bug#59347: 29.0.50; `:family` face setting ignored

[Eli Zaretskii <eliz@gnu.org>]

> Date: Mon, 21 Nov 2022 23:34:18 +0000
> From: Gregory Heytings <gregory@heytings.org>
> cc: monnier@iro.umontreal.ca, 59347@debbugs.gnu.org
> 
> With current master, the variable-pitch face is realized as follows:
> 
> - with 1-3: -ADBO-Source Code Pro-black-normal-normal-*-29-*-*-*-m-0-iso10646-1, which is a monospace font
> 
> - with 4: -PfEd-DejaVu Sans-bold-normal-normal-*-29-*-*-*-*-0-iso10646-1, which is a variable pitch font
> 
> - with 5: -ADBO-Source Code Pro-semibold-normal-normal-*-29-*-*-*-m-0-iso10646-1, which is again a monospace font
> 
> - with 6: -urw-nimbus sans l-regular-r-normal--29-210-100-100-p-158-iso8859-1, which is a variable pitch font but without anti-aliasing
> 
> - with 7: -PfEd-DejaVu Sans-regular-normal-normal-*-29-*-*-*-*-0-iso10646-1, which is a variable pitch font
> 
> - with 8-9: -ADBO-Source Code Pro-light-normal-normal-*-29-*-*-*-m-0-iso10646-1, which is again a monospace font
> 
> - with 10-11: -PfEd-DejaVu Sans-ultralight-normal-normal-*-29-*-*-*-*-0-iso10646-1, which is a variable pitch font
> 
> That can't be right.  Only 4, 7, and 10-11 correspond to what is expected 
> for that face, namely a variable pitch font.

Why do you expect to get a variable pitch font?  We don't have any way of
expressing that in font attributes, do we?  Emacs tries to find a font from
the same family, but if that fails for some reason, all bets are off wrt
whether the font we find will be variable-pitch or not.  Or what am I
missing?