Comment by jakobnissen

This is completely infeasible. A C compiler makes so many assumptions that UB does not occur that every program, even well functioning ones, would emit walls of warnings. Also, these warnings can't be silenced. Consider the integer division case: Should the warning be emitted every time division by zero is encountered at runtime? In that case, C would be much, much slower. Or should the compiler emit the warning whenever it can't prove at compile time that the divisor is not zero? In that case, you would get tonnes of situations where you can't fix the issue because you can't prove to the compiler it's not zero. Division by zero is a easy case. It gets much harder to emit warnings for aliasing assumptions, for example.