4 #![allow(unused_variables)]
6 use std::io::{self, Write};
12 #[derive(Copy, Clone)]
18 impl Trait for Struct {
24 fn foo(mut a: Box<dyn Write>) {}
27 let a = Struct { x: 1, y: 2 };
28 let b: Box<dyn Trait> = Box::new(a);
30 let c: &dyn Trait = &a;
33 let out = io::stdout();