GNU bug report logs - #13438
24.2.92; Infinite loop in python imenu support

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Package: emacs;

Reported by: Ivan Andrus <darthandrus <at> gmail.com>

Date: Mon, 14 Jan 2013 21:00:02 UTC

Severity: important

Found in version 24.2.92

Done: Fabián Ezequiel Gallina <fabian <at> anue.biz>

Bug is archived. No further changes may be made.

Full log

Message #28 received at 13438 <at> debbugs.gnu.org (full text, mbox):

From: Glenn Morris <rgm <at> gnu.org>
To: Fabián Ezequiel Gallina <fabian <at> anue.biz>
Cc: 13438 <at> debbugs.gnu.org, Stefan Monnier <monnier <at> iro.umontreal.ca>
Subject: Re: bug#13438: /srv/bzr/emacs/emacs-24 r111196: * imenu.el
	(imenu-default-create-index-function): Remove useless
Date: Sat, 26 Jan 2013 21:12:50 -0500

Oh, so the actual issue is: if you call
imenu-default-create-index-function with point at the start of the last
defun in the buffer. It goes to point-max, then back to the start of the
defun, and mistakenly thinks it is inflooping.

How about the following, which only signals an error if
imenu-prev-index-position-function returns non-nil twice in a row
without moving point.

BTW, neither python-nav-beginning-of-defun or
python-imenu-prev-index-position will move past the start of the first
defun in a buffer, if the defun begins past point-min (ie, if there are
blank lines before the first defun, it does not move over them to
point-min). I don't know if this matters, but it is inconsistent with eg
Prolog and Emacs Lisp modes.


*** lisp/imenu.el	2013-01-23 21:55:46 +0000
--- lisp/imenu.el	2013-01-27 02:02:39 +0000
***************
*** 678,688 ****
    ;; in these major modes.  But save that change for later.
    (cond ((and imenu-prev-index-position-function
  	      imenu-extract-index-name-function)
! 	 (let ((index-alist '()) (pos (point))
  	       name)
  	   (goto-char (point-max))
  	   ;; Search for the function
  	   (while (funcall imenu-prev-index-position-function)
               (setq pos (point))
  	     (save-excursion
  	       (setq name (funcall imenu-extract-index-name-function)))
--- 678,690 ----
    ;; in these major modes.  But save that change for later.
    (cond ((and imenu-prev-index-position-function
  	      imenu-extract-index-name-function)
! 	 (let ((index-alist '()) (pos -1)
  	       name)
  	   (goto-char (point-max))
  	   ;; Search for the function
  	   (while (funcall imenu-prev-index-position-function)
+              (when (= pos (point))
+                (error "Infinite loop at %s:%d: imenu-prev-index-position-function does not move point" (buffer-name) pos))
               (setq pos (point))
  	     (save-excursion
  	       (setq name (funcall imenu-extract-index-name-function)))
This bug report was last modified 12 years and 118 days ago.

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