thodg/libgit2

diff --git a/include/git2/diff.h b/include/git2/diff.h
index d9ceadf..cc16d01 100644
--- a/include/git2/diff.h
+++ b/include/git2/diff.h
@@ -124,6 +124,13 @@ typedef enum {
 	 *  adds all files under the directory as IGNORED entries, too.
 	 */
 	GIT_DIFF_RECURSE_IGNORED_DIRS = (1 << 18),
+	/** For an untracked directory, diff can immediately label it UNTRACKED,
+	 *  but this differs from core Git which scans underneath for untracked
+	 *  or ignored files and marks the directory ignored unless it contains
+	 *  untracked files under it.  That search can be slow.  This flag makes
+	 *  diff skip ahead and immediately report the directory as untracked.
+	 */
+	GIT_DIFF_FAST_UNTRACKED_DIRS = (1 << 19),
 } git_diff_option_t;
 
 /**
diff --git a/include/git2/submodule.h b/include/git2/submodule.h
index 40934b3..0046650 100644
--- a/include/git2/submodule.h
+++ b/include/git2/submodule.h
@@ -103,20 +103,20 @@ typedef enum {
  * * WD_UNTRACKED      - wd contains untracked files
  */
 typedef enum {
-	 GIT_SUBMODULE_STATUS_IN_HEAD           = (1u << 0),
-	 GIT_SUBMODULE_STATUS_IN_INDEX          = (1u << 1),
-	 GIT_SUBMODULE_STATUS_IN_CONFIG         = (1u << 2),
-	 GIT_SUBMODULE_STATUS_IN_WD             = (1u << 3),
-	 GIT_SUBMODULE_STATUS_INDEX_ADDED       = (1u << 4),
-	 GIT_SUBMODULE_STATUS_INDEX_DELETED     = (1u << 5),
-	 GIT_SUBMODULE_STATUS_INDEX_MODIFIED    = (1u << 6),
-	 GIT_SUBMODULE_STATUS_WD_UNINITIALIZED  = (1u << 7),
-	 GIT_SUBMODULE_STATUS_WD_ADDED          = (1u << 8),
-	 GIT_SUBMODULE_STATUS_WD_DELETED        = (1u << 9),
-	 GIT_SUBMODULE_STATUS_WD_MODIFIED       = (1u << 10),
-	 GIT_SUBMODULE_STATUS_WD_INDEX_MODIFIED = (1u << 11),
-	 GIT_SUBMODULE_STATUS_WD_WD_MODIFIED    = (1u << 12),
-	 GIT_SUBMODULE_STATUS_WD_UNTRACKED      = (1u << 13),
+	GIT_SUBMODULE_STATUS_IN_HEAD           = (1u << 0),
+	GIT_SUBMODULE_STATUS_IN_INDEX          = (1u << 1),
+	GIT_SUBMODULE_STATUS_IN_CONFIG         = (1u << 2),
+	GIT_SUBMODULE_STATUS_IN_WD             = (1u << 3),
+	GIT_SUBMODULE_STATUS_INDEX_ADDED       = (1u << 4),
+	GIT_SUBMODULE_STATUS_INDEX_DELETED     = (1u << 5),
+	GIT_SUBMODULE_STATUS_INDEX_MODIFIED    = (1u << 6),
+	GIT_SUBMODULE_STATUS_WD_UNINITIALIZED  = (1u << 7),
+	GIT_SUBMODULE_STATUS_WD_ADDED          = (1u << 8),
+	GIT_SUBMODULE_STATUS_WD_DELETED        = (1u << 9),
+	GIT_SUBMODULE_STATUS_WD_MODIFIED       = (1u << 10),
+	GIT_SUBMODULE_STATUS_WD_INDEX_MODIFIED = (1u << 11),
+	GIT_SUBMODULE_STATUS_WD_WD_MODIFIED    = (1u << 12),
+	GIT_SUBMODULE_STATUS_WD_UNTRACKED      = (1u << 13),
 } git_submodule_status_t;
 
