Add format attribute to printf like functions

deps/yopt.h

@@ -113,7 +113,9 @@ static inline const yopt_opt_t *_yopt_find(const yopt_opt_t *o, const char *v) {
 	return NULL;
 }
 
-
+#ifdef __GNUC__
+__attribute__((format(printf,3,4)))
+#endif
 static inline int _yopt_err(yopt_t *o, char **val, const char *fmt, ...) {
 	va_list va;
 	va_start(va, fmt);

src/dir.h

@@ -128,6 +128,9 @@ void dir_setlasterr(const char *);
 
 /* Error message on fatal error, or NULL if there hasn't been a fatal error yet. */
 extern char *dir_fatalerr;
+#ifdef __GNUC__
+__attribute__((format(printf,1,2)))
+#endif
 void dir_seterr(const char *, ...);
 
 extern int dir_ui;

src/util.h

@@ -106,6 +106,9 @@ int ncresize(int, int);
 void nccreate(int, int, const char *);
 
 /* printf something somewhere in the last created window */
+#ifdef __GNUC__
+__attribute__((format(printf,3,4)))
+#endif
 void ncprint(int, int, const char *, ...);
 
 /* Add a "tab" to a window */