#define PURE_FUNCTION
#endif
+/* This attribute indicates that the argument with the given
+ IDX must be a null pointer. IDX counts backward in the
+ argument list, so that 0 is the last argument, 1 is the
+ second-from-last argument, and so on. */
+#if __GNUC__ > 3
+#define SENTINEL(IDX) ATTRIBUTE ((sentinel(IDX)))
+#else
+#define SENTINEL
+#endif
+
#endif /* compiler.h */