#include "../Eigen/Sparse" #ifdef EIGEN_SHOULD_FAIL_TO_BUILD #define CV_QUALIFIER const #else #define CV_QUALIFIER #endif using namespace Eigen; void call_ref(Ref<SparseMatrix<float> > a) { } int main() { SparseMatrix<float> a(10,10); CV_QUALIFIER SparseMatrix<float>& ac(a); call_ref(ac); }