We should build compilers that insert these checks for us (if they cannot statically determine them unnecessary). The ability to omit these checks doesn't IMHO justify undefined behaviour.

Well, good news is that you have optional modes in most compilers that do this.

You would not want to force these by default, nobody wants it. You can not statically determine them unnecessary in for the vast majority of code, even stuff as simple as `print(read(a) + read(b))`.