The boost coroutines mentioned are not the same thing as the C++20 ones. Boost captures the stack, that's what the register shuffling is for. C++ is a compiler

The boost coroutines mentioned are not the same thing as the C++20 ones. Boost captures the stack, that's what the register shuffling is for. C++ is a compiler transform that moves some state onto the heap, but probably not the whole stack, and builds a switch dispatch style thing to transform the control flow. This is why C++ comes with co_* annotations and coroutines don't.