diff --git a/Arrangement_on_surface_2/demo/Arrangement_on_surface_2/ArrangementDemoTab.h b/Arrangement_on_surface_2/demo/Arrangement_on_surface_2/ArrangementDemoTab.h
index 54ece4964c2..febc992fd59 100644
--- a/Arrangement_on_surface_2/demo/Arrangement_on_surface_2/ArrangementDemoTab.h
+++ b/Arrangement_on_surface_2/demo/Arrangement_on_surface_2/ArrangementDemoTab.h
@@ -38,7 +38,6 @@ namespace Qt
 {
 class Callback;
 class ArrangementGraphicsItemBase;
-class ArrangementGraphicsItemBase;
 class GraphicsViewCurveInputBase;
 class GraphicsViewNavigation;
 enum class CurveType;
diff --git a/Arrangement_on_surface_2/include/CGAL/Arr_geodesic_arc_on_sphere_traits_2.h b/Arrangement_on_surface_2/include/CGAL/Arr_geodesic_arc_on_sphere_traits_2.h
index ed552b8c9fc..65ab748e0ee 100644
--- a/Arrangement_on_surface_2/include/CGAL/Arr_geodesic_arc_on_sphere_traits_2.h
+++ b/Arrangement_on_surface_2/include/CGAL/Arr_geodesic_arc_on_sphere_traits_2.h
@@ -641,8 +641,7 @@ class Arr_geodesic_arc_on_sphere_traits_2 : public Kernel_ {
      * \param[in] plane the containing plane.
      * \param[in] source the source-point direction.
      * \param[in] target the target-point direction.
-     * \pre Both endpoint lie on the given plane.
-     * \pre Both endpoint lie on the given plane.
+     * \pre Both endpoints lie on the given plane.
      */
     X_monotone_curve_2 operator()(const Point_2& source, const Point_2& target,
                                   const Direction_3& normal) const
@@ -3113,7 +3112,7 @@ class Arr_x_monotone_geodesic_arc_on_sphere_3 {
    * \param is_directed_right is the arc directed from left to right?
    * \param is_full is the arc a full circle?
    * \param is_degenerate is the arc degenerate (single point)?
-   * \pre Both endpoint lie on the given plane.
+   * \pre Both endpoints lie on the given plane.
    */
   Arr_x_monotone_geodesic_arc_on_sphere_3
   (const Arr_extended_direction_3& src,
@@ -3312,8 +3311,7 @@ class Arr_x_monotone_geodesic_arc_on_sphere_3 {
    * \param plane the containing plane.
    * \param source the source-point direction.
    * \param target the target-point direction.
-   * \pre Both endpoint lie on the given plane.
-   * \pre Both endpoint lie on the given plane.
+   * \pre Both endpoints lie on the given plane.
    */
   Arr_x_monotone_geodesic_arc_on_sphere_3
   (const Arr_extended_direction_3& source,
diff --git a/BGL/test/BGL/test_Euler_operations.cpp b/BGL/test/BGL/test_Euler_operations.cpp
index 941758cb1c3..615a4fd756d 100644
--- a/BGL/test/BGL/test_Euler_operations.cpp
+++ b/BGL/test/BGL/test_Euler_operations.cpp
@@ -17,6 +17,7 @@ test_copy_face_graph_nm_umbrella()
   T g;
   Kernel::Point_3 p(0,0,0);
 
