gobject: add GSignalGroup

Much like GBindingGroup, the GSignalGroup object allows you to connect many
signal connections for an object and connect/disconnect/block/unblock them
as a group.

This is useful when using many connections on an object to ensure that they
are properly removed when changing state or disposing a third-party
object.

This has been used for years in various GNOME projects and makes sense to
have upstream instead of multiple copies.

8 files changed, 1682 insertions, 0 deletions

diff --git a/docs/reference/gobject/gobject-docs.xml b/docs/reference/gobject/gobject-docs.xml
index 1718d9e23..aa5a9c722 100644
--- a/docs/reference/gobject/gobject-docs.xml
+++ b/docs/reference/gobject/gobject-docs.xml
@@ -81,6 +81,7 @@
       <xi:include href="xml/gparamspec.xml" />
       <xi:include href="xml/value_collection.xml" />
       <xi:include href="xml/signals.xml" />
+      <xi:include href="xml/gsignalgroup.xml" />
       <xi:include href="xml/gclosure.xml" />
       <xi:include href="xml/value_arrays.xml" />
       <xi:include href="xml/gbinding.xml" />
diff --git a/docs/reference/gobject/gobject-sections.txt b/docs/reference/gobject/gobject-sections.txt
index 2450a367d..cbab92406 100644
--- a/docs/reference/gobject/gobject-sections.txt
+++ b/docs/reference/gobject/gobject-sections.txt
@@ -1024,3 +1024,25 @@ G_IS_BINDING_GROUP
 <SUBSECTION Private>
 g_binding_group_get_type
 </SECTION>
+
+<SECTION>
+<FILE>gsignalgroup</FILE>
+GSignalGroup
+g_signal_group_block
+g_signal_group_connect
+g_signal_group_connect_after
+g_signal_group_connect_data
+g_signal_group_connect_object
+g_signal_group_connect_swapped
+g_signal_group_dup_target
+g_signal_group_get_type
+g_signal_group_new
+g_signal_group_set_target
+g_signal_group_unblock
+<SUBSECTION Standard>
+G_IS_SIGNAL_GROUP
+G_SIGNAL_GROUP
+G_TYPE_SIGNAL_GROUP
+<SUBSECTION Private>
+g_signal_group_get_type
+</SECTION>
diff --git a/glib/glib-object.h b/glib/glib-object.h
index d259a3d39..915a29901 100644
--- a/glib/glib-object.h
+++ b/glib/glib-object.h
@@ -28,6 +28,7 @@
 #include <gobject/gparam.h>
 #include <gobject/gparamspecs.h>
 #include <gobject/gsignal.h>
+#include <gobject/gsignalgroup.h>
 #include <gobject/gsourceclosure.h>
 #include <gobject/gtype.h>
 #include <gobject/gtypemodule.h>
diff --git a/gobject/gsignalgroup.c b/gobject/gsignalgroup.c
new file mode 100644
index 000000000..8feba543c
--- /dev/null
+++ b/gobject/gsignalgroup.c
@@ -0,0 +1,912 @@
+/* GObject - GLib Type, Object, Parameter and Signal Library
+ *
+ * Copyright (C) 2015-2022 Christian Hergert <christian@hergert.me>
+ * Copyright (C) 2015 Garrett Regier <garrettregier@gmail.com>
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * This library 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.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General
+ * Public License along with this library; if not, see <http://www.gnu.org/licenses/>.
+ *
+ * SPDX-License-Identifier: LGPL-2.1-or-later
+ */
+
+#include "config.h"
+#include "glib.h"
+#include "glibintl.h"
+
+#include "gparamspecs.h"
+#include "gsignalgroup.h"
+#include "gvaluetypes.h"
+
+/**
+ * SECTION:gsignalgroup
+ * @Title: GSignalGroup
+ * @Short_description: Manage a collection of signals on a GObject
+ *
+ * #GSignalGroup manages to simplify the process of connecting
+ * many signals to a #GObject as a group. As such there is no API
+ * to disconnect a signal from the group.
+ *
+ * In particular, this allows you to:
+ *
+ *  - Change the target instance, which automatically causes disconnection
+ *    of the signals from the old instance and connecting to the new instance.
+ *  - Block and unblock signals as a group
+ *  - Ensuring that blocked state transfers across target instances.
+ *
+ * One place you might want to use such a structure is with #GtkTextView and
+ * #GtkTextBuffer. Often times, you'll need to connect to many signals on
+ * #GtkTextBuffer from a #GtkTextView subclass. This allows you to create a
+ * signal group during instance construction, simply bind the
+ * #GtkTextView:buffer property to #GSignalGroup:target and connect
+ * all the signals you need. When the #GtkTextView:buffer property changes
+ * all of the signals will be transitioned correctly.
+ *
+ * Since: 2.72
+ */
+
+struct _GSignalGroup
+{
+  GObject     parent_instance;
+
+  GWeakRef    target_ref;
+  GRecMutex   mutex;
+  GPtrArray  *handlers;
+  GType       target_type;
+  gssize      block_count;
+
+  guint       has_bound_at_least_once : 1;
+};
+
+typedef struct _GSignalGroupClass
+{
+  GObjectClass parent_class;
+
+  void (*bind) (GSignalGroup *self,
+                GObject      *target);
+} GSignalGroupClass;
+
+typedef struct
+{
+  GSignalGroup *group;
+  gulong             handler_id;
+  GClosure          *closure;
+  guint              signal_id;
+  GQuark             signal_detail;
+  guint              connect_after : 1;
+} SignalHandler;
+
+G_DEFINE_TYPE (GSignalGroup, g_signal_group, G_TYPE_OBJECT)
+
+typedef enum
+{
+  PROP_TARGET = 1,
+  PROP_TARGET_TYPE,
+  LAST_PROP
+} GSignalGroupProperty;
+
+enum
+{
+  BIND,
+  UNBIND,
+  LAST_SIGNAL
+};
+
+static GParamSpec *properties[LAST_PROP];
+static guint signals[LAST_SIGNAL];
+
+static void
+g_signal_group_set_target_type (GSignalGroup *self,
+                                GType         target_type)
+{
+  g_assert (G_IS_SIGNAL_GROUP (self));
+  g_assert (g_type_is_a (target_type, G_TYPE_OBJECT));
+
+  self->target_type = target_type;
+
+  /* The class must be created at least once for the signals
+   * to be registered, otherwise g_signal_parse_name() will fail
+   */
+  if (G_TYPE_IS_INTERFACE (target_type))
+    {
+      if (g_type_default_interface_peek (target_type) == NULL)
+        g_type_default_interface_unref (g_type_default_interface_ref (target_type));
+    }
+  else
+    {
+      if (g_type_class_peek (target_type) == NULL)
+        g_type_class_unref (g_type_class_ref (target_type));
+    }
+}
+
+static void
+g_signal_group_gc_handlers (GSignalGroup *self)
+{
+  guint i;
+
+  g_assert (G_IS_SIGNAL_GROUP (self));
+
+  /*
+   * Remove any handlers for which the closures have become invalid. We do
+   * this cleanup lazily to avoid situations where we could have disposal
+   * active on both the signal group and the peer object.
