From 86c24916b2c43049ae276154078a7463dfd5bee0 Mon Sep 17 00:00:00 2001
From: jzmaddock <john@johnmaddock.co.uk>
Date: Tue, 25 Oct 2022 18:51:29 +0100
Subject: [PATCH] Assert when features which require C++17 are compiled for an
 earlier C++ version. Also document C++17 requirement for norms.

---
 doc/vector_functionals/norms.qbk                          | 2 ++
 include/boost/math/ccmath/abs.hpp                         | 8 ++++++++
 include/boost/math/ccmath/div.hpp                         | 8 ++++++++
 include/boost/math/ccmath/fma.hpp                         | 8 ++++++++
 include/boost/math/ccmath/isfinite.hpp                    | 8 ++++++++
 include/boost/math/ccmath/isinf.hpp                       | 8 ++++++++
 include/boost/math/ccmath/isnan.hpp                       | 8 ++++++++
 include/boost/math/ccmath/isnormal.hpp                    | 8 ++++++++
 include/boost/math/ccmath/round.hpp                       | 8 ++++++++
 include/boost/math/ccmath/signbit.hpp                     | 8 ++++++++
 include/boost/math/differentiation/lanczos_smoothing.hpp  | 8 ++++++++
 .../empirical_cumulative_distribution_function.hpp        | 8 ++++++++
 include/boost/math/filters/daubechies.hpp                 | 8 ++++++++
 .../boost/math/special_functions/daubechies_scaling.hpp   | 8 ++++++++
 .../boost/math/special_functions/daubechies_wavelet.hpp   | 8 ++++++++
 include/boost/math/special_functions/rsqrt.hpp            | 8 ++++++++
 include/boost/math/statistics/signal_statistics.hpp       | 7 +++++++
 include/boost/math/tools/centered_continued_fraction.hpp  | 7 +++++++
 include/boost/math/tools/condition_numbers.hpp            | 8 ++++++++
 include/boost/math/tools/engel_expansion.hpp              | 8 ++++++++
 include/boost/math/tools/luroth_expansion.hpp             | 8 ++++++++
 include/boost/math/tools/norms.hpp                        | 8 ++++++++
 include/boost/math/tools/signal_statistics.hpp            | 8 ++++++++
 include/boost/math/tools/simple_continued_fraction.hpp    | 7 +++++++
 include/boost/math/tools/univariate_statistics.hpp        | 8 ++++++++
 25 files changed, 191 insertions(+)

diff --git a/doc/vector_functionals/norms.qbk b/doc/vector_functionals/norms.qbk
index b809540b16..e688c04b96 100644
--- a/doc/vector_functionals/norms.qbk
+++ b/doc/vector_functionals/norms.qbk
@@ -8,6 +8,8 @@
 
 [section:norms Norms]
 
+[note All of the functions below require at least C++17]
+
 [heading Synopsis]
 
 ``
diff --git a/include/boost/math/ccmath/abs.hpp b/include/boost/math/ccmath/abs.hpp
index 8e9317c517..1c9a6badd4 100644
--- a/include/boost/math/ccmath/abs.hpp
+++ b/include/boost/math/ccmath/abs.hpp
@@ -15,6 +15,14 @@
 #include <boost/math/ccmath/isnan.hpp>
 #include <boost/math/ccmath/isinf.hpp>
 
+#include <boost/math/tools/is_standalone.hpp>
+#ifndef BOOST_MATH_STANDALONE
+#include <boost/config.hpp>
+#ifdef BOOST_NO_CXX17_IF_CONSTEXPR
+#error "The header <boost/math/norms.hpp> can only be used in C++17 and later."
+#endif
+#endif
+
 namespace boost::math::ccmath {
 
 namespace detail {
diff --git a/include/boost/math/ccmath/div.hpp b/include/boost/math/ccmath/div.hpp
index 9553c7d397..3fb517be40 100644
--- a/include/boost/math/ccmath/div.hpp
+++ b/include/boost/math/ccmath/div.hpp
@@ -12,6 +12,14 @@
 #include <cstdint>
 #include <type_traits>
 
