Quote Originally Posted by BloodSnake'sCha View Post
I have to point out it require an attack, not an attack roll.
I can see it why it can be understood like this(the text use the following words:"if you have advantage on the attack roll. "
But it look like a specific rule for me.

We have to known options for attacks with no attack rolls(grapple and shove) but for now we have no finesse or range weapon I know about that can be used for those attacks.
grapple and shove are specifically referred to as "special attacks"

many folks, including WOTC devs, define attack as requiring the attack roll.
Quote Originally Posted by PHB, Making an Attack
Resolve the Attack. You make the Attack roll.
Quote Originally Posted by PHB, Attack Rolls
When you make an Attack, your Attack roll determines whether the Attack hits or misses.

While in general, I don't agree with the attack roll interpreation, in this case, I would treat piercing arrow like a save Spell, not an attack.