https://gcc.gnu.org/bugzilla/show_bug.cgi?id=64814
--- Comment #5 from Anquietas <alex-j-a at hotmail dot co.uk> --- (In reply to Jonathan Wakely from comment #3) > However, I don't see any requirement in the standard that says we're > supposed to do so. All that is required is n assignments, there is no > guarantee that the input range is also incremented past the last element > written to. The closest thing I could find to an up to date copy of the C++11 standard: http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2012/n3337.pdf copy_n is on page 851 "Effects: For each non-negative integer i < n, performs *(result + i) = *(first + i)." Since it's talking about input iterators where (first + n) isn't valid I think we can interpret this as n applications each of ++first and *first. I don't know whether the most recent version changed the description though; perhaps if you could provide a link?
