Re: git submodule vs GIT_WORK_TREE

From: Junio C Hamano <gitster@pobox.com>
Date: Jun 26, 2012, 19:51 UTC
Message-ID: <7vobo5c0n0.fsf@alter.siamese.dyndns.org>
In-Reply-To: <4FE9FF0C.8050409@web.de>

Jens Lehmann <Jens.Lehmann@web.de> writes:

Show 17 quoted lines

> Am 26.06.2012 18:07, schrieb Junio C Hamano:
> ...
>> When the user exports GIT_WORK_TREE to tell git that the root of the
>> working tree the user wants to work on resides there (which is
>> needed when the user exports GIT_DIR to tell git that the user wants
>> to work on that repository), that wish obviously applies only to
>> that repository.  If git decides to visit the working tree of a
>> different repository (e.g. a checkout of a submodule bound to the
>> project GIT_WORK_TREE points at), even if it is done in response to
>> the user action (e.g. like passing "--recurse-submodules" option),
>> it should adjust GIT_WORK_TREE and GIT_DIR to be appropriate for
>> operations in the submodule repository while doing so.  If the more
>> recent "recursive" behaviour forgets to do so, it simply is a bug.
>
> I'm not sure what you mean by "appropriate for operations in the
> submodule repository". Should the submodule work tree be searched
> for under $GIT_WORK_TREE of the superproject or under $(pwd)?

I think either

 (1) unset GIT_WORK_TREE/GIT_DIR if the process chdirs to
     $GIT_WORK_TREE/submodule and $GIT_WORK_TREE/submodule/.git is
     the controlling reopsitory of that submodule working tree, or

 (2) set GIT_WORK_TREE/GIT_DIR to point at the working tree and
     repository of the submodule.

would be appropriate.

Show 5 quoted lines

> As far as I can see all submodule code consistently clears all
> environment variables used by git before descending into a
> submodule (at least since February 2010 and 5ce9086dd). Maybe we
> should change that so it sets the GIT_WORK_TREE environment to
> "$GIT_WORK_TREE/submodule" to be consistent?

If the user has to use GIT_WORK_TREE to mark the root level of the superproject working tree as such, it is very likely that the controlling repository of the superproject does not live in the $GIT_WORK_TREE/.git directory (in other words, $GIT_DIR points at somewhere else). Exporting GIT_WORK_TREE/submodule as the new value of GIT_WORK_TREE is sensible, but I do not see a reasonable way to deduce the value of GIT_DIR for the submodule in such a case. The controlling repository of the superproject is located somewhere random; there is no reason to assume the repository for the submodule is somewhere at fixed relation to it.

Does it mean the short answer to Richard's situation is "Don't do it"? I am not sure, but it is starting to sound like it.