| error[E0596]: cannot borrow data in a `&` reference as mutable | |
| --> $DIR/index-mut-help-with-impl.rs:9:5 | |
| | | |
| LL | Index::index(&v, 1..2).make_ascii_uppercase(); | |
| | ^^^^^^^^^^^^^^^^^^^^^^ cannot borrow as mutable | |
| error: aborting due to 1 previous error | |
| For more information about this error, try `rustc --explain E0596`. |