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

[jakub at gcc dot gnu.org]

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

Jakub Jelinek <jakub at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |jakub at gcc dot gnu.org

--- Comment #2 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
--- gcc/cp/decl2.c.jj   2018-06-29 09:38:17.788306397 +0200
+++ gcc/cp/decl2.c      2018-06-30 09:54:59.516868946 +0200
@@ -5312,6 +5312,20 @@ mark_used (tree decl, tsubst_flags_t com
   if (DECL_ODR_USED (decl))
     return true;

+  /* If decl is local extern, recurse into corresponding decl.  */
+  if (cfun
+      && cp_function_chain
+      && cp_function_chain->extern_decl_map
+      && VAR_OR_FUNCTION_DECL_P (decl)
+      && DECL_EXTERNAL (decl))
+    {
+      struct cxx_int_tree_map *h, in;
+      in.uid = DECL_UID (decl);
+      h = cp_function_chain->extern_decl_map->find_with_hash (&in, in.uid);
+      if (h && !mark_used (h->to))
+       return false;
+    }
+
   /* Normally, we can wait until instantiation-time to synthesize DECL.
      However, if DECL is a static data member initialized with a constant
      or a constexpr function, we need it right now because a reference to
that helps with PR3698 doesn't help here.