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From: "Matwey V. Kornilov" <>
To: Johannes Schindelin <>
Subject: Re: rebase preserve-merges: incorrect merge commits
Date: Mon, 8 Jan 2018 17:46:09 +0300	[thread overview]
Message-ID: <> (raw)
In-Reply-To: <>

2018-01-08 17:42 GMT+03:00 Matwey V. Kornilov <>:
> 2018-01-08 16:56 GMT+03:00 Johannes Schindelin <>:
>> Hi Matwey,
>> On Mon, 8 Jan 2018, Matwey V. Kornilov wrote:
>>> I think that rebase preserve-merges algorithm needs further
>>> improvements. Probably, you already know it.
>> Yes. preserve-merges is a fundamentally flawed design.
>> Please have a look here:
>> Since we are in a feature freeze in preparation for v2.16.0, I will
>> submit these patch series shortly after v2.16.0 is released.
>>> As far as I understand the root cause of this that when new merge
>>> commit is created by rebase it is done simply by git merge
>>> $new_parents without taking into account any actual state of the
>>> initial merge commit.
>> Indeed. preserve-merges does not allow commits to be reordered. (Actually,
>> it *does* allow it, but then fails to handle it correctly.) We even have
>> test cases that mark this as "known breakage".
>> But really, I do not think it is worth trying to fix the broken design.
>> Better to go with the new recreate-merges. (I am biased, of course,
>> because I invented recreate-merges. But then, I also invented
>> preserve-merges, so ...)
> Well. I just checked --recreate-merges=no-rebase-cousins from the PR
> and found that it produces the same wrong result in my test example.
> The topology is reproduced correctly, but merge-commit content is
> broken.
> I did git rebase --recreate-merges=no-rebase-cousins --onto abc-0.1 v0.1 abc-0.2

Indeed, exactly as you still say in the documentation: "Merge conflict
resolutions or manual amendments to merge commits are not preserved."
My initial point is that they have to be preserved. Probably in
recreate-merges, if preserve-merges is discontinued.

>> Ciao,
>> Johannes
> --
> With best regards,
> Matwey V. Kornilov

With best regards,
Matwey V. Kornilov

  reply	other threads:[~2018-01-08 14:46 UTC|newest]

Thread overview: 11+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-01-08 10:24 rebase preserve-merges: incorrect merge commits Matwey V. Kornilov
2018-01-08 13:56 ` Johannes Schindelin
2018-01-08 14:42   ` Matwey V. Kornilov
2018-01-08 14:46     ` Matwey V. Kornilov [this message]
2018-01-08 16:32       ` Johannes Schindelin
2018-01-08 17:24         ` Matwey V. Kornilov
2018-01-08 19:36           ` Johannes Schindelin
2018-01-09  9:49             ` Matwey V. Kornilov
2018-01-09 13:25               ` Johannes Schindelin
2018-01-09 14:19                 ` Matwey V. Kornilov
2018-01-09 16:29                   ` Johannes Schindelin

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