The default under copyright law is that any substantial copy is infringement.

A license is a legal document that grants someone permission to use a work that they otherwise would not have had.

However the law also gives its own permissions to use a work - it defines what is unlawful infringement and what is lawful fair use.

The code snippets that copilot generates look more like fair use than infringement. They are small, adapted to the destination context, and usually not direct copies of one source but more of an average of many different sources. And usually the programmer does not keep the suggestion that copilot suggests unmodified - the programmer does their own editing of the snippet afterwards to further tune it to the surrounding context.

2. What if I just use leaked sources of closed source software and call it fair use?

As pointed out upthread, if it the source code is leaked then there may be trade secret protections. The GPL specifically allows the code to be posted online, so by design it is not secret.

The reverse maybe true. I may be GPL'ing a code to prevent a useful algorithm from being buried deep inside a commercial code with an incompatible license. What makes it a "trade secret" level code? I have a 25 line algorithm which is worthy of its own paper. What if I open its reference implementation with AGPLv3+?

I have no problems with you reading the paper, and implementing it. I don't obfuscate my papers, but I put the implementation out with AGPLv3+. You can't use that in a codebase with an incompatible license. I expect and want you respect the license of my implementation.

> The code snippets that copilot generates look more like fair use than infringement. They are small, adapted to the destination context, and usually not direct copies of one source but more of an average of many different sources. And usually the programmer does not keep the suggestion that copilot suggests unmodified - the programmer does their own editing of the snippet afterwards to further tune it to the surrounding context.

Emphasis mine. First, there's no consensus on fair use, yet. Second they may be direct copies of the code. Third, they're remixed with other code pieces, which makes it a derivative work of many code pieces at once, then lastly, programmer re-derives the derived work. Which is clearly a derivative of GPL code, which brings in GPL license with itself (if what copilot derives the code from GPL licensed repositories, which it does).

I have no problem with Copilot as a technology. I have no problems with other licenses, which are not breached when used by Copilot and derived and used. The point which makes my blood boil is copilot using this GPL corpus, and don't admitting it publicly, breaching the terms of GPL en masse, and outright ignoring it. Then feeding this GPL derived code to any and all projects which pay for a copilot membership, and calling it a day.