bug#46358: 28.0.50; [PATCH] Add vc-dir faces; also apply them to vc-git

[Eli Zaretskii <eliz@gnu.org>]

> From: Protesilaos Stavrou <info@protesilaos.com>
> Date: Sun, 07 Feb 2021 13:42:09 +0200
> 
> In the attached patch, I do the following:
> 
> 1. Define new faces.  Each has semantic value in that it applies to
>    constructs implied by its name.

Thanks.  Would it be possible to use color names rather than #RRGGBB
values?  The latter makes it very hard to figure out the color that
will be used by the face.

> 4. Use new color combinations which conform with the WCAG AAA standard
>    for color contrast against pure white/black (this standard pertains
>    to legibility and is the highest of its kind).

Not sure what that means in practical terms: most Emacs users I've
watched working (myself included) use some background color other than
pure black or white.  Doesn't that change the contrast and the optimal
colors?

> With regard to point 2, I only use Git and thus cannot test the other
> backends with the requisite degree of confidence.  Do you think I should
> try regardless?  Or should we just support the Git backend and hope that
> someone else will work on [some of] the other backends?

If you can easily try other backends, it will be appreciated.  But it
is not mandatory, IMO.

> On point 4, please consider this a proposal: it is a highly opinionated
> change.  If you feel we should in no way alienate existing users, I am
> prepared to remove all colors and just :inherit from the faces that
> applied before.

Personally, I think inheriting from the existing faces will be less
drastic, so it's probably better.