gsignal: Add G_CONNECT_DEFAULT

This makes calls to g_signal_connect_data() and g_signal_connect_object()
with default flags more self-documenting.

Signed-off-by: Simon McVittie <smcv@collabora.com>

gio/gcancellable.c

@@ -589,7 +589,7 @@ g_cancellable_connect (GCancellable   *cancellable,
       id = g_signal_connect_data (cancellable, "cancelled",
                                   callback, data,
                                   (GClosureNotify) data_destroy_func,
-                                  0);
+                                  G_CONNECT_DEFAULT);
 
       g_mutex_unlock (&cancellable_mutex);
     }

gio/gdbusobjectmanagerclient.c

@@ -1456,7 +1456,7 @@ initable_init (GInitable     *initable,
                             G_CALLBACK (on_notify_g_name_owner),
                             weak_ref_new (G_OBJECT (manager)),
                             (GClosureNotify) weak_ref_free,
-                            0  /* flags */);
+                            G_CONNECT_DEFAULT);
 
   manager->priv->signal_signal_id =
       g_signal_connect_data (manager->priv->control_proxy,
@@ -1464,7 +1464,7 @@ initable_init (GInitable     *initable,
                             G_CALLBACK (on_control_proxy_g_signal),
                             weak_ref_new (G_OBJECT (manager)),
                             (GClosureNotify) weak_ref_free,
-                            0  /* flags */);
+                            G_CONNECT_DEFAULT);
 
   manager->priv->name_owner = g_dbus_proxy_get_name_owner (manager->priv->control_proxy);
   if (manager->priv->name_owner == NULL && manager->priv->name != NULL)

gio/gdbusserver.c

@@ -630,7 +630,7 @@ g_dbus_server_start (GDBusServer *server)
                                                          G_CALLBACK (on_run),
                                                          g_object_ref (server),
                                                          (GClosureNotify) g_object_unref,
-                                                         0  /* flags */);
+                                                         G_CONNECT_DEFAULT);
   g_socket_service_start (G_SOCKET_SERVICE (server->listener));
   server->active = TRUE;
   g_object_notify (G_OBJECT (server), "active");

gio/glocalfilemonitor.c

@@ -809,7 +809,8 @@ g_local_file_monitor_start (GLocalFileMonitor *local_monitor,
 
       local_monitor->mount_monitor = g_unix_mount_monitor_get ();
       g_signal_connect_object (local_monitor->mount_monitor, "mounts-changed",
-                               G_CALLBACK (g_local_file_monitor_mounts_changed), local_monitor, 0);
+                               G_CALLBACK (g_local_file_monitor_mounts_changed), local_monitor,
+                               G_CONNECT_DEFAULT);
 #endif
     }
 
@@ -924,7 +925,7 @@ g_local_file_monitor_new_in_worker (const gchar           *pathname,
     {
       if (callback)
         g_signal_connect_data (monitor, "changed", G_CALLBACK (callback),
-                               user_data, destroy_user_data, 0  /* flags */);
+                               user_data, destroy_user_data, G_CONNECT_DEFAULT);
 
       g_local_file_monitor_start (monitor, pathname, is_directory, flags, GLIB_PRIVATE_CALL(g_get_worker_context) ());
     }

gio/gsubprocess.c

@@ -756,7 +756,9 @@ g_subprocess_wait_async (GSubprocess         *subprocess,
        * see the cancellation in the _finish().
        */
       if (cancellable)
-        g_signal_connect_object (cancellable, "cancelled", G_CALLBACK (g_subprocess_wait_cancelled), task, 0);
+        g_signal_connect_object (cancellable, "cancelled",
+                                 G_CALLBACK (g_subprocess_wait_cancelled),
+                                 task, G_CONNECT_DEFAULT);
 
       subprocess->pending_waits = g_slist_prepend (subprocess->pending_waits, task);
       task = NULL;

gio/gtask.c

@@ -1530,7 +1530,8 @@ g_task_start_task_thread (GTask           *task,
       g_signal_connect_data (task->cancellable, "cancelled",
                              G_CALLBACK (task_thread_cancelled),
                              g_object_ref (task),
-                             task_thread_cancelled_disconnect_notify, 0);
+                             task_thread_cancelled_disconnect_notify,
+                             G_CONNECT_DEFAULT);
     }
 
   if (g_private_get (&task_private))

