'Size hack for enumerated types

[Victor Porton <porton@narod.ru>]

I have written the following code:

   type Flag_Type is (Libxml_Error_Save,
                      Libxml_Structured_Error_Save,
		      URI_Interning,
                      WWW_Skip_Init_Finish);
   for Flag_Type'Size use Interfaces.C.int'Size; -- hack
   for Flag_Type use (Libxml_Error_Save => 1,
                      Libxml_Structured_Error_Save => 2,
		      URI_Interning => 3,
                      WWW_Skip_Init_Finish => 4);

The code above is intended to be able to pass flag variables into certain C 
functions (accepting enum types).

But it seems that the above code has the drawback of storing in 4 or 8 bytes 
instead of one byte.

What is a better way to do this?

-- 
Victor Porton - http://portonvictor.org