Subject: Re: [PATCH] setup: set env $GIT_WORK_TREE when work tree is set, like $GIT_DIR

From: Junio C Hamano <[email-masked]>
Date: Fri, 26 Jun 2015 10:30:28 -0700

Nguyễn Thái Ngọc Duy  <[email-masked]> writes:

> This is where the "fun" is. The legacy behavior is, if $GIT_WORK_TREE is
> not set but $GIT_DIR is, cwd is chosen as worktree's top. If you happen
> to stand at worktree's top when you do this, all is well.

It is not legacy, though.  It is how things were designed to be
used, and how things are supposed to work in the future.

Until we do the deprecation dance to force people to update existing
scripts to explicitly export GIT_WORK_TREE=$(pwd) or something like
that, that is.

And I wouldn't be opposed to such a transition plan; something along
the lines of what Peff outlined in that old thread.

http://thread.gmane.org/gmane.comp.version-control.git/219096/focus=219197

> Bottom line is, when $GIT_DIR is set, $GIT_WORK_TREE should be set too
> unless there's no work tree. But setting $GIT_WORK_TREE inside
> set_git_dir() may backfire. We don't know at that point if work tree is
> already configured by the caller. So set it when work tree is
> detected. It does not harm if $GIT_WORK_TREE is set while $GIT_DIR is
> not.

I am inclined to queue this on 'next' per "experimental" basis so
that other people with different workflows (especially those who
use existing scripts around Git plumbing heavily) can see if this
does not have any unintended fallouts.  I cannot convince myself
that it is generally a safe thing to do to muck with environment
partially, hoping nobody would care.

Thanks for looking into it.

>  environment.c      |  2 ++
>  t/t0002-gitfile.sh | 17 +++++++++++++++++
>  2 files changed, 19 insertions(+)
>
> diff --git a/environment.c b/environment.c
> index 61c685b..8f1b249 100644
> --- a/environment.c
> +++ b/environment.c
> @@ -231,6 +231,8 @@ void set_git_work_tree(const char *new_work_tree)
>  	}
>  	git_work_tree_initialized = 1;
>  	work_tree = xstrdup(real_path(new_work_tree));
> +	if (setenv(GIT_WORK_TREE_ENVIRONMENT, work_tree, 1))
> +		error("Could not set GIT_WORK_TREE to '%s'", work_tree);
>  }
>  
>  const char *get_git_work_tree(void)
> diff --git a/t/t0002-gitfile.sh b/t/t0002-gitfile.sh
> index 37e9396..9393322 100755
> --- a/t/t0002-gitfile.sh
> +++ b/t/t0002-gitfile.sh
> @@ -99,4 +99,21 @@ test_expect_success 'check rev-list' '
>  	test "$SHA" = "$(git rev-list HEAD)"
>  '
>  
> +test_expect_success 'setup_git_dir twice in subdir' '
> +	git init sgd &&
> +	(
> +		cd sgd &&
> +		git config alias.lsfi ls-files &&
> +		mv .git .realgit &&
> +		echo "gitdir: .realgit" >.git &&
> +		mkdir subdir &&
> +		cd subdir &&
> +		>foo &&
> +		git add foo &&
> +		git lsfi >actual &&
> +		echo foo >expected &&
> +		test_cmp expected actual
> +	)
> +'
> +
>  test_done