Yeah, I think this is probably sufficient without whole-program optimization, but I'm not sure it is with LTO. It might be sufficient today, but I can imagine Clang optimizing it away eventually. Really, the only realistic-yet-futureproof method I can imagine (and I'm not sure if it's even within the jurisdiction of the language spec) is either (a) exporting the variable, or (b) exposing its address through some other established I/O mechanism (like printf).