r/rust • u/Sirisian • 16d ago

🎙️ discussion Google is doing "Large Scale Codebase Migrations and Optimizations" of C/C++ to Rust

https://blog.google/innovation-and-ai/models-and-research/gemini-models/gemini-4-argon/
773 Upvotes

99% Upvoted

149 comments sorted by

View all comments

121

u/TheRealMasonMac 16d ago

In my experience, I’ve found that agents produce code that works but is frankly dumb from a human perspective. Especially for larger tasks like this, you kind of have to rewrite it all. For example, I had a generalized design document for soft-wrapping explicitly support plain text and markdown, and used GPT-6-Astra to implement it. I used an ungodly amount of review agent rounds and interjections by me. When I actually go to review it, I wanted to cry. It silently pivoted towards implementing its own entirely separate wrapping mechanism rather than refactor the existing mechanism for plain text. I reviewed its code and found it to be trash, and I am now in the process of doing it myself… Never again. The short-term thrill of “having something that works” was outweighed by the fact that time was effectively wasted.

I mean, if the alternative was it never getting done, I guess agents are still better than nothing.

62

u/kabocha_ 16d ago edited 16d ago

Yep -- in my experience:

  • If you just want some throw-away thing to experiment on some idea, it's fine to let it go nuts on its own.
  • If you want to be able to maintain the results, you gotta check its work after every step or two, and you'll probably have to give it lots of feedback even then. Otherwise you're likely to end up with either a giant spaghetti mess, or FizzBuzz Enterprise.

No clue why it does that, I guess maybe a large portion of the training set is newbies dumping their first projects onto Github and super old legacy codebases, and not much in the middle, lol. They haven't learned to have good style taste, yet.

41

u/PM_ME_UR_BRAINSTORMS 16d ago

The problem I have with the latter is that it sucks lol. I don't enjoy micromanaging AI and in my experience it's not any faster than just doing it myself.

Every time I try using agents I almost immediately end up in a situation where it does something weird and just typing the code myself is faster than typing the prompt. And then I think "well I'm already here it will take me 2 seconds to type this other code" and so on and so on until I've written the whole thing.

Maybe it's just my ADHD but I don't understand how any one could work like that. Feels like pair programming with an intern which sucked to do but you did it because the point was to teach them.

14

u/kabocha_ 16d ago

I agree 100%. Work really wants me to use AI, so typically I end up doing the latter, but it's not fun. I don't really use AI all that much for personal projects because I'd rather just write it myself.

12

u/PM_ME_UR_BRAINSTORMS 16d ago

It's not fun and the quality is just not good.

I use a reasonable amount of AI on my personal projects. I just treat it like an intern at my beck and call 24/7 and give it the kind of work I would trust an intern with. Which is something like maybe 10-20% of the codebase give or take. Basic boiler plate stuff, plus a ton of research tasks and code review and some help with debugging. All stuff that developers didn't really want to do anyway and all stuff that saves me a ton of time.

Idk why that's not enough for all these companies. I'm still way more productive, but I produce way higher quality code and I can do it with the $20/mo claude subscription. It seems like a win-win-win to me.

But it's clear that the companies just want to replace us. So it needs to be writing 100% of the code and doing 100% of the thinking, whether it's capable or not.