Misaligned address error

[shaunpatterson@gmail.com]

i'm working with some really old legacy code that seemed to be working
fine with gnat pro 3.16a1.  However, we decided to upgrade to gnat
5.

Everything built fine - however, I'm getting a misaligned address
value error at runtime:

raised PROGRAM_ERROR : data_reader.2.ada:109 misaligned address
value

The code:

  subtype Data_Type is Character;

  type Data_Type_Array is array (Natural range <>) of Data_Type;

  Data_String : Data_Type_Array (1 .. 8) := (others => Data_Type
(Ascii.Nul));
  for Data_String'Alignment use 4;
  for Data_String'Size use 8 * Data_Type'Size;
  -- global data buffer for reading and writing to file

  -- quick conversion variables
  One_Byte_Number : One_Byte_Number_Type;
  for One_Byte_Number'Address use Data_String'Address;

  Two_Byte_Number : Two_Byte_Number_Type;
  for Two_Byte_Number'Address use Data_String'Address;

  Four_Byte_Number : Four_Byte_Number_Type;
  for Four_Byte_Number'Address use Data_String'Address;

  Four_Byte_Signed_Number : Four_Byte_Signed_Number_Type;
  for Four_Byte_Signed_Number'Address use Data_String'Address;

  Four_Byte_Float : Float_Type;
  for Four_Byte_Float'Address use Data_String'Address;

  Eight_Byte_Float : Long_Float_Type;
  for Eight_Byte_Float'Address use Data_String'Address;  --- FAILS ON
THIS LINE ---


Could anyone help me make sense of this exception?

thanks
--
Shaun