[llvm-branch-commits] [libcxx] release/18.x: [libc++] Only include <setjmp.h> from the C library if it exists (#81887) (PR #82045)

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llvmbot wrote:


<!--LLVM PR SUMMARY COMMENT-->

@llvm/pr-subscribers-libcxx

Author: None (llvmbot)

<details>
<summary>Changes</summary>

Backport d8278b6

Requested by: @<!-- -->ldionne

---
Full diff: https://github.com/llvm/llvm-project/pull/82045.diff


1 Files Affected:

- (modified) libcxx/include/csetjmp (+7-1) 


``````````diff
diff --git a/libcxx/include/csetjmp b/libcxx/include/csetjmp
index d219c8e6cb2250..9012cad22ebe74 100644
--- a/libcxx/include/csetjmp
+++ b/libcxx/include/csetjmp
@@ -33,7 +33,13 @@ void longjmp(jmp_buf env, int val);
 #include <__assert> // all public C++ headers provide the assertion handler
 #include <__config>
 
-#include <setjmp.h>
+// <setjmp.h> is not provided by libc++
+#if __has_include(<setjmp.h>)
+#  include <setjmp.h>
+#  ifdef _LIBCPP_SETJMP_H
+#    error "If libc++ starts defining <setjmp.h>, the __has_include check should move to libc++'s <setjmp.h>"
+#  endif
+#endif
 
 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
 #  pragma GCC system_header

``````````

</details>


https://github.com/llvm/llvm-project/pull/82045