[core] __attribute__((format ...))
#endif
#endif
+#ifndef __attribute_fallthrough__
#if __has_attribute(fallthrough) \
|| __GNUC_PREREQ(7,0)
#define __attribute_fallthrough__ __attribute__((__fallthrough__));
#else
-#define __attribute_fallthrough__
+#define __attribute_fallthrough__ /* fall through */
+#endif
+#endif
+
+#ifndef __attribute_format__
+#if __has_attribute(format) \
+ || __GNUC_PREREQ(2,95) /*(maybe earlier gcc, too)*/
+#define __attribute_format__(x) __attribute__((__format__ x))
+#else
+#define __attribute_format__(x)
+#endif
#endif