+  // make two connected components
   CGAL::make_tetrahedron(p, p, p, p, g);
   CGAL::make_tetrahedron(p, p, p, p, g);
 
diff --git a/Boolean_set_operations_2/doc/Boolean_set_operations_2/CGAL/Boolean_set_operations_2.h b/Boolean_set_operations_2/doc/Boolean_set_operations_2/CGAL/Boolean_set_operations_2.h
index 32fbfe7a129..39faf23e21a 100644
--- a/Boolean_set_operations_2/doc/Boolean_set_operations_2/CGAL/Boolean_set_operations_2.h
+++ b/Boolean_set_operations_2/doc/Boolean_set_operations_2/CGAL/Boolean_set_operations_2.h
@@ -1104,7 +1104,7 @@ do_intersect(const General_polygon_with_holes_2<General_polygon_2<ArrTraits>>& p
  * \param traits a traits object.
  * \return `true` if `pgn1` and `pgn2` intersect in their interior and `false`
  *         otherwise.
- * \pre `GpsTraits` must be a model of the concept `GeneralPolygonSetTraits_2`.
+ *
  * \pre `GpsTraits` must be a model of the concept `GeneralPolygonSetTraits_2`.
  */
 template <typename Polygon, typename GpsTraits>
diff --git a/Circulator/test/Circulator/test_circ1.cpp b/Circulator/test/Circulator/test_circ1.cpp
index a3ffa58158f..9fdf36155dc 100644
--- a/Circulator/test/Circulator/test_circ1.cpp
+++ b/Circulator/test/Circulator/test_circ1.cpp
@@ -2380,7 +2380,6 @@ void test_circulator_from_iterator() {
         assert( ! (i == nullptr));
         assert(   i != nullptr);
         assert( i == c);
-        assert( i == c);
         // Do I reach myself.
         ++i;
         Circulator j = i;
@@ -2493,7 +2492,6 @@ void test_circulator_from_iterator() {
         assert( ! (i == nullptr));
         assert(   i != nullptr);
         assert( i == c);
-        assert( i == c);
         // Do I reach myself.
         ++i;
         Circulator j = i;
@@ -2735,7 +2733,6 @@ void test_circulator_from_iterator() {
         assert( ! (i == nullptr));
         assert(   i != nullptr);
         assert( i == c);
-        assert( i == c);
         // Do I reach myself.
         ++i;
         Circulator j = i;
@@ -2897,7 +2894,6 @@ void test_circulator_from_iterator() {
         assert( ! (i == nullptr));
         assert(   i != nullptr);
         assert( i == c);
-        assert( i == c);
         // Do I reach myself.
         ++i;
         Circulator j = i;
@@ -3308,7 +3304,6 @@ void test_circulator_from_iterator() {
         assert( ! (i == nullptr));
         assert(   i != nullptr);
         assert( i == c);
-        assert( i == c);
         // Do I reach myself.
         ++i;
         Circulator j = i;
@@ -3533,7 +3528,6 @@ void test_circulator_from_iterator() {
         assert( ! (i == nullptr));
         assert(   i != nullptr);
         assert( i == c);
-        assert( i == c);
         // Do I reach myself.
         ++i;
         Circulator j = i;
@@ -3742,7 +3736,6 @@ void test_circulator_from_container() {
         assert( ! (i == nullptr));
         assert(   i != nullptr);
         assert( i == c);
-        assert( i == c);
         // Do I reach myself.
         ++i;
         Circulator j = i;
@@ -3855,7 +3848,6 @@ void test_circulator_from_container() {
         assert( ! (i == nullptr));
         assert(   i != nullptr);
         assert( i == c);
-        assert( i == c);
         // Do I reach myself.
         ++i;
         Circulator j = i;
@@ -4097,7 +4089,6 @@ void test_circulator_from_container() {
         assert( ! (i == nullptr));
         assert(   i != nullptr);
         assert( i == c);
-        assert( i == c);
         // Do I reach myself.
         ++i;
         Circulator j = i;
@@ -4260,7 +4251,6 @@ void test_circulator_from_container() {
         assert( ! (i == nullptr));
         assert(   i != nullptr);
         assert( i == c);
-        assert( i == c);
         // Do I reach myself.
         ++i;
         Circulator j = i;
@@ -4671,7 +4661,6 @@ void test_circulator_from_container() {
         assert( ! (i == nullptr));
         assert(   i != nullptr);
         assert( i == c);
-        assert( i == c);
         // Do I reach myself.
         ++i;
