[W.I.P] ext/mbstring: Add some TODO

Author: Girgias

ext/mbstring/mbstring.c

@@ -538,6 +538,7 @@ static void _php_mb_free_regex(void *opaque)
 }
 /* }}} */
 
+// TODO make void as return value is ignored?
 /* {{{ php_mb_nls_get_default_detect_order_list */
 static int php_mb_nls_get_default_detect_order_list(enum mbfl_no_language lang, enum mbfl_no_encoding **plist, size_t *plist_size)
 {
@@ -858,6 +859,7 @@ static PHP_INI_MH(OnUpdate_mbstring_substitute_character)
 					MBSTRG(filter_illegal_substchar) = c;
 					MBSTRG(current_filter_illegal_substchar) = c;
 				}
+				// TODO Warn about invalid character?
 			}
 		}
 	} else {