Well, sure, you just need a sufficiently smart compiler :) > You can still avoid overflows even on a pure library implementation without compiler helps by swit

Well, sure, you just need a sufficiently smart compiler :) > You can still avoid overflows even on a pure library implementation without compiler helps by switching to the main thread continuation Yes in fact that's what we had to do with fibers (see for example folly::runInMainContext()) but that means that all code that may be called from a fiber needs to be fiber-aware, which is not ideal.