         Circulator j = i;
@@ -4897,7 +4886,6 @@ void test_circulator_from_container() {
         assert( ! (i == nullptr));
         assert(   i != nullptr);
         assert( i == c);
-        assert( i == c);
         // Do I reach myself.
         ++i;
         Circulator j = i;
diff --git a/Circulator/test/Circulator/test_circ2.cpp b/Circulator/test/Circulator/test_circ2.cpp
index 697363d1cb6..1dd55f406c3 100644
--- a/Circulator/test/Circulator/test_circ2.cpp
+++ b/Circulator/test/Circulator/test_circ2.cpp
@@ -304,7 +304,6 @@ void test_struct(){
         assert( ! (i == nullptr));
         assert(   i != nullptr);
         assert( i == start);
-        assert( i == start);
         // Do I reach myself.
         ++i;
         Struct_circulator j = i;
@@ -413,7 +412,6 @@ void test_struct(){
         assert( ! (i == nullptr));
         assert(   i != nullptr);
         assert( i == start);
-        assert( i == start);
         // Do I reach myself.
         ++i;
         Struct_const_circulator j = i;
@@ -651,7 +649,6 @@ void test_struct(){
         assert( ! (i == nullptr));
         assert(   i != nullptr);
         assert( i == start);
-        assert( i == start);
         // Do I reach myself.
         ++i;
         Struct_bi_circulator j = i;
@@ -809,7 +806,6 @@ void test_struct(){
         assert( ! (i == nullptr));
         assert(   i != nullptr);
         assert( i == start);
-        assert( i == start);
         // Do I reach myself.
         ++i;
         Struct_bi_const_circulator j = i;
@@ -969,7 +965,6 @@ void test_class(){
         assert( ! (i == nullptr));
         assert(   i != nullptr);
         assert( i == start);
-        assert( i == start);
         // Do I reach myself.
         ++i;
         Class_circulator j = i;
@@ -1078,7 +1073,6 @@ void test_class(){
         assert( ! (i == nullptr));
         assert(   i != nullptr);
         assert( i == start);
-        assert( i == start);
         // Do I reach myself.
         ++i;
         Class_const_circulator j = i;
@@ -1316,7 +1310,6 @@ void test_class(){
         assert( ! (i == nullptr));
         assert(   i != nullptr);
         assert( i == start);
-        assert( i == start);
         // Do I reach myself.
         ++i;
         Class_bi_circulator j = i;
@@ -1474,7 +1467,6 @@ void test_class(){
         assert( ! (i == nullptr));
         assert(   i != nullptr);
         assert( i == start);
-        assert( i == start);
         // Do I reach myself.
         ++i;
         Class_bi_const_circulator j = i;
@@ -1891,7 +1883,6 @@ void test_array() {
         assert( ! (i == nullptr));
         assert(   i != nullptr);
         assert( i == start);
-        assert( i == start);
         // Do I reach myself.
         ++i;
         Circulator j = i;
@@ -2119,7 +2110,6 @@ void test_array() {
         assert( ! (i == nullptr));
         assert(   i != nullptr);
         assert( i == start);
-        assert( i == start);
         // Do I reach myself.
         ++i;
         Circulator j = i;
diff --git a/Combinatorial_map/include/CGAL/Combinatorial_map.h b/Combinatorial_map/include/CGAL/Combinatorial_map.h
index aaa360677b7..7bf8295c665 100644
--- a/Combinatorial_map/include/CGAL/Combinatorial_map.h
+++ b/Combinatorial_map/include/CGAL/Combinatorial_map.h
@@ -1780,7 +1780,6 @@ namespace CGAL {
     void basic_link_beta_for_involution(Dart_descriptor adart1, Dart_descriptor adart2,
                                         unsigned int i)
     {
-      CGAL_assertion( i>=2 && i<=dimension );
       CGAL_assertion( i>=2 && i<=dimension );
       dart_link_beta(adart1, adart2, i);
       dart_link_beta(adart2, adart1, i);
diff --git a/Distance_3/test/Distance_3/test_distance_3.cpp b/Distance_3/test/Distance_3/test_distance_3.cpp
index ab67ad18d79..f297e93016b 100644
--- a/Distance_3/test/Distance_3/test_distance_3.cpp
+++ b/Distance_3/test/Distance_3/test_distance_3.cpp
@@ -160,7 +160,6 @@ struct Test
     assert(are_equal(res_o2o1, expected_result));
 