+   */
+
+  for (i = self->handlers->len; i > 0; i--)
+    {
+      const SignalHandler *handler = g_ptr_array_index (self->handlers, i - 1);
+
+      g_assert (handler != NULL);
+      g_assert (handler->closure != NULL);
+
+      if (handler->closure->is_invalid)
+        g_ptr_array_remove_index (self->handlers, i - 1);
+    }
+}
+
+static void
+g_signal_group__target_weak_notify (gpointer  data,
+                                    GObject  *where_object_was)
+{
+  GSignalGroup *self = data;
+  guint i;
+
+  g_assert (G_IS_SIGNAL_GROUP (self));
+  g_assert (where_object_was != NULL);
+
+  g_rec_mutex_lock (&self->mutex);
+
+  g_weak_ref_set (&self->target_ref, NULL);
+
+  for (i = 0; i < self->handlers->len; i++)
+    {
+      SignalHandler *handler = g_ptr_array_index (self->handlers, i);
+
+      handler->handler_id = 0;
+    }
+
+  g_signal_emit (self, signals[UNBIND], 0);
+  g_object_notify_by_pspec (G_OBJECT (self), properties[PROP_TARGET]);
+
+  g_rec_mutex_unlock (&self->mutex);
+}
+
+static void
+g_signal_group_bind_handler (GSignalGroup  *self,
+                             SignalHandler *handler,
+                             GObject       *target)
+{
+  gssize i;
+
+  g_assert (self != NULL);
+  g_assert (G_IS_OBJECT (target));
+  g_assert (handler != NULL);
+  g_assert (handler->signal_id != 0);
+  g_assert (handler->closure != NULL);
+  g_assert (handler->closure->is_invalid == 0);
+  g_assert (handler->handler_id == 0);
+
+  handler->handler_id = g_signal_connect_closure_by_id (target,
+                                                        handler->signal_id,
+                                                        handler->signal_detail,
+                                                        handler->closure,
+                                                        handler->connect_after);
+
+  g_assert (handler->handler_id != 0);
+
+  for (i = 0; i < self->block_count; i++)
+    g_signal_handler_block (target, handler->handler_id);
+}
+
+static void
+g_signal_group_bind (GSignalGroup *self,
+                     GObject      *target)
+{
+  GObject *hold;
+  guint i;
+
+  g_assert (G_IS_SIGNAL_GROUP (self));
+  g_assert (!target || G_IS_OBJECT (target));
+
+  if (target == NULL)
+    return;
+
+  self->has_bound_at_least_once = TRUE;
+
+  hold = g_object_ref (target);
+
+  g_weak_ref_set (&self->target_ref, hold);
+  g_object_weak_ref (hold, g_signal_group__target_weak_notify, self);
+
+  g_signal_group_gc_handlers (self);
+
+  for (i = 0; i < self->handlers->len; i++)
+    {
+      SignalHandler *handler = g_ptr_array_index (self->handlers, i);
+
+      g_signal_group_bind_handler (self, handler, hold);
+    }
+
+  g_signal_emit (self, signals [BIND], 0, hold);
+
+  g_object_unref (hold);
+}
+
+static void
+g_signal_group_unbind (GSignalGroup *self)
+{
+  GObject *target;
+  guint i;
+
+  g_return_if_fail (G_IS_SIGNAL_GROUP (self));
+
+  target = g_weak_ref_get (&self->target_ref);
+
+  /*
+   * Target may be NULL by this point, as we got notified of its destruction.
+   * However, if we're early enough, we may get a full reference back and can
+   * cleanly disconnect our connections.
+   */
+
+  if (target != NULL)
+    {
+      g_weak_ref_set (&self->target_ref, NULL);
+
+      /*
+       * Let go of our weak reference now that we have a full reference
+       * for the life of this function.
+       */
+      g_object_weak_unref (target,
+                           g_signal_group__target_weak_notify,
+                           self);
+    }
+
+  g_signal_group_gc_handlers (self);
+
+  for (i = 0; i < self->handlers->len; i++)
+    {
+      SignalHandler *handler;
+      gulong handler_id;
+
+      handler = g_ptr_array_index (self->handlers, i);
+
+      g_assert (handler != NULL);
+      g_assert (handler->signal_id != 0);
+      g_assert (handler->closure != NULL);
+
+      handler_id = handler->handler_id;
+      handler->handler_id = 0;
+
+      /*
+       * If @target is NULL, we lost a race to cleanup the weak
+       * instance and the signal connections have already been
+       * finalized and therefore nothing to do.
+       */
+
+      if (target != NULL && handler_id != 0)
+        g_signal_handler_disconnect (target, handler_id);
+    }
+
+  g_signal_emit (self, signals [UNBIND], 0);
+
+  g_clear_object (&target);
+}
+
+static gboolean
+g_signal_group_check_target_type (GSignalGroup *self,
+                                  gpointer      target)
+{
+  if ((target != NULL) &&
+      !g_type_is_a (G_OBJECT_TYPE (target), self->target_type))
+    {
+      g_critical ("Failed to set GSignalGroup of target type %s "
+                  "using target %p of type %s",
+                  g_type_name (self->target_type),
+                  target, G_OBJECT_TYPE_NAME (target));
+      return FALSE;
+    }
+
+  return TRUE;
+}
+
+/**
+ * g_signal_group_block:
+ * @self: the #GSignalGroup
+ *
+ * Blocks all signal handlers managed by @self so they will not
+ * be called during any signal emissions. Must be unblocked exactly
+ * the same number of times it has been blocked to become active again.
+ *
+ * This blocked state will be kept across changes of the target instance.
+ *
+ * Since: 2.72
+ */
+void
+g_signal_group_block (GSignalGroup *self)
+{
+  GObject *target;
+  guint i;
+
+  g_return_if_fail (G_IS_SIGNAL_GROUP (self));
+  g_return_if_fail (self->block_count >= 0);
+
+  g_rec_mutex_lock (&self->mutex);
+
+  self->block_count++;
+
+  target = g_weak_ref_get (&self->target_ref);
+
+  if (target == NULL)
+    goto unlock;
+
+  for (i = 0; i < self->handlers->len; i++)
+    {
+      const SignalHandler *handler = g_ptr_array_index (self->handlers, i);
+
+      g_assert (handler != NULL);
+      g_assert (handler->signal_id != 0);
+      g_assert (handler->closure != NULL);
+      g_assert (handler->handler_id != 0);
+
+      g_signal_handler_block (target, handler->handler_id);
+    }
+
+  g_object_unref (target);
+
+unlock:
+  g_rec_mutex_unlock (&self->mutex);
+}
+
+/**
+ * g_signal_group_unblock:
+ * @self: the #GSignalGroup
+ *
+ * Unblocks all signal handlers managed by @self so they will be
+ * called again during any signal emissions unless it is blocked
+ * again. Must be unblocked exactly the same number of times it
+ * has been blocked to become active again.
+ *
+ * Since: 2.72
+ */
+void
+g_signal_group_unblock (GSignalGroup *self)
+{
+  GObject *target;
+  guint i;
+
+  g_return_if_fail (G_IS_SIGNAL_GROUP (self));
+  g_return_if_fail (self->block_count > 0);
+
+  g_rec_mutex_lock (&self->mutex);
+
+  self->block_count--;
+
+  target = g_weak_ref_get (&self->target_ref);
+  if (target == NULL)
+    goto unlock;
+
+  for (i = 0; i < self->handlers->len; i++)
+    {
+      const SignalHandler *handler = g_ptr_array_index (self->handlers, i);
+
+      g_assert (handler != NULL);
+      g_assert (handler->signal_id != 0);
+      g_assert (handler->closure != NULL);
+      g_assert (handler->handler_id != 0);
+
+      g_signal_handler_unblock (target, handler->handler_id);
+    }
+
+  g_object_unref (target);
+
+unlock:
+  g_rec_mutex_unlock (&self->mutex);
+}
+
+/**
+ * g_signal_group_dup_target:
+ * @self: the #GSignalGroup
+ *
+ * Gets the target instance used when connecting signals.
