The go compiler (already) inserts yields in a bunch of places that aren't IO or explicit synchronization points. And it's hard to predict the exact locations th

The go compiler (already) inserts yields in a bunch of places that aren't IO or explicit synchronization points. And it's hard to predict the exact locations they'll be because much of it happens after some optimizations have been made. It is very much already attempting to look preemptive, which is why the authors didn't use the term coroutine for the language feature -- it's an implementation detail. This proposal is about fixing some of the edge cases where the current implementation doesn't do what the interface is supposed to. It outlines another, simpler approach which just has the compiler add more yields, but apparently the performance impact of that is too high. But it's just a question of perf & implementation complexity, not semantics.