error[E0038]: the trait alias `SelfInput` is not dyn compatible
  --> $DIR/self-in-generics.rs:8:19
   |
LL | pub fn f(_f: &dyn SelfInput) {}
   |                   ^^^^^^^^^ `SelfInput` is not dyn compatible
   |
note: for a trait to be dyn compatible it needs to allow building a vtable
      for more information, visit <https://doc.rust-lang.org/reference/items/traits.html#dyn-compatibility>
  --> $DIR/self-in-generics.rs:6:23
   |
LL | pub trait SelfInput = Fn(&mut Self);
   |           ---------   ^^^^^^^^^^^^^
   |           |           |
   |           |           ...because it uses `Self` as a type parameter
   |           |           ...because it uses `Self` as a type parameter
   |           this trait is not dyn compatible...
help: consider using an opaque type instead
   |
LL - pub fn f(_f: &dyn SelfInput) {}
LL + pub fn f(_f: &impl SelfInput) {}
   |

error: aborting due to 1 previous error

For more information about this error, try `rustc --explain E0038`.