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[gsoyez <>]

Hello,

I am using CGAL to build 2D triangulations and I recently met the following
assertion violation with CGAL 3.8 when trying to remove a point:
terminate called after throwing an instance of 'CGAL::Assertion_exception'
  what():  CGAL ERROR: assertion violation!
Expr: false
File: .../include/CGAL/Triangulation_2.h
Line: 3345
Aborted

The code below does reproduce the issue. It has been tested with the
following setups:
 - CGAL 3.8, gcc4.6, kernel 2.6.40, FC15, x86_64
 - CGAL 3.8, gcc4.6, kernel 2.6.39, Debian sid, amd64
 - CGAL 3.8, gcc4.6, kernel 2.6.38, FC15_i686
 - CGAL 3.8, gcc4.1.2, kernel 2.6.18, SLC5_x86_64
 - CGAL 3.7, gcc4.6, kernel 2.6.40, FC15_x86_64
 - CGAL 3.9-beta1, gcc4.6, kernel 2.6.40, FC15_x86_64
But the code wirks fine with CGAL-3.6.1.

As far as I can tell the problem arises in situations with near degeneracy.
Is this behaviour the desired one?

Thanks in advance for the help,
Gregory

Code to reproduce the issue:
#include <iostream>
#include <vector>
#include &lt;CGAL/Exact_predicates_inexact_constructions_kernel.h&gt;
#include &lt;CGAL/Delaunay_triangulation_2.h&gt;
#include &lt;CGAL/Triangulation_hierarchy_2.h&gt;
#include &lt;CGAL/Triangulation_vertex_base_with_info_2.h&gt;

using namespace std;

struct K : CGAL::Exact_predicates_inexact_constructions_kernel {};

const int NEW_VERTEX=-2;

/// \struct InitialisedInt
/// A class to provide an "int" with an initial value.
class InitialisedInt {
 private:
  int _val;
 public:
  inline InitialisedInt () {_val=NEW_VERTEX;};
  inline InitialisedInt& operator= (int value) {_val = value; return
*this;};
  inline int val() const {return _val;};
};

typedef CGAL::Triangulation_vertex_base_with_info_2&lt;InitialisedInt,K&gt;
Vbb;
typedef CGAL::Triangulation_hierarchy_vertex_base_2<Vbb> Vb;
typedef CGAL::Triangulation_face_base_2<K> Fb;
typedef CGAL::Triangulation_data_structure_2&lt;Vb,Fb&gt; Tds;
typedef CGAL::Delaunay_triangulation_2&lt;K,Tds&gt;  Dt;
typedef CGAL::Triangulation_hierarchy_2<Dt> Triangulation;

typedef Triangulation::Vertex_handle  Vertex_handle;
typedef Triangulation::Point          Point; /// CGAL Point structure
typedef Triangulation::Vertex_circulator Vertex_circulator;
typedef Triangulation::Face_circulator Face_circulator;
typedef Triangulation::Face_handle Face_handle;

int main(){
  Triangulation TR; // CGAL object for dealing with triangulations

  // set the original VD
  vector<Vertex_handle> vhs;
  Vertex_handle to_remove;
  cout << "inserting initial points" << endl;
  vhs.push_back(TR.insert(Point(0.8348322547154467532237731575150974094868,
1.254124245528541514715925586642697453499 )));
  vhs.push_back(TR.insert(Point(0.593123061879602953005985455092741176486 ,
0.5298490048003240415752657099801581352949)));
  vhs.push_back(TR.insert(Point(0.5995001222161800980003931726969312876463,
5.597722151272678914324387733358889818192 )));
  vhs.push_back(TR.insert(Point(-7.102324567908447683350914303446188569069,
0.0501146784479798157452279383505810983479)));
  vhs.push_back(TR.insert(Point(-7.102324567908427255247261200565844774246,
0.0501146784479798226841218422578094759956)));
  vhs.push_back(TR.insert(Point(-7.102324567991757930940366350114345550537,
0.0501146784479798226841218422578094759956)));
  vhs.push_back(TR.insert(Point(-7.102324567948808287098927394254133105278,
0.0501146784479798226841218422578094759956)));
  vhs.push_back(TR.insert(Point(-7.102324567930555332395670120604336261749,
0.0501146784479798226841218422578094759956)));
 
vhs.push_back(TR.insert(Point(0.5995001222161800980003931726969312876463,-0.6854631559069073176715392037294805049896)));

  cout << "removing the 4th point" << endl;
  TR.remove(vhs[3]);

  return 0;
}


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