+ *
+ * Returns: (nullable) (transfer full) (type GObject): The target instance
+ *
+ * Since: 2.72
+ */
+gpointer
+g_signal_group_dup_target (GSignalGroup *self)
+{
+  GObject *target;
+
+  g_return_val_if_fail (G_IS_SIGNAL_GROUP (self), NULL);
+
+  g_rec_mutex_lock (&self->mutex);
+  target = g_weak_ref_get (&self->target_ref);
+  g_rec_mutex_unlock (&self->mutex);
+
+  return target;
+}
+
+/**
+ * g_signal_group_set_target:
+ * @self: the #GSignalGroup.
+ * @target: (nullable) (type GObject) (transfer none): The target instance used
+ *     when connecting signals.
+ *
+ * Sets the target instance used when connecting signals. Any signal
+ * that has been registered with g_signal_group_connect_object() or
+ * similar functions will be connected to this object.
+ *
+ * If the target instance was previously set, signals will be
+ * disconnected from that object prior to connecting to @target.
+ *
+ * Since: 2.72
+ */
+void
+g_signal_group_set_target (GSignalGroup *self,
+                           gpointer      target)
+{
+  GObject *object;
+
+  g_return_if_fail (G_IS_SIGNAL_GROUP (self));
+
+  g_rec_mutex_lock (&self->mutex);
+
+  object = g_weak_ref_get (&self->target_ref);
+
+  if (object == (GObject *)target)
+    goto cleanup;
+
+  if (!g_signal_group_check_target_type (self, target))
+    goto cleanup;
+
+  /* Only emit unbind if we've ever called bind */
+  if (self->has_bound_at_least_once)
+    g_signal_group_unbind (self);
+
+  g_signal_group_bind (self, target);
+
+  g_object_notify_by_pspec (G_OBJECT (self), properties[PROP_TARGET]);
+
+cleanup:
+  g_clear_object (&object);
+  g_rec_mutex_unlock (&self->mutex);
+}
+
+static void
+signal_handler_free (gpointer data)
+{
+  SignalHandler *handler = data;
+
+  if (handler->closure != NULL)
+    g_closure_invalidate (handler->closure);
+
+  handler->handler_id = 0;
+  handler->signal_id = 0;
+  handler->signal_detail = 0;
+  g_clear_pointer (&handler->closure, g_closure_unref);
+  g_slice_free (SignalHandler, handler);
+}
+
+static void
+g_signal_group_constructed (GObject *object)
+{
+  GSignalGroup *self = (GSignalGroup *)object;
+  GObject *target;
+
+  g_rec_mutex_lock (&self->mutex);
+
+  target = g_weak_ref_get (&self->target_ref);
+  if (!g_signal_group_check_target_type (self, target))
+    g_signal_group_set_target (self, NULL);
+
+  G_OBJECT_CLASS (g_signal_group_parent_class)->constructed (object);
+
+  g_clear_object (&target);
+
+  g_rec_mutex_unlock (&self->mutex);
+}
+
+static void
+g_signal_group_dispose (GObject *object)
+{
+  GSignalGroup *self = (GSignalGroup *)object;
+
+  g_rec_mutex_lock (&self->mutex);
+
+  g_signal_group_gc_handlers (self);
+
+  if (self->has_bound_at_least_once)
+    g_signal_group_unbind (self);
+
+  g_clear_pointer (&self->handlers, g_ptr_array_unref);
+
+  g_rec_mutex_unlock (&self->mutex);
+
+  G_OBJECT_CLASS (g_signal_group_parent_class)->dispose (object);
+}
+
+static void
+g_signal_group_finalize (GObject *object)
+{
+  GSignalGroup *self = (GSignalGroup *)object;
+
+  g_weak_ref_clear (&self->target_ref);
+  g_rec_mutex_clear (&self->mutex);
+
+  G_OBJECT_CLASS (g_signal_group_parent_class)->finalize (object);
+}
+
+static void
+g_signal_group_get_property (GObject    *object,
+                             guint       prop_id,
+                             GValue     *value,
+                             GParamSpec *pspec)
+{
+  GSignalGroup *self = G_SIGNAL_GROUP (object);
+
+  switch ((GSignalGroupProperty) prop_id)
+    {
+    case PROP_TARGET:
+      g_value_take_object (value, g_signal_group_dup_target (self));
+      break;
+
+    case PROP_TARGET_TYPE:
+      g_value_set_gtype (value, self->target_type);
+      break;
+
+    default:
+      G_OBJECT_WARN_INVALID_PROPERTY_ID (object, prop_id, pspec);
+    }
+}
+
+static void
+g_signal_group_set_property (GObject      *object,
+                             guint         prop_id,
+                             const GValue *value,
+                             GParamSpec   *pspec)
+{
+  GSignalGroup *self = G_SIGNAL_GROUP (object);
+
+  switch ((GSignalGroupProperty) prop_id)
+    {
+    case PROP_TARGET:
+      g_signal_group_set_target (self, g_value_get_object (value));
+      break;
+
+    case PROP_TARGET_TYPE:
+      g_signal_group_set_target_type (self, g_value_get_gtype (value));
+      break;
+
+    default:
+      G_OBJECT_WARN_INVALID_PROPERTY_ID (object, prop_id, pspec);
+    }
+}
+
+static void
+g_signal_group_class_init (GSignalGroupClass *klass)
+{
+  GObjectClass *object_class = G_OBJECT_CLASS (klass);
+
+  object_class->constructed = g_signal_group_constructed;
+  object_class->dispose = g_signal_group_dispose;
+  object_class->finalize = g_signal_group_finalize;
+  object_class->get_property = g_signal_group_get_property;
+  object_class->set_property = g_signal_group_set_property;
+
+  /**
+   * GSignalGroup:target
+   *
+   * The target instance used when connecting signals.
+   *
+   * Since: 2.72
+   */
+  properties[PROP_TARGET] =
+      g_param_spec_object ("target",
+                           "Target",
+                           "The target instance used when connecting signals.",
+                           G_TYPE_OBJECT,
+                           (G_PARAM_READWRITE | G_PARAM_EXPLICIT_NOTIFY | G_PARAM_STATIC_STRINGS));
+
+  /**
+   * GSignalGroup:target-type
+   *
+   * The #GType of the target property.
+   *
+   * Since: 2.72
+   */
+  properties[PROP_TARGET_TYPE] =
+      g_param_spec_gtype ("target-type",
+                          "Target Type",
+                          "The GType of the target property.",
+                          G_TYPE_OBJECT,
+                          (G_PARAM_READWRITE | G_PARAM_CONSTRUCT_ONLY | G_PARAM_STATIC_STRINGS));
+
+  g_object_class_install_properties (object_class, LAST_PROP, properties);
+
+  /**
+   * GSignalGroup::bind:
+   * @self: the #GSignalGroup
+   * @instance: a #GObject containing the new value for #GSignalGroup:target
+   *
+   * This signal is emitted when #GSignalGroup:target is set to a new value
+   * other than %NULL. It is similar to #GObject::notify on `target` except it
+   * will not emit when #GSignalGroup:target is %NULL and also allows for
+   * receiving the #GObject without a data-race.
