diff --git a/Arrangement_on_surface_2/include/CGAL/Arr_bounded_planar_topology_traits_2.h b/Arrangement_on_surface_2/include/CGAL/Arr_bounded_planar_topology_traits_2.h
index 23caa591c00..e1582795054 100644
--- a/Arrangement_on_surface_2/include/CGAL/Arr_bounded_planar_topology_traits_2.h
+++ b/Arrangement_on_surface_2/include/CGAL/Arr_bounded_planar_topology_traits_2.h
@@ -90,10 +90,10 @@ public:
   typedef typename Gt_adaptor_2::Top_side_category    Top_side_category;
   typedef typename Gt_adaptor_2::Right_side_category  Right_side_category;
 
-  CGAL_static_assertion(std::is_same< Left_side_category, Arr_oblivious_side_tag >::value);
-  CGAL_static_assertion(std::is_same< Bottom_side_category, Arr_oblivious_side_tag >::value);
-  CGAL_static_assertion(std::is_same< Top_side_category, Arr_oblivious_side_tag >::value);
-  CGAL_static_assertion(std::is_same< Right_side_category, Arr_oblivious_side_tag >::value);
+  CGAL_static_assertion((std::is_same< Left_side_category, Arr_oblivious_side_tag >::value));
+  CGAL_static_assertion((std::is_same< Bottom_side_category, Arr_oblivious_side_tag >::value));
+  CGAL_static_assertion((std::is_same< Top_side_category, Arr_oblivious_side_tag >::value));
+  CGAL_static_assertion((std::is_same< Right_side_category, Arr_oblivious_side_tag >::value));
   //@}
 
   /*! \struct
diff --git a/Arrangement_on_surface_2/include/CGAL/Arr_spherical_topology_traits_2.h b/Arrangement_on_surface_2/include/CGAL/Arr_spherical_topology_traits_2.h
index b55a01b016c..6965f66e99f 100644
--- a/Arrangement_on_surface_2/include/CGAL/Arr_spherical_topology_traits_2.h
+++ b/Arrangement_on_surface_2/include/CGAL/Arr_spherical_topology_traits_2.h
@@ -91,14 +91,14 @@ public:
   typedef typename Gt_adaptor_2::Top_side_category    Top_side_category;
   typedef typename Gt_adaptor_2::Right_side_category  Right_side_category;
 
-  CGAL_static_assertion(std::is_same< Left_side_category, Arr_oblivious_side_tag >::value ||
-                        std::is_same< Left_side_category, Arr_identified_side_tag >::value);
-  CGAL_static_assertion(std::is_same< Bottom_side_category, Arr_oblivious_side_tag >::value ||
-                        std::is_same< Bottom_side_category, Arr_contracted_side_tag >::value);
-  CGAL_static_assertion(std::is_same< Top_side_category, Arr_oblivious_side_tag >::value ||
-                        std::is_same< Top_side_category, Arr_contracted_side_tag >::value);
-  CGAL_static_assertion(std::is_same< Right_side_category, Arr_oblivious_side_tag >::value ||
-                        std::is_same< Right_side_category, Arr_identified_side_tag >::value);
+  CGAL_static_assertion((std::is_same< Left_side_category, Arr_oblivious_side_tag >::value ||
+                         std::is_same< Left_side_category, Arr_identified_side_tag >::value));
+  CGAL_static_assertion((std::is_same< Bottom_side_category, Arr_oblivious_side_tag >::value ||
+                         std::is_same< Bottom_side_category, Arr_contracted_side_tag >::value));
+  CGAL_static_assertion((std::is_same< Top_side_category, Arr_oblivious_side_tag >::value ||
+                         std::is_same< Top_side_category, Arr_contracted_side_tag >::value));
+  CGAL_static_assertion((std::is_same< Right_side_category, Arr_oblivious_side_tag >::value ||
+                         std::is_same< Right_side_category, Arr_identified_side_tag >::value));
   //@}
 
   /*! \struct
diff --git a/Arrangement_on_surface_2/include/CGAL/Arr_unb_planar_topology_traits_2.h b/Arrangement_on_surface_2/include/CGAL/Arr_unb_planar_topology_traits_2.h
index 8d4ac032993..355dd76641e 100644
--- a/Arrangement_on_surface_2/include/CGAL/Arr_unb_planar_topology_traits_2.h
+++ b/Arrangement_on_surface_2/include/CGAL/Arr_unb_planar_topology_traits_2.h
@@ -87,14 +87,14 @@ public:
   typedef typename Gt_adaptor_2::Top_side_category    Top_side_category;
   typedef typename Gt_adaptor_2::Right_side_category  Right_side_category;
 
