Proposed resolution:

This wording is relative to N4741.

1. Edit [span.overview] as indicated:

   -4- The iterator types for span is a random access iterator and a contiguous iteratorspan::iterator and span::const_iterator are random access iterators ([random.access.iterators]), contiguous iterators ([iterator.requirements.general]), and constexpr iterators ([iterator.requirements.general]). All requirements on container iterators ([container.requirements]) apply to span::iterator and span::const_iterator as well.

[ 2018-06 Rapperswil: Adopted ]

[ 2018-04-23 Moved to Tentatively Ready after 6 positive votes on c++std-lib. ]

There are multiple issues with how span specifies its iterators:

• const_iterator isn't mentioned.

• The relationship between iterator and const_iterator isn't specified. (span isn't a container, so it doesn't receive this automatically.)

• The iterators should be specified to be constexpr.

By imitating [string.view.iterators]/3 "All requirements on container iterators ([container.requirements]) apply to basic_string_view::const_iterator as well.", we can specify that iterator is convertible to const_iterator.