unsafe-code-guidelines VS min-sized-rust

Useful context on the Rust side is this issue [1]. It sounds like some of the author's concerns are addressed already.

[1]: https://github.com/rust-lang/unsafe-code-guidelines/issues/4...

Is this captured by one of the known soundness conflicts? If not then should consider adding it to the list.

There are some competing proposals for different memory models. Stacked borrows is the current proposal, but there are more work in the approproate WG.

Thank you /u/RalfJung for bringing formal methods to Rust, both through models like Stacked Borrows, by developing miri, and by working on unsafe-code-guidelines which aims to specify exactly what is and isn't allowed in unsafe code (surprisingly, it's an open question as 2023!)

You could imagine some way to make this safe for example automatically convert &'short &'long mut T to &'short &'short T, but it's non-trivial to prove they are safe at all, not to mention ensuring this is correctly implemented in the compiler. If you're interested there's also a discussion on whether the opposite (& & T to & &mut T) is sound here.

Agreed! MIRI is so good, it still feels like magic to me. It also comforts me that the Rust team takes improving unsafe semantics seriously, with the past Unsafe Code Guidelines WG and today's operational semantics team (t-opsem).

I think there are some aspects of this rule that are still undecided. See for example:

- https://github.com/rust-lang/unsafe-code-guidelines/issues/8...

- https://github.com/rust-lang/miri/issues/2732

C is much better specified than unsafe Rust. Some things are just not worked out yet in Rust. This may sometimes even bite very experienced devs, such as this issue with Box's aliasing semantics, which tripped up the author of left-right.

This is a good guide on building small Rust binaries: https://github.com/johnthagen/min-sized-rust

This talks about going to extreme lengths on making the smallest Rust binary possible, 400 bytes when it was written, https://darkcoding.net/software/a-very-small-rust-binary-ind...

The thing is, you lose a lot of nice features when you do this, like panic unwinding, debug symbols, stdlib… for kernel and some embedded development it’s definitely important, but for most use cases, does it matter?

Oh it was 137, haha. I will link you to this older comment of mine: https://news.ycombinator.com/item?id=29408906

See also https://github.com/johnthagen/min-sized-rust

Are you sure? If so then this is awesome news, but I'm a bit confused; the commit in that min-sized-rust repo adding `build-std` to the README was merged in August 2021: https://github.com/johnthagen/min-sized-rust/pull/30

Are you saying that at that point the feature still hadn't "landed in Rust nightly" until recently? If so then what's the difference between a feature just being available in Rust nightly, vs having "landed"?

Rust binaries are by default nowhere close to 500MB. If they are not small enough for you, you can try https://github.com/johnthagen/min-sized-rust. By avoiding the formatting machinery and using `panic_immediate_abort` you can get about the size of C binaries.

A useful reference: https://github.com/johnthagen/min-sized-rust

That must be without stripping. Also there are ways to reduce binary size. See e.g. [min-sized-rust](https://github.com/johnthagen/min-sized-rust). I've gotten stripped binaries of small cli utils less than 400KiB without doing anything special, less than 150 KiB by customizing profile settings and compressing with upx, and less than 30 KiB by replacing the std with the libc as the link shows. Haven't tried with fltk though...

This is not quite what you're asking, but it does also address the underlying concern: https://github.com/johnthagen/min-sized-rust