output.txt

test.php:9:10,19: Typing error (Typing[4110])
  test.php:3:30,33: This is a nullable type
  test.php:9:19,19: It is incompatible with an int

test.php

<?hh // strict

function returns_nullable(): ?int {
  return null;
}

function use_nullable(): bool {
  $value = returns_nullable();
  return $value > 1;
}