The fundamental problem here is that C encourages users to work with addresses of objects and in Fortran 77, there was no user-visible addresses at all. "Pointers" in Fortran 90 are also different from addresses. In many ways, the real mistake is trying to establish a correspondence between the Fortran and C/C++ versions. Permitting "Address-sized" integers in Fortran doesn't change the fact that you can't use them in the same way in Fortran as in C. Much of the struggle in this ticket is trying to work around this, as well as the decision (in MPI 1.0) to return pointers for all attributes in C, even for integer-valued predefined attributes. Bill On Apr 4, 2009, at 12:33 PM, MPI Forum wrote:

#55: MPI-2.1 Cross-language attribute example is wrong ----------------------------------- +---------------------------------------- Reporter: jsquyres | Owner: jsquyres Type: Correction to standard | Status: assigned Priority: Waiting for reviews | Milestone: 2009/04/06 Chicago Version: MPI 2.2 | Resolution: Keywords: | Implementation: Completed ----------------------------------- +----------------------------------------

Comment(by rsthakur):

Note that if you get the value of MPI_TAG_UB in Fortran with MPI_Comm_get_attr, you will get an address-sized value (487:48, 488:1). But in C you will get a pointer to an int-sized value. Does not seem right.

-- Ticket URL: <https://svn.mpi-forum.org/trac/mpi-forum-web/ticket/55#comment:54

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William Gropp Deputy Director for Research Institute for Advanced Computing Applications and Technologies Paul and Cynthia Saylor Professor of Computer Science University of Illinois Urbana-Champaign