1--TEST--
2References to objects for which Serializable::serialize() returned NULL should use N;
3--FILE--
4<?php
5
6class NotSerializable implements Serializable {
7    public function serialize() {
8        return null;
9    }
10
11    public function unserialize($serialized) {
12    }
13}
14
15$obj = new NotSerializable();
16$data = [$obj, $obj];
17var_dump($s = serialize($data));
18var_dump(unserialize($s));
19
20?>
21--EXPECTF--
22Deprecated: %s implements the Serializable interface, which is deprecated. Implement __serialize() and __unserialize() instead (or in addition, if support for old PHP versions is necessary) in %s on line %d
23string(18) "a:2:{i:0;N;i:1;N;}"
24array(2) {
25  [0]=>
26  NULL
27  [1]=>
28  NULL
29}
30