Overriding _input, _unhandled_input, or _unhandled_key_input crashes and produces system error

[valentinAlkan]

In GDExtensions 4.0, trying to override any of the input functions produces an error when input is detected. Code compiles, project runs normally, and everything is copacetic until input is detected. The following error is produced prior to crashing.

terminate called after throwing an instance of 'std::system_error'
  what():  Invalid argument

Function signature is as follows:

virtual void _unhandled_input(const Ref<InputEvent> &event) override{};

[nwroyer]

Looks like this might indicate a more general issue with overriding virtual functions in GDExtension classes - I ran into the same thing with _integrate_forces in #651. It might be worth merging these bug reports as this seems to be related or stemming from the same root cause.

[valentinAlkan]

A workaround is extending a GDExtension class with a GDSript. Overriding _input functions in GDScript and forwarding the events to another function in the GDExtension class that takes a variant seems to work.

GDExtensionBaseClassGD.gd

extends GDExtensionBaseClass
func _unhandled_input(event: InputEvent):
	_unhandled_input_forwarded(event)

GDExtensionBaseClass.cpp

void GDExtensionBaseClass::_unhandled_input_forwarded(Variant varEvent){
        //cast variant to input event
	InputEvent* event = cast_to<InputEvent>(varEvent);
	if (!event) return;
	UtilityFunctions::print("I am a forwarded input event");
	*do stuff*
    }
}
/////////////////////////////

void GDExtensionBaseClass::_bind_methods(){
        ClassDB::bind_method(D_METHOD("_input_forwarded"), &GDExtensionBaseClass::_unhandled_input_forwarded);
};

[Faless]

Fixed by #677