     do_intersect_check(o1, o2);
-    do_intersect_check(o1, o2);
   }
 
   template <typename O1, typename O2>
@@ -169,7 +168,6 @@ struct Test
     const FT res_o1o2 = CGAL::squared_distance(o1, o2);
     const FT res_o2o1 = CGAL::squared_distance(o2, o1);
 
-    do_intersect_check(o1, o2);
     do_intersect_check(o1, o2);
 
     assert(res_o1o2 <= ubound);
@@ -324,7 +322,7 @@ struct Test
       check_squared_distance(S{p2, p3}, S{p4, p5}, 0);
       check_squared_distance(S{p2, p3}, S{p5, p4}, 0);
       check_squared_distance(S{p3, p2}, S{p4, p5}, 0);
-      check_squared_distance(S{p3, p2}, S{p4, p5}, 0);
+      check_squared_distance(S{p3, p2}, S{p5, p4}, 0);
 
       const double lambda_6 = r.get_double(0, 1);
       const P p6 = p3 + FT(lambda_6) * V{p3 - p2};
@@ -332,7 +330,7 @@ struct Test
       check_squared_distance(S{p2, p3}, S{p6, p5}, 0);
       check_squared_distance(S{p2, p3}, S{p5, p6}, 0);
       check_squared_distance(S{p3, p2}, S{p6, p5}, 0);
-      check_squared_distance(S{p3, p2}, S{p6, p5}, 0);
+      check_squared_distance(S{p3, p2}, S{p5, p6}, 0);
 
       const double lambda_7 = r.get_double(1, 2);
       const P p7 = p3 + FT(lambda_7) * V{p3 - p2};
diff --git a/Generator/doc/Generator/CGAL/point_generators_2.h b/Generator/doc/Generator/CGAL/point_generators_2.h
index 10319fca737..b273f932314 100644
--- a/Generator/doc/Generator/CGAL/point_generators_2.h
+++ b/Generator/doc/Generator/CGAL/point_generators_2.h
@@ -30,7 +30,6 @@ are needed from `rnd` for each point.
 \sa `CGAL::points_on_segment_2()`
 \sa `CGAL::points_on_square_grid_2()`
 \sa `CGAL::random_selection()`
-\sa `CGAL::random_selection()`
 \sa `std::random_shuffle()`
 
 */
diff --git a/Heat_method_3/include/CGAL/Heat_method_3/internal/Intrinsic_Delaunay_triangulation_3.h b/Heat_method_3/include/CGAL/Heat_method_3/internal/Intrinsic_Delaunay_triangulation_3.h
index 65d78512514..77a399704ec 100644
--- a/Heat_method_3/include/CGAL/Heat_method_3/internal/Intrinsic_Delaunay_triangulation_3.h
+++ b/Heat_method_3/include/CGAL/Heat_method_3/internal/Intrinsic_Delaunay_triangulation_3.h
@@ -25,7 +25,6 @@
 #include <CGAL/squared_distance_3.h>
 #include <CGAL/number_utils.h>
 #include <CGAL/Iterator_range.h>
-#include <CGAL/Iterator_range.h>
 #include <CGAL/boost/graph/helpers.h>
 #include <CGAL/boost/graph/copy_face_graph.h>
 #include <CGAL/Heat_method_3/internal/V2V.h>
diff --git a/Kernel_23/test/Kernel_23/Dimension.cpp b/Kernel_23/test/Kernel_23/Dimension.cpp
index ab9086f0e22..e5b7315d690 100644
--- a/Kernel_23/test/Kernel_23/Dimension.cpp
+++ b/Kernel_23/test/Kernel_23/Dimension.cpp
@@ -9,7 +9,6 @@
 #include <CGAL/Exact_predicates_inexact_constructions_kernel.h>
 #include <CGAL/Exact_predicates_exact_constructions_kernel.h>
 
