> It's a hard question because any coherent semantics you come up with breaks optimizations that are obviously correct™. This is difficult to convey in toy examples, because in toy examples, there's clearly enough information present that the optimizer could do the right thing™ if it were smart enough.

I don't buy this (particularly your first sentence). I need to see it to believe it.™ I'm not saying it's not the case, just that it's kind of a tough sell when the illustration fails basic scrutiny.

But if it's actually true, then that's a reason to stop using toy examples in explanations, not a justification for plowing ahead with obviously wrong toy arguments.

Imagine if laws worked this way? "As you can see here, you actually ran a red light." "But the light is literally green?!" "It's difficult to show in this picture, but it is red. Trust me bro, we wouldn't catch obvious criminals if we only addressed the cases where it was obviously red." Uhm, what?