| //! Tests how we behave when the user attempts to mutate an immutable |
| //! binding that was introduced by either `ref` or `ref mut` |
| //! patterns. |
| //! |
| //! Such bindings cannot be made mutable via the mere addition of the |
| //! `mut` keyword, and thus we want to check that the compiler does not |
| //! suggest doing so. |
| |
| fn main() { |
| let (mut one_two, mut three_four) = ((1, 2), (3, 4)); |
| |
| // Bind via pattern: |
| // - `a` as immutable reference (`ref`) |
| // - `b` as mutable reference (`ref mut`) |
| let &mut (ref a, ref mut b) = &mut one_two; |
| |
| // Attempt to reassign immutable `ref`-bound variable |
| a = &three_four.0; |
| //~^ ERROR cannot assign twice to immutable variable `a` |
| |
| // Attempt to reassign mutable `ref mut`-bound variable |
| b = &mut three_four.1; |
| //~^ ERROR cannot assign twice to immutable variable `b` |
| } |
