Cpp2Rust: Translates C++ to safe Rust automatically

> Notable unsupported constructs include: union, volatile, goto, exceptions, bitfields, placement new, user-defined copy/move constructors, dynamic_cast, const_cast, base classes with fields or non-virtual methods, multiple inheritance, and multi-threaded code.

If I can autoport my C++ to Rust, and the port is confirmed identical, and the Rust is confirmed safe, can't I use that to reason about the safety of my C++? Is safe C++ just a matter of proving it has a safe Rust equivalent?

If the concern is memory safety, I'd invite comparison with migration to the scpptool-enforced memory-safe subset of C++ [1]. If your C++ code is "idiomatic modern" C++, then the changes required to conform to the safe subset (in an idiomatic way) are often modest, and as demonstrated in the link, often something an LLM can handle for you. Since the safe subset does not impose a universal restriction on mutable aliasing the way Rust does, it doesn't require wrapping everything in `RefCell<>`s or anything like that (unless the objects in question are being shared between threads).

If your C++ code is more "legacy" than "modern", the migration is generally still straightforward, but will often involve additional run-time overhead, like it does with this cpp2rust, but to a lesser degree I think. Objects allocated on the stack can (safely) remain allocated on the stack even when they are the target of pointers. And still, no `RefCell<>` equivalents are required for objects that aren't shared between threads.

[1] https://github.com/duneroadrunner/scpptool/blob/master/READM...

Interesting, but unpractical. As I know there is no way to perform automatic translation from one programming language to another without producing code which looks terrible in the destination language.

In this particular example I see no real safety benefits. If the source program is buggy, the result translated program willcrash at runtime, but if it's (mostly) bug-free and UB-free, such translation gives no benefits.

Why does the example not show an example of unsafe C++?

The original paper quoth:

> our reference-counted translation model, where every variable is pessimistically wrapped inside a Rc<RefCell<T>> type, checks that would usually execute at compile-time are shifted to run time, degrading performance.

This was featured at PLDI 26 [1].

I'm not yet convinced that the issue of C's unsafety is better solved by translating it to Rust rather than using Fil-C [2].

https://pldi26.sigplan.org/program/program-pldi-2026/

https://fil-c.org/

Yeah the readme definitely needs some non-trivial examples. How does this handle raw pointers? Operator overloading? Inheritance?

Why didn't they target Zig?

codex "/goal port this codebase from c++ to rust"