(c-parse-state): Added kludge to avoid an infinite loop when Emacs'

open-paren-in-column-zero rule kicks in and causes the sexp functions
to misbehave.

1 files changed, 10 insertions, 3 deletions

diff --git a/lisp/progmodes/cc-engine.el b/lisp/progmodes/cc-engine.el
index 58d61eb2182..c2be72b0043 100644
--- a/lisp/progmodes/cc-engine.el
+++ b/lisp/progmodes/cc-engine.el
@@ -1144,7 +1144,7 @@ you need both the type of a literal and its limits."
     (let* ((here (point))
            (c-macro-start (c-query-macro-start))
            (in-macro-start (or c-macro-start (point)))
-           old-state last-pos pairs pos)
+           old-state last-pos pairs pos save-pos)
       ;; Somewhat ugly use of c-check-state-cache to get rid of the
       ;; part of the state cache that is after point.  Can't use
       ;; c-whack-state-after for the same reasons as in that function.
@@ -1225,7 +1225,8 @@ you need both the type of a literal and its limits."
       (narrow-to-region (point-min) here)
       (while pos
         ;; Find the balanced brace pairs.
-        (setq pairs nil)
+        (setq save-pos pos
+              pairs nil)
         (while (and (setq last-pos (c-down-list-forward pos))
                     (setq pos (c-up-list-forward last-pos)))
           (if (eq (char-before last-pos) ?{)
@@ -1269,7 +1270,13 @@ you need both the type of a literal and its limits."
               (progn
                 (setq pos (c-up-list-backward pos)
                       c-state-cache nil)
-                (unless pos
+                (when (or (not pos)
+                          ;; Emacs (up to at least 21.2) can get confused by
+                          ;; open parens in column zero inside comments: The
+                          ;; sexp functions can then misbehave and bring us
+                          ;; back to the same point again.  Check this so that
+                          ;; we don't get an infinite loop.
+                          (>= pos save-pos))
                   (setq pos last-pos
                         c-parsing-error
                         (format "Unbalanced close paren at line %d"