#include <coroutine>
#include <exception>
#include <initializer_list>
#include <cstdio>

#define TRACK() printf("%s\n", __PRETTY_FUNCTION__)

struct awaitable // std::suspend_always carbon copy
{
    awaitable() { TRACK(); }
    ~awaitable() { TRACK(); }
    constexpr bool await_ready() const noexcept { TRACK(); return false; }
    constexpr void await_suspend(std::coroutine_handle<>) const noexcept { TRACK(); }
    constexpr void await_resume() const noexcept { TRACK(); }
};

struct [[nodiscard]] fiber
{
    struct promise_type // coroutine controller
    {
        promise_type() { TRACK(); }
        ~promise_type() { TRACK(); }
        fiber get_return_object() { TRACK(); return handle_type::from_promise(*this); }
        awaitable initial_suspend() noexcept { TRACK(); return {}; }
        awaitable final_suspend() noexcept { TRACK(); return {}; }
        void return_void() { TRACK(); }
        void unhandled_exception() { TRACK(); std::terminate();}
    };
    using handle_type = std::coroutine_handle<promise_type>;
    handle_type handle = nullptr;
    fiber(handle_type h): handle(h) { TRACK(); }
    ~fiber() { TRACK(); if (handle) handle.destroy();}
};

fiber make_fiber()
{
    TRACK();
    for (auto i: {0, 1, 2, 3, 4})
    {
        printf("%i ", i);
        co_await awaitable{};
    }
}

int main()
{
    TRACK();
    auto t = make_fiber();
    while (!t.handle.done())
        t.handle.resume();
}