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allocate(0) return?Section: 16.4.4.6[allocator.requirements]Status:TC1Submitter: Matt AusternOpened: 1999-11-19Last modified: 2016-01-28
Priority:Not Prioritized
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Discussion:
Suppose thatA is a class that conforms to theAllocator requirements of Table 32, anda is anobject of classA What should be the returnvalue ofa.allocate(0)? Three reasonablepossibilities: forbid the argument0, returna null pointer, or require that the return value be aunique non-null pointer.
Proposed resolution:
Add a note to theallocate row of Table 32:"[Note: Ifn == 0, the return value is unspecified.--end note]"
Rationale:
A key to understanding this issue is that the ultimate use ofallocate() is to construct an iterator, and that iterator for zerolength sequences must be the container's past-the-endrepresentation. Since this already implies special case code, itwould be over-specification to mandate the return value.