Description:
------------
PHP7 extended array_column() to support reading a column of property values from an array of objects. However, if the property contains a value that loose-equates to null, that entry is not returned in the resulting array.

Applies to all PHP7 releases; http://lxr.php.net/xref/PHP_7_0/ext/standard/array.c#3569 appears to be the cause of the bug

The code test script demonstrates this problem.

Expected result is an array containing [-1,0,1,2,null,true,false,'abc','']

Actual result is an array containing [-1,1,2,true,'abc']

The 0, null, false and empty string values are all discarded

Test script:
---------------
class myObj {
    public $prop;
    public function __construct($prop) {
        $this->prop = $prop;
    }
}

$objects = [
    new myObj(-1),
    new myObj(0),
    new myObj(1),
    new myObj(2),
    new myObj(null),
    new myObj(true),
    new myObj(false),
    new myObj('abc'),
    new myObj(''),
];

var_dump(array_column($objects, 'prop'));


Expected result:
----------------
array(9) {
  [0]=>
  int(-1)
  [1]=>
  int(0)
  [2]=>
  int(1)
  [3]=>
  int(2)
  [4]=>
  null
  [5]=>
  bool(true)
  [6]=>
  bool(false)
  [7]=>
  string(3) "abc"
  [8]=>
  string(0) ""
}
[-1,0,1,2,null,true,false,'abc','']

Actual result:
--------------
array(5) {
  [0]=>
  int(-1)
  [1]=>
  int(1)
  [2]=>
  int(2)
  [3]=>
  bool(true)
  [4]=>
  string(3) "abc"
}