1error[E0038]: the trait `Foo` cannot be made into an object 2 --> $DIR/arbitrary-self-types-not-object-safe.rs:33:32 3 | 4LL | fn foo(self: &Rc<Self>) -> usize; 5 | --------- help: consider changing method `foo`'s `self` parameter to be `&self`: `&Self` 6... 7LL | let x = Rc::new(5usize) as Rc<dyn Foo>; 8 | ^^^^^^^^^^^ `Foo` cannot be made into an object 9 | 10note: 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> 11 --> $DIR/arbitrary-self-types-not-object-safe.rs:8:18 12 | 13LL | trait Foo { 14 | --- this trait cannot be made into an object... 15LL | fn foo(self: &Rc<Self>) -> usize; 16 | ^^^^^^^^^ ...because method `foo`'s `self` parameter cannot be dispatched on 17 18error[E0038]: the trait `Foo` cannot be made into an object 19 --> $DIR/arbitrary-self-types-not-object-safe.rs:33:13 20 | 21LL | fn foo(self: &Rc<Self>) -> usize; 22 | --------- help: consider changing method `foo`'s `self` parameter to be `&self`: `&Self` 23... 24LL | let x = Rc::new(5usize) as Rc<dyn Foo>; 25 | ^^^^^^^^^^^^^^^ `Foo` cannot be made into an object 26 | 27note: 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> 28 --> $DIR/arbitrary-self-types-not-object-safe.rs:8:18 29 | 30LL | trait Foo { 31 | --- this trait cannot be made into an object... 32LL | fn foo(self: &Rc<Self>) -> usize; 33 | ^^^^^^^^^ ...because method `foo`'s `self` parameter cannot be dispatched on 34 = note: required because of the requirements on the impl of `CoerceUnsized<Rc<dyn Foo>>` for `Rc<usize>` 35 = note: required by cast to type `Rc<dyn Foo>` 36 37error: aborting due to 2 previous errors 38 39For more information about this error, try `rustc --explain E0038`. 40