You’re probably making the already-classic blunder here, thinking that the GPL is somehow special. If the license requires attribution (which almost all do), yo

You’re probably making the already-classic blunder here, thinking that the GPL is somehow special. If the license requires attribution (which almost all do), you’re stuck if the “fair use” exemption Copilot claims falls down. The quantity of public-domain or public-domain-equivalent-licensed code out there is almost certainly not enough to train such a tool (by several orders of magnitude, most likely—you can tweak an existing model with small amounts of code, but I believe generating a useful model from scratch will require a lot more than you are likely to find). This kind of thing cannot succeed legally without the fair use exemption from copyright.