Subject: Re: [PATCH 2/2] diff-merges: introduce '-d' option

From: Sergey Organov <[email-masked]>
Date: Tue, 26 Sep 2023 23:05:30 +0300

Junio C Hamano <[email-masked]> writes:

> Sergey Organov <[email-masked]> writes:
>
>> No need to ask for a new option, as the behavior you describe is already
>> there, and is spelled "git log --diff-merges=first-parent"
>> (--diff-merges=1 for short).
>
> Ah, that changes things.

Only a tiny bit, unfortunately, as I'm still struggling to finally
convince you (((

>
> Making "--diff-merges=<how>" only about the presentation of merge
> commits, requiring a separate "-p" for single-parent commits [*],
> does make the life for those in the "merges are the only interesting
> things" camp a lot easier, exactly because the lack of "-p" can be
> used to say "I am not interested in chanages by single-parent
> commits".
>
> 	Side note: I personally think it is a design mistake of
> 	--diff-merges=<how> (e.g., --cc and --diff-merges=cc do not
> 	behave the same way) but that is a different story, and it
> 	is way too late now anyway to "fix" or change.

        Side note: This has been considered and agreed upon when
        --diff-merges= options were introduced, and as far as I recall,
        at that time you explicitly agreed it might be useful to be able
        to get output only for merge commits.

        --cc is a simple alias for "--diff-merges=cc --patch" nowadays,
        so yes, they do behave differently, and that's by design. Dunno
        see any design mistake here, as we get all useful variations of
        behavior with a straightforward design, more frequent use-cases
        served by shorter options. Looks fine.

>
> So "-d" that stands for "--diff-merges=first-parent -p" makes the
> more useful (to those who think "merges are the only interesting
> things", which I do not belong to) "--diff-merges=first-parent"
> (without "-p") less useful.  And the combination is not useful for
> those of us who find individual patches plus tweaks by merges
> (either --cc or --remerge-diff) are the way to look at the history.

Yes, you have your --cc, -c, and --remerge-diff (that I'd call something
like --rd probably, but anyway). Could I please have my simple,
straightforward, mnemonic, and terribly useful "-d" as well?

In other words, will I finally be faced with "if you need it, do it
yourself" argument? ;)

> I still do not think that we want to give a short-and-sweet single
> letter option for such a combination.

I have very simple desire: convenient way to tell Git to show me diff to
the first parent for merge commits, as that's the thing I need 99% of
times when I do request diff output at all. That's exactly what I'd have
seen as changes when I was about to commit the merge as well, similar to
any other commit. It's so natural that I can't figure why it looks so
damn rare or unusual to you, and that it makes you argue so hard against
-d, especially when -p, -c, --cc, or even -m, are already there?

I do sympathize your desire to be careful about short options, but what
reservation for "-d" do you still have in mind? It seems that it was
just waiting for me to come and finally bring it to life with the best
meaning possible. How long should I wait for it to remain unused to
finally be able to make use of it?

Thanks,
-- Sergey Organov