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2006-04-23  Paolo Carlini  <pcarlini@suse.de>

	* docs/html/ext/lwg-active.html, lwg-defects.html: Import Revision 42.

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libstdc++-v3/ChangeLog
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2006-04-23 Paolo Carlini <pcarlini@suse.de>
* docs/html/ext/lwg-active.html, lwg-defects.html: Import Revision 42.
2006-04-19 Paolo Carlini <pcarlini@suse.de>
PR libstdc++/26424

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@ -8,11 +8,11 @@ del {background-color:#FFFFA0}</style></head>
<table>
<tbody><tr>
<td align="left">Doc. no.</td>
<td align="left">N1950=06-0020</td>
<td align="left">N2001=06-0071</td>
</tr>
<tr>
<td align="left">Date:</td>
<td align="left">2006-02-24</td>
<td align="left">2006-04-21</td>
</tr>
<tr>
<td align="left">Project:</td>
@ -23,7 +23,7 @@ del {background-color:#FFFFA0}</style></head>
<td align="left">Howard Hinnant &lt;howard.hinnant@gmail.com&gt;</td>
</tr>
</tbody></table>
<h1>C++ Standard Library Defect Report List (Revision R41)</h1>
<h1>C++ Standard Library Defect Report List (Revision R42)</h1>
<p>Reference ISO/IEC IS 14882:1998(E)</p>
<p>Also see:</p>
<ul>
@ -45,6 +45,15 @@ del {background-color:#FFFFA0}</style></head>
document.</p>
<h2>Revision History</h2>
<ul>
<li>R42:
2006-04-21 post-Berlin mailing.
Added new issues <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#567">567</a>-<a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#572">572</a>.
Moved issues <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-closed.html#499">499</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-closed.html#501">501</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-closed.html#506">506</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-closed.html#509">509</a>-<a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-closed.html#511">511</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-closed.html#513">513</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-closed.html#514">514</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-closed.html#517">517</a> to NAD.
Moved issues <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#502">502</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#503">503</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#515">515</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#516">516</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#522">522</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#525">525</a>-<a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#529">529</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#532">532</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#536">536</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#539">539</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#548">548</a> to Open.
Moved issue <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#504">504</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#512">512</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#521">521</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#530">530</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#531">531</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#535">535</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#537">537</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#538">538</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#540">540</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#549">549</a> to Ready.
Moved issues <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#247">247</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#294">294</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#362">362</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#369">369</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#371">371</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#376">376</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#384">384</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#475">475</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#478">478</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#495">495</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#497">497</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#505">505</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#507">507</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#508">508</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#519">519</a> to WP.
Moved issue <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#534">534</a> to Review.
</li>
<li>R41:
2006-02-24 pre-Berlin mailing.
Added new issues <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#536">536</a>-<a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#566">566</a>.
@ -59,9 +68,9 @@ Added new issues <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active
2005-10-14 post-Mont Tremblant mailing.
Added new issues <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#526">526</a>-<a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#528">528</a>.
Moved issues <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#280">280</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#461">461</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#464">464</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#465">465</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#467">467</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#468">468</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#474">474</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#496">496</a> from Ready to WP as per the vote from Mont Tremblant.
Moved issues <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#247">247</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#294">294</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#342">342</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#362">362</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#369">369</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#371">371</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#376">376</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#384">384</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#475">475</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#478">478</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#495">495</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#497">497</a> from Review to Ready.
Moved issues <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#498">498</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#504">504</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#506">506</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#509">509</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#510">510</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#511">511</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#512">512</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#513">513</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#514">514</a> from New to Open.
Moved issues <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#505">505</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#507">507</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#508">508</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#519">519</a> from New to Ready.
Moved issues <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#247">247</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#294">294</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#342">342</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#362">362</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#369">369</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#371">371</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#376">376</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#384">384</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#475">475</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#478">478</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#495">495</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#497">497</a> from Review to Ready.
Moved issues <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#498">498</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#504">504</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-closed.html#506">506</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-closed.html#509">509</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-closed.html#510">510</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-closed.html#511">511</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#512">512</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-closed.html#513">513</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-closed.html#514">514</a> from New to Open.
