error[E0720]: cannot resolve opaque type
  --> $DIR/recursive-in-exhaustiveness.rs:17:22
   |
LL | fn build<T>(x: T) -> impl Sized {
   |                      ^^^^^^^^^^

error[E0720]: cannot resolve opaque type
  --> $DIR/recursive-in-exhaustiveness.rs:27:23
   |
LL | fn build2<T>(x: T) -> impl Sized {
   |                       ^^^^^^^^^^

error[E0720]: cannot resolve opaque type
  --> $DIR/recursive-in-exhaustiveness.rs:37:23
   |
LL | fn build3<T>(x: T) -> impl Sized {
   |                       ^^^^^^^^^^

error: aborting due to 3 previous errors

For more information about this error, try `rustc --explain E0720`.