Fair point; the "don't do that" aspect of changing compilers with middleware is 
exactly the type of information that you want to be able to google for.  I've 
added the following paragraph to the FAQ entry 
http://www.open-mpi.org/faq/?category=mpi-apps#override-wrappers-after-v1.0:

-----
Note that changing the underlying compiler may not work at all. For example, 
C++ and Fortran compilers are notoriously binary incompatible with each other 
(sometimes even within multiple releases of the same compiler). If you 
compile/install Open MPI with C++ compiler XYZ and then use the OMPI_CXX 
environment variable to change the mpicxx wrapper compiler to use the ABC C++ 
compiler, your application code may not compile and/or link. The traditional 
method of using multiple different compilers with Open MPI is to install Open 
MPI multiple times; each installation should be built/installed with a 
different compiler. This is annoying, but it is beyond the scope of Open MPI to 
be able to fix.
-----


On Mar 13, 2013, at 5:44 AM, Dominik Goeddeke 
<dominik.goedd...@math.tu-dortmund.de> wrote:

> Yes, sure. My point is just that "strongly discouraged" (as per the FAQ) is 
> different from "simply       will not work at all". I find that a bit 
> confusing, especially since in other areas of the FAQ, explicit workarounds 
> are stated, e.g. on how to build a Makefile rule to extract flags from an 
> mpiwrapper to pass them to the compiler manually (which is in exactly the 
> same way "strongly discouraged". Maybe adding something like "is strongly 
> discouraged and may not even work in certain cases, especially with Fortran" 
> can help.
> 
> Dominik
> 
> On 03/13/2013 11:37 AM, Paul Kapinos wrote:
>> 
>> AFAIK the GNU people change the Fotran Module syntax every time they get any 
>> chance for doing it :-( 
>> 
>> So openmpi compiled with  4.4.6 (sys-default for RHEL 6.x) definitely does 
>> not work with 4.5, 4.6, 4.7 versions of gfortran. 
>> 
>> Intel 'ifort' compiler build modules which are compatible from 11.x through 
>> 13.x versions. 
>> 
>> So, the recommended solution is to build an own  version of Open MPI with 
>> any compiler you use. 
>> 
>> Greetings, 
>> Paul 
>> 
>> 
>> P.S. As Hristo said, changing the Fortran compiler vendor and using the 
>> precompiled Fortran header would never work: the syntax of these .mod files 
>> is not standatised at all. 
>> 
>> On 03/13/13 11:05, Iliev, Hristo wrote: 
>>> However, it works if for example you configure Open MPI with the system 
>>> supplied 
>>> version of gfortran and then specify a later gfortran version, e.g. 
>>> OMPI_FC=gfortran-4.7 (unless the module format has changed in the 
>>> meantime). 
>> 
>> 
>> 
>> 
>> _______________________________________________
>> users mailing list
>> 
>> us...@open-mpi.org
>> http://www.open-mpi.org/mailman/listinfo.cgi/users
> 
> 
> -- 
> Jun.-Prof. Dr. Dominik Göddeke
> Hardware-orientierte Numerik für große Systeme
> Institut für Angewandte Mathematik (LS III)
> Fakultät für Mathematik, Technische Universität Dortmund
> 
> http://www.mathematik.tu-dortmund.de/~goeddeke
> 
> Tel. +49-(0)231-755-7218  Fax +49-(0)231-755-5933
> 
> 
> _______________________________________________
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> us...@open-mpi.org
> http://www.open-mpi.org/mailman/listinfo.cgi/users


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