-bool id_is_valid (const char *id, const char *dict_encoding, bool issue_error);
-bool id_is_plausible (const char *id, bool issue_error);
+bool id_is_valid (const char *id, const char *dict_encoding);
+bool id_is_plausible (const char *id);
+char *id_is_valid__ (const char *id, const char *dict_encoding)
+ WARN_UNUSED_RESULT;
+char *id_is_plausible__ (const char *id) WARN_UNUSED_RESULT;