[libc] Make headers compatible with C++ < 11

[frobtech]

C++11 introduced noexcept, but throw() can be used in older
versions of the language.

[llvmbot]

@llvm/pr-subscribers-libc

Author: Roland McGrath (frobtech)

Changes

C++11 introduced noexcept, but throw() can be used in older
versions of the language.

---

Full diff: https://github.com/llvm/llvm-project/pull/123260.diff

1 Files Affected:

• (modified) libc/include/__llvm-libc-common.h (+4)

diff --git a/libc/include/__llvm-libc-common.h b/libc/include/__llvm-libc-common.h
index c63eb134a5e5d7..b5a23c5765f4d8 100644
--- a/libc/include/__llvm-libc-common.h
+++ b/libc/include/__llvm-libc-common.h
@@ -39,7 +39,11 @@
 #define _Thread_local thread_local
 
 #undef __NOEXCEPT
+#if __cplusplus >= 201103L
 #define __NOEXCEPT noexcept
+#else
+#define __NOEXCEPT throw()
+#endif
 
 #else // not __cplusplus