Description:
------------
You cannot directly execute a closure. Prevents code such as

<?php

$condition ? function () {
  // path a
}() : function () {
  // path b
}();

Which can be useful in various cases.

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

function () { echo 'test'; }();

function () { echo 'tickle'; }->__invoke();

Expected result:
----------------
testtickle

Actual result:
--------------
PHP Parse error:  syntax error, unexpected '->' (T_OBJECT_OPERATOR) in php shell 
code on line 1

PHP Parse error:  syntax error, unexpected '->' (T_OBJECT_OPERATOR) in php shell 
code on line 1