对基类模板成员函数的访问不明确

在Visual Studio 2008中,编译器无法解析对 SetCustomer 在里面 _tmain 下面要说清楚:

template <typename TConsumer>
struct Producer
{
    void SetConsumer(TConsumer* consumer) { consumer_ = consumer; }

    TConsumer* consumer_;
};

struct AppleConsumer
{
};

struct MeatConsumer
{
};

struct ShillyShallyProducer : public Producer<AppleConsumer>,
                              public Producer<MeatConsumer>
{
};

int _tmain(int argc, _TCHAR* argv[])
{
    ShillyShallyProducer producer;
    AppleConsumer consumer;
    producer.SetConsumer(&consumer);   //  <--- Ambiguous call!!

    return 0;
}

这是编译错误:

// error C2385: ambiguous access of 'SetConsumer'
//    could be the 'SetConsumer' in base 'Producer<AppleConsumer>'
//    or could be the 'SetConsumer' in base 'Producer<MeatConsumer>'

我认为模板参数查找机制足够聪明,可以推断出正确的基 Producer . 为什么不是?

我可以通过改变 生产者 到

template <typename TConsumer>
struct Producer
{
    template <typename TConsumer2>
    void SetConsumer(TConsumer2* consumer) { consumer_ = consumer; }

    TConsumer* consumer_;
};

并打电话 SetConsumer 作为

    producer.SetConsumer<AppleConsumer>(&consumer);   // Unambiguous call!!

但如果我不需要…