Using `tf::twistKDLToEigen` leads to compilation errors

[karthikeyaparunandi]

tf::twistKDLToEigen has a signature void twistKDLToEigen(const KDL::Twist &k, Eigen::Matrix<double, 6, 1> &e).

So, I have two variables that I passed into this function in my code: one the input (twist) and the other one the output (eigen_matrix) that is passed by reference as follows:

// I already have the object `twist` of type `KDL::Twist` with some value assigned to it
Eigen::Matrix<double, 6, 1> eigen_matrix;
tf::twistKDLToEigen(twist, eigen_matrix);

I'm seeing the following error at this place during compilation:

error: cannot bind non-const lvalue reference of type ‘Eigen::Matrix<double, 6, 1>&’ to an rvalue of type ‘Eigen::Matrix<double, 6, 1>’
     tf::twistKDLToEigen(twist, eigen_matrix)
                                                   ^
/usr/include/eigen3/Eigen/src/Core/Matrix.h:378:25: note:   after user-defined conversion: Eigen::Matrix<_Scalar, _Rows, _Cols, _Options, _MaxRows, _MaxCols>::Matrix(const Eigen::EigenBase<OtherDerived>&) [with OtherDerived = Eigen::Matrix<double, 1, 6>; _Scalar = double; int _Rows = 6; int _Cols = 1; int _Options = 0; int _MaxRows = 6; int _MaxCols = 1]
     EIGEN_STRONG_INLINE Matrix(const EigenBase<OtherDerived> &other)
                         ^~~~~~

In order to narrow down the issue, I wrote a test function with just the Eigen::Matrix<double, 6, 1> &e as an argument and saw the same error:

void test_twistKDLToEigen(Eigen::Matrix<double, 6, 1> &e){
     // do nothing
    return;
}

int main(){
Eigen::Matrix<double, 6, 1> test_eigen_matrix;
test_twistKDLToEigen(test_eigen_matrix);
}

Apparently, this error disappears as soon as the argument is Eigen::Matrix<double, 6, 1> e i.e, pass by value or const Eigen::Matrix<double, 6, 1> &e. Is there something I'm missing or is it a bug?