On 01/25/2013 05:34 AM, Glenn Morris wrote:

      

        

          
Why is this issue (apparently) only seen in Python mode


        

      

      
Answering my own question, it happens in any mode that sets
imenu-prev-index-position-function and
imenu-extract-index-name-function, but there are very few of those.

Eg prolog mode. With buffer contents:

------
fac(0,1).
fac(N,F) :- N > 0, M is N - 1,
       fac(M,Fm), F is N * Fm.
------

and point at point-min, switching to prolog-mode causes the same issue.

How about taking the more cautious approach with:

(when (and (= pos (point))
           (not (bobp)))
   (error "Infinite loop... ))

(IIUC, this was actually the suggestion in
http://lists.gnu.org/archive/html/emacs-devel/2013-01/msg00510.html ?)


    

    I ran into the same thing, and checking bobp is not enough, try
    adding a newline at the beginning of file to the recipe and call
    imenu with point at beginning of defun and you'll see the infinite
    error check will trigger.

    

    I proposed the following patch that works:

    

    === modified file 'lisp/imenu.el'

    --- lisp/imenu.el       2013-01-01 09:11:05 +0000

    +++ lisp/imenu.el       2013-01-22 18:24:45 +0000

    @@ -683,7 +683,14 @@

    
           (goto-char (point-max))

                 ;; Search for the function

                 (while (funcall imenu-prev-index-position-function)

      -             (when (= pos (point))

      +             (when (and (= pos (point))

    

    +                        (= pos

    +                           (save-excursion

    +                             ;; The infinite loop is true if
    there's

    +                             ;; another index position but point
    keeps

    +                             ;; itself in the same place. bug#13438

    +                             (if (funcall
    imenu-prev-index-position-
    
function)

      +                                 (point) 0))))

    

    But finally after some mails with Stefan we decided the best thing
    will be to remove this check altogether.