extension A on C {
  void method() {}
  int get getter => 42;
  void set setter(int value) {}
  int get property => 42;
  int operator +(int i) => i;
  int operator -() => 0;
  int operator [](int i) => i;
}

extension B on C {
  void method() {}
  int get getter => 42;
  void set setter(int value) {}
  void set property(int value) {}
  int operator +(int i) => i;
  int operator -() => 0;
  void operator []=(int i, int j) {}
}

class C {}

errors(C c) {}
main() {}