[Ada] Lift restriction on renaming with Volatile_Full_Access

[Arnaud Charlet]

An arbitrary restriction was imposed on renaming in conjunction with the new
Aspect/Pragma Volatile_Full_Access for implementation reasons: the compiler
was rejecting renamings of components of Volatile_Full_Access objects.

It is lifted by this change and the following package must now be accepted:

package RenamVFA is
   type Int8_t is mod 2**8;
   type Rec is record
     A,B,C,D : Int8_t;
   end record;
   for Rec'Size use 32;
   for Rec'Alignment use 4;
   pragma Volatile_Full_Access (Rec);
   R : Rec;
   I1 : Int8_t renames R.A;
   type Arr is array (1 .. 4) of Int8_t;
   pragma Volatile_Full_Access (Arr);
   A : Arr;
   I2 : Int8_t renames A (1);
end RenamVFA;

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

2015-05-26  Eric Botcazou  <ebotcazou@adacore.com>

	* sem_ch8.adb (Analyze_Object_Renaming): Lift restriction on
	components of Volatile_Full_Access objects.

-------------- next part --------------
Index: sem_ch8.adb
===================================================================
--- sem_ch8.adb	(revision 223685)
+++ sem_ch8.adb	(working copy)
@@ -927,25 +927,6 @@
               ("renaming of conversion only allowed for tagged types", Nam);
          end if;
 
-         --  Reject renaming of component of Volatile_Full_Access object
-
-         if Nkind_In (Nam, N_Selected_Component, N_Indexed_Component) then
-            declare
-               P : constant Node_Id := Prefix (Nam);
-            begin
-               if Is_Entity_Name (P) then
-                  if Is_Volatile_Full_Access (Entity (P))
-                       or else
-                     Is_Volatile_Full_Access (Etype (P))
-                  then
-                     Error_Msg_N
-                       ("cannot rename component of Volatile_Full_Access "
-                        & "object", Nam);
-                  end if;
-               end if;
-            end;
-         end if;
-
          Resolve (Nam, T);
 
          --  If the renamed object is a function call of a limited type,