-  CGAL_static_assertion(std::is_same< Left_side_category, Arr_oblivious_side_tag >::value ||
-                        std::is_same< Left_side_category, Arr_open_side_tag >::value);
-  CGAL_static_assertion(std::is_same< Bottom_side_category, Arr_oblivious_side_tag >::value ||
-                        std::is_same< Bottom_side_category, Arr_open_side_tag >::value);
-  CGAL_static_assertion(std::is_same< Top_side_category, Arr_oblivious_side_tag>::value ||
-                        std::is_same< Top_side_category, Arr_open_side_tag >::value);
-  CGAL_static_assertion(std::is_same< Right_side_category, Arr_oblivious_side_tag >::value ||
-                        std::is_same< Right_side_category, Arr_open_side_tag >::value);
+  CGAL_static_assertion((std::is_same< Left_side_category, Arr_oblivious_side_tag >::value ||
+                         std::is_same< Left_side_category, Arr_open_side_tag >::value));
+  CGAL_static_assertion((std::is_same< Bottom_side_category, Arr_oblivious_side_tag >::value ||
+                         std::is_same< Bottom_side_category, Arr_open_side_tag >::value));
+  CGAL_static_assertion((std::is_same< Top_side_category, Arr_oblivious_side_tag>::value ||
+                         std::is_same< Top_side_category, Arr_open_side_tag >::value));
+  CGAL_static_assertion((std::is_same< Right_side_category, Arr_oblivious_side_tag >::value ||
+                         std::is_same< Right_side_category, Arr_open_side_tag >::value));
   //@}
 
   /*! \struct
diff --git a/Arrangement_on_surface_2/include/CGAL/Arrangement_on_surface_2.h b/Arrangement_on_surface_2/include/CGAL/Arrangement_on_surface_2.h
index 88a47dd3a17..4e576f928a1 100644
--- a/Arrangement_on_surface_2/include/CGAL/Arrangement_on_surface_2.h
+++ b/Arrangement_on_surface_2/include/CGAL/Arrangement_on_surface_2.h
@@ -79,10 +79,10 @@ public:
   typedef typename Traits_adaptor_2::Top_side_category    Top_side_category;
   typedef typename Traits_adaptor_2::Right_side_category  Right_side_category;
 
-  CGAL_static_assertion(Arr_sane_identified_tagging<Left_side_category,
+  CGAL_static_assertion((Arr_sane_identified_tagging<Left_side_category,
                         Bottom_side_category,
                         Top_side_category,
-                        Right_side_category>::value);
+                        Right_side_category>::value));
 
 public:
   typedef Arrangement_on_surface_2<Geometry_traits_2, Topology_traits>
diff --git a/Arrangement_on_surface_2/include/CGAL/Arrangement_zone_2.h b/Arrangement_on_surface_2/include/CGAL/Arrangement_zone_2.h
index 7f99e1d822c..8f3df2766c0 100644
--- a/Arrangement_on_surface_2/include/CGAL/Arrangement_zone_2.h
+++ b/Arrangement_on_surface_2/include/CGAL/Arrangement_zone_2.h
@@ -67,10 +67,10 @@ protected:
   typedef typename Traits_adaptor_2::Top_side_category    Top_side_category;
   typedef typename Traits_adaptor_2::Right_side_category  Right_side_category;
 
-  CGAL_static_assertion(Arr_sane_identified_tagging<Left_side_category,
+  CGAL_static_assertion((Arr_sane_identified_tagging<Left_side_category,
                                                     Bottom_side_category,
                                                     Top_side_category,
-                                                    Right_side_category>::value);
+                                                    Right_side_category>::value));
 
 public:
   typedef ZoneVisitor_                                   Visitor;
diff --git a/Boolean_set_operations_2/include/CGAL/Boolean_set_operations_2/Gps_agg_meta_traits.h b/Boolean_set_operations_2/include/CGAL/Boolean_set_operations_2/Gps_agg_meta_traits.h
index f6071e12ed9..f673515eda6 100644
--- a/Boolean_set_operations_2/include/CGAL/Boolean_set_operations_2/Gps_agg_meta_traits.h
+++ b/Boolean_set_operations_2/include/CGAL/Boolean_set_operations_2/Gps_agg_meta_traits.h
@@ -123,14 +123,14 @@ public:
   typedef typename Arr::Right_side_category     Right_side_category;
 
