Remove empty directories when checking out a commit with fewer submodules

Change the unlink_entry function to use rmdir to remove submodule
directories.  Currently we try to use unlink, which will never succeed.

Of course rmdir will only succeed for empty (i.e. not checked out)
submodule directories.  Behaviour if a submodule is checked out stays
essentially the same: print a warning message and keep the submodule
directory.

Signed-off-by: Peter Collingbourne <peter@pcc.me.uk>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

2 files changed, 19 insertions, 2 deletions

diff --git a/t/t7400-submodule-basic.sh b/t/t7400-submodule-basic.sh
index a0cc99ab9f..1a4dc5f893 100755
--- a/t/t7400-submodule-basic.sh
+++ b/t/t7400-submodule-basic.sh
@@ -299,6 +299,15 @@ test_expect_success 'ls-files gracefully handles trailing slash' '
 
 '
 
+test_expect_success 'moving to a commit without submodule does not leave empty dir' '
+	rm -rf init &&
+	mkdir init &&
+	git reset --hard &&
+	git checkout initial &&
+	test ! -d init &&
+	git checkout second
+'
+
 test_expect_success 'submodule <invalid-path> warns' '
 
 	git submodule no-such-submodule 2> output.err &&
diff --git a/unpack-trees.c b/unpack-trees.c
index dd5999c356..b69847d6c9 100644
--- a/unpack-trees.c
+++ b/unpack-trees.c
@@ -61,8 +61,16 @@ static void unlink_entry(struct cache_entry *ce)
 {
 	if (has_symlink_or_noent_leading_path(ce->name, ce_namelen(ce)))
 		return;
-	if (unlink_or_warn(ce->name))
-		return;
+	if (S_ISGITLINK(ce->ce_mode)) {
+		if (rmdir(ce->name)) {
+			warning("unable to rmdir %s: %s",
+				ce->name, strerror(errno));
+			return;
+		}
+	}
+	else
+		if (unlink_or_warn(ce->name))
+			return;
 	schedule_dir_for_removal(ce->name, ce_namelen(ce));
 }