Subject: Re: bug#24064: 24.5; NULL pointer dereference in compute_motion(), indent.c

From: Eli Zaretskii <[email-masked]>
Date: Tue, 26 Jul 2016 18:35:07 +0300

> From: Clément Pit--Claudel <[email-masked]>
> Date: Mon, 25 Jul 2016 22:49:35 -0400
> Cc: [email-masked]
> 
> >>> I've prepared an elisp file to reproduce a crash:
> >>>
> >>> 1) Open it and move cursor to the end of the file
> >>> 2) Execute eval-buffer
> >>> 3) Press C-l several times
> >>
> >> Running this recipe does not cause a crash for me in GNU Emacs 25.1.50.7 (x86_64-pc-linux-gnu, GTK+ Version 3.18.9) of 2016-07-20.  Am I missing something?
> > 
> > It crashes for me on 24.5, but not on 25.0.95.  Perhaps it was fixed?
> 
> Indeed, same here. Crashes on 24.5, but not 25.

C-l (a.k.a. "recenter") no longer calls compute_motion in Emacs 25, so
to trigger the segfault, the recipe should be changed like this:

 1) Open it and move cursor to the end of the file
 2) Execute eval-buffer
 3) Type "M-x set-variable RET scroll-preserve-screen-position RET t RET"
 4) Type "C-u 1 C-v"

In addition, the above should be done on a TTY frame.

This 22-year old bug is now fixed on the master branch.

Thanks.