt>
-FMT_CONSTEXPR_CHAR_TRAITS auto write(OutputIt out, const Char* value)
-    -> OutputIt {
-  if (value) return write(out, basic_string_view<Char>(value));
-  throw_format_error("string pointer is null");
-  return out;
+template <typename Char, typename Handler>
+FMT_CONSTEXPR const Char* parse_precision(const Char* begin, const Char* end,
+                                          Handler&& handler) {
+  ++begin;
+  auto c = begin != end ? *begin : Char();
+  if ('0' <= c && c <= '9') {
+    handler.on_precision(parse_nonnegative_int(begin, end, handler));
+  } else if (c == '{') {
+    ++begin;
+    if (begin != end) {
+      begin =
+          parse_arg_id(begin, end, precision_adapter<Handler, Char>(handler));
+    }
+    if (begin == end || *begin++ != '}')
+      return handler.on_error("invalid format string"), begin;
+  } else {
+    return handler.on_error("missing precision specifier"), begin;
+  }
+  handler.end_precision();
+  return begin;
 }
 
-template <typename Char, typename OutputIt, typename T,
-          FMT_ENABLE_IF(std::is_same<T, void>::value)>
-auto write(OutputIt out, const T* value, const format_specs<Char>& specs = {},
-           locale_ref = {}) -> OutputIt {
-  return write_ptr<Char>(out, bit_cast<uintptr_t>(value), &specs);
-}
+// Parses standard format specifiers and sends notifications about parsed
+// components to handler.
+template <typename Char, typename SpecHandler>
+FMT_CONSTEXPR const Char* parse_format_specs(const Char* begin, const Char* end,
+                                             SpecHandler&& handler) {
+  if (begin == end) return begin;
 
-// A write overload that handles implicit conversions.
-template <typename Char, typename OutputIt, typename T,
-          typename Context = basic_format_context<OutputIt, Char>>
-FMT_CONSTEXPR auto write(OutputIt out, const T& value) -> enable_if_t<
-    std::is_class<T>::value && !is_string<T>::value &&
-        !is_floating_point<T>::value && !std::is_same<T, Char>::value &&
-        !std::is_same<T, remove_cvref_t<decltype(arg_mapper<Context>().map(
-                             value))>>::value,
-    OutputIt> {
-  return write<Char>(out, arg_mapper<Context>().map(value));
-}
+  begin = parse_align(begin, end, handler);
+  if (begin == end) return begin;
 
-template <typename Char, typename OutputIt, typename T,
-          typename Context = basic_format_context<OutputIt, Char>>
-FMT_CONSTEXPR auto write(OutputIt out, const T& value)
-    -> enable_if_t<mapped_type_constant<T, Context>::value == type::custom_type,
-                   OutputIt> {
-  auto formatter = typename Context::template formatter_type<T>();
-  auto parse_ctx = typename Context::parse_context_type({});
-  formatter.parse(parse_ctx);
-  auto ctx = Context(out, {}, {});
-  return formatter.format(value, ctx);
-}
+  // Parse sign.
+  switch (to_ascii(*begin)) {
+  case '+':
+    handler.on_plus();
+    ++begin;
+    break;
+  case '-':
+    handler.on_minus();
+    ++begin;
+    break;
+  case ' ':
+    handler.on_space();
+    ++begin;
+    break;
+  }
+  if (begin == end) return begin;
 
-// An argument visitor that formats the argument and writes it via the output
-// iterator. It's a class and not a generic lambda for compatibility with C++11.
-template <typename Char> struct default_arg_formatter {
-  using iterator = buffer_appender<Char>;
-  using context = buffer_context<Char>;
+  if (*begin == '#') {
+    handler.on_hash();
+    if (++begin == end) return begin;
+  }
 
-  iterator out;
-  basic_format_args<context> args;
-  locale_ref loc;
+  // Parse zero flag.
+  if (*begin == '0') {
+    handler.on_zero();
+    if (++begin == end) return begin;
+  }
 
-  template <typename T> auto operator()(T value) -> iterator {
-    return write<Char>(out, value);
+  begin = parse_width(begin, end, handler);
+  if (begin == end) return begin;
+
+  // Parse precision.
+  if (*begin == '.') {
+    begin = parse_precision(begin, end, handler);
   }
-  auto operator()(typename basic_format_arg<context>::handle h) -> iterator {
-    basic_format_parse_context<Char> parse_ctx({});
-    context format_ctx(out, args, loc);
-    h.format(parse_ctx, format_ctx);
-    return format_ctx.out();
+
+  // Parse type.
+  if (begin != end && *begin != '}') handler.on_type(*begin++);
+  return begin;
+}
+
+// Return the result via the out param to workaround gcc bug 77539.
+template <bool IS_CONSTEXPR, typename T, typename Ptr = const T*>
+FMT_CONSTEXPR bool find(Ptr first, Ptr last, T value, Ptr& out) {
+  for (out = first; out != last; ++out) {
+    if (*out == value) return true;
   }
-};
+  return false;
+}
 
-template <typename Char> struct arg_formatter {
-  using iterator = buffer_appender<Char>;
-  using context = buffer_context<Char>;
+template <>
+inline bool find<false, char>(const char* first, const char* last, char value,
+                              const char*& out) {
+  out = static_cast<const char*>(
+      std::memchr(first, value, detail::to_unsigned(last - first)));
+  return out != nullptr;
+}
 
-  iterator out;
-  const format_specs<Char>& specs;
-  locale_ref locale;
+template <typename Handler, typename Char> struct id_adapter {
+  Handler& handler;
+  int arg_id;
 
-  template <typename T>
-  FMT_CONSTEXPR FMT_INLINE auto operator()(T value) -> iterator {
-    return detail::write(out, value, specs, locale);
+  FMT_CONSTEXPR void operator()() { arg_id = handler.on_arg_id(); }
+  FMT_CONSTEXPR void operator()(int id) { arg_id = handler.on_arg_id(id); }
+  FMT_CONSTEXPR void operator()(basic_string_view<Char> id) {
+    arg_id = handler.on_arg_id(id);
   }
-  auto operator()(typename basic_format_arg<context>::handle) -> iterator {
-    // User-defined types are handled separately because they require access
-    // to the parse context.
-    return out;
+  FMT_CONSTEXPR void on_error(const char* message) {
+    handler.on_error(message);
   }
 };
 
-template <typename Char> struct custom_formatter {
-  basic_format_parse_context<Char>& parse_ctx;
-  buffer_context<Char>& ctx;
-
-  void operator()(
-      typename basic_format_arg<buffer_context<Char>>::handle h) const {
-    h.format(parse_ctx, ctx);
+template <typename Char, typename Handler>
+FMT_CONSTEXPR const Char* parse_replacement_field(const Char* begin,
+                                                  const Char* end,
+                                                  Handler&& handler) {
+  ++begin;
+  if (begin == end) return handler.on_error("invalid format string"), end;
+  if (*begin == '}') {
+    handler.on_replacement_field(handler.on_arg_id(), begin);
+  } else if (*begin == '{') {
+    handler.on_text(begin, begin + 1);
+  } else {
+    auto adapter = id_adapter<Handler, Char>{handler, 0};
+    begin = parse_arg_id(begin, end, adapter);
+    Char c = begin != end ? *begin : Char();
+    if (c == '}') {
+      handler.on_replacement_field(adapter.arg_id, begin);
+    } else if (c == ':') {
+      begin = handler.on_format_specs(adapter.arg_id, begin + 1, end);
+      if (begin == end || *begin != '}')
+        return handler.on_error("unknown format specifier"), end;
+    } else {
+      return handler.on_error("missing '}' in format string"), end;
+    }
+  }
+  return begin + 1;
+}
+
+template <bool IS_CONSTEXPR, typename Char, typename Handler>
+FMT_CONSTEXPR_DECL FMT_INLINE void parse_format_string(
+    basic_string_view<Char> format_str, Handler&& handler) {
+  auto begin = format_str.data();
+  auto end = begin + format_str.size();
+  if (end - begin < 32) {
+    // Use a simple loop instead of memchr for small strings.
+    const Char* p = begin;
+    while (p != end) {
+      auto c = *p++;
+      if (c == '{') {
+        handler.on_text(begin, p - 1);
+        begin = p = parse_replacement_field(p - 1, end, handler);
+      } else if (c == '}') {
+        if (p == end || *p != '}')
+          return handler.on_error("unmatched '}' in format string");
+        handler.on_text(begin, p);
+        begin = ++p;
+      }
+    }
+    handler.on_text(begin, end);
+    return;
+  }
+  struct writer {
+    FMT_CONSTEXPR void operator()(const Char* pbegin, const Char* pend) {
+      if (pbegin == pend) return;
+      for (;;) {
+        const Char* p = nullptr;
+        if (!find<IS_CONSTEXPR>(pbegin, pend, '}', p))
+          return handler_.on_text(pbegin, pend);
+        ++p;
+        if (p == pend || *p != '}')
+          return handler_.on_error("unmatched '}' in format string");
+        handler_.on_text(pbegin, p);
+        pbegin = p + 1;
+      }
+    }
+    Handler& handler_;
+  } write{handler};
+  while (begin != end) {
+    // Doing two passes with memchr (one for '{' and another for '}') is up to
+    // 2.5x faster than the naive one-pass implementation on big format strings.
+    const Char* p = begin;
+    if (*begin != '{' && !find<IS_CONSTEXPR>(begin + 1, end, '{', p))
+      return write(begin, end);
+    write(begin, p);
+    begin = parse_replacement_field(p, end, handler);
+  }
+}
+
+template <typename T, typename ParseContext>
+FMT_CONSTEXPR const typename ParseContext::char_type* parse_format_specs(
+    ParseContext& ctx) {
+  using char_type = typename ParseContext::char_type;
+  using context = buffer_context<char_type>;
+  using mapped_type =
+      conditional_t<detail::mapped_type_constant<T, context>::value !=
+                        type::custom_type,
+                    decltype(arg_mapper<context>().map(std::declval<T>())), T>;
+  auto f = conditional_t<has_formatter<mapped_type, context>::value,
+                         formatter<mapped_type, char_type>,
+                         detail::fallback_formatter<T, char_type>>();
+  return f.parse(ctx);
+}
+
+template <typename OutputIt, typename Char, typename Context>
+struct format_handler : detail::error_handler {
+  basic_format_parse_context<Char> parse_context;
+  Context context;
+
+  format_handler(OutputIt out, basic_string_view<Char> str,
+                 basic_format_args<Context> format_args, detail::locale_ref loc)
+      : parse_context(str), context(out, format_args, loc) {}
+
+  void on_text(const Char* begin, const Char* end) {
+    auto size = to_unsigned(end - begin);
+    auto out = context.out();
+    auto&& it = reserve(out, size);
+    it = std::copy_n(begin, size, it);
+    context.advance_to(out);
+  }
+
+  int on_arg_id() { return parse_context.next_arg_id(); }
+  int on_arg_id(int id) { return parse_context.check_arg_id(id), id; }
+  int on_arg_id(basic_string_view<Char> id) {
+    int arg_id = context.arg_id(id);
+    if (arg_id < 0) on_error("argument not found");
+    return arg_id;
+  }
+
+  FMT_INLINE void on_replacement_field(int id, const Char*) {
+    auto arg = get_arg(context, id);
+    context.advance_to(visit_format_arg(
+        default_arg_formatter<OutputIt, Char>{context.out(), context.args(),
+                                              context.locale()},
+        arg));
+  }
+
+  const Char* on_format_specs(int id, const Char* begin, const Char* end) {
+    auto arg = get_arg(context, id);
+    if (arg.type() == type::custom_type) {
+      advance_to(parse_context, begin);
+      visit_format_arg(custom_formatter<Context>(parse_context, context), arg);
+      return parse_context.begin();
+    }
+    auto specs = basic_format_specs<Char>();
+    if (begin + 1 < end && begin[1] == '}' && is_ascii_letter(*begin)) {
+      specs.type = static_cast<char>(*begin++);
+    } else {
+      using parse_context_t = basic_format_parse_context<Char>;
+      specs_checker<specs_handler<parse_context_t, Context>> handler(
+          specs_handler<parse_context_t, Context>(specs, parse_context,
+                                                  context),
+          arg.type());
+      begin = parse_format_specs(begin, end, handler);
+      if (begin == end || *begin != '}')
+        on_error("missing '}' in format string");
+    }
+    context.advance_to(visit_format_arg(
+        arg_formatter<OutputIt, Char>(context, &parse_context, &specs), arg));
+    return begin;
   }
-  template <typename T> void operator()(T) const {}
 };
 
-template <typename ErrorHandler> class width_checker {
+// A parse context with extra argument id checks. It is only used at compile
+// time because adding checks at runtime would introduce substantial overhead
+// and would be redundant since argument ids are checked when arguments are
+// retrieved anyway.
+template <typename Char, typename ErrorHandler = error_handler>
+class compile_parse_context
+    : public basic_format_parse_context<Char, ErrorHandler> {
+ private:
+  int num_args_;
+  using base = basic_format_parse_context<Char, ErrorHandler>;
+
  public:
-  explicit FMT_CONSTEXPR width_checker(ErrorHandler& eh) : handler_(eh) {}
+  explicit FMT_CONSTEXPR compile_parse_context(
+      basic_string_view<Char> format_str, int num_args = max_value<int>(),
+      ErrorHandler eh = {})
+      : base(format_str, eh), num_args_(num_args) {}
 
-  template <typename T, FMT_ENABLE_IF(is_integer<T>::value)>
-  FMT_CONSTEXPR auto operator()(T value) -> unsigned long long {
-    if (is_negative(value)) handler_.on_error("negative width");
-    return static_cast<unsigned long long>(value);
+  FMT_CONSTEXPR int next_arg_id() {
+    int id = base::next_arg_id();
+    if (id >= num_args_) this->on_error("argument not found");
+    return id;
   }
 
-  template <typename T, FMT_ENABLE_IF(!is_integer<T>::value)>
-  FMT_CONSTEXPR auto operator()(T) -> unsigned long long {
-    handler_.on_error("width is not integer");
-    return 0;
+  FMT_CONSTEXPR void check_arg_id(int id) {
+    base::check_arg_id(id);
+    if (id >= num_args_) this->on_error("argument not found");
   }
-
- private:
-  ErrorHandler& handler_;
+  using base::check_arg_id;
 };
 
-template <typename ErrorHandler> class precision_checker {
+template <typename Char, typename ErrorHandler, typename... Args>
+class format_string_checker {
  public:
-  explicit FMT_CONSTEXPR precision_checker(ErrorHandler& eh) : handler_(eh) {}
+  explicit FMT_CONSTEXPR format_string_checker(
+      basic_string_view<Char> format_str, ErrorHandler eh)
+      : context_(format_str, num_args, eh),
+        parse_funcs_{&parse_format_specs<Args, parse_context_type>...} {}
 
-  template <typename T, FMT_ENABLE_IF(is_integer<T>::value)>
-  FMT_CONSTEXPR auto operator()(T value) -> unsigned long long {
-    if (is_negative(value)) handler_.on_error("negative precision");
-    return static_cast<unsigned long long>(value);
-  }
+  FMT_CONSTEXPR void on_text(const Char*, const Char*) {}
 
-  template <typename T, FMT_ENABLE_IF(!is_integer<T>::value)>
-  FMT_CONSTEXPR auto operator()(T) -> unsigned long long {
-    handler_.on_error("precision is not integer");
+  FMT_CONSTEXPR int on_arg_id() { return context_.next_arg_id(); }
+  FMT_CONSTEXPR int on_arg_id(int id) { return context_.check_arg_id(id), id; }
+  FMT_CONSTEXPR int on_arg_id(basic_string_view<Char>) {
+    on_error("compile-time checks don't support named arguments");
     return 0;
   }
 
+  FMT_CONSTEXPR void on_replacement_field(int, const Char*) {}
+
+  FMT_CONSTEXPR const Char* on_format_specs(int id, const Char* begin,
+                                            const Char*) {
+    advance_to(context_, begin);
+    return id < num_args ? parse_funcs_[id](context_) : begin;
+  }
+
+  FMT_CONSTEXPR void on_error(const char* message) {
+    context_.on_error(message);
+  }
+
  private:
-  ErrorHandler& handler_;
+  using parse_context_type = compile_parse_context<Char, ErrorHandler>;
+  enum { num_args = sizeof...(Args) };
+
+  // Format specifier parsing function.
+  using parse_func = const Char* (*)(parse_context_type&);
+
+  parse_context_type context_;
+  parse_func parse_funcs_[num_args > 0 ? num_args : 1];
 };
 
-template <template <typename> class Handler, typename FormatArg,
-          typename ErrorHandler>
-FMT_CONSTEXPR auto get_dynamic_spec(FormatArg arg, ErrorHandler eh) -> int {
-  unsigned long long value = visit_format_arg(Handler<ErrorHandler>(eh), arg);
-  if (value > to_unsigned(max_value<int>())) eh.on_error("number is too big");
-  return static_cast<int>(value);
+// Converts string literals to basic_string_view.
+template <typename Char, size_t N>
+FMT_CONSTEXPR basic_string_view<Char> compile_string_to_view(
+    const Char (&s)[N]) {
+  // Remove trailing null character if needed. Won't be present if this is used
+  // with raw character array (i.e. not defined as a string).
+  return {s,
+          N - ((std::char_traits<Char>::to_int_type(s[N - 1]) == 0) ? 1 : 0)};
+}
+
+// Converts string_view to basic_string_view.
+template <typename Char>
+FMT_CONSTEXPR basic_string_view<Char> compile_string_to_view(
+    const std_string_view<Char>& s) {
+  return {s.data(), s.size()};
 }
 
-template <typename Context, typename ID>
-FMT_CONSTEXPR auto get_arg(Context& ctx, ID id) -> decltype(ctx.arg(id)) {
-  auto arg = ctx.arg(id);
-  if (!arg) ctx.on_error("argument not found");
-  return arg;
+#define FMT_STRING_IMPL(s, base)                                  \
+  [] {                                                            \
+    /* Use a macro-like name to avoid shadowing warnings. */      \
+    struct FMT_COMPILE_STRING : base {                            \
+      using char_type = fmt::remove_cvref_t<decltype(s[0])>;      \
+      FMT_MAYBE_UNUSED FMT_CONSTEXPR                              \
+      operator fmt::basic_string_view<char_type>() const {        \
+        return fmt::detail::compile_string_to_view<char_type>(s); \
+      }                                                           \
+    };                                                            \
+    return FMT_COMPILE_STRING();                                  \
+  }()
+
+/**
+  \rst
+  Constructs a compile-time format string from a string literal *s*.
+
+  **Example**::
+
+    // A compile-time error because 'd' is an invalid specifier for strings.
+    std::string s = fmt::format(FMT_STRING("{:d}"), "foo");
+  \endrst
+ */
+#define FMT_STRING(s) FMT_STRING_IMPL(s, fmt::compile_string)
+
+template <typename... Args, typename S,
+          enable_if_t<(is_compile_string<S>::value), int>>
+void check_format_string(S format_str) {
+  FMT_CONSTEXPR_DECL auto s = to_string_view(format_str);
+  using checker = format_string_checker<typename S::char_type, error_handler,
+                                        remove_cvref_t<Args>...>;
+  FMT_CONSTEXPR_DECL bool invalid_format =
+      (parse_format_string<true>(s, checker(s, {})), true);
+  (void)invalid_format;
 }
 
 template <template <typename> class Handler, typename Context>
-FMT_CONSTEXPR void handle_dynamic_spec(int& value,
-                                       arg_ref<typename Context::char_type> ref,
-                                       Context& ctx) {
+void handle_dynamic_spec(int& value, arg_ref<typename Context::char_type> ref,
+                         Context& ctx) {
   switch (ref.kind) {
   case arg_id_kind::none:
     break;
   case arg_id_kind::index:
-    value = detail::get_dynamic_spec<Handler>(get_arg(ctx, ref.val.index),
+    value = detail::get_dynamic_spec<Handler>(ctx.arg(ref.val.index),
                                               ctx.error_handler());
     break;
   case arg_id_kind::name:
-    value = detail::get_dynamic_spec<Handler>(get_arg(ctx, ref.val.name),
+    value = detail::get_dynamic_spec<Handler>(ctx.arg(ref.val.name),
                                               ctx.error_handler());
     break;
   }
 }
 
