Re: [PATCH 6/6] diff-merges: let -m imply -p

From: Elijah Newren <newren@gmail.com>
To: Sergey Organov <sorganov@gmail.com>
Cc: "Junio C Hamano" <gitster@pobox.com>, "Jeff King" <peff@peff.net>,
	"Philip Oakley" <philipoakley@iee.email>,
	"Felipe Contreras" <felipe.contreras@gmail.com>,
	"Ævar Arnfjörð Bjarmason" <avarab@gmail.com>,
	"Alex Henrie" <alexhenrie24@gmail.com>,
	"Git Mailing List" <git@vger.kernel.org>
Subject: Re: [PATCH 6/6] diff-merges: let -m imply -p
Date: Tue, 11 May 2021 11:31:03 -0700	[thread overview]
Message-ID: <CABPp-BEwp5bWWaBkv-G+OAJgd+pcsB=GoMCBd+gnhK5JAAnFgQ@mail.gmail.com> (raw)
In-Reply-To: <87v97pv04p.fsf@osv.gnss.ru>

On Tue, May 11, 2021 at 7:03 AM Sergey Organov <sorganov@gmail.com> wrote:
>
> Junio C Hamano <gitster@pobox.com> writes:
>
> > Junio C Hamano <gitster@pobox.com> writes:
>
> [...]
>
> > If we enable "some kind of diff" for "-m", I actually think that by
> > default "git log -m" should be turned into "log --cc".  As you told
> > Alex in your response, "log -m -p" is a quite unpleasant format to
> > read---it is there only because it was the only thing we had before
> > we invented "-c/--cc".
>
> Please, no! --cc has unfortunate feature of outputting exactly nothing
> for a lot of merge commits, causing even more confusion than historical
> "-m -p" format.
>
> The best default for -m output is --diff-merges=first-parent. Everybody
> is familiar with it, and it's useful.
>
> > But that might be outside the scope of this series.  I dunno, but if
> > there is no other constraints (like backward compatibility issues),
> > I have a moderately strong preference to use "--cc" over "-m -p"
> > from the get go for unconfigured people, rather than forcing
> > everybody to configure
>
> I rather have strong preference for --diff-merges=first-parent. --cc is
> only suitable for Git experts, and they know how to get what they want
> anyway. Yep, by using --cc. Why spare yet another short option for that?

Interesting.  I have a strong preference for --diff-merges=remerge
(yeah, I know it's not upstream, but it's been ready to submit for
months, but just backed up behind the other ort changes.  Sorry, I
can't push those through any faster).  I've had others using it for
about 9 months now.

I think --cc is a lot better than -m for helping you find what users
changed when they did the merge, but I agree the format is somewhat
difficult for many users to understand.  (--diff-merges=remerge, or
--remerge-diff, fixes these problems, IMO.)  I think
--diff-merges=first-parent, while fine when explicitly requested on
the command line, would be wildly misleading as a default because it
would attribute changes to a merge commit that were made elsewhere.

> Overall, let's rather make -m give diff to the first parent by default.
> Simple. Useful. Not confusing.

I think it's confusing.