compiles on mac

include/igl/copyleft/cgal/mesh_to_polyhedron.cpp

@@ -52,4 +52,6 @@ IGL_INLINE bool igl::copyleft::cgal::mesh_to_polyhedron(
 // Explicit template instantiation
 #include <CGAL/Simple_cartesian.h>
 #include <CGAL/Polyhedron_items_with_id_3.h>
+#include <CGAL/Polyhedron_3.h>
+template bool igl::copyleft::cgal::mesh_to_polyhedron<Eigen::Matrix<double, -1, -1, 0, -1, -1>, Eigen::Matrix<int, -1, -1, 0, -1, -1>, CGAL::Polyhedron_3<CGAL::Simple_cartesian<double>, CGAL::Polyhedron_items_with_id_3, CGAL::HalfedgeDS_default, std::__1::allocator<int> > >(Eigen::MatrixBase<Eigen::Matrix<double, -1, -1, 0, -1, -1> > const&, Eigen::MatrixBase<Eigen::Matrix<int, -1, -1, 0, -1, -1> > const&, CGAL::Polyhedron_3<CGAL::Simple_cartesian<double>, CGAL::Polyhedron_items_with_id_3, CGAL::HalfedgeDS_default, std::__1::allocator<int> >&);
 #endif

tests/include/igl/copyleft/cgal/mesh_to_polyhedron.cpp

@@ -1,6 +1,7 @@
 #include <test_common.h>
 #include <igl/copyleft/cgal/mesh_to_polyhedron.h>
 #include <CGAL/Simple_cartesian.h>
+#include <CGAL/Polyhedron_3.h>
 #include <CGAL/Polyhedron_items_with_id_3.h>
 
 TEST_CASE(