Hello, I'm writing a code that uses Boost.MPI to send some GMP (http://gmplib.org/) datatypes around. Since I do not want to change GMP, I'm using the "non-intrusive" serialization support (code in attached file "gmpxx_boost_serialization.hpp"). However, I'm running into a strange include-order mess: * If I include first my "gmpxx_boost_serialization.hpp" and _then_ "boost/mpi.h", then I get a slew of errors (attached file "errors.txt") * If I reverse the include order, and include "boost/mpi.h" _first_, then everything compiles fine. Is this to be expected, or am I doing something wrong in my code? For the record, I'm compiling on Ubuntu 10.10, gcc 4.4.5, arch. amd64. Thanks for any hint! Best regards, Riccardo Murri -- Riccardo Murri, Hadlaubstr. 150, 8006 Zürich (CH)