| error[E0596]: cannot borrow `*y` as mutable, as it is behind a `&` reference | |
| --> $DIR/overloaded-index-without-indexmut.rs:14:5 | |
| | | |
| LL | y.push_str(""); | |
| | ^ `y` is a `&` reference, so the data it refers to cannot be borrowed as mutable | |
| error: aborting due to 1 previous error | |
| For more information about this error, try `rustc --explain E0596`. |