From 4628736894203d4bb94e157ac011495da5bf8713 Mon Sep 17 00:00:00 2001
From: SaracenOne <SaracenOne@gmail.com>
Date: Sun, 30 Jan 2022 21:31:32 +0000
Subject: [PATCH] Update instances of scenes which have been reimported.

---
 doc/classes/Node.xml             |   3 +
 editor/editor_data.h             |   1 -
 editor/editor_node.cpp           | 478 ++++++++++++++++++++++++++++++-
 editor/editor_node.h             |  35 +++
 scene/main/node.cpp              |   1 +
 scene/main/node.h                |   1 +
 scene/resources/packed_scene.cpp |  19 ++
 scene/resources/packed_scene.h   |   2 +
 8 files changed, 538 insertions(+), 2 deletions(-)

diff --git a/doc/classes/Node.xml b/doc/classes/Node.xml
index 02fd6dae30f..7b27f16d827 100644
--- a/doc/classes/Node.xml
+++ b/doc/classes/Node.xml
@@ -909,6 +909,9 @@
 		<constant name="NOTIFICATION_ENABLED" value="29">
 			Notification received when the node is enabled again after being disabled. See [constant PROCESS_MODE_DISABLED].
 		</constant>
+		<constant name="NOTIFICATION_NODE_RECACHE_REQUESTED" value="30">
+			Notification received when other nodes in the tree may have been removed/replaced and node pointers may require re-caching.
+		</constant>
 		<constant name="NOTIFICATION_EDITOR_PRE_SAVE" value="9001">
 			Notification received right before the scene with the node is saved in the editor. This notification is only sent in the Godot editor and will not occur in exported projects.
 		</constant>
diff --git a/editor/editor_data.h b/editor/editor_data.h
index bce9dd345d5..5ef42da3c9c 100644
--- a/editor/editor_data.h
+++ b/editor/editor_data.h
@@ -203,7 +203,6 @@ public:
 	String get_scene_type(int p_idx) const;
 	void set_scene_path(int p_idx, const String &p_path);
 	Ref<Script> get_scene_root_script(int p_idx) const;
-	void set_edited_scene_version(uint64_t version, int p_scene_idx = -1);
 	void set_scene_modified_time(int p_idx, uint64_t p_time);
 	uint64_t get_scene_modified_time(int p_idx) const;
 	void clear_edited_scenes();
diff --git a/editor/editor_node.cpp b/editor/editor_node.cpp
index 62223b2445c..27283658234 100644
--- a/editor/editor_node.cpp
+++ b/editor/editor_node.cpp
@@ -58,6 +58,7 @@
 #include "scene/gui/tab_bar.h"
 #include "scene/gui/tab_container.h"
 #include "scene/main/window.h"
+#include "scene/property_utils.h"
 #include "scene/resources/packed_scene.h"
 #include "servers/display_server.h"
 #include "servers/navigation_server_3d.h"
@@ -997,6 +998,7 @@ void EditorNode::_resources_reimported(const Vector<String> &p_resources) {
 
 	for (const String &E : scenes) {
 		reload_scene(E);
+		reload_instances_with_path_in_edited_scenes(E);
 	}
 
 	scene_tabs->set_current_tab(current_tab);
@@ -3870,7 +3872,7 @@ Error EditorNode::load_scene(const String &p_scene, bool p_ignore_broken_deps, b
 		Ref<SceneState> state = sdata->get_state();
 		state->set_path(lpath);
 		new_scene->set_scene_inherited_state(state);
-		new_scene->set_scene_file_path(String());
+		new_scene->set_scene_file_path(lpath);
 	}
 
 	new_scene->set_scene_instance_state(Ref<SceneState>());
@@ -3904,6 +3906,134 @@ Error EditorNode::load_scene(const String &p_scene, bool p_ignore_broken_deps, b
 	return OK;
 }
 
