Description:
------------
https://3v4l.org/1ARiM

Seems to be broken since 7.x, worked in 5.6. Probably the switch from const char* to zend_string* for /internal/ arg names, but not user names, broke it.

Test script:
---------------
<?php

var_dump((new ReflectionFunction('sin'))->getClosure());

Expected result:
----------------
object(Closure)#2 (1) {
  ["parameter"]=>
  array(1) {
    ["$number"]=>
    string(10) "<required>"
  }
} 

Actual result:
--------------
object(Closure)#2 (1) {
  ["parameter"]=>
  array(1) {
    ["$p���x�����������X���@���T���t������|�����T���<���Internal zval's can't be arrays, objects or resources"]=>
    string(10) "<required>"
  }
}