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Section: 16.4.4.6 [allocator.requirements] Status: C++14 Submitter: Jonathan Wakely Opened: 2011-08-30 Last modified: 2016-01-28
Priority: Not Prioritized
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Discussion:
As discussed in c++std-lib-31054 and c++std-lib-31059, the Allocator requirements implicitly require CopyConstructible because a.select_on_container_copy_construction() and container.get_allocator() both return a copy by value, but the requirement is not stated explicitly anywhere.
In order to clarify that allocators cannot have 'explicit' copy constructors, the requirements should include CopyConstructible.[2012, Kona]
Move to Ready.
[2012, Portland: applied to WP]
Proposed resolution:
This wording is relative to the FDIS.
Change Table 28 — Allocator requirements in 16.4.4.6 [allocator.requirements]:
Expression | Return type | Assertion/note pre-/post-condition | Default |
---|---|---|---|
X a1(a); X a1 = a; |
Shall not exit via an exception. post: a1 == a |
||
… | |||
X a1(move(a)); X a1 = move(a); |
Shall not exit via an exception. post: a1 equals the prior value of a. |
Change 16.4.4.6 [allocator.requirements] paragraph 4:
An allocator type X shall satisfy the requirements of CopyConstructible (16.4.4.2 [utility.arg.requirements]). The X::pointer, X::const_pointer, X::void_pointer, and X::const_void_pointer types shall satisfy the requirements of NullablePointer (16.4.4.4 [nullablepointer.requirements]). No constructor, comparison operator, copy operation, move operation, or swap operation on these 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]).