hphp/hack/test/typecheck/super_constraint_4.php

   1 <?hh // strict
   2 class FooBase {}
   3 class Foo extends FooBase {}
   4 class FooDerived extends Foo {}
   5 class BlahBase {}
   6 class Blah extends BlahBase {}
   7 class BlahDerived extends Blah {}
   8 function bar<Tx super Tx1, Tx1 super Foo, Ty as Ty1, Ty1 as Blah>(
   9   Ty $val,
  10   Tx $dummy,
  11 ): Tx {
  12   return $val;
  13 }
  14 function test(BlahBase $blah_base, FooDerived $foo_derived): void {
  15   bar($foo_derived, $blah_base);
  16 }