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Re: g++ 4: Unrecognised Friendship [REPOST/CROSS-POST]

 
 
red floyd
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      08-04-2005
JH Trauntvein wrote:
> red floyd wrote:
>
>>JH Trauntvein wrote:
>>
>>>Consider the following example:
>>>
>>>namespace n1
>>>{
>>> class cn1_base;
>>>
>>>
>>> namespace n1_helpers
>>> {
>>> class helper1
>>> {
>>> private:
>>> int private_member;
>>> friend class cn1_base;
>>> };
>>> };
>>>
>>>
>>> class cn1_base
>>> {
>>> public:
>>> void foo()
>>> {
>>> n1_helpers::helper1 helper;
>>> helper.private_member = 1;
>>> }
>>> };
>>>};
>>>
>>>
>>>While this compiled with earlier versions of G++, G++ version 4.x fails
>>>to compile this and gives the following message:
>>>
>>> 'int n1::n1_helpers::helper1:rivate_member' is prviate within this
>>> context
>>>
>>>Fortunately, I can work around this by changing the friend declaration
>>>to the following:
>>>
>>> friend class n1::n1_base;
>>>
>>>Is this a bug in the compiler or have I misunderstood something about
>>>friendship declarations?

>>
>>See Standard paragrah 7.3.1.2, subparagraph 3. "If a friend declaration
>>in a non-local class first declares a class or function, the friend
>>class or function is a member of the innermost enclosing namespace."
>>
>>Sounds to me like it was a bug in earlier g++ versions.

>
>
> It seems to me that the key here is in the phrase, "first declares a
> class or function". The sample code that I provided had a forward
> declaration of the class in the appropriate namespace that the
> friendship declaration should have used.


I am reposting this with a cross-post to comp.lang.c++, because this is
not just a compiler issue, but a language issue.

I believe that in this case, the friend declaration is in fact the first
declaration of n1_base, and that therefore 7.3.1.2/3 applies.

 
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