Re: diff-index --cc no longer permitted, gitk is now broken (slightly)

From: Sergey Organov <sorganov@gmail.com>
Date: Sep 17, 2021, 18:41 UTC
Message-ID: <878rzv59k9.fsf@osv.gnss.ru>
In-Reply-To: <xmqqbl4ri2mq.fsf@gitster.g>

Junio C Hamano <gitster@pobox.com> writes:

Show 9 quoted lines

> Sergey Organov <sorganov@gmail.com> writes:
>
>> Ah, now I see, but it's exactly lack of documentation (and tests) that I
>> was referring to as the "problem of the historical status quo" on the
>> Git side, so I was somewhat confused by your original response.
>
> Well, you said the fixup "restores" the status quo, but in fact,
> with or without the fixup, before or after it, the lack of
> documentation was there.

No, what problematic patch did, it changed behavior of diff-index exactly in accordance with its *current* documentation that doesn't mention --cc as accepted command-line option for diff-index. So, with that patch applied, there were no this problem with documentation anymore. Implementation now actually matched the docs.

Unfortunately, that brought worse problem: it unexpectedly broke gitk, that, as it appeared, depends on undocumented diff-index behavior.

So, I re-enabled --cc in diff-index, lesser of two evils, that brought back the problem of lack of documentation and test cases for "diff-index --cc". This way, the status quo has been restored indeed.

Show 10 quoted lines

> So I thought you were talking about something else.
>
>>> I wanted to give you some credit for having worked on "--diff-merges",
>>> an effort to generalize things in a related area.
>>
>> Thanks for that! More to follow )
>
> I somehow expect there was need for no further work in this area,
> but there are also many other areas in Git where your talent is
> applicable and appreciated, I am sure ;-)

I'm afraid we still didn't reach one of the ultimate goals of all this: letting -m be useful again, specifically, as suitable *user* option.

Also, current --diff-merges options are incapable of providing current -m behavior, as has been noticed by Jonathan Nieder in another thread on reverting "-m implies -p" commit:

  "When I try it locally, -m shows no diff by default,
   whereas --diff-merges=separate shows a diff for merges."

and I'm going to fix this by adding yet another feature for --diff-merges. This is to be pure addition, thus causing no backward compatibility problems.

Thanks, -- Sergey Organov