pass one tag for all remaining parameter types

make tag a variadic template and use it to pass multiple types in one go
to readIntoFunction.

This fixes an Internal Compiler Error on VS 2015.2:
- fixes #7
- closes #8

include/LuaContext.hpp

@@ -708,7 +708,7 @@ class LuaContext {
     /*                     MISC                       */
     /**************************************************/
     // type used as a tag
-    template<typename T>
+    template<typename... Tn>
     struct tag {};
 
     // tag for "the registry"
@@ -1596,29 +1596,29 @@ class LuaContext {
      * This functions reads multiple values starting at "index" and passes them to the callback
      */
     template<typename TRetValue, typename TCallback>
-    static auto readIntoFunction(lua_State* /*state*/, tag<TRetValue>, TCallback&& callback, int /*index*/)
+    static auto readIntoFunction(lua_State* /*state*/, tag<TRetValue>, TCallback&& callback, int /*index*/, tag<>)
         -> TRetValue
     {
         return callback();
     }
     template<typename TRetValue, typename TCallback, typename TFirstType, typename... TTypes>
-    static auto readIntoFunction(lua_State* state, tag<TRetValue> retValueTag, TCallback&& callback, int index, tag<TFirstType>, tag<TTypes>... othersTags)
+    static auto readIntoFunction(lua_State* state, tag<TRetValue> retValueTag, TCallback&& callback, int index, tag<TFirstType, TTypes...>)
         -> typename std::enable_if<IsOptional<TFirstType>::value, TRetValue>::type
     {
         if (index >= 0) {
             Binder<TCallback, const TFirstType&> binder{ callback, {} };
-            return readIntoFunction(state, retValueTag, binder, index + 1, othersTags...);
+            return readIntoFunction(state, retValueTag, binder, index + 1, tag<TTypes...>());
         }
 
         const auto& firstElem = Reader<typename std::decay<TFirstType>::type>::read(state, index);
         if (!firstElem)
             throw WrongTypeException(lua_typename(state, lua_type(state, index)), typeid(TFirstType));
 
         Binder<TCallback, const TFirstType&> binder{ callback, *firstElem };
-        return readIntoFunction(state, retValueTag, binder, index + 1, othersTags...);
+        return readIntoFunction(state, retValueTag, binder, index + 1, tag<TTypes...>());
     }
     template<typename TRetValue, typename TCallback, typename TFirstType, typename... TTypes>
-    static auto readIntoFunction(lua_State* state, tag<TRetValue> retValueTag, TCallback&& callback, int index, tag<TFirstType>, tag<TTypes>... othersTags)
+    static auto readIntoFunction(lua_State* state, tag<TRetValue> retValueTag, TCallback&& callback, int index, tag<TFirstType, TTypes...>)
         -> typename std::enable_if<!IsOptional<TFirstType>::value, TRetValue>::type
     {
         if (index >= 0)
@@ -1629,7 +1629,7 @@ class LuaContext {
             throw WrongTypeException(lua_typename(state, lua_type(state, index)), typeid(TFirstType));
 
         Binder<TCallback, const TFirstType&> binder{ callback, *firstElem };
-        return readIntoFunction(state, retValueTag, binder, index + 1, othersTags...);
+        return readIntoFunction(state, retValueTag, binder, index + 1, tag<TTypes...>());
     }
 
 
@@ -2239,14 +2239,14 @@ struct LuaContext::Pusher<TReturnType (TParameters...)>
         // pushing the result on the stack and returning number of pushed elements
         typedef Pusher<typename std::decay<TReturnType>::type>
             P;
-        return P::push(state, readIntoFunction(state, tag<TReturnType>{}, toCall, -argumentsCount, tag<TParameters>{}...));
+        return P::push(state, readIntoFunction(state, tag<TReturnType>{}, toCall, -argumentsCount, tag<TParameters...>{}));
     }
 
     template<typename TFunctionObject>
     static auto callback2(lua_State* state, TFunctionObject&& toCall, int argumentsCount)
         -> typename std::enable_if<std::is_void<TReturnType>::value && !std::is_void<TFunctionObject>::value, PushedObject>::type
     {
-        readIntoFunction(state, tag<TReturnType>{}, toCall, -argumentsCount, tag<TParameters>{}...);
+        readIntoFunction(state, tag<TReturnType>{}, toCall, -argumentsCount, tag<TParameters...>{});
         return PushedObject{state, 0};
     }
 };