bug#50179: [PATCH] Add support for "bright" ANSI colors to ansi-color and term-mode

[Jim Porter <jporterbugs@gmail.com>]

On Tue, Aug 24, 2021 at 10:59 AM Eli Zaretskii <eliz@gnu.org> wrote:
>
> > From: Jim Porter <jporterbugs@gmail.com>
> > Date: Tue, 24 Aug 2021 10:38:06 -0700
> > Cc: 50179@debbugs.gnu.org
> >
> > > I wouldn't offer a customizable list for this: users have no
> > > particular reason to redefine standard colors.
> >
> > I made this a defcustom because `ansi-color-faces-vector' and
> > `ansi-color-names-vector' are defcustoms too. More practically
> > speaking, I'd want to customize this new variable to make these colors
> > match the Emacs theme I use. I chose colors in this patch to
> > complement `ansi-color-names-vector', but they'd clash with my theme.
>
> How can named colors change with the theme?  Faces can, but colors are
> absolute.  Bright-yellow is the same color whatever the theme.  At
> least IMO.  I wonder if others think otherwise.

The colors in `ansi-bright-color-names-vector' are just the color
values that get used to set face attributes on bits of text. They (and
the values in the other defcustoms mentioned above) get compiled into
`ansi-color-map', which contains entries like `(foreground-color .
"yellow2")'. Those then get applied as face attributes onto the
relevant text. While you'd always want bright-yellow to be some kind
of bright-looking yellow, the exact RGB value for that is just a
matter of preference. In particular, a theme might need to adjust
these color values so that there's appropriate contrast between
ANSI-colorized text and the default foreground/background color
specified by the theme.

> > Would it be ok to use `ansi-color-bold-is-bright'
> > (from patch 1 in `ansi-color.el') in `term.el'?
>
> Yes, why not?

Mostly just my relative unfamiliarity with the preferred way to do
things here. `ansi-color.el' and `term.el' seemed very independent of
each other, and I wasn't sure if there was a particular reason for
that. I'll just use `ansi-color-bold-is-bright' for both patches then.