__printflike
...) __printflike(3, 4);
__va_list) __printflike(3, 0);
int asprintf(char **, const char *, ...) __printflike(2, 3);
__printflike(2, 0);
extern int printf(const char *fmt, ...) __printflike(1, 2);
extern int asprintf(char **buf, const char *cfmt, ...) __printflike(2, 3);
extern int sprintf(char *buf, const char *cfmt, ...) __printflike(2, 3);
__printflike(3, 4);
extern void panic(const char *, ...) __dead2 __printflike(1, 2);