-extern bool __wimlib_print_errors;
-extern void wimlib_error(const char *format, ...);
-# define ERROR wimlib_error
+extern void wimlib_error(const char *format, ...)
+ FORMAT(printf, 1, 2) COLD;
+extern void wimlib_error_with_errno(const char *format, ...)
+ FORMAT(printf, 1, 2) COLD;
+extern void wimlib_warning(const char *format, ...)
+ FORMAT(printf, 1, 2) COLD;
+extern void wimlib_warning_with_errno(const char *format, ...)
+ FORMAT(printf, 1, 2) COLD;
+# define ERROR wimlib_error
+# define ERROR_WITH_ERRNO wimlib_error_with_errno
+# define WARNING wimlib_warning
+# define WARNING_WITH_ERRNO wimlib_warning