```php class A { /** @var string */ public $foo = "bar"; public function &getString() : string { return $this->foo; } } function useString(string &$s) : void {} $a = new A(); useString($a->getString()); ``` https://phpstan.org/r/da3db779cb2ac821b7ecc9ca8d4a1b71 Expected: No error Actual: Parameter #1 $s of function useString is passed by reference, so it expects variables only. Just fixed this in Psalm, was relatively painless.