Why complain to the compiler writers? As you say, people want the fastest compilers for their language, so compilers will prioritize that over other concerns. U

Why complain to the compiler writers? As you say, people want the fastest compilers for their language, so compilers will prioritize that over other concerns. Users may rant and complain, but they won't use a slower compiler. If you really want less UB, switch to a different language or change the language! Complain to the standards committee, have them define behavior that is currently undefined, or impose restrictions on allowable behaviors. Compilers are always going to optimize to the extent that the language standard allows, so change the standard.