-#if FMT_USE_USER_DEFINED_LITERALS
-#  if FMT_USE_NONTYPE_TEMPLATE_ARGS
-template <typename T, typename Char, size_t N,
-          fmt::detail_exported::fixed_string<Char, N> Str>
-struct statically_named_arg : view {
-  static constexpr auto name = Str.data;
-
-  const T& value;
-  statically_named_arg(const T& v) : value(v) {}
-};
-
-template <typename T, typename Char, size_t N,
-          fmt::detail_exported::fixed_string<Char, N> Str>
-struct is_named_arg<statically_named_arg<T, Char, N, Str>> : std::true_type {};
-
-template <typename T, typename Char, size_t N,
-          fmt::detail_exported::fixed_string<Char, N> Str>
-struct is_statically_named_arg<statically_named_arg<T, Char, N, Str>>
-    : std::true_type {};
-
-template <typename Char, size_t N,
-          fmt::detail_exported::fixed_string<Char, N> Str>
-struct udl_arg {
-  template <typename T> auto operator=(T&& value) const {
-    return statically_named_arg<T, Char, N, Str>(std::forward<T>(value));
-  }
-};
-#  else
-template <typename Char> struct udl_arg {
-  const Char* str;
-
-  template <typename T> auto operator=(T&& value) const -> named_arg<Char, T> {
-    return {str, std::forward<T>(value)};
-  }
-};
-#  endif
-#endif  // FMT_USE_USER_DEFINED_LITERALS
-
-template <typename Locale, typename Char>
-auto vformat(const Locale& loc, basic_string_view<Char> fmt,
-             basic_format_args<buffer_context<type_identity_t<Char>>> args)
-    -> std::basic_string<Char> {
-  auto buf = basic_memory_buffer<Char>();
-  detail::vformat_to(buf, fmt, args, detail::locale_ref(loc));
-  return {buf.data(), buf.size()};
-}
-
-using format_func = void (*)(detail::buffer<char>&, int, const char*);
+using format_func = void (*)(detail::buffer<char>&, int, string_view);
 
 FMT_API void format_error_code(buffer<char>& out, int error_code,
-                               string_view message) noexcept;
+                               string_view message) FMT_NOEXCEPT;
 
 FMT_API void report_error(format_func func, int error_code,
-                          const char* message) noexcept;
+                          string_view message) FMT_NOEXCEPT;
 }  // namespace detail
 
-FMT_API auto vsystem_error(int error_code, string_view format_str,
-                           format_args args) -> std::system_error;
+template <typename OutputIt, typename Char>
+using arg_formatter FMT_DEPRECATED_ALIAS =
+    detail::arg_formatter<OutputIt, Char>;
 
 /**
-  \rst
-  Constructs :class:`std::system_error` with a message formatted with
-  ``fmt::format(fmt, args...)``.
-  *error_code* is a system error code as given by ``errno``.
+ An error returned by an operating system or a language runtime,
+ for example a file opening error.
+*/
+FMT_CLASS_API
+class FMT_API system_error : public std::runtime_error {
+ private:
+  void init(int err_code, string_view format_str, format_args args);
 
-  **Example**::
+ protected:
+  int error_code_;
 
-    // This throws std::system_error with the description
-    //   cannot open file 'madeup': No such file or directory
-    // or similar (system message may vary).
-    const char* filename = "madeup";
-    std::FILE* file = std::fopen(filename, "r");
-    if (!file)
-      throw fmt::system_error(errno, "cannot open file '{}'", filename);
-  \endrst
- */
-template <typename... T>
-auto system_error(int error_code, format_string<T...> fmt, T&&... args)
-    -> std::system_error {
-  return vsystem_error(error_code, fmt, fmt::make_format_args(args...));
-}
+  system_error() : std::runtime_error(""), error_code_(0) {}
+
+ public:
+  /**
+   \rst
+   Constructs a :class:`fmt::system_error` object with a description
+   formatted with `fmt::format_system_error`. *message* and additional
+   arguments passed into the constructor are formatted similarly to
+   `fmt::format`.
+
+   **Example**::
+
+     // This throws a system_error with the description
+     //   cannot open file 'madeup': No such file or directory
+     // or similar (system message may vary).
+     const char *filename = "madeup";
+     std::FILE *file = std::fopen(filename, "r");
+     if (!file)
+       throw fmt::system_error(errno, "cannot open file '{}'", filename);
+   \endrst
+  */
+  template <typename... Args>
+  system_error(int error_code, string_view message, const Args&... args)
+      : std::runtime_error("") {
+    init(error_code, message, make_format_args(args...));
+  }
+  system_error(const system_error&) = default;
+  system_error& operator=(const system_error&) = default;
+  system_error(system_error&&) = default;
+  system_error& operator=(system_error&&) = default;
+  ~system_error() FMT_NOEXCEPT FMT_OVERRIDE;
+
+  int error_code() const { return error_code_; }
+};
 
 /**
   \rst
-  Formats an error message for an error returned by an operating system or a
-  language runtime, for example a file opening error, and writes it to *out*.
-  The format is the same as the one used by ``std::system_error(ec, message)``
-  where ``ec`` is ``std::error_code(error_code, std::generic_category()})``.
-  It is implementation-defined but normally looks like:
+  Formats an error returned by an operating system or a language runtime,
+  for example a file opening error, and writes it to *out* in the following
+  form:
 
   .. parsed-literal::
      *<message>*: *<system-message>*
 
-  where *<message>* is the passed message and *<system-message>* is the system
-  message corresponding to the error code.
+  where *<message>* is the passed message and *<system-message>* is
+  the system message corresponding to the error code.
   *error_code* is a system error code as given by ``errno``.
+  If *error_code* is not a valid error code such as -1, the system message
+  may look like "Unknown error -1" and is platform-dependent.
   \endrst
  */
 FMT_API void format_system_error(detail::buffer<char>& out, int error_code,
-                                 const char* message) noexcept;
+                                 string_view message) FMT_NOEXCEPT;
 
 // Reports a system error without throwing an exception.
 // Can be used to report errors from destructors.
-FMT_API void report_system_error(int error_code, const char* message) noexcept;
+FMT_API void report_system_error(int error_code,
+                                 string_view message) FMT_NOEXCEPT;
 
 /** Fast integer formatter. */
 class format_int {
@@ -4005,12 +3339,12 @@ class format_int {
   mutable char buffer_[buffer_size];
   char* str_;
 
-  template <typename UInt> auto format_unsigned(UInt value) -> char* {
+  template <typename UInt> char* format_unsigned(UInt value) {
     auto n = static_cast<detail::uint32_or_64_or_128_t<UInt>>(value);
     return detail::format_decimal(buffer_, n, buffer_size - 1).begin;
   }
 
-  template <typename Int> auto format_signed(Int value) -> char* {
+  template <typename Int> char* format_signed(Int value) {
     auto abs_value = static_cast<detail::uint32_or_64_or_128_t<Int>>(value);
     bool negative = value < 0;
     if (negative) abs_value = 0 - abs_value;
@@ -4029,7 +3363,7 @@ class format_int {
       : str_(format_unsigned(value)) {}
 
   /** Returns the number of characters written to the output buffer. */
-  auto size() const -> size_t {
+  size_t size() const {
     return detail::to_unsigned(buffer_ - str_ + buffer_size - 1);
   }
 
@@ -4037,13 +3371,13 @@ class format_int {
     Returns a pointer to the output buffer content. No terminating null
     character is appended.
    */
-  auto data() const -> const char* { return str_; }
+  const char* data() const { return str_; }
 
   /**
     Returns a pointer to the output buffer content with terminating null
     character appended.
    */
-  auto c_str() const -> const char* {
+  const char* c_str() const {
     buffer_[buffer_size - 1] = '\0';
     return str_;
   }
@@ -4053,83 +3387,226 @@ class format_int {
     Returns the content of the output buffer as an ``std::string``.
     \endrst
    */
-  auto str() const -> std::string { return std::string(str_, size()); }
+  std::string str() const { return std::string(str_, size()); }
 };
 
+// A formatter specialization for the core types corresponding to detail::type
+// constants.
 template <typename T, typename Char>
-struct formatter<T, Char, enable_if_t<detail::has_format_as<T>::value>>
-    : private formatter<detail::format_as_t<T>, Char> {
-  using base = formatter<detail::format_as_t<T>, Char>;
-  using base::parse;
-  using base::set_debug_format;
+struct formatter<T, Char,
+                 enable_if_t<detail::type_constant<T, Char>::value !=
+                             detail::type::custom_type>> {
+  FMT_CONSTEXPR formatter() = default;
+
+  // Parses format specifiers stopping either at the end of the range or at the
+  // terminating '}'.
+  template <typename ParseContext>
+  FMT_CONSTEXPR auto parse(ParseContext& ctx) -> decltype(ctx.begin()) {
+    using handler_type = detail::dynamic_specs_handler<ParseContext>;
+    auto type = detail::type_constant<T, Char>::value;
+    detail::specs_checker<handler_type> handler(handler_type(specs_, ctx),
+                                                type);
+    auto it = parse_format_specs(ctx.begin(), ctx.end(), handler);
+    auto eh = ctx.error_handler();
+    switch (type) {
+    case detail::type::none_type:
+      FMT_ASSERT(false, "invalid argument type");
+      break;
+    case detail::type::int_type:
+    case detail::type::uint_type:
+    case detail::type::long_long_type:
+    case detail::type::ulong_long_type:
+    case detail::type::int128_type:
+    case detail::type::uint128_type:
+    case detail::type::bool_type:
+      handle_int_type_spec(specs_.type,
+                           detail::int_type_checker<decltype(eh)>(eh));
+      break;
+    case detail::type::char_type:
+      handle_char_specs(
+          &specs_, detail::char_specs_checker<decltype(eh)>(specs_.type, eh));
+      break;
+    case detail::type::float_type:
+      if (detail::const_check(FMT_USE_FLOAT))
+        detail::parse_float_type_spec(specs_, eh);
+      else
+        FMT_ASSERT(false, "float support disabled");
+      break;
+    case detail::type::double_type:
+      if (detail::const_check(FMT_USE_DOUBLE))
+        detail::parse_float_type_spec(specs_, eh);
+      else
+        FMT_ASSERT(false, "double support disabled");
+      break;
+    case detail::type::long_double_type:
+      if (detail::const_check(FMT_USE_LONG_DOUBLE))
+        detail::parse_float_type_spec(specs_, eh);
+      else
+        FMT_ASSERT(false, "long double support disabled");
+      break;
+    case detail::type::cstring_type:
+      detail::handle_cstring_type_spec(
+          specs_.type, detail::cstring_type_checker<decltype(eh)>(eh));
+      break;
+    case detail::type::string_type:
+      detail::check_string_type_spec(specs_.type, eh);
+      break;
+    case detail::type::pointer_type:
+      detail::check_pointer_type_spec(specs_.type, eh);
+      break;
+    case detail::type::custom_type:
+      // Custom format specifiers should be checked in parse functions of
+      // formatter specializations.
+      break;
+    }
+    return it;
+  }
 
   template <typename FormatContext>
-  auto format(const T& value, FormatContext& ctx) const -> decltype(ctx.out()) {
-    return base::format(format_as(value), ctx);
+  auto format(const T& val, FormatContext& ctx) -> decltype(ctx.out()) {
+    detail::handle_dynamic_spec<detail::width_checker>(specs_.width,
+                                                       specs_.width_ref, ctx);
+    detail::handle_dynamic_spec<detail::precision_checker>(
+        specs_.precision, specs_.precision_ref, ctx);
+    using af = detail::arg_formatter<typename FormatContext::iterator,
+                                     typename FormatContext::char_type>;
+    return visit_format_arg(af(ctx, nullptr, &specs_),
+                            detail::make_arg<FormatContext>(val));
   }
+
+ private:
+  detail::dynamic_format_specs<Char> specs_;
 };
 
-#define FMT_FORMAT_AS(Type, Base) \
-  template <typename Char>        \
-  struct formatter<Type, Char> : formatter<Base, Char> {}
+#define FMT_FORMAT_AS(Type, Base)                                             \
+  template <typename Char>                                                    \
+  struct formatter<Type, Char> : formatter<Base, Char> {                      \
+    template <typename FormatContext>                                         \
+    auto format(Type const& val, FormatContext& ctx) -> decltype(ctx.out()) { \
+      return formatter<Base, Char>::format(val, ctx);                         \
+    }                                                                         \
+  }
 
 FMT_FORMAT_AS(signed char, int);
 FMT_FORMAT_AS(unsigned char, unsigned);
 FMT_FORMAT_AS(short, int);
 FMT_FORMAT_AS(unsigned short, unsigned);
-FMT_FORMAT_AS(long, detail::long_type);
-FMT_FORMAT_AS(unsigned long, detail::ulong_type);
+FMT_FORMAT_AS(long, long long);
+FMT_FORMAT_AS(unsigned long, unsigned long long);
 FMT_FORMAT_AS(Char*, const Char*);
 FMT_FORMAT_AS(std::basic_string<Char>, basic_string_view<Char>);
 FMT_FORMAT_AS(std::nullptr_t, const void*);
 FMT_FORMAT_AS(detail::std_string_view<Char>, basic_string_view<Char>);
-FMT_FORMAT_AS(void*, const void*);
+
+template <typename Char>
+struct formatter<void*, Char> : formatter<const void*, Char> {
+  template <typename FormatContext>
+  auto format(void* val, FormatContext& ctx) -> decltype(ctx.out()) {
+    return formatter<const void*, Char>::format(val, ctx);
+  }
+};
 
 template <typename Char, size_t N>
-struct formatter<Char[N], Char> : formatter<basic_string_view<Char>, Char> {};
+struct formatter<Char[N], Char> : formatter<basic_string_view<Char>, Char> {
+  template <typename FormatContext>
+  auto format(const Char* val, FormatContext& ctx) -> decltype(ctx.out()) {
+    return formatter<basic_string_view<Char>, Char>::format(val, ctx);
+  }
+};
 
-/**
-  \rst
-  Converts ``p`` to ``const void*`` for pointer formatting.
+// A formatter for types known only at run time such as variant alternatives.
+//
+// Usage:
+//   using variant = std::variant<int, std::string>;
+//   template <>
+//   struct formatter<variant>: dynamic_formatter<> {
+//     auto format(const variant& v, format_context& ctx) {
+//       return visit([&](const auto& val) {
+//           return dynamic_formatter<>::format(val, ctx);
+//       }, v);
+//     }
+//   };
+template <typename Char = char> class dynamic_formatter {
+ private:
+  struct null_handler : detail::error_handler {
+    void on_align(align_t) {}
+    void on_plus() {}
+    void on_minus() {}
+    void on_space() {}
+    void on_hash() {}
+  };
 
-  **Example**::
+ public:
+  template <typename ParseContext>
+  auto parse(ParseContext& ctx) -> decltype(ctx.begin()) {
+    format_str_ = ctx.begin();
+    // Checks are deferred to formatting time when the argument type is known.
+    detail::dynamic_specs_handler<ParseContext> handler(specs_, ctx);
+    return parse_format_specs(ctx.begin(), ctx.end(), handler);
+  }
+
+  template <typename T, typename FormatContext>
+  auto format(const T& val, FormatContext& ctx) -> decltype(ctx.out()) {
+    handle_specs(ctx);
+    detail::specs_checker<null_handler> checker(
+        null_handler(), detail::mapped_type_constant<T, FormatContext>::value);
+    checker.on_align(specs_.align);
+    switch (specs_.sign) {
+    case sign::none:
+      break;
+    case sign::plus:
+      checker.on_plus();
+      break;
+    case sign::minus:
+      checker.on_minus();
+      break;
+    case sign::space:
+      checker.on_space();
+      break;
+    }
+    if (specs_.alt) checker.on_hash();
+    if (specs_.precision >= 0) checker.end_precision();
+    using af = detail::arg_formatter<typename FormatContext::iterator,
+                                     typename FormatContext::char_type>;
+    visit_format_arg(af(ctx, nullptr, &specs_),
+                     detail::make_arg<FormatContext>(val));
+    return ctx.out();
+  }
 
-    auto s = fmt::format("{}", fmt::ptr(p));
-  \endrst
- */
-template <typename T> auto ptr(T p) -> const void* {
-  static_assert(std::is_pointer<T>::value, "");
-  return detail::bit_cast<const void*>(p);
-}
-template <typename T, typename Deleter>
-auto ptr(const std::unique_ptr<T, Deleter>& p) -> const void* {
-  return p.get();
-}
-template <typename T> auto ptr(const std::shared_ptr<T>& p) -> const void* {
-  return p.get();
+ private:
+  template <typename Context> void handle_specs(Context& ctx) {
+    detail::handle_dynamic_spec<detail::width_checker>(specs_.width,
+                                                       specs_.width_ref, ctx);
+    detail::handle_dynamic_spec<detail::precision_checker>(
+        specs_.precision, specs_.precision_ref, ctx);
+  }
+
+  detail::dynamic_format_specs<Char> specs_;
+  const Char* format_str_;
+};
+
+template <typename Char, typename ErrorHandler>
+FMT_CONSTEXPR void advance_to(
+    basic_format_parse_context<Char, ErrorHandler>& ctx, const Char* p) {
+  ctx.advance_to(ctx.begin() + (p - &*ctx.begin()));
 }
 
 /**
   \rst
-  Converts ``e`` to the underlying type.
+  Converts ``p`` to ``const void*`` for pointer formatting.
 
   **Example**::
 
-    enum class color { red, green, blue };
-    auto s = fmt::format("{}", fmt::underlying(color::red));
+    auto s = fmt::format("{}", fmt::ptr(p));
   \endrst
  */
-template <typename Enum>
-constexpr auto underlying(Enum e) noexcept -> underlying_t<Enum> {
-  return static_cast<underlying_t<Enum>>(e);
+template <typename T> inline const void* ptr(const T* p) { return p; }
+template <typename T> inline const void* ptr(const std::unique_ptr<T>& p) {
+  return p.get();
 }
-
-namespace enums {
-template <typename Enum, FMT_ENABLE_IF(std::is_enum<Enum>::value)>
-constexpr auto format_as(Enum e) noexcept -> underlying_t<Enum> {
-  return static_cast<underlying_t<Enum>>(e);
+template <typename T> inline const void* ptr(const std::shared_ptr<T>& p) {
+  return p.get();
 }
-}  // namespace enums
 
 class bytes {
  private:
@@ -4142,13 +3619,17 @@ class bytes {
 
 template <> struct formatter<bytes> {
  private:
-  detail::dynamic_format_specs<> specs_;
+  detail::dynamic_format_specs<char> specs_;
 
  public:
   template <typename ParseContext>
-  FMT_CONSTEXPR auto parse(ParseContext& ctx) -> const char* {
-    return parse_format_specs(ctx.begin(), ctx.end(), specs_, ctx,
-                              detail::type::string_type);
+  FMT_CONSTEXPR auto parse(ParseContext& ctx) -> decltype(ctx.begin()) {
+    using handler_type = detail::dynamic_specs_handler<ParseContext>;
+    detail::specs_checker<handler_type> handler(handler_type(specs_, ctx),
+                                                detail::type::string_type);
+    auto it = parse_format_specs(ctx.begin(), ctx.end(), handler);
+    detail::check_string_type_spec(specs_.type, ctx.error_handler());
+    return it;
   }
 
   template <typename FormatContext>
@@ -4161,144 +3642,31 @@ template <> struct formatter<bytes> {
   }
 };
 
