[libc] Use __SIZEOF_LONG__ to define LONG_WIDTH instead of sizeof(long).

[lntue]

The standard requires limits.h constants to be used in preprocessors. So we use __SIZEOF_LONG__ instead of sizeof(long) to define LONG_WIDTH. The macro __SIZEOF_LONG__ seems to be available on both clang and gcc since at least version 9.

[llvmbot]

@llvm/pr-subscribers-libc

Author: None (lntue)

Changes

The standard requires limits.h constants to be used in preprocessors. So we use __SIZEOF_LONG__ instead of sizeof(long) to define LONG_WIDTH. The macro __SIZEOF_LONG__ seems to be available on both clang and gcc since at least version 9.

---

Full diff: https://github.com/llvm/llvm-project/pull/79391.diff

1 Files Affected:

• (modified) libc/include/llvm-libc-macros/limits-macros.h (+3-2)

diff --git a/libc/include/llvm-libc-macros/limits-macros.h b/libc/include/llvm-libc-macros/limits-macros.h
index 3ccfbff79932904..3b4df58ae4a1430 100644
--- a/libc/include/llvm-libc-macros/limits-macros.h
+++ b/libc/include/llvm-libc-macros/limits-macros.h
@@ -70,8 +70,9 @@
 #elif defined(__WORDSIZE)
 #define LONG_WIDTH __WORDSIZE
 #else
-// Use sizeof(long) * CHAR_BIT as backup. This is needed for clang-13 or before.
-#define LONG_WIDTH (sizeof(long) * CHAR_BIT)
+// Use __SIZEOF_LONG__ * CHAR_BIT as backup.  This is needed for clang-13 or
+// before.
+#define LONG_WIDTH (__SIZEOF_LONG__ * CHAR_BIT)
 #endif // __LONG_WIDTH__
 #endif // LONG_WIDTH