library test;

typedef F<T>(T x);

class C<T> {
  void f(T x) {}
  void g1(T x) {}
  void g2(T x) {}
  void g3(C<T> c, T x) {}
  F<T> g4() => this.f;
}

class D extends C<int> {}

class E extends C<num> {
  void f(covariant int x) {}
}

test() {}
main() {}