[php-src] Issue #7740: Access behavior of SimpleXMLElement changes when element has sibling

Issue: https://github.com/php/php-src/issues/7740 Author: LeonMelis ### Description This was a hard bug to name, and hence it was hard to search for. I couldn't find a similar report, but if this was already reported, my apologies. The behavior when accessing a property in a SimpleXMLElement object seems to be influenced by the element having 'siblings' or not. This behavior can be observed with xdebug, as well as using print_r or var_dump. In the example, when accessing $xml_correct->bar the result is as expected. However, adding a sibling 'fiz' to element 'bar' in $xml_bug will change the result when accessing $xml_bug->bar. Suddenly, $xml_bug->bar becomes an array. It only does this when $xml_bug->bar is accessed directly. When accessing $xml_bug (or viewing it in the debugger), the 'bar' property appears as expected. I have tested this in php 7.2, 7.3, 7.4 and 8.0, all show the same result. 3v4l.org shows the same output: https://3v4l.org/0EGhe This might be a bug in libxml, or php, I'm not sure. ```php <?php /** * This demos a (possible) bug in PHP, which is observed in PHP 7.2, 7.3, 7.4 and 8.0 (not yet tested on 8.1). * * Access behaviour of a SimpleXMLElement changes if that node has a sibling. * * In this example, adding 'fiz' to 'foo' (which is the outer node) will change behaviour when accessing 'bar' (an inner node). */ $xml_correct = new SimpleXMLElement('<foo><bar><baz/></bar></foo>'); print_r($xml_correct); // As expected print_r($xml_correct->bar); // As expected, $bar contains property $baz, which is an empty SimpleXMLElement $xml_bug = new SimpleXMLElement('<foo><bar><baz/></bar><fiz/></foo>'); print_r($xml_bug); // As expected, property $bar is equal to that observed in print_r($xml_correct) print_r($xml_bug->bar); // UNEXPECTED: property $bar is an array, containing one SimpleXMLElement with property $baz which is an empty SimpleXMLElement ``` Resulted in this output: ``` // output of print_r($xml_bug->bar): SimpleXMLElement Object ( [0] => SimpleXMLElement Object ( [baz] => SimpleXMLElement Object ( ) ) ) ``` But I expected this output instead: ``` // output of print_r($xml_correct->bar): SimpleXMLElement Object ( [baz] => SimpleXMLElement Object ( ) ) ``` ### PHP Version 7.4 8.0 ### Operating System Linux