+HashMap<StringName, Variant> EditorNode::get_modified_properties_for_node(Node *p_node) {
+	HashMap<StringName, Variant> modified_property_map;
+
+	List<PropertyInfo> pinfo;
+	p_node->get_property_list(&pinfo);
+	for (const PropertyInfo &E : pinfo) {
+		if (E.usage & PROPERTY_USAGE_STORAGE) {
+			bool is_valid_revert = false;
+			Variant revert_value = EditorPropertyRevert::get_property_revert_value(p_node, E.name, &is_valid_revert);
+			Variant current_value = p_node->get(E.name);
+			if (is_valid_revert) {
+				if (PropertyUtils::is_property_value_different(current_value, revert_value)) {
+					modified_property_map[E.name] = current_value;
+				}
+			}
+		}
+	}
+
+	return modified_property_map;
+}
+
+void EditorNode::update_diff_data_for_node(
+		Node *p_edited_scene,
+		Node *p_root,
+		Node *p_node,
+		HashMap<NodePath, ModificationNodeEntry> &p_modification_table,
+		List<AdditiveNodeEntry> &p_addition_list) {
+	bool node_part_of_subscene = p_node != p_edited_scene &&
+			p_edited_scene->get_scene_inherited_state().is_valid() &&
+			p_edited_scene->get_scene_inherited_state()->find_node_by_path(p_edited_scene->get_path_to(p_node)) >= 0;
+
+	// Loop through the owners until either we reach the root node or nullptr
+	Node *valid_node_owner = p_node->get_owner();
+	while (valid_node_owner) {
+		if (valid_node_owner == p_root) {
+			break;
+		}
+		valid_node_owner = valid_node_owner->get_owner();
+	}
+
+	if ((valid_node_owner == p_root && (p_root != p_edited_scene || !p_edited_scene->get_scene_file_path().is_empty())) || node_part_of_subscene || p_node == p_root) {
+		HashMap<StringName, Variant> modified_properties = get_modified_properties_for_node(p_node);
+
+		// Find all valid connections to other nodes.
+		List<Connection> connections_to;
+		p_node->get_all_signal_connections(&connections_to);
+
+		List<ConnectionWithNodePath> valid_connections_to;
+		for (const Connection &c : connections_to) {
+			Node *connection_target_node = Object::cast_to<Node>(c.callable.get_object());
+			if (connection_target_node) {
+				// TODO: add support for reinstating custom callables
+				if (!c.callable.is_custom()) {
+					ConnectionWithNodePath connection_to;
+					connection_to.connection = c;
+					connection_to.node_path = p_node->get_path_to(connection_target_node);
+					valid_connections_to.push_back(connection_to);
+				}
+			}
+		}
+
+		// Find all valid connections from other nodes.
+		List<Connection> connections_from;
+		p_node->get_signals_connected_to_this(&connections_from);
+
+		List<Connection> valid_connections_from;
+		for (const Connection &c : connections_from) {
+			Node *source_node = Object::cast_to<Node>(c.signal.get_object());
+
+			Node *valid_source_owner = nullptr;
+			if (source_node) {
+				valid_source_owner = source_node->get_owner();
+				while (valid_source_owner) {
+					if (valid_source_owner == p_root) {
+						break;
+					}
+					valid_source_owner = valid_source_owner->get_owner();
+				}
+			}
+
+			if (!source_node || valid_source_owner == nullptr) {
+				// TODO: add support for reinstating custom callables
+				if (!c.callable.is_custom()) {
+					valid_connections_from.push_back(c);
+				}
+			}
+		}
+
+		// Find all node groups.
+		List<Node::GroupInfo> groups;
+		p_node->get_groups(&groups);
+
+		if (!modified_properties.is_empty() || !valid_connections_to.is_empty() || !valid_connections_from.is_empty() || !groups.is_empty()) {
+			ModificationNodeEntry modification_node_entry;
+			modification_node_entry.property_table = modified_properties;
+			modification_node_entry.connections_to = valid_connections_to;
+			modification_node_entry.connections_from = valid_connections_from;
+			modification_node_entry.groups = groups;
+
+			p_modification_table[p_root->get_path_to(p_node)] = modification_node_entry;
+		}
+	} else {
+		AdditiveNodeEntry new_additive_node_entry;
+		new_additive_node_entry.node = p_node;
+		new_additive_node_entry.parent = p_root->get_path_to(p_node->get_parent());
+		new_additive_node_entry.owner = p_node->get_owner();
+		new_additive_node_entry.index = p_node->get_index();
+
+		Node2D *node_2d = Object::cast_to<Node2D>(p_node);
+		if (node_2d) {
+			new_additive_node_entry.transform_2d = node_2d->get_relative_transform_to_parent(node_2d->get_parent());
+		}
+		Node3D *node_3d = Object::cast_to<Node3D>(p_node);
+		if (node_3d) {
+			new_additive_node_entry.transform_3d = node_3d->get_relative_transform(node_3d->get_parent());
+		}
+		p_addition_list.push_back(new_additive_node_entry);
+
+		return;
+	}
+
+	for (int i = 0; i < p_node->get_child_count(); i++) {
+		Node *child = p_node->get_child(i);
+		update_diff_data_for_node(p_edited_scene, p_root, child, p_modification_table, p_addition_list);
+	}
+}
+//
+
 void EditorNode::open_request(const String &p_path) {
 	if (!opening_prev) {
 		List<String>::Element *prev_scene_item = previous_scenes.find(p_path);
@@ -5760,6 +5890,352 @@ void EditorNode::reload_scene(const String &p_path) {
 	scene_tabs->set_current_tab(current_tab);
 }
 
