This one snuck in during the recent big big merge.
With the if WIN32 code in the headers, we get errors like
C:\PROGRA~2\MICROS~2.0\VC\bin\cl.exe ....lots skipped.... \
/FoVTK\ThirdParty\xdmf3\vtkxdmf3\core\CMakeFiles\XdmfCoreObjects.dir\XdmfHeavyDataDescription.cpp.obj \
/FdVTK\ThirdParty\xdmf3\vtkxdmf3\core\CMakeFiles\XdmfCoreObjects.dir\ \
/FS -c C:\bbd\1c569048\source-paraview\VTK\ThirdParty\xdmf3\vtkxdmf3\core\XdmfHeavyDataDescription.cpp
C:\bbd\1c569048\build\install\include\boost-1_56\boost/smart_ptr/shared_ptr.hpp(658) : error C2562: 'boost::shared_ptr<Loki::BaseVisitor>::operator []' : 'void' function returning a value
        C:\bbd\1c569048\build\install\include\boost-1_56\boost/smart_ptr/shared_ptr.hpp(653) : see declaration of 'boost::shared_ptr<Loki::BaseVisitor>::operator []'

Really really need windows tests on the xdmf dashboard, and xdmf turned on in vtk buildbot.
This was only detected all the way up in ParaView pain.