Does Green-Flame Blade qualify for learning from Spell Sniper?

Question

The Spell Sniper feat gives you a cantrip among other things:

You learn one cantrip that requires an attack roll

Does Green-Flame Blade fits this requirement? No direct attack roll is used as in Thorn Whip, but still an attack roll is necessary for the cantrip to work.

So the question is, if you can learn GFB with this feat, not if its range is doubled.

Answer 1

Yes, You can learn Green Flame Blade with Spell Sniper

We know from Jeremy Crawford's tweet that

Spell Sniper does work green-flame blade.

At least as far as increasing the range is concerned. Spell Sniper specifically says:

When you cast a spell that requires you to make an attack roll, the spell’s range is doubled.

Since Green Flame Blade is confirmed to work with the range increase of spell sniper, then Green Flame Blade must be a spell and it must require an attack roll. If it didn't meet these requirements, it wouldn't be valid for a range increase.

The cantrip that you learn from the spell, as it has been pointed out, is:

one cantrip that requires an attack roll

Well, Green Flame Blade is a cantrip. And we know that it requires an attack roll, because it fulfills that same requirement for the range increase in the other benefit. And Green Flame Blade is on several of the allowed class spell lists. Since there are no other restrictions, Green Flame Blade meets all requirements to be learned from this feat.

Answer 2

Yes, you can use Spell Sniper to learn green flame blade.

According to Jeremy Crawford (see this tweet):

Spell Sniper does work [with] green-flame blade.

Keep in mind that only the range of the spell will be doubled from 5 feet to 10 feet. The flame will still only leap 5 feet from the initial target.

A formal justification if that is not clear from the ruling.

Crawford indicates that Spell Sniper "works" with green flame blade, which in the context of that Twitter conversation refers to the range-doubling part of Spell Sniper. However, the range-doubling part's text has exactly the same requirement as the cantrip-learning part: a spell that requires an "attack roll." Therefore, if green flame blade qualifies for one part of Spell Sniper, it also qualities for the other part with the same requirements. Hence, if Spell Sniper can double the range of green flame blade then Spell Sniper can allow the character to learn green flame blade too. QED