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From: Junio C Hamano <gitster@pobox•com>
To: Shawn Pearce <spearce@spearce•org>
Cc: git <git@vger•kernel.org>
Subject: Re: git commit --amend safety check?
Date: Tue, 10 Mar 2015 22:11:43 -0700	[thread overview]
Message-ID: <xmqq8uf46ru8.fsf@gitster.dls.corp.google.com> (raw)
In-Reply-To: <CAJo=hJuwdOzNZSVBRAPDz97Gdoi6JWvYxE0ufY+Hd9K8jjCqfA@mail.gmail.com> (Shawn Pearce's message of "Tue, 10 Mar 2015 21:31:40 -0700")

Shawn Pearce <spearce@spearce•org> writes:

> We keep seeing reports of Gerrit Code Review users who incorrectly do
> something like:
>
>   git clone URL foo
>   cd foo
>   git commit --amend -m "My first change!" -a
>   git push URL HEAD:refs/for/master
>
> Step #3 is where they get into trouble. They just amended the
> published tip commit and pushed it back to the server. That is... lets
> just say not good.
>
> Hg is known to be more user friendly. One way its user friendly is it
> by default refuses to let you amend a change set that the client has
> reasonable assertion to believe was already published through a remote
> repository.

Well, it is not Git that is less user friendly, but Gerrit is the
problem.  More specifically, the last line:

>   git push URL HEAD:refs/for/master

is what catches this non-fast-forward in usual workflow with Git.
Wouldn't the real problem that the refs/for/master magic accepts
anything, even a non-fast-forward?

Having said that, disabling --amend and forcing to use --force or
something when it is clear that the user is attempting something
unusual is a good idea.  But I am not sure what the definition of
unusual should be.  In a non-Gerrit central repository workflow, the
rule might be "HEAD must not be reachable from @{upstream}"
(otherwise you are rewriting what you got from elsewhere), or it may
be "HEAD must not be reachable from @{publish}'s remote tracking
branch", or perhaps both, as these two could be different in
triangular workflow.

But I am not sure what the sensible rules are when the user prepares
the commit, planning to push it to a ref like refs/for/master that
does not have a counterpart on our side.

  reply	other threads:[~2015-03-11  5:11 UTC|newest]

Thread overview: 8+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2015-03-11  4:31 git commit --amend safety check? Shawn Pearce
2015-03-11  5:11 ` Junio C Hamano [this message]
2015-03-11  6:00   ` Shawn Pearce
2015-03-11  6:18     ` Junio C Hamano
2015-03-11  6:33       ` Mike Hommey
2015-03-11  8:13       ` Jeff King
2015-03-11  8:37   ` Peter Krefting
2015-03-11 17:56     ` Junio C Hamano

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