+   *
+   * Since: 2.72
+   */
+  signals[BIND] =
+      g_signal_new ("bind",
+                    G_TYPE_FROM_CLASS (klass),
+                    G_SIGNAL_RUN_LAST,
+                    0,
+                    NULL, NULL, NULL,
+                    G_TYPE_NONE,
+                    1,
+                    G_TYPE_OBJECT);
+
+  /**
+   * GSignalGroup::unbind:
+   * @self: a #GSignalGroup
+   *
+   * This signal is emitted when the target instance of @self is set to a
+   * new #GObject.
+   *
+   * This signal will only be emitted if the previous target of @self is
+   * non-%NULL.
+   *
+   * Since: 2.72
+   */
+  signals[UNBIND] =
+      g_signal_new ("unbind",
+                    G_TYPE_FROM_CLASS (klass),
+                    G_SIGNAL_RUN_LAST,
+                    0,
+                    NULL, NULL, NULL,
+                    G_TYPE_NONE,
+                    0);
+}
+
+static void
+g_signal_group_init (GSignalGroup *self)
+{
+  g_rec_mutex_init (&self->mutex);
+  self->handlers = g_ptr_array_new_with_free_func (signal_handler_free);
+  self->target_type = G_TYPE_OBJECT;
+}
+
+/**
+ * g_signal_group_new:
+ * @target_type: the #GType of the target instance.
+ *
+ * Creates a new #GSignalGroup for target instances of @target_type.
+ *
+ * Returns: (transfer full): a new #GSignalGroup
+ *
+ * Since: 2.72
+ */
+GSignalGroup *
+g_signal_group_new (GType target_type)
+{
+  g_return_val_if_fail (g_type_is_a (target_type, G_TYPE_OBJECT), NULL);
+
+  return g_object_new (G_TYPE_SIGNAL_GROUP,
+                       "target-type", target_type,
+                       NULL);
+}
+
+static void
+g_signal_group_connect_full (GSignalGroup   *self,
+                             const gchar    *detailed_signal,
+                             GCallback       c_handler,
+                             gpointer        data,
+                             GClosureNotify  notify,
+                             GConnectFlags   flags,
+                             gboolean        is_object)
+{
+  GObject *target;
+  SignalHandler *handler;
+  GClosure *closure;
+  guint signal_id;
+  GQuark signal_detail;
+
+  g_return_if_fail (G_IS_SIGNAL_GROUP (self));
+  g_return_if_fail (detailed_signal != NULL);
+  g_return_if_fail (g_signal_parse_name (detailed_signal, self->target_type,
+                                         &signal_id, &signal_detail, TRUE) != 0);
+  g_return_if_fail (c_handler != NULL);
+  g_return_if_fail (!is_object || G_IS_OBJECT (data));
+
+  g_rec_mutex_lock (&self->mutex);
+
+  if (self->has_bound_at_least_once)
+    {
+      g_critical ("Cannot add signals after setting target");
+      g_rec_mutex_unlock (&self->mutex);
+      return;
+    }
+
+  if ((flags & G_CONNECT_SWAPPED) != 0)
+    closure = g_cclosure_new_swap (c_handler, data, notify);
+  else
+    closure = g_cclosure_new (c_handler, data, notify);
+
+  handler = g_slice_new0 (SignalHandler);
+  handler->group = self;
+  handler->signal_id = signal_id;
+  handler->signal_detail = signal_detail;
+  handler->closure = g_closure_ref (closure);
+  handler->connect_after = ((flags & G_CONNECT_AFTER) != 0);
+
+  g_closure_sink (closure);
+
+  if (is_object)
+    {
+      /* Set closure->is_invalid when data is disposed. We only track this to avoid
+       * reconnecting in the future. However, we do a round of cleanup when ever we
+       * connect a new object or the target changes to GC the old handlers.
+       */
+      g_object_watch_closure (data, closure);
+    }
+
+  g_ptr_array_add (self->handlers, handler);
+
+  target = g_weak_ref_get (&self->target_ref);
+
+  if (target != NULL)
+    {
+      g_signal_group_bind_handler (self, handler, target);
+      g_object_unref (target);
+    }
+
+  /* Lazily remove any old handlers on connect */
+  g_signal_group_gc_handlers (self);
+
+  g_rec_mutex_unlock (&self->mutex);
+}
+
+/**
+ * g_signal_group_connect_object: (skip)
+ * @self: a #GSignalGroup
+ * @detailed_signal: a string of the form `signal-name` with optional `::signal-detail`
+ * @c_handler: (scope notified): the #GCallback to connect
+ * @object: (not nullable) (transfer none): the #GObject to pass as data to @c_handler calls
+ * @flags: #GConnectFlags for the signal connection
+ *
+ * Connects @c_handler to the signal @detailed_signal on #GSignalGroup:target.
+ *
+ * Ensures that the @object stays alive during the call to @c_handler
+ * by temporarily adding a reference count. When the @object is destroyed
+ * the signal handler will automatically be removed.
+ *
+ * You cannot connect a signal handler after #GSignalGroup:target has been set.
+ *
+ * Since: 2.72
+ */
+void
+g_signal_group_connect_object (GSignalGroup  *self,
+                               const gchar   *detailed_signal,
+                               GCallback      c_handler,
+                               gpointer       object,
+                               GConnectFlags  flags)
+{
+  g_return_if_fail (G_IS_OBJECT (object));
+
+  g_signal_group_connect_full (self, detailed_signal, c_handler, object, NULL,
+                               flags, TRUE);
+}
+
+/**
+ * g_signal_group_connect_data:
+ * @self: a #GSignalGroup
+ * @detailed_signal: a string of the form "signal-name::detail"
+ * @c_handler: (scope notified) (closure data) (destroy notify): the #GCallback to connect
+ * @data: the data to pass to @c_handler calls
+ * @notify: function to be called when disposing of @self
+ * @flags: the flags used to create the signal connection
+ *
+ * Connects @c_handler to the signal @detailed_signal
+ * on the target instance of @self.
+ *
+ * You cannot connect a signal handler after #GSignalGroup:target has been set.
+ *
+ * Since: 2.72
+ */
+void
+g_signal_group_connect_data (GSignalGroup   *self,
+                             const gchar    *detailed_signal,
+                             GCallback       c_handler,
+                             gpointer        data,
+                             GClosureNotify  notify,
+                             GConnectFlags   flags)
+{
+  g_signal_group_connect_full (self, detailed_signal, c_handler, data, notify,
+                               flags, FALSE);
+}
+
+/**
+ * g_signal_group_connect: (skip)
+ * @self: a #GSignalGroup
+ * @detailed_signal: a string of the form "signal-name::detail"
+ * @c_handler: (scope notified): the #GCallback to connect
+ * @data: the data to pass to @c_handler calls
+ *
+ * Connects @c_handler to the signal @detailed_signal
+ * on the target instance of @self.
+ *
+ * You cannot connect a signal handler after #GSignalGroup:target has been set.
