g++: 'protected' member function cannot be declared friend

[Matt Austern]

On Jan 31, 2005, at 1:12 PM, Matt Austern wrote:

> On Jan 31, 2005, at 1:05 PM, Fariborz Jahanian wrote:
>
>>
>> g++ issues a diagnostic on this test case.
>> Section 11.4 does not address this issue, but I think that this is a 
>> g++ bug. The
>> fact that a member function itself is 'protected' should not prevent 
>> it from accessing members of other
>> classes where it is declared as 'friend'.
>>
>>
>> % cat protected.C
>> class FOO {
>> protected:
>>         void Push();
>> };
>>
>> class S {
>>         friend void FOO::Push();
>> };
>
> The problem is the other way around.  FOO::Push() is allowed to access 
> private members of classes that declare it to be a friend, but nobody 
> said that class S was allowed to access FOO's private or protected 
> members.  This code is illegal.

Oh, and I should mention: the place where this is addressed is 11.4/7: 
"A name nominated by a friend declaration shall be accessible in the 
scope of the class containing the friend declaration".  This is an 
error because the name FOO::Push is not accessible in the scope of S.

			--Matt