Re: How to merge by subtree while preserving history?

From: Miklos Vajna <vmiklos@frugalware.org>
Date: Mar 27, 2009, 07:38 UTC
Message-ID: <20090327073847.GE27459@genesis.frugalware.org>
In-Reply-To: <A5C2B218-4E4F-4C05-959D-5B6E9C619DDB@gmail.com>

On Thu, Mar 26, 2009 at 06:59:51PM -0400, David Reitter <david.reitter@gmail.com> wrote:

Show 6 quoted lines

> I have two separately developed projects (foo, bar) which I'd like to  
> merge; the contents of foo should, initially, go in a subdirectory of  
> bar.
> 
> I'm aware of two methods:  moving (renaming) everything within foo  
> into foo-dir, and then just pulling foo into bar.

The result of the two methods are the same.

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> This works beautifully, except that the big rename causes havoc w.r.t.  
> to the files histories, i.e. git-log needs a "--follow" argument now,  
> and "diff-tree" can't track changes when given the new file name.  No  
> good.
> 
> I've also tried the method described in [1], but it seems that all  
> history is lost here (the text could point this out..)

Of course it is not lost. :)

Example:

commit f8c62880ef22b74ea6df47bb349ff0743d2a93f9
Merge: f474c52... 52b8ea9...
Author: Junio C Hamano <gitster@pobox.com>
Date:   Sun Mar 1 22:20:52 2009 -0800

    Merge git://git.kernel.org/pub/scm/gitk/gitk

Now do a 'git log f474c52..52b8ea9' and you'll see the merged commits.

But you are right about that 'git log -- path' will find the merge commits only (which is right, as the tree objects are not modified when merging, just the resulting tree has the original tree in a subdirectory).

If this is a one-time operation then I would just use git filter-branch to move the code to a subdir.