[tialaramex]

> they are part of the standard library

They're part of Rust's core library. So they're available even when the full standard library isn't. Indeed core::option::Option is in effect a Lang Item, library components which are required to exist by the Rust language itself, as somebody pointed out to me on HN previously (technically Some and None are Lang Items, but well, they need to be the same type, so while an imaginary Rust implementation could name it Maybe or something instead of Option, that type needs to exist or the language can't happen at all)

C++ freestanding a) is barely supported, it's completely normal for a compiler vendor, e.g. Microsoft, to just decide they will not offer this at all and b) full of holes, so e.g. std::optional isn't provided in the freestanding library.

As a result, there isn't this same ubiquity in C++ for low level work. The language's built in types are garbage, and most of the standard library isn't available. Historically you had no choice, it's this rubbish or nothing, but Rust and to some extent Zig make that no longer true for a gradually increasing range of targets. Some C++ people have woken up and tried to improve freestanding because "We're terrible but there's no other choice" stops being a good sales pitch once your users have other Options. So I expect C++ 26 freestanding will be more useful and perhaps even better supported, for whatever that's worth.