I apologize in advance for being ultra-pedantic. I am using MPI in a purely C++ code. Is there a way to make this warning go away? I know at least one MPICH developer who shares my disdain for compiler warnings, so I hope this isn't too unreasonable. Since I am using a C++ compiler, I can't exactly tell it to use C99 mode. /Users/jhammond/eclipse/MPICH2/trunk/install-clang/include/mpi.h:526:9: warning: 'long long' is an extension when C99 mode is not enabled [-pedantic,-Wlong-long] typedef long long MPI_Count; It's not like I'm going to lose sleep over this, but I am curious if this is an unavoidable consequence of using the MPI C bindings in C++. Or perhaps it's just because MPI implements MPI_Count using "long long". Thanks Jeff -- Jeff Hammond Argonne Leadership Computing Facility University of Chicago Computation Institute [email protected] / (630) 252-5381 http://www.linkedin.com/in/jeffhammond https://wiki.alcf.anl.gov/parts/index.php/User:Jhammond