I was at a celebration dinner last week, at a quite nice, small restaurant. I couldn’t finish the main course and I felt, as I wasn’t paying, I couldn’t ask for a doggie bag. However, I did say when they picked up my plate, that I was sorry I couldn’t finish it. They replied that they would put it by packed on another table. They did and I ate it the following day. In France since 2016 it is illegal to throw food away.
«Large French restaurants are required to offer customers "doggie bags," or takeaway containers, should they request them.»