Generics oddness

main.dart

class A {}

class B extends A {
  String b() {
    return 'b';
  }
}

class C<T extends A> {
  const C(this.c);
  
  final T c;
  
  String? someMethod() {
    if (c is B) {
      return c.b(); // Method b isn't defined for the type unknown.
    }
  }

  String? someMethod2() {
    final _c = c;
    
    if (_c is B) {
      return _c.b();
    }
  }
}

void main() {
  print(C<B>(B()));
}