Merge branch 'mh/status-optionally-refresh' into maint

* mh/status-optionally-refresh:
  t7508: add a test for "git status" in a read-only repository
  git status: refresh the index if possible
  t7508: add test for "git status" refreshing the index

builtin/commit.c

@@ -1017,6 +1017,7 @@ static int git_status_config(const char *k, const char *v, void *cb)
 int cmd_status(int argc, const char **argv, const char *prefix)
 {
 	struct wt_status s;
+	int fd;
 	unsigned char sha1[20];
 	static struct option builtin_status_options[] = {
 		OPT__VERBOSE(&verbose),
@@ -1050,6 +1051,14 @@ int cmd_status(int argc, const char **argv, const char *prefix)
 
 	read_cache_preload(s.pathspec);
 	refresh_index(&the_index, REFRESH_QUIET|REFRESH_UNMERGED, s.pathspec, NULL, NULL);
+
+	fd = hold_locked_index(&index_lock, 0);
+	if (0 <= fd) {
+		if (!write_cache(fd, active_cache, active_nr))
+			commit_locked_index(&index_lock);
+		rollback_lock_file(&index_lock);
+	}
+
 	s.is_initial = get_sha1(s.reference, sha1) ? 1 : 0;
 	s.in_merge = in_merge;
 	wt_status_collect(&s);

t/t7508-status.sh

@@ -496,6 +496,16 @@ test_expect_success 'dry-run of partial commit excluding new file in index' '
 	test_cmp expect output
 '
 
+cat >expect <<EOF
+:100644 100644 e69de29bb2d1d6434b8b29ae775ad8c2e48c5391 0000000000000000000000000000000000000000 M	dir1/modified
+EOF
+test_expect_success 'status refreshes the index' '
+	touch dir2/added &&
+	git status &&
+	git diff-files >output &&
+	test_cmp expect output
+'
+
 test_expect_success 'setup status submodule summary' '
 	test_create_repo sm && (
 		cd sm &&
@@ -693,4 +703,19 @@ test_expect_success 'commit --dry-run submodule summary (--amend)' '
 	test_cmp expect output
 '
 
+test_expect_success POSIXPERM 'status succeeds in a read-only repository' '
+	(
+		chmod a-w .git &&
+		# make dir1/tracked stat-dirty
+		>dir1/tracked1 && mv -f dir1/tracked1 dir1/tracked &&
+		git status -s >output &&
+		! grep dir1/tracked output &&
+		# make sure "status" succeeded without writing index out
+		git diff-files | grep dir1/tracked
+	)
+	status=$?
+	chmod 775 .git
+	(exit $status)
+'
+
 test_done