Rust doesn't prevent programs from having logic errors.
If LLMs produce code riddled with bugs in one language it will do in other languages as well. Rust isn't going to save you.
If LLMs produce code riddled with bugs in one language it will do in other languages as well. Rust isn't going to save you.
Sure, but it prevents memory safety issues, which C doesn't. As for logic bugs, what does prevent them? That's a bigger question but I'd suggest it's:
1. The ability to model your problem in a way that can be "checked". This is usually done via type systems, and Rust has an arguably good type system for this.
2. Tests that allow you to model your problem in terms of assertions. Rust has decent testing tooling but it's not amazing, and I think this is actually a strike against Rust to a degree. That said, proptest, fuzzing, debug assertions, etc, are all present and available for Rust developers.
There are other options like using external modeling tools like TLA+ but those are decoupled from your language, all you can ever do is prove that your algorithm as specified is correct, not the code you wrote - type systems are a better tool to some degree in that way.
I think that if you were to ask an LLM to write very correct code then give two languages, one with a powerful, express type system and testing utilities, and one without those, then the LLM would be far more likely to produce buggy code in the system without those features.
There are static tools available for C as well. What you get from Rust mostly is that the check is part of the syntax of the language as well and escaping from it is very visible. You get safety, but you give up flexibility and speed.
Really? Never from limitations of the ability to express your mental model in a way that's formally verifiable? What a strong claim to make.
> There are static tools available for C as well.
For checking the semantics of the code itself? And why discount the fact that a tool being native means it's easier to adopt?
Like everything around Rust, this has been discussed ad nauseam.
Preventing memory safety bugs has a meaningful impact in reducing CVEs, even if it has no impact on logic bugs. (Which: I think you could argue the flexible and expressive type system helps with. But for the sake of this argument, let's say it provides no benefits.)
If the only concern is "can an LLM write code in this language without memory errors" then there's plenty of reasons to choose a language other than Rust.
First, Rust has lots of checks that C and assembly don't, and AI benefits from those checks. Then, a post about those checks are related to memory safety, not logic errors. Then, a post about whether that's a helpful comment. Finally, me pointing out that checks regarding types and memory errors aren't unique to Rust and there's tons of languages that could benefit.
Since you want to bring it back to the original article, here's a quote from the author:
Is C the ideal language for vibe coding? I think I could mount an argument for why it is not, but surely Rust is even less ideal. To say nothing of Haskell, or OCaml, or even Python. All of these languages, after all, are for people to read, and only incidentally for machines to execute.
Fil-C gets you close in the case of C, but we can ignore it because, of course, F* has significantly more checks than Rust, and AI benefits from those checks. Choosing Rust would be as ridiculous as choosing C if that was your motivation.
But if you don't find the need for those checks in order to consider Rust, why not C or even assembly instead?
If you don't find importance in those checks, you wouldn't choose Fil-C anyway. But, of course, it remains that if do find those checks to be important, you're going to use a serious programming language like F* anyway.
There is really no place for Fil-C, Rust, etc. They are in this odd place where they have too many checks to matter when you don't care about checks, but not enough checks when you do care about checks. Well, at least you could make a case for Fil-C if you are inheriting an existing C codebase and need to start concerning yourself with checks in that codebase which previously didn't have concern for them. Then maybe a half-assed solution is better than nothing. But Rust serves no purpose whatsoever.
These trade-offs are wholly unnecessary if the LLM writes the software in Rust, assuming that in principle the LLM is able to do so.
Nobody ever claimed that. The claims are:
1. Rust drastically reduces the chance of memory errors. (Or eliminates them if you avoid unsafe code.)
2. Rust reduces the chance of other logic errors.
Rust doesn't have to eliminate logic errors to be a better choice than C or assembly. Significantly reducing their likelihood is enough.
Although we did recently get pretty good evidence of those claims for humans and it would be very surprising if the situation were completely reversed for LLMs (i.e. humans write Rust more reliably but LLMs write C more reliably).
https://security.googleblog.com/2025/11/rust-in-android-move...
I'm not aware of any studies pointing in the opposite direction.
> it would be very surprising if the situation were completely reversed for LLMs
Lifetimes must be well-defined in safe Rust, which requires a deep degree of formal reasoning. The kind of complex problem analysis where it is known that LLMs produce worse results in than humans. Specifically in the context of security vulnerabilities, LLMs produce marginally less but significantly more severe issues in memory safe languages[1]. Still though, we might say LLMs will produce safer code with safe Rust, on the basis that 100,000 vibe coded lines will probably never compile.
> LLMs produce worse results in than humans
We aren't talking about whether LLMs are better than humans.
Also we're obviously talking about Rust code that compiles. Code that doesn't compile is 100% secure!
> would you say "have you done a scientific study on the average journey times across the year and for different locations to know that it was actually bad"?
In response to a similarly suspiciously faulty inductive claim? Yeah, absolutely.
> We aren't talking about whether LLMs are better than humans.
The point I'm making here is specifically in response to the idea that it would "be surprising" if LLMs produced substantially worse code in Rust than they did in C. The paper I posted is merely a touch point to demonstrate substantial deviation in results in an adjacent context. Rust has lower surface area to make certain classes of vulns under certain conditions, but that's not isomorphic with the kind of behavior LLMs exhibit. We don't have:
- Guarantees LLMs will restrict themselves to operating in safe Rust
- Guarantees these specific vulnerabilities are statistically significant in comparative LLM output
- The vulnerability severity will be lower in Rust
Where I think you might be misunderstanding me is that this isn't a statement of empirical epistemological negativism. I'm underlining that this context is way too complex to be attempting prediction. I think it should be studied, and I hope that it's the case LLMs can write good, high quality safe Rust reliably. But specifically advocating for it on gut assumptions? No. We are advocating for safety here.
Because of how chaotic this context is, we can't reasonably assume anything here without explicit data to back it up. It's no better than trying to predict the weather based on your gut. Hence, why I asked for specific data to back the claim up. Even safe Rust isn't safe from security vulnerabilities stemming from architectural inadequacies and panics. It very well may be the case that in reasonably comparable contexts, LLMs produce security vulnerabilities in real Rust codebases at the same rate they create similar vulnerabilities in C. It might also be the case that they produce low severity issues in C at a similar statistical rate as high severity issues in Rust. For instance, buffer overflows manifesting in 30% of sample C codebase resulting in unexploitable segfaults, vs architectural deficiencies in a safe Rust codebase, manifesting in 30% of cases, that allow exfiltration of everything in your databases without RCE. Under these conditions, I don't think it's reasonable to say Rust is a better choice.
Again, it's not a critique in some epistemological negativist sense. It's a critique that you are underestimating how chaotic this context actually is, and the knock-on effects of that. Nothing should surprise you.
But most of them don't have a nice strong type system like Rust. I have vibe coded some OCaml and that seems to work pretty well but I wouldn't want to use OCaml for other reasons.
Modern sewers sometimes back up, so might as well just releive yourself in a bucket and dump it into your sidewalk.
Modern food preservation doesn't prevent all spoilage so you might as well just go back to hoping that meat hasn't been sitting in the sun for too many days.
You can't get a gutter ball if you put up the rails in a bowling lane. Rust's memory safety is the rails here.
You might get different "bad code" from AI, but if it can self-validate that some code it spits out has memory management issues at compile time, it helps the development. Same as with a human.
Sure you can. It's difficult, and takes skill, but it can be done.
https://security.googleblog.com/2025/11/rust-in-android-move...
That team claims that not having to deal with memory bugs saved them time. That time can be spent on other things (like fixing logic errors)