hphp/hack/test/typecheck/generic_subtyping2.php

   1 <?hh // strict
   2 /**
   3  * Copyright (c) 2014, Facebook, Inc.
   4  * All rights reserved.
   5  *
   6  * This source code is licensed under the MIT license found in the
   7  * LICENSE file in the "hack" directory of this source tree.
   8  *
   9  *
  10  */
  11
  12 class I {}
  13 class A extends I {}
  14 class B extends I {}
  15 class UnrelatedClass {}
  16
  17 function foo<T as I>(T $x): void {}
  18
  19 function test(bool $b): void {
  20   if ($b) {
  21     $y = new B();
  22   } else {
  23     $y = new UnrelatedClass();
  24   }
  25   foo($y);
  26 }