Moved issues <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#505">505</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#507">507</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#508">508</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#519">519</a> from New to Ready.
Moved issue <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-closed.html#500">500</a> from New to NAD.
Moved issue <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#518">518</a> from New to Review.
</li>
@ -96,7 +105,7 @@ new issues <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#
<li>R31:
2004-07 mid-term mailing: reflects new proposed resolutions and
new issues received after the post-Sydney mailing. Added
new issues <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#463">463</a>-<a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#478">478</a>.
new issues <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#463">463</a>-<a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#478">478</a>.
</li>
<li>R30:
Post-Sydney mailing: reflects decisions made at the Sydney meeting.
@ -133,7 +142,7 @@ Pre-Santa Cruz mailing. Added new issues <a href="http://www.open-std.org/jtc1/
Moved issues in the TC to TC status.
</li>
<li>R22:
Post-Curaçao mailing. Added new issues <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#362">362</a>-<a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-closed.html#366">366</a>.
Post-Curaçao mailing. Added new issues <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#362">362</a>-<a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-closed.html#366">366</a>.
</li>
<li>R21:
Pre-Curaçao mailing. Added new issues <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-closed.html#351">351</a>-<a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-closed.html#361">361</a>.
@ -5367,7 +5376,7 @@ not required elsewhere.</p>
<p><i>[Kona: The LWG agreed there was a defect.]</i></p>
<p><i>[Tokyo: The LWG crafted the proposed resolution.]</i></p>
<hr>
<a name="186"><h3>186.&nbsp;bitset::set() second parameter should be bool</h3></a><p><b>Section:</b>&nbsp;23.3.5.2 <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lib-containers.html#lib.bitset.members"> [lib.bitset.members]</a>&nbsp; <b>Status:</b>&nbsp;<a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#WP">WP</a>&nbsp; <b>Submitter:</b>&nbsp;Darin Adler&nbsp; <b>Date:</b>&nbsp;13 Aug 1999</p>
<a name="186"></a><h3><a name="186">186.&nbsp;bitset::set() second parameter should be bool</a></h3><p><b>Section:</b>&nbsp;23.3.5.2 <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lib-containers.html#lib.bitset.members"> [lib.bitset.members]</a>&nbsp; <b>Status:</b>&nbsp;<a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#WP">WP</a>&nbsp; <b>Submitter:</b>&nbsp;Darin Adler&nbsp; <b>Date:</b>&nbsp;13 Aug 1999</p>
<p>In section 23.3.5.2 <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lib-containers.html#lib.bitset.members"> [lib.bitset.members]</a>, paragraph 13 defines the
bitset::set operation to take a second parameter of type int. The
function tests whether this value is non-zero to determine whether to
@ -7267,6 +7276,69 @@ had language that made this an unambiguous requirement; those words
were moved to a place where their context made them less clear. See
Jerry Schwarz's message c++std-lib-7618.</p>
<hr>
<a name="247"><h3>247.&nbsp;<tt>vector</tt>, <tt>deque::insert</tt> complexity</h3></a><p><b>Section:</b>&nbsp;23.2.4.3 <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lib-containers.html#lib.vector.modifiers"> [lib.vector.modifiers]</a>&nbsp; <b>Status:</b>&nbsp;<a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#WP">WP</a>&nbsp; <b>Submitter:</b>&nbsp;Lisa Lippincott&nbsp; <b>Date:</b>&nbsp;06 June 2000</p>
<p>Paragraph 2 of 23.2.4.3 [lib.vector.modifiers] describes the complexity
of <tt>vector::insert</tt>:</p>
<blockquote>
Complexity: If first and last are forward iterators, bidirectional
iterators, or random access iterators, the complexity is linear in
the number of elements in the range [first, last) plus the distance
to the end of the vector. If they are input iterators, the complexity
is proportional to the number of elements in the range [first, last)
times the distance to the end of the vector.
