[boost] [polygon] polygon_traits.hpp is incompatible with C++17 std::size()

Subject: [boost] [polygon] polygon_traits.hpp is incompatible with C++17 std::size()
From: Stephan T. Lavavej (stl_at_[hidden])
Date: 2015-04-21 18:46:16

Hi,

While testing VC 2015 with Boost, we found that Boost.Polygon contains unqualified calls to non-member size() which are incompatible with C++17's std::size().

Specifically, lines 617 and 703 of boost\polygon\polygon_traits.hpp say:

points.reserve(size(polygon));

The argument appears to be "typedef std::list<CPoint> CPolygon;" which is why ADL is considering std::size(). (Note that VC's current lack of Expression SFINAE is not relevant here, as std::size() is viable for std::list.)

Here's the full error output (including a new shadow warning):

C:\Temp>cl /EHsc /nologo /W4 /wd4100 /MTd /I C:\Temp\boost-1.58.0\include boost_1_58_0\libs\polygon\example\gtl_custom_polygon.cpp 
gtl_custom_polygon.cpp
Unknown compiler version - please run the configure tests and report the results
c:\temp\boost-1.58.0\include\boost\polygon\detail/property_merge.hpp(286): warning C4458: declaration of 'output' hides class member
c:\temp\boost-1.58.0\include\boost\polygon\detail/property_merge.hpp(223): note: see declaration of 'boost::polygon::merge_scanline<coordinate_type,property_type,polygon_set_type,keytype>::output'
c:\temp\boost-1.58.0\include\boost\polygon\detail/property_merge.hpp(584): note: see reference to class template instantiation 'boost::polygon::merge_scanline<coordinate_type,property_type,polygon_set_type,keytype>' being compiled
c:\temp\boost-1.58.0\include\boost\polygon\polygon_traits.hpp(617): error C2668: 'boost::polygon::size': ambiguous call to overloaded function
c:\temp\boost-1.58.0\include\boost\polygon\polygon_traits.hpp(478): note: could be 'unsigned int boost::polygon::size<polygon_type>(const T &)'
        with
        [
            polygon_type=CPolygon,
            T=CPolygon
        ]
\\vcfs\builds\VS\feature_WCFB01\1457423\binaries.x86ret\inc\xutility(1347): note: or       'unsigned int std::size<polygon_type>(const _Container &)' [found using argument-dependent lookup]
        with
        [
            polygon_type=CPolygon,
            _Container=CPolygon
        ]
c:\temp\boost-1.58.0\include\boost\polygon\polygon_traits.hpp(617): note: while trying to match the argument list '(CPolygon)'
boost_1_58_0\libs\polygon\example\gtl_custom_polygon.cpp(38): note: see reference to function template instantiation 'std::list<CPoint,std::allocator<_Ty>> &boost::polygon::convolve<Polygon,CPoint>(polygon_type &,const point_type &)' being compiled
        with
        [
            _Ty=CPoint,
            Polygon=CPolygon,
            polygon_type=CPolygon,
            point_type=CPoint
        ]
boost_1_58_0\libs\polygon\example\gtl_custom_polygon.cpp(144): note: see reference to function template instantiation 'void test_polygon<CPolygon>(void)' being compiled
c:\temp\boost-1.58.0\include\boost\polygon\polygon_traits.hpp(703): error C2668: 'boost::polygon::size': ambiguous call to overloaded function
c:\temp\boost-1.58.0\include\boost\polygon\polygon_traits.hpp(478): note: could be 'unsigned int boost::polygon::size<polygon_type>(const T &)'
        with
        [
            polygon_type=CPolygon,
            T=CPolygon
        ]
\\vcfs\builds\VS\feature_WCFB01\1457423\binaries.x86ret\inc\xutility(1347): note: or       'unsigned int std::size<polygon_type>(const _Container &)' [found using argument-dependent lookup]
        with
        [
            polygon_type=CPolygon,
            _Container=CPolygon
        ]
c:\temp\boost-1.58.0\include\boost\polygon\polygon_traits.hpp(703): note: while trying to match the argument list '(CPolygon)'
boost_1_58_0\libs\polygon\example\gtl_custom_polygon.cpp(40): note: see reference to function template instantiation 'std::list<CPoint,std::allocator<_Ty>> &boost::polygon::scale_up<Polygon>(polygon_type &,boost::polygon::coordinate_traits<int>::unsigned_area_type)' being compiled
        with
        [
            _Ty=CPoint,
            Polygon=CPolygon,
            polygon_type=CPolygon
        ]

Thanks,
STL