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Bun's experimental Rust rewrite hits 99.8% test compatibility on Linux x64 glibc

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Re: Bun's experimental Rust rewrite hits 99.8% test compatibility on Linux x64 glibc

#431

Post by stingraycharles »

leecommamichael wrote: post #324
ksec wrote: post #26

I think a lot of people taking this at face value , a lot of this was possible because of the beyond standard extensive and comprehensive test suit previously built.

If this is a "beyond standard" test suite, (so much so that it _uniquely_ makes this work possible compared to other projects,) then how is Bun also uniquely unstable compared to other Zig programs (and so deserving of rewrite?) If the blame lies partially with the test suite, what does this imply (if anything) about the Rust port?

Because tests validate behavior, not undefined behavior.

The thesis is that Rust makes undefined behavior less likely.

Re: Bun's experimental Rust rewrite hits 99.8% test compatibility on Linux x64 glibc

#432

Post by himata4113 »

jwpapi wrote: post #314

Completely unbased, but I don’t want to have to do anything with bun anymore. It’s just a gut feeling, but I don’t trust them and support them. They fork Zig to utilize LLM rewrites and build something the Zig team clearly disregarded (non-deterministic compiling) And now like a whiny baby they LLM rewrite to Rust. There is a very real chance that Zig design philosophy got them to the point where they are now by enfo…

I consider zig the "whiny baby" approach to be honest.

Re: Bun's experimental Rust rewrite hits 99.8% test compatibility on Linux x64 glibc

#433

Post by johncolanduoni »

baranul wrote: post #354
johncolanduoni wrote: post #216

Earlier quoted context omitted.

I don’t think the Zig project adopting a strict ‘no LLM’ policy affects the LLM vendors at all. How many developers are working on the Zig project itself that will (maybe) now not buy a Claude subscription? I can buy that this is a marketing stunt, but nobody at the top cares if a relatively small open source project doesn’t allow AI contributions.

I don't know about that. Zig's bdfl got significant mainstream press attention for his anti-LLM stance. Definitely enough attention for various LLM vendors to notice.

Based on their actions, I don’t think the LLM vendors take anti-AI sentiment very seriously. If anything they court it, though I think it’s more likely they’re just high on their own supply. I doubt the Zig statement had any effect on the thoughts of the people who actually sign contracts with Anthropic, who are mostly not engineers.

The marketing opportunity here is in promoting Claude Code, not giving a smackdown to Andrew Kelley (who vanishingly few people who throw around millions of dollars on AI contracts have heard of).

Re: Bun's experimental Rust rewrite hits 99.8% test compatibility on Linux x64 glibc

#434

Post by thrwaway55 »

perching_aix wrote: post #413
thrwaway55 wrote: post #411

Earlier quoted context omitted.

I disagree. This is the same sort of marketing strategy as Mythos.Wow it out performed so much we have to tell you in the future. If he wasn't aligned financially with the outcome I'd agree but he's not

So do you picture them locking up the Rust port behind closed doors as well, or what's the game gonna be? Cause it reads like it's kinda all public already.

Absolutely not, I think they prioritize it because it's internal. I to expect to see a stronger marketing push on its ability to do language translations because there is honestly value in that. Question is when they have compute but it's less crisis marketing then their security stuff so I'd see it at a lower priority. I just don't think it's as honest as the parent post posits

Re: Bun's experimental Rust rewrite hits 99.8% test compatibility on Linux x64 glibc

#435

Post by FjordWarden »

Validark wrote: post #428
FjordWarden wrote: post #419

I love Bun & Zig and this feels a bit like my parent are getting a divorce. I thought it was a bit strange that Bun did not sponsor the Zig foundation while others much smaller companies have.

Are you kidding? IIRC Oven gave $5k/month to Zig for years. And btw that was before they got acquired for billions, when they had no income at all.

Alright my bad I did not find any info about this, but still they are no longer mentioned as a sponsor.

Re: Bun's experimental Rust rewrite hits 99.8% test compatibility on Linux x64 glibc

#436

Post by fg137 »

kennykartman wrote: post #296
suck-my-spez wrote: post #222

Serious question… Who’s going to want to run a vibe coded runtime in production? I don’t see how this is a good look for Bun?

