prefix = Expr[Nothing]({
  final class $anon extends AnyRef with Base {
    def <init>(): <$anon: Base> = {
      $anon.super.<init>();
      ()
    };
    <empty>
  };
  new $anon()
})
it works
prefix = Expr[Nothing](Macros)
it works
prefix = Expr[Nothing](new Macros())
it works