Re: Editing the root commit

From: Junio C Hamano <gitster@pobox.com>
Date: Jun 20, 2012, 18:25 UTC
Message-ID: <7vy5nhvo0z.fsf@alter.siamese.dyndns.org>
In-Reply-To: <20120620093205.GB10579@arachsys.com>

Chris Webb <chris@arachsys.com> writes:

Show 23 quoted lines

> Chris Webb <chris@arachsys.com> writes:
>
>> Junio C Hamano <gitster@pobox.com> writes:
>>
>> > Even though I wouldn't bother doing this myself, I wouldn't mind
>> > reviewing a patch series ;-)
>> 
>> Okay, I'll take a look when I finish my current project!
>
> I had a bit of spare time this morning and had a quick look through
> git-rebase--interactive.sh.
>
> Apart from the validation, message and reflog code in git-rebase.sh and
> git-rebase--interactive.sh that would need fixing up to know about this
> case, the essence of this seems to be starting with an orphan commit instead
> of a commit descended from $onto right at the end of --interactive.
>
> I'd love to write something like
>
>   git checkout ${onto:---orphan}
>
> (or a variant) but can git be persuaded to have an orphan detached HEAD like
> that?

For the root commit in the history, you check it out on the detached HEAD. Under "--interactive" if the insn sheet tells you to allow the user to "edit/amend/reword" it, give control back the user after you have detached HEAD at that commit. The user experience should be identical to the case you are replaying on an existing commit after that point.

But lets step back a bit and look at the whole picture, to make sure we are on the same page.

    $ git rebase [-i] frotz

looks at where you are, finds where you forked from 'frotz', and replays everything you have done since you forked onto the tip of 'frotz'.

    $ git rebase [-i] --onto nitfol frotz

replays the same history onto the tip of 'nitfol' instead.

    $ git rebase [-i] --root --onto nitfol

looks at the entire history leading to where you are, and replays everything you have done onto the tip of 'nitfol'.

What if we do not say --onto here? I am not asking what the current implementation does (we get an error message saying "I want 'onto' specified"). What _should_ this command mean to a naïve user?

    $ git rebase [-i] --root

I think it should mean "replay all my history down to root". The original root commit should become the new root commit in the rewritten history.