From: Duy Nguyen <pclouds@gmail.com>
Date: Tue, 19 Jan 2016 23:26:35 GMT
Subject: Re: Issue when changing staged files in a pre-commit hook
Message-ID: <CACsJy8DxQnGV5JZnHuvA1Zbpf2BuGdmMF+YNiq51HNK+8vW56Q@mail.gmail.com>
In-Reply-To: <xmqq1t9dbe9y.fsf@gitster.mtv.corp.google.com>

On Wed, Jan 20, 2016 at 1:44 AM, Junio C Hamano <gitster@pobox.com> wrote:
> Duy Nguyen <pclouds@gmail.com> writes:
>
>> I think it's the intended behavior.
>
> Yeah, pre-commit was designed for inspecting and rejecting, not for
> tweaking and munging.  Perhaps "git commit" can be tightened to make
> sure that pre-commit that returns successfully did not muck with the
> working tree and the index?

That was my impression from the docs, but then I saw this comment,

/*
* Re-read the index as pre-commit hook could have updated it,
* and write it out as a tree.  We must do this before we invoke
* the editor and after we invoke run_status above.
*/

which comes from 2888605 (builtin-commit: fix partial-commit support -
2007-11-18) that admits "the hook can modify it (the index)". And I
was about to update the docs, but the other way around, about updating
index and side effects.
-- 
Duy