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