It is not allowed to rename a component of a composite object to which
pragma Volatile_Full_Access has been applied. The following is compiled
with -gnatj55

     1. package RenamVFA is
     2.    type Int8_t is mod 2**8;
     3.    type Rec is record
     4.      A,B,C,D : Int8_t;
     5.    end record;
     6.    for Rec'Size use 32;
     7.    for Rec'Alignment use 4;
     8.    pragma Volatile_Full_Access (Rec);
     9.    R : Rec;
    10.    I1 : Int8_t renames R.A; -- illegal for now
                                |
        >>> cannot rename component of
            Volatile_Full_Access object

    11.    type Arr is array (1 .. 4) of Int8_t;
    12.    pragma Volatile_Full_Access (Arr);
    13.    A : Arr;
    14.    I2 : Int8_t renames A (1); -- illegal for now
                               |
        >>> cannot rename component of
            Volatile_Full_Access object

    15. end RenamVFA;

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

2015-05-22  Robert Dewar  <de...@adacore.com>

        * sem_ch8.adb (Analyze_Object_Renaming): Check for renaming
        component of an object to which Volatile_Full_Access applies.

Index: sem_ch8.adb
===================================================================
--- sem_ch8.adb (revision 223541)
+++ sem_ch8.adb (working copy)
@@ -912,6 +912,25 @@
               ("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 Has_Volatile_Full_Access (Entity (P))
+                       or else
+                     Has_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,

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