Merge branch 'sl/worktree-sparse'

"git worktree" learned to work better with sparse index feature.

* sl/worktree-sparse:
  worktree: integrate with sparse-index

builtin/worktree.c

@@ -1407,5 +1407,9 @@ int cmd_worktree(int ac, const char **av, const char *prefix)
 		prefix = "";
 
 	ac = parse_options(ac, av, prefix, options, git_worktree_usage, 0);
+
+	prepare_repo_settings(the_repository);
+	the_repository->settings.command_requires_full_index = 0;
+
 	return fn(ac, av, prefix);
 }

t/perf/p2000-sparse-operations.sh

@@ -133,5 +133,6 @@ test_perf_on_all git diff-files
 test_perf_on_all git diff-files -- $SPARSE_CONE/a
 test_perf_on_all git diff-tree HEAD
 test_perf_on_all git diff-tree HEAD -- $SPARSE_CONE/a
+test_perf_on_all "git worktree add ../temp && git worktree remove ../temp"
 
 test_done

t/t1092-sparse-checkout-compatibility.sh

@@ -2222,4 +2222,41 @@ test_expect_success 'sparse-index is not expanded: diff-tree' '
 	ensure_not_expanded diff-tree HEAD update-folder1 -- folder1/a
 '
 
+test_expect_success 'worktree' '
+	init_repos &&
+
+	write_script edit-contents <<-\EOF &&
+	echo text >>"$1"
+	EOF
+
+	for repo in full-checkout sparse-checkout sparse-index
+	do
+		worktree=${repo}-wt &&
+		git -C $repo worktree add ../$worktree &&
+
+		# Compare worktree content with "ls"
+		(cd $repo && ls) >worktree_contents &&
+		(cd $worktree && ls) >new_worktree_contents &&
+		test_cmp worktree_contents new_worktree_contents &&
+
+		# Compare index content with "ls-files --sparse"
+		git -C $repo ls-files --sparse >index_contents &&
+		git -C $worktree ls-files --sparse >new_index_contents &&
+		test_cmp index_contents new_index_contents &&
+
+		git -C $repo worktree remove ../$worktree || return 1
+	done &&
+
+	test_all_match git worktree add .worktrees/hotfix &&
+	run_on_all ../edit-contents .worktrees/hotfix/deep/a &&
+	test_all_match test_must_fail git worktree remove .worktrees/hotfix
+'
+
+test_expect_success 'worktree is not expanded' '
+	init_repos &&
+
+	ensure_not_expanded worktree add .worktrees/hotfix &&
+	ensure_not_expanded worktree remove .worktrees/hotfix
+'
+
 test_done