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2794. Missing requirements for allocator pointers

Section: 21.2.1 [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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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 21.2.1 [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 [allocator.requirements]/5, edit as follows:

    -5- An allocator type X shall satisfy the requirements of CopyConstructible ( The X::pointer, X::const_pointer, X::void_pointer, and X::const_void_pointer types shall satisfy the requirements of NullablePointer ( 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 (22.2 [iterator.requirements]22.2.7 [random.access.iterators]) and of a contiguous iterator (22.2.1 [iterator.requirements.general]).