error[E0277]: the trait bound `(): std::ops::Fn<()>` is not satisfied --> $DIR/issue-22034.rs:18:16 | LL | &mut *(ptr as *mut Fn()) | ^^^ the trait `std::ops::Fn<()>` is not implemented for `()` | = note: required for the cast to the object type `dyn std::ops::Fn()` error: aborting due to previous error For more information about this error, try `rustc --explain E0277`.