Zig is not entirely unsafe. It provides quite a few compile time checks and primitives to catch memory leaks or prevent them altogether.
This is mostly a concern with the Rust stdlib, though. And it's in principle fixable, by writing new varieties of those stdlib functions that take raw-pointer or &UnsafeCell<...> arguments, and delegating the "safe" varieties to those.
The pointer must be properly aligned.
It must be non-null.
It must be “dereferenceable”: a pointer is dereferenceable if the memory range of the given size starting at the pointer is entirely contained within the bounds of that allocated object. Note that in Rust, every (stack-allocated) variable is considered a separate allocated object.
The pointer must point to a valid value of type T.
When creating a mutable reference, then while this reference exists, the memory it points to must not get accessed (read or written) through any other pointer or reference not derived from this reference.
When creating a shared reference, then while this reference exists, the memory it points to must not get mutated (except inside UnsafeCell).
[0]: https://doc.rust-lang.org/stable/core/ptr/index.html#pointer...
As a concrete example, I previously used Vec in unsafe code that dealt with uninitialized memory. This should be fine because Vec is basically a raw pointer and two integers. But later they changed the docs to say that this was undefined behavior (essentially, Vec reserves the right to “produce” a reference whenever it wants, even if you avoid calling methods that would do that). So my code that previously followed the rules now appeared to violate them.
The method is available[0] in nightly Rust
pub const unsafe fn as_uninit_ref<'a>(self) -> Option<&'a MaybeUninit<T>>
where
T: Sized,
{
// SAFETY: the caller must guarantee that `self` meets all the
// requirements for a reference.
if self.is_null() { None } else { Some(unsafe { &*(self as *const MaybeUninit<T>) }) }
}
Even if it weren't, this exaggeration is a complete theater. You aren't supposed to use unsafe Rust unless you really have to. I have been using Rust since 2020 and I've used it once, for 3 lines of code. The entirety of all Zig codebases is unsafe. That's fine if you are fine with unsafe code, but this myth is dishonest, and I take great issue with using a language where the founder is the primary source of the dishonesty - because what else is being swept under the rug?
Q: You didn't do X, so Zig will never be able to track X
A: Maybe. Only way to know for sure is to fork this (or, hopefully, a 'real' successor) and fail. However, consider that "trivially" it should be possible to externally annotate every zig file with lifetime/type annotations identical to that of Rust and run "exactly the same" analysis as Rust and get the same memory safety as Rust.
it appears the clr author anticipated you: you didnt fork it, try, and fail, so you have ceded the authority to credibly make your speculative complaint
> Zig isn't meaningfully different in expressivity
it is meaningfully different in expressivity at the AIR level. AIR looks nothing like c, c++, zig, or rust.
That's a caveat. Not an expectation.
Plus that's not how proof works. Neither Zig nor Zig+Clr have really proven they are safe, ergo they are unsafe or possibly safe (respectively).
Does the incompletely POC do all the parts, or doesn't it? That is no criticism against the project itself, striving to improve memory safety in any language is an honorable goal. The cinch is that an incomplete POC doesn't prove things one way or another, the POC needs to be completed (or at least completed far enough to prove your point). It either matches or exceeds Rust memory safety, or it only vastly improves Zig memory safety. Both are great outcomes, for what it's worth.
It shouldn't have been shown as an example of how Zig is just as/more safe than Rust if it is not. Mispresenting the project tears it down, not questioning its use an an example. Just like misrepresenting Zig's safety (and Rust's unsafety) tears Zig down.
Are you satisfied like "proof is left as an exercise for the reader" in a math textbook? Or is it like "I have proved this but it's too large to fit in the margins"?
It seems author couldn't be bothered to complete it since there's (minor) missing features in the zig compiler that need to be satisfied first to make it worthwhile?
In the first example the proof would be available elsewhere. In the second example, no. My answer is "just the facts as they exist today."
A mathematical proof holds no inherent utility. The thing it proves is what is useful. What I find useful is not suffering memory safety woes. Can I run a tool, any tool, today that will give me the same assurances that the Rust compiler (and/or Miri) does? Conjecture about the future is pointless because someone could equally go and write some static analysis tool like clr for Rust to fix all the bad parts, or fix the compiler, or the parts of clr that aren't finished might be impossible (we don't know, nobody has tried), or the heat death of the universe could come early. All still irrelevant, because I'm a user and I care exclusively about what I can currently do.
If I say "Moon is made of millennia old cheese", the burden of proof isn't on you to go create a rocket, fly to the moon, sample it and come with conclusions, but on me, making a difficult to verify statement.
That's not a substantiated claim. Miri also runs very slowly.
> You aren't supposed to use unsafe Rust unless you really have to. I have been using Rust since 2020 and I've used it once, for 3 lines of code.
Cool, glad you haven't needed it. If you're ever writing interpreters or interfacing with external code, you'll need it.
> The entirety of all Zig codebases is unsafe
Zig is not 100% memory safe but it has compile-time safety features for vast majority of problems developers get themselves into with C/C++. Meanwhile, Rust's safety overhead has real trade-offs in terms of developer productivity, computational performance, compiler performance and binary size.
The article we are commenting on substantiates it with, several, actual examples.
> interpreters
In what world do interpreters require unsafe code? A naive interpreter that recursively descends an AST doesn't need it, and a bytecode interpreter doesn't need it either. You'll probably need it if you want to make a fast GC, but that does not mean your entire codebase has to be unsafe.
> interfacing with external code
This is one reason unsafe exists, yes. You are supposed to hide the unsafe parts behind a safe interface. For example, Rust unavoidably has to deal with external code to do I/O - yet, the exposed std::fs interface is safe. This is a well established doctrine in the Rust community, and at least one prominent project has received hot hell for ignoring it.
And, again, the portions of code that are unsafe in a Rust codebase - even when required - are supposed to be minimal, well contained, and well tested. Running a suite of tests to check a small amount of code under Miri is not prohibitive at all. If someone is going to insist on using unsafe across their codebase then, yes, they are far better served by using a language that is unsafe to begin with.
I have done embedded Rust, and even there I have largely avoided unsafe code (the 3 lines I was forced to write happened to be for embedded).
> Rust's safety overhead has real trade-offs [...]
I never claimed otherwise. Those trade-offs have a purpose: fewer degrees of freedom result in higher degrees of certainty. Even Rust has too many degrees of freedom[1], but we don't sweep that under the rug, deflect it, or outright lie about the situation.
The Rust zeitgeist largely agrees your opinion (or rather: Andrew's opinion) of unsafe Rust, in a very oblique way. It's shit, we don't like using it. It is certainly not an accurate summary of Rust as a whole.
Leveraging unsafe Rust against Rust as a whole is a dishonest line of thinking and I'm not going to engage with it further.
From what I've seen, clang has all of these and more for C++. If your metric is "tooling to help you catch UB", C++ is significantly superior to Zig.
I'd actually give the edge to C++ over Zig, because of smart pointers (not that I'm implying smart pointers are anywhere near sufficient).
In this context of, if you are using Zig for its safety via tooling, there is a much more mature candidate C++.
The article, in its review of the Zig language, goes after its marketing history and broken promises (calling Andrew's statements fallacious and worse) for attempting to portray itself as safer than unsafe Rust, the distortions around UB (undefined behavior), etc... As a consequence of the demonstrably valid test results and being tired of unreliability, the author stopped using Zig. It should also be mentioned, that v1 Zig is nowhere in sight, so likely many years more to wait.