-   last copied.  */
-#ifdef __USE_GNU
-# if !defined _HAVE_STRING_ARCH_mempcpy || defined _FORCE_INLINES
-#  ifndef _HAVE_STRING_ARCH_mempcpy
-#   if __GNUC_PREREQ (3, 4)
-#    define __mempcpy(dest, src, n) __builtin_mempcpy (dest, src, n)
-#   elif __GNUC_PREREQ (3, 0)
-#    define __mempcpy(dest, src, n) \
-  (__extension__ (__builtin_constant_p (src) && __builtin_constant_p (n)      \

@@ -320,7 +320,7 @@

 /* GCC 4.3 and above with -std=c99 or -std=gnu99 implements ISO C99
    inline semantics, unless -fgnu89-inline is used.  */
-#if (!defined __cplusplus || __GNUC_PREREQ (4,3)) && defined __GNUC__
+#if (!defined __cplusplus || __GNUC_PREREQ (4,3) || defined __clang__) && defined __GNUC__
 # if defined __GNUC_STDC_INLINE__ || defined __cplusplus
 #  define __extern_inline extern __inline __attribute__ ((__gnu_inline__))

index d1cb3dd..30482a1 100644
--- a/misc/sys/cdefs.h
+++ b/misc/sys/cdefs.h
@@ -423,4 +423,14 @@
 # endif
 #endif
 
+/* Undefine (also defined in libc-symbols.h).  */
+#undef __attribute_copy__
+#if __GNUC_PREREQ (9, 0)
+/* Copies attributes from the declaration or type referenced by
+   the argument.  */
+# define __attribute_copy__(arg) __attribute__ ((__copy__ (arg)))
+#else
+# define __attribute_copy__(arg)
+#endif