Description:
------------
It seems that is callable behavior is changed.
In PHP < 8, is_callable() includes needed class file through autoloader and returns .
In PHP 8 it returns false.


$callback = ['\Path\To\ClassName, 'methodName'];
is_callable($callback); // always returns false in PHP 8
$callback(); // but loads needed files through autoloader and executes the callback

Expected result:
----------------
It should loads needed files through autoloader and returns a valid value.

Actual result:
--------------
Always returns false, no matter if it is really callable or not.