使用-O2on Clang 3.9 编译以下示例会导致reproFunction 1.9038e+185在调用时返回garbage()main:
double reproFunction(const Eigen::Matrix3d& R_in)
{
const Eigen::Matrix3d R = R_in;
Eigen::Matrix3d Q = R.cwiseAbs();
if(R(1,2) < 2) {
Eigen::Vector3d n{0, 1, R(1, 2)};
double s2 = R(1,2);
s2 /= n.norm();
}
return R(1, 2);
}
int main() {
Eigen::Matrix3d R;
R = Eigen::Matrix3d::Zero(3,3);
// This fails - reproFunction(R) returns 0
R(1, 2) = 0.7;
double R12 = reproFunction(R);
bool are_they_equal = (R12 == R(1,2));
std::cout << "R12 == R(1,2): …Run Code Online (Sandbox Code Playgroud)