[OskarS]

It's interesting, because it's a "cultural" thing like the author discusses, it's a very good point. Sure, you can do unsafe integer arithmetic in Rust. And you can do safe integer arithmetic with overflow in C/C++. But in both cases, do you? Probably you don't in either case.

"Culturally", C/C++ has opted for "unsafe-but-high-perf" everywhere, and Rust has "safe-but-slightly-lower-perf" everywhere, and you have to go out of your way to do it differently. Similarly with Zig and memory allocators: sure, you can do "dynamically dispatched stateful allocators that you pass to every function that allocates" in C, but do you? No, you probably don't, you probably just use malloc().

On the other hand: the author's point that the "culture of safety" and the borrow checker in Rust frees your hand to try some things in Rust which you might not in C/C++, and that leads to higher perf. I think that's very true in many cases.

Again, the answer is more or less "basically no, all these languages are as fast as each other", but the interesting nuance is in what is natural to do as an experienced programmer in them.

[Xirdus]

C++ isn't always "unsafe-but-high-perf". Move semantics are a good example. The spec goes to great lengths to ensure safety in a huge number of scenarios, at the cost of performance. Mostly shows up in two ways: one, unnecessary destructor calls on moved out objects, and two, allowing throwing exceptions in move constructors which prevents most optimizations that would be enabled by having move constructors in the first place (there was an article here recently on this topic).

Another one is std::shared_ptr. It always uses atomic operations for reference counting and there's no way to disable that behavior or any alternative to use when you don't need thread safety. On the other hand, Rust has both non-atomic Rc and atomic Arc.

[josefx]

> one, unnecessary destructor calls on moved out objects

That issue predates move semantics by ages. The language always had very simple object life times, if you create Foo foo; it will call foo.~Foo() for you, even if you called ~Foo() before. Anything with more complex lifetimes either uses new or placement new behind the scenes.

> Another one is std::shared_ptr.

From what I understand shared_ptr doesn't care that much about performance because anyone using it to manage individual allocations already decided to take performance behind the shed to be shot, so they focused more on making it flexible.

[Xirdus]

C++11 totally could have started skipping destructors for moved out values only. They chose not to, and part of the reason was safety.

I don't agree with you about shared_ptr (it's very common to use it for a small number of large/collective allocations), but even if what you say is true, it's still a part of C++ that focuses on safety and ignores performance.

Bottom line - C++ isn't always "unsafe-but-high-perf".

[the8472]

The rust standard library does make targeted use of unchecked arithmetic when the containing type can ensure that that overflow never happens and benchmarks have shown that it benefits performance. E.g. in various iterator implementations. Which means the unsafe code has to be written and encapsulated once, users can now use safe for loops and still get that performance benefit.