Language vision regarding safety guarantees

ia0:

And that's what expected of you today. But Rust is a language supposed to let people write logic bugs without them turning into UB.

I don't understand what your proposal changes in this respect. I'd still do the same thing if every function had to have a Robustness section in its documentation. I'd write: Robustness: yes, 100% for all my functions.

I wouldn't trust a library that says Robustness: no, this code may contain bugs. It doesn't seem like a good advertisement.