Subject: Re: [PATCH 1/2] t1092: test 'git restore' with sparse index

From: Junio C Hamano <[email-masked]>
Date: Mon, 25 May 2026 07:51:31 +0900

"Derrick Stolee via GitGitGadget" <[email-masked]> writes:

> From: Derrick Stolee <[email-masked]>
>
> A user reported that 'git restore --staged .' causes the sparse index to
> expand. This is somewhat natural because the '.' pathspec means 'check
> every path'. However, the restore will not update paths marked with the
> SKIP_WORKTREE bit, so we shouldn't need to process such entries.

Interesting.  So, ideally we should be able to say "we are doing
everything because the user gave us '.' from the top level of the
working tree, so let's see each entry and decide what to do.  Ah we
have this tree entry in this sparse index, and that is outside the
directories we are dealing with in this working tree that is
sparsely checked out, so we would skip", and for that we have no
need to expand the index.  But in reality, what happens is "OK, '.'
so we need to deal with everything. Let's expand.", which would
break the contents of such a "skipped" tree out to constituent
paths, all of which inherits the SKIP_WORKTREE bit to tell us that
these paths are outside the directories we are dealing with".

The end result in the working tree should be the same, but we
unnecessarily expand the index.  Correctness wins with a room for
improvement in the performance, which is what we want to see and
then improve ;-)  Nice.

> For now, establish the current behavior, including the sparse index
> expansion, in the t1092 test case as a baseline.
>
> Signed-off-by: Derrick Stolee <[email-masked]>
> ---
>  t/t1092-sparse-checkout-compatibility.sh | 50 ++++++++++++++++++++++++
>  1 file changed, 50 insertions(+)
>
> diff --git a/t/t1092-sparse-checkout-compatibility.sh b/t/t1092-sparse-checkout-compatibility.sh
> index d98cb4ac11..d69434e7ab 100755
> --- a/t/t1092-sparse-checkout-compatibility.sh
> +++ b/t/t1092-sparse-checkout-compatibility.sh
> @@ -2573,4 +2573,54 @@ test_expect_success 'sparse-index is not expanded: merge-ours' '
>  	ensure_not_expanded merge -s ours merge-right
>  '
>  
> +test_expect_success 'restore --staged with sparse definition' '
> +	init_repos &&
> +
> +	# Stage changes within the sparse definition
> +	test_all_match git checkout -b restore-staged-1 base &&
> +	test_all_match git reset --soft update-deep &&
> +	test_all_match git restore --staged . &&
> +	test_all_match git status --porcelain=v2 &&
> +	test_all_match git diff --cached
> +'
> +
> +test_expect_success 'restore --staged with outside sparse definition' '
> +	init_repos &&
> +
> +	# Stage changes that include paths outside the sparse definition.
> +	# Although the working tree differs between full and sparse checkouts
> +	# after restore, the state of the index should be the same.
> +	test_all_match git checkout -b restore-staged-2 base &&
> +	test_all_match git reset --soft update-folder1 &&
> +	test_sparse_match git restore --staged . &&
> +	git -C full-checkout restore --staged . &&
> +	test_all_match git ls-files -s -- folder1 &&
> +	test_all_match git diff --cached -- folder1
> +'
> +
> +test_expect_success 'restore --staged with wildcards' '
> +	init_repos &&
> +
> +	test_all_match git checkout -b restore-staged-3 base &&
> +	test_all_match git reset --soft update-deep &&
> +	test_all_match git restore --staged "deep/*" &&
> +	test_all_match git status --porcelain=v2 &&
> +	test_all_match git diff --cached
> +'
> +
> +test_expect_success 'sparse-index is expanded: restore --staged' '
> +	init_repos &&
> +
> +	git -C sparse-index checkout -b restore-staged-exp base &&
> +	git -C sparse-index reset --soft update-folder1 &&
> +	ensure_expanded restore --staged .
> +'
> +
> +test_expect_success 'sparse-index is expanded: restore --source --staged' '
> +	init_repos &&
> +
> +	git -C sparse-index checkout -b restore-source-staged base &&
> +	ensure_expanded restore --source update-folder1 --staged .
> +'
> +
>  test_done