[petsc-dev] Fortran interface problem in v.3.10.2

[Martin Diehl]

Hi,

some more information on this topic.

First, Adrians code is not wrong. The statement on the IBM homepage
regarding type(*) and type-bound procedures is according to my current
understanding simply not true.
However, type(*) is a feature of Fortran 2018, a standard that is not
even published.

My information mainly comes from the Intel developer zone, see 

https://software.intel.com/en-us/forums/intel-fortran-compiler-for-linux-and-mac-os-x/topic/798744
 and I have also informed the GCC/gfortran developers, 
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=87707.
I hope to get some more information in the next day and will keep you
updated.

best regards,
Martin



On Tue, 2018-10-23 at 17:25 +1300, Adrian Croucher wrote:
> hi
> 
> Thanks to you both for looking into this.
> 
> It sounds like if we want type checking in the PETSc Fortran
> interfaces, 
> which I agree is a useful thing, then no compilers are going to
> support 
> passing in these derived types with type-bound procedures via
> type(*) 
> interfaces anytime soon.
> 
> In my case the derived-type objects I'm passing in to 
> SNESSetConvergenceTest() don't really need to have type-bound
> procedures 
> (the derived type doesn't get subclassed, and there aren't really
> any 
> data-hiding considerations), it's mostly just a style thing so that
> they 
> work similarly to other derived types in the code. So I could fairly 
> easily just turn the type-bound procedures into ordinary
> subroutines, 
> not bound to any derived type.
> 
> That might be the simplest fix for me. I suppose this issue could
> still 
> affect other people, but maybe not a lot of people are using PETSc
> with 
> F2003.
> 
> - Adrian
> 
> On 23/10/18 2:55 AM, Martin Diehl wrote:
> > >     I'm sorry, I don't understand. Are you saying that the
> > > example
> > > code is not correct Fortran?
> > 
> > In the case that your interface has a type(*) argument, it is not
> > valid
> > Fortran because 'context_type' contains the type-bound procedure
> > 'context_init'. That is why the GNU compiler complains when the
> > interface exists. Apparently, without the interface it accepts it,
> > so
> > not having an interface would be a solution in that case. However,
> > the
> > Intel compiler will fail during linking with or without interface,
> > so
> > it does not seem to be a general solution.
> > At the moment, I believe that one simply has to live with the
> > limitations that type(*) imposes on the data that can be passed to
> > void*. To clarify this, I opened a thread in the Intel developer
> > zone
> > and will keep you updated
> > 
> > 
https://software.intel.com/en-us/forums/intel-fortran-compiler-for-linux-and-mac-os-x/topic/798744
> > 
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Max-Planck-Institut für Eisenforschung GmbH
Max-Planck-Straße 1
D-40237 Düsseldorf
 
Handelsregister B 2533 
Amtsgericht Düsseldorf
 
Geschäftsführung
Prof. Dr. Gerhard Dehm
Prof. Dr. Jörg Neugebauer
Prof. Dr. Dierk Raabe
Dr. Kai de Weldige
 
Ust.-Id.-Nr.: DE 11 93 58 514 
Steuernummer: 105 5891 1000


Please consider that invitations and e-mails of our institute are 
only valid if they end with …@mpie.de. 
If you are not sure of the validity please contact rco at mpie.de

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