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.

Add missing std namespace identifier

To fix warning message 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