From dcc735aaeae1cc985a143ade883db748fb10554d Mon Sep 17 00:00:00 2001
From: Jonathan Wakely <jwakely@redhat.com>
Date: Fri, 5 Jul 2024 18:39:50 +0100
Subject: [PATCH] libstdc++: Restore support for including <name.h> in extern
"C" [PR115797]
The r15-1857 change means that <type_traits> is included by <cmath> for
C++17 and up, which breaks code including <math.h> inside an extern "C"
block. Although doing that is not allowed by the C++ standard, there's
lots of existing code which incorrectly thinks it's a good idea and so
we try to support it.
libstdc++-v3/ChangeLog:
PR libstdc++/115797
* include/std/type_traits: Ensure "C++" language linkage.
* testsuite/17_intro/headers/c++2011/linkage.cc: Replace
dg-options with c++11 target selector.
---
libstdc++-v3/include/std/type_traits | 3 +++
libstdc++-v3/testsuite/17_intro/headers/c++2011/linkage.cc | 3 +--
2 files changed, 4 insertions(+), 2 deletions(-)
diff --git a/libstdc++-v3/include/std/type_traits b/libstdc++-v3/include/std/type_traits
index a31de2ee4abb..c39a37925376 100644
--- a/libstdc++-v3/include/std/type_traits
+++ b/libstdc++-v3/include/std/type_traits
@@ -62,6 +62,8 @@
#define __glibcxx_want_void_t
#include <bits/version.h>
+extern "C++"
+{
namespace std _GLIBCXX_VISIBILITY(default)
{
_GLIBCXX_BEGIN_NAMESPACE_VERSION
@@ -4111,6 +4113,7 @@ template<typename _Ret, typename _Fn, typename... _Args>
_GLIBCXX_END_NAMESPACE_VERSION
} // namespace std
+} // extern "C++"
#endif // C++11
diff --git a/libstdc++-v3/testsuite/17_intro/headers/c++2011/linkage.cc b/libstdc++-v3/testsuite/17_intro/headers/c++2011/linkage.cc
index c43384efbaa9..1825801cec9c 100644
--- a/libstdc++-v3/testsuite/17_intro/headers/c++2011/linkage.cc
+++ b/libstdc++-v3/testsuite/17_intro/headers/c++2011/linkage.cc
@@ -15,8 +15,7 @@
// with this library; see the file COPYING3. If not see
// <http://www.gnu.org/licenses/>.
-// { dg-options "-std=gnu++11" }
-// { dg-do compile }
+// { dg-do compile { target c++11 } }
// libstdc++/69386
--
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