add a small example showing the overload problem when result_type

is defined in Null_functor

.gitattributes

@@ -1843,6 +1843,7 @@ Kernel_23/examples/Kernel_23/cartesian_converter.cpp -text
 Kernel_23/include/CGAL/functions_on_enums.h -text
 Kernel_23/include/CGAL/internal/Projection_traits_3.h -text
 Kernel_23/test/Kernel_23/CMakeLists.txt -text
+Kernel_23/test/Kernel_23/overload_bug.cpp -text
 Kernel_d/doc_tex/Kernel_d/hypercube.png -text
 Kernel_d/doc_tex/Kernel_d_ref/Kernel_Compute_coordinate_d.tex -text
 Kernel_d/doc_tex/Kernel_d_ref/Kernel_Less_coordinate_d.tex -text

Kernel_23/test/Kernel_23/CMakeLists.txt

@@ -33,5 +33,5 @@ if ( CGAL_FOUND )
   create_single_source_cgal_program( Simple_cartesian.cpp )
   create_single_source_cgal_program( Simple_homogeneous.cpp )
   create_single_source_cgal_program( test_kernel__.cpp )
-
+  create_single_source_cgal_program( overload_bug.cpp )
 endif()

Kernel_23/test/Kernel_23/overload_bug.cpp

@@ -0,0 +1,17 @@
+#include <CGAL/Simple_cartesian.h>
+#include <CGAL/intersection_2.h>
+typedef CGAL::Simple_cartesian<double> Kernel;
+typedef Kernel::Point_2 Point_2;
+
+struct Segment_2D : public CGAL::Segment_2<Kernel>
+{
+  Segment_2D(const ::Point_2 &p,
+             const ::Point_2 &q) : CGAL::Segment_2<Kernel>(p, q) {}
+};
+
+int main(){
+  Segment_2D s1(Point_2(0,0),Point_2(1,0));
+  Segment_2D s2(Point_2(0,0),Point_2(0,1));
+  CGAL::intersection(s1,s2);
+  
+}