The only place it works is dumb boilerplate generation (ie, a smarter replacement for templates), but the real fix for that is just jettisoning languages that beat you to death with boilerplate; its 2026, stop using C++ and Java.
I've extensively tried every LLM model, commercial or not, and for real languages like Rust or Zig, they perform poorly, and for footgun-laden languages like C++ or Java or Python, it just hands you the footgun and helps you aim the thing.