Merge branch 'sl/sparse-write-tree'

"git write-tree" learns to work better with sparse-index.

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

builtin/write-tree.c

@@ -41,6 +41,9 @@ int cmd_write_tree(int argc, const char **argv, const char *cmd_prefix)
 	argc = parse_options(argc, argv, cmd_prefix, write_tree_options,
 			     write_tree_usage, 0);
 
+	prepare_repo_settings(the_repository);
+	the_repository->settings.command_requires_full_index = 0;
+
 	ret = write_index_as_tree(&oid, &the_index, get_index_file(), flags,
 				  tree_prefix);
 	switch (ret) {

t/perf/p2000-sparse-operations.sh

@@ -125,5 +125,6 @@ test_perf_on_all git checkout-index -f --all
 test_perf_on_all git update-index --add --remove $SPARSE_CONE/a
 test_perf_on_all "git rm -f $SPARSE_CONE/a && git checkout HEAD -- $SPARSE_CONE/a"
 test_perf_on_all git grep --cached bogus -- "f2/f1/f1/*"
+test_perf_on_all git write-tree
 
 test_done

t/t1092-sparse-checkout-compatibility.sh

@@ -2055,4 +2055,32 @@ test_expect_success 'grep sparse directory within submodules' '
 	test_cmp actual expect
 '
 
+test_expect_success 'write-tree on all' '
+	init_repos &&
+
+	write_script edit-contents <<-\EOF &&
+	echo text >>"$1"
+	EOF
+
+	run_on_all ../edit-contents deep/a &&
+	run_on_all git update-index deep/a &&
+	test_all_match git write-tree &&
+
+	run_on_all mkdir -p folder1 &&
+	run_on_all cp a folder1/a &&
+	run_on_all ../edit-contents folder1/a &&
+	run_on_all git update-index folder1/a &&
+	test_all_match git write-tree
+'
+
+test_expect_success 'sparse-index is not expanded: write-tree' '
+	init_repos &&
+
+	ensure_not_expanded write-tree &&
+
+	echo "test1" >>sparse-index/a &&
+	git -C sparse-index update-index a &&
+	ensure_not_expanded write-tree
+'
+
 test_done