Which GCC compiler for Linux-GNAT

Which GCC compiler for Linux-GNAT

[Bernard WEISSER]

Hello everybody,

Until now, I used GNAT 3.15 compiler built on top of a GCC 2.8.1 
compiler and all was perfect for me, except that I has to use this GCC 
2.8.1 compiler for all my regular C sources (in fact not a really a 
problem). I got that GNAT distribution from the FTP 'cs.nyu.edu' server.

With the arrival of the new LINUX Slackware 9.0 release, it appeared to 
me that now a full bunch of compilers is provided (and ready to use), 
namely : C, C++, F77 and GNAT 3.15. All these front-ends are based on 
the unique GCC 3.2.2 compiler version. Using this new GNAT version, I 
succeded to compile a rather complex Ada application, but it turned out 
that the binary run quickly ended with a CONSTRAINT_ERROR.

Does anybody know which GCC compiler is the "official one" required to 
build the GNAT 3.15 compiler ? Are there 2 different teams working on 
the GNAT development and using 2 different GCC compiler ?

Thank you to everybody able to explain that to me.

Re: Which GCC compiler for Linux-GNAT

[Simon Wright]

Bernard WEISSER <bernard.weisser@wanadoo.fr> writes:

> Until now, I used GNAT 3.15 compiler built on top of a GCC 2.8.1
> compiler and all was perfect for me, except that I has to use this GCC
> 2.8.1 compiler for all my regular C sources (in fact not a really a
> problem). I got that GNAT distribution from the FTP 'cs.nyu.edu'
> server.
> 
> With the arrival of the new LINUX Slackware 9.0 release, it appeared
> to me that now a full bunch of compilers is provided (and ready to
> use), namely : C, C++, F77 and GNAT 3.15. All these front-ends are
> based on the unique GCC 3.2.2 compiler version. Using this new GNAT
> version, I succeded to compile a rather complex Ada application, but
> it turned out that the binary run quickly ended with a
> CONSTRAINT_ERROR.
> 
> Does anybody know which GCC compiler is the "official one" required to
> build the GNAT 3.15 compiler ? Are there 2 different teams working on
> the GNAT development and using 2 different GCC compiler ?

There is one team, Ada Core Technologies. GNAT 3.15, 3.16 are based on
GCC 2.8.1 and can only be built over 2.8.1. The GCC-3 series
integrates GNAT with the base GCC as one parallel set of sources.

If you need to keep a GCC-3 gcc etc for your C, F77 software but also
want GNAT 3.15, you need to be very careful NOT to install your 3.15
over the Slackware gcc binaries.

I have a utility at http://www.pushface.org/gnatfe/ which is designed
to let you do this with minimal grief: on this (Mandrake 8.2) machine,
I have GNAT 3.12a2, 3.13p, 3.14p, 3.15p, 3.16a, gcc-3.2, and
gcc-3.3-20030201:

smaug.pushface.org[4]$ gcc -v
Reading specs from /usr/lib/gcc-lib/i586-mandrake-linux-gnu/2.96/specs
gcc version 2.96 20000731 (Mandrake Linux 8.2 2.96-0.76mdk)

smaug.pushface.org[5]$ gnatgcc -v
Reading specs from /opt/3.16a/lib/gcc-lib/i686-pc-linux-gnu/2.8.1/specs
gcc version 2.8.1

smaug.pushface.org[6]$ GNAT_PREFIX=/opt/gcc-3.2 gnatgcc -v
Reading specs from /opt/gcc-3.2/lib/gcc-lib/i686-pc-linux-gnu/3.2/specs
Configured with: ../gcc-3.2/configure --prefix=/opt/gcc-3.2 --enable-languages=c,ada,gcov
Thread model: posix
gcc version 3.2

Re: Which GCC compiler for Linux-GNAT

[Preben Randhol]

Bernard WEISSER wrote:
> Hello everybody,
> 
> Until now, I used GNAT 3.15 compiler built on top of a GCC 2.8.1 
> compiler and all was perfect for me, except that I has to use this GCC 
> 2.8.1 compiler for all my regular C sources (in fact not a really a 
> problem). I got that GNAT distribution from the FTP 'cs.nyu.edu' server.

No you don't have to do that. You can have several gcc installed.

> With the arrival of the new LINUX Slackware 9.0 release, it appeared to 
> me that now a full bunch of compilers is provided (and ready to use), 
> namely : C, C++, F77 and GNAT 3.15. All these front-ends are based on 
> the unique GCC 3.2.2 compiler version. Using this new GNAT version, I 
> succeded to compile a rather complex Ada application, but it turned out 
> that the binary run quickly ended with a CONSTRAINT_ERROR.

The Gnat-gcc 3.x series are not up to speed yet, so wait with upgrading
until they have finished porting them over to the Gcc 3.x backend.

