GNAT 3.03 and Address Clauses

[Rob Pettit <pettit@software.org>]

I have been trying to compile the following code as an example of using the Address 
clause in Ada 95:

     with System.Storage_Elements;     
     package Address_Test is

        type Device_Data_Type is record
           Field_1 : Integer;
           Field_2 : Integer;
        end record;

        Device_Data    : Device_Data_Type;   
        Device_Address : constant System.Address 
           := System.Storage_Elements.To_Address(16#FFFF_0000#);

        for Device_Data'Address use Device_Address;

     end Address_Test;

GNAT 3.03 subsequently gives the following error message:

     address_test.ads:13:32: invalid address clause for "Device_Data"
     address_test.ads:13:32: must be constant defined before "Device_Data" 
        (RM 13.1(22))

Can anyone provide advice for compiling this code using GNAT?
Thanks in advance!

-- Rob Pettit
--------------------------------------------------------------------    
Robert G. Pettit IV     
Member, Technical Staff  
Software Productivity Consortium
2214 Rock Hill Road                     Phone:   703-742-7318
Herndon, VA 22070                       E-Mail:  pettit@software.org
--------------------------------------------------------------------