error[E0308]: `if` and `else` have incompatible types
  --> $DIR/opaque-type-error.rs:20:9
   |
LL |   fn thing_one() -> impl Future<Output = Result<(), ()>> {
   |                     ------------------------------------ the expected future
...
LL |   fn thing_two() -> impl Future<Output = Result<(), ()>> {
   |                     ------------------------------------ the found future
...
LL | /     if true {
LL | |         thing_one()
   | |         ----------- expected because of this
LL | |     } else {
LL | |         thing_two()
   | |         ^^^^^^^^^^^ expected future, found a different future
LL | |     }.await
   | |_____- `if` and `else` have incompatible types
   |
   = note: distinct uses of `impl Trait` result in different opaque types
help: consider `await`ing on both `Future`s
   |
LL ~         thing_one().await
LL |     } else {
LL ~         thing_two().await
   |

error: aborting due to previous error

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