One of the motivating cases for this proposal is that gcc/clang, without fwrapv, will both implement wrapping on most architectures (since that is what the processor implemements) and silently remove manual overflow checks for overflow because it is "impossible" under a stupid interpretation of what UB means. Similarly, those compilers will remove manual checks for null pointers if there is a prior dereference to a pointer on the theory that dereferences of null pointers are "impossible" even when they happen.