extern int git_diff_basic_config(const char *var, const char *value, void *cb);
extern int git_diff_ui_config(const char *var, const char *value, void *cb);
-extern int diff_use_color_default;
extern void diff_setup(struct diff_options *);
extern int diff_opt_parse(struct diff_options *, const char **, int);
extern void diff_setup_done(struct diff_options *);