CGAL static_cast failing - c++

Question

For my thesis I am using some CGAL code written by another student a year ago. I cannot get it to build, however.
The function that is giving errors is the following:
std::set<Curve_handle> originatingCurves(PL_Arrangement arrangement, VertexHandleSet vertices)
{
std::set<Curve_handle> curves;
for (Vertex_handle vertex : vertices)
{
auto heStart = vertex->incident_halfedges();
auto heCurrent = vertex->incident_halfedges();
do
{
Halfedge_handle handle = static_cast<Halfedge_handle>(heCurrent);
//Unless the halfedge represents a piece of overlap between curves, it has only one originating curve
for (auto curve = arrangement.originating_curves_begin(handle); curve != arrangement.originating_curves_end(handle); curve++)
{
curves.emplace(static_cast<Curve_handle>(curve));
}
heCurrent++;
} while (heCurrent != heStart);
}
return curves;
}
with the line curves.emplace(static_cast<Curve_handle>(curve)); giving the following errors:
Severity Code Description Project File Line Suppression State
Error C2672 'std::_Tree<std::_Tset_traits<_Kty,_Pr,_Alloc,false>>::emplace': no matching overloaded function found CurvedNonograms c:\users\demeessias\documents\1. studie\0.masterthesis\curvednonograms-code\curvednonograms\curvednonograms\curve_manipulation.cpp 222
Error C2440 'static_cast': cannot convert from 'CGAL::Arrangement_on_surface_with_history_2<GeomTraits_,CGAL::Arr_bounded_planar_topology_traits_2<GeomTraits_,Dcel>>::Originating_curve_iterator' to 'Curve_handle' CurvedNonograms c:\users\demeessias\documents\1. studie\0.masterthesis\curvednonograms-code\curvednonograms\curvednonograms\curve_manipulation.cpp 222
The user defined types like Curve_handle are defined in the following header file:
#pragma once
#include <CGAL/Cartesian.h>
#include <CGAL/CORE_algebraic_number_traits.h>
#include <CGAL/Arr_Bezier_curve_traits_2.h>
#include <CGAL/Arrangement_2.h>
#include <CGAL/Arrangement_with_history_2.h>
#include <CGAL/Arr_extended_dcel.h>
#include <CGAL/Iso_rectangle_2.h>
#include <CGAL/Arr_walk_along_line_point_location.h>
#include <CGAL/Arr_observer.h>
//#include <CGAL/basic.h>
#include <CGAL/Exact_predicates_exact_constructions_kernel.h>
#include <CGAL/Arr_segment_traits_2.h>
#include <CGAL/Arr_polyline_traits_2.h>
struct FaceData
{
FaceData ()
{
colored = false;
solved = false;
};
bool colored = false;
bool solved = false;
};
//// Bezier curve traits ////
typedef CGAL::CORE_algebraic_number_traits Nt_traits;
typedef Nt_traits::Rational NT;
typedef Nt_traits::Rational Rational;
typedef Nt_traits::Algebraic Algebraic;
//Simple_cartesian = for easier debugging, no ref counting, values directly in objects
typedef CGAL::Cartesian<Rational> Kernel;
typedef CGAL::Cartesian<Algebraic> Alg_kernel;
//typedef Kernel::Point_2 Rat_Point;
typedef CGAL::Arr_Bezier_curve_traits_2<Kernel, Alg_kernel, Nt_traits> Traits;
typedef Traits::Curve_2 Bezier;
typedef Traits::Point_2 Point;
typedef Kernel::Iso_rectangle_2 BoundingBox;
typedef CGAL::Arr_face_extended_dcel<Traits, FaceData> Dcel;
typedef CGAL::Arrangement_with_history_2<Traits, Dcel> Arrangement; //Not really used anymore, because of crashes/problems/bugs
//// Polyline traits ////
// Instantiate the traits class using a user-defined kernel
// and Segment_traits_2.
typedef CGAL::Exact_predicates_exact_constructions_kernel PL_Kernel;
typedef CGAL::Arr_segment_traits_2<PL_Kernel> Segment_traits;
typedef CGAL::Arr_polyline_traits_2<Segment_traits> PL_traits;
// Identical instantiation can be achieved using the default Kernel:
// typedef CGAL::Arr_polyline_traits_2<> Geom_traits_2;
typedef PL_traits::Point_2 PL_Point;
typedef PL_traits::Segment_2 Segment;
typedef PL_traits::Curve_2 Polyline;
typedef CGAL::Arr_extended_dcel<PL_traits, bool/*not used*/, double, FaceData> PL_Dcel;
typedef CGAL::Arrangement_with_history_2<PL_traits, PL_Dcel> PL_Arrangement; //This is now the only type of arrangement that we actually use
//Handles
typedef PL_Arrangement::Vertex_const_handle Vertex_handle;
typedef PL_Arrangement::Halfedge_const_handle Halfedge_handle;
typedef PL_Arrangement::Curve_const_handle Curve_handle;
//Point location
typedef CGAL::Arr_walk_along_line_point_location<PL_Arrangement> PointLocationAlg;
typedef CGAL::Arr_point_location_result<PL_Arrangement>::Type PointLocationResult;
//Less function to use for (vertex/halfedge/face) handle sets
template <class Handle> struct HandleLess
{
bool operator()(Handle a, Handle b)
{
return (a.ptr() - b.ptr() < 0);
}
};
typedef std::set<Vertex_handle, HandleLess<Vertex_handle>> VertexHandleSet;
//Arrangement observer that keeps the face colours correct
class FaceColorObserver : public CGAL::Arr_observer<PL_Arrangement>
{
private:
bool coloredBeforeMerge;
public:
FaceColorObserver(PL_Arrangement& arrangement) :
CGAL::Arr_observer<PL_Arrangement>(arrangement)
{}
virtual void after_split_face(Face_handle oldFace, Face_handle newFace, bool)
{
newFace->data().colored = oldFace->data().colored;
}
virtual void before_merge_face(Face_handle face1, Face_handle face2, Halfedge_handle)
{
//The assumption is that only same-color faces get merged
CGAL_precondition(face1->data().colored == face2->data().colored);
coloredBeforeMerge = face1->data().colored;// && face2->data().colored;
}
virtual void after_merge_face(Face_handle newFace)
{
newFace->data().colored = coloredBeforeMerge;
}
};
//Arrangement of line segments
typedef CGAL::Arrangement_2<Segment_traits> Seg_Arrangement;
Previous problems I had with the codebase had to do with me using a newer version of CGAL than the original student, so I suspect that that might be the problem here as well, but I don't know how I should replace the line of code.

Answer 1

Arrangement::Originating_curve_iterator (which is also defined as Arrangement::Originating_curve_handle) has a user-defined conversion to Arrangement::Curve_handle and another to Arrangement::Curve_const_handle, so there is no problem with the statement
curves.emplace(static_cast<Curve_handle>(curve));
However, in
for (auto curve = arrangement.originating_curves_begin(handle);
curve != arrangement.originating_curves_end(handle); curve++)
the compiler assumes that curve is a non-const iterator, so just replace 'auto' with 'Curve_handle' (which is defined as PL_Arrangement::Curve_const_handle).

Answer 2

CGAL::Arrangement_on_surface_with_history_2::Originating_curve_iterator inherits from I_Dereference_iterator.
A Curve_handle is a: PL_Arrangement::Curve_const_handle. And since that does not inherit from either CGAL::Arrangement_on_surface_with_history_2::Originating_curve_iterator or I_Dereference_iterator you cannot static_cast between the 2. static_cast can only be used for down/up casts within an inheritance hierarchy.