bug#53924: 26.1; fontification sometimes fails for some characters despite available glyphs

[Eli Zaretskii <eliz@gnu.org>]

> Date: Tue, 15 Feb 2022 18:32:23 -0800
> From: "Greg A. Woods" <woods@robohack.ca>
> CC: GNU Emacs Bug Reports <53924@debbugs.gnu.org>
> 
> Hopefully this message encodes properly, it should be text/plain, in
> the ISO10646-1 charset, with BASE64 encoding.
> 
> Run "emacs -q" in the debugger, switch to the *scratch* buffer and
> insert the forms below, then:
> 
> M-x eval-buffer <return>
> 
> Switch to the new *Font Families* buffer and scroll slowly through it.
> Depending on how many fonts you have installed, and how, and what kind
> of resources your system(s) have, this could take quite a long time.
> 
> If that doesn't trigger a crash try going back to the beginning,
> increase the text scale with C-u C-x C-+ and scroll through again.
> 
> This seems to reliably cause the crash for me, at least with the Git
> master version I have built using the lucid toolkit..

Like I said before: please try to figure out which font causes the
crashes, and post a recipe with that font alone.  Otherwise, trying to
reproduce this is a huge waste of time, because the results depend
critically on the fonts actually installed on the system.

Thanks.