cast_to and virtual function confusing behavior

[chrisculver]

Summary: I ran into confusion implementing my own virtual function in a GDExtension class and overwritting it in GDScript. There may be a fix by properly binding the virtual method. For any solution an example could be added to the test/src/example.h

Minimal Test Program: Only showing the relevant part of the class, not the boilerplate for GDExtension.

// test.h
class Test : public Node 
{
    GDCLASS(Test, Node);
protected:
    static void _bind_methods();
public:
    virtual void update();
    void update_all_children();
};

// test.cpp
void Test::_bind_methods()
{
    // Abstract Methods
    ClassDB::bind_method("update", &Test::update);
    ClassDB::bind_method("update_all_children", &Test::update_all_children);
}
void Test::update()
{
    UtilityFunctions::print("Default update from node=",get_name());
}
void Test::update_all_children()
{
    for(size_t i=0; i<get_child_count(); ++i)
    {
        (Object::cast_to<Test>(get_child(i)))->update();
    }
}

Problem: If I overwrite the update method in GDScript, then future calls directly to update in GDScript call the correct update. The problem is when calling update_all_children in GDScript in which case all children will call the update you see defined in test.cpp.

Temporary Fix: Replace ->update() with `->call("update"). This produces the correct output for all children.

Solution: I think the ->update() syntax should call the overridden version in GDScript, not the cpp implementation. Perhaps this is how it works if using GDVIRTUAL0 or bind_virtual_method would. There isn't currenty an example for this, and I couldn't get it to compile on my own. Either way there isn't currently an example for defining and using your own virtual method.