Documentation/Nightly/Developers/Tutorials/MigrationGuide/VTK8-to-VTK9

Transition from VTK 8.0 to VTK 9.0

This section lists categories of code changes necessary to build Slicer with VTK 9.0. Each category has a short description, an example error message, a suggested upgrade path, and references to relevant commits.

VTK9: Use const vtkIdType*

To fix error messages similar to:

/tmp/SPHARM-PDM/Modules/CLI/MetaMeshTools/vtkPolyDataToitkMesh.cxx:82:70: error: invalid initialization of non-const reference of type ‘const vtkIdType*& {aka const long long int*&}’ from an rvalue of type ‘const vtkIdType* {aka const long long int*}’
   while( triangleStrips->GetNextCell( numberOfCellPoints, cellPoints ) )
                                                                      ^
[...]
/path/to/Slicer-Release/VTK/Common/DataModel/vtkCellArray.h:1497:12: note:   initializing argument 2 of ‘int vtkCellArray::GetNextCell(vtkIdType&, const vtkIdType*&)’
 inline int vtkCellArray::GetNextCell(vtkIdType& npts, vtkIdType const*& pts) VTK_SIZEHINT(pts, npts)
            ^
/tmp/SPHARM-PDM/Modules/CLI/MetaMeshTools/vtkPolyDataToitkMesh.cxx:91:64: error: invalid initialization of non-const reference of type ‘const vtkIdType*& {aka const long long int*&}’ from an rvalue of type ‘const vtkIdType* {aka const long long int*}’
   while( polygons->GetNextCell( numberOfCellPoints, cellPoints ) )
                                                                ^                                                        ^

Replace code like this:

  vtkIdType*  cellPoints;

By this:

#if VTK_MAJOR_VERSION >= 9 || (VTK_MAJOR_VERSION >= 8 && VTK_MINOR_VERSION >= 90)
  const vtkIdType*  cellPoints;
#else
  vtkIdType*  cellPoints;
#endif

References:

• https://gitlab.kitware.com/vtk/vtk/-/merge_requests/5682

VTK9: Add missing std namespace identifier

To fix error messages similar to:

/usr/include/c++/5/iosfwd:162:34: note:   ‘std::ifstream’
/tmp/SPHARM-PDM/Modules/CLI/MetaMeshTools/MeshMath.cxx:4082:5: error: ‘ofstream’ was not declared in this scope
     ofstream output;
     ^

/usr/include/c++/5/iosfwd:162:34: note:   ‘std::ifstream’
/tmp/SPHARM-PDM/Modules/CLI/MetaMeshTools/MeshMath.cxx:4117:5: error: ‘ofstream’ was not declared in this scope
     ofstream output;
     ^

Replace code like this:

    ifstream input;
    ofstream output;

By this:

    std::ifstream input;
    std::ofstream output;

References:

• https://gitlab.kitware.com/vtk/vtk/-/issues/17740