Constant Scalar Expressions

<?php
const ONE = 1;
const TWO = ONE * 2;

class C {
    const THREE = TWO + 1;
    const ONE_THIRD = ONE / self::THREE;
    const SENTENCE = 'The value of THREE is '.self::THREE;

    public function f($a = ONE + self::THREE) {
        return $a;
    }
}

echo (new C)->f()."\n";
echo C::SENTENCE;
?>

<?php
const ONE = 1;
const TWO = ONE * 2;

class C {
    const THREE = TWO + 1;
    const ONE_THIRD = ONE / self::THREE;
    const SENTENCE = 'The value of THREE is '.self::THREE;

    public function f($a = ONE + self::THREE) {
        return $a;
    }
}

echo (new C)->f()."\n";
echo C::SENTENCE;
?>