   // a side is either oblivious or open (unbounded)
-  CGAL_static_assertion(std::is_same<Left_side_category, Arr_oblivious_side_tag>::value ||
-                        std::is_same<Left_side_category, Arr_open_side_tag>::value);
-  CGAL_static_assertion(std::is_same<Bottom_side_category, Arr_oblivious_side_tag>::value ||
-                        std::is_same<Bottom_side_category, Arr_open_side_tag>::value);
-  CGAL_static_assertion(std::is_same<Top_side_category, Arr_oblivious_side_tag>::value ||
-                        std::is_same<Top_side_category, Arr_open_side_tag> >::value);
-  CGAL_static_assertion(std::is_same<Right_side_category, Arr_oblivious_side_tag>::value ||
-                        std::is_same<Right_side_category, Arr_open_side_tag>::value);
+  CGAL_static_assertion((std::is_same<Left_side_category, Arr_oblivious_side_tag>::value ||
+                         std::is_same<Left_side_category, Arr_open_side_tag>::value));
+  CGAL_static_assertion((std::is_same<Bottom_side_category, Arr_oblivious_side_tag>::value ||
+                         std::is_same<Bottom_side_category, Arr_open_side_tag>::value));
+  CGAL_static_assertion((std::is_same<Top_side_category, Arr_oblivious_side_tag>::value ||
+                         std::is_same<Top_side_category, Arr_open_side_tag>::value));
+  CGAL_static_assertion((std::is_same<Right_side_category, Arr_oblivious_side_tag>::value ||
+                         std::is_same<Right_side_category, Arr_open_side_tag>::value));
 
   typedef typename Arr::Halfedge_handle         Halfedge_handle;
   typedef typename Arr::Vertex_handle           Vertex_handle;
diff --git a/Boolean_set_operations_2/include/CGAL/Boolean_set_operations_2/Gps_traits_decorator.h b/Boolean_set_operations_2/include/CGAL/Boolean_set_operations_2/Gps_traits_decorator.h
index 3a1f3c552e8..c260e4cf824 100644
--- a/Boolean_set_operations_2/include/CGAL/Boolean_set_operations_2/Gps_traits_decorator.h
+++ b/Boolean_set_operations_2/include/CGAL/Boolean_set_operations_2/Gps_traits_decorator.h
@@ -53,14 +53,14 @@ public:
   typedef typename Base::Right_side_category       Right_side_category;
 
   // a side is either oblivious or open (unbounded)
-  CGAL_static_assertion(std::is_same< Left_side_category, Arr_oblivious_side_tag >::value ||
-                        std::is_same< Left_side_category, Arr_open_side_tag >::value);
-  CGAL_static_assertion(std::is_same< Bottom_side_category, Arr_oblivious_side_tag >::value ||
-                        std::is_same< Bottom_side_category, Arr_open_side_tag >::value);
-  CGAL_static_assertion(std::is_same< Top_side_category, Arr_oblivious_side_tag >::value ||
-                        std::is_same< Top_side_category, Arr_open_side_tag > >::value);
-  CGAL_static_assertion(std::is_same< Right_side_category, Arr_oblivious_side_tag >::value ||
-                        std::is_same< Right_side_category, Arr_open_side_tag > >::value);
+  CGAL_static_assertion((std::is_same< Left_side_category, Arr_oblivious_side_tag >::value ||
+                         std::is_same< Left_side_category, Arr_open_side_tag >::value));
+  CGAL_static_assertion((std::is_same< Bottom_side_category, Arr_oblivious_side_tag >::value ||
+                         std::is_same< Bottom_side_category, Arr_open_side_tag >::value));
+  CGAL_static_assertion((std::is_same< Top_side_category, Arr_oblivious_side_tag >::value ||
+                         std::is_same< Top_side_category, Arr_open_side_tag >::value));
+  CGAL_static_assertion((std::is_same< Right_side_category, Arr_oblivious_side_tag >::value ||
+                         std::is_same< Right_side_category, Arr_open_side_tag >::value));
 
