[Bug c++/64961] New: nested template implementation crossing namespace fails with access error

["eugene at hutorny dot in.ua" <gcc-bugzilla at gcc dot gnu dot org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=64961

            Bug ID: 64961
           Summary: nested template implementation crossing namespace
                    fails with access error
           Product: gcc
           Version: 4.8.3
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: eugene at hutorny dot in.ua

Created attachment 34686
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=34686&action=edit
code sample illustrating the issue

Consider a case:
a template with protected nested structure (Foo<>::Fo) is defined in one
namespace (foo),  and instantiated in another namespace (bar) via inheritance.

Specialization of nested templates methods fails with access error.
Compare to specialization of a outer template's method placed in exactly the
same scope and compiled with success.