[llvm-branch-commits] [libcxx] release/20.x: [libc++] Guard include of <features.h> with __has_include (#127691) (PR #127842)

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llvmbot wrote:


<!--LLVM PR SUMMARY COMMENT-->

@llvm/pr-subscribers-libcxx

Author: None (llvmbot)

<details>
<summary>Changes</summary>

Backport 2c8b1248513624e89b510397224f0f405116f3d3

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

---
Full diff: https://github.com/llvm/llvm-project/pull/127842.diff


1 Files Affected:

- (modified) libcxx/include/__configuration/platform.h (+8-6) 


``````````diff
diff --git a/libcxx/include/__configuration/platform.h b/libcxx/include/__configuration/platform.h
index cff99376ee24b..8d0f8f63f5213 100644
--- a/libcxx/include/__configuration/platform.h
+++ b/libcxx/include/__configuration/platform.h
@@ -32,12 +32,14 @@
 
 // Need to detect which libc we're using if we're on Linux.
 #if defined(__linux__) || defined(__AMDGPU__) || defined(__NVPTX__)
-#  include <features.h>
-#  if defined(__GLIBC_PREREQ)
-#    define _LIBCPP_GLIBC_PREREQ(a, b) __GLIBC_PREREQ(a, b)
-#  else
-#    define _LIBCPP_GLIBC_PREREQ(a, b) 0
-#  endif // defined(__GLIBC_PREREQ)
+#  if __has_include(<features.h>)
+#    include <features.h>
+#    if defined(__GLIBC_PREREQ)
+#      define _LIBCPP_GLIBC_PREREQ(a, b) __GLIBC_PREREQ(a, b)
+#    else
+#      define _LIBCPP_GLIBC_PREREQ(a, b) 0
+#    endif // defined(__GLIBC_PREREQ)
+#  endif
 #endif
 
 #ifndef __BYTE_ORDER__

``````````

</details>


https://github.com/llvm/llvm-project/pull/127842