 #define GIT_SUBMODULE_STATUS__IN_FLAGS \
diff --git a/src/diff.c b/src/diff.c
index 58c7eac..cea3fdb 100644
--- a/src/diff.c
+++ b/src/diff.c
@@ -698,56 +698,58 @@ static bool entry_is_prefixed(
 			item->path[pathlen] == '/');
 }
 
-static int handle_unmatched_new_directory(
-	git_diff_list *diff, diff_in_progress *info, git_delta_t *delta)
+static int diff_scan_inside_untracked_dir(
+	git_diff_list *diff, diff_in_progress *info, git_delta_t *delta_type)
 {
 	int error = 0;
-	const git_index_entry *nitem = info->nitem;
-	bool contains_oitem = entry_is_prefixed(diff, info->oitem, nitem);
-	bool recurse_into_dir =
-		(*delta == GIT_DELTA_UNTRACKED &&
-		 DIFF_FLAG_IS_SET(diff, GIT_DIFF_RECURSE_UNTRACKED_DIRS)) ||
-		(*delta == GIT_DELTA_IGNORED &&
-		 DIFF_FLAG_IS_SET(diff, GIT_DIFF_RECURSE_IGNORED_DIRS));
-
-	/* do not advance into directories that contain a .git file */
-	if (!contains_oitem && recurse_into_dir) {
-		git_buf *full = NULL;
-		if (git_iterator_current_workdir_path(&full, info->new_iter) < 0)
-			return -1;
-		if (git_path_contains_dir(full, DOT_GIT))
-			recurse_into_dir = false;
-	}
+	git_buf base = GIT_BUF_INIT;
+	bool is_ignored;
 
-	/* if directory is ignored, remember ignore_prefix */
-	if ((contains_oitem || recurse_into_dir) &&
-		*delta == GIT_DELTA_UNTRACKED &&
-		git_iterator_current_is_ignored(info->new_iter))
-	{
-		git_buf_sets(&info->ignore_prefix, info->nitem->path);
-		*delta = GIT_DELTA_IGNORED;
-
-		/* skip recursion if we've just learned this is ignored */
-		if (DIFF_FLAG_ISNT_SET(diff, GIT_DIFF_RECURSE_IGNORED_DIRS))
-			recurse_into_dir = false;
-	}
+	*delta_type = GIT_DELTA_IGNORED;
+	git_buf_sets(&base, info->nitem->path);
 
-	if (contains_oitem || recurse_into_dir) {
-		/* advance into directory */
-		error = git_iterator_advance_into(&info->nitem, info->new_iter);
+	/* advance into untracked directory */
+	if ((error = git_iterator_advance_into(&info->nitem, info->new_iter)) < 0) {
 
-		/* if directory is empty, can't advance into it, so skip */
+		/* skip ahead if empty */
 		if (error == GIT_ENOTFOUND) {
 			giterr_clear();
 			error = git_iterator_advance(&info->nitem, info->new_iter);
+		}
 
-			git_buf_clear(&info->ignore_prefix);
+		return error;
+	}
+
+	/* look for actual untracked file */
+	while (!diff->pfxcomp(info->nitem->path, git_buf_cstr(&base))) {
+		is_ignored = git_iterator_current_is_ignored(info->new_iter);
+
+		/* need to recurse into non-ignored directories */
+		if (!is_ignored && S_ISDIR(info->nitem->mode)) {
+			if ((error = git_iterator_advance_into(
+					 &info->nitem, info->new_iter)) < 0)
+				break;
+			continue;
+		}
+
+		/* found a non-ignored item - treat parent dir as untracked */
+		if (!is_ignored) {
+			*delta_type = GIT_DELTA_UNTRACKED;
+			break;
 		}
 
-		/* return UNMODIFIED to tell caller not to create a new record */
-		*delta = GIT_DELTA_UNMODIFIED;
+		if ((error = git_iterator_advance(&info->nitem, info->new_iter)) < 0)
+			break;
+	}
+
+	/* finish off scan */
+	while (!diff->pfxcomp(info->nitem->path, git_buf_cstr(&base))) {
+		if ((error = git_iterator_advance(&info->nitem, info->new_iter)) < 0)
+			break;
 	}
 
