SimpleXMLElement - SimpleXMLIterator::var is not defined - After property_exists check

[lsv]

With the following, I get a

Instance property SimpleXMLIterator::$projectFiles is not defined (see https://psalm.dev/039)

Now, I already check that $projectFiles is a property, with my property_exists method

<?php
$xml = <<<XML
<?xml version="1.0"?>
<psalm>
    <projectFiles>
        <directory name="src" />
        <ignoreFiles>
            <directory name="vendor" />
        </ignoreFiles>
    </projectFiles>
</psalm>
XML;

$xmlObject = simplexml_load_string($xml);
if ($xmlObject instanceof SimpleXMLElement) {
    $projectFiles = $xmlObject->children('projectFiles', true);
    if (property_exists($projectFiles, 'projectFiles')) {
        if ($projectFiles->projectFiles instanceof SimpleXMLElement) {
            return true;
        }
    }
}

Isnt this a false positive call, or is there a way to get rid of that check?

[lsv]

Reproduced: https://psalm.dev/r/ac48378869

[psalm-github-bot]

I found these snippets:

https://psalm.dev/r/ac48378869

<?php
$xml = <<<XML
<?xml version="1.0"?>
<psalm>
    <projectFiles>
        <directory name="src" />
        <ignoreFiles>
            <directory name="vendor" />
        </ignoreFiles>
    </projectFiles>
</psalm>
XML;

$xmlObject = simplexml_load_string($xml);
if ($xmlObject instanceof SimpleXMLElement) {
    $projectFiles = $xmlObject->children('projectFiles', true);
    if (property_exists($projectFiles, 'projectFiles')) {
        if ($projectFiles->projectFiles instanceof SimpleXMLElement) {
            return true;
        }
    }
}

Psalm output (using commit f7a6336):

ERROR: UndefinedPropertyFetch - 18:13 - Instance property SimpleXMLIterator::$projectFiles is not defined

[orklah]

You can add

<universalObjectCrates>
        <class name="SimpleXMLIterator"/>
    </universalObjectCrates>

in your config file to resolve this (Psalm will consider any property as existing).

It should probably be something more integrated in Psalm though so I'll let this issue open

[weirdan]

is there a way to get rid of that check?

You can also use isset(): https://psalm.dev/r/4ef9699b4f

[psalm-github-bot]

I found these snippets:

https://psalm.dev/r/4ef9699b4f

<?php
$xml = <<<XML
<?xml version="1.0"?>
<psalm>
    <projectFiles>
        <directory name="src" />
        <ignoreFiles>
            <directory name="vendor" />
        </ignoreFiles>
    </projectFiles>
</psalm>
XML;

$xmlObject = simplexml_load_string($xml);
if ($xmlObject instanceof SimpleXMLElement) {
    $projectFiles = $xmlObject->children('projectFiles', true);
    if (isset($projectFiles->projectFiles)) {
        if ($projectFiles->projectFiles instanceof SimpleXMLElement) {
            return true;
        }
    }
}

Psalm output (using commit f7a6336):

No issues!

[lsv]

Thanks @weirdan
Though, shouldnt property_exists and isset give the same result?

[weirdan]

It should.

[orklah]

The case for SimpleXMLIterator is fixed by PR above. The case for property_exists is a duplicate of #4182