(font-lock-fontify-keywords-region): Avoid inf-loops

when the matched text is empty.

1 files changed, 5 insertions, 1 deletions

diff --git a/lisp/font-lock.el b/lisp/font-lock.el
index a1b30292e61..0a97be141df 100644
--- a/lisp/font-lock.el
+++ b/lisp/font-lock.el
@@ -1473,7 +1473,11 @@ LOUDLY, if non-nil, allows progress-meter bar."
       (while (and (< (point) end)
                   (if (stringp matcher)
                       (re-search-forward matcher end t)
-                    (funcall matcher end)))
+                    (funcall matcher end))
+                  ;; Beware empty string matches since they will
+                  ;; loop indefinitely.
+                  (or (> (point) (match-beginning 0))
+                      (progn (forward-char 1) t)))
         (when (and font-lock-multiline
                    (>= (point)
                        (save-excursion (goto-char (match-beginning 0))