You should expect to carry on luggage that is in conformity with the published Air France guidelines. I thought all luggage makers kind of settled on advertising roll-on bags as carry-ons if it met the industry standard guidelines, with special designations for the smaller LCC dimensions ?
Your hand baggage must not exceed the following dimensions: 55 x 35 x 25 cm / 21.7 x 13.8 x 9.9 in (including pockets, wheels and handles).
In the Economy cabin, the combined weight of your hand baggage item and accessory must not exceed 12 kg / 26 lb.
If you're traveling in the Premium Economy, Business or La Première cabins, the combined weight of your hand baggage items and accessory must not exceed 18 kg / 40 lbs. Your travel cabin is shown on your ticket.
I wouldn't say AF is a real stickler like the LCC, but the flight is full, they might verify the size at the gate. So when in doubt, I'd just check it.