src/test/ui/self/arbitrary-self-types-not-object-safe.object_safe_for_dispatch.stderr

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