[libcxx-commits] [libcxx] [libcxx] patch for implementing ranges::find_last (PR #67270)

[Christopher Di Bella via libcxx-commits]

================
@@ -0,0 +1,77 @@
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef _LIBCPP___ALGORITHM_RANGES_FIND_LAST_IF_H
+#define _LIBCPP___ALGORITHM_RANGES_FIND_LAST_IF_H
+
+#include <__config>
+#include <__functional/identity.h>
+#include <__functional/invoke.h>
+#include <__iterator/concepts.h>
+#include <__iterator/projected.h>
+#include <__ranges/access.h>
+#include <__ranges/concepts.h>
+#include <__ranges/dangling.h>
+#include <__ranges/range_adaptor.h>
+#include <__ranges/subrange.h>
+#include <__utility/move.h>
+
+#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
+#  pragma GCC system_header
+#endif
+
+#if _LIBCPP_STD_VER >= 23
+
+_LIBCPP_BEGIN_NAMESPACE_STD
+
+namespace ranges {
+
+template <class _Ip, class _Sp, class _Pred, class _Proj>
+_LIBCPP_NODISCARD_EXT _LIBCPP_HIDE_FROM_ABI static constexpr subrange<_Ip>
+__find_last_if_impl(_Ip __first, _Sp __last, _Pred __pred, _Proj __proj) {
+  _Ip __result = __last;
----------------
cjdb wrote:

This requires `assignable_from<_Ip&, _Sp&>`, so we need to use `ranges::next`.
```suggestion
  _Ip __result = ranges::next(__first, __last);
```

https://github.com/llvm/llvm-project/pull/67270