From 0bb1db32ccf54a9de59bea718f7575f7ef22abf5 Mon Sep 17 00:00:00 2001
From: Michael Levine <mlevine55@bloomberg.net>
Date: Fri, 7 Jun 2024 09:54:38 +0100
Subject: libstdc++: Fix std::ranges::iota is not included in numeric
 [PR108760]

Before this patch, using std::ranges::iota required including
<algorithm> when it should have been sufficient to only include
<numeric>.

libstdc++-v3/ChangeLog:

	PR libstdc++/108760
	* include/bits/ranges_algo.h (ranges::out_value_result):
	Move to <bits/ranges_algobase.h>.
	(ranges::iota_result, ranges::__iota_fn, ranges::iota): Move to
	<numeric>.
	* include/bits/ranges_algobase.h (ranges::out_value_result):
	Move to here.
	* include/std/numeric (ranges::iota_result, ranges::__iota_fn)
	(ranges::iota): Move to here.
	* testsuite/25_algorithms/iota/1.cc: Renamed to ...
	* testsuite/26_numerics/iota/2.cc: ... here.

Signed-off-by: Michael Levine <mlevine55@bloomberg.net>
---
 libstdc++-v3/include/std/numeric | 38 ++++++++++++++++++++++++++++++++++++++
 1 file changed, 38 insertions(+)

(limited to 'libstdc++-v3/include/std/numeric')

diff --git a/libstdc++-v3/include/std/numeric b/libstdc++-v3/include/std/numeric
index c912db4..201bb8e 100644
--- a/libstdc++-v3/include/std/numeric
+++ b/libstdc++-v3/include/std/numeric
@@ -89,6 +89,10 @@
 #define __glibcxx_want_saturation_arithmetic
 #include <bits/version.h>
 
+#if __glibcxx_ranges_iota >= 202202L // C++ >= 23
+# include <bits/ranges_algobase.h> // for ranges::out_value_result
+#endif
+
 #ifdef __glibcxx_saturation_arithmetic // C++ >= 26
 # include <bits/sat_arith.h>
 #endif
@@ -726,6 +730,40 @@ namespace __detail
   /// @} group numeric_ops
 #endif // C++17
 
+namespace ranges
+{
+#if __glibcxx_ranges_iota >= 202202L // C++ >= 23
+
+  template<typename _Out, typename _Tp>
+  using iota_result = out_value_result<_Out, _Tp>;
+
+  struct __iota_fn
+  {
+    template<input_or_output_iterator _Out, sentinel_for<_Out> _Sent, weakly_incrementable _Tp>
+      requires indirectly_writable<_Out, const _Tp&>
+      constexpr iota_result<_Out, _Tp>
+      operator()(_Out __first, _Sent __last, _Tp __value) const
+      {
+	while (__first != __last)
+	  {
+	    *__first = static_cast<const _Tp&>(__value);
+	    ++__first;
+	    ++__value;
+	  }
+	return {std::move(__first), std::move(__value)};
+      }
+
+    template<weakly_incrementable _Tp, output_range<const _Tp&> _Range>
+      constexpr iota_result<borrowed_iterator_t<_Range>, _Tp>
+      operator()(_Range&& __r, _Tp __value) const
+      { return (*this)(ranges::begin(__r), ranges::end(__r), std::move(__value)); }
+  };
+
+  inline constexpr __iota_fn iota{};
+
+#endif // __glibcxx_ranges_iota
+} // namespace ranges
+
 _GLIBCXX_END_NAMESPACE_VERSION
 } // namespace std
 
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