Annex D (informative) Compatibility [diff]

D.2 Ranges and the Palo Alto TR (N3351) [diff.n3351]

D.2.3 No Distinct DistanceType Associated Type [diff.n3351.distance_type]

In the Palo Alto report, the WeaklyIncrementable concept has an associated type called DistanceType, and the RandomAccessIterator concepts adds another associated type called DifferenceType. The latter is required to be convertible to the former, but they are not required to be the same type. (DifferenceType is required to be a signed integral type, but DistanceType need not be signed.) Although sensible from a soundness point of view, the author of this document feels this is potentially a rich source of confusion. This document hews closer to the current standard by having only one associated type, DifferenceType, and requiring it to be signed.