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From:   Junio C Hamano <gitster@pobox.com>
To:     Elijah Newren <newren@gmail.com>
Cc:     Jonathan Nieder <jrnieder@gmail.com>,
        Johannes Schindelin <Johannes.Schindelin@gmx.de>,
        Phillip Wood <phillip.wood@dunelm.org.uk>,
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        SZEDER =?utf-8?Q?G=C3=A1bor?= <szeder.dev@gmail.com>
Subject: Re: [PATCH v3 15/15] rebase: change the default backend from "am" to "merge"
References: <pull.679.v3.git.git.1577217299.gitgitgadget@gmail.com>
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Date:   Thu, 16 Jan 2020 15:25:52 -0800
In-Reply-To: <CABPp-BHiYDLRgPX4A1-8f-zgfsDqf6PkToStaV3ukC5Dsq=3-w@mail.gmail.com>
        (Elijah Newren's message of "Thu, 16 Jan 2020 13:30:38 -0800")
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Elijah Newren <newren@gmail.com> writes:

> Why?  "Commands which create no more than one commit (git-commit,
> git-merge, maybe single-commit git-revert or git-cherry-pick) call
> post-commit, commands which create several commits derived from others
> (git-am, git-rebase, git-cherry-pick, sometimes git-revert ) call
> post-rewrite instead for performance reasons"

Sounds totally wrong.  post-rewrite is about carrying forward data
that used to be associated with commit X to new commit Y when Y was
created by "rewriting" X (i.e. after Y gets created X no longer has
any purpose other than as a historical curiosity).  There is nothing
"for performance reasons" here.  There should be nothing for "git
revert" to do with post-rewrite (because the resulting commit is not
even a rewrite of the commit that was reverted), and "git
cherry-pick" is not even a rewrite operation (it is to duplicate an
existing commit into another unrelated context, without discarding
the original commit).

I am a bit confused...