From: Jonathan Wakely <jwakely@redhat.com>
Date: Fri, 4 Feb 2022 19:42:19 +0000 (+0000)
Subject: libstdc++: Allow Clang to use <stdatomic.h> before C++23
X-Git-Tag: upstream/12.2.0~1633
X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=0d1aabb60ec66bffbc9a3269f6ca85150f259564;p=platform%2Fupstream%2Fgcc.git

libstdc++: Allow Clang to use <stdatomic.h> before C++23

There is code that only expects to be compiled with clang++ and uses its
<stdatomic.h>, which works because Clang supports the _Atomic specifier
in C++. The addition  of <stdatomic.h> to libstdc++ broke this code, as
now it finds the C++ header instead, which is empty for any standard
mode before C++23.

This change allows that code to keep working as before, by forwarding to
clang's <stdatomic.h>.

libstdc++-v3/ChangeLog:

	* include/c_compatibility/stdatomic.h [__clang__]: Use
	#include_next <stdatomic.h>.
---

diff --git a/libstdc++-v3/include/c_compatibility/stdatomic.h b/libstdc++-v3/include/c_compatibility/stdatomic.h
index 852574b..95c7261 100644
--- a/libstdc++-v3/include/c_compatibility/stdatomic.h
+++ b/libstdc++-v3/include/c_compatibility/stdatomic.h
@@ -120,5 +120,7 @@ using std::atomic_flag_clear_explicit;
 using std::atomic_thread_fence;
 using std::atomic_signal_fence;
 
+#elif defined __clang__
+# include_next <stdatomic.h>
 #endif // C++23
 #endif // _GLIBCXX_STDATOMIC_H