To be clear: I mean UB in the C standard. The cases where there is UB are mostly spelled out explicitly, so we can go through all the cases and define behavior. There might be cases where there is implicit UB, i.e. something is accidentally not specified, but this has always been fixed when noticed. It is not possible to remove all cases of UB though, but the plan is to add a memory safe mode where there is no UB similar to Rust.