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 16:04:57 +0100
> 
> Eli Zaretskii <eliz@gnu.org> writes:
> 
> >       if (pcm)
> >         {
> >           it->phys_ascent = pcm->ascent + boff;
> >           it->phys_descent = pcm->descent - boff;
> >           it->pixel_width = pcm->width;
> >
> > please tell what are the values of pcm->ascent and pcm->descent.
> >
> > I want to know whether the font is the culprit or some code of ours
> > overrides the value from the font.  Then we can devise the solution.
> 
> gdb) next
> 30909               it->phys_ascent = pcm->ascent + boff;
> (gdb) p pcm->ascent 
> $1 = 18
> (gdb) p pcm->descent 
> $2 = -3

So the glyph metrics also report a negative descent.

But what about the font?  We don't use the above for it->descent, at
least not directly.  So where in the code did it->descent get
negative?