[Bug c++/58054] New: 11.3 Friends, example from standard not compiled

[Bug c++/58054] New: 11.3 Friends, example from standard not compiled

[dushistov at mail dot ru]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=58054

            Bug ID: 58054
           Summary: 11.3 Friends, example from standard not compiled
           Product: gcc
           Version: 4.8.1
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: dushistov at mail dot ru

Here is example from standard (page 250-251),

class A {
  class B { };
  friend class X;
};

struct X : A::B { // OK: A::B accessible to friend
  A::B mx; // OK: A::B accessible to member of friend
  class Y {
    A::B my; // OK: A::B accessible to nested member of friend
  };
};


$ g++ -std=c++11 -Wall -c test_friend.cc 
test_friend.cc:2:9: error: 'class A::B' is private
   class B { };
         ^
test_friend.cc:6:15: error: within this context
 struct X : A::B { // OK: A::B accessible to friend
               ^
I suppose that lines marked as OK in C++11 standard should
not emit any errors.

[Bug c++/58054] 11.3 Friends, example from standard not compiled

[pinskia at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=58054

--- Comment #1 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
Looks like they changed how base classes are handled in C++ for C++11.
98 says this:
[class.friend]/2 

"Also, because the base-clause of the friend class is not 
part of its member declarations, the base-clause of the friend class cannot 
access the names of the private and protected members from the class granting 
friendship."

Or is this just in a need for a defect report.

[Bug c++/58054] 11.3 Friends, example from standard not compiled

[dushistov at mail dot ru]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=58054

--- Comment #2 from Evgeniy Dushistov <dushistov at mail dot ru> ---
Yes, for C++ 2003 this is invalid code(page 212):

class A {
class B { };
friend class X;
};
class X : A::B { // ill-formed: A::B cannot be accessed
// in the base-clause for X
A::B mx; // OK: A::B used to declare member of X
class Y : A::B { // OK: A::B used to declare member of X
A::B my; // ill-formed: A::B cannot be accessed
// to declare members of nested class of X
};
};

but for 2011 they looks like change behaviour.

[Bug c++/58054] 11.3 Friends, example from standard not compiled

[dushistov at mail dot ru]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=58054

--- Comment #3 from Evgeniy Dushistov <dushistov at mail dot ru> ---
Here history of changes of C++ standard that related to this bug:

http://wg21.cmeerw.net/cwg/issue372

[Bug c++/58054] 11.3 Friends, example from standard not compiled

[pinskia at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=58054

Andrew Pinski <pinskia at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |ppluzhnikov at google dot com

--- Comment #4 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
*** Bug 58053 has been marked as a duplicate of this bug. ***