standard header <memory> with mst_orient_normals.h triggers warnings in Visual Studio

[jasjuang]

Issue Details

Please see below minimal code to reproduce the problem

mycpp.cpp

#include <memory> // if I comment out this include, it compiles like usual

#pragma warning(push, 0)
#include "CGAL/Exact_predicates_inexact_constructions_kernel.h"
#include "CGAL/mst_orient_normals.h"
#include "CGAL/property_map.h"
#pragma warning(pop)

int main(){
  typedef CGAL::Simple_cartesian<double>::Point_3 Point_3;
  typedef CGAL::Simple_cartesian<double>::Vector_3 Normal_3;
  typedef std::pair<Point_3, Normal_3> PointVectorPair;

  std::vector<PointVectorPair> pts;
    
  const int num_neigh = 18;

  CGAL::mst_orient_normals(
      pts,
      num_neigh,
      CGAL::parameters::point_map(CGAL::First_of_pair_property_map<PointVectorPair>()).
      normal_map(CGAL::Second_of_pair_property_map<PointVectorPair>()));

  return 0;
}

CMakeLists.txt

cmake_minimum_required(VERSION 3.11)

set(CMAKE_TOOLCHAIN_FILE
    $ENV{VCPKG_ROOT}/scripts/buildsystems/vcpkg.cmake
    CACHE STRING "")
set(VCPKG_TARGET_TRIPLET $ENV{VCPKG_DEFAULT_TRIPLET} CACHE STRING "")

project(Example)

set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} /WX /W4")

set(PROJECT_SRCS ${PROJECT_SOURCE_DIR}/mycpp.cpp)

find_package(CGAL REQUIRED)

add_executable(${PROJECT_NAME} ${PROJECT_SRCS})

target_link_libraries(${PROJECT_NAME} CGAL::CGAL)

and cgal is installed via vcpkg install cgal

For some reason, if I include the standard header <memory> along with mst_orient_normals.h, I will get warnings from the compiler as shown below, but if I don't include <memory> everything works like usual.