-#include <CGAL/Dimension.h>
 #include <CGAL/Dimension.h>
 
 template < typename K >
diff --git a/Lab/demo/Lab/Plugins/PMP/Interpolated_corrected_principal_curvatures_plugin.cpp b/Lab/demo/Lab/Plugins/PMP/Interpolated_corrected_principal_curvatures_plugin.cpp
index 4a75dfd7a3b..dbe630ad09f 100644
--- a/Lab/demo/Lab/Plugins/PMP/Interpolated_corrected_principal_curvatures_plugin.cpp
+++ b/Lab/demo/Lab/Plugins/PMP/Interpolated_corrected_principal_curvatures_plugin.cpp
@@ -59,7 +59,6 @@ void compute(SMesh* sMesh,
   namespace PMP = CGAL::Polygon_mesh_processing;
   typedef CGAL::Exact_predicates_inexact_constructions_kernel Epic_kernel;
   typedef Epic_kernel::Point_3 Point;
-  typedef Epic_kernel::Point_3 Point;
   typedef Epic_kernel::Vector_3 Vector;
   typedef boost::graph_traits<SMesh>::vertex_descriptor Vertex_descriptor;
 
diff --git a/Lab/demo/Lab/Scene_textured_surface_mesh_item.cpp b/Lab/demo/Lab/Scene_textured_surface_mesh_item.cpp
index d3fdcb2996d..5ebdf60c6df 100644
--- a/Lab/demo/Lab/Scene_textured_surface_mesh_item.cpp
+++ b/Lab/demo/Lab/Scene_textured_surface_mesh_item.cpp
@@ -74,7 +74,7 @@ Scene_textured_surface_mesh_item_priv::compute_normals_and_vertices(void) const
   faces_buffer.resize(0);
 
   typedef boost::graph_traits<SMesh>::face_iterator face_iterator;
-  typedef boost::graph_traits<SMesh>::face_iterator face_iterator;
+
   const CGAL::qglviewer::Vec offset = static_cast<CGAL::Three::Viewer_interface*>(CGAL::QGLViewer::QGLViewerPool().first())->offset();
 
   //Faces
diff --git a/Mesh_2/test/Mesh_2/test_meshing.cpp b/Mesh_2/test/Mesh_2/test_meshing.cpp
index 2654f78aca9..48d6ccffaf0 100644
--- a/Mesh_2/test/Mesh_2/test_meshing.cpp
+++ b/Mesh_2/test/Mesh_2/test_meshing.cpp
@@ -10,7 +10,6 @@
 #include <CGAL/Delaunay_mesher_2.h>
 #include <CGAL/Delaunay_mesh_face_base_2.h>
 #include <CGAL/Delaunay_mesh_size_criteria_2.h>
-#include <CGAL/Delaunay_mesh_size_criteria_2.h>
 #include <CGAL/Delaunay_mesher_no_edge_refinement_2.h>
 
