1 // Tests how we behave when the user attempts to mutate an immutable
2 // binding that was introduced by either `ref` or `ref mut`
5 // Such bindings cannot be made mutable via the mere addition of the
6 // `mut` keyword, and thus we want to check that the compiler does not
10 let (mut one_two, mut three_four) = ((1, 2), (3, 4));
11 let &mut (ref a, ref mut b) = &mut one_two;
13 //~^ ERROR cannot assign twice to immutable variable `a` [E0384]
14 b = &mut three_four.1;
15 //~^ ERROR cannot assign twice to immutable variable `b` [E0384]