+void EditorNode::find_all_instances_inheriting_path_in_node(Node *p_root, Node *p_node, const String &p_instance_path, List<Node *> &p_instance_list) {
+	String scene_file_path = p_node->get_scene_file_path();
+
+	// This is going to get messy...
+	if (p_node->get_scene_file_path() == p_instance_path) {
+		p_instance_list.push_back(p_node);
+	} else {
+		Node *current_node = p_node;
+
+		Ref<SceneState> inherited_state = current_node->get_scene_inherited_state();
+		while (inherited_state.is_valid()) {
+			String inherited_path = inherited_state->get_path();
+			if (inherited_path == p_instance_path) {
+				p_instance_list.push_back(p_node);
+				break;
+			}
+
+			inherited_state = inherited_state->get_base_scene_state();
+		}
+	}
+
+	for (int i = 0; i < p_node->get_child_count(); i++) {
+		Node *child = p_node->get_child(i);
+		find_all_instances_inheriting_path_in_node(p_root, child, p_instance_path, p_instance_list);
+	}
+}
+
+void EditorNode::reload_instances_with_path_in_edited_scenes(const String &p_instance_path) {
+	int original_edited_scene_idx = editor_data.get_edited_scene();
+	HashMap<int, List<Node *>> edited_scene_map;
+
+	// Walk through each opened scene to get a global list of all instances which match
+	// the current reimported scenes.
+	for (int i = 0; i < editor_data.get_edited_scene_count(); i++) {
+		if (editor_data.get_scene_path(i) != p_instance_path) {
+			Node *edited_scene_root = editor_data.get_edited_scene_root(i);
+
+			if (edited_scene_root) {
+				List<Node *> valid_nodes;
+				find_all_instances_inheriting_path_in_node(edited_scene_root, edited_scene_root, p_instance_path, valid_nodes);
+				if (valid_nodes.size() > 0) {
+					edited_scene_map[i] = valid_nodes;
+				}
+			}
+		}
+	}
+
+	if (edited_scene_map.size() > 0) {
+		// Reload the new instance.
+		Error err;
+		Ref<PackedScene> instance_scene_packed_scene = ResourceLoader::load(p_instance_path, "", ResourceFormatLoader::CACHE_MODE_IGNORE, &err);
+		instance_scene_packed_scene->set_path(p_instance_path, true);
+
+		ERR_FAIL_COND(err != OK);
+		ERR_FAIL_COND(instance_scene_packed_scene.is_null());
+
+		HashMap<String, Ref<PackedScene>> local_scene_cache;
+		local_scene_cache[p_instance_path] = instance_scene_packed_scene;
+
+		for (const KeyValue<int, List<Node *>> &edited_scene_map_elem : edited_scene_map) {
+			// Set the current scene.
+			int current_scene_idx = edited_scene_map_elem.key;
+			editor_data.set_edited_scene(current_scene_idx);
+			Node *current_edited_scene = editor_data.get_edited_scene_root(current_scene_idx);
+
+			// Clear the history for this tab (should we allow history to be retained?).
+			EditorUndoRedoManager::get_singleton()->clear_history();
+
+			// Update the version
+			editor_data.is_scene_changed(current_scene_idx);
+
+			for (Node *original_node : edited_scene_map_elem.value) {
+				// Walk the tree for the current node and extract relevant diff data, storing it in the modification table.
+				// For additional nodes which are part of the current scene, they get added to the addition table.
+				HashMap<NodePath, ModificationNodeEntry> modification_table;
+				List<AdditiveNodeEntry> addition_list;
+				update_diff_data_for_node(current_edited_scene, original_node, original_node, modification_table, addition_list);
+
+				// Disconnect all relevant connections, all connections from and persistent connections to.
+				for (const KeyValue<NodePath, ModificationNodeEntry> &modification_table_entry : modification_table) {
+					for (Connection conn : modification_table_entry.value.connections_from) {
+						conn.signal.get_object()->disconnect(conn.signal.get_name(), conn.callable);
+					}
+					for (ConnectionWithNodePath cwnp : modification_table_entry.value.connections_to) {
+						Connection conn = cwnp.connection;
+						if (conn.flags & CONNECT_PERSIST) {
+							conn.signal.get_object()->disconnect(conn.signal.get_name(), conn.callable);
+						}
+					}
+				}
+
+				// Store all the paths for any selected nodes which are ancestors of the node we're replacing.
+				List<NodePath> selected_node_paths;
+				for (Node *selected_node : editor_selection->get_selected_node_list()) {
+					if (selected_node == original_node || original_node->is_ancestor_of(selected_node)) {
+						selected_node_paths.push_back(original_node->get_path_to(selected_node));
+						editor_selection->remove_node(selected_node);
+					}
+				}
+
+				// Remove all nodes which were added as additional elements (they will be restored later).
+				for (AdditiveNodeEntry additive_node_entry : addition_list) {
+					Node *addition_node = additive_node_entry.node;
+					addition_node->get_parent()->remove_child(addition_node);
+				}
+
+				// Clear ownership of the nodes (kind of hack to workaround an issue with
