error[E0384]: cannot assign twice to immutable variable `a`
  --> $DIR/pattern-ref-bindings-reassignment.rs:18:5
   |
LL |     let &mut (ref a, ref mut b) = &mut one_two;
   |               ----- first assignment to `a`
...
LL |     a = &three_four.0;
   |     ^^^^^^^^^^^^^^^^^ cannot assign twice to immutable variable

error[E0384]: cannot assign twice to immutable variable `b`
  --> $DIR/pattern-ref-bindings-reassignment.rs:22:5
   |
LL |     let &mut (ref a, ref mut b) = &mut one_two;
   |                      --------- first assignment to `b`
...
LL |     b = &mut three_four.1;
   |     ^^^^^^^^^^^^^^^^^^^^^ cannot assign twice to immutable variable

error: aborting due to 2 previous errors

For more information about this error, try `rustc --explain E0384`.