I think that would fix the issue at the type level (up to a point; for unsigned types, the "correct" type for the result of a subtraction is underdetermined --

I think that would fix the issue at the type level (up to a point; for unsigned types, the "correct" type for the result of a subtraction is underdetermined -- it could be any of {same type, larger signed type, same-size signed type} depending on the circumstances). But I think the more serious niggle is the fact that that first element shows up in the output at all. OTOH, I suppose you could write a discard_first iterator adaptor that ignores the first write and increment and passes the rest through to the underlying output iterator.