Oh, so you are on "that's what I want!" camp. But I am pretty sure you are in minority, or at the very least economic minority. Slowdown implied by this semantics is large, and easily costs millions of dollars.
> while I'd probably argue that it's actually OK for the compiler to treat cases differently based on the apparent intent of the programmer.
This is actually what I am looking for, i.e. answer to "then what do you mean?". Standard should define how to divine the apparent intent of the programmer, so that compilers can do divination consistently. So far, proposals have been lacking in detailed instruction of how to do this divination.
Bugs based on optimizations that compilers make based on assumptions enabled by undefined behavior (like the null check issue from 2009 in the Linux kernel) actually don't cost very much. They get a disproportionate amount of scrutiny relative to their importance.
> while I'd probably argue that it's actually OK for the compiler to treat cases differently based on the apparent intent of the programmer.
This is actually what I am looking for, i.e. answer to "then what do you mean?". Standard should define how to divine the apparent intent of the programmer, so that compilers can do divination consistently. So far, proposals have been lacking in detailed instruction of how to do this divination.