Online PHP editor | vld for p6qr9

<?hh class A<T> { protected T $value; public function set(T $value) { $this->value = $value; } } class B { public function doB() : string { return "b"; } } class C extends B { public function doC() : string { return "c"; } } function foo(A<B> $a) { $a->set(new B()); } function bar(A<C> $a) { foo($a); } $v = new A<C>(); bar($v);