error: implementation of `FnOnce` is not general enough
  --> $DIR/higher-ranked-auto-trait-17.rs:12:5
   |
LL | /     async move {
LL | |         let iter = Adaptor::new(a.iter().map(|_: &()| {}));
LL | |         std::future::pending::<()>().await;
LL | |         drop(iter);
LL | |     }
   | |_____^ implementation of `FnOnce` is not general enough
   |
   = note: closure with signature `fn(&'0 ())` must implement `FnOnce<(&'1 (),)>`, for any two lifetimes `'0` and `'1`...
   = note: ...but it actually implements `FnOnce<(&(),)>`

error: implementation of `FnOnce` is not general enough
  --> $DIR/higher-ranked-auto-trait-17.rs:12:5
   |
LL | /     async move {
LL | |         let iter = Adaptor::new(a.iter().map(|_: &()| {}));
LL | |         std::future::pending::<()>().await;
LL | |         drop(iter);
LL | |     }
   | |_____^ implementation of `FnOnce` is not general enough
   |
   = note: closure with signature `fn(&'0 ())` must implement `FnOnce<(&'1 (),)>`, for any two lifetimes `'0` and `'1`...
   = note: ...but it actually implements `FnOnce<(&(),)>`
   = note: duplicate diagnostic emitted due to `-Z deduplicate-diagnostics=no`

error: aborting due to 2 previous errors