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### 3558. `elements_view::sentinel`'s first `operator-` has wrong return type

Section: 24.7.18.4 [range.elements.sentinel] Status: NAD Editorial Submitter: Hewill Kang Opened: 2021-05-28 Last modified: 2021-06-07

Priority: Not Prioritized

View all issues with NAD Editorial status.

Discussion:

Because the iterator type of the first `operator-` is `const iterator<OtherConst>&`, its return type should be `range_difference_t<maybe-const<OtherConst, V>>`.

[2021-06-07 Fixed by editorial issue #4603. Status changed: New → NAD Editorial.]

Proposed resolution:

This wording is relative to N4885.

1. Modify 24.7.18.4 [range.elements.sentinel] as indicated:

   > >         […]
   > >         template<bool OtherConst>
   > >           requires sized_sentinel_for<sentinel_t<Base>, iterator_t<maybe-const<OtherConst, V>>>
   > >         friend constexpr range_difference_t<Basemaybe-const<OtherConst, V>>
   > >           operator-(const iterator<OtherConst>& x, const sentinel& y);

   > >         template<bool OtherConst>
   > >           requires sized_sentinel_for<sentinel_t<Base>, iterator_t<maybe-const<OtherConst, V>>>
   > >         friend constexpr range_difference_t<maybe-const<OtherConst, V>>
   > >           operator-(const sentinel& x, const iterator<OtherConst>& y);
   > >       };
   > >     }

   > […]

   >     template<bool OtherConst>
   >       requires sized_sentinel_for<sentinel_t<Base>, iterator_t<maybe-const<OtherConst, V>>>
   >     friend constexpr range_difference_t<Basemaybe-const<OtherConst, V>>
   >       operator-(const iterator<OtherConst>& x, const sentinel& y);

   > > -5- Effects: Equivalent to: `return x.current_ - y.end_;`