error[E0599]: no method named `as_deref_mut` found for type `std::option::Option<{integer}>` in the current scope
  --> $DIR/option-as_deref_mut.rs:4:33
   |
LL |     let _result = &mut Some(42).as_deref_mut();
   |                                 ^^^^^^^^^^^^ method not found in `std::option::Option<{integer}>`
   |
   = note: the method `as_deref_mut` exists but the following trait bounds were not satisfied:
           `{integer} : std::ops::DerefMut`

error: aborting due to previous error

For more information about this error, try `rustc --explain E0599`.