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### 2794. Missing requirements for allocator pointers

Section: 24.2.2.1 [container.requirements.general] Status: C++17 Submitter: Billy O'Neal III Opened: 2016-11-09 Last modified: 2017-07-30

Priority: 0

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Discussion:

Addresses US 146

An allocator-aware contiguous container must require an allocator whose pointer type is a contiguous iterator. Otherwise, functions like data for `basic_string` and `vector` do not work correctly, along with many other expectations of the contiguous guarantee.

Suggested resolution:

Add a second sentence to 24.2.2.1 [container.requirements.general] p13:

> An allocator-aware contiguous container requires `allocator_traits<Allocator>::pointer` is a contiguous iterator.

[2016-11-12, Issaquah]

Sat PM: Move to 'Tentatively Ready'

Proposed resolution:

This wording is relative to N4606.

1. In 16.4.4.6 [allocator.requirements]/5, edit as follows:

   > -5- An allocator type `X` shall satisfy the requirements of `CopyConstructible` (17.6.3.1). The `X::pointer`, `X::const_pointer`, `X::void_pointer`, and `X::const_void_pointer` types shall satisfy the requirements of `NullablePointer` (17.6.3.3). No constructor, comparison operator, copy operation, move operation, or swap operation on these pointer types shall exit via an exception. `X::pointer` and `X::const_pointer` shall also satisfy the requirements for a random access iterator (25.3 [iterator.requirements]25.3.5.7 [random.access.iterators]) and of a contiguous iterator (25.3.1 [iterator.requirements.general]).