error[E0033]: type `Box<(dyn MyTrait + 'static)>` cannot be dereferenced --> $DIR/issue-4972.rs:13:25 | LL | TraitWrapper::A(box ref map) => map, | ^^^^^^^^^^^ type `Box<(dyn MyTrait + 'static)>` cannot be dereferenced error: aborting due to 1 previous error For more information about this error, try `rustc --explain E0033`.