Question about VTK libpython linkage

I’m looking into this bug filed against the Fedora VTK package: 1979611 – linking errors

It appears that at least some VTK libraries are not getting linked against libpython, but I don’t know why. I don’t believe we are doing anything particularly different than Ubuntu.

In particular, it seems like /usr/lib64/libvtkPythonInterpreter.so.9.1.0 should be linked as it reports undefined symbols like Py_Finalize.

Full build log is here: https://kojipkgs.fedoraproject.org//packages/vtk/9.1.0/2.fc36/data/logs/x86_64/build.log

A relevant link line:

/usr/bin/g++ -fPIC -O2 -fexceptions -g -grecord-gcc-switches -pipe -Wall -Werror=format-security -Wp,-D_FORTIFY_SOURCE=2 -Wp,-D_GLIBCXX_ASSERTIONS -specs=/usr/lib/rpm/redhat/redhat-hardened-cc1 -fstack-protector-strong -specs=/usr/lib/rpm/redhat/redhat-annobin-cc1 -m64 -mtune=generic -fasynchronous-unwind-tables -fstack-clash-protection -fcf-protection -D_UNICODE -DHAVE_UINTPTR_T -g -Wl,-lc -Wl,-z,relro -Wl,–as-needed -Wl,-z,now -specs=/usr/lib/rpm/redhat/redhat-hardened-ld -specs=/usr/lib/rpm/redhat/redhat-annobin-cc1 -Wl,–build-id=sha1 -shared -Wl,-soname,libvtkPythonInterpreter.so.1 -o lib64/libvtkPythonInterpreter.so.9.1.0 Utilities/PythonInterpreter/CMakeFiles/PythonInterpreter.dir/vtkPythonInteractiveInterpreter.cxx.o Utilities/PythonInterpreter/CMakeFiles/PythonInterpreter.dir/vtkPythonInterpreter.cxx.o -Wl,-rpath,/builddir/build/BUILD/VTK-9.1.0/build/lib64: lib64/libvtkCommonMisc.so.9.1.0 lib64/libvtkWrappingPythonCore3.10.so.9.1.0 lib64/libvtkCommonMath.so.9.1.0 lib64/libvtkkissfft.so.9.1.0 lib64/libvtkCommonCore.so.9.1.0 lib64/libvtksys.so.9.1.0 -ldl -Wl,-rpath-link,/builddir/build/BUILD/VTK-9.1.0/build/lib64

Another possibility is that the library linkage the person reports is correct - and that the library user is expected to load libpython directly.

Any help would be greatly appreciated.

Distros can probabaly set VTK_PYTHON_OPTIONAL_LINK=OFF. This is done by default to allow the interpreter loading the vtk Python package to bring its own Python library (e.g., Anaconda, system, or whatever) provided the ABI and versions are compatible. This is set up so that only the executables link to libpython and the rest just assume the symbols are around by the time they’re loaded. Since distros usually pin to specific interpreter deployments, they can just say “VTK uses this libpython, deal with it”.