warning: the feature `specialization` is incomplete and may not be safe to use and/or cause compiler crashes
  --> $DIR/specialization-default-types.rs:5:12
   |
LL | #![feature(specialization)]
   |            ^^^^^^^^^^^^^^
   |
   = note: see issue #31844 <https://github.com/rust-lang/rust/issues/31844> for more information
   = help: consider using `min_specialization` instead, which is more stable and complete
   = note: `#[warn(incomplete_features)]` on by default

error[E0308]: mismatched types
  --> $DIR/specialization-default-types.rs:15:9
   |
LL |     default type Output = Box<T>;
   |     ----------------------------- expected this associated type
LL |     default fn generate(self) -> Self::Output {
   |                                  ------------ expected `<T as Example>::Output` because of return type
LL |         Box::new(self)
   |         ^^^^^^^^^^^^^^ expected associated type, found struct `Box`
   |
   = note: expected associated type `<T as Example>::Output`
                       found struct `Box<T>`

error[E0308]: mismatched types
  --> $DIR/specialization-default-types.rs:25:5
   |
LL | fn trouble<T>(t: T) -> Box<T> {
   |                        ------ expected `Box<T>` because of return type
LL |     Example::generate(t)
   |     ^^^^^^^^^^^^^^^^^^^^ expected struct `Box`, found associated type
   |
   = note:       expected struct `Box<T>`
           found associated type `<T as Example>::Output`
   = help: consider constraining the associated type `<T as Example>::Output` to `Box<T>`
   = note: for more information, visit https://doc.rust-lang.org/book/ch19-03-advanced-traits.html

error: aborting due to 2 previous errors; 1 warning emitted

For more information about this error, try `rustc --explain E0308`.