Re: [Boost-users] [boost-users][Container] Compilation error using new "static_vector".

Subject: Re: [Boost-users] [boost-users][Container] Compilation error using new "static_vector".
From: Jupp Tscheak (jupp.tscheak_at_[hidden])
Date: 2013-07-20 06:35:21

Hello Kris,

Thank you very much for your assistance. 

I will give it try, although this issue became somehow obsolete since I wanted to store the "CGAL::Polygon_2" in shared memory. I noticed that this is not even possible with CGAL::Vector_2, so I have to think about something completely different.

Many thanks and best regards

Jupp Tscheak

Am 19.07.2013 um 21:52 schrieb Krzysztof Czainski:

> 2013/7/19 Jupp Tscheak <jupp.tscheak_at_[hidden]>
> 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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