error[E0328]: explicit impls for the `Unsize` trait are not permitted
  --> $DIR/E0328.rs:7:1
   |
LL | impl<T> Unsize<T> for MyType {}
   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^ impl of `Unsize` not allowed

error: aborting due to 1 previous error

For more information about this error, try `rustc --explain E0328`.