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### 589. Requirements on iterators of member template functions of containers

Section: 24.2 [container.requirements] Status: CD1 Submitter: Peter Dimov Opened: 2006-08-02 Last modified: 2016-01-28

Priority: Not Prioritized

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Duplicate of: 536

Discussion:

There appears to be no requirements on the InputIterators used in sequences in 23.1.1 in terms of their value_type, and the requirements in 23.1.2 appear to be overly strict (requires InputIterator::value_type be the same type as the container's value_type).

Proposed resolution:

Change 23.1.1 p3:

> In Tables 82 and 83, `X` denotes a sequence class, `a` denotes a value of `X`, `i` and `j` denote iterators satisfying input iterator requirements and refer to elements implicitly convertible to `value_type`, `[i, j)` denotes a valid range, `n` denotes a value of `X::size_type`, `p` denotes a valid iterator to `a`, `q` denotes a valid dereferenceable iterator to `a`, `[q1, q2)` denotes a valid range in `a`, and `t` denotes a value of `X::value_type`.

Change 23.1.2 p7:

> In Table 84, `X` is an associative container class, `a` is a value of `X`, `a_uniq` is a value of `X` when `X` supports unique keys, and `a_eq` is a value of `X` when `X` supports multiple keys, `i` and `j` satisfy input iterator requirements and refer to elements of implicitly convertible to `value_type`, `[i, j)` is a valid range, `p` is a valid iterator to `a`, `q` is a valid dereferenceable iterator to `a`, `[q1, q2)` is a valid range in `a`, `t` is a value of `X::value_type`, `k` is a value of `X::key_type` and `c` is a value of type `X::key_compare`.

Rationale:

Concepts will probably come in and rewrite this section anyway. But just in case it is easy to fix this up as a safety net and as a clear statement of intent.