[MPI3 Fortran] Fortran extra_state argument to MPI attributefunctions

[Bill Long]

N.M. Maclaren wrote:
> On May 28 2009, Bill Long wrote:
>>
>> If you know about so-called "Cray pointers" (more accurately, 
>> Livermore pointers from LRLtran),  C_PTR is just a typealias for a 
>> typeless Cray pointer  (pointer(*,*)).   In fact, that's exactly how 
>> it's defined in our iso_c_binding module.  Similarly, C_LOC has the 
>> same effect as the Cray (and other vendors) LOC function.   The 
>> intent of C_PTR and C_LOC was to give these common extensions 
>> standardized, and hence portable, names and syntax. 
>
> Yes and no.  There are a heck of a lot of restrictions to C_PTR and C_LOC
> that are intended to exclude the most problematic aspects of Cray 
> pointers,

Yes, I skimmed over that detail.  The compiler need to enforce the 
semantic restrictions associated with C_PTR and C_LOC.   These are 
restrictions on the user.  Inside the compiler, the mechanical 
implementation is the same as for Cray pointers.


-- 
Bill Long                                   longb at cray.com
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