#![feature(box_syntax)] struct Clam { x: Box, y: Box, } struct Fish { a: Box, } fn main() { let a: Clam = Clam{x: box 1, y: box 2}; let b: Clam = Clam{x: box 10, y: box 20}; let z: isize = a.x + b.y; //~^ ERROR binary operation `+` cannot be applied to type `std::boxed::Box` println!("{}", z); assert_eq!(z, 21); let forty: Fish = Fish{a: box 40}; let two: Fish = Fish{a: box 2}; let answer: isize = forty.a + two.a; //~^ ERROR binary operation `+` cannot be applied to type `std::boxed::Box` println!("{}", answer); assert_eq!(answer, 42); }