error[E0307]: invalid `self` parameter type: T --> $DIR/issue-66312.rs:4:22 | LL | fn is_some(self: T); | ^ | = note: type of `self` must be `Self` or a type that dereferences to it = help: consider changing to `self`, `&self`, `&mut self`, `self: Box`, `self: Rc`, `self: Arc`, or `self: Pin

` (where P is one of the previous types except `Self`) error: aborting due to previous error For more information about this error, try `rustc --explain E0307`.