Fix XXH_HAS_C_ATTRIBUTE check

diff --git a/include/xxhash.h b/include/xxhash.h
index fbd1aab9aca03eff09f65e19a10003953c58bbba..c17521f99f37b426be80dc656e77ac7ddbd65a03 100644 (file)
--- a/include/xxhash.h
+++ b/include/xxhash.h
@@ -631,14 +631,12 @@ introduced in CPP17 and C23.
 CPP17 : https://en.cppreference.com/w/cpp/language/attributes/fallthrough
 C23   : https://en.cppreference.com/w/c/language/attributes/fallthrough
 */
-#if XXH_HAS_C_ATTRIBUTE(x)
-# define XXH_FALLTHROUGH [[fallthrough]]
-#elif XXH_HAS_CPP_ATTRIBUTE(x)
+#if XXH_HAS_C_ATTRIBUTE(fallthrough) || XXH_HAS_CPP_ATTRIBUTE(fallthrough)
 # define XXH_FALLTHROUGH [[fallthrough]]
 #elif XXH_HAS_ATTRIBUTE(__fallthrough__)
-# define XXH_FALLTHROUGH __attribute__ ((fallthrough))
+# define XXH_FALLTHROUGH __attribute__ ((__fallthrough__))
 #else
-# define XXH_FALLTHROUGH
+# define XXH_FALLTHROUGH /* fallthrough */
 #endif
 
 /*!