Boost.variant can not work with const rvalues

[Antony Polukhin]

Thanks to gast128! he found the following bug and reported it in mailing lists:

I get a compilation error with Boost.Variant (which compiles fine on previous releases) with vstudio 2010 when a function returns a const Boost.Variant, e.g.:

typedef boost::variant<int, double> Variant;

const Variant GetVar()
{
  return Variant();
}


void TestVariantDnc()
{
   const Variant var = GetVar();
}

This gives error C2666 ('boost::variant<T0_,T1>::convert_construct' : 3 overloads have similar conversions').

[Antony Polukhin]

(In [85315]) Fix issue with const rvalue references in Boost.Variant (refs #8988)

[Antony Polukhin]

(In [85408]) Merge from trunk:

• Fix issue with const rvalue references in Boost.Variant (fixes #8988)
• Get rid of Boost.Variant hand written non-usable move emulation and use Boost.Move instead(refs #7601). This does not mean that Boost.Variant supports move emulation now, but removes duplicate/non-working code and makes sure that Boost.Variant is able to work with boost::move