Re: Need to change old commit (and regenerate tree)

From: Geert Uytterhoeven <geert@linux-m68k.org>
Date: May 21, 2010, 05:31 UTC
Message-ID: <AANLkTinzl_sc9G1PUtLczEjHFdpRqMFuKkEiQTUXaEgQ@mail.gmail.com>
In-Reply-To: <m2sk5mtecw.fsf@igel.home>

On Fri, May 21, 2010 at 00:09, Andreas Schwab <schwab@linux-m68k.org> wrote:

Show 15 quoted lines

> Antriksh Pany <antriksh.pany@gmail.com> writes:
>
>> Instead of (what I initially expected):
>>
>> A--------o--------o--------o--------o(old B)--------o--------o--------o(old C)
>>
>> A2--------o--------o--------o--------B--------o--------o--------C
>>
>>
>> So what I am missing here? Aren't the new commits B~1, B~2, B~3
>> identical to C~4, C~5, C~6 (respectively) in all ways so as to have
>> gotten them the same SHA1 and hence appear as what I expected them to
>> appear?
>
> No, they have a different commit time, which is also part of the hash.

Indeed.

To avoid this, you have to:
  - rebase B on top of A2 first,

        git rebase --onto A2 A B

  - rebase of C on top of the new B.

        git rebase --onto B B_old C
       ("git rebase --onto B A C" should work too, as usually git is
smart enough to see
        that A-B_old is already applied. Use "git rebase --skip" if it isn't)

If A is an ancestor of A2, you can simplify to:

    git rebase A2 B
    git rebase B C

(Disclaimer: the examples without --onto I use almost daily, the ones with I don't)

Gr{oetje,eeting}s,

						Geert

-- Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
							    -- Linus Torvalds