error[E0117]: only traits defined in the current crate can be implemented for arbitrary types
  --> $DIR/coherence.rs:14:1
   |
LL | impl<T> foreign_crate::ForeignTrait for AliasOfForeignType<T> {}
   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^---------------------
   | |                                       |
   | |                                       type alias impl trait is treated as if it were foreign, because its hidden type could be from a foreign crate
   | impl doesn't use only types from inside the current crate
   |
   = note: define and implement a trait or new type instead

error: aborting due to previous error

For more information about this error, try `rustc --explain E0117`.