bug#57555: 29.0.50; variable-pitch font issue with medium weight default font

[Amin Bandali <bandali@gnu.org>]

Eli Zaretskii writes:

>> From: Amin Bandali <bandali@gnu.org>
>> Cc: 57555@debbugs.gnu.org
>> Date: Mon, 05 Sep 2022 03:06:48 -0400
>> 
>> Eli Zaretskii writes:
>> 
>> [...]
>> >
>> > Thanks, but please show the font setup you are using; without that, the
>> > "instead of the correct sans-serif variable-pitch font" part is
>> > impossible to interpret.
>> 
>> Thanks for your reply, Eli.  Globally, I'm basically using the default
>> font setup that Trisquel GNU/Linux comes with.  Here is a tarball of
>> the /etc/fonts/ directory on my system:
>
> Thanks, but I meant the font setup specific to Emacs, i.e.:
>
>   . any set-fontest-font calls in your init files
>   . any set-frame-font calls or any other face-related calls in your
>     init files that could affect the font selection
>
> Sorry for my imprecise wording.

Ah, right.  No problem. :-)  Other than setting the Emacs font from
Xresources (though I also did try with set-frame-font per my initial
email, with the same results), this is pretty much all I have in my
init file that's related to fonts:

(when (display-graphic-p)
  (set-fontset-font t 'arabic "Vazir"))

And further down:

(when (display-graphic-p)
  (with-eval-after-load 'faces
    (let ((grey "#e7e7e7"))
      (set-face-attribute 'fixed-pitch nil :family "Source Code Pro")
      (set-face-attribute 'mode-line nil
                          :background grey
                          :inherit 'fixed-pitch))))

[...]
>
> I think this means that Emacs gives greater importance to consistency
> in weight than to consistency of the family.  Not sure if that is TRT.

Hmm, right.  That may indeed not be TRT: at least in this case (and
with various other fonts I've tried/used in the past), their weights
don't necessarily match.  For instance, I find Source Code Pro's
regular weight way too thin, and I prefer to use its medium weight
wherever possible.  It's more readable and much more closely matches
the regular weight of GNU FreeSans and most other sans fonts on my
machine.

>> Right.  For what it's worth, I find Emacs picking misc-fixed for
>> variable-pitch text more than just a minor annoyance: for long hours
>> of use, I find misc-fixed it considerably less comfortable to my eyes
>> than GNU FreeSans (for proportional/variable-pitch) or Source Code Pro
>> medium (for monospace).
>
> Can't you customize the variable-pitch face to specify the FreeSans
> family, or even to specify the exact font you want Emacs to use?  That
> should allow you to override any built-in heuristics that Emacs uses
> when it has no other restrictions.
>

This indeed doesn't seem to work anymore.  With the following,

    (set-face-attribute 'variable-pitch nil :family "FreeSans")

Emacs picks/uses Source Code Pro medium for variable-pitch (confirmed
visually and with describe-char), even though describe-face for
variable-pitch shows the family set as "FreeSans".  This used to work
before, but not anymore.