GNU bug report logs - #3424
align-regexp: Infinite loop with default regexp

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From: help-debbugs <at> gnu.org (Emacs bug Tracking System)
To: Teemu Likonen <tlikonen <at> iki.fi>
Subject: bug#3424: marked as done (align-regexp: Infinite loop with
 default regexp)
Date: Sun, 14 Jun 2009 05:55:06 +0000

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Your message dated Sun, 14 Jun 2009 08:52:52 +0300
with message-id <87ljnv5pl7.fsf <at> iki.fi>
and subject line Re: align-regexp: Infinite loop with default regexp
has caused the Emacs bug report #3424,
regarding align-regexp: Infinite loop with default regexp
to be marked as done.

This means that you claim that the problem has been dealt with.
If this is not the case it is now your responsibility to reopen the
bug report if necessary, and/or fix the problem forthwith.

(NB: If you are a system administrator and have no idea what this
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-- 
3424: http://debbugs.gnu.org/cgi/bugreport.cgi?bug=3424
Emacs Bug Tracking System
Contact help-debbugs <at> gnu.org with problems

[Message part 2 (message/rfc822, inline)]

From: Teemu Likonen <tlikonen <at> iki.fi>
To: bug-gnu-emacs <at> gnu.org
Subject: align-regexp: Infinite loop with default regexp
Date: Sat, 30 May 2009 20:37:44 +0300

[Message part 3 (text/plain, inline)]

The align-regexp command enters infinite loop when it is used with the
default regexp and with REPEAT argument. It's seems to be because the
regexp \s-* matches also zero-length strings.

Steps to reproduce:

 1. Put the following line to the *scratch* buffer:

        foo bar

 2. Put the line inside a region

 3. Type command:

        C-u M-x align-regexp RET \(\s-*\) RET 1 RET 1 RET y

 4. Loop infinitely.


I suggest changing the default regexp to \(\s-+\), like the attached
patch illustrates.

[align-regexp.patch (text/x-diff, inline)]

diff --git i/lisp/align.el w/lisp/align.el
index 0917e7d..ea36302 100644
--- i/lisp/align.el
+++ w/lisp/align.el
@@ -933,7 +933,7 @@ region, call `align-regexp' and type in that regular expression."
     (list (region-beginning) (region-end))
     (if current-prefix-arg
 	(list (read-string "Complex align using regexp: "
-			   "\\(\\s-*\\)")
+			   "\\(\\s-+\\)")
 	      (string-to-number
 	       (read-string
 		"Parenthesis group to modify (justify if negative): " "1"))
@@ -941,7 +941,7 @@ region, call `align-regexp' and type in that regular expression."
 	       (read-string "Amount of spacing (or column if negative): "
 			    (number-to-string align-default-spacing)))
 	      (y-or-n-p "Repeat throughout line? "))
-      (list (concat "\\(\\s-*\\)"
+      (list (concat "\\(\\s-+\\)"
 		    (read-string "Align regexp: "))
 	    1 align-default-spacing nil))))
   (let ((rule

[Message part 5 (message/rfc822, inline)]

From: Teemu Likonen <tlikonen <at> iki.fi>
To: 3424-done <at> debbugs.gnu.org
Subject: Re: align-regexp: Infinite loop with default regexp
Date: Sun, 14 Jun 2009 08:52:52 +0300

On 2009-05-30 20:37 (+0300), Teemu Likonen wrote:

> The align-regexp command enters infinite loop when it is used with the
> default regexp and with REPEAT argument. It's seems to be because the
> regexp \s-* matches also zero-length strings.

I have misunderstood the behaviour of the regexp. The default space
group \s-* is about the spaces to modify before some other matching
regexp. It's a bit unexpected to me but I originally reported about
infinite loop which is indeed fixed in Emacs 23. So let's close this
bug.

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