Index: gcc/ada/exp_disp.adb
===================================================================
--- gcc/ada/exp_disp.adb	(revision 183094)
+++ gcc/ada/exp_disp.adb	(working copy)
@@ -4135,6 +4135,7 @@
                   Prim := Node (Prim_Elmt);
 
                   if Present (Interface_Alias (Prim))
+                    and then Is_Dispatching_Operation (Prim)
                     and then Find_Dispatching_Type
                                (Interface_Alias (Prim)) = Iface
                   then
@@ -4247,7 +4248,6 @@
                while Present (Prim_Elmt) loop
                   Prim     := Node (Prim_Elmt);
                   E        := Ultimate_Alias (Prim);
-                  Prim_Pos := UI_To_Int (DT_Position (E));
 
                   --  Do not reference predefined primitives because they are
                   --  located in a separate dispatch table; skip abstract and
@@ -4260,7 +4260,8 @@
                     and then not Is_Abstract_Subprogram (Alias (Prim))
                     and then not Is_Eliminated (Alias (Prim))
                     and then (not Is_CPP_Class (Root_Type (Typ))
-                               or else Prim_Pos > CPP_Nb_Prims)
+                               or else UI_To_Int
+                                         (DT_Position (E)) > CPP_Nb_Prims)
                     and then Find_Dispatching_Type
                                (Interface_Alias (Prim)) = Iface
 
@@ -5764,7 +5765,6 @@
                E            : Entity_Id;
                Prim         : Entity_Id;
                Prim_Elmt    : Elmt_Id;
-               Prim_Pos     : Nat;
                Prim_Table   : array (Nat range 1 .. Nb_Prim) of Entity_Id;
 
             begin
@@ -5777,8 +5777,7 @@
                   --  Retrieve the ultimate alias of the primitive for proper
                   --  handling of renamings and eliminated primitives.
 
-                  E        := Ultimate_Alias (Prim);
-                  Prim_Pos := UI_To_Int (DT_Position (E));
+                  E := Ultimate_Alias (Prim);
 
                   --  Do not reference predefined primitives because they are
                   --  located in a separate dispatch table; skip entities with
@@ -5794,7 +5793,8 @@
                     and then not Is_Abstract_Subprogram (E)
                     and then not Is_Eliminated (E)
                     and then (not Is_CPP_Class (Root_Type (Typ))
-                               or else Prim_Pos > CPP_Nb_Prims)
+                                or else UI_To_Int
+                                          (DT_Position (E)) > CPP_Nb_Prims)
                   then
                      pragma Assert
                        (UI_To_Int (DT_Position (Prim)) <= Nb_Prim);
Index: gcc/ada/sem_ch8.adb
===================================================================
--- gcc/ada/sem_ch8.adb	(revision 183094)
+++ gcc/ada/sem_ch8.adb	(working copy)
@@ -2662,10 +2662,13 @@
             end if;
          end if;
 
-         if not Is_Actual
-           and then (Old_S = New_S
-                      or else (Nkind (Nam) /= N_Expanded_Name
-                        and then  Chars (Old_S) = Chars (New_S)))
+         if not Is_Actual and then
+           (Old_S = New_S
+              or else (Nkind (Nam) /= N_Expanded_Name
+                and then Chars (Old_S) = Chars (New_S))
+              or else (Nkind (Nam) = N_Expanded_Name
+                and then Scope (New_S) = Entity (Prefix (Nam))
+                and then Chars (Old_S) = Chars (New_S)))
          then
             Error_Msg_N ("subprogram cannot rename itself", N);
          end if;
Index: gcc/testsuite/gnat.dg/specs/renamings1.ads
===================================================================
--- gcc/testsuite/gnat.dg/specs/renamings1.ads	(revision 0)
+++ gcc/testsuite/gnat.dg/specs/renamings1.ads	(working copy)
@@ -0,0 +1,10 @@
+-- { dg-do compile}
+
+package renaming5 is
+
+   type T1 is tagged null record;
+
+   function "=" (left, right : in T1) return Boolean
+     renames renaming5."=";  -- { dg-error "subprogram cannot rename itself" }
+
+end renaming5;
Index: gcc/testsuite/gnat.dg/specs/renamings2.ads
===================================================================
--- gcc/testsuite/gnat.dg/specs/renamings2.ads	(revision 0)
+++ gcc/testsuite/gnat.dg/specs/renamings2.ads	(working copy)
@@ -0,0 +1,10 @@
+-- { dg-do compile}
+
+package renaming6 is
+
+   type T1 is null record;
+
+   function "=" (left, right : in T1) return boolean
+     renames renaming6."=";  -- { dg-error "subprogram cannot rename itself" }
+
+end renaming6;