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### 3397. `ranges::basic_istream_view::iterator` should not provide `iterator_category`

Section: 26.6.6.3 [range.istream.iterator] Status: C++20 Submitter: Tomasz Kamiński Opened: 2020-02-13 Last modified: 2021-02-25

Priority: 1

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Discussion:

The `ranges::basic_istream_view::iterator` is a move-only type, and as such it does not meets the Cpp17 iterator requirements, yet it does provides `iterator_category` (intended to be used for Cpp17 iterators). We should provide `iterator_concept` instead.

[2020-02 Status to Immediate on Thursday night in Prague.]

Proposed resolution:

This wording is relative to N4849.

1. Modify 26.6.6.3 [range.istream.iterator] as indicated:

   >     namespace std::ranges {
   >       template<class Val, class CharT, class Traits>
   >       class basic_istream_view<Val, CharT, Traits>::iterator { // exposition only
   >       public:
   >         using iterator_categoryiterator_concept = input_iterator_tag;
   >         using difference_type = ptrdiff_t;
   >         using value_type = Val;

   >         iterator() = default;
   >         […]
   >       };
   >     }