If you have a hot loop where it matters, you can put an assert outside the loop which lets llvm remove the bounds checks. Or use unsafe { get_unchecked() } to remove the bounds check entirely.
Exactly, yes. I know it's possible, of course it's possible, its just not trivial like it is in C++.
Most developers I have met don't know how to use a profiler, so not sure any of this discussion matters at all anyway, but I feel like it's important to note when the default in Rust is safe, whereas the default in C++ is fast (and more or less unsafe)
Eh, that argument cuts both ways. Lots of the defaults in C++ are bad. Like, most people don’t know how compiling all your code in a single code unit will improve performance. Or how to do it. In rust it’s a single flag in cargo.toml which is widely talked about. Rust has a much better, faster standard library than C++. Any code which makes heavy use of - for example - sorting in C++ and rust will favour rust because it uses a better algorithm by default.
Rust had the opportunity to iterate on C++’s default choices and improve on them in many cases. I’m not convinced that naive C++ is particularly efficient.
(That said, lots of rust beginners make heavy use of Box and clone() and write inefficient programs that way. It’s hard to actually measure average, beginner code.)
