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Bug #80659 unexp. Typecast at not fitting function return type declaration
Submitted: 2021-01-22 09:54 UTC Modified: 2021-01-22 16:08 UTC
From: thomas dot bindewald at metanet dot ch Assigned:
Status: Not a bug Package: Class/Object related
PHP Version: 8.0.1 OS: Linux 4.19.0-13-amd64 x86_64 GNU
Private report: No CVE-ID: None
 [2021-01-22 09:54 UTC] thomas dot bindewald at metanet dot ch
Description:
------------
Environment: Debian 10 Linux
PHP-Packages from https://packages.sury.org/php/

---

PHP 8.0.1 (cli) (built: Jan 12 2021 13:59:46) ( NTS )
Copyright (c) The PHP Group
Zend Engine v4.0.1, Copyright (c) Zend Technologies
    with Zend OPcache v8.0.1, Copyright (c), by Zend Technologies
    with Xdebug v3.0.1, Copyright (c) 2002-2020, by Derick Rethans


Test script:
---------------
<?php
​function foooo() : false|string|stdClass {
	$xmlString = '<xml><woche><Montag>Erdbeermarmelade</Montag><Dienstag>Lindenbluetenhonig</Dienstag></woche></xml>';
	$xmlObj = new SimpleXMLElement($xmlString);
	var_dump($xmlObj);
	return $xmlObj;
}
​$wert = foooo();
var_dump($wert);
exit;


Expected result:
----------------
TypeError Exception being thrown.


Actual result:
--------------
XML-Object silently being casted to empty string.

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 [2021-01-22 10:24 UTC] thomas dot bindewald at metanet dot ch
There could be discussed, if returning the SimpleXMLElement would be okay, as the return type declaration allows "stdClass" (?).
But a silent "empty string"-conversion/casting is definitely unexpected.
 [2021-01-22 10:26 UTC] nikic@php.net
-Status: Open +Status: Not a bug
 [2021-01-22 10:26 UTC] nikic@php.net
This is correct, because your return type includes "string" and SimpleXMLElement can be converted to string.

If you don't want implicit conversions, use declare(strict_types=1).
 [2021-01-22 10:57 UTC] 3g3g3g4 at egeg3g dot com
there is nothing to be discussed - stdClass is not compatible and when you want to allow any class simply use "object"

no matter what, you expected a type error but didn't tell php that you expect strict mode
 [2021-01-22 16:08 UTC] thomas dot bindewald at metanet dot ch
after the first hint (thanks @ nikic) I was able to research the topic deeper and found the relevant aspects. I was no longer aware of the details.
Thanks & I apologize for my bringing up this issue.


/close
 
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