Add polygons with boost::polygon does not compile?

May be this is a stupid question and only a simple issue, but I fail compiling a relative simple code. What I try to do is to add/concatenate two polygons using boost::polygon (some pseudocode showing the relevant parts):

#include <boost/polygon/polygon.hpp>

boost::polygon::polygon_with_holes_data<int>     baseData; // base data to work with
boost::polygon::polygon_with_holes_data<int>     opData;   // operational data to be applied to base 

fill both baseData and opData via set() and set_holes() here...

boost::polygon::polygon_set_data<int> result=baseData + opData;

The last line is where I stumble upon: the compiler says the operator "+" is not known for polygon_with_holes_data:

error C2678: binary '+' : no operator found which takes a left-hand operand of type 'boost::polygon::polygon_with_holes_data<T>' (or there is no acceptable conversion)

When I use polygon_data instead of polygon_with_holes_data the same error appears. Any idea what I'm doing wrong?

Thanks!

The only operators I see mentioned in the documentation are on polygon sets

Also, note:

Operators are declared inside the namespace boost::polygon::operators.

So, making sure to actually use them:

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#include <boost/polygon/polygon.hpp>
#include <boost/polygon/polygon_set_data.hpp>
#include <boost/polygon/polygon_with_holes_data.hpp>

namespace bp = boost::polygon;
using poly = bp::polygon_with_holes_data<int>;
using pset = bp::polygon_set_data<int>;

int main() {
    poly baseData; // base data to work with
    poly opData;   // operational data to be applied to base

    // fill both baseData and opData via set() and set_holes() here...

    using namespace bp::operators;
    pset x = baseData + opData;
}