Default arguments and type hinting

Run these three:

php -r 'function a(array $a){}; a(NULL);'
php -r 'function a(array $a = NULL){}; a(NULL);'
php -r 'function a(array $a = FALSE){}; a(FALSE);'

Results:

PHP Catchable fatal error:  Argument 1 passed to a() must be of the type array, null given, called in Command line code on line 1 and defined in Command line code on line 1

-nothing-
PHP Fatal error:  Default value for parameters with array type hint can only be an array or NULL in Command line code on line 1