+#define RE_NO_POSIX_BACKTRACKING (RE_NO_EMPTY_RANGES << 1)
+
+/* If this bit is set, then (?:...) is treated as a shy group. */
+#define RE_SHY_GROUPS (RE_NO_POSIX_BACKTRACKING << 1)
+
+/* If this bit is set, then an unmatched ) is ordinary.
+ If not set, then an unmatched ) is invalid. */
+#define RE_UNMATCHED_RIGHT_PAREN_ORD (RE_SHY_GROUPS << 1)