Subject: Re: On-branch topic description support?

From: Junio C Hamano <[email-masked]>
Date: Thu, 21 Jul 2022 10:16:32 -0700

Ævar Arnfjörð Bjarmason <[email-masked]> writes:

> To steal and amend a diagram from git-merge(1), we now have turned this:
>
>
>               A---B---C topic
>              / 
>         X---Y
>              \
>               master
>
> Into this:
>
>               A---B---C---M topic
>              / \         /
>         X---Y   ---------
>              \
>               master

If you mean your topic have 3 commits, then I think you want the
first parent of M to be Y, not A, but I agree the above arrangement
can also represent what I was discussing.

The thing is, it is unclear if such an artificial merge is an easy
thing to maintain by individual contributors.  "rebase -i" with some
extra options people are not familiar with may be able to reproduce
the topology without losing information after you accumulate more
commits on top of M (e.g. you build D and E on top of M and now you
want to make it A-B-C-D-E merged into Y with M that records the tree
of E; you'd amend M's message to talk also about D and E), but
"it is possible" is different from "people are comfortable doing".

If M did not have a backpointer to the other parent, and instead
were an empty commit, then you recreated what I wrote in the message
you are responding to.