When is a restaurant not a "restaurant"?

The French, it seems, are getting upset about restaurants not preparing their own food on the premises, so there's  suggestion that, if this occurs in an establishment, it won't be able to call itself a "restaurant" (the link is to The Telegraph, but the article was syndicated in the AFR).

Guess the word "food lounge" wouldn't work in France?

You can imagine it, an army of inspectors out there attempting to decide whether a particular establishment had crossed some illusive line between using fresh ingredients which arrived “frozen or vacuum-packed” (which would be OK) as opposed to using "pre-prepared" food.  And would the proposed rule be breached if one item on the menu was deemed to be pre-prepared, but the others weren't?