-fwhole-program is a compile-time optimization, not link-time. You shouldn't link anything to a translation unit compiled with -fwhole-program, as the whole poi

-fwhole-program is a compile-time optimization, not link-time. You shouldn't link anything to a translation unit compiled with -fwhole-program, as the whole point of it is to compile the whole application in a single translation unit and tell the compiler to optimize accordingly. It can also eliminate unused data and functions, as it basically treats most entites as internal linkage, and that's one of the optimisations applied there. The mechanism is rather different to GCing sections at link time though. I assume LTO has something similar. It's useful to combine it with unity builds. It's poor man's LTO in a way.