Cool you can just search specifically for potentially unsafe code in Rust. How do you search for unsafe code in Zig? Or do you just have to assume it's everywhere?
The Actix web stuff was the maintainer using unsafe code to increase performance (iirc, it was a long time ago) in what was the most popular rust web frameworks at the time. It has since declined and been supplanted by other projects but the push was mainly a web framework shouldn't need so much unsafe. They eventually ceded the project to another maintainer and went off to work on something else.
For Actix web he was using “unsafe” to increase performance. That doesn’t mean the code written was unsafe… The Rust community was turning to a cult on this topic when perfectly experienced C++ can write code would need the unsafe in Rust when they perfectly know the code isn’t. It’s good for the community to push people to avoid to use unsafe but not to that extend of drama and bullying…
But given the whole "let AI rewrite this for me" stunt nature of this project that was not going to happen because that would require well, actual thinking and a re-design. So now you have Zig disguised as Rust and a line-by-line port because the semantics of idiomatic Rust don't map on the semantics of Zig.
This is the same in COBOL-to-Java ports that have been done in banking and insurance for the past 20 years.
it isn't, because those guys didn't think a naive 1-1 machine translation would give them the benefits of Java, which somehow the people involved in this rust rewriting seem to think they've already gained despite the virtually identical code.
If the whole point genuinely would have been to do a purely mechanical translation they could and should have written a transpiler, which would have had significantly higher correctness guarantees than this given that it'd be deterministic, but of course that would have defeated the PR purpose of this whole thing, which just looks like a marketing for Anthropic frankly
If it were just a marketing stunt you wouldn't have a fraction of a percent of the test suite passing with the remaining bugs being realistically very fixable, and everything written in languages with type systems that give far more guarantees than what COBOL is possible.
You're being extremely negative about this whole endeavour without looking at the evidence that this effort is going far more smoothly than expected, and maps with many people's experience with using LLMs for tasks like these.
no I'm being negative because as I just said, if you want to do a purely syntactic translation you don't even need an LLM, that's called transpilation and we've been doing it programmatically for decades.
This is the kind of thing that looks great to people who can't program, think this is some new superpower unlocked by the mystery magic of LLMs and that is exactly the kind of impression Claude wants to sell.
I'm currently using an LLM in my day job to accelerate such a 1:1translation, and it's certainly "working"/making progress but God I wish I had a formally verified machine translator instead of this probalistic bullshitting LLM.
Don't get me wrong, it's extremely helpful and impressive in what it can do. But I trust it somewhat less than if I had done it myself, and for good reason. The lies I tell myself tend not to take down production. The lies my LLM tells me do however.
Rust can easily call C libraries and vice versa and so can Zig. A more appropriate and designed rewrite would identify the core pieces of the Zig code that were the primary sources of all the big issues. Then, you rewrite that component in Rust and verify that you get the expected improvements. That keeps the codebase stable, it keeps you honest on actually reducing bugs and issues, and other benefits. Then you either just keep it that way or slowly rinse and repeat.
Without doing the analysis of what the core issues were in the first place, the author of Bun can make no claims towards the rewrite. He claims to have fixed flaky tests and improved memory safety. Where is the analysis that shows this? Where is the proof and data? Does he even know where the issues in the Zig codebase were at? I saw a commit where a test had a one second sleep put in place.
Compare this to say the Racket rewrite where a significant portion of the C core was replaced by Chez Scheme and Racket itself. There were several blog posts doing both pre- and post-analysis, and Racket has far less users than Bun.
This rewrite is totally unprofessional and has been poorly and even antagonistically communicated. The author was on this site just days ago telling everyone to relax and that he'd probably throw out this code, and that was even after it had been brought up that this wasn't pre-communicated to users. If I was a dependent in Bun, I would migrate off immediately.
So I push back in the idea that this is the way to do a rewrite like this.
That was until he empirically checked that, contrary to his hypothesis, Claude is _really_ good at mechanical rewrites that preserve functionality and add a type system that prevents the general class of errors that are inherent in Zig's language features, which he has mentioned previously.
I push back against the idea that you need extremely thorough analysis for certain things that end up becoming obvious after working a long time with a codebase. It's clear that Zig doesn't cover certain guarantees that make code robust but Rust does, and this has been documented over and over again because we have examples (with better and worse execution) of the classes of bugs Rust helps and uncover and how a port can go better or worse.
A language with a thorough test suite written in another language with complete coverage is about as good a use case as you can get to support a language rewrite. Ultimately this is about the developer's preference of one language over the other and avoiding simple bugs. What more do you need?
If half of your files in the first pass of a million line rewrite are unsafe then that's completely fine. Do you understand what the tag actually is? It doesn't even mean that the code is actually unsafe, just that the compiler can't guarantee its safety, which can happen for a number of reasons, some benign.
Who rewrites a 700K codebase trying to be idiomatic from the get go ? That's setting yourself up for failure, whether you're a human or a machine.
I just don't like it. I am not ignorant of their intentions, it just does not work well.
Unsafe code is normal. Trying to hide it is unsound. And I stand by that.