GNU bug report logs - #7044
24.0.50; Emacs crashes after calling ediff-regions-linewise

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Message #5 received at submit <at> debbugs.gnu.org (full text, mbox):

From: Stephen Berman <stephen.berman <at> gmx.net>
To: bug-gnu-emacs <at> gnu.org
Subject: 24.0.50; Emacs crashes after calling ediff-regions-linewise
Date: Thu, 16 Sep 2010 19:28:54 +0200

[Message part 1 (text/plain, inline)]

1. emacs -Q
2. M-x ediff-regions-linewise, type RET twice to use *scratch* for both
   Ediff buffers (it doesn't matter which buffers are used).
3. Any attempt to mark a region, indeed it seems any further input at
   all, makes Emacs abort.  This is completely reproducible. Full
   backtrace attached. 

In GNU Emacs 24.0.50.7 (i686-pc-linux-gnu, GTK+ Version 2.18.6)
 of 2010-09-16 on escher
Windowing system distributor `The X.Org Foundation', version 11.0.10605000
configured using `configure  '--with-imagemagick' '--without-toolkit-scroll-bars''

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: en_US.UTF-8
  value of $XMODIFIERS: @im=local
  locale-coding-system: utf-8-unix
  default enable-multibyte-characters: t

[Message part 2 (text/plain, attachment)]

Message #8 received at 7044 <at> debbugs.gnu.org (full text, mbox):

From: Juanma Barranquero <lekktu <at> gmail.com>
To: Stephen Berman <stephen.berman <at> gmx.net>
Cc: 7044 <at> debbugs.gnu.org
Subject: Re: bug#7044: 24.0.50;
	Emacs crashes after calling ediff-regions-linewise
Date: Sun, 26 Sep 2010 01:41:39 +0200

> 1. emacs -Q
> 2. M-x ediff-regions-linewise, type RET twice to use *scratch* for both
>   Ediff buffers (it doesn't matter which buffers are used).
> 3. Any attempt to mark a region, indeed it seems any further input at
>   all, makes Emacs abort.  This is completely reproducible. Full
>   backtrace attached.

On keyboard.c:command_loop, line 1789,

  current_buffer->mark_active => t
  Vtransient_mark_mode => t
  Vdeactivate_mark => nil
  Vselect_active_regions => t

When line 1814 is reached, current_buffer->mark contains a marker that
points to no buffer

  (gdb) p current_buffer->mark
  $8 = 48498715
  (gdb) pr
  #<marker in no buffer>

so

  Fmarker_position (current_buffer->mark)

returns nil, and so beg is assigned XINT (nil), which is a bug.

Now, shouldn't current_buffer->mark_active be nil if the mark points nowhere?

    Juanma

Message #11 received at 7044 <at> debbugs.gnu.org (full text, mbox):

From: Chong Yidong <cyd <at> stupidchicken.com>
To: Juanma Barranquero <lekktu <at> gmail.com>
Cc: Stephen Berman <stephen.berman <at> gmx.net>, 7044 <at> debbugs.gnu.org
Subject: Re: bug#7044: 24.0.50;
	Emacs crashes after calling ediff-regions-linewise
Date: Sat, 02 Oct 2010 21:00:06 -0400

Juanma Barranquero <lekktu <at> gmail.com> writes:

>   Fmarker_position (current_buffer->mark)
>
> returns nil, and so beg is assigned XINT (nil), which is a bug.
>
> Now, shouldn't current_buffer->mark_active be nil if the mark points
> nowhere?

No; it's possible that the buffer-local variable mark-active has been
set but the actual marker hasn't been assigned yet.  This was an
oversight on my part, and I've now checked in a fix.

Thanks.

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