check_cxx_source_compiles("
    #include <sys/types.h>
    #include <type_traits>
    int main() {
        static_assert(sizeof(off_t) == 8, \"\");
        return 0;
    }
" HAVE_LARGE_FILE_SUPPORT)

add_definitions(-DHAVE_LARGE_FILE_SUPPORT)

CHECK_C_SOURCE_RUNS("
#include <sys/types.h>
#define BIG_OFF_T (((off_t)1<<62)-1+((off_t)1<<62))
int main (int argc, char **argv) {
    int big_off_t=((BIG_OFF_T%2147483629==721) &&
                   (BIG_OFF_T%2147483647==1));
    return big_off ? 0 : 1;
}
" HAVE_LARGE_FILE_SUPPORT)