On May 16 2014, Bill Long wrote:

...

From my viewpoint, yes. MPI_Sizeof has never been an ordinary Fortran function. I don't know the latest polymorphic features well enough to know whether it even CAN be implemented within the standard. Indeed, one reasonable way to implement it is by the mpif90 command running a preprocessor on the source to replace it by the relevant value!

The MPI subroutine MPI_SIZEOF is restricted to arguments of intrinsic numeric type (integer, real, complex). No derived types or polymorphic arguments. Fortran does have an intrinsic, STORAGE_SIZE, that returns the size value in bits. Divide by 8 to get the answer for MPI_SIZEOF. ...

Only since Fortran 2008 (2011) and MPI_Sizeof is a lot older than that. I don't know how many compilers currently support STORAGE_SIZE, but I will bet that it is not all, even now. Regards, Nick Maclaren.