+	git_buf_free(&base);
+
 	return error;
 }
 
@@ -757,36 +759,116 @@ static int handle_unmatched_new_item(
 	int error = 0;
 	const git_index_entry *nitem = info->nitem;
 	git_delta_t delta_type = GIT_DELTA_UNTRACKED;
+	bool contains_oitem;
 
-	/* check if contained in ignored parent directory */
-	if (git_buf_len(&info->ignore_prefix) &&
-		diff->pfxcomp(nitem->path, git_buf_cstr(&info->ignore_prefix)) == 0)
-		delta_type = GIT_DELTA_IGNORED;
+	/* check if this is a prefix of the other side */
+	contains_oitem = entry_is_prefixed(diff, info->oitem, nitem);
+
+	/* check if this is contained in an ignored parent directory */
+	if (git_buf_len(&info->ignore_prefix)) {
+		if (diff->pfxcomp(nitem->path, git_buf_cstr(&info->ignore_prefix)) == 0)
+			delta_type = GIT_DELTA_IGNORED;
+		else
+			git_buf_clear(&info->ignore_prefix);
+	}
 
 	if (S_ISDIR(nitem->mode)) {
-		error = handle_unmatched_new_directory(diff, info, &delta_type);
+		bool recurse_into_dir = contains_oitem;
+
+		/* if not already inside an ignored dir, check if this is ignored */
+		if (delta_type != GIT_DELTA_IGNORED &&
+			git_iterator_current_is_ignored(info->new_iter))
+		{
+			delta_type = GIT_DELTA_IGNORED;
+			git_buf_sets(&info->ignore_prefix, nitem->path);
+		}
+
+		/* check if user requests recursion into this type of dir */
+		recurse_into_dir = contains_oitem ||
+			(delta_type == GIT_DELTA_UNTRACKED &&
+			 DIFF_FLAG_IS_SET(diff, GIT_DIFF_RECURSE_UNTRACKED_DIRS)) ||
+			(delta_type == GIT_DELTA_IGNORED &&
+			 DIFF_FLAG_IS_SET(diff, GIT_DIFF_RECURSE_IGNORED_DIRS));
+
+		/* do not advance into directories that contain a .git file */
+		if (recurse_into_dir) {
+			git_buf *full = NULL;
+			if (git_iterator_current_workdir_path(&full, info->new_iter) < 0)
+				return -1;
+			if (full && git_path_contains_dir(full, DOT_GIT))
+				recurse_into_dir = false;
+		}
 
-		if (error || delta_type == GIT_DELTA_UNMODIFIED)
-			return error;
+		/* still have to look into untracked directories to match core git -
+		 * with no untracked files, directory is treated as ignored
+		 */
+		if (!recurse_into_dir &&
+			delta_type == GIT_DELTA_UNTRACKED &&
+			DIFF_FLAG_ISNT_SET(diff, GIT_DIFF_FAST_UNTRACKED_DIRS))
+		{
+			git_diff_delta *last;
+
+			/* attempt to insert record for this directory */
+			if ((error = diff_delta__from_one(diff, delta_type, nitem)) < 0)
+				return error;
+
+			/* if delta wasn't created (because of rules), just skip ahead */
+			last = diff_delta__last_for_item(diff, nitem);
+			if (!last)
+				return git_iterator_advance(&info->nitem, info->new_iter);
+
+			/* iterate into dir looking for an actual untracked file */
+			if (diff_scan_inside_untracked_dir(diff, info, &delta_type) < 0)
+				return -1;
+
+			/* it iteration changed delta type, the update the record */
+			if (delta_type == GIT_DELTA_IGNORED) {
+				last->status = GIT_DELTA_IGNORED;
+
+				/* remove the record if we don't want ignored records */
+				if (DIFF_FLAG_ISNT_SET(diff, GIT_DIFF_INCLUDE_IGNORED)) {
+					git_vector_pop(&diff->deltas);
+					git__free(last);
+				}
+			}
+
+			return 0;
+		}
+
+		/* try to advance into directory if necessary */
+		if (recurse_into_dir) {
+			error = git_iterator_advance_into(&info->nitem, info->new_iter);
+
+			/* if real error or no error, proceed with iteration */
+			if (error != GIT_ENOTFOUND)
+				return error;
+			giterr_clear();
+
+			/* if directory is empty, can't advance into it, so either skip
+			 * it or ignore it
+			 */
+			if (contains_oitem)
+				return git_iterator_advance(&info->nitem, info->new_iter);
+			delta_type = GIT_DELTA_IGNORED;
+		}
 	}
 
