https://gcc.gnu.org/bugzilla/show_bug.cgi?id=83279
--- Comment #4 from Jonathan Wakely <redi at gcc dot gnu.org> --- What does this output, for both gcc-5 and gcc-7? #include <iostream> int main() { std::cout << "Large file support: " #ifdef _GLIBCXX_USE_LFS "enabled" #else "disabled" #endif "\n"; }