[petsc-dev] Install location for MPIUNI mpi.h

[Satish Balay]

On Wed, 25 Apr 2018, Smith, Barry F. wrote:

> 
> 
> > On Apr 25, 2018, at 2:31 PM, Jed Brown <jed at jedbrown.org> wrote:
> > 
> > "Smith, Barry F." <bsmith at mcs.anl.gov> writes:
> > 
> >>> On Apr 25, 2018, at 1:36 PM, Jed Brown <jed at jedbrown.org> wrote:
> >>> 
> >>> It is currently installed to include/petsc/mpiuni/mpi.h and petscsys.h
> >>> includes it as <mpi.h>, which means that users of MPIUNI need to put
> >>> -I/prefix/include/petsc/mpiuni in their command lines.  Matt and I agree
> >>> that this is bad.  We disagree on the solution.
> >>> 
> >>> He wants to install it to /prefix/include/mpi.h as though the user had
> >>> written --download-mpich.  This would conflict if a user later installs
> >>> a real MPI to that location.
> >> 
> >>  Jed,
> >> 
> >>   So you propose in petscsys.h ?
> >> 
> >> #if defined(PETSC_HAVE_MPIUNI)
> >> #include <petsc/mpiuni/mpi.h> 
> >> #else
> >> #include <mpi.h>
> >> #endif
> >> 
> >>  I don't have a problem with this.
> > 
> > Yes, and same installation layout as today.
> 
>    Ok, this is far better than copying the mpiuni mpi.h file to a public place (Matt's suggestion) and is a bit better than requiring the extra -I flag (Satish's suggestion) 
> 

All approaches have drawbacks. This approach breaks user code. I guess thats easy to work arround [and fix these
examples awell]

$ git grep '<mpi\.h>' |grep examples
src/dm/examples/tests/ex42.c:#include <mpi.h>
src/tao/leastsquares/examples/tutorials/chwirut2.c:#include <mpi.h>


> > 
> >> I notice that the Fortran petscsys.h is scattered full of weird MPIUni specific stuff like
> >> 
> >> #if defined (PETSC_HAVE_MPIUNI)
> >> #include "mpiunifdef.h"
> >> #endif
> >> 
> >> #if defined(PETSC_HAVE_MPIUNI)
> >> #define MPI_Comm PetscFortranInt
> >> #define MPI_Group PetscFortranInt
> >> #define PetscMPIInt PetscFortranInt
> >> #else
> >> #define MPI_Comm integer
> >> #define MPI_Group integer
> >> #define PetscMPIInt integer
> >> #endif

I might have diverged from mpi standard to prevent '-i8' affecting petsc+mpiuni code.

Satish

> >> 
> >> It seems PETSc Fortran does not use the standard mpif.h file? 
> > 
> > Yuck.
> 
>    I don't remember the history of this construct. There must have been a reason years ago that may no longer exist, I don't know.
> 
>    Barry
> 
> 
>