You're right. I didn't enumerate every way UB can make a program go wrong. I'm sure I don't even know every way that can happen. But "UB doesn't happen at run t

You're right. I didn't enumerate every way UB can make a program go wrong. I'm sure I don't even know every way that can happen. But "UB doesn't happen at run time" is an assumption that lots of "optimizations" are based on.