| error[E0596]: cannot borrow `v` as mutable, as it is not declared as mutable | |
| --> $DIR/issue-33819.rs:4:34 | |
| | | |
| LL | Some(ref v) => { let a = &mut v; }, | |
| | ^^^^^^ | |
| | | | |
| | cannot borrow as mutable | |
| | try removing `&mut` here | |
| error: aborting due to previous error | |
| For more information about this error, try `rustc --explain E0596`. |