Re: rev-parse --show-toplevel broken during exec'ed rebase?

From: Johannes Schindelin <johannes.schindelin@gmx.de>
Date: Jul 12, 2018, 15:02 UTC
Message-ID: <nycvar.QRO.7.76.6.1807121657120.75@tvgsbejvaqbjf.bet>
In-Reply-To: <nycvar.QRO.7.76.6.1807121647310.75@tvgsbejvaqbjf.bet>

Hi,

On Thu, 12 Jul 2018, Johannes Schindelin wrote:

Show 33 quoted lines

> On Wed, 11 Jul 2018, Vitali Lovich wrote:
> 
> > On Wed, Jul 11, 2018 at 7:50 PM Vitali Lovich <vlovich@gmail.com> wrote:
> > >
> > > Typically git rev-parse --show-toplevel prints the folder containing
> > > the .git folder regardless what subdirectory one is in.  One exception
> > > I have found is that if one is within the context of git rebase --exec
> > > then show-toplevel always just prints the current directory it's
> > > running from.
> > >
> > > Repro (starting with cwd within git project):
> > > > (cd xdiff; git rev-parse --show-toplevel)
> > > ... path to git repository
> > > > git rebase -i 18404434bf406f6a6f892ed73320c5cf9cc187dd
> > > # Stop at some commit for editing
> > > > (cd xdiff; git rev-parse --show-toplevel)
> > > ... path to git repository
> > > > git rebase 18404434bf406f6a6f892ed73320c5cf9cc187dd -x "(cd xdiff; git rev-parse --show-toplevel)"
> > > ... path to git repository/xdiff !!!
> > >
> > > This seems like incorrect behaviour to me since it's a weird
> > > inconsistency (even with other rebase contexts) & the documentation
> > > says "Show the absolute path of the top-level directory." with no
> > > caveats.
> >
> > Sorry.  Forgot to include the git versions I tested with (2.13.1,
> > 2.17.0, 2.18.0)
> 
> This is actually not so much a bug in `rebase` as in `rev-parse
> --show-top-level`:
> 
> 	$ GIT_DIR=$PWD/.git git -C xdiff rev-parse --show-toplevel
> 	C:/git-sdk-64/usr/src/git/xdiff

And the reason for this behavior is that setting `GIT_DIR` explicitly makes Git *always* consider the current working directory to be the top-level directory:

	https://github.com/git/git/blob/v2.18.0/setup.c#L1061-L1063

I wonder whether changing the line (https://github.com/git/git/blob/v2.18.0/sequencer.c#L2635)

   argv_array_pushf(&child_env, "GIT_DIR=%s", absolute_path(get_git_dir()));

to

   argv_array_push(&child_env, "GIT_DIR");

breaks anything (and whether it fixes the bug you demonstrated via `rev-parse --show-toplevel`).

Ciao, Johannes