[Bug c++/45917] New: Friend of friend is allowed the access to the private type through the template

[Bug c++/45917] New: Friend of friend is allowed the access to the private type through the template

[yuri at tsoft dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=45917

           Summary: Friend of friend is allowed the access to the private
                    type through the template
           Product: gcc
           Version: 4.5.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
        AssignedTo: unassigned@gcc.gnu.org
        ReportedBy: yuri@tsoft.com


testcase below has struct R as private in class F.
class F declares class Q a friend, allowing it to see it's private members.
But operator<< is friend in Q, not in F.
Why is it allowed for operator<< to instantiate list<R> but not R r? This is a
bug.

--- testcase ---
#include <list>
#include <ostream>
using namespace std;

class F {
private:
  struct R {
  }; // R
  friend class Q;
  class Q {
    list<R> l;
    friend ostream& operator<<(ostream &os, const Q &q) {
      // R r; // this breaks!
      for (list<R>::const_iterator it = q.l.begin(); it != q.l.end(); it++) {
// this doesn't break! Why?
      }
      return os;
    }
  }; // Q
}; // F

[Bug c++/45917] Friend of friend is allowed the access to the private type through the template

[redi at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=45917

Jonathan Wakely <redi at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |NEW
   Last reconfirmed|                            |2010.10.06 21:40:27
     Ever Confirmed|0                           |1

--- Comment #1 from Jonathan Wakely <redi at gcc dot gnu.org> 2010-10-06 21:40:27 UTC ---
(In reply to comment #0)
> class F declares class Q a friend

There's no need for that, Q is a member of F so has access like any other
member.

Reduced:

template<class T>
struct list
{
  struct nested { };
};


class F
{
  struct R { };
  class Q
  {
    friend void f(const Q &q) { list<R>::nested n; }
  };
};

[Bug c++/45917] inaccessible types allowed as template argument in nested-name-specifier

[redi at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=45917

Jonathan Wakely <redi at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Keywords|                            |accepts-invalid
            Summary|Friend of friend is allowed |inaccessible types allowed
                   |the access to the private   |as template argument in
                   |type through the template   |nested-name-specifier

--- Comment #2 from Jonathan Wakely <redi at gcc dot gnu.org> 2010-10-06 21:48:01 UTC ---
Here's another variation that should fail but doesn't, showing this has nothing
to do with friends:

template<class T>
struct list
{
  struct nested { };
};

class F
{
  struct R { };
};

void f() { list<F::R>::nested n; }

list<F::R>::nested n;


I've changed the summary to reflect this

[Bug c++/45917] inaccessible types allowed as template argument in nested-name-specifier

[jason at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=45917

Jason Merrill <jason at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |ASSIGNED
                 CC|                            |jason at gcc dot gnu.org
         AssignedTo|unassigned at gcc dot       |jason at gcc dot gnu.org
                   |gnu.org                     |

[Bug c++/45917] inaccessible types allowed as template argument in nested-name-specifier

[jason at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=45917

--- Comment #3 from Jason Merrill <jason at gcc dot gnu.org> 2013-03-14 21:40:38 UTC ---
Created attachment 29671
  --> http://gcc.gnu.org/bugzilla/attachment.cgi?id=29671
patch

Simple fix, waiting for 4.8 to branch.

[Bug c++/45917] inaccessible types allowed as template argument in nested-name-specifier

[jason at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=45917

--- Comment #4 from Jason Merrill <jason at gcc dot gnu.org> 2013-03-17 02:39:39 UTC ---
Author: jason
Date: Sun Mar 17 02:39:22 2013
New Revision: 196744

URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=196744
Log:
    PR c++/45917
    * parser.c (cp_parser_template_id): Don't forget access checks.

Added:
    trunk/gcc/testsuite/g++.dg/template/access26.C
Modified:
    trunk/gcc/cp/ChangeLog
    trunk/gcc/cp/parser.c

[Bug c++/45917] inaccessible types allowed as template argument in nested-name-specifier

[paolo.carlini at oracle dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=45917

Paolo Carlini <paolo.carlini at oracle dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |antoinep92 at gmail dot com

--- Comment #5 from Paolo Carlini <paolo.carlini at oracle dot com> 2013-03-22 11:17:35 UTC ---
*** Bug 56687 has been marked as a duplicate of this bug. ***

[Bug c++/45917] inaccessible types allowed as template argument in nested-name-specifier

[jason at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=45917

Jason Merrill <jason at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|ASSIGNED                    |RESOLVED
         Resolution|                            |FIXED
   Target Milestone|---                         |4.9.0

--- Comment #6 from Jason Merrill <jason at gcc dot gnu.org> 2013-04-01 21:04:03 UTC ---
Fixed for 4.9.