GNU bug report logs - #4356
23.1.50; expand-abbrev changes point erroneously

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Message #5 received at submit <at> emacsbugs.donarmstrong.com (full text, mbox):

From: Vincent Belaïche <vincent.b.1 <at> hotmail.fr>
To: emacs-pretest-bug <at> gnu.org
Subject: 23.1.50; expand-abbrev changes point erroneously
Date: Sun, 06 Sep 2009 12:30:26 +0200

Here is the bug description. I found this editing some Visual Basic file
 with using http://www.emacswiki.org/emacs/visual-basic-mode.el

If for instance I type <RET> after (--!-- showing point when I type <RET>):

MyVar = MyFun(1,True)--!--


Then in visual basic mode visual-basic-newline-and-indent is called,
which in turn calls (expand-abbrev). After (expand-abbrev) is called,
point will be moved as follows: 

MyVar = MyFun(1,True--!--) 

because `True' is one abbreviation. I have patched visual-basic mode, so
that a save-excursion encloses the call of expand-abbrev, otherwise I
would get:

MyVar = MyFun(1,True
--!--) 

which is not wanted. Stefan Monnier (monnier <at> IRO.UMontreal.CA) confirmed
this is a bug of expand-abbrev, and asked me to repport it.

The wanted behaviour would be that after expanding `True', point would
come back to after the `)' where it originally was.

BR,
   Vincent.


-----------------------------------------------------------------------


If Emacs crashed, and you have the Emacs process in the gdb debugger,
please include the output from the following gdb commands:
    `bt full' and `xbacktrace'.
If you would like to further debug the crash, please read the file
d:/Programme/GNU/Emacs/etc/DEBUG for instructions.


In GNU Emacs 23.1.50.1 (i386-mingw-nt5.0.2195)
 of 2009-07-25 on COCOTTE
Windowing system distributor `Microsoft Corp.', version 5.0.2195
configured using `configure --with-gcc (3.4)'

Important settings:
  value of $LC_ALL: nil
  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: FRA
  value of $XMODIFIERS: nil
  locale-coding-system: cp1252
  default-enable-multibyte-characters: t

Major mode: Lisp Interaction

Minor modes in effect:
  recentf-mode: t
  mail-abbrevs-mode: t
  iswitchb-mode: t
  tooltip-mode: t
  mouse-wheel-mode: t
  menu-bar-mode: t
  file-name-shadow-mode: t
  global-font-lock-mode: t
  font-lock-mode: t
  blink-cursor-mode: t
  global-auto-composition-mode: t
  auto-composition-mode: t
  auto-encryption-mode: t
  auto-compression-mode: t
  line-number-mode: t
  transient-mark-mode: t

Recent input:
<left> <return> C-x 1 <down> <down> C-SPC <end> <left> 
<C-insert> C-x b * s c <tab> ( r e q u i r e SPC ' 
c a l c - e x t ) <return> ( l a t SPC ( <backspace> 
<backspace> <backspace> <backspace> e t SPC ( c a l 
c - c o m m a n d ) <C-left> <C-left> C-h f C-g C-h 
v c a l c - c <tab> o <tab> <backspace> <backspace> 
<backspace> <tab> <backspace> <backspace> <backspace> 
<backspace> <backspace> C-g <end> <return> <tab> ( 
c a l c - r a d i x SPC 1 <backspace> 7 ) <return> 
<tab> ( c a l c - e v a l SPC 1 0 à ) <backspace> <backspace> 
) <left> <left> <left> " " SPC <left> <left> $ <end> 
) M-x e v a l - b u f <tab> <return> C-x C-e <C-left> 
<C-left> <C-left> C-h f <return> C-h i m d <backspace> 
c a l <tab> <return> C-x 1 <C-end> <up> <up> <up> <up> 
<up> <up> <right> <right> <right> <down> <return> C-s 
c a l c <kp-subtract> e v <C-end> <up> <C-home> m e 
v a l <return> C-x b <return> <end> <C-left> <C-left> 
<C-right> <right> <right> <delete> <kp-1> <kp-0> <right> 
<delete> <delete> <delete> <end> C-x C-e <up> <up> 
<up> <down> <up> <return> C-y <up> <home> C-k C-k <down> 
<up> <tab> <down> C-k C-k C-k C-k <tab> <end> <backspace> 
<home> ( m e s s a g z e SPC <backspace> <backspace> 
<backspace> e SPC " 1 0 SPC e n SPC b a s e SPC 7 = 
% s " SPC <end> ) M-x <up> <return> <up> <up> <home> 
C-SPC <C-end> <C-insert> <help-echo> M-x r e p o r 
<tab> b <tab> <tab> e m <tab> <return>

Recent messages:
Composing main Info directory...done
Mark set
Mark saved where search started
Mark set [2 times]
Number radix is 7
"7#13"
Mark set
10 en base 7=7#13
Mark set
Making completion list...

