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

void track(std::source_location l = std::source_location::current()) noexcept
{
    fprintf(stderr, "%s:%u %s\n", l.file_name(), l.line(), l.function_name());
}

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

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