   class Ex_point_2
   {
diff --git a/Interpolation/include/CGAL/regular_neighbor_coordinates_2.h b/Interpolation/include/CGAL/regular_neighbor_coordinates_2.h
index 5f8f93aa1e1..050e86d7fa0 100644
--- a/Interpolation/include/CGAL/regular_neighbor_coordinates_2.h
+++ b/Interpolation/include/CGAL/regular_neighbor_coordinates_2.h
@@ -329,7 +329,7 @@ regular_neighbor_coordinates_2(const Rt& rt,
                                typename Rt::Face_handle start,
                                std::enable_if_t<
                                           !is_iterator_v<OutputFunctor>
-                                        >::type* = 0)
+                                        >* = 0)
 {
   return regular_neighbor_coordinates_2(rt, p, out, fct, Emptyset_iterator(), start);
 }
@@ -342,7 +342,7 @@ regular_neighbor_coordinates_2(const Rt& rt,
                                const typename Rt::Weighted_point& p,
                                OutputIterator out,
                                OutputFunctor fct,
-                               std::enable_if_c<
+                               std::enable_if_t<
                                  !boost::is_convertible<OutputFunctor,
                                                        typename Rt::Face_handle>::value
                                >* = 0)
@@ -424,7 +424,7 @@ regular_neighbor_coordinates_2(const Rt& rt,
                                EdgeIterator hole_end,
                                VertexIterator hidden_vertices_begin,
                                VertexIterator hidden_vertices_end,
-                               std::enable_if_t!<
+                               std::enable_if_t<
                                           !is_iterator_v<OutputFunctor>
                                         >* = 0)
 {
diff --git a/NewKernel_d/include/CGAL/NewKernel_d/Wrapper/Sphere_d.h b/NewKernel_d/include/CGAL/NewKernel_d/Wrapper/Sphere_d.h
index f519f34ff14..7bcd8568dcc 100644
--- a/NewKernel_d/include/CGAL/NewKernel_d/Wrapper/Sphere_d.h
+++ b/NewKernel_d/include/CGAL/NewKernel_d/Wrapper/Sphere_d.h
@@ -54,7 +54,7 @@ public:
 
   typedef          R_                       R;
 
-  template<class...U,class=std::enable_if_t<!std::is_same<std::tuple<typename std::decay<U>::type...>::value,std::tuple<Sphere_d> >::value>> explicit Sphere_d(U&&...u)
+  template<class...U,class=typename std::enable_if_t<!std::is_same<std::tuple<typename std::decay<U>::type...>,std::tuple<Sphere_d> >::value>> explicit Sphere_d(U&&...u)
           : Rep(CSBase()(std::forward<U>(u)...)){}
 
 //  // called from Construct_point_d
diff --git a/Number_types/test/Number_types/checked_NT.h b/Number_types/test/Number_types/checked_NT.h
index 41d55f482b7..18acef9c220 100644
--- a/Number_types/test/Number_types/checked_NT.h
+++ b/Number_types/test/Number_types/checked_NT.h
@@ -21,8 +21,8 @@ struct checked_NT {
   checked_NT():x1(),x2(){verify();}
   checked_NT(checked_NT const&t):x1(t.x1),x2(t.x2){verify();}
   checked_NT& operator=(checked_NT const&t){x1=t.x1;x2=t.x2;verify();return *this;}
-  template<class T> checked_NT(T const&t,std::enable_if_t<is_implicit_convertible<T,NT1>::value,int>=0):x1(t),x2(t){verify();}
-  template<class T> explicit checked_NT(T const&t,std::enable_if_t<!is_implicit_convertible<T,NT1>::value,int>=0):x1(t),x2(t){verify();}
+  template<class T> checked_NT(T const&t,std::enable_if_t<is_implicit_convertible<T,NT1>::value,int> = 0):x1(t),x2(t){verify();}
+  template<class T> explicit checked_NT(T const&t,std::enable_if_t<!is_implicit_convertible<T,NT1>::value,int> = 0):x1(t),x2(t){verify();}
   /*TODO: enable_if to restrict the types*/
   template<class T> checked_NT& operator=(T const&t){x1=t;x2=t;verify();return *this;}
   checked_NT operator-()const{return checked_NT(pieces(),-x1,-x2);}
diff --git a/Polygon_mesh_processing/include/CGAL/Polygon_mesh_processing/internal/Corefinement/face_graph_utils.h b/Polygon_mesh_processing/include/CGAL/Polygon_mesh_processing/internal/Corefinement/face_graph_utils.h
index 8ac6b6ada76..66164dd27dd 100644
--- a/Polygon_mesh_processing/include/CGAL/Polygon_mesh_processing/internal/Corefinement/face_graph_utils.h
+++ b/Polygon_mesh_processing/include/CGAL/Polygon_mesh_processing/internal/Corefinement/face_graph_utils.h
@@ -399,7 +399,7 @@ struct TweakedGetVertexPointMap
 
