Hi Wei, As I understand it, yes, this is a known bug. The fix is to do something like this: #include <algorithm> ... bool x = (0, std::less<int>()(10, 20)); I'm willing to be the GNUrus are working diligently as I write this to address this issue and squelch this bug. Coming to a GCC compiler near you, real soon. Sincerely, --Eljay