Boost Spirit: call of 'swap' is ambiguous

[hannes@…]

I tried to compile a code with boost 1.58 and received the error below. The same code compiles with boost 1.55.

Error: /usr/include/boost/spirit/home/support/attributes.hpp:1036:13: error: call of overloaded ‘swap(boost::fusion::vector3<boost::shared_ptr<insight::cad::Scalar>, boost::shared_ptr<insight::cad::Scalar>, boost::shared_ptr<insight::cad::Scalar> >&, boost::fusion::vector3<boost::shared_ptr<insight::cad::Scalar>, boost::shared_ptr<insight::cad::Scalar>, boost::shared_ptr<insight::cad::Scalar> >&)’ is ambiguous

swap(a, b);

/usr/include/boost/core/swap.hpp:54:8: note: candidate: void boost::swap(T1&, T2&) [with T1 = boost::fusion::vector3<boost::shared_ptr<insight::cad::Scalar>, boost::shared_ptr<insight::cad::Scalar>, boost::shared_ptr<insight::cad::Scalar> >; T2 = boost::fusion::vector3<boost::shared_ptr<insight::cad::Scalar>, boost::shared_ptr<insight::cad::Scalar>, boost::shared_ptr<insight::cad::Scalar> >]

void swap(T1& left, T2& right)

/usr/include/boost/fusion/sequence/intrinsic/swap.hpp:57:5: note: candidate: typename boost::fusion::result_of::swap<Seq1, Seq2>::type boost::fusion::swap(Seq1&, Seq2&) [with Seq1 = boost::fusion::vector3<boost::shared_ptr<insight::cad::Scalar>, boost::shared_ptr<insight::cad::Scalar>, boost::shared_ptr<insight::cad::Scalar> >; Seq2 = boost::fusion::vector3<boost::shared_ptr<insight::cad::Scalar>, boost::shared_ptr<insight::cad::Scalar>, boost::shared_ptr<insight::cad::Scalar> >; typename boost::fusion::result_of::swap<Seq1, Seq2>::type = void]

swap(Seq1& lhs, Seq2& rhs)

[hannes@…]

Since there is no reaction, I suppose that my given information is a little sparse?

I investigated a bit:

The definition of "boost::fusion::swap" arises due to the inclusion of "/usr/include/boost/spirit/include/qi.hpp"

The definition of "boost::swap" comes via "/usr/include/boost/assign/list_of.hpp" Unfortunately, I need the "list_of" header in many places.

I have removed all "using namespace" statements. Unfortunately without success.

[hannes@…]

Minimum example

[hannes@…]

I managed to reduce my code into a demonstration minimum. You can find it in the attached file "test.cpp".

Compiling it on Ubuntu Xenial via

$ g++ test.cpp

fails with the described error.

[Joel de Guzman]

I confirmed this and I can repro on Clang.

[Joel de Guzman]

One plausible solution here is to use boost::swap and have fusion provide an overload for it.

[hannes@…]

I could compile the minimum example after inserting

namespace boost {
namespace fusion {
 void swap(MyList&a1, MyList&a2)
 {
  boost:swap(a1, a2);
 }
}
}

[Joel de Guzman]

fixed in boost-1.65 (not a spirit bug)