</blockquote>
<p>First, this fails to address the non-iterator forms of
<tt>insert</tt>.</p>
<p>Second, the complexity for input iterators misses an edge case --
it requires that an arbitrary number of elements can be added at
the end of a <tt>vector</tt> in constant time.</p>
<p>I looked to see if <tt>deque</tt> had a similar problem, and was
surprised to find that <tt>deque</tt> places no requirement on the
complexity of inserting multiple elements (23.2.1.3 <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lib-containers.html#lib.deque.modifiers"> [lib.deque.modifiers]</a>,
paragraph 3):</p>
<blockquote>
Complexity: In the worst case, inserting a single element into a
deque takes time linear in the minimum of the distance from the
insertion point to the beginning of the deque and the distance
from the insertion point to the end of the deque. Inserting a
single element either at the beginning or end of a deque always
takes constant time and causes a single call to the copy constructor
of T.
</blockquote>
<p><b>Proposed resolution:</b></p>
<p>Change Paragraph 2 of 23.2.4.3 [lib.vector.modifiers] to</p>
<blockquote>
Complexity: The complexity is linear in the number of elements
inserted plus the distance to the end of the vector.
</blockquote>
<p><i>[For input iterators, one may achieve this complexity by first
inserting at the end of the <tt>vector</tt>, and then using
<tt>rotate</tt>.]</i></p>
<p>Change 23.2.1.3 <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lib-containers.html#lib.deque.modifiers"> [lib.deque.modifiers]</a>, paragraph 3, to:</p>
<blockquote>
Complexity: The complexity is linear in the number of elements
inserted plus the shorter of the distances to the beginning and
end of the deque. Inserting a single element at either the
beginning or the end of a deque causes a single call to the copy
constructor of T.
</blockquote>
<p><b>Rationale:</b></p>
<p>This is a real defect, and proposed resolution fixes it: some
complexities aren't specified that should be. This proposed
resolution does constrain deque implementations (it rules out the
most naive possible implementations), but the LWG doesn't see a
reason to permit that implementation.</p>
<hr>
<a name="248"><h3>248.&nbsp;time_get fails to set eofbit</h3></a><p><b>Section:</b>&nbsp;22.2.5 <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lib-locales.html#lib.category.time"> [lib.category.time]</a>&nbsp; <b>Status:</b>&nbsp;<a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#WP">WP</a>&nbsp; <b>Submitter:</b>&nbsp;Martin Sebor&nbsp; <b>Date:</b>&nbsp;22 June 2000</p>
<p>There is no requirement that any of time_get member functions set
ios::eofbit when they reach the end iterator while parsing their input.
@ -8936,6 +9008,54 @@ the corresponding member objects of <tt>rhs</tt>, except that...
assigns to the member objects of <tt>*this</tt> the corresponding member
objects of <tt>rhs</tt>, except that...
</blockquote>
<hr>
<a name="294"><h3>294.&nbsp;User defined macros and standard headers</h3></a><p><b>Section:</b>&nbsp;17.4.3.1.1 <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lib-intro.html#lib.macro.names"> [lib.macro.names]</a>&nbsp; <b>Status:</b>&nbsp;<a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#WP">WP</a>&nbsp; <b>Submitter:</b>&nbsp;James Kanze&nbsp; <b>Date:</b>&nbsp;11 Jan 2001</p>
<p>Paragraph 2 of 17.4.3.1.1 <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lib-intro.html#lib.macro.names"> [lib.macro.names]</a> reads: "A
translation unit that includes a header shall not contain any macros
that define names declared in that header." As I read this, it
would mean that the following program is legal:</p>
<pre> #define npos 3.14
#include &lt;sstream&gt;
</pre>
<p>since npos is not defined in &lt;sstream&gt;. It is, however, defined
in &lt;string&gt;, and it is hard to imagine an implementation in
which &lt;sstream&gt; didn't include &lt;string&gt;.</p>
<p>I think that this phrase was probably formulated before it was
decided that a standard header may freely include other standard
headers. The phrase would be perfectly appropriate for C, for
example. In light of 17.4.4.1 <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lib-intro.html#lib.res.on.headers"> [lib.res.on.headers]</a> paragraph 1, however,
it isn't stringent enough.</p>
<p><b>Proposed resolution:</b></p>
<p>For 17.4.3.1.1 <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lib-intro.html#lib.macro.names"> [lib.macro.names]</a>, replace the current wording, which reads:</p>
<blockquote>
<p>Each name defined as a macro in a header is reserved to the
implementation for any use if the translation unit includes
the header.168)</p>
<p>A translation unit that includes a header shall not contain any
macros that define names declared or defined in that header. Nor shall
such a translation unit define macros for names lexically
identical to keywords.</p>
<p>168) It is not permissible to remove a library macro definition by
using the #undef directive.</p>
</blockquote>
<p>with the wording:</p>
<blockquote>
<p>A translation unit that includes a standard library header shall not
#define or #undef names declared in any standard library header.</p>
<p>A translation unit shall not #define or #undef names lexically
identical to keywords.</p>
</blockquote>
<p><i>[Lillehammer: Beman provided new wording]</i></p>
<hr>
<a name="295"><h3>295.&nbsp;Is abs defined in &lt;cmath&gt;?</h3></a><p><b>Section:</b>&nbsp;26.5 <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lib-numerics.html#lib.c.math"> [lib.c.math]</a>&nbsp; <b>Status:</b>&nbsp;<a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#WP">WP</a>&nbsp; <b>Submitter:</b>&nbsp;Jens Maurer&nbsp; <b>Date:</b>&nbsp;12 Jan 2001</p>
<p>
@ -11330,6 +11450,54 @@ prevents locale from being implemented efficiently.
