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

From: Sergey Organov <sorganov@gmail.com>
Date: Sep 7, 2021, 19:53 UTC
Message-ID: <878s089n79.fsf@osv.gnss.ru>
In-Reply-To: <xmqqy288b64q.fsf@gitster.g>

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

Show 6 quoted lines

> Sergey Organov <sorganov@gmail.com> writes:
>
>> Here is a patch that fixes diff-index to accept --cc again:
>
> Sorry for the delay; I did not notice there was a patch buried in a
> discussion thread.

Sorry from my side as well. I was already about to re-submit the patch properly, but you happened to be faster with this )

Show 13 quoted lines

>
> We might later need to do this suppression in more codepaths if we
> find more regressions, but let's have one fix at a time.  
>
> Will queue.
>
>>  builtin/diff-index.c |  6 +++---
>>  diff-merges.c        | 14 ++++----------
>>  diff-merges.h        |  2 +-
>
> This would deserve new tests that cover the existing use cases,
> given that both of us (and other reviewers in the original thread)
> did not notice how big a regression we are causing.

Yep, it's too easy to break undocumented and untested behavior.

> We care about --cc naturally falling back to -p when there is only
> one other thing to compare with, and also we care about --cc that
> allows us to compare during conflict resolution, at least, I think.

I'm all for more tests, but I'm afraid I'm not in a good position to write them, especially for an undocumented behavior. I think somebody should first document what --cc/-c does in diff-index, and only then it makes sense to write some tests.

> It can and should come as a separate step, of course.  Unbreaking
> gitk for an already known breakage would be more urgent than hunting
> for other breakages, even though the latter might result in a more
> thorough fix in the end.

Makes sense.

Thanks, -- Sergey Organov