Dear MPICH developers, When compiling the attached example with MPICH 3.1rc2 using Clang 3.3, I get the following compiler warnings: -------------------- snip -------------------- mpi2int.c:17:20: warning: argument type 'int *' doesn't match specified 'MPI' type tag [-Wtype-safety] MPI_Reduce(in, out, 1, MPI_2INT, MPI_MAXLOC, 0, MPI_COMM_WORLD); ^~~ ~~~~~~~~ mpi2int.c:17:16: warning: argument type 'int *' doesn't match specified 'MPI' type tag [-Wtype-safety] MPI_Reduce(in, out, 1, MPI_2INT, MPI_MAXLOC, 0, MPI_COMM_WORLD); ^~ ~~~~~~~~ 2 warnings generated. -------------------- snip -------------------- According to the MPI standard, however, MPI_2INT is a datatype as if defined by MPI_Type_contiguous(2, MPI_INT, MPI_2INT) i.e., 'int[2]' should be a perfect match. This is not necessarily true for the type used for comparison, struct mpich_struct_mpi_2int { int i1; int i2; }; which will only be contiguous if the compiler does not add any padding. Is there any chance this gets fixed for the final 3.1 release? Or did I miss something? Thanks, Markus -- Dr. Markus Geimer Juelich Supercomputing Centre Institute for Advanced Simulation Forschungszentrum Juelich GmbH 52425 Juelich, Germany Phone: +49-2461-61-1773 Fax: +49-2461-61-6656 E-mail: [email protected] WWW: http://www.fz-juelich.de/jsc/ ------------------------------------------------------------------------------------------------ ------------------------------------------------------------------------------------------------ Forschungszentrum Juelich GmbH 52425 Juelich Sitz der Gesellschaft: Juelich Eingetragen im Handelsregister des Amtsgerichts Dueren Nr. HR B 3498 Vorsitzender des Aufsichtsrats: MinDir Dr. Karl Eugen Huthmacher Geschaeftsfuehrung: Prof. Dr. Achim Bachem (Vorsitzender), Karsten Beneke (stellv. Vorsitzender), Prof. Dr.-Ing. Harald Bolt, Prof. Dr. Sebastian M. Schmidt ------------------------------------------------------------------------------------------------ ------------------------------------------------------------------------------------------------