Critical flaw in Macro generation: does not preserve order

[jgfouca]

Some background: I was debugging a problem on summit and I discovered that I needed to have the pnetcdf link come earlier in the link line, so I changed the config_compilers.xml like this:

FROM:

   <SLIBS>
    <append>-lxlopt -lxl -lxlsmp -L$ENV{NETCDF_C_PATH}/lib -lnetcdf -L$ENV{NETCDF_FORTRAN_PATH}/lib -lnetcdff -L$ENV{ESSL_PATH}/lib64 -lessl -L$ENV{NETLIB_LAPACK_PATH}/lib -llapack</append>
     <append MPILIB="!mpi-serial"> -L$ENV{PNETCDF_PATH}/lib -lpnetcdf -L$ENV{HDF5_PATH}/lib -lhdf5_hl -lhdf5 </append>
   </SLIBS>

TO:

   <SLIBS>
     <append MPILIB="!mpi-serial"> -L$ENV{PNETCDF_PATH}/lib -lpnetcdf -L$ENV{HDF5_PATH}/lib -lhdf5_hl -lhdf5 </append>
    <append>-lxlopt -lxl -lxlsmp -L$ENV{NETCDF_C_PATH}/lib -lnetcdf -L$ENV{NETCDF_FORTRAN_PATH}/lib -lnetcdff -L$ENV{ESSL_PATH}/lib64 -lessl -L$ENV{NETLIB_LAPACK_PATH}/lib -llapack</append>
   </SLIBS>

In other words, just moved the pnetcdf SLIBS append earlier. To my surprise, this had no impact on the link flag order generated in Macros.cmake. I checked out BuildTools/macroconditiontree.py and discovered that it does not appear to be order-preserving. Things are being sorted, stored in unordered dicts, and written without regard to the original order.

Since compilation and link flags can be order-sensitive, this strikes me as a fatal flaw... I think the entire BuildTools library may need to be rewritten.

[jgfouca]

Just FYI, i was able to hack my way around this particular problem by doing this:

   <SLIBS>
     <append MPILIB="!mpi-serial"> -L$ENV{PNETCDF_PATH}/lib -lpnetcdf -L$ENV{HDF5_PATH}/lib -lhdf5_hl -lhdf5 -lxlopt -lxl -lxlsmp -L$ENV{NETCDF_C_PATH}/lib -lnetcdf -L$ENV{NETCDF_FORTRAN_PATH}/lib -lnetcdff -L$ENV{ESSL_PATH}/lib64 -lessl -L$ENV{NETLIB_LAPACK_PATH}/lib -llapack</append>
    <append MPILIB="mpi-serial">-lxlopt -lxl -lxlsmp -L$ENV{NETCDF_C_PATH}/lib -lnetcdf -L$ENV{NETCDF_FORTRAN_PATH}/lib -lnetcdff -L$ENV{ESSL_PATH}/lib64 -lessl -L$ENV{NETLIB_LAPACK_PATH}/lib -llapack</append>
   </SLIBS>