+ *
+ * Since: 2.72
+ */
+void
+g_signal_group_connect (GSignalGroup *self,
+                        const gchar  *detailed_signal,
+                        GCallback     c_handler,
+                        gpointer      data)
+{
+  g_signal_group_connect_full (self, detailed_signal, c_handler, data, NULL,
+                               0, FALSE);
+}
+
+/**
+ * g_signal_group_connect_after: (skip)
+ * @self: a #GSignalGroup
+ * @detailed_signal: a string of the form "signal-name::detail"
+ * @c_handler: (scope notified): the #GCallback to connect
+ * @data: the data to pass to @c_handler calls
+ *
+ * Connects @c_handler to the signal @detailed_signal
+ * on the target instance of @self.
+ *
+ * The @c_handler will be called after the default handler of the signal.
+ *
+ * You cannot connect a signal handler after #GSignalGroup:target has been set.
+ *
+ * Since: 2.72
+ */
+void
+g_signal_group_connect_after (GSignalGroup *self,
+                              const gchar  *detailed_signal,
+                              GCallback     c_handler,
+                              gpointer      data)
+{
+  g_signal_group_connect_full (self, detailed_signal, c_handler,
+                               data, NULL, G_CONNECT_AFTER, FALSE);
+}
+
+/**
+ * g_signal_group_connect_swapped:
+ * @self: a #GSignalGroup
+ * @detailed_signal: a string of the form "signal-name::detail"
+ * @c_handler: (scope async): the #GCallback to connect
+ * @data: the data to pass to @c_handler calls
+ *
+ * Connects @c_handler to the signal @detailed_signal
+ * on the target instance of @self.
+ *
+ * The instance on which the signal is emitted and @data
+ * will be swapped when calling @c_handler.
+ *
+ * You cannot connect a signal handler after #GSignalGroup:target has been set.
+ *
+ * Since: 2.72
+ */
+void
+g_signal_group_connect_swapped (GSignalGroup *self,
+                                const gchar  *detailed_signal,
+                                GCallback     c_handler,
+                                gpointer      data)
+{
+  g_signal_group_connect_full (self, detailed_signal, c_handler, data, NULL,
+                               G_CONNECT_SWAPPED, FALSE);
+}
diff --git a/gobject/gsignalgroup.h b/gobject/gsignalgroup.h
new file mode 100644
index 000000000..c82a5cd4f
--- /dev/null
+++ b/gobject/gsignalgroup.h
@@ -0,0 +1,93 @@
+/* GObject - GLib Type, Object, Parameter and Signal Library
+ *
+ * Copyright (C) 2015-2022 Christian Hergert <christian@hergert.me>
+ * Copyright (C) 2015 Garrett Regier <garrettregier@gmail.com>
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * This library 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.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General
+ * Public License along with this library; if not, see <http://www.gnu.org/licenses/>.
+ *
+ * SPDX-License-Identifier: LGPL-2.1-or-later
+ */
+
+#ifndef __G_SIGNAL_GROUP_H__
+#define __G_SIGNAL_GROUP_H__
+
+#if !defined (__GLIB_GOBJECT_H_INSIDE__) && !defined (GOBJECT_COMPILATION)
+#error "Only <glib-object.h> can be included directly."
+#endif
+
+#include <glib.h>
+#include <gobject/gobject.h>
+#include <gobject/gsignal.h>
+
+G_BEGIN_DECLS
+
+#define G_SIGNAL_GROUP(obj)    (G_TYPE_CHECK_INSTANCE_CAST ((obj), G_TYPE_SIGNAL_GROUP, GSignalGroup))
+#define G_IS_SIGNAL_GROUP(obj) (G_TYPE_CHECK_INSTANCE_TYPE ((obj), G_TYPE_SIGNAL_GROUP))
+#define G_TYPE_SIGNAL_GROUP    (g_signal_group_get_type())
+
+/**
+ * GSignalGroup:
+ *
+ * #GSignalGroup is an opaque structure whose members
+ * cannot be accessed directly.
+ *
+ * Since: 2.72
+ */
+typedef struct _GSignalGroup GSignalGroup;
+
+GLIB_AVAILABLE_IN_2_72
+GType         g_signal_group_get_type        (void) G_GNUC_CONST;
+GLIB_AVAILABLE_IN_2_72
+GSignalGroup *g_signal_group_new             (GType           target_type);
+GLIB_AVAILABLE_IN_2_72
+void          g_signal_group_set_target      (GSignalGroup   *self,
+                                              gpointer        target);
+GLIB_AVAILABLE_IN_2_72
+gpointer      g_signal_group_dup_target      (GSignalGroup   *self);
+GLIB_AVAILABLE_IN_2_72
+void          g_signal_group_block           (GSignalGroup   *self);
+GLIB_AVAILABLE_IN_2_72
+void          g_signal_group_unblock         (GSignalGroup   *self);
+GLIB_AVAILABLE_IN_2_72
+void          g_signal_group_connect_object  (GSignalGroup   *self,
+                                              const gchar    *detailed_signal,
+                                              GCallback       c_handler,
+                                              gpointer        object,
+                                              GConnectFlags   flags);
+GLIB_AVAILABLE_IN_2_72
+void          g_signal_group_connect_data    (GSignalGroup   *self,
+                                              const gchar    *detailed_signal,
+                                              GCallback       c_handler,
+                                              gpointer        data,
+                                              GClosureNotify  notify,
+                                              GConnectFlags   flags);
+GLIB_AVAILABLE_IN_2_72
+void          g_signal_group_connect         (GSignalGroup   *self,
+                                              const gchar    *detailed_signal,
+                                              GCallback       c_handler,
+                                              gpointer        data);
+GLIB_AVAILABLE_IN_2_72
+void          g_signal_group_connect_after   (GSignalGroup   *self,
+                                              const gchar    *detailed_signal,
+                                              GCallback       c_handler,
+                                              gpointer        data);
+GLIB_AVAILABLE_IN_2_72
+void          g_signal_group_connect_swapped (GSignalGroup   *self,
+                                              const gchar    *detailed_signal,
+                                              GCallback       c_handler,
+                                              gpointer        data);
+
+G_END_DECLS
+
+#endif /* __G_SIGNAL_GROUP_H__ */
diff --git a/gobject/meson.build b/gobject/meson.build
index 48bd87601..74feb09d9 100644
--- a/gobject/meson.build
+++ b/gobject/meson.build
@@ -11,6 +11,7 @@ gobject_install_headers = files(
   'gparam.h',
   'gparamspecs.h',
   'gsignal.h',
+  'gsignalgroup.h',
   'gsourceclosure.h',
   'gtype.h',
   'gtypemodule.h',
@@ -35,6 +36,7 @@ gobject_sources = files(
   'gparam.c',
   'gparamspecs.c',
   'gsignal.c',
+  'gsignalgroup.c',
   'gsourceclosure.c',
   'gtype.c',
   'gtypemodule.c',
diff --git a/gobject/tests/meson.build b/gobject/tests/meson.build
index 901590471..8d568f00e 100644
--- a/gobject/tests/meson.build
+++ b/gobject/tests/meson.build
@@ -54,6 +54,7 @@ gobject_tests = {
   'signals' : {
     'source' : ['signals.c', marshalers_h, marshalers_c],
   },
+  'signalgroup' : {},
   'testing' : {},
   'type-flags' : {},
 }
diff --git a/gobject/tests/signalgroup.c b/gobject/tests/signalgroup.c
new file mode 100644
index 000000000..5d1f17a81
--- /dev/null
+++ b/gobject/tests/signalgroup.c
@@ -0,0 +1,650 @@
+/* GObject - GLib Type, Object, Parameter and Signal Library
+ *
+ * Copyright (C) 2015-2022 Christian Hergert <christian@hergert.me>
+ * Copyright (C) 2015 Garrett Regier <garrettregier@gmail.com>
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * This library 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.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General
+ * Public License along with this library; if not, see <http://www.gnu.org/licenses/>.