+#include <boost/math/tools/is_standalone.hpp>
+#ifndef BOOST_MATH_STANDALONE
+#include <boost/config.hpp>
+#ifdef BOOST_NO_CXX17_IF_CONSTEXPR
+#error "The header <boost/math/norms.hpp> can only be used in C++17 and later."
+#endif
+#endif
+
 namespace boost::math::ccmath {
 
 namespace detail {
diff --git a/include/boost/math/ccmath/fma.hpp b/include/boost/math/ccmath/fma.hpp
index 3056f76d47..7bc12fe7a6 100644
--- a/include/boost/math/ccmath/fma.hpp
+++ b/include/boost/math/ccmath/fma.hpp
@@ -13,6 +13,14 @@
 #include <boost/math/ccmath/isinf.hpp>
 #include <boost/math/ccmath/isnan.hpp>
 
+#include <boost/math/tools/is_standalone.hpp>
+#ifndef BOOST_MATH_STANDALONE
+#include <boost/config.hpp>
+#ifdef BOOST_NO_CXX17_IF_CONSTEXPR
+#error "The header <boost/math/norms.hpp> can only be used in C++17 and later."
+#endif
+#endif
+
 namespace boost::math::ccmath {
 
 namespace detail {
diff --git a/include/boost/math/ccmath/isfinite.hpp b/include/boost/math/ccmath/isfinite.hpp
index 717a14f44e..6b407bfa57 100644
--- a/include/boost/math/ccmath/isfinite.hpp
+++ b/include/boost/math/ccmath/isfinite.hpp
@@ -12,6 +12,14 @@
 #include <boost/math/ccmath/isinf.hpp>
 #include <boost/math/ccmath/isnan.hpp>
 
+#include <boost/math/tools/is_standalone.hpp>
+#ifndef BOOST_MATH_STANDALONE
+#include <boost/config.hpp>
+#ifdef BOOST_NO_CXX17_IF_CONSTEXPR
+#error "The header <boost/math/norms.hpp> can only be used in C++17 and later."
+#endif
+#endif
+
 namespace boost::math::ccmath {
 
 template <typename T>
diff --git a/include/boost/math/ccmath/isinf.hpp b/include/boost/math/ccmath/isinf.hpp
index 15787c25bc..d3e4358c4e 100644
--- a/include/boost/math/ccmath/isinf.hpp
+++ b/include/boost/math/ccmath/isinf.hpp
@@ -11,6 +11,14 @@
 #include <type_traits>
 #include <boost/math/tools/is_constant_evaluated.hpp>
 
+#include <boost/math/tools/is_standalone.hpp>
+#ifndef BOOST_MATH_STANDALONE
+#include <boost/config.hpp>
+#ifdef BOOST_NO_CXX17_IF_CONSTEXPR
+#error "The header <boost/math/norms.hpp> can only be used in C++17 and later."
+#endif
+#endif
+
 namespace boost::math::ccmath {
 
 template <typename T>
diff --git a/include/boost/math/ccmath/isnan.hpp b/include/boost/math/ccmath/isnan.hpp
index e56a2f3cb0..ca915a4642 100644
--- a/include/boost/math/ccmath/isnan.hpp
+++ b/include/boost/math/ccmath/isnan.hpp
@@ -10,6 +10,14 @@
 #include <type_traits>
 #include <boost/math/tools/is_constant_evaluated.hpp>
 
