error[E0282]: type annotations needed
  --> $DIR/unbounded-associated-type.rs:15:5
   |
LL |     type A;
   |     ------- `<Self as T>::A` defined here
...
LL |     S(std::marker::PhantomData).foo();
   |     ^--------------------------------
   |     |
   |     this method call resolves to `<Self as T>::A`
   |     cannot infer type for type parameter `X`

error: aborting due to previous error

For more information about this error, try `rustc --explain E0282`.