bug#6621: Emacs crash when trying to report emacs crash

[Eli Zaretskii <eliz@gnu.org>]

> Date: Tue, 13 Jul 2010 21:29:20 +0300
> From: Yair F <yair.f.lists@gmail.com>
> Cc: Kenichi Handa <handa@m17n.org>, 6621@debbugs.gnu.org
> 
> On Tue, Jul 13, 2010 at 8:57 PM, Eli Zaretskii <eliz@gnu.org> wrote:
> >> Date: Tue, 13 Jul 2010 19:15:33 +0300
> >> From: Yair F <yair.f.lists@gmail.com>
> >> Cc: 6621@debbugs.gnu.org
> >>
> >> (gdb) frame 7
> >> #7  0x0809c519 in get_next_display_element (it=0xbfffc338) at xdisp.c:6051
> >> 6051              it->face_id = FACE_FOR_CHAR (it->f, face, it->c,
> >> pos, it->string);
> >> (gdb) pit
> >> cur=150[276] pos=150[276] start=128[235] end=3160 stop=3160 face=13 MB
> >> ch=[4195671,2]
> >> vpos=6 hpos=15 y=102 lvy=561 x=98 vx=0-640 w=0 a+d=13+4=17 max=13+4=17
> >
> > Strange.  Looks like the iterator indeed loaded this value 4195671
> > somehow.  But it claims that the character took 2 bytes, which is
> > correct for HET, but incorrect for such large values.  Perhaps
> > Handa-san will have ideas.
> >
> 
> I found a shorter way to reproduce the problem :
> 1. start with emacs -Q
> 2. create a buffer
> 3. paste the first 7 lines from the file *without the newline*
> 4. while at EOB press enter
> Emacs is now at a strange state: the cursor does not go to a new line
> as expected,
>  but C-x= reports column=0. going back to point 149 make the cursor invisible
> 
> Pressing return again crashes emacs with the flowing trace:
> Breakpoint 1, abort () at emacs.c:430
> 430       kill (getpid (), SIGABRT);
> (gdb) bt
> #1  0x0809cd6b in set_iterator_to_next (it=0xbfffdee4, reseat_p=1) at
> xdisp.c:6254

My Emacs is not compiled with -DENABLE_CHECKING, so the assert
triggered here is a no-op for me, and Emacs works for me just fine
with this recipe.

I will build with -DENABLE_CHECKING and try again, but until I
do, could you please show the output of the`pit' command in frame #1?

Also, in the same frame #1, what do these commands show:

  (gdb) pgrowx it->glyph_row
  (gdb) prowlims it->glyph_row
  (gdb) pmtxrows it->w->desired_matrix

Finally, does the problem persist if you turn off
auto-composition-mode before pasting the text?