* lisp/progmodes/perl-mode.el (perl-syntax-propertize-special-constructs):

Don't move backward, so as not to fall in an inf-loop.

Fixes: debbugs:7736

2 files changed, 7 insertions, 2 deletions

diff --git a/lisp/ChangeLog b/lisp/ChangeLog
index 0a2b34cb024..62aeaf7f92f 100644
--- a/lisp/ChangeLog
+++ b/lisp/ChangeLog
@@ -1,5 +1,8 @@
 2011-01-24  Stefan Monnier  <monnier@iro.umontreal.ca>
 
+        * progmodes/perl-mode.el (perl-syntax-propertize-special-constructs):
+        Don't move backward, so as not to fall in an inf-loop (bug#7736).
+
         * progmodes/ruby-mode.el (ruby-syntax-propertize-function): (bug#7735)
         Handle ?" and friends differently (e.g. don't use backrefs).
 
diff --git a/lisp/progmodes/perl-mode.el b/lisp/progmodes/perl-mode.el
index 85429ac96af..64cf2c989c2 100644
--- a/lisp/progmodes/perl-mode.el
+++ b/lisp/progmodes/perl-mode.el
@@ -360,7 +360,8 @@ The expansion is entirely correct because it uses the C preprocessor."
      (t
       ;; This is regexp like quote thingy.
       (setq char (char-after (nth 8 state)))
-      (let ((twoargs (save-excursion
+      (let ((startpos (point))
+            (twoargs (save-excursion
                        (goto-char (nth 8 state))
                        (skip-syntax-backward " ")
                        (skip-syntax-backward "w")
@@ -384,7 +385,8 @@ The expansion is entirely correct because it uses the C preprocessor."
                           (goto-char (1+ (nth 8 state)))
                           (up-list 1)
                           t)
-                      (scan-error nil))
+                      ;; In case of error, make sure we don't move backward.
+                      (scan-error (goto-char startpos) nil))
                   (not (or (nth 8 (parse-partial-sexp
                                    (point) limit nil nil state 'syntax-table))
                            ;; If we have a self-paired opener and a twoargs