allocator::addressSection: 16.4.4.6 [allocator.requirements] Status: Resolved Submitter: Howard Hinnant Opened: 2007-02-08 Last modified: 2016-01-28
Priority: Not Prioritized
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Discussion:
The table of allocator requirements in 16.4.4.6 [allocator.requirements] describes
allocator::address as:
a.address(r) a.address(s)
where r and s are described as:
a value of type
X::referenceobtained by the expression*p.
and p is
a value of type
X::pointer, obtained by callinga1.allocate, wherea1 == a
This all implies that to get the address of some value of type T that
value must have been allocated by this allocator or a copy of it.
However sometimes container code needs to compare the address of an external value of
type T with an internal value. For example list::remove(const T& t)
may want to compare the address of the external value t with that of a value
stored within the list. Similarly vector or deque insert may
want to make similar comparisons (to check for self-referencing calls).
Mandating that allocator::address can only be called for values which the
allocator allocated seems overly restrictive.
[ post San Francisco: ]
Pablo recommends NAD Editorial, solved by N2768.
[ 2009-04-28 Pablo adds: ]
Tentatively-ready NAD Editorial as fixed by N2768.
[ 2009-07 Frankfurt ]
Fixed by N2768.
[ 2009-07-28 Reopened by Alisdair. No longer solved by concepts. ]
[ 2009-10 Santa Cruz: ]
NAD EditorialResolved. Addressed by N2982.
Proposed resolution:
Change 16.4.4.6 [allocator.requirements]:
r: a value of typeX::referenceobtained by the expression *p.
s: a value of typeX::const_referenceobtained by the expression.*qor by conversion from a valuer
[ post Oxford: This would be rendered NAD Editorial by acceptance of N2257. ]
[ Kona (2007): This issue is section 8 of N2387. There was some discussion of it but no resolution to this issue was recorded. Moved to Open. ]