[Bug c++/64216] New: Function template can access private sub class without being friend

[Bug c++/64216] New: Function template can access private sub class without being friend

[yyc1992 at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=64216

            Bug ID: 64216
           Summary: Function template can access private sub class without
                    being friend
           Product: gcc
           Version: 4.9.2
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: yyc1992 at gmail dot com

The following code compiles on g++ 4.9.2 while it shouldn't.
Accessing private members and access in non-templates are properly checked.
However, a function template can actually access any private sub-class without
being a friend. This problem exist for all standards I've tried
((gnu|c)++(98|03|11|14))

The code is properly rejected by clang++ 3.5.0.

```
//

class C {
    struct T2 {
    };
    static void f() {}
};

template<typename T>
static inline void
f(T)
{
    // C::f(); // This generates an error correctly
    C::T2 __attribute__((unused)) v2; // This does not generate an error
}

int
main()
{
    // C::T2 v2; // This also generates an error correctly
    f(1);
    return 0;
}

```

[Bug c++/64216] Function template can access private sub class without being friend

[redi at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=64216

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |WAITING
   Last reconfirmed|                            |2014-12-08
     Ever confirmed|0                           |1

--- Comment #1 from Jonathan Wakely <redi at gcc dot gnu.org> ---
Almost certainly a duplicate of one of the bugs linked to PR59002, 
it looks nearly identical to PR41437