[Ada] Preparation for new description of interface thunks

--- gcc/ada/exp_disp.adb
+++ gcc/ada/exp_disp.adb
@@ -1454,7 +1454,7 @@  package body Exp_Disp is
       end if;
 
       Iface_Tag := Find_Interface_Tag (Operand_Typ, Iface_Typ);
-      pragma Assert (Iface_Tag /= Empty);
+      pragma Assert (Present (Iface_Tag));
 
       --  Keep separate access types to interfaces because one internal
       --  function is used to handle the null value (see following comments)
@@ -2046,6 +2046,7 @@  package body Exp_Disp is
       Set_Ekind (Thunk_Id, Ekind (Prim));
       Set_Is_Thunk (Thunk_Id);
       Set_Convention (Thunk_Id, Convention (Prim));
+      Set_Needs_Debug_Info (Thunk_Id, Needs_Debug_Info (Target));
       Set_Thunk_Entity (Thunk_Id, Target);
 
       --  Procedure case

--- gcc/ada/exp_util.adb
+++ gcc/ada/exp_util.adb
@@ -5529,7 +5529,6 @@  package body Exp_Util is
          then
             --  Skip the tag associated with the primary table
 
-            pragma Assert (Etype (First_Tag_Component (Typ)) = RTE (RE_Tag));
             AI_Tag := Next_Tag_Component (First_Tag_Component (Typ));
             pragma Assert (Present (AI_Tag));
 
@@ -5590,14 +5589,12 @@  package body Exp_Util is
       --  primary dispatch table.
 
       if Is_Ancestor (Iface, Typ, Use_Full_View => True) then
-         pragma Assert (Etype (First_Tag_Component (Typ)) = RTE (RE_Tag));
          return First_Tag_Component (Typ);
 
       --  Otherwise we need to search for its associated tag component
 
       else
          Find_Tag (Typ);
-         pragma Assert (Found);
          return AI_Tag;
       end if;
    end Find_Interface_Tag;

--- gcc/ada/exp_util.ads
+++ gcc/ada/exp_util.ads
@@ -585,8 +585,9 @@  package Exp_Util is
    function Find_Interface_Tag
      (T     : Entity_Id;
       Iface : Entity_Id) return Entity_Id;
-   --  Ada 2005 (AI-251): Given a type T implementing the interface Iface,
-   --  return the record component containing the tag of Iface.
+   --  Ada 2005 (AI-251): Given a type T and an interface Iface, return the
+   --  record component containing the tag of Iface if T implements Iface or
+   --  Empty if it does not.
 
    function Find_Prim_Op (T : Entity_Id; Name : Name_Id) return Entity_Id;
    --  Find the first primitive operation of a tagged type T with name Name.

--- gcc/ada/fe.h
+++ gcc/ada/fe.h
@@ -159,8 +159,10 @@  extern void Get_External_Name	(Entity_Id, Boolean, String_Pointer);
 /* exp_util: */
 
 #define Is_Fully_Repped_Tagged_Type exp_util__is_fully_repped_tagged_type
+#define Find_Interface_Tag exp_util__find_interface_tag
 
 extern Boolean Is_Fully_Repped_Tagged_Type      (Entity_Id);
+extern Entity_Id Find_Interface_Tag		(Entity_Id, Entity_Id);
 
 /* lib: */
 
@@ -269,12 +271,14 @@  extern Boolean Is_OK_Static_Subtype	(Entity_Id);
 #define Defining_Entity			sem_util__defining_entity
 #define First_Actual			sem_util__first_actual
 #define Next_Actual			sem_util__next_actual
+#define Is_Variable_Size_Record 	sem_util__is_variable_size_record
 #define Requires_Transient_Scope	sem_util__requires_transient_scope
 
 extern Entity_Id Defining_Entity	(Node_Id);
 extern Node_Id First_Actual		(Node_Id);
 extern Node_Id Next_Actual		(Node_Id);
-extern Boolean Requires_Transient_Scope (Entity_Id);
+extern Boolean Is_Variable_Size_Record 	(Entity_Id Id);
+extern Boolean Requires_Transient_Scope	(Entity_Id);
 
 /* sinfo: */
 

--- gcc/ada/sem_util.adb
+++ gcc/ada/sem_util.adb
@@ -17714,9 +17714,9 @@  package body Sem_Util is
    begin
       pragma Assert (Is_Record_Type (E));
 
-      Comp := First_Entity (E);
+      Comp := First_Component (E);
       while Present (Comp) loop
-         Comp_Typ := Etype (Comp);
+         Comp_Typ := Underlying_Type (Etype (Comp));
 
          --  Recursive call if the record type has discriminants
 
@@ -17732,7 +17732,7 @@  package body Sem_Util is
             return True;
          end if;
 
-         Next_Entity (Comp);
+         Next_Component (Comp);
       end loop;
 
       return False;