[Emacs-diffs] emacs-25 14060a9: Avoid inflooping in thing-at-point-looking-at

[Eli Zaretskii]

branch: emacs-25
commit 14060a9c1679174b37bba7140c6b715d90502d70
Author: Eli Zaretskii <address@hidden>
Commit: Eli Zaretskii <address@hidden>

    Avoid inflooping in thing-at-point-looking-at
    
    * lisp/thingatpt.el (thing-at-point-looking-at): Avoid inflooping
    with regular expressions whose matching doesn't move point.
    (Bug#22756)
    Describe the argument DISTANCE in the doc string.
---
 lisp/thingatpt.el |   13 ++++++++++---
 1 files changed, 10 insertions(+), 3 deletions(-)

diff --git a/lisp/thingatpt.el b/lisp/thingatpt.el
index 1686c02..9920fa0 100644
--- a/lisp/thingatpt.el
+++ b/lisp/thingatpt.el
@@ -489,19 +489,26 @@ looks like an email address, \"ftp://\"; if it starts with
 (defun thing-at-point-looking-at (regexp &optional distance)
   "Return non-nil if point is in or just after a match for REGEXP.
 Set the match data from the earliest such match ending at or after
-point."
+point.
+
+Optional argument DISTANCE limits search for REGEXP forward and
+back from point."
   (save-excursion
     (let ((old-point (point))
          (forward-bound (and distance (+ (point) distance)))
          (backward-bound (and distance (- (point) distance)))
-         match)
+         match prev-pos new-pos)
       (and (looking-at regexp)
           (>= (match-end 0) old-point)
           (setq match (point)))
       ;; Search back repeatedly from end of next match.
       ;; This may fail if next match ends before this match does.
       (re-search-forward regexp forward-bound 'limit)
-      (while (and (re-search-backward regexp backward-bound t)
+      (setq prev-pos (point))
+      (while (and (setq new-pos (re-search-backward regexp backward-bound t))
+                  ;; Avoid inflooping with some regexps, such as "^",
+                  ;; matching which never moves point.
+                  (< new-pos prev-pos)
                  (or (> (match-beginning 0) old-point)
                      (and (looking-at regexp)  ; Extend match-end past search 
start
                           (>= (match-end 0) old-point)