Proposed resolution:

This wording is relative to N4958.

1. Modify [const.iterators.iterator], class template basic_const_iterator synopsis, as indicated:

   namespace std {
     […]
   
     template<input_iterator Iterator>
     class basic_const_iterator {
       […]
       constexpr const Iterator& base() const & noexcept;
       constexpr Iterator base() &&;
       […]
     };
   }
   

2. Modify [const.iterators.ops] as indicated:

   constexpr const Iterator& base() const & noexcept;
   

   -4- Effects: Equivalent to: return current_;

   constexpr Iterator base() &&;
   

   -5- Effects: Equivalent to: return std::move(current_);

3. Modify [range.as.const.view] as indicated:

   namespace std::ranges {
     template<view V>
       requires input_range<V>
     class as_const_view : public view_interface<as_const_view<V>> {
       […]
       constexpr V base() const & requires copy_constructible<V> { return base_; }
       constexpr V base() && { return std::move(base_); }
       […]
     };
   }