Re: How to build gnat on top of egcs-1.1.2, please?

["David C. Hoos, Sr." <david.c.hoos.sr@ada95.com>]

Gary Gourley <not@here.org> wrote in message
news:372FE594.818795BA@here.org...
> Hi,
>
> To experience the power of Ada programming I download the
> source of gnat-3.11p. However, from the README.BUILD file, I
> find that it is supposed to be built on top of gcc-2.8.1
> only.
>
> Please let me know how to build gnat on top of egcs-1.1.2 on
> my Linux box. Thanks
>
As is more often than not the case with questions of this kind,
only a small part of the required information is supplied.

You make no mention of which Linux distribution (e.g., RedHat,
Slackware, etc.) or which hardware platform (e.g., Standard PC,
Power PC, etc.).

The best place for answers to GNAT on Linux is the Ada for
Linux Team.  their web site is at
http://www.cl.cam.ac.uk/~mgk25/linux-ada/

You can contact the team on Mike Feldman's
gnatlist@seas.gwu.edu mailinglist. To subscribe to this
mailing list, just send a single line message of the form

subscribe gnatlist your-first-name your-last-name

to the mailing list server listproc@seas.gwu.edu.

I am doing a major project on Linux with GNAT, but have
stayed with 2.8.1.

Some reasons for doing so are contained in this recent
posting to the Ada for Linux Team mail list, viz.:

On Wed, 3 Feb 1999, Juergen Pfeifer wrote:
>    -  Should we by default build packages based on egcs?

For the time being, I recommend the answer should clearly be: no.

Robert Dewar told me on the phone recently that an egcs built GNAT would
be very likely to be less reliable than a gcc 2.8 built GNAT. The fact
that some of the patches that are around work at all does not mean that
the result will work as correctly as one might hope. Egcs has introduced
many internal incompatibilities to gcc, some of which are rather subtle
to find and will cause problems only in rare situations. Egcs is also a
quickly moving target, and Cygnus has already an internal not yet
released new source tree that is very different from the currently
published source.

There is nothing wrong with experimenting with building gnat on egcs,
but the result should be treated with extreme care and should NOT be
what we should offer to inexperienced new users as an easy to use
package. Egcs is an *experimental* compiler and they really mean it this
way. Unfortunately, too many users seem to be more interested in
"getting the very latest thing" than in getting a really robust and
well-tested product.

We should not be so naive and get excited about egcs, just because it is
newer in some way. Some of the comments here sound as if there is a
really significant performance or any other advantage to be gained by
building gnat on top of egcs. I would like to see hard performance
numbers first before I get enthusiastic about these things. I have not
yet seen any performance improvement by egcs that would justify for me
the risk of switching to the much less well tested egcs environment. Gcc
2.8 is a pretty damn good code generator already and egcs does not seem
to contain any Ada-specific code generator improvements.

Markus

--
Markus G. Kuhn, Computer Laboratory, University of Cambridge, UK
Email: mkuhn at acm.org,  WWW: <http://www.cl.cam.ac.uk/~mgk25/>


Finally -- Why build it yourself?  Why not just use one of the several
binary GNAT distributions for Linux?

I hope this helps

David C. Hoos, Sr.