A major issue with removing UB exploitation is that you've now created C, but each compiler implements a different C. It becomes harder to port code, and you end up with bugs that can be harder to catch, especially if don't consider what you're doing an error, as now you can't even use the sanitizers.

What my team has been looking at to help developers that have these issues is providing low overhead ways to give defined, but likely to crash, behavior for these cases. This helps protects against UB without creating C. An example would be variable auto-init, which intentionally doesn't support zero init, as that is likely to hide bugs: https://reviews.llvm.org/D54604

I'm fine with fully defining some things that are currently UB or IB. I'm also fine with keeping things as UB. What I'm not fine with is creating this implicit C that programmers think they know what it is, but it's not actually defined anywhere, and not everyone working on the compiler is on the same page about.