Proposed resolution:

This wording is relative to N4892.

1. Modify [range.iota.iterator] as indicated:

   friend constexpr iterator operator+(iterator i, difference_type n)
     requires advanceable<W>;
   

   -20- Effects: Equivalent to:

   return i += n; 
   return i;
   

   friend constexpr iterator operator+(difference_type n, iterator i)
     requires advanceable<W>;
   

   -21- Effects: Equivalent to: return i + n;

   friend constexpr iterator operator-(iterator i, difference_type n)
     requires advanceable<W>;
   

   -22- Effects: Equivalent to:

   return i -= n;
   return i;
   

[ 2021-10-14 Approved at October 2021 virtual plenary. Status changed: Voting → WP. ]

[ 2021-08-20; Reflector poll ]

Set status to Tentatively Ready after six votes in favour during reflector poll.

iota_view's iterator's operator+ could avoid a copy construct by doing "i += n; return i" rather than "return i += n;" as seen in [range.iota.iterator].

This is what libc++ has implemented and shipped, even though it may not technically be conforming (if a program asserted the number of copies, for example).

It might be good to update this operator and the minus operator accordingly.