-// group_digits_view is not derived from view because it copies the argument.
-template <typename T> struct group_digits_view {
-  T value;
-};
-
-/**
-  \rst
-  Returns a view that formats an integer value using ',' as a locale-independent
-  thousands separator.
-
-  **Example**::
-
-    fmt::print("{}", fmt::group_digits(12345));
-    // Output: "12,345"
-  \endrst
- */
-template <typename T> auto group_digits(T value) -> group_digits_view<T> {
-  return {value};
-}
-
-template <typename T> struct formatter<group_digits_view<T>> : formatter<T> {
- private:
-  detail::dynamic_format_specs<> specs_;
-
- public:
-  template <typename ParseContext>
-  FMT_CONSTEXPR auto parse(ParseContext& ctx) -> const char* {
-    return parse_format_specs(ctx.begin(), ctx.end(), specs_, ctx,
-                              detail::type::int_type);
-  }
-
-  template <typename FormatContext>
-  auto format(group_digits_view<T> t, FormatContext& ctx)
-      -> decltype(ctx.out()) {
-    detail::handle_dynamic_spec<detail::width_checker>(specs_.width,
-                                                       specs_.width_ref, ctx);
-    detail::handle_dynamic_spec<detail::precision_checker>(
-        specs_.precision, specs_.precision_ref, ctx);
-    return detail::write_int(
-        ctx.out(), static_cast<detail::uint64_or_128_t<T>>(t.value), 0, specs_,
-        detail::digit_grouping<char>("\3", ","));
-  }
-};
-
-template <typename T> struct nested_view {
-  const formatter<T>* fmt;
-  const T* value;
-};
-
-template <typename T> struct formatter<nested_view<T>> {
-  FMT_CONSTEXPR auto parse(format_parse_context& ctx) -> const char* {
-    return ctx.begin();
-  }
-  auto format(nested_view<T> view, format_context& ctx) const
-      -> decltype(ctx.out()) {
-    return view.fmt->format(*view.value, ctx);
-  }
-};
-
-template <typename T> struct nested_formatter {
- private:
-  int width_;
-  detail::fill_t<char> fill_;
-  align_t align_ : 4;
-  formatter<T> formatter_;
-
- public:
-  constexpr nested_formatter() : width_(0), align_(align_t::none) {}
-
-  FMT_CONSTEXPR auto parse(format_parse_context& ctx) -> const char* {
-    auto specs = detail::dynamic_format_specs<char>();
-    auto it = parse_format_specs(ctx.begin(), ctx.end(), specs, ctx,
-                                 detail::type::none_type);
-    width_ = specs.width;
-    fill_ = specs.fill;
-    align_ = specs.align;
-    ctx.advance_to(it);
-    return formatter_.parse(ctx);
-  }
-
-  template <typename F>
-  auto write_padded(format_context& ctx, F write) const -> decltype(ctx.out()) {
-    if (width_ == 0) return write(ctx.out());
-    auto buf = memory_buffer();
-    write(std::back_inserter(buf));
-    auto specs = format_specs<>();
-    specs.width = width_;
-    specs.fill = fill_;
-    specs.align = align_;
-    return detail::write(ctx.out(), string_view(buf.data(), buf.size()), specs);
-  }
-
-  auto nested(const T& value) const -> nested_view<T> {
-    return nested_view<T>{&formatter_, &value};
-  }
-};
-
-// DEPRECATED! join_view will be moved to ranges.h.
-template <typename It, typename Sentinel, typename Char = char>
-struct join_view : detail::view {
+template <typename It, typename Sentinel, typename Char>
+struct arg_join : detail::view {
   It begin;
   Sentinel end;
   basic_string_view<Char> sep;
 
-  join_view(It b, Sentinel e, basic_string_view<Char> s)
+  arg_join(It b, Sentinel e, basic_string_view<Char> s)
       : begin(b), end(e), sep(s) {}
 };
 
 template <typename It, typename Sentinel, typename Char>
-struct formatter<join_view<It, Sentinel, Char>, Char> {
- private:
-  using value_type =
-#ifdef __cpp_lib_ranges
-      std::iter_value_t<It>;
-#else
-      typename std::iterator_traits<It>::value_type;
-#endif
-  formatter<remove_cvref_t<value_type>, Char> value_formatter_;
-
- public:
-  template <typename ParseContext>
-  FMT_CONSTEXPR auto parse(ParseContext& ctx) -> const Char* {
-    return value_formatter_.parse(ctx);
-  }
-
+struct formatter<arg_join<It, Sentinel, Char>, Char>
+    : formatter<typename std::iterator_traits<It>::value_type, Char> {
   template <typename FormatContext>
-  auto format(const join_view<It, Sentinel, Char>& value,
-              FormatContext& ctx) const -> decltype(ctx.out()) {
+  auto format(const arg_join<It, Sentinel, Char>& value, FormatContext& ctx)
+      -> decltype(ctx.out()) {
+    using base = formatter<typename std::iterator_traits<It>::value_type, Char>;
     auto it = value.begin;
     auto out = ctx.out();
     if (it != value.end) {
-      out = value_formatter_.format(*it, ctx);
-      ++it;
+      out = base::format(*it++, ctx);
       while (it != value.end) {
-        out = detail::copy_str<Char>(value.sep.begin(), value.sep.end(), out);
+        out = std::copy(value.sep.begin(), value.sep.end(), out);
         ctx.advance_to(out);
-        out = value_formatter_.format(*it, ctx);
-        ++it;
+        out = base::format(*it++, ctx);
       }
     }
     return out;
@@ -4306,17 +3674,22 @@ struct formatter<join_view<It, Sentinel, Char>, Char> {
 };
 
 /**
-  Returns a view that formats the iterator range `[begin, end)` with elements
+  Returns an object that formats the iterator range `[begin, end)` with elements
   separated by `sep`.
  */
 template <typename It, typename Sentinel>
-auto join(It begin, Sentinel end, string_view sep) -> join_view<It, Sentinel> {
+arg_join<It, Sentinel, char> join(It begin, Sentinel end, string_view sep) {
+  return {begin, end, sep};
+}
+
+template <typename It, typename Sentinel>
+arg_join<It, Sentinel, wchar_t> join(It begin, Sentinel end, wstring_view sep) {
   return {begin, end, sep};
 }
 
 /**
   \rst
-  Returns a view that formats `range` with elements separated by `sep`.
+  Returns an object that formats `range` with elements separated by `sep`.
 
   **Example**::
 
@@ -4331,8 +3704,14 @@ auto join(It begin, Sentinel end, string_view sep) -> join_view<It, Sentinel> {
   \endrst
  */
 template <typename Range>
-auto join(Range&& range, string_view sep)
-    -> join_view<detail::iterator_t<Range>, detail::sentinel_t<Range>> {
+arg_join<detail::iterator_t<Range>, detail::sentinel_t<Range>, char> join(
+    Range&& range, string_view sep) {
+  return join(std::begin(range), std::end(range), sep);
+}
+
+template <typename Range>
+arg_join<detail::iterator_t<Range>, detail::sentinel_t<Range>, wchar_t> join(
+    Range&& range, wstring_view sep) {
   return join(std::begin(range), std::end(range), sep);
 }
 
@@ -4342,222 +3721,233 @@ auto join(Range&& range, string_view sep)
 
   **Example**::
 
-    #include <fmt/format.h>
+    #include <fmt-vt/format.h>
 
     std::string answer = fmt::to_string(42);
   \endrst
  */
-template <typename T, FMT_ENABLE_IF(!std::is_integral<T>::value &&
-                                    !detail::has_format_as<T>::value)>
-inline auto to_string(const T& value) -> std::string {
-  auto buffer = memory_buffer();
-  detail::write<char>(appender(buffer), value);
-  return {buffer.data(), buffer.size()};
+template <typename T, FMT_ENABLE_IF(!std::is_integral<T>::value)>
+inline std::string to_string(const T& value) {
+  std::string result;
+  detail::write<char>(std::back_inserter(result), value);
+  return result;
 }
 
 template <typename T, FMT_ENABLE_IF(std::is_integral<T>::value)>
-FMT_NODISCARD inline auto to_string(T value) -> std::string {
-  // The buffer should be large enough to store the number including the sign
-  // or "false" for bool.
+inline std::string to_string(T value) {
+  // The buffer should be large enough to store the number including the sign or
+  // "false" for bool.
   constexpr int max_size = detail::digits10<T>() + 2;
   char buffer[max_size > 5 ? static_cast<unsigned>(max_size) : 5];
   char* begin = buffer;
   return std::string(begin, detail::write<char>(begin, value));
 }
 
+/**
+  Converts *value* to ``std::wstring`` using the default format for type *T*.
+ */
+template <typename T> inline std::wstring to_wstring(const T& value) {
+  return format(L"{}", value);
+}
+
 template <typename Char, size_t SIZE>
-FMT_NODISCARD auto to_string(const basic_memory_buffer<Char, SIZE>& buf)
-    -> std::basic_string<Char> {
+std::basic_string<Char> to_string(const basic_memory_buffer<Char, SIZE>& buf) {
   auto size = buf.size();
   detail::assume(size < std::basic_string<Char>().max_size());
   return std::basic_string<Char>(buf.data(), size);
 }
 
-template <typename T, FMT_ENABLE_IF(!std::is_integral<T>::value &&
-                                    detail::has_format_as<T>::value)>
-inline auto to_string(const T& value) -> std::string {
-  return to_string(format_as(value));
-}
-
-FMT_END_EXPORT
-
-namespace detail {
-
 template <typename Char>
-void vformat_to(buffer<Char>& buf, basic_string_view<Char> fmt,
-                typename vformat_args<Char>::type args, locale_ref loc) {
+void detail::vformat_to(
+    detail::buffer<Char>& buf, basic_string_view<Char> format_str,
+    basic_format_args<buffer_context<type_identity_t<Char>>> args,
+    detail::locale_ref loc) {
+  using iterator = typename buffer_context<Char>::iterator;
   auto out = buffer_appender<Char>(buf);
-  if (fmt.size() == 2 && equal2(fmt.data(), "{}")) {
+  if (format_str.size() == 2 && equal2(format_str.data(), "{}")) {
     auto arg = args.get(0);
     if (!arg) error_handler().on_error("argument not found");
-    visit_format_arg(default_arg_formatter<Char>{out, args, loc}, arg);
+    visit_format_arg(default_arg_formatter<iterator, Char>{out, args, loc},
+                     arg);
     return;
   }
+  format_handler<iterator, Char, buffer_context<Char>> h(out, format_str, args,
+                                                         loc);
+  parse_format_string<false>(format_str, h);
+}
 
-  struct format_handler : error_handler {
-    basic_format_parse_context<Char> parse_context;
-    buffer_context<Char> context;
+#ifndef FMT_HEADER_ONLY
+extern template void detail::vformat_to(detail::buffer<char>&, string_view,
+                                        basic_format_args<format_context>,
+                                        detail::locale_ref);
+namespace detail {
 
-    format_handler(buffer_appender<Char> p_out, basic_string_view<Char> str,
-                   basic_format_args<buffer_context<Char>> p_args,
-                   locale_ref p_loc)
-        : parse_context(str), context(p_out, p_args, p_loc) {}
+extern template FMT_API std::string grouping_impl<char>(locale_ref loc);
+extern template FMT_API std::string grouping_impl<wchar_t>(locale_ref loc);
+extern template FMT_API char thousands_sep_impl<char>(locale_ref loc);
+extern template FMT_API wchar_t thousands_sep_impl<wchar_t>(locale_ref loc);
+extern template FMT_API char decimal_point_impl(locale_ref loc);
+extern template FMT_API wchar_t decimal_point_impl(locale_ref loc);
+extern template int format_float<double>(double value, int precision,
+                                         float_specs specs, buffer<char>& buf);
+extern template int format_float<long double>(long double value, int precision,
+                                              float_specs specs,
+                                              buffer<char>& buf);
+int snprintf_float(float value, int precision, float_specs specs,
+                   buffer<char>& buf) = delete;
+extern template int snprintf_float<double>(double value, int precision,
+                                           float_specs specs,
+                                           buffer<char>& buf);
+extern template int snprintf_float<long double>(long double value,
+                                                int precision,
+                                                float_specs specs,
+                                                buffer<char>& buf);
+}  // namespace detail
+#endif
 
-    void on_text(const Char* begin, const Char* end) {
-      auto text = basic_string_view<Char>(begin, to_unsigned(end - begin));
-      context.advance_to(write<Char>(context.out(), text));
-    }
+template <typename S, typename Char = char_t<S>,
+          FMT_ENABLE_IF(detail::is_string<S>::value)>
+inline void vformat_to(
+    detail::buffer<Char>& buf, const S& format_str,
+    basic_format_args<FMT_BUFFER_CONTEXT(type_identity_t<Char>)> args) {
+  return detail::vformat_to(buf, to_string_view(format_str), args);
+}
 
-    FMT_CONSTEXPR auto on_arg_id() -> int {
-      return parse_context.next_arg_id();
-    }
-    FMT_CONSTEXPR auto on_arg_id(int id) -> int {
-      return parse_context.check_arg_id(id), id;
-    }
-    FMT_CONSTEXPR auto on_arg_id(basic_string_view<Char> id) -> int {
-      int arg_id = context.arg_id(id);
-      if (arg_id < 0) on_error("argument not found");
-      return arg_id;
-    }
+template <typename S, typename... Args, size_t SIZE = inline_buffer_size,
+          typename Char = enable_if_t<detail::is_string<S>::value, char_t<S>>>
+inline typename buffer_context<Char>::iterator format_to(
+    basic_memory_buffer<Char, SIZE>& buf, const S& format_str, Args&&... args) {
+  const auto& vargs = fmt::make_args_checked<Args...>(format_str, args...);
+  detail::vformat_to(buf, to_string_view(format_str), vargs);
+  return detail::buffer_appender<Char>(buf);
+}
 
-    FMT_INLINE void on_replacement_field(int id, const Char*) {
-      auto arg = get_arg(context, id);
-      context.advance_to(visit_format_arg(
-          default_arg_formatter<Char>{context.out(), context.args(),
-                                      context.locale()},
-          arg));
-    }
+template <typename OutputIt, typename Char = char>
+using format_context_t = basic_format_context<OutputIt, Char>;
 
-    auto on_format_specs(int id, const Char* begin, const Char* end)
-        -> const Char* {
-      auto arg = get_arg(context, id);
-      if (arg.type() == type::custom_type) {
-        parse_context.advance_to(begin);
-        visit_format_arg(custom_formatter<Char>{parse_context, context}, arg);
-        return parse_context.begin();
-      }
-      auto specs = detail::dynamic_format_specs<Char>();
-      begin = parse_format_specs(begin, end, specs, parse_context, arg.type());
-      detail::handle_dynamic_spec<detail::width_checker>(
-          specs.width, specs.width_ref, context);
-      detail::handle_dynamic_spec<detail::precision_checker>(
-          specs.precision, specs.precision_ref, context);
-      if (begin == end || *begin != '}')
-        on_error("missing '}' in format string");
-      auto f = arg_formatter<Char>{context.out(), specs, context.locale()};
-      context.advance_to(visit_format_arg(f, arg));
-      return begin;
-    }
-  };
-  detail::parse_format_string<false>(fmt, format_handler(out, fmt, args, loc));
+template <typename OutputIt, typename Char = char>
+using format_args_t = basic_format_args<format_context_t<OutputIt, Char>>;
+
+template <typename OutputIt, typename Char = typename OutputIt::value_type>
+using format_to_n_context FMT_DEPRECATED_ALIAS = buffer_context<Char>;
+
+template <typename OutputIt, typename Char = typename OutputIt::value_type>
+using format_to_n_args FMT_DEPRECATED_ALIAS =
+    basic_format_args<buffer_context<Char>>;
+
+template <typename OutputIt, typename Char, typename... Args>
+FMT_DEPRECATED format_arg_store<buffer_context<Char>, Args...>
+make_format_to_n_args(const Args&... args) {
+  return format_arg_store<buffer_context<Char>, Args...>(args...);
 }
 
-FMT_BEGIN_EXPORT
+template <typename Char, enable_if_t<(!std::is_same<Char, char>::value), int>>
+std::basic_string<Char> detail::vformat(
+    basic_string_view<Char> format_str,
+    basic_format_args<buffer_context<type_identity_t<Char>>> args) {
+  basic_memory_buffer<Char> buffer;
+  detail::vformat_to(buffer, format_str, args);
+  return to_string(buffer);
+}
 
-#ifndef FMT_HEADER_ONLY
-extern template FMT_API void vformat_to(buffer<char>&, string_view,
-                                        typename vformat_args<>::type,
-                                        locale_ref);
-extern template FMT_API auto thousands_sep_impl<char>(locale_ref)
-    -> thousands_sep_result<char>;
-extern template FMT_API auto thousands_sep_impl<wchar_t>(locale_ref)
-    -> thousands_sep_result<wchar_t>;
-extern template FMT_API auto decimal_point_impl(locale_ref) -> char;
-extern template FMT_API auto decimal_point_impl(locale_ref) -> wchar_t;
-#endif  // FMT_HEADER_ONLY
+template <typename Char, FMT_ENABLE_IF(std::is_same<Char, wchar_t>::value)>
+void vprint(std::FILE* f, basic_string_view<Char> format_str,
+            wformat_args args) {
+  wmemory_buffer buffer;
+  detail::vformat_to(buffer, format_str, args);
+  buffer.push_back(L'\0');
+  if (std::fputws(buffer.data(), f) == -1)
+    FMT_THROW(system_error(errno, "cannot write to file"));
+}
 
-}  // namespace detail
+template <typename Char, FMT_ENABLE_IF(std::is_same<Char, wchar_t>::value)>
+void vprint(basic_string_view<Char> format_str, wformat_args args) {
+  vprint(stdout, format_str, args);
+}
 
 #if FMT_USE_USER_DEFINED_LITERALS
+namespace detail {
+
+#  if FMT_USE_UDL_TEMPLATE
+template <typename Char, Char... CHARS> class udl_formatter {
+ public:
+  template <typename... Args>
+  std::basic_string<Char> operator()(Args&&... args) const {
+    static FMT_CONSTEXPR_DECL Char s[] = {CHARS..., '\0'};
+    return format(FMT_STRING(s), std::forward<Args>(args)...);
+  }
+};
+#  else
+template <typename Char> struct udl_formatter {
+  basic_string_view<Char> str;
+
+  template <typename... Args>
+  std::basic_string<Char> operator()(Args&&... args) const {
+    return format(str, std::forward<Args>(args)...);
+  }
+};
+#  endif  // FMT_USE_UDL_TEMPLATE
+
+template <typename Char> struct udl_arg {
+  const Char* str;
+
+  template <typename T> named_arg<Char, T> operator=(T&& value) const {
+    return {str, std::forward<T>(value)};
+  }
+};
+}  // namespace detail
+
 inline namespace literals {
+#  if FMT_USE_UDL_TEMPLATE
+#    pragma GCC diagnostic push
+#    pragma GCC diagnostic ignored "-Wpedantic"
+#    if FMT_CLANG_VERSION
+#      pragma GCC diagnostic ignored "-Wgnu-string-literal-operator-template"
+#    endif
+template <typename Char, Char... CHARS>
+FMT_CONSTEXPR detail::udl_formatter<Char, CHARS...> operator""_format() {
+  return {};
+}
+#    pragma GCC diagnostic pop
+#  else
 /**
   \rst
-  User-defined literal equivalent of :func:`fmt::arg`.
+  User-defined literal equivalent of :func:`fmt::format`.
 
   **Example**::
 
     using namespace fmt::literals;
-    fmt::print("Elapsed time: {s:.2f} seconds", "s"_a=1.23);
+    std::string message = "The answer is {}"_format(42);
   \endrst
  */
-#  if FMT_USE_NONTYPE_TEMPLATE_ARGS
-template <detail_exported::fixed_string Str> constexpr auto operator""_a() {
-  using char_t = remove_cvref_t<decltype(Str.data[0])>;
-  return detail::udl_arg<char_t, sizeof(Str.data) / sizeof(char_t), Str>();
-}
-#  else
-constexpr auto operator""_a(const char* s, size_t) -> detail::udl_arg<char> {
-  return {s};
-}
-#  endif
-}  // namespace literals
-#endif  // FMT_USE_USER_DEFINED_LITERALS
-
-template <typename Locale, FMT_ENABLE_IF(detail::is_locale<Locale>::value)>
-inline auto vformat(const Locale& loc, string_view fmt, format_args args)
-    -> std::string {
-  return detail::vformat(loc, fmt, args);
+FMT_CONSTEXPR detail::udl_formatter<char> operator"" _format(const char* s,
+                                                             size_t n) {
+  return {{s, n}};
 }
-
-template <typename Locale, typename... T,
-          FMT_ENABLE_IF(detail::is_locale<Locale>::value)>
-inline auto format(const Locale& loc, format_string<T...> fmt, T&&... args)
-    -> std::string {
-  return fmt::vformat(loc, string_view(fmt), fmt::make_format_args(args...));
+FMT_CONSTEXPR detail::udl_formatter<wchar_t> operator"" _format(
+    const wchar_t* s, size_t n) {
+  return {{s, n}};
 }
+#  endif  // FMT_USE_UDL_TEMPLATE
 
-template <typename OutputIt, typename Locale,
-          FMT_ENABLE_IF(detail::is_output_iterator<OutputIt, char>::value&&
-                            detail::is_locale<Locale>::value)>
-auto vformat_to(OutputIt out, const Locale& loc, string_view fmt,
-                format_args args) -> OutputIt {
-  using detail::get_buffer;
-  auto&& buf = get_buffer<char>(out);
-  detail::vformat_to(buf, fmt, args, detail::locale_ref(loc));
-  return detail::get_iterator(buf, out);
-}
+/**
+  \rst
+  User-defined literal equivalent of :func:`fmt::arg`.
 
