SimpleXML element comparison is broken

Description

The following code:

<?php

$xml = "<root><first/><second/><third/></root>";
$xml = simplexml_load_string($xml);
var_dump($xml->first == $xml->second);

Resulted in this output:

bool(true)

But I expected this output instead:

bool(false)

It's because the wrong node is fetched, i.e. it doesn't take into account the iterating nature of the simple xml objects. PoC fix patch (needs more testing and thinking): https://gist.github.com/nielsdos/f8e232836d72e68c5d3418116ddad877

PHP Version

PHP 5.0.0-master

Operating System

Linux

首先运行 issue 中的 SimpleXML 复现程序，并跟踪 $xml->first 与 $xml->second 的比较如何选择节点。以链接的 PoC 补丁为上下文，然后验证同一个示例报告 bool(false)，并检查相关的 SimpleXML 比较行为是否存在回归。