One should care about tests more than how code was coded. If I had a codebase with lots of tests and asked someone else to rewrite it to another language passing the same test suite, I honestly wouldn't expect a great quality job. I say this because it happened 3 times in the company I work for: we conducted experiments by tasking different companies to rewrite the same code in another language. All of them passed (m…

I have seen, many times, code that has lots of tests but don't work.

Why?

Some of the patterns that I saw:

* The code is only called from tests but never called in production

* Tests are not testing the actual application logic, or the logic that matters. In some cases, the tests have nothing to do with the application code at all, because it does not even run any application code.

* Tests repeat the same logic as in application (tautology). All the time.

* Application code is actually incorrect. But tests just end up using the wrong expected value to make tests pass, disregarding what should happen.

That's using the latest models.

To make things better, apparently people never bothered to go through the manual workflow at least once to verify the behavior.

Good luck just relying on tests.

Re: Bun's experimental Rust rewrite hits 99.8% test compatibility on Linux x64 glibc

#437

Post by dwattttt »

bsder wrote: post #386
gobdovan wrote: post #362

Earlier quoted context omitted.

As an amateur in the space: I download on Mac, run `ngspice`, "Error: Can't open display: :0". I look in the code - hardcoded X11-era assumptions. Not exactly modern affordances... Then I try to understand and extract the actual formulas, and there isn't a clean formula layer anywhere. All is procedural, e.g. in `b4v6temp.c` formulas are tangled with branching, caching, model-state mutation. Extracting the computatio…

> As an amateur in the space Why are you not using this through KiCad? That's what I would expect an amateur to do; especially since they handle the UX that you are complaining about. And you are complaining about tangled code but that code is almost certainly hyper-optimized since performance actually mattered a LOT to people running spice simulations. ng-spice (and Spice3 and Spice2) were not written for programmin…

> Why are you not using this through KiCad? That's what I would expect an amateur to do; especially since they handle the UX that you are complaining about.

They sound like an amateur at circuit design, not software engineering (which is how I'd describe myself too).

Re: Bun's experimental Rust rewrite hits 99.8% test compatibility on Linux x64 glibc

#438

Post by hitekker »

Validark wrote: post #428
FjordWarden wrote: post #419

I love Bun & Zig and this feels a bit like my parent are getting a divorce. I thought it was a bit strange that Bun did not sponsor the Zig foundation while others much smaller companies have.

Are you kidding? IIRC Oven gave $5k/month to Zig for years. And btw that was before they got acquired for billions, when they had no income at all.

Yeah, that tracks according to the numbers.

https://ziglang.org/news/300k-from-mitchellh/

https://ziglang.org/news/2024-financials/#income

https://ziglang.org/news/2025-financials/#income

I had a bit of trouble finding it myself but Claude proved a better Googler than I

Re: Bun's experimental Rust rewrite hits 99.8% test compatibility on Linux x64 glibc

#439

Post by nextaccountic »

nhatcher wrote: post #211
Jarred wrote: post #105

Earlier quoted context omitted.

cargo check reported over 16,000 compiler errors when I wrote that message. It could not print a version number or run JavaScript. I didn’t expect it to work this quickly and I also didn’t expect the performance to be as competitive. There’ll be a blog post with more details.

That's a post I am eagerly waiting to read. Basically we are seeing now an "inverse Hofstadter's Law" where doing something with an LLM takes less time thanexpected even when you take into account this law. I am a Rust developper myself but I really love Zig and Bun. I am just overly curious of all this.

> Basically we are seeing now an "inverse Hofstadter's Law" where doing something with an LLM takes less time thanexpected even when you take into account this law.

Even LLMs themselves can't accurately estimate this (though this may be out of distribution stuff)

Re: Bun's experimental Rust rewrite hits 99.8% test compatibility on Linux x64 glibc

#440

Post by hitekker »

Validark wrote: post #285

I'm a full time Zig developer, and I see this as an absolute win. I know Jarred has said in the past he feels Zig makes him more productive, but I also think it's fair to say Bun was programmed in a way that's quite cavalier towards buffer overruns. I think Jarred and the Oven team will have significantly better luck with Rust. Some commenters have remarked they only heard of Zig because of Bun, therefore this is bad…

Not sure why you're getting downvoted; I think you're close to right. They were successful with one technology and had a great exit. They may also be successful with another technology post-acquisition.

Lets see the fruit of their decision.

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