Rust has documentation which describes how it's supposed to behave, which is a far cry from everything being undefined behavior. It also has a formal specificat

Rust has documentation which describes how it's supposed to behave, which is a far cry from everything being undefined behavior. It also has a formal specification of a subset of the language. It's not like the C/C++ specs are particularly precise. I think people tend to have a mental model of specs as equivalent to formal semantics, which they very much are not.