WCF数据服务(WCF Data Services)

 我认为错误信息具有误导性。 问题实际上名称bar在多个基类中可用，并且您没有使用using指令将您想要的名称带入派生类范围。 
 
 这是一个工作解决方案： 
 
template <typename X, typename... Args>
class baz : public foo<X>, public baz<Args...>
{
    public:
        using foo<X>::bar;        //bring the name from the first base
        using baz<Args...>::bar;  //bring the name from the second base
};

template <typename X>
class baz<X> : public foo<X>   //specialization for one argument
{
        //no using directive needed, as there is one base only!
};
 
 完整的演示 

I think the error message is misleading. The problem is actually name bar is available in multiple base classes and you've not used using directive to bring the names you want into the derived class scope.
 
Here is one working solution:
 
template <typename X, typename... Args>
class baz : public foo<X>, public baz<Args...>
{
    public:
        using foo<X>::bar;        //bring the name from the first base
        using baz<Args...>::bar;  //bring the name from the second base
};

template <typename X>
class baz<X> : public foo<X>   //specialization for one argument
{
        //no using directive needed, as there is one base only!
};
 
Complete Demo