trait Y {}

struct X;

impl Drop for X {
    fn drop(&mut self) {
        println!("Dropping!");
    }
}

impl Y for X {}

fn take_ownership(x: Box<dyn Y>) {
    println!("About to drop!");
    std::mem::drop(x);
}

fn main() {
    let x: Box<dyn Y> = Box::new(X);
    take_ownership(x);
    println!("Should be dropped now");
}