+ *
+ * SPDX-License-Identifier: LGPL-2.1-or-later
+ */
+
+#include <glib-object.h>
+
+G_DECLARE_FINAL_TYPE (SignalTarget, signal_target, TEST, SIGNAL_TARGET, GObject)
+
+struct _SignalTarget
+{
+  GObject parent_instance;
+};
+
+G_DEFINE_TYPE (SignalTarget, signal_target, G_TYPE_OBJECT)
+
+static G_DEFINE_QUARK (detail, signal_detail);
+
+enum {
+  THE_SIGNAL,
+  NEVER_EMITTED,
+  LAST_SIGNAL
+};
+
+static guint signals[LAST_SIGNAL];
+
+static void
+signal_target_class_init (SignalTargetClass *klass)
+{
+  signals[THE_SIGNAL] =
+      g_signal_new ("the-signal",
+                    G_TYPE_FROM_CLASS (klass),
+                    G_SIGNAL_RUN_LAST | G_SIGNAL_DETAILED,
+                    0,
+                    NULL, NULL, NULL,
+                    G_TYPE_NONE,
+                    1,
+                    G_TYPE_OBJECT);
+
+  signals[NEVER_EMITTED] =
+      g_signal_new ("never-emitted",
+                    G_TYPE_FROM_CLASS (klass),
+                    G_SIGNAL_RUN_LAST,
+                    0,
+                    NULL, NULL, NULL,
+                    G_TYPE_NONE,
+                    1,
+                    G_TYPE_OBJECT);
+}
+
+static void
+signal_target_init (SignalTarget *self)
+{
+}
+
+static gint global_signal_calls;
+static gint global_weak_notify_called;
+
+static void
+connect_before_cb (SignalTarget *target,
+                   GSignalGroup *group,
+                   gint         *signal_calls)
+{
+  SignalTarget *readback;
+
+  g_assert_true (TEST_IS_SIGNAL_TARGET (target));
+  g_assert_true (G_IS_SIGNAL_GROUP (group));
+  g_assert_nonnull (signal_calls);
+  g_assert_true (signal_calls == &global_signal_calls);
+
+  readback = g_signal_group_dup_target (group);
+  g_assert_true (readback == target);
+  g_object_unref (readback);
+
+  *signal_calls += 1;
+}
+
+static void
+connect_after_cb (SignalTarget *target,
+                  GSignalGroup *group,
+                  gint         *signal_calls)
+{
+  SignalTarget *readback;
+
+  g_assert_true (TEST_IS_SIGNAL_TARGET (target));
+  g_assert_true (G_IS_SIGNAL_GROUP (group));
+  g_assert_nonnull (signal_calls);
+  g_assert_true (signal_calls == &global_signal_calls);
+
+  readback = g_signal_group_dup_target (group);
+  g_assert_true (readback == target);
+  g_object_unref (readback);
+
+  g_assert_cmpint (*signal_calls, ==, 4);
+  *signal_calls += 1;
+}
+
+static void
+connect_swapped_cb (gint         *signal_calls,
+                    GSignalGroup *group,
+                    SignalTarget *target)
+{
+  SignalTarget *readback;
+
+  g_assert_true (signal_calls != NULL);
+  g_assert_true (signal_calls == &global_signal_calls);
+  g_assert_true (G_IS_SIGNAL_GROUP (group));
+  g_assert_true (TEST_IS_SIGNAL_TARGET (target));
+
+  readback = g_signal_group_dup_target (group);
+  g_assert_true (readback == target);
+  g_object_unref (readback);
+
+  *signal_calls += 1;
+}
+
+static void
+connect_object_cb (SignalTarget *target,
+                   GSignalGroup *group,
+                   GObject      *object)
+{
+  SignalTarget *readback;
+  gint *signal_calls;
+
+  g_assert_true (TEST_IS_SIGNAL_TARGET (target));
+  g_assert_true (G_IS_SIGNAL_GROUP (group));
+  g_assert_true (G_IS_OBJECT (object));
+
+  readback = g_signal_group_dup_target (group);
+  g_assert_true (readback == target);
+  g_object_unref (readback);
+
+  signal_calls = g_object_get_data (object, "signal-calls");
+  g_assert_nonnull (signal_calls);
+  g_assert_true (signal_calls == &global_signal_calls);
+
+  *signal_calls += 1;
+}
+
+static void
+connect_bad_detail_cb (SignalTarget *target,
+                       GSignalGroup *group,
+                       GObject      *object)
+{
+  g_error ("This detailed signal is never emitted!");
+}
+
+static void
+connect_never_emitted_cb (SignalTarget *target,
+                          gboolean     *weak_notify_called)
+{
+  g_error ("This signal is never emitted!");
+}
+
+static void
+connect_data_notify_cb (gboolean *weak_notify_called,
+                        GClosure *closure)
+{
+  g_assert_nonnull (weak_notify_called);
+  g_assert_true (weak_notify_called == &global_weak_notify_called);
+  g_assert_nonnull (closure);
+
+  g_assert_false (*weak_notify_called);
+  *weak_notify_called = TRUE;
+}
+
+static void
+connect_data_weak_notify_cb (gboolean     *weak_notify_called,
+                             GSignalGroup *group)
+{
+  g_assert_nonnull (weak_notify_called);
+  g_assert_true (weak_notify_called == &global_weak_notify_called);
+  g_assert_true (G_IS_SIGNAL_GROUP (group));
+
+  g_assert_true (*weak_notify_called);
+}
+
+static void
+connect_all_signals (GSignalGroup *group)
+{
+  GObject *object;
+
+  /* Check that these are called in the right order */
+  g_signal_group_connect (group,
+                          "the-signal",
+                          G_CALLBACK (connect_before_cb),
+                          &global_signal_calls);
+  g_signal_group_connect_after (group,
+                                "the-signal",
+                                G_CALLBACK (connect_after_cb),
+                                &global_signal_calls);
+
+  /* Check that this is called with the arguments swapped */
+  g_signal_group_connect_swapped (group,
+                                  "the-signal",
+                                  G_CALLBACK (connect_swapped_cb),
+                                  &global_signal_calls);
+
+  /* Check that this is called with the arguments swapped */
+  object = g_object_new (G_TYPE_OBJECT, NULL);
+  g_object_set_data (object, "signal-calls", &global_signal_calls);
+  g_signal_group_connect_object (group,
+                                 "the-signal",
+                                 G_CALLBACK (connect_object_cb),
+                                 object,
+                                 0);
+  g_object_weak_ref (G_OBJECT (group),
+                     (GWeakNotify)g_object_unref,
+                     object);
+
+  /* Check that a detailed signal is handled correctly */
+  g_signal_group_connect (group,
+                          "the-signal::detail",
+                          G_CALLBACK (connect_before_cb),
+                          &global_signal_calls);
+  g_signal_group_connect (group,
+                          "the-signal::bad-detail",
+                          G_CALLBACK (connect_bad_detail_cb),
+                          NULL);
+
+  /* Check that the notify is called correctly */
+  global_weak_notify_called = FALSE;
+  g_signal_group_connect_data (group,
+                               "never-emitted",
+                               G_CALLBACK (connect_never_emitted_cb),
+                               &global_weak_notify_called,
+                               (GClosureNotify)connect_data_notify_cb,
