regex bug with pattern "\\*/" matching end of buffer */

regex bug with pattern "\\*/" matching end of buffer */

[Geoff Odhner]

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In GNU Emacs 21.3.1 (i686-pc-linux-gnu, X toolkit)
 of 2005-03-24 on monster
configured using `configure  --prefix=/home/geoff/i686 --with-toolkit-scroll-bars'
Important settings:
  value of $LC_ALL: C
  value of $LC_COLLATE: nil
  value of $LC_CTYPE: nil
  value of $LC_MESSAGES: nil
  value of $LC_MONETARY: nil
  value of $LC_NUMERIC: nil
  value of $LC_TIME: nil
  value of $LANG: en_US.UTF-8
  locale-coding-system: nil
  default-enable-multibyte-characters: t

Please describe exactly what actions triggered the bug
and the precise symptoms of the bug:

If I have a file with the following line (no trailing space):

	char	ch;	/* sample comment */

then I put the cursor on it and execute the following elisp code:

	(save-restriction
	  (narrow-to-region (progn (beginning-of-line) (point))
			    (progn (end-of-line) (point)))
	  (goto-char (point-min))
	  (while (and (re-search-forward "/\\*"  nil t) (not (eobp)))
	    (replace-match "/-*" nil nil))
	  (goto-char (point-min))
	  (while (and (re-search-forward "\\*/"  nil t) (not (eobp)))
	    (replace-match "*-/" nil nil)))

it will give me the following line as the result:

	char	ch;	/-* sample comment */

In contrast, what I expect is this:

	char	ch;	/-* sample comment *-/

If I add a trailing space, then I get appropriate behavior.


Regards,

Geoff Odhner



Recent input:
<backspace> <backspace> <backspace> <backspace> <backspace> 
<backspace> <backspace> <backspace> <backspace> <backspace> 
<backspace> r e p l <tab> s t <tab> <return> C-x 0 
<help-echo> <switch-frame> <down-mouse-1> <mouse-movement> 
<mouse-1> <kp-subtract> <up> <kp-add> A-s <f2> <up> 
<up> <up> <return> <up> <up> <return> <f10> <f2> w 
i d <tab> e <tab> <return> <C-kp-add> A-z <f2> k <return> 
<f2> r e l SPC <return> <f3> <S-kp-add> A-z C-x C-v 
<return> <next> <next> <next> <down-mouse-1> <mouse-1> 
<C-kp-add> A-z <down-mouse-1> <mouse-1> <kp-subtract> 
<down> <kp-add> A-z <up> A-z A-s <down-mouse-1> <mouse-1> 
<down-mouse-1> <mouse-1> <down-mouse-1> <mouse-1> SPC 
<S-kp-add> A-z A-z <help-echo> <help-echo> <help-echo> 
<help-echo> <help-echo> <help-echo> <menu-bar> <help-menu> 
<report-emacs-bug>

Recent messages:

Undo!
Mark set [2 times]
Line eaten
Mark set [2 times]
Line inserted
Undo! [2 times]
Wrote /home/geoff/ggoo/elisp/el/lines-G.el
Undo! [2 times]
Loading emacsbug...done

Re: regex bug with pattern "\\*/" matching end of buffer */

[Geoff Odhner]

Thank you.  I am relieved to find the bug is in my code.  Indeed, it works 
correctly when I recode it thus:
         (while (and (re-search-forward "\\*/"  nil t) (replace-match 
"*-/" nil nil)) (not (eobp))))

Geoff Odhner


Richard Stallman <rms@gnu.org> wrote on 04/30/2005 07:18:50 PM:

>          (while (and (re-search-forward "\\*/"  nil t) (not (eobp)))
>       (replace-match "*-/" nil nil)))
> 
>     it will give me the following line as the result:
> 
>        char   ch;   /-* sample comment */
> 
> That's because (eobp) returns t when you're at the end of the
> accessible portion of the buffer.  So the bug is in your code,
> I think.
>