+#include <boost/math/tools/is_standalone.hpp>
+#ifndef BOOST_MATH_STANDALONE
+#include <boost/config.hpp>
+#ifdef BOOST_NO_CXX17_IF_CONSTEXPR
+#error "The header <boost/math/norms.hpp> can only be used in C++17 and later."
+#endif
+#endif
+
 namespace boost::math::ccmath {
 
 template <typename T>
diff --git a/include/boost/math/ccmath/isnormal.hpp b/include/boost/math/ccmath/isnormal.hpp
index f352a0466a..8310a65848 100644
--- a/include/boost/math/ccmath/isnormal.hpp
+++ b/include/boost/math/ccmath/isnormal.hpp
@@ -14,6 +14,14 @@
 #include <boost/math/ccmath/isinf.hpp>
 #include <boost/math/ccmath/isnan.hpp>
 
+#include <boost/math/tools/is_standalone.hpp>
+#ifndef BOOST_MATH_STANDALONE
+#include <boost/config.hpp>
+#ifdef BOOST_NO_CXX17_IF_CONSTEXPR
+#error "The header <boost/math/norms.hpp> can only be used in C++17 and later."
+#endif
+#endif
+
 namespace boost::math::ccmath {
 
 template <typename T>
diff --git a/include/boost/math/ccmath/round.hpp b/include/boost/math/ccmath/round.hpp
index 5c8c80eb9f..6b7947e646 100644
--- a/include/boost/math/ccmath/round.hpp
+++ b/include/boost/math/ccmath/round.hpp
@@ -15,6 +15,14 @@
 #include <boost/math/ccmath/isnan.hpp>
 #include <boost/math/ccmath/modf.hpp>
 
+#include <boost/math/tools/is_standalone.hpp>
+#ifndef BOOST_MATH_STANDALONE
+#include <boost/config.hpp>
+#ifdef BOOST_NO_CXX17_IF_CONSTEXPR
+#error "The header <boost/math/norms.hpp> can only be used in C++17 and later."
+#endif
+#endif
+
 namespace boost::math::ccmath {
 
 namespace detail {
diff --git a/include/boost/math/ccmath/signbit.hpp b/include/boost/math/ccmath/signbit.hpp
index 5e94496440..4c7bf5b2c5 100644
--- a/include/boost/math/ccmath/signbit.hpp
+++ b/include/boost/math/ccmath/signbit.hpp
@@ -16,6 +16,14 @@
 #include <boost/math/ccmath/isnan.hpp>
 #include <boost/math/ccmath/abs.hpp>
 
+#include <boost/math/tools/is_standalone.hpp>
+#ifndef BOOST_MATH_STANDALONE
+#include <boost/config.hpp>
+#ifdef BOOST_NO_CXX17_IF_CONSTEXPR
+#error "The header <boost/math/norms.hpp> can only be used in C++17 and later."
+#endif
+#endif
+
 #ifdef __has_include
 #  if __has_include(<bit>)
 #    include <bit>
diff --git a/include/boost/math/differentiation/lanczos_smoothing.hpp b/include/boost/math/differentiation/lanczos_smoothing.hpp
index a314288e48..1f18c2f6d5 100644
--- a/include/boost/math/differentiation/lanczos_smoothing.hpp
+++ b/include/boost/math/differentiation/lanczos_smoothing.hpp
@@ -14,6 +14,14 @@
 #include <type_traits>
 #include <boost/math/tools/assert.hpp>
 
+#include <boost/math/tools/is_standalone.hpp>
+#ifndef BOOST_MATH_STANDALONE
+#include <boost/config.hpp>
+#ifdef BOOST_NO_CXX17_IF_CONSTEXPR
+#error "The header <boost/math/norms.hpp> can only be used in C++17 and later."
+#endif
+#endif
+
 namespace boost::math::differentiation {
 
 namespace detail {
diff --git a/include/boost/math/distributions/empirical_cumulative_distribution_function.hpp b/include/boost/math/distributions/empirical_cumulative_distribution_function.hpp
index ac1e4bee08..767ea2e323 100644
--- a/include/boost/math/distributions/empirical_cumulative_distribution_function.hpp
+++ b/include/boost/math/distributions/empirical_cumulative_distribution_function.hpp
@@ -11,6 +11,14 @@
 #include <type_traits>
 #include <utility>
 