+                               0);
+  g_object_weak_ref (G_OBJECT (group),
+                     (GWeakNotify)connect_data_weak_notify_cb,
+                     &global_weak_notify_called);
+}
+
+static void
+assert_signals (SignalTarget *target,
+                GSignalGroup *group,
+                gboolean      success)
+{
+  g_assert (TEST_IS_SIGNAL_TARGET (target));
+  g_assert (group == NULL || G_IS_SIGNAL_GROUP (group));
+
+  global_signal_calls = 0;
+  g_signal_emit (target, signals[THE_SIGNAL],
+                 signal_detail_quark (), group);
+  g_assert_cmpint (global_signal_calls, ==, success ? 5 : 0);
+}
+
+static void
+dummy_handler (void)
+{
+}
+
+static void
+test_signal_group_invalid (void)
+{
+  GObject *invalid_target = g_object_new (G_TYPE_OBJECT, NULL);
+  SignalTarget *target = g_object_new (signal_target_get_type (), NULL);
+  GSignalGroup *group = g_signal_group_new (signal_target_get_type ());
+
+  /* Invalid Target Type */
+  g_test_expect_message (G_LOG_DOMAIN, G_LOG_LEVEL_CRITICAL,
+                         "*g_type_is_a*G_TYPE_OBJECT*");
+  g_signal_group_new (G_TYPE_DATE_TIME);
+  g_test_assert_expected_messages ();
+
+  /* Invalid Target */
+  g_test_expect_message (G_LOG_DOMAIN, G_LOG_LEVEL_CRITICAL,
+                         "*Failed to set GSignalGroup of target type SignalTarget using target * of type GObject*");
+  g_signal_group_set_target (group, invalid_target);
+  g_assert_finalize_object (group);
+  g_test_assert_expected_messages ();
+
+  /* Invalid Signal Name */
+  g_test_expect_message (G_LOG_DOMAIN, G_LOG_LEVEL_CRITICAL,
+                         "*g_signal_parse_name*");
+  group = g_signal_group_new (signal_target_get_type ());
+  g_signal_group_connect (group,
+                          "does-not-exist",
+                          G_CALLBACK (connect_before_cb),
+                          NULL);
+  g_test_assert_expected_messages ();
+  g_assert_finalize_object (group);
+
+  /* Invalid Callback */
+  g_test_expect_message (G_LOG_DOMAIN, G_LOG_LEVEL_CRITICAL,
+                         "*c_handler != NULL*");
+  group = g_signal_group_new (signal_target_get_type ());
+  g_signal_group_connect (group,
+                          "the-signal",
+                          G_CALLBACK (NULL),
+                          NULL);
+  g_test_assert_expected_messages ();
+  g_assert_finalize_object (group);
+
+  /* Connecting after setting target */
+  g_test_expect_message (G_LOG_DOMAIN, G_LOG_LEVEL_CRITICAL,
+                         "*Cannot add signals after setting target*");
+  group = g_signal_group_new (signal_target_get_type ());
+  g_signal_group_set_target (group, target);
+  g_signal_group_connect (group,
+                          "the-signal",
+                          G_CALLBACK (dummy_handler),
+                          NULL);
+  g_test_assert_expected_messages ();
+  g_assert_finalize_object (group);
+
+  g_assert_finalize_object (target);
+  g_assert_finalize_object (invalid_target);
+}
+
+static void
+test_signal_group_simple (void)
+{
+  SignalTarget *target;
+  GSignalGroup *group;
+  SignalTarget *readback;
+
+  /* Set the target before connecting the signals */
+  group = g_signal_group_new (signal_target_get_type ());
+  target = g_object_new (signal_target_get_type (), NULL);
+  g_assert_null (g_signal_group_dup_target (group));
+  g_signal_group_set_target (group, target);
+  readback = g_signal_group_dup_target (group);
+  g_assert_true (readback == target);
+  g_object_unref (readback);
+  g_assert_finalize_object (group);
+  assert_signals (target, NULL, FALSE);
+  g_assert_finalize_object (target);
+
+  group = g_signal_group_new (signal_target_get_type ());
+  target = g_object_new (signal_target_get_type (), NULL);
+  connect_all_signals (group);
+  g_signal_group_set_target (group, target);
+  assert_signals (target, group, TRUE);
+  g_assert_finalize_object (target);
+  g_assert_finalize_object (group);
+}
+
+static void
+test_signal_group_changing_target (void)
+{
+  SignalTarget *target1, *target2;
+  GSignalGroup *group = g_signal_group_new (signal_target_get_type ());
+  SignalTarget *readback;
+
+  connect_all_signals (group);
+  g_assert_null (g_signal_group_dup_target (group));
+
+  /* Set the target after connecting the signals */
+  target1 = g_object_new (signal_target_get_type (), NULL);
+  g_signal_group_set_target (group, target1);
+  readback = g_signal_group_dup_target (group);
+  g_assert_true (readback == target1);
+  g_object_unref (readback);
+
+  assert_signals (target1, group, TRUE);
+
+  /* Set the same target */
+  readback = g_signal_group_dup_target (group);
+  g_assert_true (readback == target1);
+  g_object_unref (readback);
+  g_signal_group_set_target (group, target1);
+
+  readback = g_signal_group_dup_target (group);
+  g_assert_true (readback == target1);
+  g_object_unref (readback);
+
+  assert_signals (target1, group, TRUE);
+
+  /* Set a new target when the current target is non-NULL */
+  target2 = g_object_new (signal_target_get_type (), NULL);
+  readback = g_signal_group_dup_target (group);
+  g_assert_true (readback == target1);
+  g_object_unref (readback);
+
+  g_signal_group_set_target (group, target2);
+  readback = g_signal_group_dup_target (group);
+  g_assert_true (readback == target2);
+  g_object_unref (readback);
+
+  assert_signals (target2, group, TRUE);
+
+  g_assert_finalize_object (target2);
+  g_assert_finalize_object (target1);
+  g_assert_finalize_object (group);
+}
+
+static void
+assert_blocking (SignalTarget *target,
+                 GSignalGroup *group,
+                 gint          count)
+{
+  gint i;
+
+  assert_signals (target, group, TRUE);
+
+  /* Assert that multiple blocks are effective */
+  for (i = 0; i < count; ++i)
+    {
+      g_signal_group_block (group);
+      assert_signals (target, group, FALSE);
+    }
+
+  /* Assert that the signal is not emitted after the first unblock */
+  for (i = 0; i < count; ++i)
+    {
+      assert_signals (target, group, FALSE);
+      g_signal_group_unblock (group);
+    }
+
+  assert_signals (target, group, TRUE);
+}
+
+static void
+test_signal_group_blocking (void)
+{
+  SignalTarget *target1, *target2, *readback;
+  GSignalGroup *group = g_signal_group_new (signal_target_get_type ());
+
+  /* Test blocking and unblocking null target */
+  g_signal_group_block (group);
+  g_signal_group_unblock (group);
+
+  connect_all_signals (group);
+  g_assert_null (g_signal_group_dup_target (group));
+
+  target1 = g_object_new (signal_target_get_type (), NULL);
+  g_signal_group_set_target (group, target1);
+  readback = g_signal_group_dup_target (group);
+  g_assert_true (readback == target1);
+  g_object_unref (readback);
+
+  assert_blocking (target1, group, 1);
