C++程序  |  16行  |  240 B

#include "../Eigen/Core"

#ifdef EIGEN_SHOULD_FAIL_TO_BUILD
#define CV_QUALIFIER const
#else
#define CV_QUALIFIER
#endif

using namespace Eigen;

void foo(CV_QUALIFIER Matrix3d &m){
    Block<Matrix3d> b(m.block(0,0,3,3));
}

int main() {}