enum E {
  case c
}

protocol P {
  var erasedID: AnyHashable { get }
}

struct S<ID: Hashable> {
  var id: ID
}

extension S: P {
  var erasedID: AnyHashable { id }
}

let a = S<AnyHashable>(id: E.c)
print(a.id.debugDescription)
print(a.erasedID.debugDescription)
print(a.id == a.erasedID)

let b = S<E>(id: E.c)
print(b.id)
print(b.erasedID.debugDescription)
print(b.id as AnyHashable == b.erasedID)

AnyHashable(E.c)
AnyHashable(AnyHashable(E.c))
false

c
AnyHashable(E.c)
true

var erasedID: AnyHashable {
  let erased = id as AnyHashable
  if let base = erased.base as? AnyHashable {
    return base
  }
  return id
}