Doesn't it count as 'clean room' reverse engineering - or alternatively, we could develop an LLM that's trained on the outputs and side-effects of any given function, and learns to reproduce the source code from that.

Or, going back to the original idea, while the source code produced in such a way might be illegal, it's very likely 'clean' enough to train an LLM on it to be able to help in reproducing such an application.

IANAL but if your only source for your LLM is that code, I would assume the code it produces would be at high risk of being counterfeit.

I would guess clean room would still require having someone reading the LLM-decompiled code, write a spec, and have someone else write the code.

But this is definitely a good question, especially given the recent court verdicts. If you can launder open source licensed code, why not proprietary binaries? Although I don't think the situation is the same. I wouldn't expect how you decompile a code matters.