[Bug c++/82204] New: G++ doesn't connect friend and extern declarations

[jason at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=82204

            Bug ID: 82204
           Summary: G++ doesn't connect friend and extern declarations
           Product: gcc
           Version: 8.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: jason at gcc dot gnu.org
  Target Milestone: ---

This testcase fails to link because the compiler doesn't associate the local
extern with the friend, so it doesn't know we need to instantiate the friend.

template <class T>
struct A
{ 
  friend void f(A*) { };
};

template <class T>
void g(T* p) {
  extern void f(T*);
  f(p);
}

int main()
{ 
  A<int> a;
  g(&a);
}