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

[Jed Brown]

Bitbucket keeps saying "Something went wrong while creating your pull
request." but you can look at the branch

https://bitbucket.org/petsc/petsc/branch/jed/mpiuni-include/maint

@balay Can we simply remove the MPIUNI includes from MPI.py or should we
remove it later?  What --download packages are supported when using
MPIUNI?  I don't see any examples.

"Smith, Barry F." <bsmith at mcs.anl.gov> writes:

>> On Apr 25, 2018, at 2:47 PM, Balay, Satish <balay at mcs.anl.gov> wrote:
>> 
>> 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>
>
>   Fix these examples at the same time.
>> 
>> 
>>>> 
>>>>> 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.
>
>    Ah, yes
>
>> 
>> 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