Re: [PATCH RFC] rebase: respect --ff-only option

From: Felipe Contreras <felipe.contreras@gmail.com>
Date: Jul 5, 2021, 12:09 UTC
Message-ID: <60e2f68057ebe_1b8e782087d@natae.notmuch>
In-Reply-To: <xmqq8s2lnkta.fsf@gitster.g>

Junio C Hamano wrote:

Show 21 quoted lines

> Phillip Wood <phillip.wood123@gmail.com> writes:
> 
> > As I understand it the motivation for this change is to have 'git -c
> > pull.rebase=true pull --ff-only' actually fast forward. Why cant we
> > just change pull not to rebase in that case?
> > ...
> > Is there a use for this outside of 'git pull --ff-only'? I'm far from
> > convinced we want this new option but if we do end up adding it I
> > think it should error out in combination with '-i' or '-x' as '-i'
> > implies the user wants to change the existing commits and '-x' can end
> > up changing them as well.
> >
> > I think this patch addresses a valid problem but it seems to me that
> > the approach taken pushes complexity into rebase to handle a case when
> > pull does not need to invoke rebase in the first place.
> 
> I share the sentiment, but my conclusion would be different.
> 
> Even though we explain that "pull" is _like_ "fetch" followed by
> "merge" (or "rebase"), at the conceptual level, "pull --ff-only"
> should not have to invoke merge or rebase backend.

Indeed. I'm about to send a patch series that adds the `git fast-forward` command, so `git pull` doesn't even have to call either of those.

This cleanly separates the logic, except --ff-only remains purely for `git merge`, and instead there's a new:

  git -c pull.mode=fast-forward pull

Now it's 100% clear what these three do:

  git -c pull.mode=fast-forward pull
  git -c pull.mode=merge pull
  git -c pull.mode=rebase pull

-- 
Felipe Contreras