hphp/hack/test/typecheck/function_pointer/projected_type_const_undefined.php

   1 <?hh
   2
   3 abstract class MyBox {
   4   abstract const type TInner;
   5   abstract public function set(this::TInner $_): void;
   6 }
   7
   8 class IntBox extends MyBox {
   9   const type TInner = int;
  10   public function set(int $_): void {}
  11 }
  12
  13 function set_a_box<TBox as MyBox with { type TInner = TVal }, TVal>(
  14   TBox $b,
  15   TVal $v,
  16 ): void {
  17   $b->set($v);
  18 }
  19
  20 function test(): void {
  21   $fun = set_a_box<>;
  22 }