bug#37774: 27.0.50; new :extend attribute broke visuals of all themes and other packages

[Ergus]

Hi Eli and Martin:

I have seen these reports and also the ones in reddit. Do you think that
we should/must/can do anything about?



On Wed, Oct 16, 2019 at 10:53:21AM +0300, Eli Zaretskii wrote:
> > From: Andrey Orst <andreyorst@gmail.com>
> > Date: Wed, 16 Oct 2019 10:00:38 +0300
> >
> > Somewhat last checkout from master brought the change of face
> > attributes, adding new `:extend` attribute, which make all themes, and
> > packages like Magit display weirdly.  By this I mean that before the
> > change, some faces were set up to extend highlighting beyond EOL, but
> > now all of those faces are not doing this.  I've first reported this to
> > the theme package I'm using:
> > https://github.com/hlissner/emacs-doom-themes/issues/342 but I think
> > that this should be handled by emacs itself, because if not it will
> > result in the duplicated or extra code in themes fro different Emacs
> > versions.  This reddit post has some screenshots of what I mean:
> > https://www.reddit.com/r/emacs/comments/diahh1/emacs_27_update_changed_how_highlighted_lines/
>
> The screenshots you posted don't clearly explain the problem.  Some of
> them seem actually identical before and after the change, and with
> others I don't think I see the problem.
>
> So please explain what exactly is incorrect or "weird" in the visual
> appearance after the change.  Specifically, why the faces in question
> need to be extended past EOL?
>
> Thanks.