DOMDocument::loadHTML fails with "Memory allocation failed" on self-closing elements

[aliechti]

Description

The following code:

<?php
declare(strict_types=1);

$content = '<div/><div/>';

$dom = new \DOMDocument();
$dom->loadHTML(
    $content,
    LIBXML_HTML_NOIMPLIED | LIBXML_HTML_NODEFDTD
);

echo $dom->saveHTML();

Resulted in this output:

PHP Warning:  DOMDocument::loadHTML(): Memory allocation failed in Entity, line: 1 in /mnt/projects/limsophy-web/test.php on line 7
<div></div>

But I expected this output instead:

<div><div></div></div>

PHP Version

PHP 8.4.4

Operating System

No response

[ndossche]

This doesn't reproduce for me.
@aliechti Please share your libxml version and which operating system you use
@devnexen Please also share yours.

[devnexen]

sure: 2.12.7 on ubuntu 24.10. is a libxml issue it seems, can reproduce with packaged version 8.3.

[ndossche]

Indeed, not a PHP bug but an (already-fixed) libxml bug. This was fixed in libxml commit GNOME/libxml2@abd7418
I.e. You should use libxml version 2.13.x or more modern and then it will be fixed.