[gcp]

Most of us write new, complex data-structures, that aren't part of the stdlib or a crate, like once a year, at most. Those are hard in Rust if they involve circular pointers. They're hard in C/C++ too, but in a different way (easier to write the code, harder to be sure it's correct).

The idea that Rust would be no better than C/C++ because of the latter parts doesn't make much sense. This kind of work is unusual for most programming. To say that other programming work is easy does not seem to bear out in practice.

And as has been becoming clear in this thread, if you're inventing new data structures, the odds are you overlooked an already existing better alternative.

[alphaalpha101]

It doesn't matter that it's 'kind of unusual', even though I contend that it isn't. Even if, for the sake of argument, we assume that it is, that doesn't change my point.

My point is that the whole point of Rust is supposedly that it

>is a systems programming language that runs blazingly fast, prevents segfaults, and guarantees thread safety.

except that when you look at any of the examples of code that really would benefit from the compiler's help, the compiler just throws its hands in the air and goes 'it's all up to you now'.

The problem is that Rust doesn't let you make a single assumption and let the compiler prove the safety of the code using that assumption. It just has a valve that you can hit that removes all guarantees.

If you could say 'this code is safe assuming that this FFI function doesn't exhibit undefined behaviour, please check that for me' or write a proof that says 'this actually is safe, because this pointer can only ever point into this valid memory or this valid memory, and this is why' then the compiler would still be useful.

Whether 'this work' (which is not just creating data structures, but anything that the compiler doesn't understand, which is much broader than just creating data structures) is unusual or not, IMO the whole appeal of Rust is that it makes doing that work easy. But it doesn't.

Rust just doesn't seem worth it, doesn't seem worth rewriting whole ecosystems of code. It doesn't give any actual safety.

[Rusky]

> examples of code that really would benefit from the compiler's help

This seems to be the point of disagreement here, and I think evidence clearly shows that you are wrong. Sure, Rust doesn't help you when writing the implementation of e.g. circular data structures. But what it does do is provide, far beyond C or C++, the tools for the author of that data structure to enforce that it's used correctly.

And as mentioned upthread, most memory/concurrency (especially concurrency) bugs are not in the implementations of these structures, but in their use. So Rust is a fantastic win here, empirically speaking. Look at the rate of memory safety bugs in Rust programs vs C++ programs- Ripgrep vs grep, Servo/Quantum vs Firefox, etc.