Proposed resolution:

This wording is relative to N4606.

1. Modify [string.io] as indicated:

   template<class charT, class traits, class Allocator>
     basic_ostream<charT, traits>&
       operator<<(basic_ostream<charT, traits>& os,
                  const basic_string<charT, traits, Allocator>& str);
   

   -5- Effects: Equivalent to: return os << basic_string_view<charT, traits>(str);Behaves as a formatted output function ([ostream.formatted.reqmts]) of os. Forms a character sequence seq, initially consisting of the elements defined by the range [str.begin(), str.end()). Determines padding for seq as described in [ostream.formatted.reqmts]. Then inserts seq as if by calling os.rdbuf()->sputn(seq, n), where n is the larger of os.width() and str.size(); then calls os.width(0).

   -6- Returns: os

2. Modify [string.view.io] as indicated:

   template<class charT, class traits>
     basic_ostream<charT, traits>&
       operator<<(basic_ostream<charT, traits>& os,
                  basic_string_view<charT, traits> str);
   

   -1- Effects: Equivalent to: return os << str.to_string();Behaves as a formatted output function ([ostream.formatted.reqmts]) of os. Forms a character sequence seq, initially consisting of the elements defined by the range [str.begin(), str.end()). Determines padding for seq as described in [ostream.formatted.reqmts]. Then inserts seq as if by calling os.rdbuf()->sputn(seq, n), where n is the larger of os.width() and str.size(); then calls os.width(0).

   -?- Returns: os

[ 2016-07 Chicago LWG ]

Monday: P0 - tentatively ready

[ 2016-07-26, Marshall suggests concrete wording ]

In looking at N4606, [string.view.io] has an Effects clause that references basic_string_view::to_string which no longer exists after the application of P0254R2.