[mpich-discuss] mpifort wrapper compiler?

Jeff Squyres (jsquyres) jsquyres at cisco.com
Fri Dec 6 07:08:57 CST 2013

On Dec 6, 2013, at 8:00 AM, Jeff Hammond <jeff.science at gmail.com> wrote:

>> I don't understand the point you're trying to make -- please explain?
> You said there haven't been F77 compilers for 30 years.  This assumes
> backwards compatibility of Fortran completely non-conflicting
> features.  I am asserting this is false.

I think we're getting into finer points, and I think we're both (at least essentially) right: remember that F77 restricted symbols to ***6 characters in length***.  Hence, MPI has *never* been compliant with Fortran 77.  And if you can find a fortran compiler that runs on a system built within the last 10 years that rejects 7 character symbols without any extra CLI options, well, then, more power to you. :-)

However, your overall point may still stand:

> I'm going to write some tests and get back to you.  But I know for a
> fact that the IBM XLF compiler chokes on F77 comment style when it is
> compiling in F90+ mode.

If this is correct (and doesn't just rely on the .suffix), then yes, your overall point is correct -- a single "mpifort" wrapper compiler may not be sufficient on such platforms (without putting at least a little more knowledge in the wrapper -- which doesn't sound desirable).  In such cases, I would think that you either need 2 MPICH installations (because, at least in one light, you could look at those incompatible Fortran compilers as actually different compilers), or you need to make an exception on that platform for mpif77 to be different than mpifort.

Jeff Squyres
jsquyres at cisco.com
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