Make CC Mode not hang when _some_ lines end in CRLF. Bug #11841.

cc-engine.el (c-backward-comments): Add code to work around
`forward-comment' not recognizing ^M as whitespace.

2 files changed, 21 insertions, 2 deletions

diff --git a/lisp/ChangeLog b/lisp/ChangeLog
index c77cc286c76..fb75b3678c7 100644
--- a/lisp/ChangeLog
+++ b/lisp/ChangeLog
@@ -1,3 +1,9 @@
+2012-12-11  Alan Mackenzie  <acm@muc.de>
+
+        Make CC Mode not hang when _some_ lines end in CRLF.  Bug #11841.
+        * progmodes/cc-engine.el (c-backward-comments): Add code to work
+        around `forward-comment' not recognizing ^M as whitespace.
+
 2012-12-11  Fabián Ezequiel Gallina  <fgallina@cuca>
 
         * progmodes/python.el (python-skeleton-class)
diff --git a/lisp/progmodes/cc-engine.el b/lisp/progmodes/cc-engine.el
index 10355451480..f7248e2d2d3 100644
--- a/lisp/progmodes/cc-engine.el
+++ b/lisp/progmodes/cc-engine.el
@@ -1452,8 +1452,21 @@ comment at the start of cc-engine.el for more info."
             ;; return t when moving backwards at bob.
             (not (bobp))
 
-            (if (let (open-paren-in-column-0-is-defun-start)
-                  (forward-comment -1))
+            (if (let (open-paren-in-column-0-is-defun-start moved-comment)
+                  (while
+                      (and (not (setq moved-comment (forward-comment -1)))
+                      ;; Cope specifically with ^M^J here -
+                      ;; forward-comment sometimes gets stuck after ^Ms,
+                      ;; sometimes after ^M^J.
+                           (or
+                            (when (eq (char-before) ?\r)
+                              (backward-char)
+                              t)
+                            (when (and (eq (char-before) ?\n)
+                                       (eq (char-before (1- (point))) ?\r))
+                              (backward-char 2)
+                              t))))
+                  moved-comment)
                 (if (looking-at "\\*/")
                     ;; Emacs <= 20 and XEmacs move back over the
                     ;; closer of a block comment that lacks an opener.