+
+const char *bus_error_message(const sd_bus_error *e, int error);
+
+int bus_error_setfv(sd_bus_error *e, const char *name, const char *format, va_list ap) _printf_(3,0);
+int bus_error_set_errnofv(sd_bus_error *e, int error, const char *format, va_list ap) _printf_(3,0);