gcc does not allow a private member function to be a friend of another class

gcc does not allow a private member function to be a friend of another class

[Denner, Brett]

In Stroustrup's "The C++ Programming Language," section 11.5, the
following example is given:

=====================================
class List_iterator {
    int* next();
}

class List {
    friend int* List_iterator::next();
}
=====================================

When I compile it with gcc, I get the following output:

=====================================
    test.cpp:2: error: `int* List_iterator::next()' is private
    test.cpp:6: error: within this context
=====================================

Stroustrup's book seems to indicate that this should work.

Here's my output from gcc -v:

=====================================
Reading specs from
/home/brett/local/lib/gcc/i686-pc-linux-gnu/3.4.1/specs
Configured with: ../gcc-3.4.1/configure --prefix=/home/brett/local
--enable-languages=c,c++,f77,java
Thread model: posix
gcc version 3.4.1
=====================================

A similar problem occurs if next() is a protected member, but not if
next() is a public member.

Thanks,

Brett

Re: gcc does not allow a private member function to be a friend of another class

[James E Wilson]

Denner, Brett wrote:
> In Stroustrup's "The C++ Programming Language," section 11.5, the
> following example is given:

This is documented in the gcc-3.4 release notes.  See
     http://gcc.gnu.org/gcc-3.4/changes.html
scroll down to the C++ section, and then scroll down to the 15th bullet. 
  There is also a pointer to a defect report that makes it clear that 
your testcase is not valid ISO C++.

You probably want to read the rest of the C++ section in the gcc release 
notes also.   Lots of useful info here.

There is an option -fno-access-control that will make this work, but you 
are probably better off fixing your code.
-- 
Jim Wilson, GNU Tools Support, http://www.SpecifixInc.com