howto get child type returned, not parent

[rdefaux]

I read PHPStan documentation and tried a lot, but I don't understand how to get the child class detected by PHPStan in this code, or even if it is possible...

abstract class Bar {
}

class Foo extends Bar 
{
}

class Foofoo extends Bar 
{
}

class Baz {
    private Bar $_bar;
    
    /**
     * @param Bar $bar
     *
     * @return void
     */
    public function setBar(Bar $bar)
    {
        $this->_bar=$bar;
    }

    /**
    *
    * @return Bar
    */
    public function bar(): Bar
    {
        return $this->_bar;
    }
}

$baz=new Baz();
$baz->setBar(new Foo());
\PHPStan\dumpType($baz->bar());     // return type is Bar, I would like Foo
$baz->setBar(new Foofoo());
\PHPStan\dumpType($baz->bar());     // return type is Bar, I would like Foofoo

The link to the playground : https://phpstan.org/r/53aebcc3-717b-445c-8715-0f277151270b

Thanks for your help !

[ondrejmirtes]

The only way to achieve this is with generics: https://phpstan.org/r/5ed2bf49-e9fe-43b6-b279-182458ff358a

[rdefaux]

Thank you for your quick reply.