bug#28236: 'configure --with-cairo' causes 'emacs -font' to fail

[Eli Zaretskii]

> From: Ari Roponen <ari.roponen@gmail.com>
> Cc: Dmitry Gutov <dgutov@yandex.ru>,  28236@debbugs.gnu.org,  
> andrei.elkin@pp.inet.fi
> Date: Wed, 12 Dec 2018 14:03:48 +0200
> 
> >> On 25.08.2017 22:57, andrei.elkin@pp.inet.fi wrote:
> >> >    bash# src/emacs -Q -font 7x14
> >> >    => Font ‘7x14’ is not defined
> >> 
> >> FWIW, I can confirm with the latest emacs-26 and master.
> >
> > Thanks for trying.  AFAIU, this is an important user-level feature, so
> > we should try fixing it if we want to enable Cairo by default.
> >
> 
> I can get the same result also without Cairo:
>     emacs-26.1 --xrm "Emacs.fontBackend: xft" -q -font 7x14
> 
> When I copy the font where fontconfig can see it:
>     cp /usr/share/X11/fonts/misc/7x14.pcf.gz ~/.local/share/fonts/
>     fc-cache -vf
> I see this:
>     fc-list | grep 7x14
> =>  /home/arirop/.local/share/fonts/7x14.pcf.gz: Fixed:style=Regular
> 
> After that, using "-font Fixed" seems to work.

So you are saying that the problem here is that Cairo can only work
with fonts known fontconfig, and cannot switch to font backend(s) that
bypass fontconfig?  If so, perhaps just an entry in PROBLEMS with the
above recipe would suffice as a workaround?