-- 
Preben Randhol                    http://www.pvv.org/~randhol/

Re: Which GCC compiler for Linux-GNAT

[ALynch]

Preben Randhol <randhol+news@pvv.org> wrote:
> Bernard WEISSER wrote:
[...]
>> With the arrival of the new LINUX Slackware 9.0 release, it appeared to 
>> me that now a full bunch of compilers is provided (and ready to use), 
>> namely : C, C++, F77 and GNAT 3.15. All these front-ends are based on 
>> the unique GCC 3.2.2 compiler version. Using this new GNAT version, I 
>> succeded to compile a rather complex Ada application, but it turned out 
>> that the binary run quickly ended with a CONSTRAINT_ERROR.

Same here with Red Hat 8.0. It appears to be the math functions that
are causing the trouble. There are at least two problem reports in the
bug database at http://gcc.gnu.org/ (PR6911 and PR9033). The first one
originated in the Debian bug tracking system and the discussion there
points to a more general problem with the support for assembly code
includes.


> The Gnat-gcc 3.x series are not up to speed yet, so wait with upgrading
> until they have finished porting them over to the Gcc 3.x backend.


Unfortunately the upgrading is done for many of us, due to the
featuritis that has infested the Linux distributors. Just like MS they
seem to think that everyone always wants the latest and greatest.

We are now using RH 8.0 because that is what the client wants - a few
months ago their baseline was still RH 7.1. "Luckily" this project is
in C++, but there are some modules which will be reimplementations of
existing Ada code. I have several test harnesses which I have been
using to compare output from the original Ada code with that of the
C++ implementation. None of them work on the new system, so I have to
keep switching between old and new environment.

What also worries me is the potential damage done to GNAT's reputation.
The major distributions advertise the fact that they have an Ada
compiler, unfortunately for the current releases it is almost useless.
A number of potential Ada newbies could be in for a disappointment.

Andrew.

Re: Which GCC compiler for Linux-GNAT

[Preben Randhol]

ALynch@slb.com wrote:
> Unfortunately the upgrading is done for many of us, due to the
> featuritis that has infested the Linux distributors. Just like MS they
> seem to think that everyone always wants the latest and greatest.

Choose Debian. It is a great distribution and the simples to maintain
and upgrade.

-- 
Preben Randhol                    http://www.pvv.org/~randhol/

Re: Which GCC compiler for Linux-GNAT

[ALynch]

Preben Randhol <randhol+news@pvv.org> wrote:
> ALynch@slb.com wrote:
>> Unfortunately the upgrading is done for many of us, due to the
>> featuritis that has infested the Linux distributors. Just like MS they
>> seem to think that everyone always wants the latest and greatest.

> Choose Debian. It is a great distribution and the simples to maintain
> and upgrade.


Thanks for the tip, but I knew that already. Over the last year a number
of people have asked "why are you using Red Hat and not Debian?".

Unfortunately that is what the client wants. For some reason they started
out with Red Hat and now they are "stuck with it" - ie. probably worried
that everything will break if they switch distributions. The move from
RH 7.1 up to RH 8.0 was bad enough, but that's a whole load of other
stories that have nothing to do with Ada...

Andrew.

Re: Which GCC compiler for Linux-GNAT

[Preben Randhol]

ALynch@slb.com wrote:
> that everything will break if they switch distributions. The move from
> RH 7.1 up to RH 8.0 was bad enough, but that's a whole load of other
> stories that have nothing to do with Ada...

Well that should tell them something. RedHat always have horrible
upgrades. In Debian it goes smoothly.


-- 
Preben Randhol                    http://www.pvv.org/~randhol/

Re: Which GCC compiler for Linux-GNAT

[Jacob Sparre Andersen]

Andrew wrote:
> Preben Randhol <randhol+news@pvv.org> wrote:
>>Bernard WEISSER wrote:

>>The Gnat-gcc 3.x series are not up to speed yet, so wait with upgrading
>>until they have finished porting them over to the Gcc 3.x backend.

Agreed.  But it might be useful to give it a try now and then.

> Unfortunately the upgrading is done for many of us, due to the
> featuritis that has infested the Linux distributors.

If you are allowed to install more than just you Linux distributors 
official packages (and are working on a supported architecture), try to 
install the binary version from ACT in "/opt/gnat-3.15p" (I think that's 
what the LSB/FHS advices).  That's what I have done on my Red Hat 7.3 
system and it seems to work fine.

> What also worries me is the potential damage done to GNAT's reputation.
> The major distributions advertise the fact that they have an Ada
> compiler, unfortunately for the current releases it is almost useless.
> A number of potential Ada newbies could be in for a disappointment.

I do what I can, to warn people about the GCC 3 based Ada compilers that 
come with the Linux distributions at the moment.  I hope I can soon stop 
doing that.

Greetings,

Jacob
-- 
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