2 #![allow(non_camel_case_types)]
5 fn double(self) -> usize;
8 impl double for usize {
9 fn double(self) -> usize { self }
12 impl double for Box<usize> {
13 fn double(self) -> usize { *self * 2 }
17 let x: Box<_> = Box::new(3);
18 assert_eq!(x.double(), 6);