Correct. The implementation I had in mind when I said "internal iterator"--and which I think I've coded before back almost two decades ago--is that the tuple one-by-one in-order does a placement new on each of its elements, calling a templated callback you provide which returns the element (so you get RVO through to the placement new); in the case of an exception, it knows which it has already done by code (not by state) and so can deconstruct the appropriate objects.