[Bug c++/91418] New: Nested class of templated class cannot declare parent class friend

[Darrell.Wright at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=91418

            Bug ID: 91418
           Summary: Nested class of templated class cannot declare parent
                    class friend
           Product: gcc
           Version: 9.1.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: Darrell.Wright at gmail dot com
  Target Milestone: ---

As seen here https://gcc.godbolt.org/z/FvHncw. One cannot express
friend class Parent;
when parent is templated from a nested class within a member function
As a workaround, it will work with 
friend class Parent<Arg>;