我在C中有以下情况：
>抽象基类Abstract1和Abstract2.他们是无关的.
>一个派生自Abstract1和Abstract2的Foo类
我在一个编译单位,我没有关于Foo类的信息(没有声明,没有定义).只有Abstract1和Abstract2是已知的.
(实际上,Foo甚至在DLL中定义)
将dynamic_cast允许从Abstract1 *转换为Abstract2 *？这是标准吗？
解决方法
你所描述的是一种所谓的交叉角色.对于dynamic_cast< T(v),标准在[expr.dynamic.cast] / 8
If
Cis the class type to whichTpoints or refers,the run-time
check logically executes as follows:
If,in the most derived object pointed (referred) to by
v,vpoints (refers) to a public base class subobject of aCobject [..]Otherwise,if
vpoints (refers) to apublicbase class subobject of the most derived object,and the type of the most derived object
has a base class,of typeC,that is unambiguous andpublic,the
result points (refers) to theCsubobject of the most derived
object.
即使没有关于Foo在包含演员的翻译单元中的存在的信息,这将会工作.
你也应该看看this question.
