Re: detecting rename->commit->modify->commit

From: Avery Pennarun <apenwarr@gmail.com>
Date: May 1, 2008, 15:50 UTC
Message-ID: <32541b130805010850q165fe1d6me05e670ca93b0892@mail.gmail.com>
In-Reply-To: <20080501153457.GB11469@sigill.intra.peff.net>

On 5/1/08, Jeff King <peff@peff.net> wrote:

Show 23 quoted lines

> On Thu, May 01, 2008 at 11:27:34AM -0400, Avery Pennarun wrote:
>
>  > Before you say this is not a realistic use case, I've personally had
>  > this exact problem:
>  >
>  > - I had a project with all of my work in a folder "src"
>  > - I decided that the 'src' folder was redundant, so I moved it all to
>  > the root folder
>  > - Someone else was working on an old maintenance branch which still had 'src'
>  > - When I merged from that person, some new files were created under
>  > 'src', and of course didn't work.
>
>
> Sure. But we've also had the exact case of:
>
>   - there are some files in subdir/ [1], but that is not a good name, and
>     there is something else that you are going to add that would be
>     better named as subdir/.
>   - you rename subdir/ to bettername/ [2]
>   - you create subdir/newfile [3]
>
>  but you _don't_ want newfile to go into bettername/. It's _replacing_
>  what went into bettername/.

I would argue that this is a sort of "directory splitting" operation. That is, all anyone ever did was add some files to a subdir/ that already existed [1], *or* move all the files from subdir/ to a previously-empty bettername/ [2], *or* create a new subdir/ and add files to it [3]. In each case, no merge operation was necessary and it is completely obvious by comparing "before and after" trees which case it was.

I guess my argument here is just that it should be *possible* to deduce and implement both cases at merge time just fine using git's existing storage model. It just hasn't been implemented yet. (And incidentally, I think that's totally awesome and I'd never want to go back to an explicit rename tracking model.)

I should shut up now because the actual merge machinery scares me and I'm not willing to volunteer to write a patch for this one :)

Have fun,

Avery