I have been following a Facebook conversation on which McDonald's fries around the world are fully gluten free. I don't think I have been in a McDonald's for about thirty years (and I was vegetarian the one time I did that, so you can imagine I ate well!), but I know my niece uses them as their meat patties are gf.
I had a quick look on the web. Their ingredients page is very easy to use and states that their fries are completely gluten free. They are cooked in dedicated frying vats. I don't eat fried food unless I can be sure a dedicated fryer that isn't used for any breaded items is used, so this is useful to know.