[clang] [clang] Define ATOMIC_FLAG_INIT correctly for C++. (PR #97534)

[via cfe-commits]

llvmbot wrote:


<!--LLVM PR SUMMARY COMMENT-->

@llvm/pr-subscribers-clang

Author: Chris Copeland (chrisnc)

<details>
<summary>Changes</summary>



---
Full diff: https://github.com/llvm/llvm-project/pull/97534.diff


2 Files Affected:

- (modified) clang/docs/ReleaseNotes.rst (+2) 
- (modified) clang/lib/Headers/stdatomic.h (+4) 


``````````diff
diff --git a/clang/docs/ReleaseNotes.rst b/clang/docs/ReleaseNotes.rst
index 1537eaaba0c66..3d85065a7ff8a 100644
--- a/clang/docs/ReleaseNotes.rst
+++ b/clang/docs/ReleaseNotes.rst
@@ -750,6 +750,8 @@ Bug Fixes in This Version
 
 - Fixed `static_cast` to array of unknown bound. Fixes (#GH62863).
 
+- Fixed the definition of ATOMIC_FLAG_INIT in stdatomic.h so it can be used in C++.
+
 Bug Fixes to Compiler Builtins
 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
diff --git a/clang/lib/Headers/stdatomic.h b/clang/lib/Headers/stdatomic.h
index 9c103d98af8c5..88172038be5c4 100644
--- a/clang/lib/Headers/stdatomic.h
+++ b/clang/lib/Headers/stdatomic.h
@@ -166,7 +166,11 @@ typedef _Atomic(uintmax_t)          atomic_uintmax_t;
 
 typedef struct atomic_flag { atomic_bool _Value; } atomic_flag;
 
+#ifdef __cplusplus
+#define ATOMIC_FLAG_INIT { false }
+#else
 #define ATOMIC_FLAG_INIT { 0 }
+#endif
 
 /* These should be provided by the libc implementation. */
 #ifdef __cplusplus

``````````

</details>


https://github.com/llvm/llvm-project/pull/97534