error[E0412]: cannot find type `Foo` in this scope
  --> $DIR/no-extern-crate-in-type.rs:5:22
   |
LL | type Output = Option<Foo>;
   |                      ^^^ not found in this scope
   |
help: consider importing this struct
   |
LL | use foo::Foo;
   |

error: aborting due to previous error

For more information about this error, try `rustc --explain E0412`.