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

[Håkon Strandenes]

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> 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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