That's a good point. I was thinking that during the curation phase of the dataset they should check for a LICENSE.txt file in the repo, and just batch exclude all copyleft/copyright containing repositories. This obviously won't handle every case as you say, and when it does generate copyleft code it will fail to attribute, but hopefully not having copyleft code in its dataset or less of it reduces the chance it generates code that perfectly satisfies its loss function by being exactly like something its seen before.

The main problem I see with generating attribution is that the algorithm obviously doesn't "know" that it's generating identical code. Even in the original twitter post, the algorithm makes subtle and essentially semantically synonymous changes (like the changing the commenting style). So for all intents and purposes it can't attribute the function because it doesn't know _where_ it's coming from and copied code is indistinguishable from de novo code. Copilot will probably never be able to attribute code short of exhaustively checking the outputs using some symbolical approach against a database of copyleft/copyrighted code.