error[E0308]: mismatched types
  --> $DIR/specialization-default-projection.rs:21:5
   |
LL | fn generic<T>() -> <T as Foo>::Assoc {
   |                    ----------------- expected `<T as Foo>::Assoc` because of return type
...
LL |     ()
   |     ^^ expected associated type, found ()
   |
   = note: expected associated type `<T as Foo>::Assoc`
                    found unit type `()`
   = note: consider constraining the associated type `<T as Foo>::Assoc` to `()` or calling a method that returns `<T as Foo>::Assoc`
   = note: for more information, visit https://doc.rust-lang.org/book/ch19-03-advanced-traits.html

error[E0308]: mismatched types
  --> $DIR/specialization-default-projection.rs:28:5
   |
LL | fn monomorphic() -> () {
   |                     -- expected `()` because of return type
...
LL |     generic::<()>()
   |     ^^^^^^^^^^^^^^^- help: try adding a semicolon: `;`
   |     |
   |     expected (), found associated type
   |
   = note:    expected unit type `()`
           found associated type `<() as Foo>::Assoc`
   = note: consider constraining the associated type `<() as Foo>::Assoc` to `()`
   = note: for more information, visit https://doc.rust-lang.org/book/ch19-03-advanced-traits.html

error: aborting due to 2 previous errors

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