-	/* In core git, the next two "else if" clauses are effectively
-	 * reversed -- i.e. when an untracked file contained in an
-	 * ignored directory is individually ignored, it shows up as an
-	 * ignored file in the diff list, even though other untracked
-	 * files in the same directory are skipped completely.
+	/* In core git, the next two checks are effectively reversed --
+	 * i.e. when an file contained in an ignored directory is explicitly
+	 * ignored, it shows up as an ignored file in the diff list, even though
+	 * other untracked files in the same directory are skipped completely.
 	 *
-	 * To me, this is odd.  If the directory is ignored and the file
-	 * is untracked, we should skip it consistently, regardless of
-	 * whether it happens to match a pattern in the ignore file.
+	 * To me, this seems odd.  If the directory is ignored and the file is
+	 * untracked, we should skip it consistently, regardless of whether it
+	 * happens to match a pattern in the ignore file.
 	 *
-	 * To match the core git behavior, just reverse the following
-	 * two "else if" cases so that individual file ignores are
-	 * checked before container directory exclusions are used to
-	 * skip the file.
+	 * To match the core git behavior, reverse the following two if checks
+	 * so that individual file ignores are checked before container
+	 * directory exclusions are used to skip the file.
 	 */
 	else if (delta_type == GIT_DELTA_IGNORED &&
-			 DIFF_FLAG_ISNT_SET(diff, GIT_DIFF_RECURSE_IGNORED_DIRS))
+		DIFF_FLAG_ISNT_SET(diff, GIT_DIFF_RECURSE_IGNORED_DIRS))
+		/* item contained in ignored directory, so skip over it */
 		return git_iterator_advance(&info->nitem, info->new_iter);
 
 	else if (git_iterator_current_is_ignored(info->new_iter))
@@ -795,15 +877,16 @@ static int handle_unmatched_new_item(
 	else if (info->new_iter->type != GIT_ITERATOR_TYPE_WORKDIR)
 		delta_type = GIT_DELTA_ADDED;
 
+	/* Actually create the record for this item if necessary */
 	if ((error = diff_delta__from_one(diff, delta_type, nitem)) < 0)
 		return error;
 
-	/* if we are generating TYPECHANGE records then check for that
-	 * instead of just generating an ADDED/UNTRACKED record
+	/* If user requested TYPECHANGE records, then check for that instead of
+	 * just generating an ADDED/UNTRACKED record
 	 */
 	if (delta_type != GIT_DELTA_IGNORED &&
 		DIFF_FLAG_IS_SET(diff, GIT_DIFF_INCLUDE_TYPECHANGE_TREES) &&
-		entry_is_prefixed(diff, info->oitem, nitem))
+		contains_oitem)
 	{
 		/* this entry was prefixed with a tree - make TYPECHANGE */
 		git_diff_delta *last = diff_delta__last_for_item(diff, nitem);
diff --git a/src/vector.c b/src/vector.c
index f4a818e..5ba2fab 100644
--- a/src/vector.c
+++ b/src/vector.c
@@ -277,15 +277,13 @@ void git_vector_swap(git_vector *a, git_vector *b)
 
 int git_vector_resize_to(git_vector *v, size_t new_length)
 {
-	if (new_length <= v->length)
-		return 0;
-
 	if (new_length > v->_alloc_size &&
 		resize_vector(v, new_length) < 0)
 		return -1;
 
