[libc-commits] [PATCH] D158128: [libc] [NFC] explain compiler macros in limits.h

[Alfred Persson Forsberg via Phabricator via libc-commits]

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Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D158128

Files:
  libc/include/llvm-libc-macros/limits-macros.h


Index: libc/include/llvm-libc-macros/limits-macros.h
===================================================================
--- libc/include/llvm-libc-macros/limits-macros.h
+++ libc/include/llvm-libc-macros/limits-macros.h
@@ -1,6 +1,12 @@
 #ifndef __LLVM_LIBC_MACROS_LIMITS_MACROS_H
 #define __LLVM_LIBC_MACROS_LIMITS_MACROS_H
 
+// Normally compiler headers will be prefered over LLVM-libc headers and
+// include_next this header, however, during LLVM-libc build itself the
+// LLVM-libc headers are prefered, and to get C numerical limits we need to
+// include compiler (freestanding) limits.h. The macro checks are here to avoid
+// including limits.h when compiler headers have already been included.
+
 #if !defined _GCC_LIMITS_H_ && !defined __CLANG_LIMITS_H &&                    \
     __has_include_next(<limits.h>)
 #include_next <limits.h>


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