Add a test for custom dispatch_properties_changed

This tests that we call a custom dispatch_properties_changed,
even in the absence of connected notify handlers. (A recent
optimization broke that and caused a regression in GTK).

gobject/tests/custom-dispatch.c

@@ -0,0 +1,172 @@
+/* custom-dispatch.c: Test GObjectClass.dispatch_properties_changed
+ * Copyright (C) 2022 Red Hat, Inc.
+ *
+ * SPDX-License-Identifier: LGPL-2.1-or-later
+ *
+ * This work is provided "as is"; redistribution and modification
+ * in whole or in part, in any medium, physical or electronic is
+ * permitted without restriction.
+ *
+ * This work is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
+ *
+ * In no event shall the authors or contributors be liable for any
+ * direct, indirect, incidental, special, exemplary, or consequential
+ * damages (including, but not limited to, procurement of substitute
+ * goods or services; loss of use, data, or profits; or business
+ * interruption) however caused and on any theory of liability, whether
+ * in contract, strict liability, or tort (including negligence or
+ * otherwise) arising in any way out of the use of this software, even
+ * if advised of the possibility of such damage.
+ */
+
+#include <glib-object.h>
+
+typedef struct {
+  GObject parent_instance;
+  int foo;
+} TestObject;
+
+typedef struct {
+  GObjectClass parent_class;
+} TestObjectClass;
+
+typedef enum {
+  PROP_FOO = 1,
+  N_PROPERTIES,
+} TestObjectProperty;
+
+static GParamSpec *properties[N_PROPERTIES] = { NULL, };
+
+static GType test_object_get_type (void);
+G_DEFINE_TYPE (TestObject, test_object, G_TYPE_OBJECT)
+
+static void
+test_object_set_foo (TestObject *obj,
+                     gint        foo)
+{
+  if (obj->foo != foo)
+    {
+      obj->foo = foo;
+
+      g_assert (properties[PROP_FOO] != NULL);
+      g_object_notify_by_pspec (G_OBJECT (obj), properties[PROP_FOO]);
+    }
+}
+
+static void
+test_object_set_property (GObject *gobject,
+                          guint prop_id,
+                          const GValue *value,
+                          GParamSpec *pspec)
+{
+  TestObject *tobj = (TestObject *) gobject;
+
+  switch ((TestObjectProperty)prop_id)
+    {
+    case PROP_FOO:
+      test_object_set_foo (tobj, g_value_get_int (value));
+      break;
+
+    default:
+      g_assert_not_reached ();
+    }
+}
+
+static void
+test_object_get_property (GObject *gobject,
+                          guint prop_id,
+                          GValue *value,
+                          GParamSpec *pspec)
+{
+  TestObject *tobj = (TestObject *) gobject;
+
+  switch ((TestObjectProperty)prop_id)
+    {
+    case PROP_FOO:
+      g_value_set_int (value, tobj->foo);
+      break;
+
+    default:
+      g_assert_not_reached ();
+    }
+}
+
+static int dispatch_properties_called;
+
+static void
+test_object_dispatch_properties_changed (GObject     *object,
+                                         guint        n_pspecs,
+                                         GParamSpec **pspecs)
+{
+  dispatch_properties_called++;
+
+  G_OBJECT_CLASS (test_object_parent_class)->dispatch_properties_changed (object, n_pspecs, pspecs);
+}
+
+
+static void
+test_object_class_init (TestObjectClass *klass)
+{
+  GObjectClass *gobject_class = G_OBJECT_CLASS (klass);
+
+  properties[PROP_FOO] = g_param_spec_int ("foo", "Foo", "Foo",
+                                           -1, G_MAXINT,
+                                           0,
+                                           G_PARAM_READWRITE | G_PARAM_STATIC_STRINGS);
+
+  gobject_class->set_property = test_object_set_property;
+  gobject_class->get_property = test_object_get_property;
+  gobject_class->dispatch_properties_changed = test_object_dispatch_properties_changed;
+
+  g_object_class_install_properties (gobject_class, N_PROPERTIES, properties);
+}
+
+static void
+test_object_init (TestObject *self)
+{
+  self->foo = 42;
+}
+
+static gboolean
+object_has_notify_signal_handlers (gpointer instance)
+{
+  guint signal_id = g_signal_lookup ("notify", G_TYPE_OBJECT);
+
+  return g_signal_handler_find (instance, G_SIGNAL_MATCH_ID, signal_id, 0, NULL, NULL, NULL) != 0;
+}
+
+/* This instance init behavior is the thing we are testing:
+ *
+ * 1. Don't connect any notify handlers
+ * 2. Change the the foo property
+ * 3. Verify that our custom dispatch_properties_changed is called
+ */
+static void
+test_custom_dispatch (void)
+{
+  TestObject *obj;
+
+  g_test_summary ("Test that custom dispatch_properties_changed is called regardless of connected notify handlers");
+
+  obj = g_object_new (test_object_get_type (), NULL);
+
+  g_assert_false (object_has_notify_signal_handlers (obj));
+
+  g_assert_cmpint (dispatch_properties_called, ==, 0);
+  g_object_set (obj, "foo", 11, NULL);
+  g_assert_cmpint (dispatch_properties_called, ==, 1);
+
+  g_object_unref (obj);
+}
+
+int
+main (int argc, char *argv[])
+{
+  g_test_init (&argc, &argv, NULL);
+
+  g_test_add_func ("/properties/custom-dispatch", test_custom_dispatch);
+
+  return g_test_run ();
+}

gobject/tests/meson.build

@@ -31,6 +31,7 @@ marshalers_c = custom_target('marshalers_c',
 gobject_tests = {
   'notify-init' : {},
   'notify-init2' : {},
+  'custom-dispatch' : {},
   'qdata' : {},
   'accumulator' : {
     'source' : ['accumulator.c', marshalers_h, marshalers_c],