use std::cell::RefCell;
use std::rc::Rc;

trait Upper {}
trait Lower: Upper {}

struct MyStruct {
}

impl Lower for MyStruct {
}

impl Upper for MyStruct {
}

fn main() {
    let object = Rc::new(RefCell::new(MyStruct {}));
    let lower = object as Rc<RefCell<dyn Lower>>;

    let upcast: Rc<RefCell<dyn Upper>> = lower;
}