[libc] Add backup definition for LONG_WIDTH in limits-macros.h.

[lntue]

No description provided.

[llvmbot]

@llvm/pr-subscribers-libc

Author: None (lntue)

Changes

---

Full diff: https://github.com/llvm/llvm-project/pull/79375.diff

1 Files Affected:

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

diff --git a/libc/include/llvm-libc-macros/limits-macros.h b/libc/include/llvm-libc-macros/limits-macros.h
index fc21d1318a081b..1926bc25bcfa1d 100644
--- a/libc/include/llvm-libc-macros/limits-macros.h
+++ b/libc/include/llvm-libc-macros/limits-macros.h
@@ -69,8 +69,8 @@
 #define LONG_WIDTH __LONG_WIDTH__
 #elif defined(__WORDSIZE)
 #define LONG_WIDTH __WORDSIZE
-#else
-#error "Unknown WORDSIZE to define LONG_WIDTH."
+#else // use sizeof(long) * CHAR_BIT as backup.
+#define LONG_WIDTH (sizeof(long) * CHAR_BIT)
 #endif // __LONG_WIDTH__
 #endif // LONG_WIDTH
 

[SchrodingerZhu]

Lgtm