c++ - 何时以及为何会生成 std​​::__non_rtti_object 异常？

Question

我正在使用 Visual Studio 并执行有效的动态转换。启用 RTTI。

编辑:更新代码使其更真实

struct base
{
    virtual base* Clone()
    {
        base* ptr = new base;
        CopyValuesTo( ptr );
        return ptr;
    }
    virtual void CopyValuesTo( base* ptr )
    {
       ...
    }
    virtual ~base()
    {
    }
}

struct derived : public base
{
    virtual base* Clone()
    {
        derived* ptr = new derived;
        CopyValuesTo( ptr );
        return ptr;
    }
    virtual void CopyValuesTo( base* ptr )
    {
       ...
    }
    virtual ~derived()
    {
    }
}  

void Class1::UseNewSpec( base* in_ptr ) //part of a totally unrelated class
{
    derived* ptr = dynamic_cast<derived *>(in_ptr);
    if( !ptr )
       return;
    delete m_ptr;
    m_ptr = ptr->Clone(); //m_ptr is a member of Class1 of type base*
}

//usage : 
Class1 obj;
derived new_spec; 
obj.UseNewSpec( &new_spec );

当异常被抛出时，我的调试器说 in_ptr 是正确的类型。谷歌似乎特别没有帮助。有任何想法吗？干杯。

Answer 1

https://learn.microsoft.com/en-us/cpp/cpp/typeid-operator?view=vs-2019有关于 __non_rtti_object_exception 的信息。

来自 MSDN:

If the pointer does not point to a valid object, a __non_rtti_objectexception is thrown, indicating an attempt to analyze the RTTI that triggered a fault (like access violation), because the object is somehow invalid (bad pointer or the code wasn't compiled with /GR).