[gtk/wip/otte/for-master] transform: Make sure the identity transform is equal to NULL

[Benjamin Otte <otte src gnome org>]

commit b50093d044324ac9ed0cc39368a35a0733c41483
Author: Benjamin Otte <otte redhat com>
Date:   Fri Feb 21 18:25:05 2020 +0100

    transform: Make sure the identity transform is equal to NULL

 gsk/gsktransform.c        |  7 +++++--
 testsuite/gsk/transform.c | 13 +++++++++++++
 2 files changed, 18 insertions(+), 2 deletions(-)
---
diff --git a/gsk/gsktransform.c b/gsk/gsktransform.c
index df6cb63bdd..19aa543b23 100644
--- a/gsk/gsktransform.c
+++ b/gsk/gsktransform.c
@@ -1683,8 +1683,11 @@ gsk_transform_equal (GskTransform *first,
   if (first == second)
     return TRUE;
 
-  if (first == NULL || second == NULL)
-    return FALSE;
+  if (first == NULL)
+    return gsk_transform_is_identity (second);
+
+  if (second == NULL)
+    return gsk_transform_is_identity (first);
 
   if (first->transform_class != second->transform_class)
     return FALSE;
diff --git a/testsuite/gsk/transform.c b/testsuite/gsk/transform.c
index 605d6f53cd..71ade76a49 100644
--- a/testsuite/gsk/transform.c
+++ b/testsuite/gsk/transform.c
@@ -332,6 +332,19 @@ test_identity (void)
   g_free (string);
 }
 
+static void
+test_identity_equal (void)
+{
+  GskTransform *id = gsk_transform_new ();
+
+  g_assert_true (gsk_transform_equal (NULL, NULL));
+  g_assert_true (gsk_transform_equal (id, NULL));
+  g_assert_true (gsk_transform_equal (NULL, id));
+  g_assert_true (gsk_transform_equal (id, id));
+
+  gsk_transform_unref (id);
+}
+
 static void
 test_print_parse (void)
 {