[PATCH v4 1/2] describe: setup working tree for --dirty

[Sebastian Staudt <koraktor@gmail.com>]

We don't use NEED_WORK_TREE when running the git-describe builtin,
since you should be able to describe a commit even in a bare repository.
However, the --dirty flag does need a working tree. Since we don't call
setup_work_tree(), it uses whatever directory we happen to be in. That's
unlikely to match our index, meaning we'd say "dirty" even when the real
working tree is clean.

We can fix that by calling setup_work_tree() once we know that the user
has asked for --dirty.

The --broken option also needs a working tree. But because its
implementation calls git-diff-index we don‘t have to setup the working
tree in the git-describe process.

Signed-off-by: Sebastian Staudt <koraktor@gmail.com>
Helped-by: Jeff King <peff@peff.net>
---
 builtin/describe.c  |  1 +
 t/t6120-describe.sh | 33 +++++++++++++++++++++++++++++++++
 2 files changed, 34 insertions(+)

diff --git a/builtin/describe.c b/builtin/describe.c
index cc118448ee..b5b7abdc8f 100644
--- a/builtin/describe.c
+++ b/builtin/describe.c
@@ -629,6 +629,7 @@ int cmd_describe(int argc, const char **argv, const char *prefix)
 			struct argv_array args = ARGV_ARRAY_INIT;
 			int fd, result;
 
+			setup_work_tree();
 			read_cache();
 			refresh_index(&the_index, REFRESH_QUIET|REFRESH_UNMERGED,
 				      NULL, NULL, NULL);
diff --git a/t/t6120-describe.sh b/t/t6120-describe.sh
index d639d94696..7cfed77c52 100755
--- a/t/t6120-describe.sh
+++ b/t/t6120-describe.sh
@@ -145,14 +145,38 @@ check_describe A-* HEAD
 
 check_describe "A-*[0-9a-f]" --dirty
 
+test_expect_success 'describe --dirty with --work-tree' '
+	(
+		cd "$TEST_DIRECTORY" &&
+		git --git-dir "$TRASH_DIRECTORY/.git" --work-tree "$TRASH_DIRECTORY" describe --dirty >"$TRASH_DIRECTORY/out"
+	) &&
+	grep "^A-[1-9][0-9]\?-g[0-9a-f]\+$" out
+'
+
 test_expect_success 'set-up dirty work tree' '
 	echo >>file
 '
 
 check_describe "A-*[0-9a-f]-dirty" --dirty
 
+test_expect_success 'describe --dirty with --work-tree' '
+	(
+		cd "$TEST_DIRECTORY" &&
+		git --git-dir "$TRASH_DIRECTORY/.git" --work-tree "$TRASH_DIRECTORY" describe --dirty >"$TRASH_DIRECTORY/out"
+	) &&
+	grep "^A-[1-9][0-9]\?-g[0-9a-f]\+-dirty$" out
+'
+
 check_describe "A-*[0-9a-f].mod" --dirty=.mod
 
+test_expect_success 'describe --dirty=.mod with --work-tree' '
+	(
+		cd "$TEST_DIRECTORY" &&
+		git --git-dir "$TRASH_DIRECTORY/.git" --work-tree "$TRASH_DIRECTORY" describe --dirty=.mod >"$TRASH_DIRECTORY/out"
+	) &&
+	grep "^A-[1-9][0-9]\?-g[0-9a-f]\+.mod$" out
+'
+
 test_expect_success 'describe --dirty HEAD' '
 	test_must_fail git describe --dirty HEAD
 '
@@ -303,8 +327,17 @@ test_expect_success 'describe chokes on severely broken submodules' '
 	mv .git/modules/sub1/ .git/modules/sub_moved &&
 	test_must_fail git describe --dirty
 '
+
 test_expect_success 'describe ignoring a broken submodule' '
 	git describe --broken >out &&
+	grep broken out
+'
+
+test_expect_success 'describe with --work-tree ignoring a broken submodule' '
+	(
+		cd "$TEST_DIRECTORY" &&
+		git --git-dir "$TRASH_DIRECTORY/.git" --work-tree "$TRASH_DIRECTORY" describe --broken >"$TRASH_DIRECTORY/out"
+	) &&
 	test_when_finished "mv .git/modules/sub_moved .git/modules/sub1" &&
 	grep broken out
 '
-- 
2.20.1