get_rpc_config() can't get config of RPCs defined with @rpc

[dragonhunt02]

Tested versions

• Reproducible in v4.5.dev2

System information

Ubuntu 24.04 Godot v4.5.dev2

Issue description

get_rpc_config() returns empty dictionary if RPC functions are defined with @rpc annotation.
Configuring function with rpc_config() works as expected (dictionary is returned with methods)

- Test project
https://github.com/dragonhunt02/godot-rpc-get

Here are some rpc code sections I didn't check yet

godot/modules/gdscript/gdscript_parser.cpp

Lines 4995 to 5000 in 1696ab0

	bool GDScriptParser::rpc_annotation(AnnotationNode *p_annotation, Node *p_target, ClassNode *p_class) {
	ERR_FAIL_COND_V_MSG(p_target->type != Node::FUNCTION, false, vformat(R"("%s" annotation can only be applied to functions.)", p_annotation->name));
	FunctionNode *function = static_cast<FunctionNode *>(p_target);
	if (function->rpc_config.get_type() != Variant::NIL) {
	push_error(R"(RPC annotations can only be used once per function.)", p_annotation);

godot/modules/gdscript/gdscript_compiler.cpp

Lines 2902 to 2908 in 1696ab0

	case GDScriptParser::ClassNode::Member::FUNCTION: {
	const GDScriptParser::FunctionNode *function_n = member.function;
	Variant config = function_n->rpc_config;
	if (config.get_type() != Variant::NIL) {
	p_script->rpc_config[function_n->identifier->name] = config;
	}

Steps to reproduce

1. Write function with @rpc annotation
2. Call get_rpc_config() in class _ready method
3. Print return value

Minimal reproduction project (MRP)

https://github.com/dragonhunt02/godot-rpc-get/archive/refs/heads/main.zip

[dragonhunt02]

I ran more tests to investigate.

get_rpc_config() is exposed in GDScript on Node and GDScript instances.
These methods return rpc configs of a single Node OR GDScript instance.

godot/scene/main/node.cpp

Lines 852 to 853 in 25a3c27

	Variant Node::get_rpc_config() const {
	return data.rpc_config;

godot/modules/gdscript/gdscript.cpp

Lines 925 to 926 in 25a3c27

	Variant GDScript::get_rpc_config() const {
	return rpc_config;

This internal function parses rpc configs of a Node and its attached GDScript. It seems to be called before any execution of a rpc call to ensure all rpcs are cached and callable.

godot/modules/multiplayer/scene_rpc_interface.cpp

Lines 102 to 114 in 25a3c27

	const SceneRPCInterface::RPCConfigCache &SceneRPCInterface::_get_node_config(const Node *p_node) {
	const ObjectID oid = p_node->get_instance_id();
	if (rpc_cache.has(oid)) {
	return rpc_cache[oid];
	}
	RPCConfigCache cache;
	_parse_rpc_config(p_node->get_rpc_config(), true, cache);
	if (p_node->get_script_instance()) {
	_parse_rpc_config(p_node->get_script_instance()->get_rpc_config(), false, cache);
	}
	rpc_cache[oid] = cache;
	return rpc_cache[oid];
	}

When this internal function is called, it returns a correct rpc_config because it's fetching attached GDScript rpc configs too.

However Godot doesn't call this when using get_rpc_config() from GDScript but one of Node OR GDScript methods, so we get only one of the configs.

To fix this issue we could use/expose const SceneRPCInterface::RPCConfigCache &SceneRPCInterface::_get_node_config(const Node *p_node) as GDScript
get_rpc_config() or re-implement in class methods to return both Node and attached GDScript configs.