The Quake III Arena sources as originally released under the GPL license on August 20, 2005.

lcc/lib/yynull.c

@@ -0,0 +1,12 @@
+#include <stdio.h>
+#include <stdlib.h>
+
+
+void _YYnull(char *file, int line) {
+	fprintf(stderr, "null pointer dereferenced:");
+	if (file)
+		fprintf(stderr, " file %s,", file);
+	fprintf(stderr, " line %d\n", line);
+	fflush(stderr);
+	abort();
+}