Description:
------------
Just recently I found out that type declaration does not support aliases[1]. This is a piece of information that is currently missing in the documentation[2]. Therefore, I propose to add this information to the documentation. Maybe together with my test script and a detailed explanation of what the error means.

[1]
http://marc.info/?l=php-general&m=145030898711430&w=2
[2]
http://php.net/manual/en/functions.arguments.php#functions.arguments.type-declaration

Test script:
---------------
<?php 
	function bar(boolean $foo): boolean{return $foo;}
	var_dump(bar((bool)true));
?>

Expected result:
----------------
bool(true)

Actual result:
--------------
PHP Fatal error:  Uncaught TypeError: Argument 1 passed to bar() must be an instance of boolean, boolean given, called in ./example4.php:2
Stack trace:
#0 ./example4.php(3): bar(true)
#1 {main}
  thrown in ./example4.php on line 2