Nonexistent function 'rpc' in base 'Callable'

[AncRad]

Godot version

v4.1.dev3.official [a67d37f]

System information

Linux 5.4.0-135-generic

Issue description

I am trying to call Callable.rpc() and Callable.rpc_id(...) method but it doesn't work with some Callable.
If I call the .bind method and then call .rpc, I get the error "Invalid call. Nonexistent function 'rpc' in base 'Callable'.", execution aborts.

Issue is that we know for sure that the .rpc method in the Callable type is always present, and we would get a different error, but definitely not this one.

Steps to reproduce

Create an empty project, a new scene with Node at the root, and attach the following script to it:

extends Node

@rpc
func foo(value = null):
	print("foo(%s)" % value)

func _ready():
	
	rpc("foo") # ok
	
	rpc("foo", 123) # ok
	
	foo.rpc() # ok
	
	foo.rpc(123) # ok
	
	foo.bind(123).rpc() # error: "invalid call. Nonexistent function 'rpc' in base 'Callable'."
	
	foo.bindv([123]).rpc() # error: "invalid call. Nonexistent function 'rpc' in base 'Callable'."
	
	foo.bind(123).unbind(1).rpc() # error: "invalid call. Nonexistent function 'rpc' in base 'Callable'."
	
	foo.bindv([123]).unbind(1).rpc() # error: "invalid call. Nonexistent function 'rpc' in base 'Callable'."
	

Run the scene and observe the error. After an error, execution is interrupted, so comment out the found line to find the next error. Run the scene again.

See all available function values for these Callables. Except Callable.get_method() but that's a whole other issue.

	for callable in [foo, foo.bind(123), foo.bindv([123]), foo.bind(123).unbind(1), foo.bindv([123]).unbind(1)]:
		print("%6s ".repeat(11) % [
			callable,
			callable.get_bound_arguments(), callable.get_bound_arguments_count(), "callable.get_method()", callable.get_object(), callable.get_object_id(),
			callable.hash(), callable.is_custom(), callable.is_null(), callable.is_standard(), callable.is_valid()
		])

Minimal reproduction project

N / A

[akien-mga]

CC @KoBeWi

[dalexeev]

	foo.bind(123).unbind(1).rpc() # error: "invalid call. Nonexistent function 'rpc' in base 'Callable'."
	
	foo.bindv([123]).unbind(1).rpc() # error: "invalid call. Nonexistent function 'rpc' in base 'Callable'."

It has nothing to do with this bug, I just want to draw your attention to the fact that bind/unbind/call/rpc are applied from right to left. It's counterintuitive, but that's how things work. See #76141.

[AncRad]

It's counterintuitive, but that's how things work. See #76141.

Thank you. Now I understand it.

[AThousandShips]

The bind callables don't implement rpc unsure why, that's what's causing this

Will take a look at an approach for this

[KoBeWi]

Callable.bind() returns a Callable though.

[AThousandShips]

Yes but calling rpc on it calls the one on custom, which is not implemented for the bind versions

Got a working fix

[KoBeWi]

Seems like only GDScriptRPCCallable implements rpc() (likely for security reasons). It's the Callable created with @rpc annotation; if you use bind(), you get a different Callable.
Looks like a limitation, but if we were to implement rpc() for bind() and unbind(), it'd need to work only with the RPC callable.

[AThousandShips]

They will only do so, calling them elsewhere will cause the same error