hphp/hack/test/typecheck/super_constraint_11.php

   1 <?hh // strict
   2 // Copyright 2004-present Facebook. All Rights Reserved.
   3
   4 interface MyWidget<Tu> {}
   5
   6 // Create a pair of unrelated types
   7 class WidgetParent {}
   8 class NotWidgetParent {}
   9
  10 class MyWidgetA implements MyWidget<WidgetParent> {}
  11 class MyWidgetB implements MyWidget<NotWidgetParent> {}
  12
  13 class MyContainer {
  14   public function add<T super WidgetParent>(MyWidget<T> $task): void {}
  15 }
  16
  17 function test_hhvm_super(): void {
  18   $container = new MyContainer();
  19   // So T = WidgetParent
  20   $container->add(new MyWidgetA()); // this should pass the type checker
  21   // So T = NotWidgetParent
  22   $container->add(new MyWidgetB()); // this should be flagged as an error
  23 }