error: implementation of `FnOnce` is not general enough
  --> $DIR/higher-ranked-auto-trait-14.rs:20:5
   |
LL | /     async move {
LL | |         let xs = unique_x.union(&cached)
LL | |             // .copied() // works
LL | |             .map(|x| *x) // error
LL | |             ;
LL | |         let blah = val.blah(xs.into_iter()).await;
LL | |     }
   | |_____^ implementation of `FnOnce` is not general enough
   |
   = note: closure with signature `fn(&'0 u32) -> u32` must implement `FnOnce<(&'1 u32,)>`, for any two lifetimes `'0` and `'1`...
   = note: ...but it actually implements `FnOnce<(&u32,)>`

error: implementation of `FnOnce` is not general enough
  --> $DIR/higher-ranked-auto-trait-14.rs:20:5
   |
LL | /     async move {
LL | |         let xs = unique_x.union(&cached)
LL | |             // .copied() // works
LL | |             .map(|x| *x) // error
LL | |             ;
LL | |         let blah = val.blah(xs.into_iter()).await;
LL | |     }
   | |_____^ implementation of `FnOnce` is not general enough
   |
   = note: closure with signature `fn(&'0 u32) -> u32` must implement `FnOnce<(&'1 u32,)>`, for any two lifetimes `'0` and `'1`...
   = note: ...but it actually implements `FnOnce<(&u32,)>`
   = note: duplicate diagnostic emitted due to `-Z deduplicate-diagnostics=no`

error: aborting due to 2 previous errors