+ (not (or (eq (char-before end)
+ ;; This can give nil.
+ (cdr (syntax-after beg)))
+ (eq (char-after beg)
+ ;; This can give nil.
+ (cdr (syntax-after (1- end))))
+ ;; The cdr might hold a new paren-class
+ ;; info rather than a matching-char info,
+ ;; in which case the two CDRs should match.
+ (eq (cdr (syntax-after (1- end)))
+ (cdr (syntax-after beg))))))))))))