gobject/gobject.c

@@ -3093,8 +3093,8 @@ g_object_get_property (GObject	   *object,
  *
  * The signal specs expected by this function have the form
  * "modifier::signal_name", where modifier can be one of the following:
- * - signal: equivalent to g_signal_connect_data (..., NULL, 0)
+ * - signal: equivalent to g_signal_connect_data (..., NULL, G_CONNECT_DEFAULT)
- * - object-signal, object_signal: equivalent to g_signal_connect_object (..., 0)
+ * - object-signal, object_signal: equivalent to g_signal_connect_object (..., G_CONNECT_DEFAULT)
  * - swapped-signal, swapped_signal: equivalent to g_signal_connect_data (..., NULL, G_CONNECT_SWAPPED)
  * - swapped_object_signal, swapped-object-signal: equivalent to g_signal_connect_object (..., G_CONNECT_SWAPPED)
  * - signal_after, signal-after: equivalent to g_signal_connect_data (..., NULL, G_CONNECT_AFTER)
@@ -3135,12 +3135,12 @@ g_object_connect (gpointer     _object,
       if (strncmp (signal_spec, "signal::", 8) == 0)
 	g_signal_connect_data (object, signal_spec + 8,
 			       callback, data, NULL,
-			       0);
+			       G_CONNECT_DEFAULT);
       else if (strncmp (signal_spec, "object_signal::", 15) == 0 ||
                strncmp (signal_spec, "object-signal::", 15) == 0)
 	g_signal_connect_object (object, signal_spec + 15,
 				 callback, data,
-				 0);
+				 G_CONNECT_DEFAULT);
       else if (strncmp (signal_spec, "swapped_signal::", 16) == 0 ||
                strncmp (signal_spec, "swapped-signal::", 16) == 0)
 	g_signal_connect_data (object, signal_spec + 16,

gobject/gsignal.h

@@ -155,9 +155,11 @@ typedef enum
 #define G_SIGNAL_FLAGS_MASK  0x1ff
 /**
  * GConnectFlags:
- * @G_CONNECT_AFTER: whether the handler should be called before or after the
+ * @G_CONNECT_DEFAULT: Default behaviour (no special flags). Since: 2.74
- *  default handler of the signal.
+ * @G_CONNECT_AFTER: If set, the handler should be called after the
- * @G_CONNECT_SWAPPED: whether the instance and data should be swapped when
+ *  default handler of the signal. Normally, the handler is called before
+ *  the default handler.
+ * @G_CONNECT_SWAPPED: If set, the instance and data should be swapped when
  *  calling the handler; see g_signal_connect_swapped() for an example.
  * 
  * The connection flags are used to specify the behaviour of a signal's 
@@ -165,6 +167,7 @@ typedef enum
  */
 typedef enum
 {
+  G_CONNECT_DEFAULT GLIB_AVAILABLE_ENUMERATOR_IN_2_74 = 0,
   G_CONNECT_AFTER	= 1 << 0,
   G_CONNECT_SWAPPED	= 1 << 1
 } GConnectFlags;
@@ -504,6 +507,8 @@ void   g_signal_chain_from_overridden_handler (gpointer           instance,
  * 
  * Returns: the handler ID, of type #gulong (always greater than 0 for successful connections)
  */
+/* Intentionally not using G_CONNECT_DEFAULT here to avoid deprecation
+ * warnings with older GLIB_VERSION_MAX_ALLOWED */
 #define g_signal_connect(instance, detailed_signal, c_handler, data) \
     g_signal_connect_data ((instance), (detailed_signal), (c_handler), (data), NULL, (GConnectFlags) 0)
 /**

gobject/tests/signals.c

@@ -1109,8 +1109,10 @@ test_destroy_target_object (void)
   sender = g_object_new (test_get_type (), NULL);
   target1 = g_object_new (test_get_type (), NULL);
   target2 = g_object_new (test_get_type (), NULL);
-  g_signal_connect_object (sender, "simple", G_CALLBACK (simple_handler1), target1, 0);
+  g_signal_connect_object (sender, "simple", G_CALLBACK (simple_handler1),
-  g_signal_connect_object (sender, "simple", G_CALLBACK (simple_handler2), target2, 0);
+                           target1, G_CONNECT_DEFAULT);
+  g_signal_connect_object (sender, "simple", G_CALLBACK (simple_handler2),
+                           target2, G_CONNECT_DEFAULT);
   g_signal_emit_by_name (sender, "simple");
   g_object_unref (sender);
 }