crubit VS c2rust

See also:

Thomas Neumann's current proposal for memory safe C++ using dependency tracking:

- https://www.open-std.org/jtc1/sc22/wg21/docs/papers/2023/p27...

Google's proposal for memory safety using Rust-like lifetime analysis:

- https://discourse.llvm.org/t/rfc-lifetime-annotations-for-c/...

- https://github.com/google/crubit/tree/main/lifetime_analysis

For the people who are curious: crubit is an attempt to develop the way to seamlessly integrate C++ and Rust.

Please see the experimentation and proposals at https://github.com/google/crubit/blob/main/docs/lifetime_annotations_cpp.md and https://github.com/google/crubit/blob/main/docs/lifetimes_static_analysis.md

autocxx is good, though crubit is aiming for direct bidirectional interop

The areas you mentioned (CLI, web services, low level systems programming) are not mutually exclusive. Doing a good job on one doesn't mean something else is affected.

The folks who worked on the most popular command line argument parser (https://docs.rs/clap/latest/clap/#example) made a positive contribution that didn't detract from any other use case.

Similarly, the folks working on improving Rust for web services will also make it better for systems programming. In a blog post published today (https://blog.rust-lang.org/inside-rust/2022/07/27/keyword-ge...), they discuss keyword generics, a feature that will be equally helpful for `async` code and `const` functions evaluated at compile time.

There is already some interoperability with C++ (http://cxx.rs) and ongoing research into automating this interoperability (https://github.com/google/autocxx, https://github.com/google/crubit). Feels like there's enough effort

This language was started by folks at Google. (Although it's interesting that they're publishing it under a separate github org, which suggests ambitions beyond Google's needs.) Google has a huge, performance-sensitive C++ codebase. At Google, major product teams' backends are typically written in C++, as well as common infrastructure like D (disk server), Colossus (distributed filesystem), Spanner (distributed SQL database), and Borg (cluster management). More than a few people would love for it all to be be written in Rust instead, but migration would be challenging, to say the least. I'm told people are looking into it—see Crubit for example. But AFAIK, no one's decided yet whether Google will stay with C++ for all these things, migrate some to Rust, migrate some to Carbon, and/or do something else entirely.

It's currently unclear if Rust can interop with C++ with high fidelity. For example https://docs.rs/moveit/latest/moveit/ and https://github.com/google/crubit/blob/main/rs_bindings_from_... provide functionality to use non-trivially relocatable C++ types from Rust.

A recent practical example of the former: the fish shell re-wrote incrementally from C++ to Rust, and is almost finished https://github.com/fish-shell/fish-shell/discussions/10123

An example of the latter: c2rust, which is a work in progress but is very impressive https://github.com/immunant/c2rust

It currently translates into unsafe Rust, but the strategy is to separate the "compile C to unsafe Rust" steps and the "compile unsafe Rust to safe Rust" steps. As I see it, as it makes the overall task simpler, allows for more user freedom, and makes the latter potentially useful even for non-transpiled code. https://immunant.com/blog/2023/03/lifting/

But not all transpilers are between languages where at least one of them is designed to be transpiled. For example, c2rust can transpile, as the name suggests, C to (ugly, unsafe) Rust. A while ago there was a Java -> C compiler in GCC (GCJ), but it's pretty out of date now.

I do not know about your specific issue but you may be interested by https://github.com/immunant/c2rust

You should also consider using C2Rust (they're even working on C -> safe Rust translation)

> The date at the bottom of the article is 2022-06-13. Has there been further progress?

The article links to their github repo:

https://github.com/immunant/c2rust

There's commits in the last hour, so at least some signal of life.

This is arguably already the state of things.

Rust might get compiled down through MIR, down through LLVM IR, down to assembly or wasm... which then might be JIT or AOT (re)compiled into other bytecodes... which might perhaps be decompiled back up to C... and C might be retranslated back to horrific unsafe-spamming Rust by the likes of https://c2rust.com/. We've come full circle!

The main issue is that retranslating high level languages into other high level languages isn't something that there's actually a lot of demand for, especially commercially, especially given the N x M translation matrix going on. So a lot of the projects "stabilize" (get abandoned). And automatically translating between the idioms of those languages gets even nastier in terms of matrix bloat.

Well, you've got stuff like MSIL and JVM bytecodes which are higher level, and preserve more type information, and can be compiled to / decompiled from while still preserving more structure, but they still form competing incompatible ecosystems.

That's the wrong direction. What's needed are intelligent converters which convert less-strict languages to more-strict ones.

Non-intelligent converters just make a mess. Here's c2rust.[1]

Classic C++ to modern C++, plus a compiler flag to lock out all the old unsafe stuff, would be an achievement.

[1] https://c2rust.com/

Well, technically, it's not hard to build such data structures. If you are willing to liberally use raw pointers, UnsafeCell, MaybeUninit and ManuallyDrop, then you can more-or-less write C-equivalent code in unsafe Rust. (there are even transpilers from C to Rust)

/uj This transpiles from C to unsafe Rust using an existing tool, then strips the unsafe keyword from the generated function signatures