Visual Studio 编译器警告 C4250(“class1":通过优势继承“class2::membe

问题描述

以下代码生成警告 C4250.我的问题是，最好的解决方案是什么?

The following code generates warning C4250. My question is, what's the best solution to it?

class A
{
  virtual void func1();
}

class B : public A
{
}

class C : public A
{
  virtual void func1();
}

class D : public B, public C
{
}

int main()
{
  D d;
  d.func1(); // Causes warning
}

根据我所读到的，应该可以这样做:

According to what I've read it should be possible to do this:

class D : public B, public C
{
  using B::func1();
}

但是，这实际上并没有做任何事情.我目前解决的方法是:

But, this doesn't actually do anything. The way I've currently solved it is:

class D : public B, public C
{
  virtual void func1() { B::func1(); }
}

大家对此有何看法?

推荐答案

我对以下代码有同样的警告:

I had the same warning for the following code:

class Interface
{
public:
    virtual void A() = 0;
};

class Implementation : public virtual Interface
{
public:
    virtual void A() {};
};

class ExtendedInterface : public virtual Interface
{
    virtual void B() = 0;
};

class ExtendedImplementation : public ExtendedInterface , public Implementation
{
public:
    virtual void B() {};
}; 

msdn 中 Visual C++ 2005 的错误报告建议这是一个已知的错误，被认为不足以修复......他们建议在这种情况下通过使用编译指示禁用警告.我认为这对您来说也是安全的，但您应该使用虚拟继承，如 Gal Goldman 的回答所示.

This bug report for Visual C++ 2005 in msdn suggests that this is a known bug that was considered not important enough to fix... They suggest to disable the warning in this case by using a pragma. I think it is safe also in your case, but you should use virtual inheritance as shown in the answer by Gal Goldman.

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