Non-library entities added to NC_FLIBS (CMakeLists.txt)

[Jeffrey Frey]

Versions: 4.5.4, 4.6.0

The CMake build system creates the list of library dependencies in NC_FLIBS by looping over the link libraries associated with the netcdff target:

get_target_property(ALL_TLL_LIBS netcdff LINK_LIBRARIES)

FOREACH(_LIB ${ALL_TLL_LIBS})
   :

One item in the LINK_LIBRARIES list is the netcdff_c library — which is declared as an OBJECT library in fortran/CMakeLists.txt. An OBJECT library does not produce a STATIC or SHARED library, just a set of object files. Nevertheless, -lnetcdff_c gets added to NC_FLIBS and ends up in the nf-config script. For builds using MPI, an additional non-library dependency MPI::MPI_Fortran exists in LINK_LIBRARIES and gets added as -lMPI::MPI_Fortran to nf-config.

The result is that any build system using nf-config to generate a library dependency list includes these non-library components that cannot be resolved by the linker:

$ nf-config --flibs
-L/opt/shared/netcdf-fortran/4.5.4/lib -lnetcdff -lnetcdf -lnetcdf -lnetcdff_c

and

$ nf-config --flibs
-L/opt/shared/netcdf-fortran/4.5.4-openmpi/lib -lnetcdff -lnetcdf -lnetcdf -lnetcdff_c -lMPI::MPI_Fortran

[Ward Fisher]

Thanks; let me take a look at how to clean this up!