Sure, there would be software with code not published, but if it was ever leaked which it often is, you could do whatever you want with it.
But in a world where copyright does exist, copyleft is a tool to fight back.
The GPL is entirely dependent on copyright. Rather than pretend copyright doesn't exist, the GPL turns it in the other direction. By violating the GPL, Copilot is still violating copyright.
And then if we can close that loop by taking their proprietary software and feeding it into a NN to re-liberate it isn't that a net win for software freedom?
Today crossing the sourcecode->bytecode veil effectively obfuscates the implementation beyond most human's ability to modify the software. Humans work best in sourcecode. Nothing saying our AI overlords won't be able to work well in bytecode or take it in the other direction.
I guess what I'm saying is, today a compiler is a one-way door for software freedom. Once it goes through the compiler, we lose a lot of freedom without a massive human investment or the original source code. Maybe that door is about to become a two way door with copyright law supporting moving back and forth through that door?
From where? They aren't publishing it. That's literally the meaning of proprietary.
Colloquially, "proprietary software" means closed-source. You can definitely put it in context where it means "copyright without license"; but outside that context, the colloquial meaning is enough.
That’s literally not the definition of proprietary.
You download proprietary software when you navigate to (nearly) every webpage. Just because a website like HN sends you (possibly unobfuscated) HTML, CSS, and JS over the wire in plain-text does not mean those files are not proprietary. Those files are covered by copyright in the U.S.
Access to the source code is not sufficient for that source code to be FOSS.
You also failed to acknowledge leaked source code and bytecode decompilation, which were a substantial portion of my comment.
The point is that copyleft source code cannot be used to improve proprietary software. That limitation is enforced with copyright.
Proprietary software is closed source. You can't train your NN on it, because you can't read it in the first place.
If someone takes your open source code and incorporates it into their proprietary software, then they are effectively using your work for their private gain. The entire purpose of copyleft is to compel that person to "pay it forward", by publishing their code as copyleft. This is why Stallman is a proponent of copyright law. Without copyright, there is no copyleft.