Differences between gnat 4.4.5 and 4.5.1

[Noel Duffy <hobcraft-usenet@yahooxtra.co.nz>]

I recently started learning Ada using Fedora 14 and gcc-gnat 4.5.1 as my 
development environment and a copy of John Barne's book. I have another 
computer on which I installed Debian Squeeze and gcc-gnat-4.4.5. Both 
versions of gcc-gnat (I think it's gcc-gnat, the man pages describe it as 
GNU gnat) are the default versions from the distribution repositories. 
However, I noticed some differences in the generated executables created 
by these two compilers and I thought it worth investigating. The 
following (admittedly silly) program demonstrates the issue:

--
with Ada.Strings.Wide_Unbounded; use Ada.Strings.Wide_Unbounded;
with Ada.Text_IO;

procedure Hello is
   N:Unbounded_Wide_String;
begin
   Ada.Text_IO.Put_Line ("Hello World"); 
end Hello;
--

I compile on both environments with this command:

gnatmake -f -Os hello.adb -largs -s

On Fedora 14, the generated program looks like this:

$ ls -l hello
-rwxrwxr-x. 1 noeld noeld 36352 Mar 10 18:08 hello

On Debian, I see:

$ ls -l hello
-rwxr-xr-x 1 noeld noeld 13728 Mar 10 18:15 hello

I only notice this disparity in size when my programs use unbounded 
strings. I develop using dynamic languages like PHP and Python to earn a 
living so I use unbounded strings in pretty much everything. I compiled 
some larger programs and the size disparity seems to remain relatively 
fixed. E.g, I have one program whose executable is 110k on Fedora but 83k 
on Debian. Both compilers produce dynamically linked executable programs.
The programs all work equally well on both platforms.

I wonder whether what I am seeing is a result of a difference in gcc-gnat 
version, a difference in distribution packaging, or possibly a 
combination of both. Is there anyone using Fedora here who could possibly 
shed any light on this?

I must say that Ada development on Debian looks much nicer than Fedora: 
GPS is packaged along with GTK and POSIX bindings, and not forgetting the 
Ada standard in html.