All, As the subject says, I'm having issues building MPICH as a shared library with NAG Fortran and Clang on my MacBook. I configured mpich as: ../configure FCFLAGS="-mismatch_all -fpp" FFLAGS="-mismatch_all -fpp" --prefix=$HOME/installed/Compiler/nag-7.0_7066/mpich/4.0rc3 |& tee configure.nag-7.0_7066.log where CC=clang, CXX=clang++, and FC=nagfor (set in environment). When I do this, the configure step is fine, but upon build: make[2]: Entering directory '/Users/mathomp4/src/MPI/mpich-4.0rc3/build-nag-7.0_7066' GEN lib/libmpifort.la NAG Fortran Compiler Release 7.0(Yurakucho) Build 7066 Option error: Unrecognised option -dynamiclib make[2]: *** [Makefile:7606: lib/libmpifort.la] Error 2 make[2]: Leaving directory '/Users/mathomp4/src/MPI/mpich-4.0rc3/build-nag-7.0_7066' make[1]: *** [Makefile:30237: all-recursive] Error 1 make[1]: Leaving directory '/Users/mathomp4/src/MPI/mpich-4.0rc3/build-nag-7.0_7066' make: *** [Makefile:7300: all] Error 2 The issue seems to be that MPICH (or libtool?) assumes that flags that clang accepts will be accepted by the Fortran compiler as well. But NAG doesn't accept '-dynamiclib' as an option. (I am asking NAG about this as well.) I can kind of see places where this is happening. For example in config.status: 749:archive_cmds_FC='$CC -dynamiclib $allow_undefined_flag -o $lib $libobjs $deplibs $compiler_flags -install_name $rpath/$soname $verstring $single_module' Now, the interesting thing is this *exact same* issue happened to me with Open MPI: https://www.mail-archive.com/[email protected]//msg34635.html<https://www.mail-archive.com/[email protected]/msg34635.html> On that thread, I eventually figured out how to build Open MPI as static, but now I ran into this: https://discourse.cmake.org/t/cmake-and-mpi-fortran-cmake-doesnt-see-it/4869 My fear is that if I try and build MPICH as a static library, the same thing will happen. Does anyone at MPICH have any thoughts on this? Thanks, Matt -- Matt Thompson, SSAI, Ld Scientific Programmer/Analyst NASA GSFC, Global Modeling and Assimilation Office Code 610.1, 8800 Greenbelt Rd, Greenbelt, MD 20771 Phone: 301-614-6712 Fax: 301-614-6246 http://science.gsfc.nasa.gov/sed/bio/matthew.thompson