Re: gitconfig get out of sync with submodule entries on branch switch

[Brandon Williams <bmwill@google.com>]

On 01/30, Benjamin Schindler wrote:
> Hi
> 
> Consider the following usecase: I have the master branch where I
> have a submodule A. I create a branch where I rename the submodule
> to be in the directory B. After doing all of this, everything looks
> good.
> Now, I switch back to master. The first oddity is, that it fails to
> remove the folder B because there are still files in there:
> 
> bschindler@metis ~/Projects/submodule_test (testbranch) $ git
> checkout master
> warning: unable to rmdir other_submodule: Directory not empty
> Switched to branch 'master'
> 
> Git submodule deinit on B fails because the submodule is not known
> to git anymore (after all, the folder B exists only in the other
> branch). I can easily just remove the folder B from disk and
> initialize the submodule A again, so all seems good.
> 
> However, what is not good is that the submodule b is still known in
> .git/config. This is in particular a problem for us, because I know
> a number of tools which use git config to retrieve the submodule
> list. Is it therefore a bug that upon branch switch, the submodule
> gets deregistered, but its entry in .git/config remains?
> 
> thanks a lot
> Benjamin Schindler
> 
> P.s. I did not subscribe to the mailing list, please add me at least
> do CC. Thanks

submodules and checkout don't really play nicely with each other at the
moment.  Stefan (cc'd) is currently working on a patch series to improve
the behavior of checkout with submodules.  Currently, if you want to
ensure you have a good working state after a checkout you should run
`git submodule update` to update all of the submoules.  As far as your
submodule still being listed in the config, that should be expected
given the scenario you described.

If I'm understanding you correctly, A and B are both the same submodule
just renamed on a different branch.  The moment you add a submoule to a
repository it is given a name which is fixed.  Typically this is the
path from the root of the repository.  The thing is, since you are able
to freely move a submodule, its path can change.  To account for this
there is the .gitmodules file which allows you to do a lookup from
submodule name to the path at which it exists (or vice versa).  The
submodules that are stored in .git/config are those which are
'initialize' or rather the submodules in which you are interested in and
will be updated by `git submodule update`.  So given your scenario you
should only have a single submodule in .git/config and the .gitmodules
file should have a single entry with a differing path for each branch.

Hopefully this gives you a bit more information to work with.  Since
Stefan has been working with this more recently than me he may have some
more input.

-- 
Brandon Williams