Fix bugs in new diff patch code

This fixes all the bugs in the new diff patch code.  The only
really interesting one is that when we merge two diffs, we now
have to actually exclude diff delta records that are not supposed
to be tracked, as opposed to before where they could be included
because they would be skipped silently by `git_diff_foreach()`.
Other than that, there are just minor errors.

1 files changed, 30 insertions, 0 deletions

diff --git a/src/diff.c b/src/diff.c
index 7c8e2a9bb..7ee919b5a 100644
--- a/src/diff.c
+++ b/src/diff.c
@@ -807,6 +807,28 @@ on_error:
 	return -1;
 }
 
+
+bool git_diff_delta__should_skip(
+	git_diff_options *opts, git_diff_delta *delta)
+{
+	uint32_t flags = opts ? opts->flags : 0;
+
+	if (delta->status == GIT_DELTA_UNMODIFIED &&
+		(flags & GIT_DIFF_INCLUDE_UNMODIFIED) == 0)
+		return true;
+
+	if (delta->status == GIT_DELTA_IGNORED &&
+		(flags & GIT_DIFF_INCLUDE_IGNORED) == 0)
+		return true;
+
+	if (delta->status == GIT_DELTA_UNTRACKED &&
+		(flags & GIT_DIFF_INCLUDE_UNTRACKED) == 0)
+		return true;
+
+	return false;
+}
+
+
 int git_diff_merge(
 	git_diff_list *onto,
 	const git_diff_list *from)
@@ -843,6 +865,14 @@ int git_diff_merge(
 			j++;
 		}
 
+		/* the ignore rules for the target may not match the source
+		 * or the result of a merged delta could be skippable...
+		 */
+		if (git_diff_delta__should_skip(&onto->opts, delta)) {
+			git__free(delta);
+			continue;
+		}
+
 		if ((error = !delta ? -1 : git_vector_insert(&onto_new, delta)) < 0)
 			break;
 	}