[llvm-branch-commits] [libcxx] 876a5c9 - [libc++] Avoid including <features.h> on arbitrary platforms (#125587)

[Tom Stellard via llvm-branch-commits]

Author: Louis Dionne
Date: 2025-02-19T06:26:51-08:00
New Revision: 876a5c9e5905a9666748632afba1ff83200ed95b

URL: https://github.com/llvm/llvm-project/commit/876a5c9e5905a9666748632afba1ff83200ed95b
DIFF: https://github.com/llvm/llvm-project/commit/876a5c9e5905a9666748632afba1ff83200ed95b.diff

LOG: [libc++] Avoid including <features.h> on arbitrary platforms (#125587)

This partially reverts commit 5f2389d4. That commit started checking
whether <features.h> was a valid include unconditionally, however codebases
are free to have such a header on their search path, which breaks compilation.
LLVM libc now provides a more standard way of getting configuration macros
like __LLVM_LIBC__.

After this patch, we only include <features.h> when we're on Linux or
when we're compiling for GPUs.

(cherry picked from commit cffc1ac3491c891ef4f80bcbfa685710e477eeac)

Added: 
    

Modified: 
    libcxx/include/__configuration/platform.h

Removed: 
    


################################################################################
diff  --git a/libcxx/include/__configuration/platform.h b/libcxx/include/__configuration/platform.h
index 2a92ce209b91f..cff99376ee24b 100644
--- a/libcxx/include/__configuration/platform.h
+++ b/libcxx/include/__configuration/platform.h
@@ -30,12 +30,9 @@
 // ... add new file formats here ...
 #endif
 
-// To detect which libc we're using
-#if __has_include(<features.h>)
+// Need to detect which libc we're using if we're on Linux.
+#if defined(__linux__) || defined(__AMDGPU__) || defined(__NVPTX__)
 #  include <features.h>
-#endif
-
-#if defined(__linux__)
 #  if defined(__GLIBC_PREREQ)
 #    define _LIBCPP_GLIBC_PREREQ(a, b) __GLIBC_PREREQ(a, b)
 #  else