Earlier quoted context omitted.
Precisely. This is perhaps the strangest part of the original post: C++ has the same performance advantages as Rust! It has them not because it's more safe (although it is, in some regards), but because it allows programmers to express behaviors that the compiler can reason about statically.
One cannot imagine C++ failing to emulate Rust's borrow checker by the end of the decade, even if compiler support is required. Has C++ ever failed to snarf a feature?
But part of the impetus for Carbon is that WG21 (the C++ Standards Committee) rejected proposals that C++ should focus on better performance and safety. So maybe performance is no longer important either. What's left?
Where they've taken things which might appear on the surface to be modelled on a safer Rust feature, usually the committee insists they be made unsafe. For example suppose I call a Rust function which might return a char or might not, it returns Option and if I'm an idiot and I try to treat that as a char, it doesn't type check because it isn't one, I need to say what I'm going to do when it isn't or else that won't compile.
You can write that in modern C++... except it can automatically try to take the char (which isn't there) out of the empty optional structure and that's Undefined Behaviour. So whereas the Rust prevents programmers from making easy mistakes, the C++ turns those into unexploded bombs throughout your code.