[Bug c++/53403] New: Function template friend denied access to private types of granting template class.

[ibugs at qult dot net]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=53403

             Bug #: 53403
           Summary: Function template friend denied access to private
                    types of granting template class.
    Classification: Unclassified
           Product: gcc
           Version: 4.7.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
        AssignedTo: unassigned@gcc.gnu.org
        ReportedBy: ibugs@qult.net


The following code compiles with GCC 4.4 but not since 4.5, until at least
4.7.0.

  template <typename T>
  class Foo {
    typedef void    type;
    template <typename U> friend void f();
  public:
    Foo() {}
  };

  template class Foo<void>;

  template <typename T>
  void f()
  {
    typedef Foo<void>::type    type;
  }

  int main()
  {
    f<void>();
  }

If the function template is declared before the definition of the class
template, or if the Foo<void> class is instantiated after f's definition, the
code compiles.  The error appears only with private types, not other private
members.

Easy to work around, but still... :/