-template <typename OutputIt, typename Locale, typename... T,
-          FMT_ENABLE_IF(detail::is_output_iterator<OutputIt, char>::value&&
-                            detail::is_locale<Locale>::value)>
-FMT_INLINE auto format_to(OutputIt out, const Locale& loc,
-                          format_string<T...> fmt, T&&... args) -> OutputIt {
-  return vformat_to(out, loc, fmt, fmt::make_format_args(args...));
-}
+  **Example**::
 
-template <typename Locale, typename... T,
-          FMT_ENABLE_IF(detail::is_locale<Locale>::value)>
-FMT_NODISCARD FMT_INLINE auto formatted_size(const Locale& loc,
-                                             format_string<T...> fmt,
-                                             T&&... args) -> size_t {
-  auto buf = detail::counting_buffer<>();
-  detail::vformat_to<char>(buf, fmt, fmt::make_format_args(args...),
-                           detail::locale_ref(loc));
-  return buf.count();
+    using namespace fmt::literals;
+    fmt::print("Elapsed time: {s:.2f} seconds", "s"_a=1.23);
+  \endrst
+ */
+FMT_CONSTEXPR detail::udl_arg<char> operator"" _a(const char* s, size_t) {
+  return {s};
 }
-
-FMT_END_EXPORT
-
-template <typename T, typename Char>
-template <typename FormatContext>
-FMT_CONSTEXPR FMT_INLINE auto
-formatter<T, Char,
-          enable_if_t<detail::type_constant<T, Char>::value !=
-                      detail::type::custom_type>>::format(const T& val,
-                                                          FormatContext& ctx)
-    const -> decltype(ctx.out()) {
-  if (specs_.width_ref.kind != detail::arg_id_kind::none ||
-      specs_.precision_ref.kind != detail::arg_id_kind::none) {
-    auto specs = specs_;
-    detail::handle_dynamic_spec<detail::width_checker>(specs.width,
-                                                       specs.width_ref, ctx);
-    detail::handle_dynamic_spec<detail::precision_checker>(
-        specs.precision, specs.precision_ref, ctx);
-    return detail::write<Char>(ctx.out(), val, specs, ctx.locale());
-  }
-  return detail::write<Char>(ctx.out(), val, specs_, ctx.locale());
+FMT_CONSTEXPR detail::udl_arg<wchar_t> operator"" _a(const wchar_t* s, size_t) {
+  return {s};
 }
-
+}  // namespace literals
+#endif  // FMT_USE_USER_DEFINED_LITERALS
 FMT_END_NAMESPACE
 
 #ifdef FMT_HEADER_ONLY
diff --git a/lib/fmt/include/fmt-vt/ostream.h b/lib/fmt/include/fmt-vt/ostream.h
index 782ace5cc3..29c58ec13b 100644
--- a/lib/fmt/include/fmt-vt/ostream.h
+++ b/lib/fmt/include/fmt-vt/ostream.h
@@ -8,74 +8,87 @@
 #ifndef FMT_OSTREAM_H_
 #define FMT_OSTREAM_H_
 
-#include <fstream>  // std::filebuf
-
-#ifdef _WIN32
-#  ifdef __GLIBCXX__
-#    include <ext/stdio_filebuf.h>
-#    include <ext/stdio_sync_filebuf.h>
-#  endif
-#  include <io.h>
-#endif
+#include <ostream>
 
 #include "format.h"
 
 FMT_BEGIN_NAMESPACE
 
+template <typename Char> class basic_printf_parse_context;
+template <typename OutputIt, typename Char> class basic_printf_context;
+
 namespace detail {
 
-// Generate a unique explicit instantion in every translation unit using a tag
-// type in an anonymous namespace.
-namespace {
-struct file_access_tag {};
-}  // namespace
-template <typename Tag, typename BufType, FILE* BufType::*FileMemberPtr>
-class file_access {
-  friend auto get_file(BufType& obj) -> FILE* { return obj.*FileMemberPtr; }
-};
+template <class Char> class formatbuf : public std::basic_streambuf<Char> {
+ private:
+  using int_type = typename std::basic_streambuf<Char>::int_type;
+  using traits_type = typename std::basic_streambuf<Char>::traits_type;
 
-#if FMT_MSC_VERSION
-template class file_access<file_access_tag, std::filebuf,
-                           &std::filebuf::_Myfile>;
-auto get_file(std::filebuf&) -> FILE*;
-#endif
+  buffer<Char>& buffer_;
 
-inline bool write_ostream_unicode(std::ostream& os, fmt::string_view data) {
-  FILE* f = nullptr;
-#if FMT_MSC_VERSION
-  if (auto* buf = dynamic_cast<std::filebuf*>(os.rdbuf()))
-    f = get_file(*buf);
-  else
-    return false;
-#elif defined(_WIN32) && defined(__GLIBCXX__)
-  auto* rdbuf = os.rdbuf();
-  if (auto* sfbuf = dynamic_cast<__gnu_cxx::stdio_sync_filebuf<char>*>(rdbuf))
-    f = sfbuf->file();
-  else if (auto* fbuf = dynamic_cast<__gnu_cxx::stdio_filebuf<char>*>(rdbuf))
-    f = fbuf->file();
-  else
-    return false;
-#else
-  ignore_unused(os, data, f);
-#endif
-#ifdef _WIN32
-  if (f) {
-    int fd = _fileno(f);
-    if (_isatty(fd)) {
-      os.flush();
-      return write_console(fd, data);
-    }
+ public:
+  formatbuf(buffer<Char>& buf) : buffer_(buf) {}
+
+ protected:
+  // The put-area is actually always empty. This makes the implementation
+  // simpler and has the advantage that the streambuf and the buffer are always
+  // in sync and sputc never writes into uninitialized memory. The obvious
+  // disadvantage is that each call to sputc always results in a (virtual) call
+  // to overflow. There is no disadvantage here for sputn since this always
+  // results in a call to xsputn.
+
+  int_type overflow(int_type ch = traits_type::eof()) FMT_OVERRIDE {
+    if (!traits_type::eq_int_type(ch, traits_type::eof()))
+      buffer_.push_back(static_cast<Char>(ch));
+    return ch;
   }
-#endif
-  return false;
-}
-inline bool write_ostream_unicode(std::wostream&,
-                                  fmt::basic_string_view<wchar_t>) {
-  return false;
-}
+
+  std::streamsize xsputn(const Char* s, std::streamsize count) FMT_OVERRIDE {
+    buffer_.append(s, s + count);
+    return count;
+  }
+};
+
+struct converter {
+  template <typename T, FMT_ENABLE_IF(is_integral<T>::value)> converter(T);
+};
+
+template <typename Char> struct test_stream : std::basic_ostream<Char> {
+ private:
+  void_t<> operator<<(converter);
+};
+
+// Hide insertion operators for built-in types.
+template <typename Char, typename Traits>
+void_t<> operator<<(std::basic_ostream<Char, Traits>&, Char);
+template <typename Char, typename Traits>
+void_t<> operator<<(std::basic_ostream<Char, Traits>&, char);
+template <typename Traits>
+void_t<> operator<<(std::basic_ostream<char, Traits>&, char);
+template <typename Traits>
+void_t<> operator<<(std::basic_ostream<char, Traits>&, signed char);
+template <typename Traits>
+void_t<> operator<<(std::basic_ostream<char, Traits>&, unsigned char);
+
+// Checks if T has a user-defined operator<< (e.g. not a member of
+// std::ostream).
+template <typename T, typename Char> class is_streamable {
+ private:
+  template <typename U>
+  static bool_constant<!std::is_same<decltype(std::declval<test_stream<Char>&>()
+                                              << std::declval<U>()),
+                                     void_t<>>::value>
+  test(int);
+
+  template <typename> static std::false_type test(...);
+
+  using result = decltype(test<T>(0));
+
+ public:
+  static const bool value = result::value;
+};
 
 // Write the content of buf to os.
-// It is a separate function rather than a part of vprint to simplify testing.
 template <typename Char>
 void write_buffer(std::basic_ostream<Char>& os, buffer<Char>& buf) {
   const Char* buf_data = buf.data();
@@ -93,81 +106,54 @@ void write_buffer(std::basic_ostream<Char>& os, buffer<Char>& buf) {
 template <typename Char, typename T>
 void format_value(buffer<Char>& buf, const T& value,
                   locale_ref loc = locale_ref()) {
-  auto&& format_buf = formatbuf<std::basic_streambuf<Char>>(buf);
-  auto&& output = std::basic_ostream<Char>(&format_buf);
+  formatbuf<Char> format_buf(buf);
+  std::basic_ostream<Char> output(&format_buf);
 #if !defined(FMT_STATIC_THOUSANDS_SEPARATOR)
   if (loc) output.imbue(loc.get<std::locale>());
 #endif
   output << value;
   output.exceptions(std::ios_base::failbit | std::ios_base::badbit);
+  buf.try_resize(buf.size());
 }
 
-template <typename T> struct streamed_view {
-  const T& value;
-};
-
-}  // namespace detail
-
 // Formats an object of type T that has an overloaded ostream operator<<.
-template <typename Char>
-struct basic_ostream_formatter : formatter<basic_string_view<Char>, Char> {
-  void set_debug_format() = delete;
+template <typename T, typename Char>
+struct fallback_formatter<T, Char, enable_if_t<is_streamable<T, Char>::value>>
+    : private formatter<basic_string_view<Char>, Char> {
+  FMT_CONSTEXPR auto parse(basic_format_parse_context<Char>& ctx)
+      -> decltype(ctx.begin()) {
+    return formatter<basic_string_view<Char>, Char>::parse(ctx);
+  }
+  template <typename ParseCtx,
+            FMT_ENABLE_IF(std::is_same<
+                          ParseCtx, basic_printf_parse_context<Char>>::value)>
+  auto parse(ParseCtx& ctx) -> decltype(ctx.begin()) {
+    return ctx.begin();
+  }
 
-  template <typename T, typename OutputIt>
-  auto format(const T& value, basic_format_context<OutputIt, Char>& ctx) const
+  template <typename OutputIt>
+  auto format(const T& value, basic_format_context<OutputIt, Char>& ctx)
       -> OutputIt {
-    auto buffer = basic_memory_buffer<Char>();
-    detail::format_value(buffer, value, ctx.locale());
-    return formatter<basic_string_view<Char>, Char>::format(
-        {buffer.data(), buffer.size()}, ctx);
+    basic_memory_buffer<Char> buffer;
+    format_value(buffer, value, ctx.locale());
+    basic_string_view<Char> str(buffer.data(), buffer.size());
+    return formatter<basic_string_view<Char>, Char>::format(str, ctx);
   }
-};
-
-using ostream_formatter = basic_ostream_formatter<char>;
-
-template <typename T, typename Char>
-struct formatter<detail::streamed_view<T>, Char>
-    : basic_ostream_formatter<Char> {
   template <typename OutputIt>
-  auto format(detail::streamed_view<T> view,
-              basic_format_context<OutputIt, Char>& ctx) const -> OutputIt {
-    return basic_ostream_formatter<Char>::format(view.value, ctx);
+  auto format(const T& value, basic_printf_context<OutputIt, Char>& ctx)
+      -> OutputIt {
+    basic_memory_buffer<Char> buffer;
+    format_value(buffer, value, ctx.locale());
+    return std::copy(buffer.begin(), buffer.end(), ctx.out());
   }
 };
-
-/**
-  \rst
-  Returns a view that formats `value` via an ostream ``operator<<``.
-
-  **Example**::
-
-    fmt::print("Current thread id: {}\n",
-               fmt::streamed(std::this_thread::get_id()));
-  \endrst
- */
-template <typename T>
-constexpr auto streamed(const T& value) -> detail::streamed_view<T> {
-  return {value};
-}
-
-namespace detail {
-
-inline void vprint_directly(std::ostream& os, string_view format_str,
-                            format_args args) {
-  auto buffer = memory_buffer();
-  detail::vformat_to(buffer, format_str, args);
-  detail::write_buffer(os, buffer);
-}
-
 }  // namespace detail
 
-FMT_EXPORT template <typename Char>
-void vprint(std::basic_ostream<Char>& os,
-            basic_string_view<type_identity_t<Char>> format_str,
+template <typename Char>
+void vprint(std::basic_ostream<Char>& os, basic_string_view<Char> format_str,
             basic_format_args<buffer_context<type_identity_t<Char>>> args) {
-  auto buffer = basic_memory_buffer<Char>();
+  basic_memory_buffer<Char> buffer;
   detail::vformat_to(buffer, format_str, args);
-  if (detail::write_ostream_unicode(os, {buffer.data(), buffer.size()})) return;
   detail::write_buffer(os, buffer);
 }
 
@@ -180,36 +166,12 @@ void vprint(std::basic_ostream<Char>& os,
     fmt::print(cerr, "Don't {}!", "panic");
   \endrst
  */
-FMT_EXPORT template <typename... T>
-void print(std::ostream& os, format_string<T...> fmt, T&&... args) {
-  const auto& vargs = fmt::make_format_args(args...);
-  if (detail::is_utf8())
-    vprint(os, fmt, vargs);
-  else
-    detail::vprint_directly(os, fmt, vargs);
+template <typename S, typename... Args,
+          typename Char = enable_if_t<detail::is_string<S>::value, char_t<S>>>
+void print(std::basic_ostream<Char>& os, const S& format_str, Args&&... args) {
+  vprint(os, to_string_view(format_str),
+         fmt::make_args_checked<Args...>(format_str, args...));
 }
-
-FMT_EXPORT
-template <typename... Args>
-void print(std::wostream& os,
-           basic_format_string<wchar_t, type_identity_t<Args>...> fmt,
-           Args&&... args) {
-  vprint(os, fmt, fmt::make_format_args<buffer_context<wchar_t>>(args...));
-}
-
-FMT_EXPORT template <typename... T>
-void println(std::ostream& os, format_string<T...> fmt, T&&... args) {
-  fmt::print(os, "{}\n", fmt::format(fmt, std::forward<T>(args)...));
-}
-
-FMT_EXPORT
-template <typename... Args>
-void println(std::wostream& os,
-             basic_format_string<wchar_t, type_identity_t<Args>...> fmt,
-             Args&&... args) {
-  print(os, L"{}\n", fmt::format(fmt, std::forward<Args>(args)...));
-}
-
 FMT_END_NAMESPACE
 
