error[E0599]: the method `as_deref_mut` exists for enum `Option<{integer}>`, but its trait bounds were not satisfied --> $DIR/option-as_deref_mut.rs:2:33 | LL | let _result = &mut Some(42).as_deref_mut(); | ^^^^^^^^^^^^ | = note: the following trait bounds were not satisfied: `{integer}: Deref` error: aborting due to previous error For more information about this error, try `rustc --explain E0599`.