Yet another Hacker News

When Modernization Breaks Working Code: A Study of LLMs on Legacy PHP

12 points tambourine_man 1 day ago 6 comments

StevenWaterman 52 minutes ago | parent

Models:

- Claude Sonnet

- Gemini 2.5 Flash

- Gemini 2.5 Pro

- GPT-5 Codex

- Llama 3.3 70B

It's inconvenient how quickly things are improving, makes potentially-interesting results like this dubiously relevant

plorkyeran 40 minutes ago | parent

> We study a common intermediate setting: a developer pastes one complete file into a chat assistant [5], which sees the file’s internal structure but not its callers or dependencies. We evaluate the first answer, not an agent’s result after iterating on errors.

Very unsurprising results given this methodology. The agentic approach where models are allowed to iterate on changes is a very big part of what has made LLM coding tools actually useful.

yodon 30 minutes ago | parent

> We study a common intermediate setting: a developer pastes one complete file into a chat assistant [5], which sees the file’s internal structure but not its callers or dependencies.

Ack! Do people actually try to develop software this way?

plorkyeran 7 minutes ago | parent

Not any more, but it was common before Claude Code came along (~18 months ago). Based on the model versions used it may have still been the most common thing when the paper was started.

refactor_master 5 minutes ago | parent

I do it from time to time when I’ve run out of tokens at the end of the month. But even then I’ve created a script to pack multiple code files and their dependencies into a single txt, with a tree overview.

And of course you never change the test suite in the process… That would be bad developer practice, LLM or not.

Gemini 3.1 Pro can easily work with this effectively, if not a bit slower than an agent.

AdrianB1 30 minutes ago | parent

One year ago I was very skeptical about such attempts. Today, it would be my first choice as LLMs evolved a lot and the result of carefully using a LLM for this task can be very, very good.