Kernel_23: Fix Issue 8140

Filtered_kernel/include/CGAL/Lazy_kernel.h

@@ -280,12 +280,18 @@ class Lazy_kernel_generic_base : protected internal::Enum_holder
   C Cf() const { return C(); }
 
 #include <CGAL/Kernel/interface_macros.h>
+
+  // Useless meta-function, added to workaround a bug with Visual C++ 2022 and before
+  // See issue https://github.com/CGAL/cgal/issues/8140
+  template < typename T >
+  struct Handle { typedef T   type; };
 };
 
 
 
 
 
+
 template < typename EK_, typename AK_, typename E2A_, typename Kernel_ >
 class Lazy_kernel_base
   : public Lazy_kernel_generic_base<EK_, AK_, E2A_, Kernel_>

Kernel_23/test/Kernel_23/CMakeLists.txt

@@ -14,6 +14,7 @@ create_single_source_cgal_program("Filtered_homogeneous.cpp")
 create_single_source_cgal_program("Homogeneous.cpp")
 create_single_source_cgal_program("issue_129.cpp")
 create_single_source_cgal_program("issue_3301.cpp")
+create_single_source_cgal_program("issue_8140.cpp")
 create_single_source_cgal_program("Kernel_checker.cpp")
 create_single_source_cgal_program("Lazy_kernel.cpp")
 create_single_source_cgal_program("origin_3.cpp")

Kernel_23/test/Kernel_23/issue_8140.cpp

@@ -0,0 +1,12 @@
+#include <CGAL/Exact_predicates_exact_constructions_kernel.h>
+
+int main() { // For testing, we just print the combinations of types
+  using Kernel = CGAL::Exact_predicates_exact_constructions_kernel;
+  using Vec_3 = Kernel::Vector_3;
+  using Cp_fnc3 = Vec_3(*)(const Vec_3&, const Vec_3&);
+
+  Cp_fnc3 f = static_cast<Cp_fnc3>(&CGAL::cross_product<Kernel>);
+  Vec_3 v1, v2;
+  Vec_3 v = f(v1, v2);
+  return 0;
+}