[Bug c++/94056] New: Bogus "private within this context" error is emitted after too-late template specialization

[drahflow at gmx dot de]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94056

            Bug ID: 94056
           Summary: Bogus "private within this context" error is emitted
                    after too-late template specialization
           Product: gcc
           Version: 10.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: drahflow at gmx dot de
  Target Milestone: ---

class outer {
  class inner {
    template<class T> void f();
  };
};

template<> void outer::inner::f<int>() {
  f<void>();
}

template<> void outer::inner::f<void>() {
}

int main(void) {
  return 0;
}

gives

wrong-error.c++:11:39: error: specialization of ‘void outer::inner::f() [with T
= void]’ after instantiation
   11 | template<> void outer::inner::f<void>() {
      |                                       ^
wrong-error.c++:11:17: error: ‘class outer::inner’ is private within this
context
   11 | template<> void outer::inner::f<void>() {
      |                 ^~~~~
wrong-error.c++:2:9: note: declared private here
    2 |   class inner {


However, the privateness of inner is entirely irrelevant to the problem.
This error is reproducible for all g++ versions I tested (4.8 - 10).