library test;

import 'dart:async';

T f<T>() => null;

class B<T> {
  D<T> x;
}

class C<U> extends B<Future<U>> {
  E<Future<U>> get x => null;
  void g() {}
  void set x(Object x) {}
}

class D<T> {}

class E<T> extends D<T> {}

main() {}