Boost.Variant and Boost.Fusion incompatibility

[David Sankel <camior@…>]

#include <boost/variant.hpp>
#include <boost/fusion/include/vector.hpp>

struct emptyList {};

typedef boost::make_recursive_variant
  < emptyList
  , boost::fusion::vector
      < int
      , boost::recursive_variant_
      >
  >::type IntList;

const emptyList el = emptyList();
const IntList nil( el );

IntList cons( int head, IntList tail )
{
  return IntList( boost::fusion::vector<int, IntList>( head, tail ) );
}

[David Sankel <camior@…>]

I have a suspicion that the problem may have something to do with BOOST_VARIANT_RECURSIVE_VARIANT_MAX_ARITY.

I've confirmed the issue on both clang cvs and gcc 4.8.1.

[David Sankel <camior@…>]

Using std::tuple (From gcc 4.8.1) or boost::tuple instead also produces errors.

[Antony Polukhin]

The example now works on modern versions of Boost in C++11 and more modern C++ Standards: ​https://godbolt.org/z/4o1acx1o8

Added a test case to make sure that the code keeps compiling: ​https://github.com/boostorg/variant/commit/445d790b2fe81b1b3d413d2fd464fe78712d535f

I'm not planning to work on C++03 support for that case, but would be happy to review Pull Request.