error[E0308]: mismatched types
  --> $DIR/issue-107775.rs:35:16
   |
LL |         map.insert(1, Struct::do_something);
   |                    -  -------------------- this is of type `fn(u8) -> Pin<Box<dyn Future<Output = ()> + Send>> {<Struct as Trait>::do_something::<'_>}`, which causes `map` to be inferred as `HashMap<{integer}, fn(u8) -> Pin<Box<dyn Future<Output = ()> + Send>> {<Struct as Trait>::do_something::<'_>}>`
   |                    |
   |                    this is of type `{integer}`, which causes `map` to be inferred as `HashMap<{integer}, fn(u8) -> Pin<Box<dyn Future<Output = ()> + Send>> {<Struct as Trait>::do_something::<'_>}>`
LL |         Self { map }
   |                ^^^ expected `HashMap<u16, fn(u8) -> Pin<...>>`, found `HashMap<{integer}, ...>`
   |
   = note: expected struct `HashMap<u16, fn(_) -> Pin<Box<(dyn Future<Output = ()> + Send + 'static)>>>`
              found struct `HashMap<{integer}, fn(_) -> Pin<Box<dyn Future<Output = ()> + Send>> {<Struct as Trait>::do_something::<'_>}>`

error: aborting due to previous error

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