error[E0038]: the trait `Trait` cannot be made into an object --> $DIR/feature-gate-dispatch-from-dyn-missing-impl.rs:32:25 | LL | fn ptr(self: Ptr<Self>); | --------- help: consider changing method `ptr`'s `self` parameter to be `&self`: `&Self` ... LL | Ptr(Box::new(4)) as Ptr<dyn Trait>; | ^^^^^^^^^^^^^^ `Trait` cannot be made into an object | note: for a trait to be "object safe" it needs to allow building a vtable to allow the call to be resolvable dynamically; for more information visit <https://doc.rust-lang.org/reference/items/traits.html#object-safety> --> $DIR/feature-gate-dispatch-from-dyn-missing-impl.rs:25:18 | LL | trait Trait { | ----- this trait cannot be made into an object... LL | fn ptr(self: Ptr<Self>); | ^^^^^^^^^ ...because method `ptr`'s `self` parameter cannot be dispatched on error[E0038]: the trait `Trait` cannot be made into an object --> $DIR/feature-gate-dispatch-from-dyn-missing-impl.rs:32:5 | LL | fn ptr(self: Ptr<Self>); | --------- help: consider changing method `ptr`'s `self` parameter to be `&self`: `&Self` ... LL | Ptr(Box::new(4)) as Ptr<dyn Trait>; | ^^^^^^^^^^^^^^^^ `Trait` cannot be made into an object | note: for a trait to be "object safe" it needs to allow building a vtable to allow the call to be resolvable dynamically; for more information visit <https://doc.rust-lang.org/reference/items/traits.html#object-safety> --> $DIR/feature-gate-dispatch-from-dyn-missing-impl.rs:25:18 | LL | trait Trait { | ----- this trait cannot be made into an object... LL | fn ptr(self: Ptr<Self>); | ^^^^^^^^^ ...because method `ptr`'s `self` parameter cannot be dispatched on note: required for `Ptr<{integer}>` to implement `CoerceUnsized<Ptr<dyn Trait>>` --> $DIR/feature-gate-dispatch-from-dyn-missing-impl.rs:20:40 | LL | impl<T: Unsize<U> + ?Sized, U: ?Sized> CoerceUnsized<Ptr<U>> for Ptr<T> {} | --------- ^^^^^^^^^^^^^^^^^^^^^ ^^^^^^ | | | unsatisfied trait bound introduced here = note: required by cast to type `Ptr<dyn Trait>` error: aborting due to 2 previous errors For more information about this error, try `rustc --explain E0038`.