 #endif  // FMT_OSTREAM_H_
diff --git a/lib/fmt/include/fmt-vt/printf.h b/lib/fmt/include/fmt-vt/printf.h
deleted file mode 100644
index 07e81577cf..0000000000
--- a/lib/fmt/include/fmt-vt/printf.h
+++ /dev/null
@@ -1,675 +0,0 @@
-// Formatting library for C++ - legacy printf implementation
-//
-// Copyright (c) 2012 - 2016, Victor Zverovich
-// All rights reserved.
-//
-// For the license information refer to format.h.
-
-#ifndef FMT_PRINTF_H_
-#define FMT_PRINTF_H_
-
-#include <algorithm>  // std::max
-#include <limits>     // std::numeric_limits
-
-#include "format.h"
-
-FMT_BEGIN_NAMESPACE
-FMT_BEGIN_EXPORT
-
-template <typename T> struct printf_formatter {
-  printf_formatter() = delete;
-};
-
-template <typename Char> class basic_printf_context {
- private:
-  detail::buffer_appender<Char> out_;
-  basic_format_args<basic_printf_context> args_;
-
-  static_assert(std::is_same<Char, char>::value ||
-                    std::is_same<Char, wchar_t>::value,
-                "Unsupported code unit type.");
-
- public:
-  using char_type = Char;
-  using parse_context_type = basic_format_parse_context<Char>;
-  template <typename T> using formatter_type = printf_formatter<T>;
-
-  /**
-    \rst
-    Constructs a ``printf_context`` object. References to the arguments are
-    stored in the context object so make sure they have appropriate lifetimes.
-    \endrst
-   */
-  basic_printf_context(detail::buffer_appender<Char> out,
-                       basic_format_args<basic_printf_context> args)
-      : out_(out), args_(args) {}
-
-  auto out() -> detail::buffer_appender<Char> { return out_; }
-  void advance_to(detail::buffer_appender<Char>) {}
-
-  auto locale() -> detail::locale_ref { return {}; }
-
-  auto arg(int id) const -> basic_format_arg<basic_printf_context> {
-    return args_.get(id);
-  }
-
-  FMT_CONSTEXPR void on_error(const char* message) {
-    detail::error_handler().on_error(message);
-  }
-};
-
-namespace detail {
-
-// Checks if a value fits in int - used to avoid warnings about comparing
-// signed and unsigned integers.
-template <bool IsSigned> struct int_checker {
-  template <typename T> static auto fits_in_int(T value) -> bool {
-    unsigned max = max_value<int>();
-    return value <= max;
-  }
-  static auto fits_in_int(bool) -> bool { return true; }
-};
-
-template <> struct int_checker<true> {
-  template <typename T> static auto fits_in_int(T value) -> bool {
-    return value >= (std::numeric_limits<int>::min)() &&
-           value <= max_value<int>();
-  }
-  static auto fits_in_int(int) -> bool { return true; }
-};
-
-struct printf_precision_handler {
-  template <typename T, FMT_ENABLE_IF(std::is_integral<T>::value)>
-  auto operator()(T value) -> int {
-    if (!int_checker<std::numeric_limits<T>::is_signed>::fits_in_int(value))
-      throw_format_error("number is too big");
-    return (std::max)(static_cast<int>(value), 0);
-  }
-
-  template <typename T, FMT_ENABLE_IF(!std::is_integral<T>::value)>
-  auto operator()(T) -> int {
-    throw_format_error("precision is not integer");
-    return 0;
-  }
-};
-
-// An argument visitor that returns true iff arg is a zero integer.
-struct is_zero_int {
-  template <typename T, FMT_ENABLE_IF(std::is_integral<T>::value)>
-  auto operator()(T value) -> bool {
-    return value == 0;
-  }
-
-  template <typename T, FMT_ENABLE_IF(!std::is_integral<T>::value)>
-  auto operator()(T) -> bool {
-    return false;
-  }
-};
-
-template <typename T> struct make_unsigned_or_bool : std::make_unsigned<T> {};
-
-template <> struct make_unsigned_or_bool<bool> {
-  using type = bool;
-};
-
-template <typename T, typename Context> class arg_converter {
- private:
-  using char_type = typename Context::char_type;
-
-  basic_format_arg<Context>& arg_;
-  char_type type_;
-
- public:
-  arg_converter(basic_format_arg<Context>& arg, char_type type)
-      : arg_(arg), type_(type) {}
-
-  void operator()(bool value) {
-    if (type_ != 's') operator()<bool>(value);
-  }
-
-  template <typename U, FMT_ENABLE_IF(std::is_integral<U>::value)>
-  void operator()(U value) {
-    bool is_signed = type_ == 'd' || type_ == 'i';
-    using target_type = conditional_t<std::is_same<T, void>::value, U, T>;
-    if (const_check(sizeof(target_type) <= sizeof(int))) {
-      // Extra casts are used to silence warnings.
-      if (is_signed) {
-        auto n = static_cast<int>(static_cast<target_type>(value));
-        arg_ = detail::make_arg<Context>(n);
-      } else {
-        using unsigned_type = typename make_unsigned_or_bool<target_type>::type;
-        auto n = static_cast<unsigned>(static_cast<unsigned_type>(value));
-        arg_ = detail::make_arg<Context>(n);
-      }
-    } else {
-      if (is_signed) {
-        // glibc's printf doesn't sign extend arguments of smaller types:
-        //   std::printf("%lld", -42);  // prints "4294967254"
-        // but we don't have to do the same because it's a UB.
-        auto n = static_cast<long long>(value);
-        arg_ = detail::make_arg<Context>(n);
-      } else {
-        auto n = static_cast<typename make_unsigned_or_bool<U>::type>(value);
-        arg_ = detail::make_arg<Context>(n);
-      }
-    }
-  }
-
-  template <typename U, FMT_ENABLE_IF(!std::is_integral<U>::value)>
-  void operator()(U) {}  // No conversion needed for non-integral types.
-};
-
-// Converts an integer argument to T for printf, if T is an integral type.
-// If T is void, the argument is converted to corresponding signed or unsigned
-// type depending on the type specifier: 'd' and 'i' - signed, other -
-// unsigned).
-template <typename T, typename Context, typename Char>
-void convert_arg(basic_format_arg<Context>& arg, Char type) {
-  visit_format_arg(arg_converter<T, Context>(arg, type), arg);
-}
-
-// Converts an integer argument to char for printf.
-template <typename Context> class char_converter {
- private:
-  basic_format_arg<Context>& arg_;
-
- public:
-  explicit char_converter(basic_format_arg<Context>& arg) : arg_(arg) {}
-
-  template <typename T, FMT_ENABLE_IF(std::is_integral<T>::value)>
-  void operator()(T value) {
-    auto c = static_cast<typename Context::char_type>(value);
-    arg_ = detail::make_arg<Context>(c);
-  }
-
-  template <typename T, FMT_ENABLE_IF(!std::is_integral<T>::value)>
-  void operator()(T) {}  // No conversion needed for non-integral types.
-};
-
-// An argument visitor that return a pointer to a C string if argument is a
-// string or null otherwise.
-template <typename Char> struct get_cstring {
-  template <typename T> auto operator()(T) -> const Char* { return nullptr; }
-  auto operator()(const Char* s) -> const Char* { return s; }
-};
-
-// Checks if an argument is a valid printf width specifier and sets
-// left alignment if it is negative.
-template <typename Char> class printf_width_handler {
- private:
-  format_specs<Char>& specs_;
-
- public:
-  explicit printf_width_handler(format_specs<Char>& specs) : specs_(specs) {}
-
-  template <typename T, FMT_ENABLE_IF(std::is_integral<T>::value)>
-  auto operator()(T value) -> unsigned {
-    auto width = static_cast<uint32_or_64_or_128_t<T>>(value);
-    if (detail::is_negative(value)) {
-      specs_.align = align::left;
-      width = 0 - width;
-    }
-    unsigned int_max = max_value<int>();
-    if (width > int_max) throw_format_error("number is too big");
-    return static_cast<unsigned>(width);
-  }
-
-  template <typename T, FMT_ENABLE_IF(!std::is_integral<T>::value)>
-  auto operator()(T) -> unsigned {
-    throw_format_error("width is not integer");
-    return 0;
-  }
-};
-
-// Workaround for a bug with the XL compiler when initializing
-// printf_arg_formatter's base class.
-template <typename Char>
-auto make_arg_formatter(buffer_appender<Char> iter, format_specs<Char>& s)
-    -> arg_formatter<Char> {
-  return {iter, s, locale_ref()};
-}
-
-// The ``printf`` argument formatter.
-template <typename Char>
-class printf_arg_formatter : public arg_formatter<Char> {
- private:
-  using base = arg_formatter<Char>;
-  using context_type = basic_printf_context<Char>;
-
-  context_type& context_;
-
-  void write_null_pointer(bool is_string = false) {
-    auto s = this->specs;
-    s.type = presentation_type::none;
-    write_bytes(this->out, is_string ? "(null)" : "(nil)", s);
-  }
-
- public:
-  printf_arg_formatter(buffer_appender<Char> iter, format_specs<Char>& s,
-                       context_type& ctx)
-      : base(make_arg_formatter(iter, s)), context_(ctx) {}
-
-  void operator()(monostate value) { base::operator()(value); }
-
-  template <typename T, FMT_ENABLE_IF(detail::is_integral<T>::value)>
-  void operator()(T value) {
-    // MSVC2013 fails to compile separate overloads for bool and Char so use
-    // std::is_same instead.
-    if (!std::is_same<T, Char>::value) {
-      base::operator()(value);
-      return;
-    }
-    format_specs<Char> fmt_specs = this->specs;
-    if (fmt_specs.type != presentation_type::none &&
-        fmt_specs.type != presentation_type::chr) {
-      return (*this)(static_cast<int>(value));
-    }
-    fmt_specs.sign = sign::none;
-    fmt_specs.alt = false;
-    fmt_specs.fill[0] = ' ';  // Ignore '0' flag for char types.
-    // align::numeric needs to be overwritten here since the '0' flag is
-    // ignored for non-numeric types
-    if (fmt_specs.align == align::none || fmt_specs.align == align::numeric)
-      fmt_specs.align = align::right;
-    write<Char>(this->out, static_cast<Char>(value), fmt_specs);
-  }
-
-  template <typename T, FMT_ENABLE_IF(std::is_floating_point<T>::value)>
-  void operator()(T value) {
-    base::operator()(value);
-  }
-
-  /** Formats a null-terminated C string. */
-  void operator()(const char* value) {
-    if (value)
-      base::operator()(value);
-    else
-      write_null_pointer(this->specs.type != presentation_type::pointer);
-  }
-
-  /** Formats a null-terminated wide C string. */
-  void operator()(const wchar_t* value) {
-    if (value)
-      base::operator()(value);
-    else
-      write_null_pointer(this->specs.type != presentation_type::pointer);
-  }
-
-  void operator()(basic_string_view<Char> value) { base::operator()(value); }
-
-  /** Formats a pointer. */
-  void operator()(const void* value) {
-    if (value)
-      base::operator()(value);
-    else
-      write_null_pointer();
-  }
-
-  /** Formats an argument of a custom (user-defined) type. */
-  void operator()(typename basic_format_arg<context_type>::handle handle) {
-    auto parse_ctx = basic_format_parse_context<Char>({});
-    handle.format(parse_ctx, context_);
-  }
-};
-
-template <typename Char>
-void parse_flags(format_specs<Char>& specs, const Char*& it, const Char* end) {
-  for (; it != end; ++it) {
-    switch (*it) {
-    case '-':
-      specs.align = align::left;
-      break;
-    case '+':
-      specs.sign = sign::plus;
-      break;
-    case '0':
-      specs.fill[0] = '0';
-      break;
-    case ' ':
-      if (specs.sign != sign::plus) specs.sign = sign::space;
-      break;
-    case '#':
-      specs.alt = true;
-      break;
-    default:
-      return;
-    }
-  }
-}
-
-template <typename Char, typename GetArg>
-auto parse_header(const Char*& it, const Char* end, format_specs<Char>& specs,
-                  GetArg get_arg) -> int {
-  int arg_index = -1;
-  Char c = *it;
-  if (c >= '0' && c <= '9') {
-    // Parse an argument index (if followed by '$') or a width possibly
-    // preceded with '0' flag(s).
-    int value = parse_nonnegative_int(it, end, -1);
-    if (it != end && *it == '$') {  // value is an argument index
-      ++it;
-      arg_index = value != -1 ? value : max_value<int>();
-    } else {
-      if (c == '0') specs.fill[0] = '0';
-      if (value != 0) {
-        // Nonzero value means that we parsed width and don't need to
-        // parse it or flags again, so return now.
-        if (value == -1) throw_format_error("number is too big");
-        specs.width = value;
-        return arg_index;
-      }
-    }
-  }
-  parse_flags(specs, it, end);
-  // Parse width.
-  if (it != end) {
-    if (*it >= '0' && *it <= '9') {
-      specs.width = parse_nonnegative_int(it, end, -1);
-      if (specs.width == -1) throw_format_error("number is too big");
-    } else if (*it == '*') {
-      ++it;
-      specs.width = static_cast<int>(visit_format_arg(
-          detail::printf_width_handler<Char>(specs), get_arg(-1)));
-    }
-  }
-  return arg_index;
-}
-
-inline auto parse_printf_presentation_type(char c, type t)
-    -> presentation_type {
-  using pt = presentation_type;
-  constexpr auto integral_set = sint_set | uint_set | bool_set | char_set;
-  switch (c) {
-  case 'd':
-    return in(t, integral_set) ? pt::dec : pt::none;
-  case 'o':
-    return in(t, integral_set) ? pt::oct : pt::none;
-  case 'x':
-    return in(t, integral_set) ? pt::hex_lower : pt::none;
-  case 'X':
-    return in(t, integral_set) ? pt::hex_upper : pt::none;
-  case 'a':
-    return in(t, float_set) ? pt::hexfloat_lower : pt::none;
-  case 'A':
-    return in(t, float_set) ? pt::hexfloat_upper : pt::none;
-  case 'e':
-    return in(t, float_set) ? pt::exp_lower : pt::none;
-  case 'E':
-    return in(t, float_set) ? pt::exp_upper : pt::none;
-  case 'f':
-    return in(t, float_set) ? pt::fixed_lower : pt::none;
-  case 'F':
-    return in(t, float_set) ? pt::fixed_upper : pt::none;
-  case 'g':
-    return in(t, float_set) ? pt::general_lower : pt::none;
-  case 'G':
-    return in(t, float_set) ? pt::general_upper : pt::none;
-  case 'c':
-    return in(t, integral_set) ? pt::chr : pt::none;
-  case 's':
-    return in(t, string_set | cstring_set) ? pt::string : pt::none;
-  case 'p':
-    return in(t, pointer_set | cstring_set) ? pt::pointer : pt::none;
-  default:
-    return pt::none;
-  }
-}
-
-template <typename Char, typename Context>
-void vprintf(buffer<Char>& buf, basic_string_view<Char> format,
-             basic_format_args<Context> args) {
-  using iterator = buffer_appender<Char>;
-  auto out = iterator(buf);
-  auto context = basic_printf_context<Char>(out, args);
-  auto parse_ctx = basic_format_parse_context<Char>(format);
-
-  // Returns the argument with specified index or, if arg_index is -1, the next
-  // argument.
-  auto get_arg = [&](int arg_index) {
-    if (arg_index < 0)
-      arg_index = parse_ctx.next_arg_id();
-    else
-      parse_ctx.check_arg_id(--arg_index);
-    return detail::get_arg(context, arg_index);
-  };
-
-  const Char* start = parse_ctx.begin();
-  const Char* end = parse_ctx.end();
-  auto it = start;
-  while (it != end) {
-    if (!find<false, Char>(it, end, '%', it)) {
-      it = end;  // find leaves it == nullptr if it doesn't find '%'.
-      break;
-    }
-    Char c = *it++;
-    if (it != end && *it == c) {
-      write(out, basic_string_view<Char>(start, to_unsigned(it - start)));
-      start = ++it;
-      continue;
-    }
-    write(out, basic_string_view<Char>(start, to_unsigned(it - 1 - start)));
-
-    auto specs = format_specs<Char>();
-    specs.align = align::right;
-
-    // Parse argument index, flags and width.
-    int arg_index = parse_header(it, end, specs, get_arg);
-    if (arg_index == 0) throw_format_error("argument not found");
-
-    // Parse precision.
-    if (it != end && *it == '.') {
-      ++it;
-      c = it != end ? *it : 0;
-      if ('0' <= c && c <= '9') {
-        specs.precision = parse_nonnegative_int(it, end, 0);
-      } else if (c == '*') {
-        ++it;
-        specs.precision = static_cast<int>(
-            visit_format_arg(printf_precision_handler(), get_arg(-1)));
-      } else {
-        specs.precision = 0;
-      }
-    }
-
-    auto arg = get_arg(arg_index);
-    // For d, i, o, u, x, and X conversion specifiers, if a precision is
-    // specified, the '0' flag is ignored
-    if (specs.precision >= 0 && arg.is_integral()) {
-      // Ignore '0' for non-numeric types or if '-' present.
-      specs.fill[0] = ' ';
-    }
-    if (specs.precision >= 0 && arg.type() == type::cstring_type) {
-      auto str = visit_format_arg(get_cstring<Char>(), arg);
-      auto str_end = str + specs.precision;
-      auto nul = std::find(str, str_end, Char());
-      auto sv = basic_string_view<Char>(
-          str, to_unsigned(nul != str_end ? nul - str : specs.precision));
-      arg = make_arg<basic_printf_context<Char>>(sv);
-    }
-    if (specs.alt && visit_format_arg(is_zero_int(), arg)) specs.alt = false;
-    if (specs.fill[0] == '0') {
-      if (arg.is_arithmetic() && specs.align != align::left)
-        specs.align = align::numeric;
-      else
-        specs.fill[0] = ' ';  // Ignore '0' flag for non-numeric types or if '-'
-                              // flag is also present.
-    }
-
-    // Parse length and convert the argument to the required type.
-    c = it != end ? *it++ : 0;
-    Char t = it != end ? *it : 0;
-    switch (c) {
-    case 'h':
-      if (t == 'h') {
-        ++it;
-        t = it != end ? *it : 0;
-        convert_arg<signed char>(arg, t);
-      } else {
-        convert_arg<short>(arg, t);
-      }
-      break;
-    case 'l':
-      if (t == 'l') {
-        ++it;
-        t = it != end ? *it : 0;
-        convert_arg<long long>(arg, t);
-      } else {
-        convert_arg<long>(arg, t);
-      }
-      break;
-    case 'j':
-      convert_arg<intmax_t>(arg, t);
-      break;
-    case 'z':
-      convert_arg<size_t>(arg, t);
-      break;
-    case 't':
-      convert_arg<std::ptrdiff_t>(arg, t);
-      break;
-    case 'L':
-      // printf produces garbage when 'L' is omitted for long double, no
-      // need to do the same.
-      break;
-    default:
-      --it;
-      convert_arg<void>(arg, c);
-    }
-
-    // Parse type.
-    if (it == end) throw_format_error("invalid format string");
-    char type = static_cast<char>(*it++);
-    if (arg.is_integral()) {
-      // Normalize type.
-      switch (type) {
-      case 'i':
-      case 'u':
-        type = 'd';
-        break;
-      case 'c':
-        visit_format_arg(char_converter<basic_printf_context<Char>>(arg), arg);
-        break;
-      }
-    }
-    specs.type = parse_printf_presentation_type(type, arg.type());
-    if (specs.type == presentation_type::none)
-      throw_format_error("invalid format specifier");
-
-    start = it;
-
-    // Format argument.
-    visit_format_arg(printf_arg_formatter<Char>(out, specs, context), arg);
-  }
-  write(out, basic_string_view<Char>(start, to_unsigned(it - start)));
-}
-}  // namespace detail
-
-using printf_context = basic_printf_context<char>;
-using wprintf_context = basic_printf_context<wchar_t>;
-
-using printf_args = basic_format_args<printf_context>;
-using wprintf_args = basic_format_args<wprintf_context>;
-
-/**
-  \rst
-  Constructs an `~fmt::format_arg_store` object that contains references to
-  arguments and can be implicitly converted to `~fmt::printf_args`.
-  \endrst
- */
-template <typename... T>
-inline auto make_printf_args(const T&... args)
-    -> format_arg_store<printf_context, T...> {
-  return {args...};
-}
-
-// DEPRECATED!
-template <typename... T>
-inline auto make_wprintf_args(const T&... args)
-    -> format_arg_store<wprintf_context, T...> {
-  return {args...};
-}
-
-template <typename Char>
-inline auto vsprintf(
-    basic_string_view<Char> fmt,
-    basic_format_args<basic_printf_context<type_identity_t<Char>>> args)
-    -> std::basic_string<Char> {
-  auto buf = basic_memory_buffer<Char>();
-  detail::vprintf(buf, fmt, args);
-  return to_string(buf);
-}
-
-/**
-  \rst
-  Formats arguments and returns the result as a string.
-
-  **Example**::
-
-    std::string message = fmt::sprintf("The answer is %d", 42);
-  \endrst
-*/
-template <typename S, typename... T,
-          typename Char = enable_if_t<detail::is_string<S>::value, char_t<S>>>
-inline auto sprintf(const S& fmt, const T&... args) -> std::basic_string<Char> {
-  return vsprintf(detail::to_string_view(fmt),
-                  fmt::make_format_args<basic_printf_context<Char>>(args...));
-}
-
-template <typename Char>
-inline auto vfprintf(
-    std::FILE* f, basic_string_view<Char> fmt,
-    basic_format_args<basic_printf_context<type_identity_t<Char>>> args)
-    -> int {
-  auto buf = basic_memory_buffer<Char>();
-  detail::vprintf(buf, fmt, args);
-  size_t size = buf.size();
-  return std::fwrite(buf.data(), sizeof(Char), size, f) < size
-             ? -1
-             : static_cast<int>(size);
-}
-
-/**
-  \rst
-  Prints formatted data to the file *f*.
-
-  **Example**::
-
-    fmt::fprintf(stderr, "Don't %s!", "panic");
-  \endrst
- */
-template <typename S, typename... T, typename Char = char_t<S>>
-inline auto fprintf(std::FILE* f, const S& fmt, const T&... args) -> int {
-  return vfprintf(f, detail::to_string_view(fmt),
-                  fmt::make_format_args<basic_printf_context<Char>>(args...));
-}
-
-template <typename Char>
-FMT_DEPRECATED inline auto vprintf(
-    basic_string_view<Char> fmt,
-    basic_format_args<basic_printf_context<type_identity_t<Char>>> args)
-    -> int {
-  return vfprintf(stdout, fmt, args);
-}
-
-/**
-  \rst
-  Prints formatted data to ``stdout``.
-
-  **Example**::
-
-    fmt::printf("Elapsed time: %.2f seconds", 1.23);
-  \endrst
- */
-template <typename... T>
-inline auto printf(string_view fmt, const T&... args) -> int {
-  return vfprintf(stdout, fmt, make_printf_args(args...));
-}
-template <typename... T>
-FMT_DEPRECATED inline auto printf(basic_string_view<wchar_t> fmt,
-                                  const T&... args) -> int {
-  return vfprintf(stdout, fmt, make_wprintf_args(args...));
-}
-
-FMT_END_EXPORT
-FMT_END_NAMESPACE
-
-#endif  // FMT_PRINTF_H_
diff --git a/lib/fmt/include/fmt-vt/ranges.h b/lib/fmt/include/fmt-vt/ranges.h
deleted file mode 100644
index c0b51aeef6..0000000000
--- a/lib/fmt/include/fmt-vt/ranges.h
+++ /dev/null
@@ -1,731 +0,0 @@
-// Formatting library for C++ - range and tuple support
-//
-// Copyright (c) 2012 - present, Victor Zverovich and {fmt} contributors
-// All rights reserved.
-//
-// For the license information refer to format.h.
-
-#ifndef FMT_RANGES_H_
-#define FMT_RANGES_H_
-
-#include <initializer_list>
-#include <tuple>
-#include <type_traits>
-
-#include "format.h"
-
-FMT_BEGIN_NAMESPACE
-
-namespace detail {
-
-template <typename Range, typename OutputIt>
-auto copy(const Range& range, OutputIt out) -> OutputIt {
-  for (auto it = range.begin(), end = range.end(); it != end; ++it)
-    *out++ = *it;
-  return out;
-}
-
-template <typename OutputIt>
-auto copy(const char* str, OutputIt out) -> OutputIt {
-  while (*str) *out++ = *str++;
-  return out;
-}
-
-template <typename OutputIt> auto copy(char ch, OutputIt out) -> OutputIt {
-  *out++ = ch;
-  return out;
-}
-
-template <typename OutputIt> auto copy(wchar_t ch, OutputIt out) -> OutputIt {
-  *out++ = ch;
-  return out;
-}
-
-// Returns true if T has a std::string-like interface, like std::string_view.
-template <typename T> class is_std_string_like {
-  template <typename U>
-  static auto check(U* p)
-      -> decltype((void)p->find('a'), p->length(), (void)p->data(), int());
-  template <typename> static void check(...);
-
- public:
-  static constexpr const bool value =
-      is_string<T>::value ||
-      std::is_convertible<T, std_string_view<char>>::value ||
-      !std::is_void<decltype(check<T>(nullptr))>::value;
-};
-
-template <typename Char>
-struct is_std_string_like<fmt::basic_string_view<Char>> : std::true_type {};
-
-template <typename T> class is_map {
-  template <typename U> static auto check(U*) -> typename U::mapped_type;
-  template <typename> static void check(...);
-
- public:
-#ifdef FMT_FORMAT_MAP_AS_LIST  // DEPRECATED!
-  static constexpr const bool value = false;
-#else
-  static constexpr const bool value =
-      !std::is_void<decltype(check<T>(nullptr))>::value;
-#endif
-};
-
-template <typename T> class is_set {
-  template <typename U> static auto check(U*) -> typename U::key_type;
-  template <typename> static void check(...);
-
- public:
-#ifdef FMT_FORMAT_SET_AS_LIST  // DEPRECATED!
-  static constexpr const bool value = false;
-#else
-  static constexpr const bool value =
-      !std::is_void<decltype(check<T>(nullptr))>::value && !is_map<T>::value;
-#endif
-};
-
-template <typename... Ts> struct conditional_helper {};
-
-template <typename T, typename _ = void> struct is_range_ : std::false_type {};
-
-#if !FMT_MSC_VERSION || FMT_MSC_VERSION > 1800
-
-#  define FMT_DECLTYPE_RETURN(val)  \
-    ->decltype(val) { return val; } \
-    static_assert(                  \
-        true, "")  // This makes it so that a semicolon is required after the
-                   // macro, which helps clang-format handle the formatting.
-
-// C array overload
-template <typename T, std::size_t N>
-auto range_begin(const T (&arr)[N]) -> const T* {
-  return arr;
-}
-template <typename T, std::size_t N>
-auto range_end(const T (&arr)[N]) -> const T* {
-  return arr + N;
-}
-
-template <typename T, typename Enable = void>
-struct has_member_fn_begin_end_t : std::false_type {};
-
-template <typename T>
-struct has_member_fn_begin_end_t<T, void_t<decltype(std::declval<T>().begin()),
-                                           decltype(std::declval<T>().end())>>
-    : std::true_type {};
-
-// Member function overload
-template <typename T>
-auto range_begin(T&& rng) FMT_DECLTYPE_RETURN(static_cast<T&&>(rng).begin());
-template <typename T>
-auto range_end(T&& rng) FMT_DECLTYPE_RETURN(static_cast<T&&>(rng).end());
-
-// ADL overload. Only participates in overload resolution if member functions
-// are not found.
-template <typename T>
-auto range_begin(T&& rng)
-    -> enable_if_t<!has_member_fn_begin_end_t<T&&>::value,
-                   decltype(begin(static_cast<T&&>(rng)))> {
-  return begin(static_cast<T&&>(rng));
-}
-template <typename T>
-auto range_end(T&& rng) -> enable_if_t<!has_member_fn_begin_end_t<T&&>::value,
-                                       decltype(end(static_cast<T&&>(rng)))> {
-  return end(static_cast<T&&>(rng));
-}
-
-template <typename T, typename Enable = void>
-struct has_const_begin_end : std::false_type {};
-template <typename T, typename Enable = void>
-struct has_mutable_begin_end : std::false_type {};
-
-template <typename T>
-struct has_const_begin_end<
-    T,
-    void_t<
-        decltype(detail::range_begin(std::declval<const remove_cvref_t<T>&>())),
-        decltype(detail::range_end(std::declval<const remove_cvref_t<T>&>()))>>
-    : std::true_type {};
-
-template <typename T>
-struct has_mutable_begin_end<
-    T, void_t<decltype(detail::range_begin(std::declval<T>())),
-              decltype(detail::range_end(std::declval<T>())),
-              // the extra int here is because older versions of MSVC don't
-              // SFINAE properly unless there are distinct types
-              int>> : std::true_type {};
-
-template <typename T>
-struct is_range_<T, void>
-    : std::integral_constant<bool, (has_const_begin_end<T>::value ||
-                                    has_mutable_begin_end<T>::value)> {};
-#  undef FMT_DECLTYPE_RETURN
-#endif
-
-// tuple_size and tuple_element check.
-template <typename T> class is_tuple_like_ {
-  template <typename U>
-  static auto check(U* p) -> decltype(std::tuple_size<U>::value, int());
-  template <typename> static void check(...);
-
- public:
-  static constexpr const bool value =
-      !std::is_void<decltype(check<T>(nullptr))>::value;
-};
-
-// Check for integer_sequence
-#if defined(__cpp_lib_integer_sequence) || FMT_MSC_VERSION >= 1900
-template <typename T, T... N>
-using integer_sequence = std::integer_sequence<T, N...>;
-template <size_t... N> using index_sequence = std::index_sequence<N...>;
-template <size_t N> using make_index_sequence = std::make_index_sequence<N>;
-#else
-template <typename T, T... N> struct integer_sequence {
-  using value_type = T;
-
-  static FMT_CONSTEXPR size_t size() { return sizeof...(N); }
-};
-
-template <size_t... N> using index_sequence = integer_sequence<size_t, N...>;
-
-template <typename T, size_t N, T... Ns>
-struct make_integer_sequence : make_integer_sequence<T, N - 1, N - 1, Ns...> {};
-template <typename T, T... Ns>
-struct make_integer_sequence<T, 0, Ns...> : integer_sequence<T, Ns...> {};
-
-template <size_t N>
-using make_index_sequence = make_integer_sequence<size_t, N>;
-#endif
-
-template <typename T>
-using tuple_index_sequence = make_index_sequence<std::tuple_size<T>::value>;
-
-template <typename T, typename C, bool = is_tuple_like_<T>::value>
-class is_tuple_formattable_ {
- public:
-  static constexpr const bool value = false;
-};
-template <typename T, typename C> class is_tuple_formattable_<T, C, true> {
-  template <std::size_t... Is>
-  static std::true_type check2(index_sequence<Is...>,
-                               integer_sequence<bool, (Is == Is)...>);
-  static std::false_type check2(...);
-  template <std::size_t... Is>
-  static decltype(check2(
-      index_sequence<Is...>{},
-      integer_sequence<
-          bool, (is_formattable<typename std::tuple_element<Is, T>::type,
-                                C>::value)...>{})) check(index_sequence<Is...>);
-
- public:
-  static constexpr const bool value =
-      decltype(check(tuple_index_sequence<T>{}))::value;
-};
-
-template <typename Tuple, typename F, size_t... Is>
-FMT_CONSTEXPR void for_each(index_sequence<Is...>, Tuple&& t, F&& f) {
-  using std::get;
-  // Using a free function get<Is>(Tuple) now.
-  const int unused[] = {0, ((void)f(get<Is>(t)), 0)...};
-  ignore_unused(unused);
-}
-
-template <typename Tuple, typename F>
-FMT_CONSTEXPR void for_each(Tuple&& t, F&& f) {
-  for_each(tuple_index_sequence<remove_cvref_t<Tuple>>(),
-           std::forward<Tuple>(t), std::forward<F>(f));
-}
-
-template <typename Tuple1, typename Tuple2, typename F, size_t... Is>
-void for_each2(index_sequence<Is...>, Tuple1&& t1, Tuple2&& t2, F&& f) {
-  using std::get;
-  const int unused[] = {0, ((void)f(get<Is>(t1), get<Is>(t2)), 0)...};
-  ignore_unused(unused);
-}
-
-template <typename Tuple1, typename Tuple2, typename F>
-void for_each2(Tuple1&& t1, Tuple2&& t2, F&& f) {
-  for_each2(tuple_index_sequence<remove_cvref_t<Tuple1>>(),
-            std::forward<Tuple1>(t1), std::forward<Tuple2>(t2),
-            std::forward<F>(f));
-}
-
-namespace tuple {
-// Workaround a bug in MSVC 2019 (v140).
-template <typename Char, typename... T>
-using result_t = std::tuple<formatter<remove_cvref_t<T>, Char>...>;
-
-using std::get;
-template <typename Tuple, typename Char, std::size_t... Is>
-auto get_formatters(index_sequence<Is...>)
-    -> result_t<Char, decltype(get<Is>(std::declval<Tuple>()))...>;
-}  // namespace tuple
-
-#if FMT_MSC_VERSION && FMT_MSC_VERSION < 1920
-// Older MSVC doesn't get the reference type correctly for arrays.
-template <typename R> struct range_reference_type_impl {
-  using type = decltype(*detail::range_begin(std::declval<R&>()));
-};
-
-template <typename T, std::size_t N> struct range_reference_type_impl<T[N]> {
-  using type = T&;
-};
-
-template <typename T>
-using range_reference_type = typename range_reference_type_impl<T>::type;
-#else
-template <typename Range>
-using range_reference_type =
-    decltype(*detail::range_begin(std::declval<Range&>()));
-#endif
-
-// We don't use the Range's value_type for anything, but we do need the Range's
-// reference type, with cv-ref stripped.
-template <typename Range>
-using uncvref_type = remove_cvref_t<range_reference_type<Range>>;
-
-template <typename Formatter>
-FMT_CONSTEXPR auto maybe_set_debug_format(Formatter& f, bool set)
-    -> decltype(f.set_debug_format(set)) {
-  f.set_debug_format(set);
-}
-template <typename Formatter>
-FMT_CONSTEXPR void maybe_set_debug_format(Formatter&, ...) {}
-
-// These are not generic lambdas for compatibility with C++11.
-template <typename ParseContext> struct parse_empty_specs {
-  template <typename Formatter> FMT_CONSTEXPR void operator()(Formatter& f) {
-    f.parse(ctx);
-    detail::maybe_set_debug_format(f, true);
-  }
-  ParseContext& ctx;
-};
-template <typename FormatContext> struct format_tuple_element {
-  using char_type = typename FormatContext::char_type;
-
-  template <typename T>
-  void operator()(const formatter<T, char_type>& f, const T& v) {
-    if (i > 0)
-      ctx.advance_to(detail::copy_str<char_type>(separator, ctx.out()));
-    ctx.advance_to(f.format(v, ctx));
-    ++i;
-  }
-
-  int i;
-  FormatContext& ctx;
-  basic_string_view<char_type> separator;
-};
-
-}  // namespace detail
-
-template <typename T> struct is_tuple_like {
-  static constexpr const bool value =
-      detail::is_tuple_like_<T>::value && !detail::is_range_<T>::value;
-};
-
-template <typename T, typename C> struct is_tuple_formattable {
-  static constexpr const bool value =
-      detail::is_tuple_formattable_<T, C>::value;
-};
-
-template <typename Tuple, typename Char>
-struct formatter<Tuple, Char,
-                 enable_if_t<fmt::is_tuple_like<Tuple>::value &&
-                             fmt::is_tuple_formattable<Tuple, Char>::value>> {
- private:
-  decltype(detail::tuple::get_formatters<Tuple, Char>(
-      detail::tuple_index_sequence<Tuple>())) formatters_;
-
-  basic_string_view<Char> separator_ = detail::string_literal<Char, ',', ' '>{};
-  basic_string_view<Char> opening_bracket_ =
-      detail::string_literal<Char, '('>{};
-  basic_string_view<Char> closing_bracket_ =
-      detail::string_literal<Char, ')'>{};
-
- public:
-  FMT_CONSTEXPR formatter() {}
-
-  FMT_CONSTEXPR void set_separator(basic_string_view<Char> sep) {
-    separator_ = sep;
-  }
-
-  FMT_CONSTEXPR void set_brackets(basic_string_view<Char> open,
-                                  basic_string_view<Char> close) {
-    opening_bracket_ = open;
-    closing_bracket_ = close;
-  }
-
-  template <typename ParseContext>
-  FMT_CONSTEXPR auto parse(ParseContext& ctx) -> decltype(ctx.begin()) {
-    auto it = ctx.begin();
-    if (it != ctx.end() && *it != '}')
-      FMT_THROW(format_error("invalid format specifier"));
-    detail::for_each(formatters_, detail::parse_empty_specs<ParseContext>{ctx});
-    return it;
-  }
-
-  template <typename FormatContext>
-  auto format(const Tuple& value, FormatContext& ctx) const
-      -> decltype(ctx.out()) {
-    ctx.advance_to(detail::copy_str<Char>(opening_bracket_, ctx.out()));
-    detail::for_each2(
-        formatters_, value,
-        detail::format_tuple_element<FormatContext>{0, ctx, separator_});
-    return detail::copy_str<Char>(closing_bracket_, ctx.out());
-  }
-};
-
-template <typename T, typename Char> struct is_range {
-  static constexpr const bool value =
-      detail::is_range_<T>::value && !detail::is_std_string_like<T>::value &&
-      !std::is_convertible<T, std::basic_string<Char>>::value &&
-      !std::is_convertible<T, detail::std_string_view<Char>>::value;
-};
-
-namespace detail {
-template <typename Context> struct range_mapper {
-  using mapper = arg_mapper<Context>;
-
-  template <typename T,
-            FMT_ENABLE_IF(has_formatter<remove_cvref_t<T>, Context>::value)>
-  static auto map(T&& value) -> T&& {
-    return static_cast<T&&>(value);
-  }
-  template <typename T,
-            FMT_ENABLE_IF(!has_formatter<remove_cvref_t<T>, Context>::value)>
-  static auto map(T&& value)
-      -> decltype(mapper().map(static_cast<T&&>(value))) {
-    return mapper().map(static_cast<T&&>(value));
-  }
-};
-
-template <typename Char, typename Element>
-using range_formatter_type =
-    formatter<remove_cvref_t<decltype(range_mapper<buffer_context<Char>>{}.map(
-                  std::declval<Element>()))>,
-              Char>;
-
-template <typename R>
-using maybe_const_range =
-    conditional_t<has_const_begin_end<R>::value, const R, R>;
-
-// Workaround a bug in MSVC 2015 and earlier.
-#if !FMT_MSC_VERSION || FMT_MSC_VERSION >= 1910
-template <typename R, typename Char>
-struct is_formattable_delayed
-    : is_formattable<uncvref_type<maybe_const_range<R>>, Char> {};
-#endif
-}  // namespace detail
-
-template <typename T, typename Char, typename Enable = void>
-struct range_formatter;
-
-template <typename T, typename Char>
-struct range_formatter<
-    T, Char,
-    enable_if_t<conjunction<std::is_same<T, remove_cvref_t<T>>,
-                            is_formattable<T, Char>>::value>> {
- private:
-  detail::range_formatter_type<Char, T> underlying_;
-  basic_string_view<Char> separator_ = detail::string_literal<Char, ',', ' '>{};