Load-path shadows:
d:/Programme/GNU/emacs-extension/cedet/speedbar/speedbar hides d:/Programme/GNU/Emacs/lisp/speedbar
d:/Programme/GNU/emacs-extension/cedet/speedbar/sb-image hides d:/Programme/GNU/Emacs/lisp/sb-image
d:/Programme/GNU/emacs-extension/cedet/common/ezimage hides d:/Programme/GNU/Emacs/lisp/ezimage
d:/Programme/GNU/emacs-extension/cedet/speedbar/dframe hides d:/Programme/GNU/Emacs/lisp/dframe
c:/Documents and Settings/Vincent/Application Data/.emacs.d/etc/custom hides d:/Programme/GNU/Emacs/lisp/custom

Message #10 received at 4356 <at> emacsbugs.donarmstrong.com (full text, mbox):

From: Stefan Monnier <monnier <at> iro.umontreal.ca>
To: Vincent Belaïche <vincent.b.1 <at> hotmail.fr>
Cc: 4356 <at> debbugs.gnu.org
Subject: Re: bug#4356: 23.1.50; expand-abbrev changes point erroneously
Date: Tue, 15 Sep 2009 22:46:00 -0400

> Here is the bug description. I found this editing some Visual Basic file
> with using http://www.emacswiki.org/emacs/visual-basic-mode.el

> If for instance I type <RET> after (--!-- showing point when I type <RET>):

> MyVar = MyFun(1,True)--!--

> Then in visual basic mode visual-basic-newline-and-indent is called,
> which in turn calls (expand-abbrev).  After (expand-abbrev) is called,
> point will be moved as follows: 

> MyVar = MyFun(1,True--!--) 

> because `True' is one abbreviation.  I have patched visual-basic mode, so
> that a save-excursion encloses the call of expand-abbrev, otherwise I
> would get:

> MyVar = MyFun(1,True
> --!--) 

> which is not wanted. Stefan Monnier (monnier <at> IRO.UMontreal.CA) confirmed
> this is a bug of expand-abbrev, and asked me to repport it.

> The wanted behaviour would be that after expanding `True', point would
> come back to after the `)' where it originally was.

Having looked into it some more, I'm not 100% convinced it's a bug
any more.  Here's why:

`expand-abbrev' may run arbitrary code, and some abbrevs don't just
replace text with something else but also prompt and/or move point
(e.g. skeletons).  So running expand-abbrev from
visual-basic-newline-and-indent just doesn't sound right since it may
conflict with user-defined abbreviations.

I.e. the problem you're seeing can also happen in Emacs-22 depending on
the user's own abbreviations.  So the VBM code either needs
a save-excursion, or needs to refrain from calling expand-abbrev from
visual-basic-newline-and-indent.


        Stefan

Message #17 received at 4356-done <at> debbugs.gnu.org (full text, mbox):

From: Glenn Morris <rgm <at> gnu.org>
To: 4356-done <at> debbugs.gnu.org
Subject: Re: bug#4356: 23.1.50; expand-abbrev changes point erroneously
Date: Wed, 05 Oct 2011 23:52:54 -0400

tags 4356 wontfix
stop

Closing based on this:

> Having looked into it some more, I'm not 100% convinced it's a bug
> any more.  Here's why:
>
> `expand-abbrev' may run arbitrary code, and some abbrevs don't just
> replace text with something else but also prompt and/or move point
> (e.g. skeletons).  So running expand-abbrev from
> visual-basic-newline-and-indent just doesn't sound right since it may
> conflict with user-defined abbreviations.
>
> I.e. the problem you're seeing can also happen in Emacs-22 depending on
> the user's own abbreviations.  So the VBM code either needs
> a save-excursion, or needs to refrain from calling expand-abbrev from
> visual-basic-newline-and-indent.

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