[gcc r14-9634] libstdc++: Use feature test macros in <bits/stl_construct.h>

[Jonathan Wakely <redi@gcc.gnu.org>]

https://gcc.gnu.org/g:8539c5610a7c36099af2ea756d8bbfa398a40e0b

commit r14-9634-g8539c5610a7c36099af2ea756d8bbfa398a40e0b
Author: Jonathan Wakely <jwakely@redhat.com>
Date:   Mon Mar 18 13:09:52 2024 +0000

    libstdc++: Use feature test macros in <bits/stl_construct.h>
    
    The preprocessor checks for __cplusplus in <bits/stl_construct.h> should
    use the appropriate feature test macros instead of __cplusplus, namely
    __glibcxx_raw_memory_algorithms and __cpp_constexpr_dynamic_alloc.
    
    For the latter, we want to check the compiler macro not the library's
    __cpp_lib_constexpr_dynamic_alloc, because the latter is not defined for
    freestanding but std::construct_at needs to be.
    
    libstdc++-v3/ChangeLog:
    
            * include/bits/stl_construct.h (destroy_at, construct_at): Guard
            with feature test macros instead of just __cplusplus.

Diff:
---
 libstdc++-v3/include/bits/stl_construct.h | 14 +++++++-------
 1 file changed, 7 insertions(+), 7 deletions(-)

diff --git a/libstdc++-v3/include/bits/stl_construct.h b/libstdc++-v3/include/bits/stl_construct.h
index 7c394072b50..dc08fb7ea33 100644
--- a/libstdc++-v3/include/bits/stl_construct.h
+++ b/libstdc++-v3/include/bits/stl_construct.h
@@ -74,7 +74,7 @@ namespace std _GLIBCXX_VISIBILITY(default)
 {
 _GLIBCXX_BEGIN_NAMESPACE_VERSION
 
-#if __cplusplus >= 201703L
+#if __glibcxx_raw_memory_algorithms // >= C++17
   template <typename _Tp>
     _GLIBCXX20_CONSTEXPR inline void
     destroy_at(_Tp* __location)
@@ -88,7 +88,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
 	__location->~_Tp();
     }
 
-#if __cplusplus >= 202002L
+#if __cpp_constexpr_dynamic_alloc // >= C++20
   template<typename _Tp, typename... _Args>
     constexpr auto
     construct_at(_Tp* __location, _Args&&... __args)
@@ -108,7 +108,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
     inline void
     _Construct(_Tp* __p, _Args&&... __args)
     {
-#if __cplusplus >= 202002L
+#if __cpp_constexpr_dynamic_alloc // >= C++20
       if (std::__is_constant_evaluated())
 	{
 	  // Allow std::_Construct to be used in constant expressions.
@@ -145,7 +145,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
     _GLIBCXX14_CONSTEXPR inline void
     _Destroy(_Tp* __pointer)
     {
-#if __cplusplus > 201703L
+#if __cpp_constexpr_dynamic_alloc // >= C++20
       std::destroy_at(__pointer);
 #else
       __pointer->~_Tp();
@@ -188,7 +188,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
       static_assert(is_destructible<_Value_type>::value,
 		    "value type is destructible");
 #endif
-#if __cplusplus >= 202002L
+#if __cpp_constexpr_dynamic_alloc // >= C++20
       if (std::__is_constant_evaluated())
 	return std::_Destroy_aux<false>::__destroy(__first, __last);
 #endif
@@ -237,7 +237,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
       static_assert(is_destructible<_Value_type>::value,
 		    "value type is destructible");
 #endif
-#if __cplusplus >= 202002L
+#if __cpp_constexpr_dynamic_alloc // >= C++20
       if (std::__is_constant_evaluated())
 	return std::_Destroy_n_aux<false>::__destroy_n(__first, __count);
 #endif
@@ -245,7 +245,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
 	__destroy_n(__first, __count);
     }
 
-#if __cplusplus >= 201703L
+#if __glibcxx_raw_memory_algorithms // >= C++17
   template <typename _ForwardIterator>
     _GLIBCXX20_CONSTEXPR inline void
     destroy(_ForwardIterator __first, _ForwardIterator __last)