+				// replace_by when called on nodes in other tabs).
+				List<Node *> nodes_owned_by_original_node;
+				original_node->get_owned_by(original_node, &nodes_owned_by_original_node);
+				for (Node *owned_node : nodes_owned_by_original_node) {
+					owned_node->set_owner(nullptr);
+				}
+
+				// Delete all the remaining node children.
+				while (original_node->get_child_count()) {
+					Node *child = original_node->get_child(0);
+
+					original_node->remove_child(child);
+					child->queue_free();
+				}
+
+				// Reset the editable instance state.
+				bool is_editable = true;
+				Node *owner = original_node->get_owner();
+				if (owner) {
+					is_editable = owner->is_editable_instance(original_node);
+				}
+
+				// Load a replacement scene for the node.
+				Ref<PackedScene> current_packed_scene;
+				if (original_node->get_scene_file_path() == p_instance_path) {
+					// If the node file name directly matches the scene we're replacing,
+					// just load it since we already cached it.
+					current_packed_scene = instance_scene_packed_scene;
+				} else {
+					// Otherwise, check the inheritance chain, reloading and caching any scenes
+					// we require along the way.
+					List<String> required_load_paths;
+					String scene_path = original_node->get_scene_file_path();
+					// Do we need to check if the paths are empty?
+					if (!scene_path.is_empty()) {
+						required_load_paths.push_front(scene_path);
+					}
+					Ref<SceneState> inherited_state = original_node->get_scene_inherited_state();
+					while (inherited_state.is_valid()) {
+						String inherited_path = inherited_state->get_path();
+						// Do we need to check if the paths are empty?
+						if (!inherited_path.is_empty()) {
+							required_load_paths.push_front(inherited_path);
+						}
+						inherited_state = inherited_state->get_base_scene_state();
+					}
+
+					// Ensure the inheritance chain is loaded in the correct order so that cache can
+					// be properly updated.
+					for (String path : required_load_paths) {
+						if (!local_scene_cache.find(path)) {
+							current_packed_scene = ResourceLoader::load(path, "", ResourceFormatLoader::CACHE_MODE_IGNORE, &err);
+							current_packed_scene->set_path(path, true);
+							local_scene_cache[path] = current_packed_scene;
+						} else {
+							current_packed_scene = local_scene_cache[path];
+						}
+					}
+				}
+
+				ERR_FAIL_COND(current_packed_scene.is_null());
+
+				// Instantiate the node.
+				Node *instantiated_node = nullptr;
+				if (current_packed_scene.is_valid()) {
+					instantiated_node = current_packed_scene->instantiate(PackedScene::GEN_EDIT_STATE_INSTANCE);
+				}
+
+				ERR_FAIL_COND(!instantiated_node);
+
+				bool original_node_is_displayed_folded = original_node->is_displayed_folded();
+				bool original_node_scene_instance_load_placeholder = original_node->get_scene_instance_load_placeholder();
+
+				// Update the name to match
+				instantiated_node->set_name(original_node->get_name());
+
+				// Is this replacing the edited root node?
+				String original_node_file_path = original_node->get_scene_file_path();
+
+				if (current_edited_scene == original_node) {
+					instantiated_node->set_scene_instance_state(original_node->get_scene_instance_state());
+					// Fix unsaved inherited scene
+					if (original_node_file_path.is_empty()) {
+						Ref<SceneState> state = current_packed_scene->get_state();
+						state->set_path(current_packed_scene->get_path());
+						instantiated_node->set_scene_inherited_state(state);
+					}
+					editor_data.set_edited_scene_root(instantiated_node);
+					current_edited_scene = instantiated_node;
+
+					if (original_node->is_inside_tree()) {
+						SceneTreeDock::get_singleton()->set_edited_scene(current_edited_scene);
+						original_node->get_tree()->set_edited_scene_root(instantiated_node);
+					}
+				}
+
+				// Replace the original node with the instantiated version.
+				original_node->replace_by(instantiated_node, false);
+
+				// Mark the old node for deletion.
+				original_node->queue_free();
+
+				// Restore the folded and placeholder state from the original node.
+				instantiated_node->set_display_folded(original_node_is_displayed_folded);
+				instantiated_node->set_scene_instance_load_placeholder(original_node_scene_instance_load_placeholder);
+
+				if (owner) {
+					Ref<SceneState> ss_inst = owner->get_scene_instance_state();
+					if (ss_inst.is_valid()) {
+						ss_inst->update_instance_resource(p_instance_path, current_packed_scene);
+					}
+
+					owner->set_editable_instance(instantiated_node, is_editable);
+				}
+
+				// Attempt to re-add all the additional nodes.
+				for (AdditiveNodeEntry additive_node_entry : addition_list) {
+					Node *parent_node = instantiated_node->get_node_or_null(additive_node_entry.parent);
