main.dart

abstract class C {
  abstract int x1;
  abstract var y1;
  abstract final z;
  abstract final int u1;
  abstract covariant int v1;
  abstract covariant var w;
}

class D extends C {
  int x1 = 0;
  var y1;
  final z = 0;
  final int u1 = 0;
  covariant int v1 = 0;
  covariant var w;
}

void main() {
  final d = D();
  print(d.x1);
  print(d.y1);
  print(d.z);
  print(d.u1);
  print(d.v1);
  print(d.w);
}