Not possible. Such licenses are founded upon copyright doctrine, and copyright doesn’t protect against learning, natural or machine. As it stands (and this can certainly change), legal consensus in general (regardless of jurisdiction) is that if you publish your code where they can reach it, they can use it.
So would it (theoretically) be legal to train on the JS files services like gmail.com serve to the client? What about decompiled output of proprietary software like certain files in Windows and macOS?
Except for any laws or restrictions against decompiling, it would legally be no different than the GPL case. Although personally I think since co-pilot is capable of redistributing the code, the question of whether the GPL permits the specific usage is still unclear.
