/usr/include/tulip/cxx/ is in libtulip-dev 4.6.0dfsg-2+b5.
This file is owned by root:root, with mode 0o755.
..
/usr/include/tulip/cxx/AbstractProperty.cxx
/usr/include/tulip/cxx/Array.cxx
/usr/include/tulip/cxx/CachedPropertyAnimation.cxx
/usr/include/tulip/cxx/Circle.cxx
/usr/include/tulip/cxx/DataSet.cxx
/usr/include/tulip/cxx/Graph.cxx
/usr/include/tulip/cxx/GraphPropertiesModel.cxx
/usr/include/tulip/cxx/Matrix.cxx
/usr/include/tulip/cxx/MutableContainer.cxx
/usr/include/tulip/cxx/PropertyAnimation.cxx
/usr/include/tulip/cxx/TulipItemDelegate.cxx
/usr/include/tulip/cxx/TulipItemEditorCreators.cxx
/usr/include/tulip/cxx/Vector.cxx
/usr/include/tulip/cxx/VectorPropertyAnimation.cxx
/usr/include/tulip/cxx/minmaxproperty.cxx