bug#54993: 28.1; Editing etc/NEWS on master with Emacs 28 signals an error

[Eli Zaretskii <eliz@gnu.org>]

> From: Lars Ingebrigtsen <larsi@gnus.org>
> Cc: Michael Albinus <michael.albinus@gmx.de>,  54993@debbugs.gnu.org
> Date: Mon, 18 Apr 2022 13:12:31 +0200
> 
> Eli Zaretskii <eliz@gnu.org> writes:
> 
> > We could add NEWS to auto-mode-alist instead, and that would solve the
> > issue cleanly for everyone.  That was one of the original
> > alternatives, but somehow it was forgotten now.
> 
> My worry with that was that adding etc/NEWS to auto-mode-alist would be
> false positives (for other files with that name).  But I guess we could
> check that it's actually an Emacs NEWS file before enabling the mode.

I looked at several NEWS files in various projects, and they look well
under outline mode.  Which doesn't really surprise me, since NEWS is
AFAIR a GNU thing.

> But that would mean removing the mode: setting from NEWS itself, because
> mode: takes precedence over auto-mode-alist, I think?

Yes.

> So then we're back to people editing the file in Emacs 28 in
> fundamental-mode.

Yes.  So maybe instead Outline mode in Emacs 29 could turn on
emacs-news-mode automatically when the file's name is NEWS or NEWS.*
or ONEWS.

> > Btw, another issue with emacs-news-mode is that it invokes
> > outline-minor-mode, which means all the headings-related commands are
> > now bound to different keys than they were before.  Wouldn't it be
> > better if emacs-news-mode were a minor mode invoked by Outline
> > instead?
> 
> emacs-news-mode is quite major-modeish, though, so I think that would be
> awkward.

I don't see why.  What do you see in emacs-news-mode that doesn't fit
a minor mode?

I guess my point is that making it a major mode makes this a
backward-incompatible change, when we consider editing of NEWS.  If we
can avoid that, it would be better.

Or maybe it's enough to make it be derived from Outline (if that
doesn't interfere with editing NEWS with older Emacsen)?