We have been using VTK_INSTALL_LIBRARY_DIR, VTK_INSTALL_ARCHIVE_DIR etc to control where VTK (and ParaView) install their files. We did this to simplify packaging by removing version information from install directories, and make our package simpler (it obviously won’t contain more than one VTK/ParaView). All of these variables seem to have been removed in the new build system, any replacements @ben.boeckel that can be used in VTK/ParaView master?
The GNUInstallDirs module is now used, so CMAKE_INSTALL_LIBDIR, CMAKE_INSTALL_BINDIR and friends are the variables that control the install tree layout now.
Oh, reading the end goal, there are no more versioned subdirectories other than the CMake install dir and possibly the include directory. These shouldn’t matter though if you’re using CMake targets though since the include dirs come in via usage requirements anyways. As for library names, VTK_CUSTOM_LIBRARY_SUFFIX works in VTK. Seems ParaView is hard-coded yet, but that can be made to offer PARAVIEW_CUSTOM_LIBRARY_SUFFIX as well.
It looks like the include directory and the plugins remain versioned for ParaView at least. It sounds like you are open to adding a control to remove versions from there, I opened up https://gitlab.kitware.com/paraview/paraview/issues/18955 to request this. I think having a method of turning off versioning and using GNU install dirs sounds great.