Reimplement Resource._local_to_scene_setup & remove workaround

Reimplements the virtual method _setup_local_to_scene, lost in #51970, and renames it to `_local_to_scene_setup`.

Also removes the redundant `setup_local_to_scene_requested` signal.

core/io/resource.cpp

@@ -362,8 +362,10 @@ Node *Resource::get_local_scene() const {
 }
 
 void Resource::setup_local_to_scene() {
-	// Can't use GDVIRTUAL in Resource, so this will have to be done with a signal
-	emit_signal(SNAME("setup_local_to_scene_requested"));
+	if (get_script_instance()) {
+		Callable::CallError ce;
+		get_script_instance()->callp(SNAME("_local_to_scene_setup"), nullptr, 0, ce);
+	}
 }
 
 Node *(*Resource::_get_local_scene_func)() = nullptr;
@@ -431,7 +433,6 @@ void Resource::_bind_methods() {
 
 	ClassDB::bind_method(D_METHOD("duplicate", "subresources"), &Resource::duplicate, DEFVAL(false));
 	ADD_SIGNAL(MethodInfo("changed"));
-	ADD_SIGNAL(MethodInfo("setup_local_to_scene_requested"));
 
 	ADD_GROUP("Resource", "resource_");
 	ADD_PROPERTY(PropertyInfo(Variant::BOOL, "resource_local_to_scene"), "set_local_to_scene", "is_local_to_scene");
@@ -440,8 +441,10 @@ void Resource::_bind_methods() {
 
 	MethodInfo get_rid_bind("_get_rid");
 	get_rid_bind.return_val.type = Variant::RID;
-
 	::ClassDB::add_virtual_method(get_class_static(), get_rid_bind, true, Vector<String>(), true);
+
+	MethodInfo _local_to_scene_setup("_local_to_scene_setup");
+	::ClassDB::add_virtual_method(get_class_static(), _local_to_scene_setup, true, Vector<String>(), true);
 }
 
 Resource::Resource() :

doc/classes/Resource.xml

@@ -17,6 +17,21 @@
 			<description>
 			</description>
 		</method>
+		<method name="_local_to_scene_setup" qualifiers="virtual">
+			<return type="void" />
+			<description>
+				Override this method to customise the newly duplicated Resource created from [method PackedScene.instantiate], if the original's [member resource_local_to_scene] is set to [code]true[/code].
+				[b]Example:[/b] Assign a random value to [code]health[/code] for every duplicated Resource from an instantiated scene, excluding the original.
+				[codeblock]
+				extends Resource
+
+				var health = 0
+
+				func _local_to_scene_setup():
+				    health = randi_range(10, 40)
+				[/codeblock]
+			</description>
+		</method>
 		<method name="duplicate" qualifiers="const">
 			<return type="Resource" />
 			<param index="0" name="subresources" type="bool" default="false" />
@@ -84,9 +99,5 @@
 				[b]Note:[/b] This signal is not emitted automatically for custom resources, which means that you need to create a setter and emit the signal yourself.
 			</description>
 		</signal>
-		<signal name="setup_local_to_scene_requested">
-			<description>
-			</description>
-		</signal>
 	</signals>
 </class>

editor/project_converter_3_to_4.cpp

@@ -218,6 +218,7 @@ static const char *gdscript_function_renames[][2] = {
 	{ "_set_current", "set_current" }, // Camera2D
 	{ "_set_editor_description", "set_editor_description" }, // Node
 	{ "_set_playing", "set_playing" }, // AnimatedSprite3D
+	{ "_setup_local_to_scene", "_local_to_scene_setup" }, // Resource
 	{ "_toplevel_raise_self", "_top_level_raise_self" }, // CanvasItem
 	{ "_update_wrap_at", "_update_wrap_at_column" }, // TextEdit
 	{ "add_animation", "add_animation_library" }, // AnimationPlayer
@@ -664,6 +665,7 @@ static const char *csharp_function_renames[][2] = {
 	{ "_SetCurrent", "SetCurrent" }, // Camera2D
 	{ "_SetEditorDescription", "SetEditorDescription" }, // Node
 	{ "_SetPlaying", "SetPlaying" }, // AnimatedSprite3D
+	{ "_SetupLocalToScene", "_LocalToSceneSetup" }, // Resource
 	{ "_ToplevelRaiseSelf", "_TopLevelRaiseSelf" }, // CanvasItem
 	{ "_UpdateWrapAt", "_UpdateWrapAtColumn" }, // TextEdit
 	{ "AddAnimation", "AddAnimationLibrary" }, // AnimationPlayer