(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.

diff --git a/lisp/progmodes/cc-engine.el b/lisp/progmodes/cc-engine.el
index 58d61eb218218ab427cc0b745213b23a5446c531..c2be72b00431c76f81b3eabb5681dfc83586be16 100644 (file)
--- 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"