PHP7 Strict Type Hinting - see https://gist.github.com/deshack/e63358a8726b7c3e0ba13563e4f9864c for a full collection of examples about PHP5/PHP7 type hinting

php7-type-hinting-strict.php

<?php

// Force Type Hinting to do a strict type check (the same as ===).
declare(strict_types=1);

function setBool(bool $bool) {
  var_dump($bool);
}

setBool('foo');
// PHP Fatal error:  Uncaught TypeError: Argument 1 passed to setBool() must be of the type boolean, string given