 #include <CGAL/IO/File_poly.h>
diff --git a/Number_types/test/Number_types/Interval_nt_new.cpp b/Number_types/test/Number_types/Interval_nt_new.cpp
index c2481700c7d..0b4e7b06495 100644
--- a/Number_types/test/Number_types/Interval_nt_new.cpp
+++ b/Number_types/test/Number_types/Interval_nt_new.cpp
@@ -122,7 +122,7 @@ int main() {
         CGAL_catch_error((bool)(I<=J),CGAL::Uncertain_conversion_exception&);
         CGAL_catch_error((bool)(I>=J),CGAL::Uncertain_conversion_exception&);
         CGAL_catch_error((bool)(J> I),CGAL::Uncertain_conversion_exception&);
-        CGAL_catch_error((bool)(J> I),CGAL::Uncertain_conversion_exception&);
+        CGAL_catch_error((bool)(J< I),CGAL::Uncertain_conversion_exception&);
         CGAL_catch_error((bool)(J>=I),CGAL::Uncertain_conversion_exception&);
         CGAL_catch_error((bool)(J<=I),CGAL::Uncertain_conversion_exception&);
 
diff --git a/Orthtree/include/CGAL/Orthtree/Traversals.h b/Orthtree/include/CGAL/Orthtree/Traversals.h
index acd1db941f6..7e06e798351 100644
--- a/Orthtree/include/CGAL/Orthtree/Traversals.h
+++ b/Orthtree/include/CGAL/Orthtree/Traversals.h
@@ -143,7 +143,6 @@ struct Leaves_traversal {
 
   \tparam Tree an instance of `Orthtree`
 
-  All tree nodes at another depth are ignored. If the selected depth is
   All tree nodes at another depth are ignored. If the selected depth is
   higher than the maximum depth of the orthtree, no node will be traversed.
 
diff --git a/Periodic_3_triangulation_3/demo/Periodic_Lloyd_3/MainWindow.cpp b/Periodic_3_triangulation_3/demo/Periodic_Lloyd_3/MainWindow.cpp
index f4eb7aeb793..fb49efad8c4 100644
--- a/Periodic_3_triangulation_3/demo/Periodic_Lloyd_3/MainWindow.cpp
+++ b/Periodic_3_triangulation_3/demo/Periodic_Lloyd_3/MainWindow.cpp
@@ -119,7 +119,7 @@ MainWindow::loadPoints()
   for (int i=0 ; i<8 ; i++) {
     cx += dom[i].x();
     cy += dom[i].y();
-    cy += dom[i].y();
+    cz += dom[i].z();
   }
   CGAL::qglviewer::Vec center(cx/8.,cy/8.,cz/8.);
   viewer->setSceneCenter(center);
@@ -188,7 +188,7 @@ MainWindow::newPoints(int n)
   for (int i=0 ; i<8 ; i++) {
     cx += dom[i].x();
     cy += dom[i].y();
-    cy += dom[i].y();
+    cz += dom[i].z();
   }
   CGAL::qglviewer::Vec center(cx/8.,cy/8.,cz/8.);
   viewer->setSceneCenter(center);
@@ -223,5 +223,3 @@ void MainWindow::help() {
       tr("Could not start Qt Assistant from %1.").arg(app));
   }
 }
-
-
diff --git a/Periodic_3_triangulation_3/include/CGAL/Periodic_3_regular_triangulation_3.h b/Periodic_3_triangulation_3/include/CGAL/Periodic_3_regular_triangulation_3.h
index 63fb9404469..4dba83f3847 100644
--- a/Periodic_3_triangulation_3/include/CGAL/Periodic_3_regular_triangulation_3.h
+++ b/Periodic_3_triangulation_3/include/CGAL/Periodic_3_regular_triangulation_3.h
@@ -931,7 +931,7 @@ class Periodic_3_regular_triangulation_3
 
         CGAL_assertion(this->int_to_off(offsets[i])[0] == 0 || this->int_to_off(offsets[i])[0] == 1);
         CGAL_assertion(this->int_to_off(offsets[i])[1] == 0 || this->int_to_off(offsets[i])[1] == 1);
-        CGAL_assertion(this->int_to_off(offsets[i])[1] == 0 || this->int_to_off(offsets[i])[1] == 1);
+        CGAL_assertion(this->int_to_off(offsets[i])[2] == 0 || this->int_to_off(offsets[i])[2] == 1);
       }
 
       c->set_offsets(offsets[0], offsets[1], offsets[2], offsets[3]);
diff --git a/Point_set_processing_3/include/CGAL/IO/write_off_points.h b/Point_set_processing_3/include/CGAL/IO/write_off_points.h
index 941bc16d518..e99a2c90bce 100644
--- a/Point_set_processing_3/include/CGAL/IO/write_off_points.h
+++ b/Point_set_processing_3/include/CGAL/IO/write_off_points.h
@@ -25,7 +25,6 @@
 
