error[E0053]: method `foo` has an incompatible type for trait
  --> $DIR/async-example-desugared-boxed-in-trait.rs:11:5
   |
LL |     async fn foo(&self) -> i32 {
   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^ expected `Pin<Box<dyn Future<Output = i32>>>`, found future
   |
note: type in trait
  --> $DIR/async-example-desugared-boxed-in-trait.rs:7:22
   |
LL |     fn foo(&self) -> Pin<Box<dyn Future<Output = i32> + '_>>;
   |                      ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
   = note: expected signature `fn(&_) -> Pin<Box<dyn Future<Output = i32>>>`
              found signature `fn(&_) -> impl Future<Output = i32>`

error: aborting due to 1 previous error

For more information about this error, try `rustc --explain E0053`.