<p>This change is reasonable becuase it clarifies the intent of this
part of the standard.</p>
<hr>
<a name="362"><h3>362.&nbsp;bind1st/bind2nd type safety</h3></a><p><b>Section:</b>&nbsp;20.3.6.2 <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lib-utilities.html#lib.bind.1st"> [lib.bind.1st]</a>&nbsp; <b>Status:</b>&nbsp;<a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#WP">WP</a>&nbsp; <b>Submitter:</b>&nbsp;Andrew Demkin&nbsp; <b>Date:</b>&nbsp;26 Apr 2002</p>
<p>
The definition of bind1st() (20.3.6.2 <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lib-utilities.html#lib.bind.1st"> [lib.bind.1st]</a>) can result in
the construction of an unsafe binding between incompatible pointer
types. For example, given a function whose first parameter type is
'pointer to T', it's possible without error to bind an argument of
type 'pointer to U' when U does not derive from T:
</p>
<pre> foo(T*, int);
struct T {};
struct U {};
U u;
int* p;
int* q;
for_each(p, q, bind1st(ptr_fun(foo), &amp;u)); // unsafe binding
</pre>
<p>
The definition of bind1st() includes a functional-style conversion to
map its argument to the expected argument type of the bound function
(see below):
</p>
<pre> typename Operation::first_argument_type(x)
</pre>
<p>
A functional-style conversion (5.2.3 <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/expr.html#expr.type.conv"> [expr.type.conv]</a>) is defined to be
semantically equivalent to an explicit cast expression (5.4 <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/expr.html#expr.cast"> [expr.cast]</a>), which may (according to 5.4, paragraph 5) be interpreted
as a reinterpret_cast, thus masking the error.
</p>
<p>The problem and proposed change also apply to 20.3.6.4 <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lib-utilities.html#lib.bind.2nd"> [lib.bind.2nd]</a>.</p>
<p><b>Proposed resolution:</b></p>
<p>Add this sentence to the end of 20.3.6 <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lib-utilities.html#lib.binders"> [lib.binders]</a>/1:
"Binders <tt>bind1st</tt> and <tt>bind2nd</tt> are deprecated in
favor of <tt>std::tr1::bind</tt>."</p>
<p>(Notes to editor: (1) when and if tr1::bind is incorporated into
the standard, "std::tr1::bind" should be changed to "std::bind". (2)
20.3.6 should probably be moved to Annex D.</p>
<p><b>Rationale:</b></p>
<p>There is no point in fixing bind1st and bind2nd. tr1::bind is a
superior solution. It solves this problem and others.</p>
<hr>
<a name="363"><h3>363.&nbsp;Missing exception specification in 27.4.2.1.1</h3></a><p><b>Section:</b>&nbsp;27.4.2.1.1 <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lib-iostreams.html#lib.ios::failure"> [lib.ios::failure]</a>&nbsp; <b>Status:</b>&nbsp;<a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#WP">WP</a>&nbsp; <b>Submitter:</b>&nbsp;Walter Brown and Marc Paterno&nbsp; <b>Date:</b>&nbsp;20 May 2002</p>
<p>
The destructor of ios_base::failure should have an empty throw
@ -11413,6 +11581,102 @@ state exposed by the public interface is unchanged.</p>
<p>Note that implementers can make this change in a binary compatible
way by providing both overloads; this would be a conforming extension.</p>
<hr>
<a name="369"><h3>369.&nbsp;io stream objects and static ctors</h3></a><p><b>Section:</b>&nbsp;27.3 <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lib-iostreams.html#lib.iostream.objects"> [lib.iostream.objects]</a>&nbsp; <b>Status:</b>&nbsp;<a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#WP">WP</a>&nbsp; <b>Submitter:</b>&nbsp;Ruslan Abdikeev&nbsp; <b>Date:</b>&nbsp;8 Jul 2002</p>
<p>
Is it safe to use standard iostream objects from constructors of
static objects? Are standard iostream objects constructed and are
their associations established at that time?
