优化state的内存布局和大小

librf/src/def.h

 	};
 	template<class T>
 	using remove_cvref_t = typename remove_cvref<T>::type;
+
+
+	template<class _Ty>
+	constexpr size_t _Align_size()
+	{
+		const size_t _ALIGN_REQ = sizeof(void*) * 2;
+		return std::is_empty_v<_Ty> ? 0 :
+			(sizeof(_Ty) + _ALIGN_REQ - 1) & ~(_ALIGN_REQ - 1);
+	}
 }
 
 #if defined(RESUMEF_DLL_EXPORT)

librf/src/promise.h

 		future_type get_return_object();
 		void cancellation_requested();
 
-		static const size_t _ALIGN_REQ = sizeof(void*) * 2;
-
 		using _Alloc_char = std::allocator<char>;
 		void* operator new(size_t _Size)
 		{
 			std::cout << "promise::new, size=" << _Size << std::endl;
 
 			_Alloc_char _Al;
-			size_t _State_size = ((sizeof(state_type) + _ALIGN_REQ - 1) & ~(_ALIGN_REQ - 1));
+			size_t _State_size = _Align_size<state_type>();
 			char* ptr = _Al.allocate(_Size + _State_size);
-			return ptr + _State_size;
+			return ptr;
 		}
 
 		void operator delete(void* _Ptr, size_t _Size)
 		void yield_value();
 	};
 
-	template<class _Ty = void>
-	constexpr size_t promise_align_size()
-	{
-		return (sizeof(promise_t<_Ty>) + promise_t<_Ty>::_ALIGN_REQ - 1) & ~(promise_t<_Ty>::_ALIGN_REQ - 1);
-	}
 }
 

tutorial/test_async_cb.cpp

 	void* frame_ptr = _coro_frame_ptr();
 	size_t frame_size = _coro_frame_size();
 	std::cout << "test_routine_use_timer" << std::endl;
-	std::cout << "frame point=" << frame_ptr << ", size=" << frame_size << ", promise_size=" << promise_align_size<>() << std::endl;
+	std::cout << "frame point=" << frame_ptr << ", size=" << frame_size << ", promise_size=" << _Align_size<promise_t<>>() << std::endl;
 
 	auto handler = coroutine_handle<promise_t<>>::from_address(frame_ptr);
 	auto st = handler.promise()._state;
 	auto parent = st->get_parent();
 	std::cout << "st=" << st.get() << ", scheduler=" << sch << ", parent=" << parent << std::endl;
 */
-
 	resumef::awaitable_t<int64_t> awaitable;
 	callback_get_long(val, [awaitable](int64_t val)
 	{

tutorial/test_async_routine.cpp

 	void* frame_ptr = _coro_frame_ptr();
 	size_t frame_size = _coro_frame_size();
 	std::cout << "test_routine_use_timer" << std::endl;
-	std::cout << "frame point=" << frame_ptr << ", size=" << frame_size << ", promise_size=" << promise_align_size<>() << std::endl;
+	std::cout << "frame point=" << frame_ptr << ", size=" << frame_size << ", promise_size=" << _Align_size<promise_t<>>() << std::endl;
 
 	auto handler = coroutine_handle<promise_t<>>::from_address(frame_ptr);
 	auto st = handler.promise()._state;

vs_proj/librf.vcxproj

     <ClCompile>
       <WarningLevel>Level3</WarningLevel>
       <Optimization>Disabled</Optimization>
-      <PreprocessorDefinitions>_DEBUG;_CONSOLE;ASIO_STANDALONE;RESUMEF_DEBUG_COUNTER=1;RESUMEF_ENABLE_MULT_SCHEDULER=1;RESUMEF_USE_BOOST_ANY=0;_SILENCE_CXX17_ALLOCATOR_VOID_DEPRECATION_WARNING=1;ASIO_DISABLE_CONCEPTS=1;%(PreprocessorDefinitions)</PreprocessorDefinitions>
+      <PreprocessorDefinitions>_DEBUG;_CONSOLE;ASIO_STANDALONE;RESUMEF_DEBUG_COUNTER=0;RESUMEF_ENABLE_MULT_SCHEDULER=1;RESUMEF_USE_BOOST_ANY=0;_SILENCE_CXX17_ALLOCATOR_VOID_DEPRECATION_WARNING=1;ASIO_DISABLE_CONCEPTS=1;%(PreprocessorDefinitions)</PreprocessorDefinitions>
       <SDLCheck>true</SDLCheck>
       <AdditionalIncludeDirectories>..\librf;..\..\asio\asio\include;..\..\asio-1.10.6\include;%(AdditionalIncludeDirectories)</AdditionalIncludeDirectories>
       <AdditionalOptions>/await</AdditionalOptions>