In general noone would write a function that took an int by const reference because doing so doesn't make sense from a performance standpoint. However often times we pass these trivial types to functions generically written to take const T&. It seems like type traits would make it simple to overload based on this convention. However I don't see a type trait that is fit for this use case. The has_trivial_copy trait would seem promising but it could return true for large pod objects that you wouldn't want to copy. The is_scalar trait seems promising but it will return false for lightweight user defined types and be suboptimal. Using has_trivial_copy together with some sizeof limit seems promising but a bit hand wavy. Is there a trait designed for this use case I'm overlooking? Thanks, Michael Marcin