Support returning a function when using the PhpDriver

[arjanfrans]

When defining ORM mapping using the php driver there is $metadata variable floating around in the mapping file. IDE's complain about type hinting.

It would be nice to be able to return a static function that gets the $metadata variable as an argument, so then you can write the mapping in php like this:

// config/orm/mapping/App.Entity.User.php

<?php

use Doctrine\ORM\Mapping\Builder\ClassMetadataBuilder;
use Doctrine\ORM\Mapping\ClassMetadata;

return static function (ClassMetadata $metadata): void
{
    $builder = new ClassMetadataBuilder($metadata);
    
    // ...
};

I modified the PHP driver to be able to do this (lib/Doctrine/Persistence/Mapping/Driver/PHPDriver.php):

// ...
    protected function loadMappingFile($file)
    {
        $metadata = $this->metadata;
        $mapping = include $file;
    
        if (is_callable($mapping)) {
            $mapping($metadata);
        }

        return [$metadata->getName() => $metadata];
    }
// ...

Is there any argument against doing this? The big advantage here is that you at least have a type hint.