bug#66589: 30.0.50; core dump in redisplay

[Florian Weimer]

* Eli Zaretskii:

> Very strange.  This means that both it->char_to_display and it->c are
> bogus, and I have no idea how this could happen.  So it is very
> important that you try to provide a reproduction recipe for this.  I
> will nevertheless try to see if I can figure out how such a situation
> could ever happen.

For me, this (negative it->c value and subsequent fortify crash in
sprintf) happens when displaying an Arabic spam message.  This only
happens during article display.  Copying the message header and text
into a different buffer under text-mode Emacs and then opening it in
graphical Emacs does not trigger the crash for me.

Thanks,
Florian