Question

    // UsingDirective.cpp : Defines the entry point for the console application.
    //

    #include "stdafx.h"
    #include <iostream>
    using namespace std;

    #pragma once

    #include <type_traits>

    #pragma region CheckForFailureSignalPolicy
     template<class Exception>
     struct ThrowOnFailure;

     template<class Exception>
     struct NullOnFailure;

     template<template<class>class FailureSignalPolicy>
     struct IsThrowOnFailure;





     template<>
     struct IsThrowOnFailure<ThrowOnFailure>
     {
      enum {value = 1};
     };

     template<>
     struct IsThrowOnFailure<NullOnFailure>
     {
      enum {value = 0};
     };



    #pragma endregion

      template<int v>
     struct Int2Type
     {};

     template<template<class> class FailurePolicy,class ExceptionType >
     struct IReportFailure
     {
      enum {isThrowing = IsThrowOnFailure<FailurePolicy>::value};
    #pragma region empty
      static auto reportFailure()-> typename std::conditional<isThrowing,void,std::nullptr_t>::type
      {
       return rprt_help(Int2Type<isThrowing>());
      }

      static void rprt_help(Int2Type<true>)
      {
       throw ExceptionType();
      }

      static std::nullptr_t rprt_help(Int2Type<false>)
      {
       return nullptr;
      }
    #pragma endregion
//******************************************
      template<class Argument>
      static auto reportFailure(const Argument& arg)-> typename std::conditional<isThrowing,void,std::nullptr_t>::type
      {
       return rprt_help(const Argument& arg,Int2Type<isThrowing>());
      }

      template<class Argument>
      static void rprt_help(const Argument& arg,Int2Type<true>)
      {
       throw ExceptionType(arg);
      }
      template<class Argument>
      static std::nullptr_t rprt_help(const Argument& arg,Int2Type<false>)
      {
       return nullptr;
      }
    #pragma region ExceptionType
      static auto reportFailure(const ExceptionType& ex)-> typename std::conditional<isThrowing,void,std::nullptr_t>::type
      {
       return rprt_help(const ExceptionType& ex,Int2Type<isThrowing>());
      }

      static void rprt_help(const ExceptionType& ex,Int2Type<true>)
      {
       throw ExceptionType(ex);
      }

      static std::nullptr_t rprt_help(const ExceptionType& ex,Int2Type<false>)
      {
       return nullptr;
      }
    #pragma endregion




     };

     template<template<class> class FailurePolicy, class ExceptionType>
     struct FailureSignalPolicy
     {
      enum {isThrowing = IsThrowOnFailure<FailurePolicy>::value};


      static auto
       signalFailure() -> typename std::conditional<IsThrowOnFailure<FailurePolicy>::value,void,std::nullptr_t>::type

      {
       return IReportFailure<FailurePolicy,ExceptionType>::reportFailure();
      }

      static auto
       signalFailure(const ExceptionType& ex) -> typename std::conditional<IsThrowOnFailure<FailurePolicy>::value,void,std::nullptr_t>::type

      {
       return IReportFailure<FailurePolicy,ExceptionType>::reportFailure(ex);
      }
///*******************************************
      template<class Argument>
      static auto
       signalFailure(const Argument& arg) -> typename std::conditional<IsThrowOnFailure<FailurePolicy>::value,void,std::nullptr_t>::type

      {
       return IReportFailure<FailurePolicy,ExceptionType>::reportFailure(arg);
      }
     };

     template<class ExceptionType>
     struct ThrowOnFailure : private FailureSignalPolicy<ThrowOnFailure,ExceptionType>
     {
      using FailureSignalPolicy< ::ThrowOnFailure,ExceptionType>::signalFailure; 
     };

     template<class ExceptionType>
     struct NullOnFailure : private FailureSignalPolicy<NullOnFailure,ExceptionType>
     {
      using FailureSignalPolicy< ::NullOnFailure,ExceptionType>::signalFailure;
     };


    int _tmain(int argc, _TCHAR* argv[])
    {
     try
     {
     /*ThrowOnFailure<int>::signalFailure();
     NullOnFailure<int>::signalFailure();*/
     ThrowOnFailure<std::out_of_range>::signalFailure(1);
     }
     catch(...)
     {
     }
     return 0;
    }

Trying to compile this I’m getting bizzare errors:
Error 1 error C2143: syntax error : missing ‘)’ before ‘const’
Error 2 error C2661: ‘IReportFailure::rprt_help’ : no overloaded function takes 0 arguments
Error 3 error C2059: syntax error : ‘)’

The problematic fnc is marked in code with ****

Answer 1

The body of IReportFailure::reportFailure should be changed to :

return rprt_help(arg, Int2Type<isThrowing>());