error[E0038]: the trait `Trait` cannot be made into an object
  --> $DIR/E0038.rs:5:16
   |
LL | trait Trait {
   |       ----- this trait cannot be made into an object...
LL |     fn foo(&self) -> Self;
   |                      ---- ...because method `foo` references the `Self` type in its return type
...
LL | fn call_foo(x: Box<dyn Trait>) {
   |                ^^^^^^^^^^^^^^ the trait `Trait` cannot be made into an object
   |
   = help: consider moving `foo` to another trait

error: aborting due to previous error

For more information about this error, try `rustc --explain E0038`.