I've tried to do the same with Codex (gpt-5.1-codex-max) and Gemini (2.5 pro), both failed spectacularly

pshirshov on Hacker News

In the thread “JOPA: Java compiler in C++, Jikes modernized to Java 6 with Claude”

Helped: Using Sonnet 4.5 for Java 6 tasks.

Got in the way: Codex and Gemini failed spectacularly; Opus 4.5 hits limits.