Merge branch 'sl/diff-tree-sparse'

"git diff-tree" has been taught to take advantage of the
sparse-index feature.

* sl/diff-tree-sparse:
  diff-tree: integrate with sparse index

Author: gitster

builtin/diff-tree.c

@@ -122,6 +122,10 @@ int cmd_diff_tree(int argc, const char **argv, const char *prefix)
 		usage(diff_tree_usage);
 
 	git_config(git_diff_basic_config, NULL); /* no "diff" UI options */
+
+	prepare_repo_settings(the_repository);
+	the_repository->settings.command_requires_full_index = 0;
+
 	repo_init_revisions(the_repository, opt, prefix);
 	if (repo_read_index(the_repository) < 0)
 		die(_("index file corrupt"));

t/perf/p2000-sparse-operations.sh

@@ -131,5 +131,7 @@ test_perf_on_all git describe --dirty
 test_perf_on_all 'echo >>new && git describe --dirty'
 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_done

t/t1092-sparse-checkout-compatibility.sh

@@ -2180,4 +2180,46 @@ test_expect_success 'sparse index is not expanded: diff-files' '
 	ensure_not_expanded diff-files -- "deep/*"
 '
 
+test_expect_success 'diff-tree' '
+	init_repos &&
+
+	# Test change inside sparse cone
+	tree1=$(git -C sparse-index rev-parse HEAD^{tree}) &&
+	tree2=$(git -C sparse-index rev-parse update-deep^{tree}) &&
+	test_all_match git diff-tree $tree1 $tree2 &&
+	test_all_match git diff-tree $tree1 $tree2 -- deep/a &&
+	test_all_match git diff-tree HEAD update-deep &&
+	test_all_match git diff-tree HEAD update-deep -- deep/a &&
+
+	# Test change outside sparse cone
+	tree3=$(git -C sparse-index rev-parse update-folder1^{tree}) &&
+	test_all_match git diff-tree $tree1 $tree3 &&
+	test_all_match git diff-tree $tree1 $tree3 -- folder1/a &&
+	test_all_match git diff-tree HEAD update-folder1 &&
+	test_all_match git diff-tree HEAD update-folder1 -- folder1/a &&
+
+	# Check that SKIP_WORKTREE files are not materialized
+	test_path_is_missing sparse-checkout/folder1/a &&
+	test_path_is_missing sparse-index/folder1/a &&
+	test_path_is_missing sparse-checkout/folder2/a &&
+	test_path_is_missing sparse-index/folder2/a
+'
+
+test_expect_success 'sparse-index is not expanded: diff-tree' '
+	init_repos &&
+
+	tree1=$(git -C sparse-index rev-parse HEAD^{tree}) &&
+	tree2=$(git -C sparse-index rev-parse update-deep^{tree}) &&
+	tree3=$(git -C sparse-index rev-parse update-folder1^{tree}) &&
+
+	ensure_not_expanded diff-tree $tree1 $tree2 &&
+	ensure_not_expanded diff-tree $tree1 $tree2 -- deep/a &&
+	ensure_not_expanded diff-tree HEAD update-deep &&
+	ensure_not_expanded diff-tree HEAD update-deep -- deep/a &&
+	ensure_not_expanded diff-tree $tree1 $tree3 &&
+	ensure_not_expanded diff-tree $tree1 $tree3 -- folder1/a &&
+	ensure_not_expanded diff-tree HEAD update-folder1 &&
+	ensure_not_expanded diff-tree HEAD update-folder1 -- folder1/a
+'
+
 test_done