Re: [PATCH] docs: Clarify what git-rebase's "--preserve-merges" does

From: Sergey Organov <sorganov@gmail.com>
Date: Mar 26, 2015, 21:17 UTC
Message-ID: <871tkblapv.fsf@javad.com>
In-Reply-To: <xmqqd23vzkon.fsf@gitster.dls.corp.google.com>

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

[...]

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> I think the current preserve-merges considers everything between
> <upstream> and <branch> as "commits to be rebased", and recreate
> merges across these rebased tips of branches that are merged.
>
> There however were repeated wishes (or wishful misunderstandings ;-)
> that there were a mode to rebuild the trunk, considering only the
> commits on the first-parent chain as "commits to be rebased",
> recreating the history by replaying the merge commits (whose first
> parent might be rewritten during the rebase, but the tips of side
> branches these merges bring into the history are kept intact).
>
> Surely there is no such mode right now,

Isn't it what Johannes Sixt <j6t@kdbg.org> mentions here?:

[QUOTE] If you want a version of --preserve-merges that does what *you* need, consider this commit:

  git://repo.or.cz/git/mingw/j6t.git rebase-p-first-parent

Use it like this:

  git rebase -i -p --first-parent ...

Beware, its implementation is incomplete: if the rebase is interrupted, then 'git rebase --continue' behaves as if --first-parent were not given. [/QUOTE].

ref: http://permalink.gmane.org/gmane.comp.version-control.git/263584

If so, then I'd say such mode almost exists.

> but I am fairly sure that I wouldn't have any objection against a
> patch to implement such a feature (perhaps "--first-parent
> --preserve-merges"?),

It'd be very welcome feature here, preferably along with a way to pass it to 'git pull --rebase', including a way to configure it to be the default.

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> and with or without such a feature in the system, I would be happier
> if we made sure that the description we are discussing to update makes
> it clear that the current behaviour is "everything between <upstream>
> and <branch>", and cannot be misread as "do not touch side branches
> instead of dropping merged commits".

I'd also suggest to somehow warn in the manual that current modes of operation silently drop changes to merge commits that were made to non-conflicting paths (either during conflict resolution or otherwise.)

-- Sergey.