Right. When you are talking about the compiler and the abstract machine, perhaps some sentences could be clearer about that (e.g. the sentences I latched onto - which I admit is my fault for skim reading).

Responding to whether C is "low-level" I like this comment: http://lambda-the-ultimate.org/node/5534#comment-95721 And processors have undefined behaviour so should we say assembly is not "low-level"? e.g. "Grep through the ARM architecture reference manual for 'UNPREDICTABLE' (helpfully typeset in all caps), for example…" - pcwalton

Thanks heaps for your article which was a good read, and it led me to the funnier side of undefined behaviour: https://raphlinus.github.io/programming/rust/2018/08/17/unde... and https://lkml.org/lkml/2018/6/5/769