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Comment by kybernetyk | Hacker News Reader

> I struggle to believe that C or C++ can be written safely

It can. You just need to avoid those performance optimizations that were en vogue in the 90s/early00s. Luckily modern computers (and the more modern C++ standards) can handle value semantics just fine and you don't need to put pointers into vectors anymore because directly putting the data there would be too costly, etc.

If you only use the new (C++11 up) smart pointers (avoiding new/delete) you've essentially achieved 80% of Rust's safety model. Add rigorous application of const correctness and you're good to go. Rust still adds a few important things but until its eco system is matured (and there is real tooling) modern C++ is a pretty good alternative.

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As an analogy, you can write safe code in assembler as well if you and your team are incredibly disciplined and only interact with libraries written with a similar amount of discipline. The appeal of alternatives is you can write safe code with a fraction of the discipline and mental effort required.

There is no extra “discipline“ or “mental effort” required to write safe C++. Don’t use new/delete/free/malloc and don’t use operator&. Of course, you can say that we might as well remove them from the language entirely, but I really don’t think it takes extra effort not to use them.

There are countless ways of causing undefined behaviour in C++ (not including memory management mistakes) as well as platform specific behaviour that you don't see in other languages. It's a very complex language to master compared to alternatives.

See eg http://blog.regehr.org/archives/140

C++14:

  auto p = std::make_unique<int>(5);
  auto q = std::move(p);
  std::cout << *p << std::endl;

Segfault using the “safe” C++ features. I'm a fan of modern C++, but it's not safe (in a Rust sense) even if you stick to C++11/C++14 features.

For comparison, the same thing in Rust:

  fn main() {
      let p = Box::new(5);
      let q = p;
      println!("{}", p);
  }

gives, upon compiling:

    error: use of moved value: `p` [E0382]
    println!("{}", p);
                   ^
    note: in this expansion of format_args!
    note: in this expansion of print! (defined in <std macros>)
    note: in this expansion of println! (defined in <std macros>)
    help: run `rustc --explain E0382` to see a detailed explanation
    note: `p` moved here because it has type `Box<i32>`, which is moved
    by default
    let q = p;
        ^
    help: if you would like to borrow the value instead, use a `ref`
    binding as shown:
    let ref q = p;
    error: aborting due to previous error

Running `rustc --explain E0382` or going to https://doc.rust-lang.org/nightly/error-index.html#E0382 gives you an extended error message as well.

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