</p>
<p>Surpisingly enough, Standard does NOT require that.</p>
<p>
27.3/2 [lib.iostream.objects] guarantees that standard iostream
objects are constructed and their associations are established before
the body of main() begins execution. It also refers to ios_base::Init
class as the panacea for constructors of static objects.
</p>
<p>
However, there's nothing in 27.3 [lib.iostream.objects],
in 27.4.2 [lib.ios.base], and in 27.4.2.1.6 [lib.ios::Init],
that would require implementations to allow access to standard
iostream objects from constructors of static objects.
</p>
<p>Details:</p>
<p>Core text refers to some magic object ios_base::Init, which will
be discussed below:</p>
<blockquote>
"The [standard iostream] objects are constructed, and their
associations are established at some time prior to or during
first time an object of class basic_ios&lt;charT,traits&gt;::Init
is constructed, and in any case before the body of main
begins execution." (27.3/2 [lib.iostream.objects])
</blockquote>
<p>
The first <i>non-normative</i> footnote encourages implementations
to initialize standard iostream objects earlier than required.
</p>
<p>However, the second <i>non-normative</i> footnote makes an explicit
and unsupported claim:</p>
<blockquote>
"Constructors and destructors for static objects can access these
[standard iostream] objects to read input from stdin or write output
to stdout or stderr." (27.3/2 footnote 265 [lib.iostream.objects])
</blockquote>
<p>
The only bit of magic is related to that ios_base::Init class. AFAIK,
the rationale behind ios_base::Init was to bring an instance of this
class to each translation unit which #included &lt;iostream&gt; or
related header. Such an inclusion would support the claim of footnote
quoted above, because in order to use some standard iostream object it
is necessary to #include &lt;iostream&gt;.
</p>
<p>
However, while Standard explicitly describes ios_base::Init as
an appropriate class for doing the trick, I failed to found a
mention of an _instance_ of ios_base::Init in Standard.
</p>
<p><b>Proposed resolution:</b></p>
<p>Add to 27.3 <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lib-iostreams.html#lib.iostream.objects"> [lib.iostream.objects]</a>, p2, immediately before the last sentence
of the paragraph, the following two sentences:</p>
<blockquote>
If a translation unit includes &lt;iostream&gt;, or explicitly
constructs an ios_base::Init object, these stream objects shall
be constructed before dynamic initialization of non-local
objects defined later in that translation unit, and these stream
objects shall be destroyed after the destruction of dynamically
initialized non-local objects defined later in that translation unit.
