What problem does c2Rust solve exactly? Isn't it just gonna produce "garbage" rust. Calling c directly is already possible in rust.
It makes it easier to get your project on the front page of HN as you can claim it is written in Rust.
Emitting Safer Rust with C2Rust
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Re: Emitting Safer Rust with C2Rust
#12C2rust is really cool, but if you're familiar with writing rust and implement even a trivial C function in there it produces something absolutely terrifying. I really enjoy rust and pray I don't find myself working in a code base someone just ran c2rust against.
Isn’t the point to generate semantically equivalent Rust code from C, so that you can just get it re-compiling under Rust, and then from there you have a working base from which to start rewriting into safer Rust?
Re: Emitting Safer Rust with C2Rust
#13What problem does c2Rust solve exactly? Isn't it just gonna produce "garbage" rust. Calling c directly is already possible in rust.
It moves the project directly into rust land and tooling, which hopefully makes it easier to convert it without needing to set up multi langage tooling and a moving barrier / interface between the two langages.
Re: Emitting Safer Rust with C2Rust
#14Do no know this particular tool but some automated language to language transpilers I saw produce the code one would not be able to comprehend never mind edit if the need comes.
The goal of C2rust is not to provide a usable code base per se, it’s to provide a convenient base for conversion: once the project is in unsafe rust it can be managed entirely via rust tooling and is hopefully a lot easier to finish up than if you keep having to redefine bindings as you move code from C to Rust.
C2rust is a springboard, if you move C2rust-Ed code to production you’re doing it very wrong.
Re: Emitting Safer Rust with C2Rust
#15C2rust is really cool, but if you're familiar with writing rust and implement even a trivial C function in there it produces something absolutely terrifying. I really enjoy rust and pray I don't find myself working in a code base someone just ran c2rust against.
Isn’t the point to generate semantically equivalent Rust code from C, so that you can just get it re-compiling under Rust, and then from there you have a working base from which to start rewriting into safer Rust?
Yes, it’s literally spelled out in TFA:
> this provides a starting point for manual refactoring into idiomatic and safe Rust
Re: Emitting Safer Rust with C2Rust
#16What problem does c2Rust solve exactly? Isn't it just gonna produce "garbage" rust. Calling c directly is already possible in rust.
The post does address this and shows their attempt to produce higher quality Rust. I've also seen it used to move off of a C toolchain and onto a pure Rust toolchain by porting C code to Rust.
Re: Emitting Safer Rust with C2Rust
#17I'm very excited at the possibilities for C2Rust! Dynamic analysis to fill in the gaps of static analysis makes a lot of sense. I've wanted something similar for inferring TypeScript types via runtime analysis (would not be surprised if it exists already).
I could see a really compelling use case in cross-compilation where you compile your C code to Rust, then use a Rust toolchain to cross compile. Or avoiding interop as well.
Re: Emitting Safer Rust with C2Rust
#18DARPA is funding this. Good.
They haven't reached inter-procedural static analysis yet, which means they can't solve the big problem: how big is an array? Most of the troubles in C come from that. Whoever creates the array knows how big it is. Everybody else is guessing.
A bit of machine learning might help here. If you see
void dosomethingwitharray(int arr[], size_t n) {}
fn dosomethingwitharray(arr: &[i64]) {}
assert_eq!(arr.len(), n);
The process can be assisted by putting asserts in the original C, as checks on the C and hints to the conversion process. That's probably the cleanest way to provide human assistance.
I've wanted this for conversion of OpenJPEG code to Rust. That's a tangle of code doing wavelet transforms, with long blocks of touchy subscripting and arithmetic, plus encoders and decoders for an overly complex binary format containing offsets and lengths. Someone recently ran it through c2rust. The unsafe Rust code works. It's compatible with the original C - it segfaults for the same test cases which cause the C code to segfault. This is why a naive transpiler isn't too helpful.
(The date at the bottom of the article is 2022-06-13. Has there been further progress?)
Re: Emitting Safer Rust with C2Rust
#19DARPA is funding this. Good. They haven't reached inter-procedural static analysis yet, which means they can't solve the big problem: how big is an array? Most of the troubles in C come from that. Whoever creates the array knows how big it is. Everybody else is guessing. A bit of machine learning might help here. If you see void dosomethingwitharray(int arr[], size_t n) {} a good conjecture is that n is the length of…
> 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.
Re: Emitting Safer Rust with C2Rust
#20Has anyone put this to serious use? I played around with it at some point when it was fairly new and at that time I was able to transpile the C into Rust just fine, but that didn't help me much. The idea was to be able to use the Rust toolchain to better understand the code, but the resulting Rust code was even less understandable, and also much harder to refactor. In this case I wasn't attempting a rewrite per se, just trying to understand a C codebase plagued with memory safety issues. Quickly gave up on this avenue at that point and just started carefully refactoring the C to make the bugs easier to shake out.
Would love to see a technical write up of someone outside Immunant using this on a real world codebase for whatever purpose.