bug#52905: 29.0.50; "fixed-pitch" face doesn't respect the font in "default-frame-alist"

[Eli Zaretskii]

> From: Dima Kogan <dima@secretsauce.net>
> Cc: 52905@debbugs.gnu.org
> Date: Fri, 31 Dec 2021 00:24:53 -0800
> 
> Eli Zaretskii <eliz@gnu.org> writes:
> 
> > Thanks, but I don't think we should fix this.  I see no problem to
> > fix.  The fixed-pitch face is designed to have a distinct font.
> 
> OK. Can we then at least update the docs? This page:
> 
>   https://www.gnu.org/software/emacs/manual/html_node/emacs/Fonts.html
> 
> That page tells the user how to change the font, but don't say anything
> about when that setting will be respected.

You mean, to say explicitly that "the default font" in that node means
"the font of the default face"?

> The current behavior of emacs
> completely ignoring this setting when picking the "fixed-pitch" and
> "variable-pitch" fonts feels like it should be noted on that page.

That behavior is not specific to these faces, it happens with any face
which specifies a font.

> Is using the default-frame-alist to set the default font still our
> recommended best practice? Is that what you do?

Yes and yes.  It's just that you seem to interpret "the default font"
differently from what it was supposed to mean.  It means the font of
the default face.  Any face that doesn't specify a font or some font
attribute will use the same font, but faces that do specify those
attributes can (and usually do) select other fonts.  To affect the
font of the faces which specify font attributes, you need to customize
those faces separately from the default face and default-frame-alist.