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

[Gregory Heytings <gregory@heytings.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?
>

The variable-pitch face should use a variable pitch font, shouldn't it? 
Unless there are no such fonts installed on the computer of course, in 
which case it could fall back to a monospace font.

>
> 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?
>

Why should the weight of the default face influence the font selected for 
the variable-pitch face, to the point that even when variable pitch fonts 
are installed on the computer, they are all flatly rejected because they 
do not explicitly support say the 'semi-bold' weight?  The weight of the 
default face should only influence the weight of the other faces, which is 
what it does with the patch.  With a 'semi-bold' default face, a 'bold' 
variable pitch font is a legitimate candidate for the variable-pitch face.