alt Hacker NewsC++ doesn't have a smart ponter for 'i will not need this for longer than something else' - shared pointer gets the overhead of reference counting. Rust makes borrows easy - taking and returning a unique_ptr is conceptually the same thing but the syntax makes it tedious. Borrows don't cover the case of I'll store it but whole program analisys would show I won't store it as long as the owner (i'm not a rust expert but I think my understanding is right here)
both languages don't have a good way to handle circular references should you need them (again my rust isn't strong but I think that is right). You are correct to say avoid that - but sometimes you need them.
It does, it's called a pointer. You're literally not allowed to dereference a pointer once the pointee has ceased to exist, so by using them you're making the promise you'll ensure this is satisfied.
C++ is not limited to unique_ptr, the language (unlike Rust) allows you to define your own semantics of what a value is. You can then work in terms of copying or moving values, which makes lifetime management trivial as they are scope-bound.