-	memset(&v->contents[v->length], 0,
-		sizeof(void *) * (new_length - v->length));
+	if (new_length > v->length)
+		memset(&v->contents[v->length], 0,
+			sizeof(void *) * (new_length - v->length));
 
 	v->length = new_length;
 
diff --git a/tests-clar/status/status_helpers.c b/tests-clar/status/status_helpers.c
index 24546d4..f073c24 100644
--- a/tests-clar/status/status_helpers.c
+++ b/tests-clar/status/status_helpers.c
@@ -40,7 +40,8 @@ int cb_status__single(const char *p, unsigned int s, void *payload)
 {
 	status_entry_single *data = (status_entry_single *)payload;
 
-	GIT_UNUSED(p);
+	if (data->debug)
+		fprintf(stderr, "%02d: %s (%04x)\n", data->count, p, s);
 
 	data->count++;
 	data->status = s;
diff --git a/tests-clar/status/status_helpers.h b/tests-clar/status/status_helpers.h
index 1aa0263..ae1469e 100644
--- a/tests-clar/status/status_helpers.h
+++ b/tests-clar/status/status_helpers.h
@@ -24,6 +24,7 @@ extern int cb_status__count(const char *p, unsigned int s, void *payload);
 typedef struct {
 	int count;
 	unsigned int status;
+	bool debug;
 } status_entry_single;
 
 /* cb_status__single takes payload of "status_entry_single *" */
diff --git a/tests-clar/status/worktree.c b/tests-clar/status/worktree.c
index a9b8a12..0138b17 100644
--- a/tests-clar/status/worktree.c
+++ b/tests-clar/status/worktree.c
@@ -258,9 +258,8 @@ void test_status_worktree__ignores(void)
 
 static int cb_status__check_592(const char *p, unsigned int s, void *payload)
 {
-	GIT_UNUSED(payload);
-
-	if (s != GIT_STATUS_WT_DELETED || (payload != NULL && strcmp(p, (const char *)payload) != 0))
+	if (s != GIT_STATUS_WT_DELETED ||
+		(payload != NULL && strcmp(p, (const char *)payload) != 0))
 		return -1;
 
 	return 0;
diff --git a/tests-clar/submodule/status.c b/tests-clar/submodule/status.c
index 282e827..fca84af 100644
--- a/tests-clar/submodule/status.c
+++ b/tests-clar/submodule/status.c
@@ -383,3 +383,30 @@ void test_submodule_status__iterator(void)
 
 	cl_git_pass(git_status_foreach_ext(g_repo, &opts, confirm_submodule_status, &exp));
 }
+
+void test_submodule_status__untracked_dirs_containing_ignored_files(void)
+{
+	git_buf path = GIT_BUF_INIT;
+	unsigned int status, expected;
+	git_submodule *sm;
+
+	cl_git_pass(git_buf_joinpath(&path, git_repository_path(g_repo), "modules/sm_unchanged/info/exclude"));
+	cl_git_append2file(git_buf_cstr(&path), "\n*.ignored\n");
+
+	cl_git_pass(git_buf_joinpath(&path, git_repository_workdir(g_repo), "sm_unchanged/directory"));
+	cl_git_pass(git_futils_mkdir(git_buf_cstr(&path), NULL, 0755, 0));
+	cl_git_pass(git_buf_joinpath(&path, git_buf_cstr(&path), "i_am.ignored"));
+	cl_git_mkfile(git_buf_cstr(&path), "ignored this file, please\n");
+
+	cl_git_pass(git_submodule_lookup(&sm, g_repo, "sm_unchanged"));
+	cl_git_pass(git_submodule_status(&status, sm));
+
+	cl_assert(GIT_SUBMODULE_STATUS_IS_UNMODIFIED(status));
+
+	expected = GIT_SUBMODULE_STATUS_IN_HEAD |
+		GIT_SUBMODULE_STATUS_IN_INDEX |
+		GIT_SUBMODULE_STATUS_IN_CONFIG |
+		GIT_SUBMODULE_STATUS_IN_WD;
+
+	cl_assert(status == expected);
+}