+#include <boost/math/tools/is_standalone.hpp>
+#ifndef BOOST_MATH_STANDALONE
+#include <boost/config.hpp>
+#ifdef BOOST_NO_CXX17_IF_CONSTEXPR
+#error "The header <boost/math/norms.hpp> can only be used in C++17 and later."
+#endif
+#endif
+
 namespace boost { namespace math{
 
 template<class RandomAccessContainer>
diff --git a/include/boost/math/filters/daubechies.hpp b/include/boost/math/filters/daubechies.hpp
index 0dc4b5bf5c..0fdeac6a34 100644
--- a/include/boost/math/filters/daubechies.hpp
+++ b/include/boost/math/filters/daubechies.hpp
@@ -10,6 +10,14 @@
 #include <limits>
 #include <boost/math/tools/big_constant.hpp>
 
+#include <boost/math/tools/is_standalone.hpp>
+#ifndef BOOST_MATH_STANDALONE
+#include <boost/config.hpp>
+#ifdef BOOST_NO_CXX17_IF_CONSTEXPR
+#error "The header <boost/math/norms.hpp> can only be used in C++17 and later."
+#endif
+#endif
+
 namespace boost::math::filters {
 
 template <typename Real, unsigned p>
diff --git a/include/boost/math/special_functions/daubechies_scaling.hpp b/include/boost/math/special_functions/daubechies_scaling.hpp
index 503a5446e2..069b35a0ed 100644
--- a/include/boost/math/special_functions/daubechies_scaling.hpp
+++ b/include/boost/math/special_functions/daubechies_scaling.hpp
@@ -19,6 +19,14 @@
 #include <boost/math/interpolators/detail/quintic_hermite_detail.hpp>
 #include <boost/math/interpolators/detail/septic_hermite_detail.hpp>
 
+#include <boost/math/tools/is_standalone.hpp>
+#ifndef BOOST_MATH_STANDALONE
+#include <boost/config.hpp>
+#ifdef BOOST_NO_CXX17_IF_CONSTEXPR
+#error "The header <boost/math/norms.hpp> can only be used in C++17 and later."
+#endif
+#endif
+
 namespace boost::math {
 
 template<class Real, int p, int order>
diff --git a/include/boost/math/special_functions/daubechies_wavelet.hpp b/include/boost/math/special_functions/daubechies_wavelet.hpp
index d1e3f5609b..d12a6df6b6 100644
--- a/include/boost/math/special_functions/daubechies_wavelet.hpp
+++ b/include/boost/math/special_functions/daubechies_wavelet.hpp
@@ -21,6 +21,14 @@
 #include <boost/math/interpolators/detail/quintic_hermite_detail.hpp>
 #include <boost/math/interpolators/detail/septic_hermite_detail.hpp>
 
+#include <boost/math/tools/is_standalone.hpp>
+#ifndef BOOST_MATH_STANDALONE
+#include <boost/config.hpp>
+#ifdef BOOST_NO_CXX17_IF_CONSTEXPR
+#error "The header <boost/math/norms.hpp> can only be used in C++17 and later."
+#endif
+#endif
+
 namespace boost::math {
 
    template<class Real, int p, int order>
diff --git a/include/boost/math/special_functions/rsqrt.hpp b/include/boost/math/special_functions/rsqrt.hpp
index 3b8be82352..438d16fb0c 100644
--- a/include/boost/math/special_functions/rsqrt.hpp
+++ b/include/boost/math/special_functions/rsqrt.hpp
@@ -9,6 +9,14 @@
 #include <type_traits>
 #include <limits>
 
