clang supports __builtin_expect, even on Windows.
Most Gnulib modules use the 'builtin-expect' module with its Autoconf test,
however, some use the macros from lib/cdefs.h.
2020-08-06 Bruno Haible <br...@clisp.org>
Use __builtin_expect with clang everywhere.
* lib/cdefs.h (__glibc_unlikely, __glibc_likely): Use the GCC built-in
also on clang.
diff --git a/lib/cdefs.h b/lib/cdefs.h
index 2158379..b034c0b 100644
--- a/lib/cdefs.h
+++ b/lib/cdefs.h
@@ -401,7 +401,7 @@
# endif
#endif
-#if __GNUC__ >= 3
+#if (__GNUC__ >= 3) || (__clang_major__ >= 4)
# define __glibc_unlikely(cond) __builtin_expect ((cond), 0)
# define __glibc_likely(cond) __builtin_expect ((cond), 1)
#else
