Re: Adding git-commit highlight mode?

[Stefan Kangas <stefankangas@gmail.com>]

Eli Zaretskii <eliz@gnu.org> writes:

>> From: Stefan Kangas <stefankangas@gmail.com>
>> Date: Thu, 2 Jan 2025 14:10:22 -0600
>> Cc: emacs-devel@gnu.org, Jonas Bernoulli <jonas@bernoul.li>
>>
>> > I thought of deriving from text-mode. I don't know much of change-log-
>> > mode besides what it says in the mode title and now that I'm looking at
>> > mode description it also sounds pretty vague. So… I could derive it
>> > from change-log-mode if you think it's useful, but I'd rely on your
>> > judgment here 😊
>>
>> `change-log-mode` implements the anachronistic ChangeLog format favored
>> by GNU.
>
> That "anachronistic format" allows plain text, so I don't quite see
> how using change-log-mode as the parent mode will cause us lose
> anything?  What's the harm in getting everything text-mode descendants
> can do, plus support for "anachronistic" formats?

I'm concerned that it would get in the way of editing commit messages
that do not use the ChangeLog format.  It seems to me that
`change-log-mode' would need quite a bit of adapting not to do that.
For example, `open-line` in that mode adds a tab character at the
beginning of the line.  It would also contribute to some confusion, when
users try to figure out what ChangeLog's are, and why they are needed to
use Git.

Instead of inheriting from it, I'd propose creating an optional minor
mode, that users can enabled when they need to, plus a globalized mode
for those that want it on always.  That would also expand it to be
useful also with Magit's `git-commit-mode`, for example, which I'd
personally welcome.  (FWIW, I happen to think that the paragraph filling
rules would be the most interesting feature in such a minor mode.)