 #include <iostream>
 #include <fstream>
-#include <fstream>
 #include <iterator>
 #include <type_traits>
 
diff --git a/Polygon_mesh_processing/doc/Polygon_mesh_processing/examples.txt b/Polygon_mesh_processing/doc/Polygon_mesh_processing/examples.txt
index 3aca69fb004..08109123fa5 100644
--- a/Polygon_mesh_processing/doc/Polygon_mesh_processing/examples.txt
+++ b/Polygon_mesh_processing/doc/Polygon_mesh_processing/examples.txt
@@ -48,5 +48,5 @@
 \example Polygon_mesh_processing/remesh_almost_planar_patches.cpp
 \example Polygon_mesh_processing/sample_example.cpp
 \example Polygon_mesh_processing/soup_autorefinement.cpp
-*/
+
 */
diff --git a/Polyhedron/doc/Polyhedron/Polyhedron.txt b/Polyhedron/doc/Polyhedron/Polyhedron.txt
index e9d9cb1a5b3..9e7ac47116e 100644
--- a/Polyhedron/doc/Polyhedron/Polyhedron.txt
+++ b/Polyhedron/doc/Polyhedron/Polyhedron.txt
@@ -385,20 +385,20 @@ polyhedral surface gives alias names renaming face to facet.
 
 class Polyhedron_items_3 {
 public:
-template < class Refs, class Traits>
-struct Vertex_wrapper {
-typedef typename Traits::Point_3 Point;
-typedef CGAL::HalfedgeDS_vertex_base<Refs, CGAL::Tag_true, Point> Vertex;
-};
-template < class Refs, class Traits>
-struct Halfedge_wrapper {
-typedef CGAL::HalfedgeDS_halfedge_base<Refs> Halfedge;
-};
-template < class Refs, class Traits>
-struct Face_wrapper {
-typedef typename Traits::Plane_3 Plane;
-typedef CGAL::HalfedgeDS_face_base<Refs, CGAL::Tag_true, Plane> Face;
-};
+  template < class Refs, class Traits>
+  struct Vertex_wrapper {
+    typedef typename Traits::Point_3 Point;
+    typedef CGAL::HalfedgeDS_vertex_base<Refs, CGAL::Tag_true, Point> Vertex;
+  };
+  template < class Refs, class Traits>
+  struct Halfedge_wrapper {
+    typedef CGAL::HalfedgeDS_halfedge_base<Refs> Halfedge;
+  };
+  template < class Refs, class Traits>
+  struct Face_wrapper {
+    typedef typename Traits::Plane_3 Plane;
+    typedef CGAL::HalfedgeDS_face_base<Refs, CGAL::Tag_true, Plane> Face;
+  };
 };
 
 \endcode
@@ -426,7 +426,7 @@ faces but would be for vertices - and add the color attribute.
 
 template <class Refs>
 struct My_face : public CGAL::HalfedgeDS_face_base<Refs> {
-CGAL::IO::Color color;
+  CGAL::IO::Color color;
 };
 
 \endcode
@@ -440,10 +440,10 @@ used.
 \code{.cpp}
 
 struct My_items : public CGAL::Polyhedron_items_3 {
-template <class Refs, class Traits>
-struct Face_wrapper {
-typedef My_face<Refs> Face;
-};
+  template <class Refs, class Traits>
+  struct Face_wrapper {
+    typedef My_face<Refs> Face;
+  };
 };
 
