slicelistmodel: Make constructor transfer full

This is for consistency with other wrapping list constructors.
We want them all to be transfer full, allow-none.

Update all callers.

gtk/gtklistlistmodel.c

@@ -36,7 +36,6 @@ struct _GtkListListModel
 {
   GObject parent_instance;
 
-  GType item_type;
   guint n_items;
   gpointer (* get_first) (gpointer);
   gpointer (* get_next) (gpointer, gpointer);
@@ -55,9 +54,7 @@ struct _GtkListListModelClass
 static GType
 gtk_list_list_model_get_item_type (GListModel *list)
 {
-  GtkListListModel *self = GTK_LIST_LIST_MODEL (list);
-
-  return self->item_type;
+  return G_TYPE_OBJECT;
 }
 
 static guint
@@ -143,8 +140,7 @@ gtk_list_list_model_init (GtkListListModel *self)
 }
 
 GtkListListModel *
-gtk_list_list_model_new (GType          item_type,
-                         gpointer       (* get_first) (gpointer),
+gtk_list_list_model_new (gpointer       (* get_first) (gpointer),
                          gpointer       (* get_next) (gpointer, gpointer),
                          gpointer       (* get_previous) (gpointer, gpointer),
                          gpointer       (* get_last) (gpointer),
@@ -161,8 +157,7 @@ gtk_list_list_model_new (GType          item_type,
        item = get_next (item, data))
     n_items++;
 
-  return gtk_list_list_model_new_with_size (item_type,
-                                            n_items,
+  return gtk_list_list_model_new_with_size (n_items,
                                             get_first,
                                             get_next,
                                             get_previous,
@@ -173,8 +168,7 @@ gtk_list_list_model_new (GType          item_type,
 }
 
 GtkListListModel *
-gtk_list_list_model_new_with_size (GType          item_type,
-                                   guint          n_items,
+gtk_list_list_model_new_with_size (guint          n_items,
                                    gpointer       (* get_first) (gpointer),
                                    gpointer       (* get_next) (gpointer, gpointer),
                                    gpointer       (* get_previous) (gpointer, gpointer),
@@ -185,7 +179,6 @@ gtk_list_list_model_new_with_size (GType          item_type,
 {
   GtkListListModel *result;
 
-  g_return_val_if_fail (g_type_is_a (item_type, G_TYPE_OBJECT), NULL);
   g_return_val_if_fail (get_first != NULL, NULL);
   g_return_val_if_fail (get_next != NULL, NULL);
   g_return_val_if_fail (get_previous != NULL, NULL);
@@ -193,7 +186,6 @@ gtk_list_list_model_new_with_size (GType          item_type,
 
   result = g_object_new (GTK_TYPE_LIST_LIST_MODEL, NULL);
 
-  result->item_type = item_type;
   result->n_items = n_items;
   result->get_first = get_first;
   result->get_next = get_next;

gtk/gtklistlistmodelprivate.h

@@ -37,8 +37,7 @@ typedef struct _GtkListListModelClass GtkListListModelClass;
 
 GType                   gtk_list_list_model_get_type            (void) G_GNUC_CONST;
 
-GtkListListModel *      gtk_list_list_model_new                 (GType                   item_type,
-                                                                 gpointer                (* get_first) (gpointer),
+GtkListListModel *      gtk_list_list_model_new                 (gpointer                (* get_first) (gpointer),
                                                                  gpointer                (* get_next) (gpointer, gpointer),
                                                                  gpointer                (* get_previous) (gpointer, gpointer),
                                                                  gpointer                (* get_last) (gpointer),
@@ -46,8 +45,7 @@ GtkListListModel *      gtk_list_list_model_new                 (GType
                                                                  gpointer                data,
                                                                  GDestroyNotify          notify);
 
-GtkListListModel *      gtk_list_list_model_new_with_size       (GType                   item_type,
-                                                                 guint                   n_items,
+GtkListListModel *      gtk_list_list_model_new_with_size       (guint                   n_items,
                                                                  gpointer                (* get_first) (gpointer),
                                                                  gpointer                (* get_next) (gpointer, gpointer),
                                                                  gpointer                (* get_previous) (gpointer, gpointer),

gtk/gtkslicelistmodel.c

@@ -30,11 +30,12 @@
  * @short_description: A list model that presents a slice out of a larger list
  * @see_also: #GListModel
  *
- * #GtkSliceListModel is a list model that takes a list model and presents a slice of
- * that model.
+ * #GtkSliceListModel is a list model that takes a list model and presents a
+ * slice of that model.
  *
- * This is useful when implementing paging by setting the size to the number of elements
- * per page and updating the offset whenever a different page is opened.
+ * This is useful when implementing paging by setting the size to the number
+ * of elements per page and updating the offset whenever a different page is
+ * opened.
  */
 
 #define DEFAULT_SIZE 10
@@ -300,7 +301,7 @@ gtk_slice_list_model_init (GtkSliceListModel *self)
 
 /**
  * gtk_slice_list_model_new:
- * @model: (transfer none) (allow-none): The model to use
+ * @model: (transfer full) (allow-none): The model to use, or %NULL
  * @offset: the offset of the slice
  * @size: maximum size of the slice
  *
@@ -314,13 +315,20 @@ gtk_slice_list_model_new (GListModel *model,
                           guint       offset,
                           guint       size)
 {
+  GtkSliceListModel *self;
+
   g_return_val_if_fail (model == NULL || G_IS_LIST_MODEL (model), NULL);
 
-  return g_object_new (GTK_TYPE_SLICE_LIST_MODEL,
+  self = g_object_new (GTK_TYPE_SLICE_LIST_MODEL,
                        "model", model,
                        "offset", offset,
                        "size", size,
                        NULL);
+
+  /* consume the reference */
+  g_clear_object (&model);
+
+  return self;
 }
 
 /**

gtk/gtkwidget.c

@@ -11535,8 +11535,7 @@ gtk_widget_observe_children (GtkWidget *widget)
   if (priv->children_observer)
     return g_object_ref (G_LIST_MODEL (priv->children_observer));
 
-  priv->children_observer = gtk_list_list_model_new (GTK_TYPE_WIDGET,
-                                                     (gpointer) gtk_widget_get_first_child,
+  priv->children_observer = gtk_list_list_model_new ((gpointer) gtk_widget_get_first_child,
                                                      (gpointer) gtk_widget_get_next_sibling,
                                                      (gpointer) gtk_widget_get_prev_sibling,
                                                      (gpointer) gtk_widget_get_last_child,
@@ -11622,14 +11621,13 @@ gtk_widget_observe_controllers (GtkWidget *widget)
   if (priv->controller_observer)
     return g_object_ref (G_LIST_MODEL (priv->controller_observer));
 
-  priv->controller_observer = gtk_list_list_model_new (GTK_TYPE_EVENT_CONTROLLER,
-                                                      gtk_widget_controller_list_get_first,
-                                                      gtk_widget_controller_list_get_next,
-                                                      gtk_widget_controller_list_get_prev,
-                                                      NULL,
-                                                      (gpointer) g_object_ref,
-                                                      widget,
-                                                      gtk_widget_controller_observer_destroyed);
+  priv->controller_observer = gtk_list_list_model_new (gtk_widget_controller_list_get_first,
+                                                       gtk_widget_controller_list_get_next,
+                                                       gtk_widget_controller_list_get_prev,
+                                                       NULL,
+                                                       (gpointer) g_object_ref,
+                                                       widget,
+                                                       gtk_widget_controller_observer_destroyed);
 
   return G_LIST_MODEL (priv->controller_observer);
 }