bug#9645: 24.0.50; Assertion failure in Emacs 24 pretest

[Eli Zaretskii <eliz@gnu.org>]

> From: John Wiegley <jwiegley@gmail.com>
> Date: Fri, 30 Sep 2011 22:56:03 -0500
> 
> I ran this command sequence in the Emacs 24 pretest, updated yesterday:
> 
>   M-x shell-command RET make-emacs& RET
> 
> And crashed with this backtrace:
> 
>     #0  0x00007fff8a4b50b6 in __kill ()
>     #1  0x00007fff8a5559f6 in abort ()
>     #2  0x0000000100036c01 in move_it_by_lines (it=0x7fff5fbf9680, dvpos=0) at /Users/johnw/.emacs.d/devel/src/xdisp.c:8688
>     #3  0x000000010008614e in Frecenter (arg=-4) at /Users/johnw/.emacs.d/devel/src/window.c:5130

I cannot reproduce this with either today's trunk or the pretest.
Maybe there's something special in your make-emacs script, whose
contents you left unpublished.  (I just put there a single "make"
command with a few switches, which is what I normally use to build
Emacs.)  Or maybe this doesn't happen in "emacs -Q", and some optional
features need to be turned on for it to happen.

Also, the line numbers you show in the backtrace differ considerably
from what I see in the pretest sources: e.g., move_it_by_lines there
starts at line 8834, and the only place it can call `abort' is on line
8858:

      xassert (it->current_x == 0 && it->hpos == 0);

So I'm unable to proceed without either a way to reproduce this crash
or some additional information from you.

Also, please start the debugger from the `src' directory, so that it
also shows the Lisp backtrace that corresponds to the C backtrace.