Infinite loop when trying to copy "recursive" array

[sebastianbergmann]

It would be nice if DeepCopy could detect array structures that lead to infinite loops.

$ composer info | sort -d
myclabs/deep-copy 1.10.2 Create deep copies (clones) of your objects

$ php -v                           
PHP 8.0.9 (cli) (built: Jul 29 2021 12:53:58) ( NTS gcc x86_64 )
Copyright (c) The PHP Group
Zend Engine v4.0.9, Copyright (c) Zend Technologies

segfault.php

<?php declare(strict_types=1);
require __DIR__ . '/vendor/autoload.php';

use DeepCopy\DeepCopy;

$a   = [];
$a[] = &$a;

$b = [
    'RECURSION' => [
        'data' => $a,
    ],
];

$deepCopy = new DeepCopy;
$deepCopy->skipUncloneable(false);

$deepCopy->copy($b);

Without Xdebug

$ php segfault.php              
[1]    49178 segmentation fault (core dumped)  php segfault.php

With Xdebug

$ php segfault.php                 

Fatal error: Uncaught Error: Xdebug has detected a possible infinite loop, and aborted your script with a stack depth of '256' frames in /tmp/segfault/vendor/myclabs/deep-copy/src/DeepCopy/TypeMatcher/TypeMatcher.php on line 27

[mnapoli]

Thanks for the report.

I gave it a quick try and I honestly don't see how to achieve this.

To detect/avoid recursions in object graphs, we use a hash map of spl_object_hash() -> object.

I don't see how to do a similar hash map with primitive values 🤔

[sebastianbergmann]

No worries, and feel free to close this report. I ran into this while working on some PHPUnit internals and suddenly a test for a weird edge case that uses such a data structure triggered this crash. I'll investigate this on my end, maybe we can simply delete the test (and document the fact that such weird data structures are not supported).