Fun with order of evaluation

r.rs

fn main() {
  let mut q = Q(0);

  *{ println!("left" ); &mut q.0 } +=         { print!  ("right "); 1 };    // right left
   { print!  ("left "); &mut q.0 }.add_assign({ println!("right"); 1 });    // left right

  *{ print!  ("left "); &mut q   } +=         { println!("right"); Q(1) };  // left right
   { print!  ("left "); &mut q   }.add_assign({ println!("right"); Q(1) }); // left right

  ltr(0usize); // left right, even though += is used with usize: the evaluation order is determined before monomorphization
  fn ltr<T: AddAssign + Copy>(mut x: T) {
    let y = x;
    *{ print!  ("left "); &mut x } += { println!("right"); y }
  }
}

#[derive(Clone, Copy)]
struct Q(usize);

use std::ops::{Add, AddAssign};

impl Add for Q {
    type Output = Q;
    fn add(self, r: Self) -> Self {
       Q(self.0 + r.0)
    }
}

impl AddAssign for Q {
    fn add_assign(&mut self, r: Self) {
      *self = *self + r
    }
}