Re: On-branch topic description support?

From: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
Date: Jul 21, 2022, 17:51 UTC
Message-ID: <220721.865yjqtksg.gmgdl@evledraar.gmail.com>
In-Reply-To: <xmqqk086id1k.fsf@gitster.g>

On Thu, Jul 21 2022, Junio C Hamano wrote:

Show 31 quoted lines

> Konstantin Ryabitsev <konstantin@linuxfoundation.org> writes:
>
>> On Thu, Jul 21, 2022 at 04:53:18PM +0200, Ævar Arnfjörð Bjarmason wrote:
>>> I tried now with "git rebase --rebase-merges -i", and it supports it
>>> properly, i.e. I could re-arrange it so that it's:
>>> 
>>>               A---C---B---M topic
>>>              / \         /
>>>         X---Y   ---------
>>>              \
>>>               master
>>
>> This is clever, but it has a hard restriction that nothing happens to A:
>>
>> - you can't move it so it's B---A---C---M
>> - you can't squash A+B
>>
>> Unless all the tools are taught to properly modify the merge commit.
>>
>> Or am I not reading this right?
>
> I think the drawing is about a two-commit topic that has B and C
>
> Or the drawing is wrong and M's other parent should have been Y.
> IOW, "git merge-base M^1 M^2" is the bottom of the topic (and our
> ranges always exclude the bottom end, X..Y does not include X but
> does include Y).  "git rev-list M^1...M^2" are the commits on the
> topic.
>
> Then you can shuffle A--B--C in whatever way you like with "rebase
> -i" or "filter-branch", using "git merge-base M^1 M^2" as the base.

Yes, those last two should be:

              A---B---C---M topic
             /           /
        X---Y------------
             \
              master

And:

              A---C---B---M topic
             /          /
        X---Y-----------
             \
              master

I.e. you could re-arrange it so that it's:

              C---B---A---M topic
             /          /
        X---Y-----------
             \
              master

Or whatever, sorry about that mix-up.