1>mycpp.cpp
1>C:\Program Files (x86)\Microsoft Visual Studio\2017\Community\VC\Tools\MSVC\14.16.27023\include\xutility(2903): error C2220: warning treated as error - no 'object' file generated
1>C:\Program Files (x86)\Microsoft Visual Studio\2017\Community\VC\Tools\MSVC\14.16.27023\include\xutility(2917): note: see reference to function template instantiation 'void std::_Fill_unchecked1<_FwdIt,_Ty>(_FwdIt,_FwdIt,const _Ty &,std::false_type)' being compiled
1>        with
1>        [
1>            _FwdIt=unsigned char *,
1>            _Ty=int
1>        ]
1>C:\Program Files (x86)\Microsoft Visual Studio\2017\Community\VC\Tools\MSVC\14.16.27023\include\xutility(2925): note: see reference to function template instantiation 'void std::_Fill_unchecked<_Ty*,int>(_FwdIt,_FwdIt,const int &)' being compiled
1>        with
1>        [
1>            _Ty=unsigned char,
1>            _FwdIt=unsigned char *
1>        ]
1>C:\dev\vcpkg\installed\x64-windows-dev\include\boost/graph/two_bit_color_map.hpp(61): note: see reference to function template instantiation 'void std::fill<T*,int>(_FwdIt,_FwdIt,const _Ty &)' being compiled
1>        with
1>        [
1>            T=unsigned char,
1>            _FwdIt=unsigned char *,
1>            _Ty=int
1>        ]
1>C:\dev\vcpkg\installed\x64-windows-dev\include\boost/graph/two_bit_color_map.hpp(57): note: while compiling class template member function 'boost::two_bit_color_map<boost::vec_adj_list_vertex_id_map<Property,unsigned __int64>>::two_bit_color_map(size_t,const IndexMap &)'
1>        with
1>        [
1>            Property=CGAL::internal::MST_graph_vertex_properties<std::_Vector_iterator<std::_Vector_val<std::_Simple_types<PointVectorPair>>>>,
1>            IndexMap=boost::vec_adj_list_vertex_id_map<CGAL::internal::MST_graph_vertex_properties<std::_Vector_iterator<std::_Vector_val<std::_Simple_types<PointVectorPair>>>>,unsigned __int64>
1>        ]
1>C:\dev\vcpkg\installed\x64-windows-dev\include\boost/graph/two_bit_color_map.hpp(100): note: see reference to function template instantiation 'boost::two_bit_color_map<boost::vec_adj_list_vertex_id_map<Property,unsigned __int64>>::two_bit_color_map(size_t,const IndexMap &)' being compiled
1>        with
1>        [
1>            Property=CGAL::internal::MST_graph_vertex_properties<std::_Vector_iterator<std::_Vector_val<std::_Simple_types<PointVectorPair>>>>,
1>            IndexMap=boost::vec_adj_list_vertex_id_map<CGAL::internal::MST_graph_vertex_properties<std::_Vector_iterator<std::_Vector_val<std::_Simple_types<PointVectorPair>>>>,unsigned __int64>
1>        ]
1>C:\dev\vcpkg\installed\x64-windows-dev\include\boost/graph/breadth_first_search.hpp(317): note: see reference to class template instantiation 'boost::two_bit_color_map<boost::vec_adj_list_vertex_id_map<Property,unsigned __int64>>' being compiled
1>        with
1>        [
1>            Property=CGAL::internal::MST_graph_vertex_properties<std::_Vector_iterator<std::_Vector_val<std::_Simple_types<PointVectorPair>>>>
1>        ]
1>C:\dev\vcpkg\installed\x64-windows-dev\include\boost/graph/breadth_first_search.hpp(345): note: see reference to function template instantiation 'void boost::detail::bfs_dispatch<boost::param_not_found>::apply<VertexListGraph,boost::bfs_visitor<CGAL::internal::Propagate_normal_orientation<std::_Vector_iterator<std::_Vector_val<std::_Simple_types<_Ty>>>,NormalMap,Kernel>>,boost::graph_visitor_t,boost::no_property>(VertexListGraph &,unsigned __int64,const boost::bgl_named_params<boost::bfs_visitor<CGAL::internal::Propagate_normal_orientation<std::_Vector_iterator<std::_Vector_val<std::_Simple_types<_Ty>>>,NormalMap,Kernel>>,boost::graph_visitor_t,boost::no_property> &,boost::param_not_found)' being compiled
1>        with
1>        [
1>            VertexListGraph=MST_graph,
1>            _Ty=PointVectorPair
1>        ]
1>C:\dev\vcpkg\installed\x64-windows-dev\include\CGAL/mst_orient_normals.h(706): note: see reference to function template instantiation 'void boost::breadth_first_search<MST_graph,boost::bfs_visitor<CGAL::internal::Propagate_normal_orientation<std::_Vector_iterator<std::_Vector_val<std::_Simple_types<_Ty>>>,NormalMap,Kernel>>,boost::graph_visitor_t,boost::no_property>(const VertexListGraph &,unsigned __int64,const boost::bgl_named_params<boost::bfs_visitor<CGAL::internal::Propagate_normal_orientation<std::_Vector_iterator<std::_Vector_val<std::_Simple_types<_Ty>>>,NormalMap,Kernel>>,boost::graph_visitor_t,boost::no_property> &)' being compiled
1>        with
1>        [
1>            _Ty=PointVectorPair,
1>            VertexListGraph=MST_graph
1>        ]
1>C:\Users\jasju\Desktop\test\mycpp.cpp(22): note: see reference to function template instantiation 'std::_Vector_iterator<std::_Vector_val<std::_Simple_types<_Ty>>> CGAL::mst_orient_normals<std::vector<_Ty,std::allocator<_Ty>>,CGAL::cgal_bgl_named_params<CGAL::Second_of_pair_property_map<PointVectorPair>,CGAL::internal_np::normal_t,CGAL::cgal_bgl_named_params<CGAL::First_of_pair_property_map<PointVectorPair>,CGAL::internal_np::point_t,boost::no_property>>>(PointRange &,unsigned int,const NamedParameters &)' being compiled
1>        with
1>        [
1>            _Ty=PointVectorPair,
1>            PointRange=std::vector<PointVectorPair,std::allocator<PointVectorPair>>,
1>            NamedParameters=CGAL::cgal_bgl_named_params<CGAL::Second_of_pair_property_map<PointVectorPair>,CGAL::internal_np::normal_t,CGAL::cgal_bgl_named_params<CGAL::First_of_pair_property_map<PointVectorPair>,CGAL::internal_np::point_t,boost::no_property>>
1>        ]
1>C:\Program Files (x86)\Microsoft Visual Studio\2017\Community\VC\Tools\MSVC\14.16.27023\include\xutility(2903): warning C4244: '=': conversion from 'const _Ty' to '_Ty', possible loss of data
1>        with
1>        [
1>            _Ty=int
1>        ]
1>        and
1>        [
1>            _Ty=unsigned char
1>        ]
1>Done building project "Example.vcxproj" -- FAILED.

Am I missing a casting for one of the parameters to CGAL::mst_orient_normals? If not, is it a bug in CGAL? Or is the bug in Visual Studio compiler? I find it bizarre that there's some conflict between <memory> and mst_orient_normals.h exclusively in Visual Studio.

Environment

• Operating system (Windows/Mac/Linux, 32/64 bits): Windows 10
• Compiler: Visual Studio 2017 (latest 15.9.5)
• Release or debug mode: Release
• CGAL version: 4.14
• Boost version: 1.70

[afabri]

The warning comes from boost, so it is not our "fault". As the compiler stack trace shows it is the call to std::fill(...., 0) which triggers the warning.

If in boost/graph/two_bit_color_map.hpp(61) you replace 0 with (unsigned char)0 the warning goes away.

[sloriot]

@afabri are you planning to do a workaround? If not we should close the issue.