wait_for_any.cpp

#include "winrt/base.h"
#include <Windows.h>

using namespace winrt;
using namespace Windows::Foundation;
using namespace std::chrono;

template <typename...Async>
void wait_for_any(Async&&... async)
{
    auto signal = std::make_shared<handle>(CreateEvent(nullptr, true, false, nullptr));

    (async.Completed([signal](auto&&...)
    {
        SetEvent(signal->get());
    }), ...);

    WaitForSingleObject(signal->get(), INFINITE);
}

IAsyncAction A() { co_await 3s; puts("A"); }
IAsyncAction B() { co_await 2s; puts("B"); }
IAsyncAction C() { co_await 1s; puts("C"); }

int main()
{
    init_apartment();
    wait_for_any(A(), B(), C());
    puts("At least one completed");
    getchar();
}