Hi Thomas,
Thank you very much for your experience and advice. Since that time, I have been using libtorch 1.9.0. And after searching some information on internet, I have found that if I add add_link_options(-fuse-ld=gold) in CMakeLists.txt, the warning message disappeared. So in my opinion , I guess the libtorch 1.9.0 was build with ld.gold linker for large project or application. Maybe I am wrong about that, but compiling code successfully without warning message makes me happy.
Best regards,
Fitanium