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### 3364. Initialize data members of ranges and their iterators

Section: 26.7.11.2 [range.take.while.view], 26.7.12.2 [range.drop.view], 26.7.13.2 [range.drop.while.view], 26.7.22.3 [range.elements.iterator] Status: C++20 Submitter: Johel Ernesto Guerrero Peña Opened: 2020-01-07 Last modified: 2021-02-25

Priority: 0

View all other issues in [range.take.while.view].

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Discussion:

Before P1035 was accepted, no data member in [ranges] whose type could potentially be an aggregate or fundamental type was left without initializer. P1035 left some such data members without initializer, so it is possible to have them have indeterminate values. We propose restoring consistency.

[2020-01-14 Status set to Tentatively Ready after five positive votes on the reflector.]

Proposed resolution:

This wording is relative to N4842.

1. Modify 26.7.11.2 [range.take.while.view] as follows:

   >     class take_while_view : public view_interface<take_while_view<V, Pred>> {
   >       template<bool> class sentinel;                      // exposition only

   >       V base_ = V();                                      // exposition only
   >       semiregular-box<Pred> pred_;                        // exposition only

   >     public:

2. Modify 26.7.12.2 [range.drop.view] as follows:

   >     private:
   >       V base_ = V();                                     // exposition only
   >       range_difference_t<V> count_ = 0;                  // exposition only
   >     };

3. Modify 26.7.13.2 [range.drop.while.view] as follows:

   >     private:
   >       V base_ = V();                                     // exposition only
   >       semiregular-box<Pred> pred_;                       // exposition only
   >     };

4. Modify 26.7.22.3 [range.elements.iterator] as follows:

   >     class elements_view<V, N>::iterator {                // exposition only
   >       using base-t = conditional_t<Const, const V, V>;
   >       friend iterator<!Const>;

   >       iterator_t<base-t> current_ = iterator_t<base-t>();
   >     public: