error[E0308]: mismatched types
  --> $DIR/issue-78722.rs:12:20
   |
LL | type F = impl core::future::Future<Output = u8>;
   |          -------------------------------------- the expected opaque type
...
LL |         let f: F = async { 1 };
   |                -   ^^^^^^^^^^^ expected opaque type, found a different opaque type
   |                |
   |                expected due to this
   |
  ::: $SRC_DIR/core/src/future/mod.rs:LL:COL
   |
LL | pub const fn from_generator<T>(gen: T) -> impl Future<Output = T::Return>
   |                                           ------------------------------- the found opaque type
   |
   = note: expected opaque type `impl Future<Output = u8>`
              found opaque type `impl Future<Output = [async output]>`
   = note: distinct uses of `impl Trait` result in different opaque types

error: aborting due to previous error

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