flexstr VS miri

https://crates.io/crates/flexstr

Not sure I follow the question exactly and tbh it was like a year ago and I forget the specifics. You are welcome to look at the code, however:

https://github.com/nu11ptr/flexstr/blob/master/flexstr/src/b...

templates: https://github.com/nu11ptr/flexstr/tree/str_generics/generate

BStr Example CStr Example OsStr Example

Github | Crates.io | Docs.rs

[Github](https://github.com/nu11ptr/flexstr) | [Crates.io](https://crates.io/crates/flexstr) | [Docs.rs](https://docs.rs/flexstr/latest/flexstr/) | [Benchmarks](https://github.com/nu11ptr/flexstr/blob/master/benchmarks/README.md)

The comparison isn't with rust today, but the long term differences between the languages. Rust has a straightforward path to rectifying the standardization issue and enough community momentum to succeed.

For example, Rust has an in-progress specification, here's the (currently empty) repo: https://github.com/rust-lang/spec. There's also MIR, a de-sugared internal representation that's sufficiently well specified to build formal models of (see https://github.com/rust-lang/a-mir-formality and https://github.com/rust-lang/miri), as well as the ferrocene spec (https://spec.ferrocene.dev/general.html) that's suitable for certification authorities (if not actually useful) and of course the rust reference/RFCs that are actually usable by people.

Plus, the fact that everyone in the rust community has standardized on one compiler and one package manager (for better or worse) means that the language team has a much better insight into specification breakages than the ISO process of languages like C and C++.

I can start writing stuff today and be confident that any changes will be minor if necessary when the language catches up.

The one link for those who think that Rewrite it all in Rust will, well, settle any debates: https://github.com/rust-lang/miri/

>While we are many missing language features away from this being the case, the noalias case is also magic descended upon box itself, with no user code ever having access to it.

I'm not sure why the author thinks there's magic behind Box. Box is not a special case of `noalias`. Run this snippet with miri and you'll see the same issue: https://play.rust-lang.org/?version=stable&mode=debug&editio...

`Box` _does_ have an expectation that its inner pointer is not aliased to another Box (even if used for readonly operations). See: https://github.com/rust-lang/miri/issues/1800#issuecomment-8...)

Miri [0] is an interpreter for the mid-level intermediate representation (MIR) generated by the Rust compiler. MIR is input for more processing steps of the compiler. However miri also runs MIR directly. This means miri is a VM. Of course it's not a bytecode VM, because MIR is not a bytecode AFAIK. I still think that miri is a interesting example.

And why does miri exist?

It is a lot slower. However it can check for some undefined behavior.

[0]: https://github.com/rust-lang/miri

Provenance is a dynamic property of pointer values. The actual underlying rules that a program must follow, even when using raw pointers and `unsafe`, are written in terms of provenance. Miri (https://github.com/rust-lang/miri) represents provenance as an actual value stored alongside each pointer's address, so it can check for violations of these rules.

Lifetimes are a static approximation of provenance. They are erased after being validated by the borrow checker, and do not exist in Miri or have any impact on what transformations the optimizer may perform. In other words, the provenance rules allow a superset of what the borrow checker allows.

There has been discussion of doing this with MIRI, which would be easier than all of rustc.

This issue has been fixed: https://github.com/rust-lang/miri/issues/2964

Actually, I've done more advanced tests with MIRI (see https://github.com/rust-lang/miri/issues/2920 for example) which allowed me to fix some issues. I've also made the code compatible with loom, but I didn't found the time yet to write and execute loom tests. That's on the TODO-list, and I need to track it with an issue too.