Implicit binds in virtual calls cause borrow errors · Issue #338 · godot-rust/gdext (original) (raw)

Edit bromeon -- title was "Cannot addchild in a &mut self function if Self overrides onnotification"

#[derive(GodotClass)] #[class(init, base = Node)] pub struct Bar { #[base] base: Base, }

#[godot_api] impl NodeVirtual for Bar { fn ready(&mut self) { if Engine::singleton().is_editor_hint() { return; }

    let foo = Node::new_alloc();
    self.add_child(foo.share().upcast());
}

fn on_notification(&mut self, what: NodeNotification) {}

}

add_child will trigger a notification (https://docs.godotengine.org/en/stable/classes/class_node.html#class-node-constant-notification-child-order-changed), and that will in turn trigger a call to on_notification, which will try to get a mutable borrow of self. This causes a crash.

It seems like this is a big issue tbh because it basically makes self.add_child almost unusable whenever on_notification is overridden.

I'm not sure what a good solution to this is, but it's related to the common issue of calling a signal that will trigger on self.