fn foo<'a, 'b>(x: &'a mut i32, y: &'b mut i32) -> &'b mut i32 { y }

fn main() {
  `[let mut x = 1;]`
  `[let mut y = 2;]`
  `[let z = foo(&mut x, &mut y);]`
  *z += 1;
  `[x;]`
}