C static global initialization of integers requires compile-time constants (example below).  While we may have implied that all constants could be link-time constants, this is only possible for non-integer constants, i.e. handles and buffer address constants.

% cat init.c
extern int w;
static int* p = &w;
static int q = w;

% gcc -c init.c
init.c:3:16: error: initializer element is not a compile-time constant
static int q = w;
               ^
1 error generated.

Jeff

On Tue, May 2, 2023 at 9:51 PM Rolf Rabenseifner via mpi-forum <mpi-forum@lists.mpi-forum.org> wrote:
>
> Dear implementor of an MPI library,
>
> Based on the discussion today in the MPI forum meeting,
> I have the following urgent question to you:
>
>   Did you implement all MPI constants that are described in Annex A.1.1
>     as of type "const int (or unnamed enum)"
>   as "C integer constant expression"
>     (according to the specification of the C language)?
>
> If yes, then all is okay and the proposed change of the MPI standard in
>     https://github.com/mpi-forum/mpi-standard/pull/821/files
> will not require any change of your MPI implementation.
>
> If not, then please can you tell which MPI constant(s) MPI_XXX
>
> - have you implemented in a way that
>
>  - it still can be used in an initialization expression,
>    i.e., in a application statement like
>      int x=MPI_XXX;
>  - but it cannot be used as a case-label in a switch statement like
>      switch(MPI_XXX) {
>          case MPI_XXX: printf("XXX\n");
>          default: ;
>      }
>  - and cannot be used as a fixed array length in a declaration like
>      float x[MPI_XXX];
>
> - and how implemented you such an MPI constant that this problem arises?
>
> We'll discuss this again tomorrow May 3, 2023 at the beginning
> of the MPI forum meeting.
>
> See you hopefully at the meeting,
> and hopefully reporting that you have no problem with the proposal,
>  
> kind regards
> Rolf
>  
>
> ----- Original Message -----
> > From: "Rolf Rabenseifner" <rabenseifner@hlrs.de>
> > To: "Main MPI Forum mailing list" <mpi-forum@lists.mpi-forum.org>
> > Cc: "Puri Bangalore" <pvbangalore@ua.edu>, "Claudia Blaas-Schenner" <claudia.blaas-schenner@tuwien.ac.at>, "Jeff
> > Hammond" <jeff.science@gmail.com>
> > Sent: Tuesday, May 2, 2023 2:04:01 PM
> > Subject: Re: Informal meeting announcement for the May 2023 meeting of the MPI Forum
>
> > Der forum memebers, dear Wesley,
> >
> > please can we add in the agenda after
> >
> >  Informal Errata Reading  705  Fortran has only compile-time constants   Rolf
> >
> > an additional slot
> >
> >  Errata Discussion  657 All C const int (or unnamed enum) as compile-time
> >  constants   Rolf, Jeff H.
> >
> > Bestr regards
> > Rolf
> >
> >
> > ----- Original Message -----
> >> From: "Rolf Rabenseifner" <rabenseifner@hlrs.de>
> >> To: "Main MPI Forum mailing list" <mpi-forum@lists.mpi-forum.org>
> >> Cc: "Puri Bangalore" <pvbangalore@ua.edu>, "Claudia Blaas-Schenner"
> >> <claudia.blaas-schenner@tuwien.ac.at>
> >> Sent: Saturday, April 29, 2023 7:38:00 AM
> >> Subject: Informal meeting announcement for the May 2023 meeting of the MPI Forum
> >
> >> Dear forum members,
> >>
> >> I would like to make the following announcements for the next MPI Forum Meeting
> >> (May 2-5, 2023):
> >>
> >> - informal reading and discussion
> >>    #705 Errata: Fortran has only compile-time constants    Rolf
> >>      Issue https://github.com/mpi-forum/mpi-issues/issues/705
> >>      PR    https://github.com/mpi-forum/mpi-standard/pull/819
> >>      PDF
> >>      https://github.com/mpi-forum/mpi-standard/files/11358444/mpi41-report_Issue705_PR819.pdf
> >>
> >> This errata should be completely discussed in next (May 2-5, 2023) meeting.
> >> It is then planned to have an final errata reading plus errata vote at next
> >> meeting (July 10-13, 2023).
> >>
> >> It is a bug since MPI-2.2 because a problem in C was directly mapped to Fortran.
> >> This mapping was wrong.
> >> In Fortran, there is no distinction between link-time and compile-time
> >> constants.
> >>
> >> Best regards
> >> Rolf Rabenseifner
> >
> >
> > --
> > Dr. Rolf Rabenseifner . . . . . . . . . .. . . rabenseifner@hlrs.de .
> > High Performance Computing Center (HLRS) . . . ++49(0)711/685-65530 .
> > University of Stuttgart . . . . . . www.hlrs.de/people/rabenseifner .
> > Nobelstr. 19, 70569 Stuttgart, Germany
>
> --
> Dr. Rolf Rabenseifner . . . . . . . . . .. . . rabenseifner@hlrs.de .
> High Performance Computing Center (HLRS) . . . ++49(0)711/685-65530 .
> University of Stuttgart . . . . . . www.hlrs.de/people/rabenseifner .
> Nobelstr. 19, 70569 Stuttgart, Germany
> _______________________________________________
> mpi-forum mailing list
> mpi-forum@lists.mpi-forum.org
> https://lists.mpi-forum.org/mailman/listinfo/mpi-forum



--
Jeff Hammond
jeff.science@gmail.com
http://jeffhammond.github.io/