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

26 Feb 2008


      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 
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