error[E0308]: mismatched types
  --> $DIR/box-future-wrong-output.rs:20:39
   |
LL |     let _: BoxFuture<'static, bool> = async {}.boxed();
   |            ------------------------   ^^^^^^^^^^^^^^^^ expected `bool`, found `()`
   |            |
   |            expected due to this
   |
   = note: expected struct `Pin<Box<(dyn Future<Output = bool> + Send + 'static)>>`
              found struct `Pin<Box<dyn Future<Output = ()> + Send>>`

error: aborting due to 1 previous error

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