bug#66589: 30.0.50; core dump in redisplay

[Eli Zaretskii <eliz@gnu.org>]

> From: Evgeny Zajcev <lg.zevlg@gmail.com>
> Date: Tue, 17 Oct 2023 16:36:17 +0300
> Cc: 66589@debbugs.gnu.org
> 
> And which Emacs 29 are we talking about -- Emacs 29.1 as released or
> > the current emacs-29 branch?
> >
> >
> I've been using GNU Emacs 29.0.50 (build 1, x86_64-pc-linux-gnu, GTK+
> Version 3.24.20, cairo version 1.16.0) before moving to Emacs30

Emacs 29.0.50 is before Emacs 29.1 was released?

> (gdb) up 18
> #18 produce_glyphless_glyph (it=0x7ffef46c5660,
> for_no_font=for_no_font@entry=false, acronym=acronym@entry=0x0) at
> xdisp.c:32165
> 32165             sprintf (buf, "%0*X", it->c < 0x10000 ? 4 : 6, it->c +
> 0u);
> (gdb) p it->c
> $1 = -233054
> (gdb)

This is not a valid character, I wonder how it got to this function.
Please do the below and tell what GDB produces as result:

  (gdb) frame 18
  (gdb) p/x it->c
  (gdb) p/x it->char_to_display
  (gdb) p it->method
  (gdb) pgrowx it->glyph_row

If GDB says it doesn't know abot "pgrowx", type this:

  (gdb) source /path/to/emacs/src/.gdbinit

and then repeat the pgrowx command.

Also, any chance you can describe what were you doing when the abort
happened?  In particular, what was in the buffer that was on display
in this window?