2013/7/19 Jupp Tscheak <jupp.tscheak@gmx.de>

Hello boost users,

Please consider the following example:

[code]
#include "CGAL/Cartesian.h"
#include "CGAL/Polygon_2.h"

#include "boost/container/static_vector.hpp"

typedef CGAL::Cartesian<double> Kernel;
typedef Kernel::Point_2 Point2d;
typedef CGAL::Polygon_2<Kernel, boost::container::static_vector<Point2d, 100> > Polygon2d;

Polygon2d p;
p = Polygon2d();
[/code]

Compiling this code snippet with GCC results in following error message:

[error]
error: no match for 'operator=' in 'p = CGAL::Polygon_2<CGAL::Cartesian<double>, boost::container::static_vector<CGAL::Point_2<CGAL::Cartesian<double> >, 100u> >((*(const Traits*)(& CGAL::Polygon_2<CGAL::Cartesian<double>, boost::container::static_vector<CGAL::Point_2<CGAL::Cartesian<double> >, 100u> >::Traits())))'
note: candidate is:
CGAL-4.2/include/CGAL/Polygon_2.h:68:7: note: CGAL::Polygon_2<CGAL::Cartesian<double>, boost::container::static_vector<CGAL::Point_2<CGAL::Cartesian<double> >, 100u> >& CGAL::Polygon_2<CGAL::Cartesian<double>, boost::container::static_vector<CGAL::Point_2<CGAL::Cartesian<double> >, 100u> >::operator=(CGAL::Polygon_2<CGAL::Cartesian<double>, boost::container::static_vector<CGAL::Point_2<CGAL::Cartesian<double> >, 100u> >&)
CGAL-4.2/include/CGAL/Polygon_2.h:68:7: note: no known conversion for argument 1 from 'sensor::Polygon2d {aka CGAL::Polygon_2<CGAL::Cartesian<double>, boost::container::static_vector<CGAL::Point_2<CGAL::Cartesian<double> >, 100u> >}' to 'CGAL::Polygon_2<CGAL::Cartesian<double>, boost::container::static_vector<CGAL::Point_2<CGAL::Cartesian<double> >, 100u> >&'
[/error]

I apologize for this concrete example using CGAL, but maybe someone has advice for me?

Hello Jupp,

I don't know anything about CGAL, but I have a guess for you, where I assume you're *not* in C++11 mode. I think I saw a similar error with my structures and mingw-4.7. Please see this example (warning: it's out of my head, not tested):

struct X

{

  static_vector<int,3> v;

};

int main()

{

  X x, y;

  x = y; // similar compile error

}

 

 If you get a similar error compiling the example above, I believe I can explain it. I looks to me like the fault of move emulation in static_vector. I'm not sure if it's a bug in static_vector, or if that's the cost of using Boost.Move, but I remember writing my own operator= in struct X helped:

struct X

{

  static_vector<int,3> v;

  X& operator=( X const& x ) { v = x.v; return *this; }

};

I think this is needed, because due to using Boost.Move in emulation mode static_vector defines

static_vector& operator=(static_vector&); // note: non-const arg

so the auto-generated operaotr= in X also takes a non-const

HTH,

Kris

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