C and C++ do well because there is most literature and code out there to help them reason about it. C is helpful because it has little hidden runtime for them to trip over.

that being said, those languages obviously have limits in applicability looking at the entire spectrum of software. JS, python and others still have useful domains.

i dont think newer languages as rust are better for LLMs as they might be for new programmers. for new programmers they offer extra features but for an LLM this is added potential to make mistakes. Also a lot of newer languages are less stable so you can realise their current implementations might not be fully trained on by the models or even be after their cutoff date..