Description:
------------
https://3v4l.org/edgYU/rfc#vgit.master

Internal array pointer can not be modified for readonly properties.
This strongly limits the possibility of implementing Iterator interfaces using them. The following example is simpler, but still follows the same principle.

These properties would be much more useful if the pointer remained free, as the data itself is not impacted.

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

class A {

    public function __construct (public readonly array $ary = [0,1,2,3])  {}
}

$obj = new A;

var_dump(current($obj->ary));

next($obj->ary);

var_dump(current($obj->ary));


Expected result:
----------------
int(0)
int(1)

Actual result:
--------------
int(0)

Fatal error: Uncaught Error: Cannot modify readonly property A::$ary in /in/CBCan:12
Stack trace:
#0 {main}
  thrown in /in/CBCan on line 12

Process exited with code 255.