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.
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.
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.
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.