[Ada] Interface operations that are renamings

[Arnaud Charlet]

If the parent subprogram in a type derivation is an explicit renaming of an
interface primitive, it is a regular primitive operation, and the presence of
its alias is not relevant: it has to be derived like any other primitive.

The following must compile quietly:
    gcc -c -gnat05 p2.ads
---
package P1 is
   type I1 is limited interface;
   procedure P (Self : not null access I1) is abstract;
   procedure H (Self : not null access I1) renames P;
end P1;
---
with P1;
package P2 is
   type T1 is limited new P1.I1 with private;
private
   type T1 is limited new P1.I1 with null record;
   overriding procedure P (Self : not null access T1) is null;
   overriding procedure H (Self : not null access T1) is null;
end P2;

Tested on x86_64-pc-linux-gnu, committed on trunk

2010-09-10  Ed Schonberg  <schonberg@adacore.com>

	* sem_ch3.adb (Derive_Subprograms): An interface primitive operation
	that is a renaming must be derived like any other primitive operation,
	the renamed operation is not relevant to the derivation.

-------------- next part --------------
Index: sem_ch3.adb
===================================================================
--- sem_ch3.adb	(revision 164154)
+++ sem_ch3.adb	(working copy)
@@ -12966,8 +12966,16 @@ package body Sem_Ch3 is
             --  were not covered by the parent type. We exclude here null
             --  interface primitives because they do not need special
             --  management.
+            --  We also exclude interface operations that are renamings.
+            --  If the subprogram is an explicit renaming of an interface
+            --  primitive, it is a regular primitive operation, and the
+            --  presence of its alias is not relevant: it has to be derived
+            --  like any other primitive.
 
             elsif Present (Alias (Subp))
+              and then
+                Nkind (Unit_Declaration_Node (Subp))
+                  /= N_Subprogram_Renaming_Declaration
               and then Is_Interface (Find_Dispatching_Type (Alias_Subp))
               and then not
                 (Nkind (Parent (Alias_Subp)) = N_Procedure_Specification