-  basic_string_view<Char> opening_bracket_ =
-      detail::string_literal<Char, '['>{};
-  basic_string_view<Char> closing_bracket_ =
-      detail::string_literal<Char, ']'>{};
-
- public:
-  FMT_CONSTEXPR range_formatter() {}
-
-  FMT_CONSTEXPR auto underlying() -> detail::range_formatter_type<Char, T>& {
-    return underlying_;
-  }
-
-  FMT_CONSTEXPR void set_separator(basic_string_view<Char> sep) {
-    separator_ = sep;
-  }
-
-  FMT_CONSTEXPR void set_brackets(basic_string_view<Char> open,
-                                  basic_string_view<Char> close) {
-    opening_bracket_ = open;
-    closing_bracket_ = close;
-  }
-
-  template <typename ParseContext>
-  FMT_CONSTEXPR auto parse(ParseContext& ctx) -> decltype(ctx.begin()) {
-    auto it = ctx.begin();
-    auto end = ctx.end();
-
-    if (it != end && *it == 'n') {
-      set_brackets({}, {});
-      ++it;
-    }
-
-    if (it != end && *it != '}') {
-      if (*it != ':') FMT_THROW(format_error("invalid format specifier"));
-      ++it;
-    } else {
-      detail::maybe_set_debug_format(underlying_, true);
-    }
-
-    ctx.advance_to(it);
-    return underlying_.parse(ctx);
-  }
-
-  template <typename R, typename FormatContext>
-  auto format(R&& range, FormatContext& ctx) const -> decltype(ctx.out()) {
-    detail::range_mapper<buffer_context<Char>> mapper;
-    auto out = ctx.out();
-    out = detail::copy_str<Char>(opening_bracket_, out);
-    int i = 0;
-    auto it = detail::range_begin(range);
-    auto end = detail::range_end(range);
-    for (; it != end; ++it) {
-      if (i > 0) out = detail::copy_str<Char>(separator_, out);
-      ctx.advance_to(out);
-      out = underlying_.format(mapper.map(*it), ctx);
-      ++i;
-    }
-    out = detail::copy_str<Char>(closing_bracket_, out);
-    return out;
-  }
-};
-
-enum class range_format { disabled, map, set, sequence, string, debug_string };
-
-namespace detail {
-template <typename T>
-struct range_format_kind_
-    : std::integral_constant<range_format,
-                             std::is_same<uncvref_type<T>, T>::value
-                                 ? range_format::disabled
-                             : is_map<T>::value ? range_format::map
-                             : is_set<T>::value ? range_format::set
-                                                : range_format::sequence> {};
-
-template <range_format K, typename R, typename Char, typename Enable = void>
-struct range_default_formatter;
-
-template <range_format K>
-using range_format_constant = std::integral_constant<range_format, K>;
-
-template <range_format K, typename R, typename Char>
-struct range_default_formatter<
-    K, R, Char,
-    enable_if_t<(K == range_format::sequence || K == range_format::map ||
-                 K == range_format::set)>> {
-  using range_type = detail::maybe_const_range<R>;
-  range_formatter<detail::uncvref_type<range_type>, Char> underlying_;
-
-  FMT_CONSTEXPR range_default_formatter() { init(range_format_constant<K>()); }
-
-  FMT_CONSTEXPR void init(range_format_constant<range_format::set>) {
-    underlying_.set_brackets(detail::string_literal<Char, '{'>{},
-                             detail::string_literal<Char, '}'>{});
-  }
-
-  FMT_CONSTEXPR void init(range_format_constant<range_format::map>) {
-    underlying_.set_brackets(detail::string_literal<Char, '{'>{},
-                             detail::string_literal<Char, '}'>{});
-    underlying_.underlying().set_brackets({}, {});
-    underlying_.underlying().set_separator(
-        detail::string_literal<Char, ':', ' '>{});
-  }
-
-  FMT_CONSTEXPR void init(range_format_constant<range_format::sequence>) {}
-
-  template <typename ParseContext>
-  FMT_CONSTEXPR auto parse(ParseContext& ctx) -> decltype(ctx.begin()) {
-    return underlying_.parse(ctx);
-  }
-
-  template <typename FormatContext>
-  auto format(range_type& range, FormatContext& ctx) const
-      -> decltype(ctx.out()) {
-    return underlying_.format(range, ctx);
-  }
-};
-}  // namespace detail
-
-template <typename T, typename Char, typename Enable = void>
-struct range_format_kind
-    : conditional_t<
-          is_range<T, Char>::value, detail::range_format_kind_<T>,
-          std::integral_constant<range_format, range_format::disabled>> {};
-
-template <typename R, typename Char>
-struct formatter<
-    R, Char,
-    enable_if_t<conjunction<bool_constant<range_format_kind<R, Char>::value !=
-                                          range_format::disabled>
-// Workaround a bug in MSVC 2015 and earlier.
-#if !FMT_MSC_VERSION || FMT_MSC_VERSION >= 1910
-                            ,
-                            detail::is_formattable_delayed<R, Char>
-#endif
-                            >::value>>
-    : detail::range_default_formatter<range_format_kind<R, Char>::value, R,
-                                      Char> {
-};
-
-template <typename Char, typename... T> struct tuple_join_view : detail::view {
-  const std::tuple<T...>& tuple;
-  basic_string_view<Char> sep;
-
-  tuple_join_view(const std::tuple<T...>& t, basic_string_view<Char> s)
-      : tuple(t), sep{s} {}
-};
-
-// Define FMT_TUPLE_JOIN_SPECIFIERS to enable experimental format specifiers
-// support in tuple_join. It is disabled by default because of issues with
-// the dynamic width and precision.
-#ifndef FMT_TUPLE_JOIN_SPECIFIERS
-#  define FMT_TUPLE_JOIN_SPECIFIERS 0
-#endif
-
-template <typename Char, typename... T>
-struct formatter<tuple_join_view<Char, T...>, Char> {
-  template <typename ParseContext>
-  FMT_CONSTEXPR auto parse(ParseContext& ctx) -> decltype(ctx.begin()) {
-    return do_parse(ctx, std::integral_constant<size_t, sizeof...(T)>());
-  }
-
-  template <typename FormatContext>
-  auto format(const tuple_join_view<Char, T...>& value,
-              FormatContext& ctx) const -> typename FormatContext::iterator {
-    return do_format(value, ctx,
-                     std::integral_constant<size_t, sizeof...(T)>());
-  }
-
- private:
-  std::tuple<formatter<typename std::decay<T>::type, Char>...> formatters_;
-
-  template <typename ParseContext>
-  FMT_CONSTEXPR auto do_parse(ParseContext& ctx,
-                              std::integral_constant<size_t, 0>)
-      -> decltype(ctx.begin()) {
-    return ctx.begin();
-  }
-
-  template <typename ParseContext, size_t N>
-  FMT_CONSTEXPR auto do_parse(ParseContext& ctx,
-                              std::integral_constant<size_t, N>)
-      -> decltype(ctx.begin()) {
-    auto end = ctx.begin();
-#if FMT_TUPLE_JOIN_SPECIFIERS
-    end = std::get<sizeof...(T) - N>(formatters_).parse(ctx);
-    if (N > 1) {
-      auto end1 = do_parse(ctx, std::integral_constant<size_t, N - 1>());
-      if (end != end1)
-        FMT_THROW(format_error("incompatible format specs for tuple elements"));
-    }
-#endif
-    return end;
-  }
-
-  template <typename FormatContext>
-  auto do_format(const tuple_join_view<Char, T...>&, FormatContext& ctx,
-                 std::integral_constant<size_t, 0>) const ->
-      typename FormatContext::iterator {
-    return ctx.out();
-  }
-
-  template <typename FormatContext, size_t N>
-  auto do_format(const tuple_join_view<Char, T...>& value, FormatContext& ctx,
-                 std::integral_constant<size_t, N>) const ->
-      typename FormatContext::iterator {
-    auto out = std::get<sizeof...(T) - N>(formatters_)
-                   .format(std::get<sizeof...(T) - N>(value.tuple), ctx);
-    if (N > 1) {
-      out = std::copy(value.sep.begin(), value.sep.end(), out);
-      ctx.advance_to(out);
-      return do_format(value, ctx, std::integral_constant<size_t, N - 1>());
-    }
-    return out;
-  }
-};
-
-namespace detail {
-// Check if T has an interface like a container adaptor (e.g. std::stack,
-// std::queue, std::priority_queue).
-template <typename T> class is_container_adaptor_like {
-  template <typename U> static auto check(U* p) -> typename U::container_type;
-  template <typename> static void check(...);
-
- public:
-  static constexpr const bool value =
-      !std::is_void<decltype(check<T>(nullptr))>::value;
-};
-
-template <typename Container> struct all {
-  const Container& c;
-  auto begin() const -> typename Container::const_iterator { return c.begin(); }
-  auto end() const -> typename Container::const_iterator { return c.end(); }
-};
-}  // namespace detail
-
-template <typename T, typename Char>
-struct formatter<
-    T, Char,
-    enable_if_t<conjunction<detail::is_container_adaptor_like<T>,
-                            bool_constant<range_format_kind<T, Char>::value ==
-                                          range_format::disabled>>::value>>
-    : formatter<detail::all<typename T::container_type>, Char> {
-  using all = detail::all<typename T::container_type>;
-  template <typename FormatContext>
-  auto format(const T& t, FormatContext& ctx) const -> decltype(ctx.out()) {
-    struct getter : T {
-      static auto get(const T& t) -> all {
-        return {t.*(&getter::c)};  // Access c through the derived class.
-      }
-    };
-    return formatter<all>::format(getter::get(t), ctx);
-  }
-};
-
-FMT_BEGIN_EXPORT
-
-/**
-  \rst
-  Returns an object that formats `tuple` with elements separated by `sep`.
-
-  **Example**::
-
-    std::tuple<int, char> t = {1, 'a'};
-    fmt::print("{}", fmt::join(t, ", "));
-    // Output: "1, a"
-  \endrst
- */
-template <typename... T>
-FMT_CONSTEXPR auto join(const std::tuple<T...>& tuple, string_view sep)
-    -> tuple_join_view<char, T...> {
-  return {tuple, sep};
-}
-
-template <typename... T>
-FMT_CONSTEXPR auto join(const std::tuple<T...>& tuple,
-                        basic_string_view<wchar_t> sep)
-    -> tuple_join_view<wchar_t, T...> {
-  return {tuple, sep};
-}
-
-/**
-  \rst
-  Returns an object that formats `initializer_list` with elements separated by
-  `sep`.
-
-  **Example**::
-
-    fmt::print("{}", fmt::join({1, 2, 3}, ", "));
-    // Output: "1, 2, 3"
-  \endrst
- */
-template <typename T>
-auto join(std::initializer_list<T> list, string_view sep)
-    -> join_view<const T*, const T*> {
-  return join(std::begin(list), std::end(list), sep);
-}
-
-FMT_END_EXPORT
-FMT_END_NAMESPACE
-
-#endif  // FMT_RANGES_H_
diff --git a/lib/fmt/include/fmt-vt/std.h b/lib/fmt/include/fmt-vt/std.h
deleted file mode 100644
index 4799df1a31..0000000000
--- a/lib/fmt/include/fmt-vt/std.h
+++ /dev/null
@@ -1,498 +0,0 @@
-// Formatting library for C++ - formatters for standard library types
-//
-// Copyright (c) 2012 - present, Victor Zverovich
-// All rights reserved.
-//
-// For the license information refer to format.h.
-
-#ifndef FMT_STD_H_
-#define FMT_STD_H_
-
-#include <atomic>
-#include <bitset>
-#include <cstdlib>
-#include <exception>
-#include <memory>
-#include <thread>
-#include <type_traits>
-#include <typeinfo>
-#include <utility>
-#include <vector>
-
-#include "format.h"
-#include "ostream.h"
-
-#if FMT_HAS_INCLUDE(<version>)
-#  include <version>
-#endif
-// Checking FMT_CPLUSPLUS for warning suppression in MSVC.
-#if FMT_CPLUSPLUS >= 201703L
-#  if FMT_HAS_INCLUDE(<filesystem>)
-#    include <filesystem>
-#  endif
-#  if FMT_HAS_INCLUDE(<variant>)
-#    include <variant>
-#  endif
-#  if FMT_HAS_INCLUDE(<optional>)
-#    include <optional>
-#  endif
-#endif
-
-// GCC 4 does not support FMT_HAS_INCLUDE.
-#if FMT_HAS_INCLUDE(<cxxabi.h>) || defined(__GLIBCXX__)
-#  include <cxxabi.h>
-// Android NDK with gabi++ library on some architectures does not implement
-// abi::__cxa_demangle().
-#  ifndef __GABIXX_CXXABI_H__
-#    define FMT_HAS_ABI_CXA_DEMANGLE
-#  endif
-#endif
-
-// Check if typeid is available.
-#ifndef FMT_USE_TYPEID
-// __RTTI is for EDG compilers. In MSVC typeid is available without RTTI.
-#  if defined(__GXX_RTTI) || FMT_HAS_FEATURE(cxx_rtti) || FMT_MSC_VERSION || \
-      defined(__INTEL_RTTI__) || defined(__RTTI)
-#    define FMT_USE_TYPEID 1
-#  else
-#    define FMT_USE_TYPEID 0
-#  endif
-#endif
-
-// For older Xcode versions, __cpp_lib_xxx flags are inaccurately defined.
-#ifndef FMT_CPP_LIB_FILESYSTEM
-#  ifdef __cpp_lib_filesystem
-#    define FMT_CPP_LIB_FILESYSTEM __cpp_lib_filesystem
-#  else
-#    define FMT_CPP_LIB_FILESYSTEM 0
-# endif
-#endif
-
-#ifndef FMT_CPP_LIB_VARIANT
-#  ifdef __cpp_lib_variant
-#    define FMT_CPP_LIB_VARIANT __cpp_lib_variant
-#  else
-#    define FMT_CPP_LIB_VARIANT 0
-#  endif
-#endif
-
-#if FMT_CPP_LIB_FILESYSTEM
-FMT_BEGIN_NAMESPACE
-
-namespace detail {
-
-template <typename Char, typename PathChar> auto get_path_string(
-  const std::filesystem::path& p, const std::basic_string<PathChar>& native) {
-  if constexpr (std::is_same_v<Char, char> && std::is_same_v<PathChar, wchar_t>)
-    return to_utf8<wchar_t>(native, to_utf8_error_policy::replace);
-  else
-    return p.string<Char>();
-}
-
-template <typename Char, typename PathChar>
-void write_escaped_path(basic_memory_buffer<Char>& quoted,
-                        const std::filesystem::path& p,
-                        const std::basic_string<PathChar>& native) {
-  if constexpr (std::is_same_v<Char, char> && std::is_same_v<PathChar, wchar_t>) {
-    auto buf = basic_memory_buffer<wchar_t>();
-    write_escaped_string<wchar_t>(std::back_inserter(buf), native);
-    bool valid = to_utf8<wchar_t>::convert(quoted, {buf.data(), buf.size()});
-    FMT_ASSERT(valid, "invalid utf16");
-  } else if constexpr (std::is_same_v<Char, PathChar>) {
-    write_escaped_string<std::filesystem::path::value_type>(
-        std::back_inserter(quoted), native);
-  } else {
-    write_escaped_string<Char>(std::back_inserter(quoted), p.string<Char>());
-  }
-}
-
-}  // namespace detail
-
-FMT_EXPORT
-template <typename Char> struct formatter<std::filesystem::path, Char> {
- private:
-  format_specs<Char> specs_;
-  detail::arg_ref<Char> width_ref_;
-  bool debug_ = false;
-
- public:
-  FMT_CONSTEXPR void set_debug_format(bool set = true) { debug_ = set; }
-
-  template <typename ParseContext> FMT_CONSTEXPR auto parse(ParseContext& ctx) {
-    auto it = ctx.begin(), end = ctx.end();
-    if (it == end) return it;
-
-    it = detail::parse_align(it, end, specs_);
-    if (it == end) return it;
-
-    it = detail::parse_dynamic_spec(it, end, specs_.width, width_ref_, ctx);
-    if (it != end && *it == '?') {
-      debug_ = true;
-      ++it;
-    }
-    return it;
-  }
-
-  template <typename FormatContext>
-  auto format(const std::filesystem::path& p, FormatContext& ctx) const {
-    auto specs = specs_;
-    detail::handle_dynamic_spec<detail::width_checker>(specs.width, width_ref_,
-                                                       ctx);
-    if (!debug_) {
-      auto s = detail::get_path_string<Char>(p, p.native());
-      return detail::write(ctx.out(), basic_string_view<Char>(s), specs);
-    }
-    auto quoted = basic_memory_buffer<Char>();
-    detail::write_escaped_path(quoted, p, p.native());
-    return detail::write(ctx.out(),
-                         basic_string_view<Char>(quoted.data(), quoted.size()),
-                         specs);
-  }
-};
-FMT_END_NAMESPACE
-#endif // FMT_CPP_LIB_FILESYSTEM
-
-FMT_BEGIN_NAMESPACE
-FMT_EXPORT
-template <std::size_t N, typename Char>
-struct formatter<std::bitset<N>, Char> : nested_formatter<string_view> {
- private:
-  // Functor because C++11 doesn't support generic lambdas.
-  struct writer {
-    const std::bitset<N>& bs;
-
-    template <typename OutputIt>
-    FMT_CONSTEXPR OutputIt operator()(OutputIt out) {
-      for (auto pos = N; pos > 0; --pos) {
-        out = detail::write<Char>(out, bs[pos - 1] ? Char('1') : Char('0'));
-      }
-
-      return out;
-    }
-  };
-
- public:
-  template <typename FormatContext>
-  auto format(const std::bitset<N>& bs, FormatContext& ctx) const
-      -> decltype(ctx.out()) {
-    return write_padded(ctx, writer{bs});
-  }
-};
-
-FMT_EXPORT
-template <typename Char>
-struct formatter<std::thread::id, Char> : basic_ostream_formatter<Char> {};
-FMT_END_NAMESPACE
-
-#ifdef __cpp_lib_optional
-FMT_BEGIN_NAMESPACE
-FMT_EXPORT
-template <typename T, typename Char>
-struct formatter<std::optional<T>, Char,
-                 std::enable_if_t<is_formattable<T, Char>::value>> {
- private:
-  formatter<T, Char> underlying_;
-  static constexpr basic_string_view<Char> optional =
-      detail::string_literal<Char, 'o', 'p', 't', 'i', 'o', 'n', 'a', 'l',
-                             '('>{};
-  static constexpr basic_string_view<Char> none =
-      detail::string_literal<Char, 'n', 'o', 'n', 'e'>{};
-
-  template <class U>
-  FMT_CONSTEXPR static auto maybe_set_debug_format(U& u, bool set)
-      -> decltype(u.set_debug_format(set)) {
-    u.set_debug_format(set);
-  }
-
-  template <class U>
-  FMT_CONSTEXPR static void maybe_set_debug_format(U&, ...) {}
-
- public:
-  template <typename ParseContext> FMT_CONSTEXPR auto parse(ParseContext& ctx) {
-    maybe_set_debug_format(underlying_, true);
-    return underlying_.parse(ctx);
-  }
-
-  template <typename FormatContext>
-  auto format(std::optional<T> const& opt, FormatContext& ctx) const
-      -> decltype(ctx.out()) {
-    if (!opt) return detail::write<Char>(ctx.out(), none);
-
-    auto out = ctx.out();
-    out = detail::write<Char>(out, optional);
-    ctx.advance_to(out);
-    out = underlying_.format(*opt, ctx);
-    return detail::write(out, ')');
-  }
-};
-FMT_END_NAMESPACE
-#endif  // __cpp_lib_optional
-
-#if FMT_CPP_LIB_VARIANT
-FMT_BEGIN_NAMESPACE
-namespace detail {
-
-template <typename T>
-using variant_index_sequence =
-    std::make_index_sequence<std::variant_size<T>::value>;
-
-template <typename> struct is_variant_like_ : std::false_type {};
-template <typename... Types>
-struct is_variant_like_<std::variant<Types...>> : std::true_type {};
-
-// formattable element check.
-template <typename T, typename C> class is_variant_formattable_ {
-  template <std::size_t... Is>
-  static std::conjunction<
-      is_formattable<std::variant_alternative_t<Is, T>, C>...>
-      check(std::index_sequence<Is...>);
-
- public:
-  static constexpr const bool value =
-      decltype(check(variant_index_sequence<T>{}))::value;
-};
-
-template <typename Char, typename OutputIt, typename T>
-auto write_variant_alternative(OutputIt out, const T& v) -> OutputIt {
-  if constexpr (is_string<T>::value)
-    return write_escaped_string<Char>(out, detail::to_string_view(v));
-  else if constexpr (std::is_same_v<T, Char>)
-    return write_escaped_char(out, v);
-  else
-    return write<Char>(out, v);
-}
-
-}  // namespace detail
-
-template <typename T> struct is_variant_like {
-  static constexpr const bool value = detail::is_variant_like_<T>::value;
-};
-
-template <typename T, typename C> struct is_variant_formattable {
-  static constexpr const bool value =
-      detail::is_variant_formattable_<T, C>::value;
-};
-
-FMT_EXPORT
-template <typename Char> struct formatter<std::monostate, Char> {
-  template <typename ParseContext>
-  FMT_CONSTEXPR auto parse(ParseContext& ctx) -> decltype(ctx.begin()) {
-    return ctx.begin();
-  }
-
-  template <typename FormatContext>
-  auto format(const std::monostate&, FormatContext& ctx) const
-      -> decltype(ctx.out()) {
-    return detail::write<Char>(ctx.out(), "monostate");
-  }
-};
-
-FMT_EXPORT
-template <typename Variant, typename Char>
-struct formatter<
-    Variant, Char,
-    std::enable_if_t<std::conjunction_v<
-        is_variant_like<Variant>, is_variant_formattable<Variant, Char>>>> {
-  template <typename ParseContext>
-  FMT_CONSTEXPR auto parse(ParseContext& ctx) -> decltype(ctx.begin()) {
-    return ctx.begin();
-  }
-
-  template <typename FormatContext>
-  auto format(const Variant& value, FormatContext& ctx) const
-      -> decltype(ctx.out()) {
-    auto out = ctx.out();
-
-    out = detail::write<Char>(out, "variant(");
-    FMT_TRY {
-      std::visit(
-          [&](const auto& v) {
-            out = detail::write_variant_alternative<Char>(out, v);
-          },
-          value);
-    }
-    FMT_CATCH(const std::bad_variant_access&) {
-      detail::write<Char>(out, "valueless by exception");
-    }
-    *out++ = ')';
-    return out;
-  }
-};
-FMT_END_NAMESPACE
-#endif  // FMT_CPP_LIB_VARIANT
-
-FMT_BEGIN_NAMESPACE
-FMT_EXPORT
-template <typename Char> struct formatter<std::error_code, Char> {
-  template <typename ParseContext>
-  FMT_CONSTEXPR auto parse(ParseContext& ctx) -> decltype(ctx.begin()) {
-    return ctx.begin();
-  }
-
-  template <typename FormatContext>
-  FMT_CONSTEXPR auto format(const std::error_code& ec, FormatContext& ctx) const
-      -> decltype(ctx.out()) {
-    auto out = ctx.out();
-    out = detail::write_bytes(out, ec.category().name(), format_specs<Char>());
-    out = detail::write<Char>(out, Char(':'));
-    out = detail::write<Char>(out, ec.value());
-    return out;
-  }
-};
-
-FMT_EXPORT
-template <typename T, typename Char>
-struct formatter<
-    T, Char,
-    typename std::enable_if<std::is_base_of<std::exception, T>::value>::type> {
- private:
-  bool with_typename_ = false;
-
- public:
-  FMT_CONSTEXPR auto parse(basic_format_parse_context<Char>& ctx)
-      -> decltype(ctx.begin()) {
-    auto it = ctx.begin();
-    auto end = ctx.end();
-    if (it == end || *it == '}') return it;
-    if (*it == 't') {
-      ++it;
-      with_typename_ = FMT_USE_TYPEID != 0;
-    }
-    return it;
-  }
-
-  template <typename OutputIt>
-  auto format(const std::exception& ex,
-              basic_format_context<OutputIt, Char>& ctx) const -> OutputIt {
-    format_specs<Char> spec;
-    auto out = ctx.out();
-    if (!with_typename_)
-      return detail::write_bytes(out, string_view(ex.what()), spec);
-
-#if FMT_USE_TYPEID
-    const std::type_info& ti = typeid(ex);
-#  ifdef FMT_HAS_ABI_CXA_DEMANGLE
-    int status = 0;
-    std::size_t size = 0;
-    std::unique_ptr<char, decltype(&std::free)> demangled_name_ptr(
-        abi::__cxa_demangle(ti.name(), nullptr, &size, &status), &std::free);
-
-    string_view demangled_name_view;
-    if (demangled_name_ptr) {
-      demangled_name_view = demangled_name_ptr.get();
-
-      // Normalization of stdlib inline namespace names.
-      // libc++ inline namespaces.
-      //  std::__1::*       -> std::*
-      //  std::__1::__fs::* -> std::*
-      // libstdc++ inline namespaces.
-      //  std::__cxx11::*             -> std::*
-      //  std::filesystem::__cxx11::* -> std::filesystem::*
-      if (demangled_name_view.starts_with("std::")) {
-        char* begin = demangled_name_ptr.get();
-        char* to = begin + 5;  // std::
-        for (char *from = to, *end = begin + demangled_name_view.size();
-             from < end;) {
-          // This is safe, because demangled_name is NUL-terminated.
-          if (from[0] == '_' && from[1] == '_') {
-            char* next = from + 1;
-            while (next < end && *next != ':') next++;
-            if (next[0] == ':' && next[1] == ':') {
-              from = next + 2;
-              continue;
-            }
-          }
-          *to++ = *from++;
-        }
-        demangled_name_view = {begin, detail::to_unsigned(to - begin)};
-      }
-    } else {
-      demangled_name_view = string_view(ti.name());
-    }
-    out = detail::write_bytes(out, demangled_name_view, spec);
-#  elif FMT_MSC_VERSION
-    string_view demangled_name_view(ti.name());
-    if (demangled_name_view.starts_with("class "))
-      demangled_name_view.remove_prefix(6);
-    else if (demangled_name_view.starts_with("struct "))
-      demangled_name_view.remove_prefix(7);
-    out = detail::write_bytes(out, demangled_name_view, spec);
-#  else
-    out = detail::write_bytes(out, string_view(ti.name()), spec);
-#  endif
-    *out++ = ':';
-    *out++ = ' ';
-    return detail::write_bytes(out, string_view(ex.what()), spec);
-#endif
-  }
-};
-
-namespace detail {
-
-template <typename T, typename Enable = void>
-struct has_flip : std::false_type {};
-
-template <typename T>
-struct has_flip<T, void_t<decltype(std::declval<T>().flip())>>
-    : std::true_type {};
-
-template <typename T> struct is_bit_reference_like {
-  static constexpr const bool value =
-      std::is_convertible<T, bool>::value &&
-      std::is_nothrow_assignable<T, bool>::value && has_flip<T>::value;
-};
-
-#ifdef _LIBCPP_VERSION
-
-// Workaround for libc++ incompatibility with C++ standard.
-// According to the Standard, `bitset::operator[] const` returns bool.
-template <typename C>
-struct is_bit_reference_like<std::__bit_const_reference<C>> {
-  static constexpr const bool value = true;
-};
-
-#endif
-
-}  // namespace detail
-
-// We can't use std::vector<bool, Allocator>::reference and
-// std::bitset<N>::reference because the compiler can't deduce Allocator and N
-// in partial specialization.
-FMT_EXPORT
-template <typename BitRef, typename Char>
-struct formatter<BitRef, Char,
-                 enable_if_t<detail::is_bit_reference_like<BitRef>::value>>
-    : formatter<bool, Char> {
-  template <typename FormatContext>
-  FMT_CONSTEXPR auto format(const BitRef& v, FormatContext& ctx) const
-      -> decltype(ctx.out()) {
-    return formatter<bool, Char>::format(v, ctx);
-  }
-};
-
-FMT_EXPORT
-template <typename T, typename Char>
-struct formatter<std::atomic<T>, Char,
-                 enable_if_t<is_formattable<T, Char>::value>>
-    : formatter<T, Char> {
-  template <typename FormatContext>
-  auto format(const std::atomic<T>& v, FormatContext& ctx) const
-      -> decltype(ctx.out()) {
-    return formatter<T, Char>::format(v.load(), ctx);
-  }
-};
-
-#ifdef __cpp_lib_atomic_flag_test
-FMT_EXPORT
-template <typename Char>
-struct formatter<std::atomic_flag, Char> : formatter<bool, Char> {
-  template <typename FormatContext>
-  auto format(const std::atomic_flag& v, FormatContext& ctx) const
-      -> decltype(ctx.out()) {
-    return formatter<bool, Char>::format(v.test(), ctx);
-  }
-};
-#endif  // __cpp_lib_atomic_flag_test
-
-FMT_END_NAMESPACE
-#endif  // FMT_STD_H_
diff --git a/lib/fmt/include/fmt-vt/xchar.h b/lib/fmt/include/fmt-vt/xchar.h
deleted file mode 100644
index 625ec36922..0000000000
--- a/lib/fmt/include/fmt-vt/xchar.h
+++ /dev/null
@@ -1,258 +0,0 @@
-// Formatting library for C++ - optional wchar_t and exotic character support
-//
-// Copyright (c) 2012 - present, Victor Zverovich
-// All rights reserved.
-//
-// For the license information refer to format.h.
-
-#ifndef FMT_XCHAR_H_
-#define FMT_XCHAR_H_
-
-#include <cwchar>
-
-#include "format.h"
-
-#ifndef FMT_STATIC_THOUSANDS_SEPARATOR
-#  include <locale>
-#endif
-
-FMT_BEGIN_NAMESPACE
-namespace detail {
-
-template <typename T>
-using is_exotic_char = bool_constant<!std::is_same<T, char>::value>;
-
-inline auto write_loc(std::back_insert_iterator<detail::buffer<wchar_t>> out,
-                      loc_value value, const format_specs<wchar_t>& specs,
-                      locale_ref loc) -> bool {
-#ifndef FMT_STATIC_THOUSANDS_SEPARATOR
-  auto& numpunct =
-      std::use_facet<std::numpunct<wchar_t>>(loc.get<std::locale>());
-  auto separator = std::wstring();
-  auto grouping = numpunct.grouping();
-  if (!grouping.empty()) separator = std::wstring(1, numpunct.thousands_sep());
-  return value.visit(loc_writer<wchar_t>{out, specs, separator, grouping, {}});
-#endif
-  return false;
-}
-}  // namespace detail
-
-FMT_BEGIN_EXPORT
-
-using wstring_view = basic_string_view<wchar_t>;
-using wformat_parse_context = basic_format_parse_context<wchar_t>;
-using wformat_context = buffer_context<wchar_t>;
-using wformat_args = basic_format_args<wformat_context>;
-using wmemory_buffer = basic_memory_buffer<wchar_t>;
-
-#if FMT_GCC_VERSION && FMT_GCC_VERSION < 409
-// Workaround broken conversion on older gcc.
-template <typename... Args> using wformat_string = wstring_view;
-inline auto runtime(wstring_view s) -> wstring_view { return s; }
-#else
-template <typename... Args>
-using wformat_string = basic_format_string<wchar_t, type_identity_t<Args>...>;
-inline auto runtime(wstring_view s) -> runtime_format_string<wchar_t> {
-  return {{s}};
-}
-#endif
-
-template <> struct is_char<wchar_t> : std::true_type {};
-template <> struct is_char<detail::char8_type> : std::true_type {};
-template <> struct is_char<char16_t> : std::true_type {};
-template <> struct is_char<char32_t> : std::true_type {};
-
-template <typename... T>
-constexpr format_arg_store<wformat_context, T...> make_wformat_args(
-    const T&... args) {
-  return {args...};
-}
-
-inline namespace literals {
-#if FMT_USE_USER_DEFINED_LITERALS && !FMT_USE_NONTYPE_TEMPLATE_ARGS
-constexpr detail::udl_arg<wchar_t> operator"" _a(const wchar_t* s, size_t) {
-  return {s};
-}
-#endif
-}  // namespace literals
-
-template <typename It, typename Sentinel>
-auto join(It begin, Sentinel end, wstring_view sep)
-    -> join_view<It, Sentinel, wchar_t> {
-  return {begin, end, sep};
-}
-
-template <typename Range>
-auto join(Range&& range, wstring_view sep)
-    -> join_view<detail::iterator_t<Range>, detail::sentinel_t<Range>,
-                 wchar_t> {
-  return join(std::begin(range), std::end(range), sep);
-}
-
-template <typename T>
-auto join(std::initializer_list<T> list, wstring_view sep)
-    -> join_view<const T*, const T*, wchar_t> {
-  return join(std::begin(list), std::end(list), sep);
-}
-
-template <typename Char, FMT_ENABLE_IF(!std::is_same<Char, char>::value)>
-auto vformat(basic_string_view<Char> format_str,
-             basic_format_args<buffer_context<type_identity_t<Char>>> args)
-    -> std::basic_string<Char> {
-  auto buf = basic_memory_buffer<Char>();
-  detail::vformat_to(buf, format_str, args);
-  return to_string(buf);
-}
-
-template <typename... T>
-auto format(wformat_string<T...> fmt, T&&... args) -> std::wstring {
-  return vformat(fmt::wstring_view(fmt), fmt::make_wformat_args(args...));
-}
-
-// Pass char_t as a default template parameter instead of using
-// std::basic_string<char_t<S>> to reduce the symbol size.
-template <typename S, typename... T, typename Char = char_t<S>,
-          FMT_ENABLE_IF(!std::is_same<Char, char>::value &&
-                        !std::is_same<Char, wchar_t>::value)>
-auto format(const S& format_str, T&&... args) -> std::basic_string<Char> {
-  return vformat(detail::to_string_view(format_str),
-                 fmt::make_format_args<buffer_context<Char>>(args...));
-}
-
-template <typename Locale, typename S, typename Char = char_t<S>,
-          FMT_ENABLE_IF(detail::is_locale<Locale>::value&&
-                            detail::is_exotic_char<Char>::value)>
-inline auto vformat(
-    const Locale& loc, const S& format_str,
-    basic_format_args<buffer_context<type_identity_t<Char>>> args)
-    -> std::basic_string<Char> {
-  return detail::vformat(loc, detail::to_string_view(format_str), args);
-}
-
-template <typename Locale, typename S, typename... T, typename Char = char_t<S>,
-          FMT_ENABLE_IF(detail::is_locale<Locale>::value&&
-                            detail::is_exotic_char<Char>::value)>
-inline auto format(const Locale& loc, const S& format_str, T&&... args)
-    -> std::basic_string<Char> {
-  return detail::vformat(loc, detail::to_string_view(format_str),
-                         fmt::make_format_args<buffer_context<Char>>(args...));
-}
-
-template <typename OutputIt, typename S, typename Char = char_t<S>,
-          FMT_ENABLE_IF(detail::is_output_iterator<OutputIt, Char>::value&&
-                            detail::is_exotic_char<Char>::value)>
-auto vformat_to(OutputIt out, const S& format_str,
-                basic_format_args<buffer_context<type_identity_t<Char>>> args)
-    -> OutputIt {
-  auto&& buf = detail::get_buffer<Char>(out);
-  detail::vformat_to(buf, detail::to_string_view(format_str), args);
-  return detail::get_iterator(buf, out);
-}
-
-template <typename OutputIt, typename S, typename... T,
-          typename Char = char_t<S>,
-          FMT_ENABLE_IF(detail::is_output_iterator<OutputIt, Char>::value&&
-                            detail::is_exotic_char<Char>::value)>
-inline auto format_to(OutputIt out, const S& fmt, T&&... args) -> OutputIt {
-  return vformat_to(out, detail::to_string_view(fmt),
-                    fmt::make_format_args<buffer_context<Char>>(args...));
-}
-
-template <typename Locale, typename S, typename OutputIt, typename... Args,
-          typename Char = char_t<S>,
-          FMT_ENABLE_IF(detail::is_output_iterator<OutputIt, Char>::value&&
-                            detail::is_locale<Locale>::value&&
-                                detail::is_exotic_char<Char>::value)>
-inline auto vformat_to(
-    OutputIt out, const Locale& loc, const S& format_str,
-    basic_format_args<buffer_context<type_identity_t<Char>>> args) -> OutputIt {
-  auto&& buf = detail::get_buffer<Char>(out);
-  vformat_to(buf, detail::to_string_view(format_str), args,
-             detail::locale_ref(loc));
-  return detail::get_iterator(buf, out);
-}
-
-template <
-    typename OutputIt, typename Locale, typename S, typename... T,
-    typename Char = char_t<S>,
-    bool enable = detail::is_output_iterator<OutputIt, Char>::value&&
-        detail::is_locale<Locale>::value&& detail::is_exotic_char<Char>::value>
-inline auto format_to(OutputIt out, const Locale& loc, const S& format_str,
-                      T&&... args) ->
-    typename std::enable_if<enable, OutputIt>::type {
-  return vformat_to(out, loc, detail::to_string_view(format_str),
-                    fmt::make_format_args<buffer_context<Char>>(args...));
-}
-
-template <typename OutputIt, typename Char, typename... Args,
-          FMT_ENABLE_IF(detail::is_output_iterator<OutputIt, Char>::value&&
-                            detail::is_exotic_char<Char>::value)>
-inline auto vformat_to_n(
-    OutputIt out, size_t n, basic_string_view<Char> format_str,
-    basic_format_args<buffer_context<type_identity_t<Char>>> args)
-    -> format_to_n_result<OutputIt> {
-  using traits = detail::fixed_buffer_traits;
-  auto buf = detail::iterator_buffer<OutputIt, Char, traits>(out, n);
-  detail::vformat_to(buf, format_str, args);
-  return {buf.out(), buf.count()};
-}
-
-template <typename OutputIt, typename S, typename... T,
-          typename Char = char_t<S>,
-          FMT_ENABLE_IF(detail::is_output_iterator<OutputIt, Char>::value&&
-                            detail::is_exotic_char<Char>::value)>
-inline auto format_to_n(OutputIt out, size_t n, const S& fmt, T&&... args)
-    -> format_to_n_result<OutputIt> {
-  return vformat_to_n(out, n, detail::to_string_view(fmt),
-                      fmt::make_format_args<buffer_context<Char>>(args...));
-}
-
-template <typename S, typename... T, typename Char = char_t<S>,
-          FMT_ENABLE_IF(detail::is_exotic_char<Char>::value)>
-inline auto formatted_size(const S& fmt, T&&... args) -> size_t {
-  auto buf = detail::counting_buffer<Char>();
-  detail::vformat_to(buf, detail::to_string_view(fmt),
-                     fmt::make_format_args<buffer_context<Char>>(args...));
-  return buf.count();
-}
-
-inline void vprint(std::FILE* f, wstring_view fmt, wformat_args args) {
-  auto buf = wmemory_buffer();
-  detail::vformat_to(buf, fmt, args);
-  buf.push_back(L'\0');
-  if (std::fputws(buf.data(), f) == -1)
-    FMT_THROW(system_error(errno, FMT_STRING("cannot write to file")));
-}
-
-inline void vprint(wstring_view fmt, wformat_args args) {
-  vprint(stdout, fmt, args);
-}
-
-template <typename... T>
-void print(std::FILE* f, wformat_string<T...> fmt, T&&... args) {
-  return vprint(f, wstring_view(fmt), fmt::make_wformat_args(args...));
-}
-
-template <typename... T> void print(wformat_string<T...> fmt, T&&... args) {
-  return vprint(wstring_view(fmt), fmt::make_wformat_args(args...));
-}
-
-template <typename... T>
-void println(std::FILE* f, wformat_string<T...> fmt, T&&... args) {
-  return print(f, L"{}\n", fmt::format(fmt, std::forward<T>(args)...));
-}
-
-template <typename... T> void println(wformat_string<T...> fmt, T&&... args) {
-  return print(L"{}\n", fmt::format(fmt, std::forward<T>(args)...));
-}
-
-/**
-  Converts *value* to ``std::wstring`` using the default format for type *T*.
- */
-template <typename T> inline auto to_wstring(const T& value) -> std::wstring {
-  return format(FMT_STRING(L"{}"), value);
-}
-FMT_END_EXPORT
-FMT_END_NAMESPACE
-
-#endif  // FMT_XCHAR_H_
diff --git a/lib/fmt/src/format.cc b/lib/fmt/src/format.cc
index c7ee308ef7..c9e00acdcd 100644
--- a/lib/fmt/src/format.cc
+++ b/lib/fmt/src/format.cc
@@ -10,34 +10,90 @@
 FMT_BEGIN_NAMESPACE
 namespace detail {
 