 template <class PT, class NP, class PM>
 boost::optional< typename TweakedGetVertexPointMap<PT, NP, PM>::type >
-get_vpm(const NP& np, boost::optional<PM*> opm, boost::true_type)
+get_vpm(const NP& np, boost::optional<PM*> opm, std::true_type)
 {
   if (boost::none == opm) return boost::none;
   return parameters::choose_parameter(
@@ -409,7 +409,7 @@ get_vpm(const NP& np, boost::optional<PM*> opm, boost::true_type)
 
 template <class PT, class NP, class PM>
 boost::optional< typename TweakedGetVertexPointMap<PT, NP, PM>::type >
-get_vpm(const NP&, boost::optional<PM*> opm, boost::false_type)
+get_vpm(const NP&, boost::optional<PM*> opm, std::false_type)
 {
   if (boost::none == opm) return boost::none;
   return typename TweakedGetVertexPointMap<PT, NP, PM>::type();
diff --git a/STL_Extension/test/STL_Extension/test_Boolean_tag.cpp b/STL_Extension/test/STL_Extension/test_Boolean_tag.cpp
index 55784a0995c..90ee2479438 100644
--- a/STL_Extension/test/STL_Extension/test_Boolean_tag.cpp
+++ b/STL_Extension/test/STL_Extension/test_Boolean_tag.cpp
@@ -10,14 +10,14 @@ using CGAL::Tag_true;
 using CGAL::Tag_false;
 
 int main() {
-  CGAL_static_assertion(is_same< Tag_true::value_type, bool >::value);
-  CGAL_static_assertion(is_same< Tag_true::type, Tag_true >::value);
-  CGAL_static_assertion(Tag_true::value== true);
+  static_assert(is_same< Tag_true::value_type, bool >::value,"");
+  static_assert(is_same< Tag_true::type, Tag_true >::value,"");
+  static_assert(Tag_true::value== true,"");
   assert( Tag_true() == true );
 
-  CGAL_static_assertion(is_same< Tag_false::value_type, bool >::value);
-  CGAL_static_assertion(is_same< Tag_false::type, Tag_false >::value);
-  CGAL_static_assertion(Tag_false::value == false);
+  static_assert(is_same< Tag_false::value_type, bool >::value,"");
+  static_assert(is_same< Tag_false::type, Tag_false >::value,"");
+  static_assert(Tag_false::value == false,"");
   assert( Tag_false() == false );
 
   return 0;
diff --git a/Spatial_searching/include/CGAL/Fuzzy_iso_box.h b/Spatial_searching/include/CGAL/Fuzzy_iso_box.h
index 5941e989489..3aeaeb550e8 100644
--- a/Spatial_searching/include/CGAL/Fuzzy_iso_box.h
+++ b/Spatial_searching/include/CGAL/Fuzzy_iso_box.h
@@ -34,13 +34,15 @@ namespace CGAL {
   namespace internal{
     template <class SearchTraits,class Point>
     struct Is_from_point_from_adapter_traits{
-      typedef boost::false_type type;
+      typedef std::false_type type;
+      static const bool value = false;
     };
 
 
     template <class K,class PM,class Base,class Point>
     struct Is_from_point_from_adapter_traits<Search_traits_adapter<K,PM,Base>,Point>{
       typedef typename std::is_same<Point,typename Base::Point_d> type;
+      static const bool value = type::value;
     };
   } //namespace internal
 
diff --git a/Surface_sweep_2/include/CGAL/No_intersection_surface_sweep_2.h b/Surface_sweep_2/include/CGAL/No_intersection_surface_sweep_2.h
index 729bc1d98ba..1a55d18baa6 100644
--- a/Surface_sweep_2/include/CGAL/No_intersection_surface_sweep_2.h
+++ b/Surface_sweep_2/include/CGAL/No_intersection_surface_sweep_2.h
@@ -129,8 +129,8 @@ public:
   typedef typename Traits_adaptor_2::Top_side_category    Top_side_category;
   typedef typename Traits_adaptor_2::Right_side_category  Right_side_category;
 
-  CGAL_static_assertion(Arr_sane_identified_tagging< Left_side_category, Bottom_side_category,
-                          Top_side_category, Right_side_category >::value);
+  CGAL_static_assertion((Arr_sane_identified_tagging< Left_side_category, Bottom_side_category,
+                          Top_side_category, Right_side_category >::value));
 
 protected:
   /*!