Issue 18219: Block decrement_count() is problematic in some cases (vsiplxx-rtf)
Source:  (Mr. Brooks Moses, brooks.moses(at)dpdx.net)
Nature: Revision
Severity: Minor
Summary: The effects of the decrement_count() accessor for blocks are described
as "Decrease the object’s use count. If the count becomes zero, the
block deallocates itself."


This is not always possible.  Consider, for instance, this simple code:


  Dense<...> block(...);
  block.decrement_count();


Since block is created on the stack, it cannot deallocate itself.


Similar issues will occur with blocks created using placement-new into
existing allocated memory.


At minimum, this should be addressed by a clause stating that the
object's use-count shall not be decremented to zero (or allowed to
become decremented to zero) except for blocks that have been created
using "new".


Resolution: In the interest of closing the current RTF so that the solutions to resolved issues can be made publically available, this issue is deferred to the next RTF.
Disposition: Deferred
Revised Text: 
Actions taken:
October 23, 2012: received issue
Discussion: 

End of Annotations:=====
te: Tue, 23 Oct 2012 13:33:13 -0700
From: Brooks Moses <brooks_moses@mentor.com>
User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:10.0.2) Gecko/20120216 Thunderbird/10.0.2
To: <issues@omg.org>
Subject: VSIPL++ issue (#22 from me)
X-OriginalArrivalTime: 23 Oct 2012 20:33:14.0387 (UTC) FILETIME=[A058EE30:01CDB15D]


Name:            Brooks Moses
Employer:        Mentor Graphics
mailFrom:        brooks_moses@mentor.com
Terms_Agreement: I agree
Specification:   VSIPL++
Section:         6.3.6 [block.dense.accessors]
FormalNumber:    ptc/2012-07-27
Version:         1.2 - FTF Beta 1
Doc_Year:        2012
Doc_Month:       August
Doc_Day:         10
Page:            39
Title:           Block decrement_count() is problematic in some cases
Nature:          Bug
Severity:        Minor
B1:              Report Issue


Description:


The effects of the decrement_count() accessor for blocks are described
as "Decrease the object.s use count. If the count becomes zero, the
block deallocates itself."


This is not always possible.  Consider, for instance, this simple code:


  Dense<...> block(...);
  block.decrement_count();


Since block is created on the stack, it cannot deallocate itself.


Similar issues will occur with blocks created using placement-new into
existing allocated memory.


At minimum, this should be addressed by a clause stating that the
object's use-count shall not be decremented to zero (or allowed to
become decremented to zero) except for blocks that have been created
using "new".

- Brooks