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* [gcc r13-2954] libstdc++: Guard use of new built-in with __has_builtin
@ 2022-09-29 11:47 Jonathan Wakely
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From: Jonathan Wakely @ 2022-09-29 11:47 UTC (permalink / raw)
To: gcc-cvs, libstdc++-cvs
https://gcc.gnu.org/g:df7f2736509cfe5e1dd7d9f263355c5043347a9c
commit r13-2954-gdf7f2736509cfe5e1dd7d9f263355c5043347a9c
Author: Jonathan Wakely <jwakely@redhat.com>
Date: Thu Sep 29 11:30:05 2022 +0100
libstdc++: Guard use of new built-in with __has_builtin
I forgot that non-GCC compilers don't have this built-in yet.
For Clang we could do something like the check below (as described in
P2255), but for now I'm just fixing the regression.
#if __has_builtin((__reference_binds_to_temporary)
bool _Dangle = __reference_binds_to_temporary(_Tp, _Res_t)
&& __and_<is_reference<_Tp>,
__not_<is_reference<_Res_t>>,
is_convertible<__remove_cvref_t<_Res_t>*,
__remove_cvref_t<_Tp>*>>::value
#endif
libstdc++-v3/ChangeLog:
* include/std/type_traits (__is_invocable_impl): Check
__has_builtin(__reference_converts_from_temporary) before using
built-in.
Diff:
---
libstdc++-v3/include/std/type_traits | 7 ++++++-
1 file changed, 6 insertions(+), 1 deletion(-)
diff --git a/libstdc++-v3/include/std/type_traits b/libstdc++-v3/include/std/type_traits
index 22c1af26397..a015fd95a71 100644
--- a/libstdc++-v3/include/std/type_traits
+++ b/libstdc++-v3/include/std/type_traits
@@ -2901,7 +2901,12 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
template<typename _Tp,
bool _Nothrow = noexcept(_S_conv<_Tp>(_S_get())),
typename = decltype(_S_conv<_Tp>(_S_get())),
- bool _Dangle = __reference_converts_from_temporary(_Tp, _Res_t)>
+#if __has_builtin(__reference_converts_from_temporary)
+ bool _Dangle = __reference_converts_from_temporary(_Tp, _Res_t)
+#else
+ bool _Dangle = false
+#endif
+ >
static __bool_constant<_Nothrow && !_Dangle>
_S_test(int);
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