+
+					if (!parent_node) {
+						parent_node = current_edited_scene;
+					}
+
+					parent_node->add_child(additive_node_entry.node);
+					parent_node->move_child(additive_node_entry.node, additive_node_entry.index);
+					// If the additive node's owner was the node which got replaced, update it.
+					if (additive_node_entry.owner == original_node) {
+						additive_node_entry.owner = instantiated_node;
+					}
+
+					additive_node_entry.node->set_owner(additive_node_entry.owner);
+
+					// If the parent node was lost, attempt to restore the original global transform.
+					{
+						Node2D *node_2d = Object::cast_to<Node2D>(additive_node_entry.node);
+						if (node_2d) {
+							node_2d->set_transform(additive_node_entry.transform_2d);
+						}
+
+						Node3D *node_3d = Object::cast_to<Node3D>(additive_node_entry.node);
+						if (node_3d) {
+							node_3d->set_transform(additive_node_entry.transform_3d);
+						}
+					}
+				}
+
+				// Restore the selection.
+				if (selected_node_paths.size()) {
+					for (NodePath selected_node_path : selected_node_paths) {
+						Node *selected_node = instantiated_node->get_node_or_null(selected_node_path);
+						if (selected_node) {
+							editor_selection->add_node(selected_node);
+						}
+					}
+					editor_selection->update();
+				}
+
+				// Attempt to restore the modified properties and signals for the instantitated node and all its owned children.
+				for (KeyValue<NodePath, ModificationNodeEntry> &E : modification_table) {
+					NodePath new_current_path = E.key;
+					Node *modifiable_node = instantiated_node->get_node_or_null(new_current_path);
+
+					if (modifiable_node) {
+						// Get properties for this node.
+						List<PropertyInfo> pinfo;
+						modifiable_node->get_property_list(&pinfo);
+
+						// Get names of all valid property names (TODO: make this more efficent).
+						List<String> property_names;
+						for (const PropertyInfo &E2 : pinfo) {
+							if (E2.usage & PROPERTY_USAGE_STORAGE) {
+								property_names.push_back(E2.name);
+							}
+						}
+
+						// Restore the modified properties for this node.
+						for (const KeyValue<StringName, Variant> &E2 : E.value.property_table) {
+							if (property_names.find(E2.key)) {
+								modifiable_node->set(E2.key, E2.value);
+							}
+						}
+						// Restore the connections to other nodes.
+						for (const ConnectionWithNodePath &E2 : E.value.connections_to) {
+							Connection conn = E2.connection;
+
+							// Get the node the callable is targetting.
+							Node *target_node = cast_to<Node>(conn.callable.get_object());
+
+							// If the callable object no longer exists or is marked for deletion,
+							// attempt to reaccquire the closest match by using the node path
+							// we saved earlier.
+							if (!target_node || !target_node->is_queued_for_deletion()) {
+								target_node = modifiable_node->get_node_or_null(E2.node_path);
+							}
+
+							if (target_node) {
+								// Reconstruct the callable.
+								Callable new_callable = Callable(target_node, conn.callable.get_method());
+
+								if (!modifiable_node->is_connected(conn.signal.get_name(), new_callable)) {
+									ERR_FAIL_COND(modifiable_node->connect(conn.signal.get_name(), new_callable, conn.flags) != OK);
+								}
+							}
+						}
+
+						// Restore the connections from other nodes.
+						for (const Connection &E2 : E.value.connections_from) {
+							Connection conn = E2;
+
+							bool valid = modifiable_node->has_method(conn.callable.get_method()) || Ref<Script>(modifiable_node->get_script()).is_null() || Ref<Script>(modifiable_node->get_script())->has_method(conn.callable.get_method());
+							ERR_CONTINUE_MSG(!valid, vformat("Attempt to connect signal '%s.%s' to nonexistent method '%s.%s'.", conn.signal.get_object()->get_class(), conn.signal.get_name(), conn.callable.get_object()->get_class(), conn.callable.get_method()));
+
+							// Get the object which the signal is connected from.
+							Object *source_object = conn.signal.get_object();
+
+							if (source_object) {
+								ERR_FAIL_COND(source_object->connect(conn.signal.get_name(), Callable(modifiable_node, conn.callable.get_method()), conn.flags) != OK);
+							}
+						}
+
+						// Re-add the groups.
+						for (const Node::GroupInfo &E2 : E.value.groups) {
+							modifiable_node->add_to_group(E2.name, E2.persistent);
+						}
+					}
+				}
+			}
+			// Cleanup the history of the changes.
+			editor_history.cleanup_history();
+
+			current_edited_scene->propagate_notification(NOTIFICATION_NODE_RECACHE_REQUESTED);
+		}
+		edited_scene_map.clear();
+	}
+	editor_data.set_edited_scene(original_edited_scene_idx);
+
+	_edit_current();
+}
+
 int EditorNode::plugin_init_callback_count = 0;
 
