http_build_query() skips Stringable params

Description

The following code:

<?php 

$params = [
    'param1' => 1,
    'param2' => new Class {
        public function __toString():string {return 'test';}
    }
];

echo http_build_query($params);

foreach ($params as $k => &$v) $params[$k] = (string) $v;

echo http_build_query($params);

Resulted in this output:

param1=1

But I expected this output instead:

param1=1&param2=test

... as __toString() should have been implicitly called on the object. The ugly manual conversion shouldn't be necessary.

PHP Version

PHP 8.1

Operating System

Any