+#include <boost/math/tools/is_standalone.hpp>
+#ifndef BOOST_MATH_STANDALONE
+#include <boost/config.hpp>
+#ifdef BOOST_NO_CXX17_IF_CONSTEXPR
+#error "The header <boost/math/norms.hpp> can only be used in C++17 and later."
+#endif
+#endif
+
 namespace boost::math {
 
 template<typename Real>
diff --git a/include/boost/math/statistics/signal_statistics.hpp b/include/boost/math/statistics/signal_statistics.hpp
index c11e802c30..ebde0f8bb2 100644
--- a/include/boost/math/statistics/signal_statistics.hpp
+++ b/include/boost/math/statistics/signal_statistics.hpp
@@ -13,6 +13,13 @@
 #include <boost/math/tools/roots.hpp>
 #include <boost/math/statistics/univariate_statistics.hpp>
 
+#include <boost/math/tools/is_standalone.hpp>
+#ifndef BOOST_MATH_STANDALONE
+#include <boost/config.hpp>
+#ifdef BOOST_NO_CXX17_IF_CONSTEXPR
+#error "The header <boost/math/norms.hpp> can only be used in C++17 and later."
+#endif
+#endif
 
 namespace boost::math::statistics {
 
diff --git a/include/boost/math/tools/centered_continued_fraction.hpp b/include/boost/math/tools/centered_continued_fraction.hpp
index 0493142de5..1bb095c8fd 100644
--- a/include/boost/math/tools/centered_continued_fraction.hpp
+++ b/include/boost/math/tools/centered_continued_fraction.hpp
@@ -18,6 +18,13 @@
 #include <type_traits>
 #include <boost/math/tools/is_standalone.hpp>
 
+#ifndef BOOST_MATH_STANDALONE
+#include <boost/config.hpp>
+#ifdef BOOST_NO_CXX17_IF_CONSTEXPR
+#error "The header <boost/math/norms.hpp> can only be used in C++17 and later."
+#endif
+#endif
+
 #ifndef BOOST_MATH_STANDALONE
 #include <boost/core/demangle.hpp>
 #endif
diff --git a/include/boost/math/tools/condition_numbers.hpp b/include/boost/math/tools/condition_numbers.hpp
index 8754d12828..5894f20b78 100644
--- a/include/boost/math/tools/condition_numbers.hpp
+++ b/include/boost/math/tools/condition_numbers.hpp
@@ -9,6 +9,14 @@
 #include <limits>
 #include <boost/math/differentiation/finite_difference.hpp>
 
+#include <boost/math/tools/is_standalone.hpp>
+#ifndef BOOST_MATH_STANDALONE
+#include <boost/config.hpp>
+#ifdef BOOST_NO_CXX17_IF_CONSTEXPR
+#error "The header <boost/math/norms.hpp> can only be used in C++17 and later."
+#endif
+#endif
+
 namespace boost::math::tools {
 
 template<class Real, bool kahan=true>
diff --git a/include/boost/math/tools/engel_expansion.hpp b/include/boost/math/tools/engel_expansion.hpp
index 643d469dee..4e54988be8 100644
--- a/include/boost/math/tools/engel_expansion.hpp
+++ b/include/boost/math/tools/engel_expansion.hpp
@@ -14,6 +14,14 @@
 #include <limits>
 #include <stdexcept>
 
+#include <boost/math/tools/is_standalone.hpp>
+#ifndef BOOST_MATH_STANDALONE
+#include <boost/config.hpp>
+#ifdef BOOST_NO_CXX17_IF_CONSTEXPR
+#error "The header <boost/math/norms.hpp> can only be used in C++17 and later."
+#endif
+#endif
+
 namespace boost::math::tools {
 
 template<typename Real, typename Z = int64_t>
diff --git a/include/boost/math/tools/luroth_expansion.hpp b/include/boost/math/tools/luroth_expansion.hpp
index 7fb486b865..6cc6f9abdc 100644
--- a/include/boost/math/tools/luroth_expansion.hpp
+++ b/include/boost/math/tools/luroth_expansion.hpp
@@ -13,6 +13,14 @@
 #include <limits>
 #include <stdexcept>
 
