The evidence in the form of CVEs suggests that we don't get it right. > You mean the vector::operator[] is an example of fast-and-potentially-UB ? I don't see

The evidence in the form of CVEs suggests that we don't get it right. > You mean the vector::operator[] is an example of fast-and-potentially-UB ? I don't see any UB if the constraints are met (keeping the index within valid range). I don't understand this line of reasoning when it's plain that the contraints are not met. Routinely. It happens all the time. Again, see the CVEs.