> But gcc is part of it's training data so of course it spit out an autocomplete of a working compiler /s

Why the sarcasm tag? It is almost certainly trained on several compiler codebases, plus probably dozens of small "toy" C compilers created as hobby / school projects.

It's an interesting benchmark not because the LLM did something novel, but because it evidently stayed focused and maintained consistency long enough for a project of this complexity.