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

**Section:** 21.2 [container.requirements] **Status:** CD1
**Submitter:** Peter Dimov **Opened:** 2006-08-02 **Last modified:** 2017-02-03

**Priority: **Not Prioritized

**View all other** issues in [container.requirements].

**View all issues with** CD1 status.

**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.