-template FMT_API auto dragonbox::to_decimal(float x) noexcept
-    -> dragonbox::decimal_fp<float>;
-template FMT_API auto dragonbox::to_decimal(double x) noexcept
-    -> dragonbox::decimal_fp<double>;
+template <typename T>
+int format_float(char* buf, std::size_t size, const char* format, int precision,
+                 T value) {
+#ifdef FMT_FUZZ
+  if (precision > 100000)
+    throw std::runtime_error(
+        "fuzz mode - avoid large allocation inside snprintf");
+#endif
+  // Suppress the warning about nonliteral format string.
+  int (*snprintf_ptr)(char*, size_t, const char*, ...) = FMT_SNPRINTF;
+  return precision < 0 ? snprintf_ptr(buf, size, format, value)
+                       : snprintf_ptr(buf, size, format, precision, value);
+}
+
+template FMT_API dragonbox::decimal_fp<float> dragonbox::to_decimal(float x)
+    FMT_NOEXCEPT;
+template FMT_API dragonbox::decimal_fp<double> dragonbox::to_decimal(double x)
+    FMT_NOEXCEPT;
+
+// DEPRECATED! This function exists for ABI compatibility.
+template <typename Char>
+typename basic_format_context<std::back_insert_iterator<buffer<Char>>,
+                              Char>::iterator
+vformat_to(buffer<Char>& buf, basic_string_view<Char> format_str,
+           basic_format_args<basic_format_context<
+               std::back_insert_iterator<buffer<type_identity_t<Char>>>,
+               type_identity_t<Char>>>
+               args) {
+  using iterator = std::back_insert_iterator<buffer<char>>;
+  using context = basic_format_context<
+      std::back_insert_iterator<buffer<type_identity_t<Char>>>,
+      type_identity_t<Char>>;
+  auto out = iterator(buf);
+  format_handler<iterator, Char, context> h(out, format_str, args, {});
+  parse_format_string<false>(format_str, h);
+  return out;
+}
+template basic_format_context<std::back_insert_iterator<buffer<char>>,
+                              char>::iterator
+vformat_to(buffer<char>&, string_view,
+           basic_format_args<basic_format_context<
+               std::back_insert_iterator<buffer<type_identity_t<char>>>,
+               type_identity_t<char>>>);
+}  // namespace detail
+
+template struct FMT_INSTANTIATION_DEF_API detail::basic_data<void>;
+
+// Workaround a bug in MSVC2013 that prevents instantiation of format_float.
+int (*instantiate_format_float)(double, int, detail::float_specs,
+                                detail::buffer<char>&) = detail::format_float;
 
