The README instructions for PGI compilation have a typo:
Current context: - The Portland Group compilers require the "-Msignextend" compiler flag to extend the sign bit when converting from a shorter to longer integer. This is is different than other compilers (such as GNU). When compiling Open MPI with the Portland compiler suite, the following flags should be passed to Open MPI's configure script: shell$ ./configure CFLAGS=-Msignextend CXXFLAGS=-signextent \ --with-wrapper-cflags=-Msignextend \ --with-wrapper-cxxflags=-Msignextend ... This will both compile Open MPI with the proper compile flags and also automatically add "-Msignextend" when the C and C++ MPI wrapper compilers are used to compile user MPI applications. Should be: shell$ ./configure CFLAGS=-Msignextend CXXFLAGS=-Msignextend \ That fixes the CXXFLAGS definition.