Hello Swift Community,
The review of SE-0052: "Change IteratorType post-nil guarantee" ran from April 28...May 3, 2016. The proposal is *accepted* for Swift 3.
The feedback on this proposal was generally positive from the community and core team. The most significant concern was about performance: strengthening the requirement on IteratorType.next() could make some implementations of iterators slower. On the other hand, it does make some clients faster (UTF8 decoding being one cited case that demonstrates a big win). The core team believes that the improvements to performance in the most common use-cases will more than balance the reductions in performance for other cases.
Thank you to Patrick Pijnappel for proposing and implementing this!