ReflectionFunction::getNamespaceName() is still broken for closures in PHP 8.4

[jlherren]

Description

The following code:

<?php
namespace TestNamespace;
$ref = new \ReflectionFunction(function (Other\Factory $factory) {
});
echo $ref->getNamespaceName(), "\n";

Resulted in this output:

But I expected this output instead (as output by PHP 8.1, 8.2 and 8.3):

TestNamespace

Also see possibly related #16122.

PHP Version

PHP 8.4.5

Operating System

Official docker image php:8.4-cli

[iluuu1994]

Hi @jlherren. This isn't really a bug. Namespaces in PHP are really just prefixes to class/function/constant names. Since closures are anonymous, they don't have a meaningful name, and thus don't have a prefix that is needed for context/disambiguation.

Nonetheless, in what context would this be relevant to you?

[jlherren]

I see how it makes sense that closures don't really have a namespace. But it's relevant because it breaks code that relied on the previous behavior present all the way back to PHP 5.3. If you say that the previous behavior was unintended or unsupported, then it may not be classified as a bug, but it still represents a rather unfortunate backward compatibility break.

One thing it breaks is laravel/serializable-closure, see laravel/serializable-closure#111 which in turn breaks php-di/php-di compiled containers for me.

[iluuu1994]

@jlherren Oh, I missed that the behavior was changed in 8.4.

@TimWolla This is caused by #13550. It explicitly dropped the namespace prefix, but I don't think we sufficiently thought about the consequences.

[TimWolla]

but I don't think we sufficiently thought about the consequences.

Indeed. It's an unfortunate and unanticipated backwards compatibility break - exactly for the reason that closures do not have a meaningful name by definition.

But I'm not sure if this is fixable now that PHP 8.4 is released and folks already adapted their code to support the closure naming format.

laravel/serializable-closure already uses the tokenizer to parse the file and look up the use statements, adding support for parsing the namespace should be a small incremental change. Generally I would expect any tool using the tokenizer to require adjustments with every new PHP version to correctly understand syntax and semantics and to me this change is no different.