Is there advantage on a non-adjacent attack against an unconscious creature?

Question

The unconscious condition states the following two effects (PHB 292):

• The creature drops whatever it's holding and falls prone.

• Attack rolls against the creature have advantage

Under the prone condition it says (ibid):

• An attack roll against the creature has advantage if the attacker is within 5 feet of the creature. Otherwise, the attack roll has disadvantage.

The rules of advantage/disadvantage include the following paragraph (PHB 171):

• If circumstances cause a roll to have both advantage and disadvantage, you are considered to have neither of them, and you roll one d20. This is true even if multiple circumstances impose disadvantage and only one grants advantage or vice versa. In such a situation, you have neither advantage nor disadvantage.

The question then is, does one receive advantage for a non-adjacent attack against an unconscious foe?

Are the effects of unconsciousness written to define the condition as it is, or are we meant to "calculate" the full truth by recognizing that the unconscious advantage and prone disadvantage (of non-adjacent attacks) should cancel out?

Answer 1

The rules that you've quoted are pretty clear. You gain advantage when attacking unconscious creatures, and you gain disadvantage when attacking prone creatures from further than 5 feet away. If you have both advantage and disadvantage — you're attacking an unconscious creature from further than 5 feet away — you get neither, instead.

Answer 2

The advantage and the disadvantage cancel out here

A creature who is affected by sleep is both unconscious and prone.

As the rules for prone that you quoted say, attacking a prone creature from more than 5 feet away causes disadvantage.¹

An attack roll against the [prone] creature has advantage if the attacker is within 5 feet of the creature. Otherwise, the attack roll has disadvantage. (PHB 292)

However, all attack rolls also get advantage from the unconscious condition.

Attack rolls against the [unconscious] creature have advantage (PHB 292)

Since you can't have both on the same roll, they cancel out and you instead have neither.

If circumstances cause a roll to have both advantage and disadvantage, you are considered to have neither of them, and you roll one d20. This is true even if multiple circumstances impose disadvantage and only one grants advantage or vice versa. In such a situation, you have neither advantage nor disadvantage. (Basic Rules)

And if there was any doubt still left, it appears that Jeremy Crawford also unofficially agrees on Twitter.

Of course, if you can get within 5 feet of the unconscious creature, you do have advantage (twice) which reduces to a simple advantage on the roll.

---

^{1 - As pointed out by @NautArch this interestingly still applies to melee weapons with reach being used to attack a creature from more than 5 feet away. That attack will still have disadvantage.}