What happens if you make an annotation mistake? Could the compiler generated code then have a security vulnerability, just like when you use undefined behaviour and the compiler is then allowed to optimize safety checks away?
No- the idea is that if you make an annotation mistake, you will get an error, because the program will not match its annotations.
Lifetimes are not like an `unreachable` UB operation. Instead they are just a description of cross-function information, about what both the caller and callee are allowed to assume.
You could technically (both in Rust and under this proposal) do the same checks without them, if you had access to the entire program at once. However, this would be more expensive, and probably give you less-localized error messages (a lot like C++ template errors, for similar reasons).
