Subject: bug#18153: segfault on C-e/End in Ack-and-a-half

From: Eli Zaretskii <[email-masked]>
Date: Thu, 31 Jul 2014 07:32:38 +0300

> Date: Wed, 30 Jul 2014 15:42:16 -0500
> From: Andrew Pennebaker <[email-masked]>
> 
> I enjoy using the ack-and-a-half plugin to search for text in my
> projects. Sometimes, when I try to navigate to the end of one of the
> results lines, Emacs segfaults.
> 
> This happens whether I press the C-e hotkey, or the End key on my
> keyboard.
> 
> I've only seen this segfault occur in Ack-and-a-half result buffers;
> C-e/End work find elsewhere in my Emacs workflow.

Thank you for your report.

> For reference, I use the following Emacs configuration:
> 
> https://github.com/mcandre/dotfiles/blob/master/.emacs

That .emacs file is more than 600 lines long.

> I've created an issue at the ack-and-a-half plugin website, in case anyone
> would like to contact the plugin maintainer for help troubleshooting this
> problem.
> 
> https://github.com/jhelwig/ack-and-a-half/issues/39

That issue doesn't include any information beyond what you mentioned
in this bug report.  The information you provided is unfortunately
insufficient for debugging the problem.

Could you please show a reproducible recipe, starting from "emacs -Q",
that includes loading ack-and-a-half and the minimal set of other
customizations needed to reliably reproduce the problem?

Also, please run Emacs under GDB, and when the problem happens,
produce a backtrace and post it here (as the bug report requests).
The backtrace will help us identify the place where Emacs segfaults,
and will maybe give other ideas.

It is very hard to debug the issue without all this information, and
no way to reproduce the crash, especially when the add-on package you
are using involves interaction with an external program.

Finally, I'd encourage you to try using the latest pretest of Emacs
24.4, in case this problem was already fixed in the development
sources.  You can find the pretest's tarball here:

  ftp://alpha.gnu.org/gnu/emacs/pretest/emacs-24.3.92.tar.xz

Thanks in advance.