Description:
------------
Imagine that you have a A class.
Imagine that you have an alias B on this A class.
Imagine that you have a function/method which require a B as argument.
So, currently, it's not possible to pass a A instance as argument to this 
function/method.

Test script:
---------------
<?php

class A {}
class_alias('A', 'B');
function foo(B $b) {}
foo(new A());

Expected result:
----------------
Nothing.

Actual result:
--------------
PHP Catchable fatal error:  Argument 1 passed to foo() must be an instance of B, 
instance of A given, called in /path/to/test/file.php on line 6 and defined in 
/path/to/test/file.php on line 5