1 #include "../Eigen/Core" 2 3 using namespace Eigen; 4 main()5 int main() 6 { 7 VectorXf a(10), b(10); 8 VectorXf const &ac(a); 9 #ifdef EIGEN_SHOULD_FAIL_TO_BUILD 10 b.swap(ac); 11 #else 12 b.swap(ac.const_cast_derived()); 13 #endif 14 }