2 files changed, 59 insertions, 1 deletions
diff --git a/builtin/apply.c b/builtin/apply.c
index 84f1863d3a..a1e20c593d 100644
--- a/builtin/apply.c
+++ b/builtin/apply.c
@@ -12,7 +12,7 @@ static const char * const apply_usage[] = {
 int cmd_apply(int argc,
 	      const char **argv,
 	      const char *prefix,
-	      struct repository *repo UNUSED)
+	      struct repository *repo)
 {
 	int force_apply = 0;
 	int options = 0;
@@ -35,6 +35,11 @@ int cmd_apply(int argc,
 				   &state, &force_apply, &options,
 				   apply_usage);
 
+	if (repo) {
+		prepare_repo_settings(repo);
+		repo->settings.command_requires_full_index = 0;
+	}
+
 	if (check_apply_state(&state, force_apply))
 		exit(128);
 
diff --git a/t/t1092-sparse-checkout-compatibility.sh b/t/t1092-sparse-checkout-compatibility.sh
index a4c7c41fc0..fa2472010d 100755
--- a/t/t1092-sparse-checkout-compatibility.sh
+++ b/t/t1092-sparse-checkout-compatibility.sh
@@ -1340,6 +1340,30 @@ test_expect_success 'submodule handling' '
 	grep "160000 $(git -C initial-repo rev-parse HEAD) 0	modules/sub" cache
 '
 
+test_expect_success 'git apply functionality' '
+	init_repos &&
+
+	test_all_match git checkout base &&
+
+	git -C full-checkout diff base..merge-right -- deep >patch-in-sparse &&
+	git -C full-checkout diff base..merge-right -- folder2 >patch-outside &&
+
+	# Apply a patch to a file inside the sparse definition
+	test_all_match git apply --index --stat ../patch-in-sparse &&
+	test_all_match git status --porcelain=v2 &&
+
+	# Apply a patch to a file outside the sparse definition
+	test_sparse_match test_must_fail git apply ../patch-outside &&
+	grep "No such file or directory" sparse-checkout-err &&
+
+	# But it works with --index and --cached
+	test_all_match git apply --index --stat ../patch-outside &&
+	test_all_match git status --porcelain=v2 &&
+	test_all_match git reset --hard &&
+	test_all_match git apply --cached --stat ../patch-outside &&
+	test_all_match git status --porcelain=v2
+'
+
 # When working with a sparse index, some commands will need to expand the
 # index to operate properly. If those commands also write the index back
 # to disk, they need to convert the index to sparse before writing.
@@ -2347,6 +2371,35 @@ test_expect_success 'sparse-index is not expanded: check-attr' '
 	ensure_not_expanded check-attr -a --cached -- folder1/a
 '
 
+test_expect_success 'sparse-index is not expanded: git apply' '
+	init_repos &&
+
+	git -C sparse-index checkout base &&
+	git -C full-checkout diff base..merge-right -- deep >patch-in-sparse &&
+	git -C full-checkout diff base..merge-right -- folder2 >patch-outside &&
+
+	# Apply a patch to a file inside the sparse definition
+	ensure_not_expanded apply --index --stat ../patch-in-sparse &&
+
+	# Apply a patch to a file outside the sparse definition
+	# Fails when caring about the worktree.
+	ensure_not_expanded ! apply ../patch-outside &&
+
+	# Expands when using --index.
+	ensure_expanded apply --index ../patch-outside &&
+
+	# Does not when index is partially expanded.
+	git -C sparse-index reset --hard &&
+	ensure_not_expanded apply --cached ../patch-outside &&
+
+	# Try again with a reset and collapsed index.
+	git -C sparse-index reset --hard &&
+	git -C sparse-index sparse-checkout reapply &&
+
+	# Expands when index is collapsed.
+	ensure_expanded apply --cached ../patch-outside
+'
+
 test_expect_success 'advice.sparseIndexExpanded' '
 	init_repos &&