[Ada] PR ada/15846 Reject self-renaming of subprogram declaration

[Arnaud Charlet]

The compiler does not report an error on the self renaming of a
subprogram declaration when the renamed subprogram is referenced
through its expanded name. After this patch the
following test is rejected by the compiler:

package Renamings1 is
   type T1 is tagged null record;

   function "=" (left, right : in T1) return Boolean
     renames Renamings1."=";
end Renamings1;

$ gcc -c renamings1.ads 
renamings1.ads:5:06: subprogram cannot rename itself

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

2012-01-30  Javier Miranda  <miranda@adacore.com>

PR ada/15846
	* sem_ch8.adb (Analyze_Subprogram_Renaming):
	Handle self-renaming when the renamed entity is referenced using
	its expanded name.

-------------- next part --------------
Index: sem_ch8.adb
===================================================================
--- sem_ch8.adb	(revision 183694)
+++ sem_ch8.adb	(working copy)
@@ -6,7 +6,7 @@
 --                                                                          --
 --                                 B o d y                                  --
 --                                                                          --
---          Copyright (C) 1992-2011, Free Software Foundation, Inc.         --
+--          Copyright (C) 1992-2012, Free Software Foundation, Inc.         --
 --                                                                          --
 -- GNAT is free software;  you can  redistribute it  and/or modify it under --
 -- terms of the  GNU General Public License as published  by the Free Soft- --
@@ -2665,7 +2665,10 @@
          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)))
+                        and then Chars (Old_S) = Chars (New_S))
+                      or else (Nkind (Nam) = N_Expanded_Name
+                        and then Entity (Prefix (Nam)) = Current_Scope
+                        and then Chars (Selector_Name (Nam)) = Chars (New_S)))
          then
             Error_Msg_N ("subprogram cannot rename itself", N);
          end if;