error[E0046]: not all trait items implemented, missing: `foo_two`
  --> $DIR/specialization-trait-item-not-implemented.rs:18:1
   |
LL |     fn foo_two(&self) -> &'static str;
   |     ---------------------------------- `foo_two` from trait
...
LL | impl Foo for MyStruct {}
   | ^^^^^^^^^^^^^^^^^^^^^ missing `foo_two` in implementation

error: aborting due to previous error

For more information about this error, try `rustc --explain E0046`.