[PATCH 2/3] diff --submodule=diff: do not fail on ever-initialied deleted submodules

[David Turner <dturner@twosigma.com>]

If you have ever initialized a submodule, open_submodule will open it.
If you then delete the submodule's worktree directory (but don't
remove it from .gitmodules), git diff --submodule=diff would crash as
it attempted to chdir into the now-deleted working tree directory.

Signed-off-by: David Turner <dturner@twosigma.com>
---
 submodule.c                                  |  3 ++
 t/t4060-diff-submodule-option-diff-format.sh | 45 ++++++++++++++++++++++++----
 2 files changed, 43 insertions(+), 5 deletions(-)

diff --git a/submodule.c b/submodule.c
index 0b1d9c1dde..9031527a16 100644
--- a/submodule.c
+++ b/submodule.c
@@ -673,6 +673,9 @@ void show_submodule_inline_diff(struct diff_options *o, const char *path,
 	    !(right || is_null_oid(two)))
 		goto done;
 
+	if (!is_directory(path))
+		goto done;
+
 	if (left)
 		old_oid = one;
 	if (right)
diff --git a/t/t4060-diff-submodule-option-diff-format.sh b/t/t4060-diff-submodule-option-diff-format.sh
index 69b9946931..10e330c08a 100755
--- a/t/t4060-diff-submodule-option-diff-format.sh
+++ b/t/t4060-diff-submodule-option-diff-format.sh
@@ -703,10 +703,26 @@ test_expect_success 'path filter' '
 	diff_cmp expected actual
 '
 
-commit_file sm2
+cat >.gitmodules <<-EOF
+[submodule "sm2"]
+	path = sm2
+	url = bogus_url
+EOF
+git add .gitmodules
+commit_file sm2 .gitmodules
+
 test_expect_success 'given commit' '
 	git diff-index -p --submodule=diff HEAD^ >actual &&
 	cat >expected <<-EOF &&
+	diff --git a/.gitmodules b/.gitmodules
+	new file mode 100644
+	index 1234567..89abcde
+	--- /dev/null
+	+++ b/.gitmodules
+	@@ -0,0 +1,3 @@
+	+[submodule "sm2"]
+	+path = sm2
+	+url = bogus_url
 	Submodule sm1 $head7...0000000 (submodule deleted)
 	Submodule sm2 0000000...$head9 (new submodule)
 	diff --git a/sm2/foo8 b/sm2/foo8
@@ -728,15 +744,21 @@ test_expect_success 'given commit' '
 '
 
 test_expect_success 'setup .git file for sm2' '
-	(cd sm2 &&
-	 REAL="$(pwd)/../.real" &&
-	 mv .git "$REAL" &&
-	 echo "gitdir: $REAL" >.git)
+	git submodule absorbgitdirs sm2
 '
 
 test_expect_success 'diff --submodule=diff with .git file' '
 	git diff --submodule=diff HEAD^ >actual &&
 	cat >expected <<-EOF &&
+	diff --git a/.gitmodules b/.gitmodules
+	new file mode 100644
+	index 1234567..89abcde
+	--- /dev/null
+	+++ b/.gitmodules
+	@@ -0,0 +1,3 @@
+	+[submodule "sm2"]
+	+path = sm2
+	+url = bogus_url
 	Submodule sm1 $head7...0000000 (submodule deleted)
 	Submodule sm2 0000000...$head9 (new submodule)
 	diff --git a/sm2/foo8 b/sm2/foo8
@@ -757,6 +779,19 @@ test_expect_success 'diff --submodule=diff with .git file' '
 	diff_cmp expected actual
 '
 
+mv sm2 sm2-bak
+
+test_expect_success 'deleted submodule with .git file' '
+	git diff-index -p --submodule=diff HEAD >actual &&
+	cat >expected <<-EOF &&
+	Submodule sm1 $head7...0000000 (submodule deleted)
+	Submodule sm2 $head9...0000000 (submodule deleted)
+	EOF
+	diff_cmp expected actual
+'
+
+mv sm2-bak sm2
+
 test_expect_success 'setup nested submodule' '
 	git submodule add -f ./sm2 &&
 	git commit -a -m "add sm2" &&
-- 
2.11.GIT