-extern void warn (const char *format, ...)
- __attribute__ ((__format__ (__printf__, 1, 2)));
+void warn (const char *format, ...)
+ __attribute__ ((__format__ (__printf__, 1, 2)));
+
+void warn_at (location_t location, const char *format, ...)
+ __attribute__ ((__format__ (__printf__, 2, 3)));