Re: [Boost-users] [variant] make_recursive_variant containing a variant ?

From: Steven Watanabe (watanabesj_at_[hidden])
Date: 2008-02-26 15:20:03

AMDG

Alban Linard wrote:
> Hi,
>
> i am trying to build a recursive variant containing another variant, as 
> described in the following source code:
>
> #include <cstdlib>
> #include <vector>
> #include <string>
> #include <boost/variant.hpp>
>
> typedef ::boost::variant
>          < int
>          , bool
>          >
>          first_variant;
>
> typedef ::boost::make_recursive_variant
>          < first_variant
>          , ::std::string
>          , ::std::vector< ::boost::recursive_variant_ >
>          >::type
>          second_variant;
>
> int main()
> {
>    first_variant f(true);
>    second_variant s(f);
>    return EXIT_SUCCESS;
> }
>
> It does not compile (g++-4.0 and g++-4.3). It seems that the 
> "first_variant" part of second_variant is not used.
> Why this behavior ? Is there a workaround ?
>   

This is a bug in boost::variant.  You can fix it by changing line 101 of 
boost/variant/recursive_variant.hpp
from
    typedef ::boost::variant< types > type;
to
    typedef ::boost::variant< over_sequence<types> > type;

In Christ,
Steven Watanabe