 #ifndef FMT_STATIC_THOUSANDS_SEPARATOR
-template FMT_API locale_ref::locale_ref(const std::locale& loc);
-template FMT_API auto locale_ref::get<std::locale>() const -> std::locale;
+template FMT_API detail::locale_ref::locale_ref(const std::locale& loc);
+template FMT_API std::locale detail::locale_ref::get<std::locale>() const;
 #endif
 
 // Explicit instantiations for char.
 
-template FMT_API auto thousands_sep_impl(locale_ref)
-    -> thousands_sep_result<char>;
-template FMT_API auto decimal_point_impl(locale_ref) -> char;
+template FMT_API std::string detail::grouping_impl<char>(locale_ref);
+template FMT_API char detail::thousands_sep_impl(locale_ref);
+template FMT_API char detail::decimal_point_impl(locale_ref);
 
-template FMT_API void buffer<char>::append(const char*, const char*);
+template FMT_API void detail::buffer<char>::append(const char*, const char*);
 
-template FMT_API void vformat_to(buffer<char>&, string_view,
-                                 typename vformat_args<>::type, locale_ref);
+template FMT_API void detail::vformat_to(
+    detail::buffer<char>&, string_view,
+    basic_format_args<FMT_BUFFER_CONTEXT(char)>, detail::locale_ref);
 
-// Explicit instantiations for wchar_t.
+template FMT_API int detail::snprintf_float(double, int, detail::float_specs,
+                                            detail::buffer<char>&);
+template FMT_API int detail::snprintf_float(long double, int,
+                                            detail::float_specs,
+                                            detail::buffer<char>&);
+template FMT_API int detail::format_float(double, int, detail::float_specs,
+                                          detail::buffer<char>&);
+template FMT_API int detail::format_float(long double, int, detail::float_specs,
+                                          detail::buffer<char>&);
 
-template FMT_API auto thousands_sep_impl(locale_ref)
-    -> thousands_sep_result<wchar_t>;
-template FMT_API auto decimal_point_impl(locale_ref) -> wchar_t;
+// Explicit instantiations for wchar_t.
 
-template FMT_API void buffer<wchar_t>::append(const wchar_t*, const wchar_t*);
+template FMT_API std::string detail::grouping_impl<wchar_t>(locale_ref);
+template FMT_API wchar_t detail::thousands_sep_impl(locale_ref);
+template FMT_API wchar_t detail::decimal_point_impl(locale_ref);
 
-}  // namespace detail
+template FMT_API void detail::buffer<wchar_t>::append(const wchar_t*,
+                                                      const wchar_t*);
 FMT_END_NAMESPACE
diff --git a/src/vt/topos/index/dense/dense_array.h b/src/vt/topos/index/dense/dense_array.h
index 81b0f9fac8..df9c94045b 100644
--- a/src/vt/topos/index/dense/dense_array.h
+++ b/src/vt/topos/index/dense/dense_array.h
@@ -49,7 +49,6 @@
 #include "vt/utils/bits/bits_packer.h"
 #include "vt/utils/static_checks/meta_type_eq_.h"
 #include "vt/serialization/traits/byte_copy_trait.h"
-#include INCLUDE_FMT_RANGES
 
 #include <array>
 #include <type_traits>
@@ -147,7 +146,6 @@ struct DenseIndexArray : BaseIndex, serialization::ByteCopyTrait {
     std::ostream& os, DenseIndexArray<IndexT,nd> const& idx
   );
 
-  friend struct fmt::formatter<vt::index::DenseIndexArray<IndexType, ndim>>;
 private:
   std::array<IndexType, ndim> dims = {};
 };
@@ -163,12 +161,13 @@ VT_FMT_NAMESPACE_BEGIN
 
 template <typename IndexType, ::vt::index::NumDimensionsType ndim>
 struct formatter<::vt::index::DenseIndexArray<IndexType, ndim>>
-  : formatter<std::array<IndexType, ndim>> {
+  : formatter<std::string> {
   template <typename FormatContext>
   auto format(
-    const ::vt::index::DenseIndexArray<IndexType, ndim>& wrapper,
-    FormatContext& ctx) {
-    return formatter<std::array<IndexType, ndim>>::format(wrapper.dims, ctx);
+    const ::vt::index::DenseIndexArray<IndexType, ndim>& idx,
+    FormatContext& ctx
+  ) {
+    return formatter<std::string>::format(idx.toString(), ctx);
   }
 };