function sayHello(): void
{
	$foo = [5,6,7];
	foreach ($foo as $i => $foo) {
		// ...			
	}
	// here is $foo int not array.
	bar($foo);  // TypeError: Argument 1 passed to bar() must be of the type array, integer given
}
	
/**
 * @param int[] $x
 * @return int[]
 */
function bar(array $x): array {
	return $x;
}
	
sayHello();