[libc-commits] [libc] [libc] Define away __restrict in C++ without GNU extensions (PR #114655)

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llvmbot wrote:


<!--LLVM PR SUMMARY COMMENT-->

@llvm/pr-subscribers-libc

Author: Roland McGrath (frobtech)

<details>
<summary>Changes</summary>

The C99 restrict keyword is spelled __restrict in the libc
headers so it can be parsed by C++ compilers with GNU extensions
that recognize it.  When GNU extensions are not available in C++


---
Full diff: https://github.com/llvm/llvm-project/pull/114655.diff


1 Files Affected:

- (modified) libc/include/__llvm-libc-common.h (+6) 


``````````diff
diff --git a/libc/include/__llvm-libc-common.h b/libc/include/__llvm-libc-common.h
index 3af0b08e9e8668..e0e29bbbd5f87c 100644
--- a/libc/include/__llvm-libc-common.h
+++ b/libc/include/__llvm-libc-common.h
@@ -17,6 +17,12 @@
 #undef __END_C_DECLS
 #define __END_C_DECLS }
 
+// Standard C++ doesn't have C99 restrict but GNU C++ has it with __ spelling.
+#undef __restrict
+#ifndef __GNUC__
+#define __restrict
+#endif
+
 #undef _Noreturn
 #define _Noreturn [[noreturn]]
 

``````````

</details>


https://github.com/llvm/llvm-project/pull/114655