[mpich-discuss] Is it okay to remove F77 support?

[Zhou, Hui]

Yes, that is a much better subject line. Thanks for your input!

--
Hui Zhou


From: Ed Hartnett via discuss <discuss at mpich.org>
Date: Wednesday, January 27, 2021 at 8:04 AM
To: discuss at mpich.org <discuss at mpich.org>
Cc: Ed Hartnett <edwardjameshartnett at gmail.com>
Subject: Re: [mpich-discuss] Is it okay to remove F77 support?
A better subject line would be:
does MPI still need to support F77-only compilers.

I took netcdf-fortran to F90 compiling a good few years ago, and never heard of any complaints and problems. netcdf-fortran is used on a lot of HPC systems.

So I think it's OK if you drop support for F77-only compilers. All platforms have a fortran compiler that is at least F90 compatible.

Of course, this has no effect of F77 code, which will still compile just fine with an F90 compiler.

Ed Hartnett

On Wed, Jan 27, 2021 at 6:53 AM Håkon Strandenes via discuss <discuss at mpich.org<mailto:discuss at mpich.org>> wrote:
You must differentiate between Fortran 77 and fixed-form Fortran source
code.

I doubt there are any true Fortran 77 code around today.

I am myself maintaining a large codebase written in Fixed Form Fortran.
The code was probably Fortran 77 at some point 30-40 years ago, but not
any more. Yet we still maintain parts in Fixed Form, though. This code
is Fortran 2003 at minimum.

I do not have the Fortran 2018 standard document around, but at least
Fortran 2008 include fixed-form as an allowed source form (although
marked as deprecated). For those interested, this is chapter 3.3 "Source
form" in ISO/IEC 1539-1:2010.

F77 can only be fixed form, but that does not make any fixed-form
Fortran program F77. Fixed-form Fortran can be F2008 as well.

This must be understood correctly for this discussion to be fruitful.

Best regards,
Håkon

Den 2021-01-27 04:08, skrev Gus Correa via discuss:
> IS IT OKAY TO REMOVE F77 SUPPORT?
>
> No, NO, NO!!!! NO!
>
> Removing the support to Fortran 77 from MPI is a disastrous idea!
> Sorry to say, but it is really stupid to suppose that only because
> compilers support F90
> that you can remove F77 support from MPI.
> A lot of people, academic institutions, and probably industry,
> continue to use,
> and develop new code in F77.
>
> What matters is if the CODE is written in Fortran 90 or in Fortran 77,
> and whether it uses the Fortran 77 MPI API or the Fortran 90 MPI API,
> not whether the compiler supports Fortran 90 (and yes, if not all,
> do).
>
> There is an enormous Fortran 77 code base, written using MPI, and that
> is not likely to change for the foreseeable future.
> That is true in the Atmospheric/Climate/Ocean sciences, where I work,
>
>
> but would guess this is true in other areas of science as well.
> Just one example: The MITgcm, which has an huge community of users,
>
> is the backbone for many research projects, supports many PhD thesis,
> is 100% written in Fortran-77 and will not be changed anytime soon,
> as there is no financial support to do that.
>
> Also, this type of inquiry to the MPICH community is way too narrow.
> I don't think you should be using emails on a mailing list to base
> such a consequential decision.
> Argonne should know better which community it supports, which codes
> out there use MPI.
>
> Thank you,
>
> Gus Correa
> Lamont-Doherty Earth Observatory of Columbia University.
>
> On Tue, Jan 26, 2021 at 6:12 PM Zhou, Hui via discuss
> <discuss at mpich.org<mailto:discuss at mpich.org>> wrote:
>
>> Dear MPICH community,
>>
>> Can we assume at this point of time, that every Fortran compiler out
>> there supports Fortran 90 at least?
>>
>> --
>> Hui Zhou
>>
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