[Bug or feature] nested class inheritance

[Bradley Smith]

Thomas Kuehne wrote:
> -----BEGIN PGP SIGNED MESSAGE-----
> Hash: SHA1
> 
> David Ferenczi schrieb am 2007-04-15:
>> Compiling the code below gives an error message:
>>
>> ----------------8<---------------------------------
>> int main(char[][] args)
>> {
>>     class A
>>     {
>>         protected:
>>             class AA {}
>>     }
>>
>>     class B : A
>>     {
>>         protected:
>>             class BB : AA {}
>>     }
>>
>>     return 0;
>> }
>> ----------------8<---------------------------------
>>
>>
>> test.d(15): class test.main.B.BB super class AA is nested within A, not B
>>
>>
>> Is it the intended behaviour?
> Yes
> 
>> Does it mean that nested classes wont get inherited, thus cannot be used in
>> the subclass?
> 
> No. The classes are defined inside a function and thus:
> # (http://www.digitalmars.com/d/function.html)
> # Unlike module level declarations, declarations within function scope
> # are processed in order.
> #
> 
> Thomas

I don't understand this answer. If the classes are moved to the module 
level, the same error results. Why?

class A
{
     protected:
         class AA {}
}

class B : A
{
     protected:
         class BB : AA {}
}

int main(char[][] args)
{
     return 0;
}

test.d(10): class test.B.BB super class AA is nested within A, not B