+#include <boost/math/tools/is_standalone.hpp>
+#ifndef BOOST_MATH_STANDALONE
+#include <boost/config.hpp>
+#ifdef BOOST_NO_CXX17_IF_CONSTEXPR
+#error "The header <boost/math/norms.hpp> can only be used in C++17 and later."
+#endif
+#endif
+
 namespace boost::math::tools {
 
 template<typename Real, typename Z = int64_t>
diff --git a/include/boost/math/tools/norms.hpp b/include/boost/math/tools/norms.hpp
index 073ad80cfa..ad444bae42 100644
--- a/include/boost/math/tools/norms.hpp
+++ b/include/boost/math/tools/norms.hpp
@@ -12,6 +12,14 @@
 #include <boost/math/tools/assert.hpp>
 #include <boost/math/tools/complex.hpp>
 
+#include <boost/math/tools/is_standalone.hpp>
+#ifndef BOOST_MATH_STANDALONE
+#include <boost/config.hpp>
+#ifdef BOOST_NO_CXX17_IF_CONSTEXPR
+#error "The header <boost/math/norms.hpp> can only be used in C++17 and later."
+#endif
+#endif
+
 
 namespace boost::math::tools {
 
diff --git a/include/boost/math/tools/signal_statistics.hpp b/include/boost/math/tools/signal_statistics.hpp
index d553192f01..382844c195 100644
--- a/include/boost/math/tools/signal_statistics.hpp
+++ b/include/boost/math/tools/signal_statistics.hpp
@@ -14,6 +14,14 @@
 #include <boost/math/tools/header_deprecated.hpp>
 #include <boost/math/statistics/univariate_statistics.hpp>
 
+#include <boost/math/tools/is_standalone.hpp>
+#ifndef BOOST_MATH_STANDALONE
+#include <boost/config.hpp>
+#ifdef BOOST_NO_CXX17_IF_CONSTEXPR
+#error "The header <boost/math/norms.hpp> can only be used in C++17 and later."
+#endif
+#endif
+
 BOOST_MATH_HEADER_DEPRECATED("<boost/math/statistics/signal_statistics.hpp>");
 
 namespace boost::math::tools {
diff --git a/include/boost/math/tools/simple_continued_fraction.hpp b/include/boost/math/tools/simple_continued_fraction.hpp
index fad654533d..0fe17fc59d 100644
--- a/include/boost/math/tools/simple_continued_fraction.hpp
+++ b/include/boost/math/tools/simple_continued_fraction.hpp
@@ -14,7 +14,14 @@
 #include <limits>
 #include <stdexcept>
 #include <sstream>
+
 #include <boost/math/tools/is_standalone.hpp>
+#ifndef BOOST_MATH_STANDALONE
+#include <boost/config.hpp>
+#ifdef BOOST_NO_CXX17_IF_CONSTEXPR
+#error "The header <boost/math/norms.hpp> can only be used in C++17 and later."
+#endif
+#endif
 
 #ifndef BOOST_MATH_STANDALONE
 #include <boost/core/demangle.hpp>
diff --git a/include/boost/math/tools/univariate_statistics.hpp b/include/boost/math/tools/univariate_statistics.hpp
index 36f9d44fcf..1091d9f6e4 100644
--- a/include/boost/math/tools/univariate_statistics.hpp
+++ b/include/boost/math/tools/univariate_statistics.hpp
@@ -12,6 +12,14 @@
 #include <boost/math/tools/assert.hpp>
 #include <boost/math/tools/header_deprecated.hpp>
 
+#include <boost/math/tools/is_standalone.hpp>
+#ifndef BOOST_MATH_STANDALONE
+#include <boost/config.hpp>
+#ifdef BOOST_NO_CXX17_IF_CONSTEXPR
+#error "The header <boost/math/norms.hpp> can only be used in C++17 and later."
+#endif
+#endif
+
 BOOST_MATH_HEADER_DEPRECATED("<boost/math/statistics/univariate_statistics.hpp>");
 
 namespace boost::math::tools {