Re: Crash with --enable-checking and some glyphs

[Eli Zaretskii]

> From: Lars Ingebrigtsen <larsi@gnus.org>
> Cc: rpluim@gmail.com,  emacs-devel@gnu.org
> Date: Fri, 26 Nov 2021 13:18:58 +0100
> 
> Eli Zaretskii <eliz@gnu.org> writes:
> 
> > Please show a full backtrace, maybe it can provide some hints or
> > ideas.  Also, the values of the variables involved in this.
> 
> I haven't really tried to debug this at all -- I just wondered whether
> I'm the only person in the universe that's seeing the issue, and it
> seems like I am?
> 
> Here's the results from gdb with -O2:
> 
> #0  raise (sig=sig@entry=6) at ../sysdeps/unix/sysv/linux/raise.c:49
> #1  0x00005555555a6e5e in terminate_due_to_signal
>     (sig=sig@entry=6, backtrace_limit=backtrace_limit@entry=2147483647)
>     at emacs.c:443
> #2  0x00005555555acd6e in die
>     (msg=msg@entry=0x555555825948 "it->ascent >= 0 && it->descent >= 0", 
> file=file@entry=0x5555558230a8 "xdisp.c", line=line@entry=31556) at 
> alloc.c:7491
> #3  0x000055555559d065 in gui_produce_glyphs (it=<optimized out>)
>     at xdisp.c:31556

What does the following show?

 (gdb) fr 3
 (gdb) source /path/to/emacs/src/.gdbinit
 (gdb) p it->what
 (gdb) p/x it->c
 (gdb) pgrowx it->glyph_row

The last command should display the entire glyph row you have there,
which maybe will tell us something useful.  The two commands before it
could also be useful.