 \endcode
@@ -479,8 +479,8 @@ works as illustrated above.
 
 template <class Refs>
 struct My_face : public CGAL::HalfedgeDS_face_base<Refs> {
-typedef typename Refs::Vertex_handle Vertex_handle;
-Vertex_handle vertex_ref;
+  typedef typename Refs::Vertex_handle Vertex_handle;
+  Vertex_handle vertex_ref;
 };
 
 \endcode
diff --git a/Surface_mesh_shortest_path/examples/Surface_mesh_shortest_path/shortest_paths_multiple_sources.cpp b/Surface_mesh_shortest_path/examples/Surface_mesh_shortest_path/shortest_paths_multiple_sources.cpp
index 4b1a99fabbd..a0a05111c91 100644
--- a/Surface_mesh_shortest_path/examples/Surface_mesh_shortest_path/shortest_paths_multiple_sources.cpp
+++ b/Surface_mesh_shortest_path/examples/Surface_mesh_shortest_path/shortest_paths_multiple_sources.cpp
@@ -6,7 +6,6 @@
 
 #include <boost/lexical_cast.hpp>
 
-#include <cstdlib>
 #include <cstdlib>
 #include <iostream>
 #include <fstream>
diff --git a/Surface_mesh_simplification/include/CGAL/Surface_mesh_simplification/internal/Common.h b/Surface_mesh_simplification/include/CGAL/Surface_mesh_simplification/internal/Common.h
index 4ed45a02d1e..2d3158a7095 100644
--- a/Surface_mesh_simplification/include/CGAL/Surface_mesh_simplification/internal/Common.h
+++ b/Surface_mesh_simplification/include/CGAL/Surface_mesh_simplification/internal/Common.h
@@ -29,7 +29,6 @@
 #include <functional>
 #include <utility>
 #include <vector>
-#include <vector>
 #include <set>
 
 namespace CGAL {
diff --git a/Triangulation_2/doc/Triangulation_2/Concepts/DelaunayTriangulationTraits_2.h b/Triangulation_2/doc/Triangulation_2/Concepts/DelaunayTriangulationTraits_2.h
index f76e24c327a..0ec0e42e70d 100644
--- a/Triangulation_2/doc/Triangulation_2/Concepts/DelaunayTriangulationTraits_2.h
+++ b/Triangulation_2/doc/Triangulation_2/Concepts/DelaunayTriangulationTraits_2.h
@@ -26,7 +26,6 @@ required if the  method `nearest_vertex()` is used.
 \cgalHasModelsBare{All models of the \cgal concept `Kernel`}
 \cgalHasModelsBare{`CGAL::Projection_traits_3<K>` (not for dual Voronoi functions)}
 \cgalHasModelsBare{`CGAL::Projection_traits_xy_3<K>` (not for dual Voronoi functions)}
-\cgalHasModelsBare{`CGAL::Projection_traits_xy_3<K>` (not for dual Voronoi functions)}
 \cgalHasModelsBare{`CGAL::Projection_traits_yz_3<K>` (not for dual Voronoi functions)}
 \cgalHasModelsBare{`CGAL::Projection_traits_xz_3<K>` (not for dual Voronoi functions)}
 \cgalHasModelsEnd
diff --git a/Triangulation_2/include/CGAL/Triangulation_2/insert_constraints.h b/Triangulation_2/include/CGAL/Triangulation_2/insert_constraints.h
index dc08e642db7..9fbd223ac25 100644
--- a/Triangulation_2/include/CGAL/Triangulation_2/insert_constraints.h
+++ b/Triangulation_2/include/CGAL/Triangulation_2/insert_constraints.h
@@ -84,7 +84,6 @@ namespace CGAL {
                                    ConstraintIterator first,
                                    ConstraintIterator beyond)
   {
-    typedef typename T::Point Point;
     typedef typename T::Point Point;
     std::vector<Point> points;
     for (ConstraintIterator s_it=first; s_it!=beyond; ++s_it)