Subject: Re: git submodule vs GIT_WORK_TREE

From: Jens Lehmann <[email-masked]>
Date: Tue, 26 Jun 2012 20:27:24 +0200

Am 26.06.2012 18:07, schrieb Junio C Hamano:
> Richard Hartmann <[email-masked]> writes:
> 
>> As you are most likely aware, `git submodule` allows you to access a
>> separate git repository in a sub-directory, e.g. $submodule, while
>> $GIT_WORK_TREE forces git to operate in a specific directory. Combine
>> the two and the result is less than ideal. git is forced to operate in
>> $GIT_WORK_TREE while it should operate on $GIT_WORK_TREE/$submodule,
>> instead.

Richard, could you please tell us what git commands behave strange
in what way and what your expectations were? A short test shows e.g.
"git submodule foreach" operates on $(pwd)/submodule even though
GIT_WORK_TREE is set while at the same time git status shows the same
submodule as missing because it is looking for it in $GIT_WORK_TREE.
Is that what you are talking about?

> The end user should not be asked to anything special.
> 
> 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)?

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?