This seems to omit the main point of it, though? That the compiler turns a function into a state machine that can restart from any of its suspension points. I guess that's the "state" variable, but what I'm talking about is what it contains and the partially compiler-generated code that deals with it.<p>C++ async is unfortunately a "bring your own runtime" sort of model (for now), but it does handle the part that would be incredibly tedious by hand, building above mentioned state machine.
You are confusing it with coroutines. This is just a plain library feature that the compiler doesn’t necessarily have special support for.
That's the co_await/co_yield/co_routine stuff, which this isn't talking about--this is talking about the std::future-et-al logic, which predates C++ coroutines by almost a decade.