+  assert_blocking (target1, group, 3);
+  assert_blocking (target1, group, 15);
+
+  /* Assert that blocking transfers across changing the target */
+  g_signal_group_block (group);
+  g_signal_group_block (group);
+
+  /* Set a new target when the current target is non-NULL */
+  target2 = g_object_new (signal_target_get_type (), NULL);
+  readback = g_signal_group_dup_target (group);
+  g_assert_true (readback == target1);
+  g_object_unref (readback);
+  g_signal_group_set_target (group, target2);
+  readback = g_signal_group_dup_target (group);
+  g_assert_true (readback == target2);
+  g_object_unref (readback);
+
+  assert_signals (target2, group, FALSE);
+  g_signal_group_unblock (group);
+  assert_signals (target2, group, FALSE);
+  g_signal_group_unblock (group);
+  assert_signals (target2, group, TRUE);
+
+  g_assert_finalize_object (target2);
+  g_assert_finalize_object (target1);
+  g_assert_finalize_object (group);
+}
+
+static void
+test_signal_group_weak_ref_target (void)
+{
+  SignalTarget *target = g_object_new (signal_target_get_type (), NULL);
+  GSignalGroup *group = g_signal_group_new (signal_target_get_type ());
+  SignalTarget *readback;
+
+  g_assert_null (g_signal_group_dup_target (group));
+  g_signal_group_set_target (group, target);
+  readback = g_signal_group_dup_target (group);
+  g_assert_true (readback == target);
+  g_object_unref (readback);
+
+  g_assert_finalize_object (target);
+  g_assert_null (g_signal_group_dup_target (group));
+  g_assert_finalize_object (group);
+}
+
+static void
+test_signal_group_connect_object (void)
+{
+  GObject *object = g_object_new (G_TYPE_OBJECT, NULL);
+  SignalTarget *target = g_object_new (signal_target_get_type (), NULL);
+  GSignalGroup *group = g_signal_group_new (signal_target_get_type ());
+  SignalTarget *readback;
+
+  /* We already do basic connect_object() tests in connect_signals(),
+   * this is only needed to test the specifics of connect_object()
+   */
+  g_signal_group_connect_object (group,
+                                 "the-signal",
+                                 G_CALLBACK (connect_object_cb),
+                                 object,
+                                 0);
+
+  g_assert_null (g_signal_group_dup_target (group));
+  g_signal_group_set_target (group, target);
+  readback = g_signal_group_dup_target (group);
+  g_assert_true (readback == target);
+  g_object_unref (readback);
+
+  g_assert_finalize_object (object);
+
+  /* This would cause a warning if the SignalGroup did not
+   * have a weakref on the object as it would try to connect again
+   */
+  g_signal_group_set_target (group, NULL);
+  g_assert_null (g_signal_group_dup_target (group));
+  g_signal_group_set_target (group, target);
+  readback = g_signal_group_dup_target (group);
+  g_assert_true (readback == target);
+  g_object_unref (readback);
+
+  g_assert_finalize_object (group);
+  g_assert_finalize_object (target);
+}
+
+static void
+test_signal_group_signal_parsing (void)
+{
+  g_test_trap_subprocess ("/GObject/SignalGroup/signal-parsing/subprocess", 0,
+                          G_TEST_SUBPROCESS_INHERIT_STDERR);
+  g_test_trap_assert_passed ();
+  g_test_trap_assert_stderr ("");
+}
+
+static void
+test_signal_group_signal_parsing_subprocess (void)
+{
+  GSignalGroup *group;
+
+  /* Check that the class has not been created and with it the
+   * signals registered. This will cause g_signal_parse_name()
+   * to fail unless GSignalGroup calls g_type_class_ref().
+   */
+  g_assert_null (g_type_class_peek (signal_target_get_type ()));
+
+  group = g_signal_group_new (signal_target_get_type ());
+  g_signal_group_connect (group,
+                          "the-signal",
+                          G_CALLBACK (connect_before_cb),
+                          NULL);
+
+  g_assert_finalize_object (group);
+}
+
+static void
+test_signal_group_properties (void)
+{
+  GSignalGroup *group;
+  SignalTarget *target, *other;
+  GType gtype;
+
+  group = g_signal_group_new (signal_target_get_type ());
+  g_object_get (group,
+                "target", &target,
+                "target-type", &gtype,
+                NULL);
+  g_assert_cmpint (gtype, ==, signal_target_get_type ());
+  g_assert_null (target);
+
+  target = g_object_new (signal_target_get_type (), NULL);
+  g_object_set (group, "target", target, NULL);
+  g_object_get (group, "target", &other, NULL);
+  g_assert_true (target == other);
+  g_object_unref (other);
+
+  g_assert_finalize_object (target);
+  g_assert_null (g_signal_group_dup_target (group));
+  g_assert_finalize_object (group);
+}
+
+G_DECLARE_INTERFACE (SignalThing, signal_thing, SIGNAL, THING, GObject)
+
+struct _SignalThingInterface
+{
+  GTypeInterface iface;
+  void (*changed) (SignalThing *thing);
+};
+
+G_DEFINE_INTERFACE (SignalThing, signal_thing, G_TYPE_OBJECT)
+
+static guint signal_thing_changed;
+
+static void
+signal_thing_default_init (SignalThingInterface *iface)
+{
+  signal_thing_changed =
+      g_signal_new ("changed",
+                    G_TYPE_FROM_INTERFACE (iface),
+                    G_SIGNAL_RUN_LAST,
+                    G_STRUCT_OFFSET (SignalThingInterface, changed),
+                    NULL, NULL, NULL,
+                    G_TYPE_NONE, 0);
+}
+
+G_GNUC_NORETURN static void
+thing_changed_cb (SignalThing *thing,
+                  gpointer     user_data G_GNUC_UNUSED)
+{
+  g_assert_not_reached ();
+}
+
+static void
+test_signal_group_interface (void)
+{
+  GSignalGroup *group;
+
+  group = g_signal_group_new (signal_thing_get_type ());
+  g_signal_group_connect (group,
+                          "changed",
+                          G_CALLBACK (thing_changed_cb),
+                          NULL);
+  g_assert_finalize_object (group);
+}
+
+gint
+main (gint   argc,
+      gchar *argv[])
+{
+  g_test_init (&argc, &argv, NULL);
+  g_test_add_func ("/GObject/SignalGroup/invalid", test_signal_group_invalid);
+  g_test_add_func ("/GObject/SignalGroup/simple", test_signal_group_simple);
+  g_test_add_func ("/GObject/SignalGroup/changing-target", test_signal_group_changing_target);
+  g_test_add_func ("/GObject/SignalGroup/blocking", test_signal_group_blocking);
+  g_test_add_func ("/GObject/SignalGroup/weak-ref-target", test_signal_group_weak_ref_target);
+  g_test_add_func ("/GObject/SignalGroup/connect-object", test_signal_group_connect_object);
+  g_test_add_func ("/GObject/SignalGroup/signal-parsing", test_signal_group_signal_parsing);
+  g_test_add_func ("/GObject/SignalGroup/signal-parsing/subprocess", test_signal_group_signal_parsing_subprocess);
+  g_test_add_func ("/GObject/SignalGroup/properties", test_signal_group_properties);
+  g_test_add_func ("/GObject/SignalGroup/interface", test_signal_group_interface);
+  return g_test_run ();
+}