Snarky comments from the NAG tech support people aside, if they could be a 
little more specific about what non-conformant Fortran code they're referring 
to, we'd be happy to work with them to get it fixed.

I'm one of the few people in the Open MPI dev community who has a clue about 
Fortran, and I'm *very far* from being a Fortran expert.  Modern Fortran is a 
legitimately complicated language.  So it doesn't surprise me that we might 
have some code in our configure tests that isn't quite right.

Let's also keep in mind that the state of F2008 support varies widely across 
compilers and versions.  The current Open MPI configure tests straddle the line 
of trying to find *enough* F2008 support in a given compiler to be sufficient 
for the mpi_f08 module without being so overly proscriptive as to disqualify 
compilers that aren't fully F2008-compliant.  Frankly, the state of F2008 
support across the various Fortran compilers was a mess when we wrote those 
configure tests; we had to cobble together a variety of complicated tests to 
figure out if any given compiler supported enough F2008 support for some / all 
of the mpi_f08 module.  That's why the configure tests are... complicated.

--
Jeff Squyres
jsquy...@cisco.com

________________________________________
From: users <users-boun...@lists.open-mpi.org> on behalf of Matt Thompson via 
users <users@lists.open-mpi.org>
Sent: Thursday, December 23, 2021 11:41 AM
To: Wadud Miah
Cc: Matt Thompson; Open MPI Users
Subject: Re: [OMPI users] NAG Fortran 2018 bindings with Open MPI 4.1.2

I heard back from NAG:

Regarding OpenMPI, we have attempted the build ourselves but cannot make sense 
of the configure script. Only the OpenMPI maintainers can do something about 
that and it looks like they assume that all compilers will just swallow 
non-conforming Fortran code. The error downgrading options for NAG compiler 
remain "-dusty", "-mismatch" and "-mismatch_all" and none of them seem to help 
with the mpi_f08 module of OpenMPI. If there is a bug in the NAG Fortran 
Compiler that is responsible for this, we would love to hear about it, but at 
the moment we are not aware of such.

So it might mean the configure script itself might need to be altered to use 
F2008 conforming code?

On Thu, Dec 23, 2021 at 8:31 AM Wadud Miah 
<wmiah...@gmail.com<mailto:wmiah...@gmail.com>> wrote:
You can contact NAG support at supp...@nag.co.uk<mailto:supp...@nag.co.uk> but 
they will look into this in the new year.

Regards,

On Thu, 23 Dec 2021, 13:18 Matt Thompson via users, 
<users@lists.open-mpi.org<mailto:users@lists.open-mpi.org>> wrote:
Oh. Yes, I am on macOS. The Linux cluster I work on doesn't have NAG 7.1 on 
it...mainly because I haven't asked for it. Until NAG fix the bug we are 
seeing, I figured why bother the admins.

Still, it does *seem* like it should work. I might ask NAG support about it.

On Wed, Dec 22, 2021 at 6:28 PM Tom Kacvinsky 
<tkacv...@gmail.com<mailto:tkacv...@gmail.com>> wrote:
On Wed, Dec 22, 2021 at 5:45 PM Tom Kacvinsky 
<tkacv...@gmail.com<mailto:tkacv...@gmail.com>> wrote:
>
> On Wed, Dec 22, 2021 at 4:11 PM Matt Thompson 
> <fort...@gmail.com<mailto:fort...@gmail.com>> wrote:
> >
> > All,
> >
> > When I build Open MPI with NAG, I have to pass in:
> >
> >   FCFLAGS"=-mismatch_all -fpp"
> >
> > this flag tells nagfor to downgrade some errors with interfaces to warnings:
> >
> >        -mismatch_all
> >                  Further downgrade consistency checking of procedure 
> > argument lists so that calls to routines in the same file which are
> >                  incorrect will produce warnings instead of error messages. 
> >  This option disables -C=calls.
> >
> > The fpp flag is how you tell NAG to do preprocessing (it doesn't 
> > automatically do it with .F90 files).
> >
> > I also have to pass in a lot of other flags as seen here:
> >
> > https://github.com/mathomp4/parcelmodulefiles/blob/main/Compiler/nag-7.1_7101/openmpi/4.1.2.lua
> >
> > Now I hadn't yet tried NAG 7.1 with Open MPI because NAG 7.1 has a bug with 
> > a library I depend on, but it does promise better F2008 support. To see 
> > what happens, I tried myself and added --enable-mpi-fortran=all, but:
> >
> > checking if building Fortran 'use mpi_f08' bindings... no
> > configure: error: Cannot build requested Fortran bindings, aborting
> >
> > Unfortunately, the NAG Fortran guru I work with is off until the new year. 
> > When he comes back, I might ask him about this. He might know something we 
> > can do to make NAG happy with mpif08.
> >
>
> The very curious thing about this is that NAG 7.1 is that mpif08
> configured properly with the macOS (Intel architecture) flavor of
> it.  But as this thread seems to indicate, it barfs on Linux.  Just
> an extra data point.
>

I'd like to recall that statement, I was not looking at the config.log
carefully enough.  I see this still, even on macOS

checking if building Fortran 'use mpi_f08' bindings... no


--
Matt Thompson
   “The fact is, this is about us identifying what we do best and
   finding more ways of doing less of it better” -- Director of Better Anna 
Rampton


--
Matt Thompson
   “The fact is, this is about us identifying what we do best and
   finding more ways of doing less of it better” -- Director of Better Anna 
Rampton

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