Re: Track git blame through two unrelated histories

From: Ilia Pozhilov <ilyapoz@gmail.com>
Date: Mar 13, 2023, 11:48 UTC
Message-ID: <CAAo-ADbDW3WCuRFCnNopg31B_hDumz5qVOzirczG70odSVa6Bw@mail.gmail.com>
In-Reply-To: <xmqqwn3pai2d.fsf@gitster.g>

Track git blame through two unrelated histories

Inbox Ilia Pozhilov Thu, Mar 9, 1:05 PM (4 days ago) Hello! I have a weird use case. A repository at my company was migrated git -> non-git vcs -> git again. During transition to non-git vcs the history was lost,

Junio C Hamano <gitster@pobox.com>

Thu, Mar 9, 8:35 PM (4 days ago)

to me, git Ilia Pozhilov <ilyapoz@gmail.com> writes:

Show 9 quoted lines

> So let's say I add two remotes and fetch all the commits, but they
> look like this:
>
> A->B-> .... . . . -> Z    history1
>
> 1 -> 2 -> ..... -> 0 history2
>
> and file contents in commits Z and 1 are exactly the same, but the
> commits themselves are completely unrelated for git.

You mean you want to pretend that history "2 -> ... -> 0" was built on top of Z? Here I am assuming that time flows from left to right in the picture.

If so, you should be able to graft the histories together, perhaps?

Totally untested but something like

        $ git replace --graft 1 Z

based on my reading of "git help replace" should allow you to pretend that Z happened immediately before 1.

Junio C Hamano (gitster@pobox.com), git@vger.kernel.org Plain text

Ilia Pozhilov <ilyapoz@gmail.com>

Fri, Mar 10, 6:32 PM (3 days ago)

to Junio Thank you very much for this! It worked, I found the corresponding commits and did exactly as you suggested. Now blames just work!

Now I will need to figure out if this is push'able to github, but even at this stage it's incredibly useful, I love blames!

On Thu, Mar 9, 2023 at 8:35 PM Junio C Hamano <gitster@pobox.com> wrote:

Show 26 quoted lines

>
> Ilia Pozhilov <ilyapoz@gmail.com> writes:
>
> > So let's say I add two remotes and fetch all the commits, but they
> > look like this:
> >
> > A->B-> .... . . . -> Z    history1
> >
> > 1 -> 2 -> ..... -> 0 history2
> >
> > and file contents in commits Z and 1 are exactly the same, but the
> > commits themselves are completely unrelated for git.
>
> You mean you want to pretend that history "2 -> ... -> 0" was built
> on top of Z?  Here I am assuming that time flows from left to right
> in the picture.
>
> If so, you should be able to graft the histories together, perhaps?
>
> Totally untested but something like
>
>         $ git replace --graft 1 Z
>
> based on my reading of "git help replace" should allow you to
> pretend that Z happened immediately before 1.
>