 void EditorNode::add_plugin_init_callback(EditorPluginInitializeCallback p_callback) {
diff --git a/editor/editor_node.h b/editor/editor_node.h
index fb2544c141a..163a056c8c9 100644
--- a/editor/editor_node.h
+++ b/editor/editor_node.h
@@ -86,6 +86,7 @@ class ImportDock;
 class LinkButton;
 class MenuBar;
 class MenuButton;
+class Node2D;
 class NodeDock;
 class OptionButton;
 class OrphanResourcesDialog;
@@ -820,6 +821,37 @@ public:
 	Error load_scene(const String &p_scene, bool p_ignore_broken_deps = false, bool p_set_inherited = false, bool p_clear_errors = true, bool p_force_open_imported = false, bool p_silent_change_tab = false);
 	Error load_resource(const String &p_resource, bool p_ignore_broken_deps = false);
 
+	HashMap<StringName, Variant> get_modified_properties_for_node(Node *p_node);
+
+	struct AdditiveNodeEntry {
+		Node *node = nullptr;
+		NodePath parent = NodePath();
+		Node *owner = nullptr;
+		int index = 0;
+		// Used if the original parent node is lost
+		Transform2D transform_2d;
+		Transform3D transform_3d;
+	};
+
+	struct ConnectionWithNodePath {
+		Connection connection;
+		NodePath node_path;
+	};
+
+	struct ModificationNodeEntry {
+		HashMap<StringName, Variant> property_table;
+		List<ConnectionWithNodePath> connections_to;
+		List<Connection> connections_from;
+		List<Node::GroupInfo> groups;
+	};
+
+	void update_diff_data_for_node(
+			Node *p_edited_scene,
+			Node *p_root,
+			Node *p_node,
+			HashMap<NodePath, ModificationNodeEntry> &p_modification_table,
+			List<AdditiveNodeEntry> &p_addition_list);
+
 	bool is_scene_open(const String &p_path);
 
