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by josephg 43 days ago
Nope! Zig is like C in this regard. There’s no borrow checker. Managing memory is your responsibility.

It gives you a few more tools than C - like a debug allocator, bounds checked array slices and so on. But it’s not a memory safe language like rust.
2 comments
dnautics 43 days ago
It's not.. but im pretty sure it could be. could probably even take this (WIP) idea and bolt on a formal verifier pretty easily.

https://github.com/ityonemo/clr

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josephg 43 days ago
It'd take more than that to match rust's borrow checker. Rust's borrow checker tracks lifetimes, and sometimes needs annotations in code to help it understand what you're actually trying to do. I suppose you could work around that by adding lifetime annotations in zig comments. Then you've have a language that's a lot like rust, but without an ecosystem of borrowck-safe libraries. And with worse ergonomics (rust knows when it can Drop). And rust can put noalias everywhere in emitted code. And you'd probably have worse error messages than the rust compiler emits.

Its an interesting idea. But if you want static memory safety in a low level systems language, its probably much easier to just use rust.

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dnautics 43 days ago
> I suppose you could work around that by adding lifetime annotations in zig comments.

you can make a no-op function that gets compiled out but survives AIR

> rust knows when it can Drop.

and its possible to cause problems if you aren't aware where rust picks to dropp.

> And rust can put noalias everywhere in emitted code.

zig has noalias and it should be posssible to do alias tracking as a refinement.

> But if you want static memory safety in a low level systems language, its probably much easier to just use rust.

don't use that attitude to suck oxygen out of the air. rust comes with its own baggage, so "just using rust because its the only choice" keeps you in a local minimum.

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josephg 43 days ago
> and its possible to cause problems if you aren't aware where rust picks to drop.

Can you give some examples? I've never ran into problems due to this.

> don't use that attitude to suck oxygen out of the air. rust comes with its own baggage

Yeah, that's a totally fair argument. One nice aspect of the approach you're proposing is it'd give you the opportunity to explore more of the borrow checker design space. I'm convinced there's a giant forest of different ways we could do compile time memory safety. Rust has gone down one particular road in that forest. But there's probably loads of other options that nobody has tried yet. Some of them will probably be better than rust - but nobody has thought them through yet.

I wish you luck in your project! If you land somewhere interesting, I hope you write it up.

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dnautics 42 days ago
> Can you give some examples? I've never ran into problems due to this.

If it's doing a drop in the hot loop that may be an unexpected performance regression that could be carefully lifted.

thank you. Unfortunately in the last few weeks i've been too busy with my startup to put as much work into it. We'll see =D

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josephg 42 days ago
> If it's doing a drop in the hot loop that may be an unexpected performance regression that could be carefully lifted.

Yeah, I've heard of people being surprised that when they make massive collections of Box'ed entries, then get surprised that it takes a long time to Drop the whole thing. But this would be the same in C or Zig too. Malloc and free are really complex functions. Reducing heap allocations is an essential tool for optimisation.

The solution to this "unexpected performance regression" in rust is the same as it is in C, C++ and Zig: Stop heap allocating so much. Use primitive types, SSO types (SmartString and friends in rust) or memory arenas. Drop isn't the problem.

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pjmlp 42 days ago
Those tools exit in C tooling as well, now that many ignore them is another matter.

MSVC has a debug allocator since at least Visual Studio 5.

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