Re: GNAT on Debian or Gentoo?

[Ludovic Brenta <ludovic@ludovic-brenta.org>]

Adrian Hoe writes:
> I got the following GNAT bug compiling my applications:
>
> gcc -c -I/usr/lib/ada/floristlib -I../charles/src
> -I/usr/local/include/gtkada dlg_about_pkg-callbacks.adb
> +===========================GNAT BUG DETECTED==============================+
> | 3.3.3 (SuSE Linux) (i586-suse-linux-gnu) Assert_Failure nlists.adb:836   |
> | Error detected at /usr/lib/gcc-lib/i586-suse-linux/3.3.3/adainclude/s-finimp.ads:37:1|
> |
>
> I could not trace the origin of the bug. Downgrading gnat is not
> possible. I hope 3.4 or 4.x can solve my problem. I get 3.4 and 4.x,
> the only option is to upgrade to SuSE 10. That's one of the critical
> reason I want to move away from SuSE.

The Ada front-end in GCC 3.3 is pretty much the same as in 3.2 and
3.1, and is buggy because of the move from the GCC 2.8 backend to the
GCC 3.x backend.

GCC 3.4 should be okay.

GCC 4.0 has the same problem again, due to the new Tree-SSA backend.

GCC 4.1 should be okay.

> If Debian can allow me to install unstable or testing release of
> gnat, I will definitely consider Debian to be our main
> development/test platform.

Your decision boils down to this: do you want to

(a) develop/test your programs on a stable platform, or

(b) develop/test GNAT on an unstable platform (unstable because GNAT
is part of the platform)?

If you answer (a), then Debian 3.1 "Sarge" (stable) is for you.
Debian is the only distribution that provides a stable platform for
Ada development and deployment.  My goal as a Debian maintainer is to
address the needs of people who answer (a).

If you answer (b), then there are several ways in which you can
contribute to GNAT development.  The most obvious one is to check out
the latest sources of GCC from the Subversion repository at
gcc.gnu.org, and compile them for yourself.  You can do this on any
distribution, so you can keep SuSE.

Or, you can install the package gnat-4.1 on top of Debian "Sid"
(unstable).  Then you will be able to contribute to the very
interesting transition to gnat-4.1 as the default Ada compiler for
Debian.  The ground work I'm currently doing involves patching GCC's
configure and build scripts, as well as the Ada front-end.  If that
sounds interesting to you, then please join in!

> Also, is it possible to install more than 1 release of gcc/gnat and
> switch among the release?

Possible, yes.  Easy, no.

As a consequence of my goal of providing a stable Ada platform, I have
decided to support only one version of GNAT at a time, but to support
it well.  The packages gnat, gnat-3.3, gnat-3.4, gnat-4.0 and gnat-4.1
conflict with each other.  If you want to install several of them in
parallel, you need to use either full-blown chroots, or install with
"dpkg --root" and use $PATH and "gcc -B".  I personally have a chroot
where I work on gnat-4.1, while my main installation has gnat
installed.

Here is a little summary of which versions of gnat are available in
which versions of Debian:

Sarge (stable): gnat, gnat-3.3, gnat-3.4
Etch (testing): gnat, gnat-4.0
Sid (unstable): gnat, gnat-4.0
experimental: gnat-4.1

"experimental" is not a full version of Debian; it is a small number
of packages that you must install on top of Sid.

The only supported version is gnat.  All the others are for
experimentation only.

-- 
Ludovic Brenta.