 	void set_current_scene(int p_idx);
@@ -872,6 +904,9 @@ public:
 
 	void reload_scene(const String &p_path);
 
+	void find_all_instances_inheriting_path_in_node(Node *p_root, Node *p_node, const String &p_instance_path, List<Node *> &p_instance_list);
+	void reload_instances_with_path_in_edited_scenes(const String &p_path);
+
 	bool is_exiting() const { return exiting; }
 
 	Button *get_pause_button() { return pause_button; }
diff --git a/scene/main/node.cpp b/scene/main/node.cpp
index eb57ccfef11..0e4abf74210 100644
--- a/scene/main/node.cpp
+++ b/scene/main/node.cpp
@@ -2943,6 +2943,7 @@ void Node::_bind_methods() {
 	BIND_CONSTANT(NOTIFICATION_POST_ENTER_TREE);
 	BIND_CONSTANT(NOTIFICATION_DISABLED);
 	BIND_CONSTANT(NOTIFICATION_ENABLED);
+	BIND_CONSTANT(NOTIFICATION_NODE_RECACHE_REQUESTED);
 
 	BIND_CONSTANT(NOTIFICATION_EDITOR_PRE_SAVE);
 	BIND_CONSTANT(NOTIFICATION_EDITOR_POST_SAVE);
diff --git a/scene/main/node.h b/scene/main/node.h
index dbdcca6170b..493578bc5be 100644
--- a/scene/main/node.h
+++ b/scene/main/node.h
@@ -270,6 +270,7 @@ public:
 		NOTIFICATION_POST_ENTER_TREE = 27,
 		NOTIFICATION_DISABLED = 28,
 		NOTIFICATION_ENABLED = 29,
+		NOTIFICATION_NODE_RECACHE_REQUESTED = 30,
 		//keep these linked to node
 
 		NOTIFICATION_WM_MOUSE_ENTER = 1002,
diff --git a/scene/resources/packed_scene.cpp b/scene/resources/packed_scene.cpp
index 514e7eb2605..b0c2f1d7f5b 100644
--- a/scene/resources/packed_scene.cpp
+++ b/scene/resources/packed_scene.cpp
@@ -1047,6 +1047,25 @@ Ref<SceneState> SceneState::get_base_scene_state() const {
 	return Ref<SceneState>();
 }
 
+void SceneState::update_instance_resource(String p_path, Ref<PackedScene> p_packed_scene) {
+	ERR_FAIL_COND(p_packed_scene.is_null());
+
+	for (const NodeData &nd : nodes) {
+		if (nd.instance >= 0) {
+			if (!(nd.instance & FLAG_INSTANCE_IS_PLACEHOLDER)) {
+				int instance_id = nd.instance & FLAG_MASK;
+				Ref<PackedScene> original_packed_scene = variants[instance_id];
+				if (original_packed_scene.is_valid()) {
+					if (original_packed_scene->get_path() == p_path) {
+						variants.remove_at(instance_id);
+						variants.insert(instance_id, p_packed_scene);
+					}
+				}
+			}
+		}
+	}
+}
+
 int SceneState::find_node_by_path(const NodePath &p_node) const {
 	ERR_FAIL_COND_V_MSG(node_path_cache.size() == 0, -1, "This operation requires the node cache to have been built.");
 
diff --git a/scene/resources/packed_scene.h b/scene/resources/packed_scene.h
index ef7363dd441..5c53ffdb456 100644
--- a/scene/resources/packed_scene.h
+++ b/scene/resources/packed_scene.h
@@ -150,6 +150,8 @@ public:
 
 	Ref<SceneState> get_base_scene_state() const;
 
+	void update_instance_resource(String p_path, Ref<PackedScene> p_packed_scene);
+
 	//unbuild API
 
 	int get_node_count() const;