[oconnor663]

I think catching fire here refers to the general "this is UB and all bets are off" situation. For example, if you're data racing against an int on x86-64 Linux, you might reason that the `mov` instruction on that platform can't possibly product torn reads. And you'd be right as far as that goes. But the C/C++/Rust compiler still considers those data races UB and may still do horrible things like just deleting big chunks of your code if it manages to prove that that's what you've done.