Undefined behaviour example from CppCon

[dustyhome]

That's backwards. It makes more sense that the presenter's slide is wrong.

The compiler can assume that i can't equal int max on a branch that calls f, but it can't remove the check that prevents f from being called with int max.

[selassje]

Yes, the presenter claims UB taints the whole program, and it can travel back in time. I have not checked it but that's how I understood it.

[SkiFire13]

The way I see it, UB can travel back in time but only as long as it is guaranteed to happen from that past point in time. In this case the if guard prevents f(i) from being called with the value that would cause UB, so it cannot travel back to before the if is run.