CGAL users discussion list

[Philipp Moeller <>]

Marc Mörig 
<>
 writes:

> Dear CGAL maintainers,
>
> for comparison purposes I use the following combination of
> kernels/traits to compute arrangements of circles:
>
> typedef CGAL::Exact_predicates_exact_constructions_kernel Linear_k;
> typedef Linear_k::FT                                      NT;
> typedef CGAL::Algebraic_kernel_for_circles_2_2<NT>        Algebraic_k;
> typedef CGAL::Circular_kernel_2<Linear_k,Algebraic_k>     Circular_k;
> typedef CGAL::Arr_circular_line_arc_traits_2<Circular_k>  Traits;
>
> The compiler warns about returning temporaries by reference in several
> places, eg
>
> /scratch/LIBS/CGAL/CGAL-4.0.2/include/CGAL/Circle_2.h:107:55: warning:
> returning reference to temporary [enabled by default]
>
> In this and other places, there is a Qualified_result_of mechanism
> which seems to be not working, while in other places there is not. If
> I modify CGAL code to return by value in all places the compiler warns
> about I get working code. This may however result in inefficiencies
> for
> other use cases.

Which CGAL version are you using? Qualified_result_of has been removed
in CGAL 4.1.