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Subject: Re: (j3.2006) (SC22WG5.3757) Ballot on the technical content of
	the TR
From: Van Snyder <Van.Snyder@jpl.nasa.gov>
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Date: Mon, 08 Dec 2008 12:22:24 -0800
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On Mon, 2008-12-08 at 07:26 -0800, Craig Rasmussen wrote:
> 
> On Dec 7, 2008, at 7:46 PM, Jim Xia wrote:
> 
> > 2.) Fortran descriptors 
> > Although Fortran descriptors are used when passing assumed-shape
> > arrays, pointer arrays and allocatable arrays by many vendors, they
> > are however not universally used by all vendors.  Based on a survey
> > earlier this year (by Craig Rasmussen at J3 m183), some vendors
> > haven't adopted descriptors for assumed shape arrays, pointer arrays
> > or allocatable arrays.  The requirement in the C-interop TR may pose
> > implementation difficulties for those vendors.  Furthermore allowing
> > updates on Fortran descriptors from C programs will likely cause
> > safety issues and also be problematic in consistency check by some
> > vendors.  This becomes a sure way to introduce bugs difficult to
> > diagnose. 
> 
> I'm not sure what I said about descriptors at J3 m183 but I certainly
> didn't intend to give the impression that some vendors don't implement
> Fortran descriptors.  In fact, EVERY vendor I have been able to test
> does.  Some vendors don't include the rank as part of the descriptor,
> though most do.  Perhaps this is what Jim is referring to.

In any case, the TR only affects procedures with BIND(C).  Vendors can
choose to process these differently if their usual argument-passing
conventions (that is, for non-BIND(C) procedures) are incompatible with
what the TR requires.

-- 
Van Snyder                    |  What fraction of Americans believe 
Van.Snyder@jpl.nasa.gov       |  Wrestling is real and NASA is fake?
Any alleged opinions are my own and have not been approved or
disapproved by JPL, CalTech, NASA, the President, or anybody else.