When zero cost abstractions aren't zero cost
The 'zero cost' attitude is one of C++ problems. Zero cost abstractions are never really entirely zero cost. You still pay, often in something that you didn't bother to measure, which (in C++) is usually compile time or programmer productivity or programmer cognitive cost or compiler complexity.There's a reason a lot of the complaints about C++ mention bloat or the difficulty of practically choosing a safe subset (you could use a subset, but you're very likely dependent on coworkers, existing codebases and library authors which may not share your subset). A lot of people added 'zero cost' stuff, and all of that has a cost.For example, lets say Rust's newtype pattern worked perfectly everywhere, and all of the author's examples run fine as u8 with no runtime cost. There would likely still be a small cognitive cost to learn this, a small cost to unwrap the types (for other programmers reading the code), and a tiny cost in compile time. Typedefs are worth it, and it's all very reasonable to pay this!But there's still a cost, and when people never believe there's a cost a language ends up like C++.