From 8d14291e92d8dad7cab63161e14c61b0e2d71e33 Mon Sep 17 00:00:00 2001
From: Jonathan Wakely <cxx@kayari.org>
Date: Mon, 23 Jun 2025 17:38:37 +0100
Subject: [PATCH] P3060R3 Add std::views::indices(n)

Fixed "if T models is-integer-like" which is a category error because
that's a variable template not a concept.
---
 source/ranges.tex  | 16 +++++++++++++++-
 source/support.tex |  1 +
 2 files changed, 16 insertions(+), 1 deletion(-)

diff --git a/source/ranges.tex b/source/ranges.tex
index c16eba7f10..7d35652947 100644
--- a/source/ranges.tex
+++ b/source/ranges.tex
@@ -215,7 +215,10 @@
   template<class W, class Bound>
     constexpr bool @\libspec{enable_borrowed_range}{iota_view}@<iota_view<W, Bound>> = true;
 
-  namespace views { inline constexpr @\unspecnc@ iota = @\unspecnc@; }
+  namespace views {
+    inline constexpr @\unspecnc@ iota = @\unspecnc@;
+    inline constexpr @\unspecnc@ indices = @\unspecnc@;
+  }
 
   // \ref{range.repeat}, repeat view
   template<@\libconcept{move_constructible}@ T, @\libconcept{semiregular}@ Bound = unreachable_sentinel_t>
@@ -2784,6 +2787,17 @@
 \end{codeblock}
 \end{example}
 
+\pnum
+\indexlibrarymember{indices}{views}%
+The name \tcode{views::indices} denotes a
+customization point object\iref{customization.point.object}.
+Given subexpression \tcode{E},
+let \tcode{T} be \tcode{remove_cvref_t<decltype((E))>}.
+\tcode{views::indices(E)} is expression-equivalent to
+\tcode{views::iota(T(0), E)}
+if \tcode{\exposid{is-integer-like}<T>} is \tcode{true},
+and ill-formed otherwise.
+
 \rSec3[range.iota.view]{Class template \tcode{iota_view}}
 
 \indexlibraryglobal{iota_view}%
diff --git a/source/support.tex b/source/support.tex
index 95d674aafb..9e40765ab5 100644
--- a/source/support.tex
+++ b/source/support.tex
@@ -775,6 +775,7 @@
 #define @\defnlibxname{cpp_lib_ranges_find_last}@                  202207L // also in \libheader{algorithm}
 #define @\defnlibxname{cpp_lib_ranges_fold}@                       202207L // also in \libheader{algorithm}
 #define @\defnlibxname{cpp_lib_ranges_generate_random}@            202403L // also in \libheader{random}
+#define @\defnlibxname{cpp_lib_ranges_indices}@                    202506L // also in \libheader{ranges}
 #define @\defnlibxname{cpp_lib_ranges_iota}@                       202202L // also in \libheader{numeric}
 #define @\defnlibxname{cpp_lib_ranges_join_with}@                  202202L // freestanding, also in \libheader{ranges}
 #define @\defnlibxname{cpp_lib_ranges_repeat}@                     202207L // freestanding, also in \libheader{ranges}