Re: [PATCH v2 0/1] Make 'git commit' not accidentally lose staged content

From: Jacob Keller <jacob.keller@gmail.com>
Date: Sep 18, 2018, 19:33 UTC
Message-ID: <CA+P7+xoJ9URXxD=+uqfeqWmscec6=LnUTse_CcVi2z=91Rw=Tw@mail.gmail.com>
In-Reply-To: <xmqq1s9s82zx.fsf@gitster-ct.c.googlers.com>

On Mon, Sep 17, 2018 at 10:09 AM Junio C Hamano <gitster@pobox.com> wrote:

>
> It usually is safer (simply because you do not have to think about
> it) to start a behaviour change like this as a strict opt-in to gain
> confidence.

I tend to agree, however.. in this case it could be considered safer to err on the side of not throwing away the index which could have crafted changes in it.

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> The approach to check if the contents in the index matches that in
> the HEAD per-path (i.e. "The contents we are adding to the index is
> whole working tree contents for that path.  But the index already
> has contents different from HEAD for the path---are we losing
> information by doing this?"), is a very good one.  But for the
> protection to be effective, I think "git commit" and "git add"
> should be covered the same way, ideally with the same code and
> possibly the same configuration knob and/or command line option to
> control the behaviour.

Checking both commit and add makes sense to me.

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>
> If the information loss caused by the "add/commit X" or "add
> -u/commit -a" is so serious that this new feature deserves to become
> the default (which I do not yet think it is the case, by the way),
> then we could even forbid "commit X" or "commit -a" when the paths
> involved has difference between the index and the HEAD, without any
> configuration knob or command line override for "commit", and then
> tell the users to use "git add/rm" _with_ the override before coming
> back to "git commit".

I was going to suggest we have some sort of reflog equivalent for the index, but Duy seems to discuss that in a follow-on mail.

>
> How should this new check intract with paths added with "add -N", by
> the way?