The quiz says: ____ les gars! Thanks for coming guys!
The answer is Merci d'etre venus
This is clearly correct in the usual situation where the guys have come and are being thanked for it.
But suppose that the guys had promised to come and were being thanked in advance for it? The same English sentence would work for that situation, even if it would be more explicit if we said "Thanks for agreeing to come, guys". How would the French look in that case?