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1012.reverse_iterator default ctor should value initialize

Section: 24.5.1.4[reverse.iter.cons]Status:C++11Submitter: Alisdair MeredithOpened: 2009-03-11Last modified: 2016-01-28

Priority:Not Prioritized

View all otherissues in [reverse.iter.cons].

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Discussion:

Addresses UK 277

The default constructor default-initializes current, rather thanvalue-initializes. This means that when Iterator corresponds to atrivial type, the current member is left un-initialized, even when theuser explictly requests value intialization! At this point, it is notsafe to perform any operations on the reverse_iterator other than assignit a new value or destroy it. Note that this does correspond to thebasic definition of a singular iterator.

[Summit:]

Agree with option i.

Related issue:408⁽ⁱ⁾

[Batavia (2009-05):]

We believe this should be revisitedin conjunction with issue408⁽ⁱ⁾,which nearly duplicates this issue.Move to Open.

[2009-07 post-Frankfurt:]

Change "constructed" to "initialized" in two places in the proposed resolution.

Move to Tentatively Ready.

[2009 Santa Cruz:]

Moved to Ready for this meeting.

Proposed resolution:

Change [reverse.iter.con]:

reverse_iterator();

-1-Effects:DefaultValue initializescurrent. Iteratoroperations applied to the resulting iterator have defined behavior if andonly if the corresponding operations are defined on adefault constructedvalue initializediterator of typeIterator.

Change [move.iter.op.const]:

move_iterator();

-1-Effects: Constructs amove_iterator,defaultvalueinitializingcurrent.Iteratoroperations applied to the resulting iterator have defined behavior if andonly if the corresponding operations are defined on avalue initializediterator of typeIterator.