Design Alternatives for Type and Resource Safe C++

The paper you're talking about is I think P2687, design alternatives for type and resource safe C++. That's the one that you co-authored with Gabby. So it's a really interesting paper. But question is, can we actually eliminate all the UB by placing constraints on the language? And then still be left with a subset of language that is expressive enough and useful enough to do real world programming.