diff '--color=auto' --unified --recursive --text cc0.r771/lib/cc0main.c cc0.r771.new/lib/cc0main.c
--- cc0.r771/lib/cc0main.c	2021-01-12 12:20:49.000000000 -0500
+++ cc0.r771.new/lib/cc0main.c	2021-07-01 19:56:59.398515215 -0400
@@ -16,8 +16,8 @@
 char **c0_argv;
 
 // Defined externally by CC0
-long map_length;
-const char* source_map[0];
+extern long map_length;
+extern const char* source_map[0];
 
 FILE *really_fopen(const char *filename, const char *mode,
                    char *error)