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From: Jonathan Wakely <>
Subject: [committed] libstdc++: Guard use of new built-in with __has_builtin
Date: Thu, 29 Sep 2022 12:54:23 +0100	[thread overview]
Message-ID: <> (raw)
In-Reply-To: <>

This fixes libstdc++ for Clang and other non-GCC compilers.

Tested powerpc64le-linux. Pushed to trunk as r13-2954-gdf7f2736509cfe.

-- >8 --

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>,


	* include/std/type_traits (__is_invocable_impl): Check
	__has_builtin(__reference_converts_from_temporary) before using
 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
       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)
+	       bool _Dangle = false
+	      >
 	static __bool_constant<_Nothrow && !_Dangle>

  reply	other threads:[~2022-09-29 11:54 UTC|newest]

Thread overview: 3+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-09-28 23:35 [committed] libstdc++: Make INVOKE<R> refuse to create dangling references [PR70692] Jonathan Wakely
2022-09-29 11:54 ` Jonathan Wakely [this message]
2022-10-05 12:46 [committed] libstdc++: Guard use of new built-in with __has_builtin Jonathan Wakely

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