//@ run-pass #![allow(non_camel_case_types)] trait clam { fn chowder(&self, y: A); } #[derive(Copy, Clone)] struct foo { x: A, } impl clam for foo { fn chowder(&self, _y: A) { } } fn foo(b: A) -> foo { foo { x: b } } fn f(x: Box>, a: A) { x.chowder(a); } pub fn main() { let c = foo(42); let d: Box> = Box::new(c) as Box>; f(d, c.x); }