On 7/15/22 22:25, Marek Polacek via Gcc-patches wrote:
Yeah, I guess so. But I've already pushed the patch.
This commit obviously breaks using libstdc++ with Clang (in -std=c++2b
mode), which doesn't implement those new builtins. Something like the
below would fix that,
diff --git a/libstdc++-v3/include/std/type_traits
b/libstdc++-v3/include/std/type_traits
index b1a1deecf66..a6e028b42ec 100644
--- a/libstdc++-v3/include/std/type_traits
+++ b/libstdc++-v3/include/std/type_traits
@@ -3505,6 +3505,7 @@ template<typename _Ret, typename _Fn, typename... _Args>
template<typename _Tp>
inline constexpr bool is_scoped_enum_v = is_scoped_enum<_Tp>::value;
+#if __has_builtin(__reference_constructs_from_temporary) && __has_builtin(__reference_converts_from_temporary)
#define __cpp_lib_reference_from_temporary 202202L
/// True if _Tp is a reference type, a _Up value can be bound to _Tp in
@@ -3544,6 +3545,7 @@ template<typename _Ret, typename _Fn, typename... _Args>
template<typename _Tp, typename _Up>
inline constexpr bool reference_converts_from_temporary_v
= reference_converts_from_temporary<_Tp, _Up>::value;
+#endif
#endif // C++23
#if _GLIBCXX_HAVE_IS_CONSTANT_EVALUATED
diff --git a/libstdc++-v3/include/std/version b/libstdc++-v3/include/std/version
index 5edca2f3007..7c4b7f7cc6d 100644
--- a/libstdc++-v3/include/std/version
+++ b/libstdc++-v3/include/std/version
@@ -304,7 +304,9 @@
#define __cpp_lib_byteswap 202110L
#define __cpp_lib_constexpr_typeinfo 202106L
#define __cpp_lib_is_scoped_enum 202011L
+#if __has_builtin(__reference_constructs_from_temporary) &&
__has_builtin(__reference_converts_from_temporary)
#define __cpp_lib_reference_from_temporary 202202L
+#endif
#if _GLIBCXX_HOSTED
#define __cpp_lib_adaptor_iterator_pair_constructor 202106L
