bug#54188: Crash when eval-ing font test elisp code

[Eli Zaretskii]

> Date: Sun, 27 Feb 2022 22:33:45 +0200
> From:  Vordoo via "Bug reports for GNU Emacs,
>  the Swiss army knife of text editors" <bug-gnu-emacs@gnu.org>
> 
> Hi,
> 
> 1. Start emacs  -Q [28.0.91  or  28.0.60]
> 
> 2. eval-buffer containing:
>
> (require 'cl-lib)
> 
> (require 'cl-extra)
> 
> (let ((str "The quick brown fox jumps over the lazy dog 
> ´`''\"\"1lI|¦!Ø0Oo{[()]}.,:; ")
> 
>        (font-families (cl-remove-duplicates
> 
>                (sort (font-family-list)
> 
>                  (lambda(x y) (string< (upcase x) (upcase y))))
> 
>                :test 'cl-equalp)))
> 
>    (dolist (ff font-families)
> 
>      (insert
> 
>       (propertize str 'font-lock-face `(:family ,ff))               ff "\n"
> 
>       (propertize str 'font-lock-face `(:family ,ff :slant italic)) ff 
> "\n")))
> 
> 
> 3. Emacs crash
> 
> Thread 1 "emacs" received signal SIGSEGV, Segmentation fault.
> 0x0000555555790ec1 in fontset_find_font ()

I cannot reproduce this here.

In general, trying to use Emacs with arbitrary fonts is not a good
idea, as not every font can be used by Emacs.