</blockquote>
<p><i>[Lillehammer: Matt provided wording.]</i></p>
<p><i>[Mont Tremblant: Matt provided revised wording.]</i></p>
<p><b>Rationale:</b></p>
<p>
The original proposed resolution unconditionally required
implementations to define an ios_base::Init object of some
implementation-defined name in the header &lt;iostream&gt;. That's an
overspecification. First, defining the object may be unnecessary
and even detrimental to performance if an implementation can
guarantee that the 8 standard iostream objects will be initialized
before any other user-defined object in a program. Second, there
is no need to require implementations to document the name of the
object.</p>
<p>
The new proposed resolution gives users guidance on what they need to
do to ensure that stream objects are constructed during startup.</p>
<hr>
<a name="370"><h3>370.&nbsp;Minor error in basic_istream::get</h3></a><p><b>Section:</b>&nbsp;27.6.1.3 <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lib-iostreams.html#lib.istream.unformatted"> [lib.istream.unformatted]</a>&nbsp; <b>Status:</b>&nbsp;<a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#WP">WP</a>&nbsp; <b>Submitter:</b>&nbsp;Ray Lischner&nbsp; <b>Date:</b>&nbsp;15 Jul 2002</p>
<p>Defect report for description of basic_istream::get (section 27.6.1.3 <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lib-iostreams.html#lib.istream.unformatted"> [lib.istream.unformatted]</a>), paragraph 15. The description for the get function
@ -11444,6 +11708,82 @@ with the following signature:</p>
<p><b>Rationale:</b></p>
<p>Fixes an obvious typo.</p>
<hr>
<a name="371"><h3>371.&nbsp;Stability of multiset and multimap member functions</h3></a><p><b>Section:</b>&nbsp;23.1 <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lib-containers.html#lib.container.requirements"> [lib.container.requirements]</a>&nbsp; <b>Status:</b>&nbsp;<a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#WP">WP</a>&nbsp; <b>Submitter:</b>&nbsp;Frank Compagner&nbsp; <b>Date:</b>&nbsp;20 Jul 2002</p>
<p>
The requirements for multiset and multimap containers (23.1
[lib.containers.requirements], 23.1.2 [lib.associative.reqmnts],
23.3.2 [lib.multimap] and 23.3.4 [lib.multiset]) make no mention of
the stability of the required (mutating) member functions. It appears
the standard allows these functions to reorder equivalent elements of
the container at will, yet the pervasive red-black tree implementation
appears to provide stable behaviour.
</p>
<p>This is of most concern when considering the behaviour of erase().
A stability requirement would guarantee the correct working of the
following 'idiom' that removes elements based on a certain predicate
function.
</p>
<pre> multimap&lt;int, int&gt; m;
multimap&lt;int, int&gt;::iterator i = m.begin();
while (i != m.end()) {
if (pred(i))
m.erase (i++);
else
++i;
}
</pre>
<p>
Although clause 23.1.2/8 guarantees that i remains a valid iterator
througout this loop, absence of the stability requirement could
potentially result in elements being skipped. This would make
this code incorrect, and, furthermore, means that there is no way
of erasing these elements without iterating first over the entire
container, and second over the elements to be erased. This would
be unfortunate, and have a negative impact on both performance and
code simplicity.
</p>
<p>
If the stability requirement is intended, it should be made explicit
(probably through an extra paragraph in clause 23.1.2).
</p>
<p>
If it turns out stability cannot be guaranteed, i'd argue that a
remark or footnote is called for (also somewhere in clause 23.1.2) to
warn against relying on stable behaviour (as demonstrated by the code
above). If most implementations will display stable behaviour, any
problems emerging on an implementation without stable behaviour will
be hard to track down by users. This would also make the need for an
erase_if() member function that much greater.
</p>
<p>This issue is somewhat related to LWG issue <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#130">130</a>.</p>
<p><b>Proposed resolution:</b></p>
<p>Add the following to the end of 23.1.2 <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lib-containers.html#lib.associative.reqmts"> [lib.associative.reqmts]</a> paragraph 4:
"For <tt>multiset</tt> and <tt>multimap</tt>, <tt>insert</tt>and <tt>erase</tt>
are <i>stable</i>: they preserve the relative ordering of equivalent
elements.</p>
<p><i>[Lillehammer: Matt provided wording]</i></p>
<p><i>[Joe Gottman points out that the provided wording does not address
multimap and multiset. N1780 also addresses this issue and suggests
wording.]</i></p>
<p><i>[Mont Tremblant: Changed set and map to multiset and multimap.]</i></p>
<p><b>Rationale:</b></p>
<p>The LWG agrees that this guarantee is necessary for common user
idioms to work, and that all existing implementations provide this
property. Note that this resolution guarantees stability for
multimap and multiset, not for all associative containers in
general.</p>
<hr>
<a name="373"><h3>373.&nbsp;Are basic_istream and basic_ostream to use (exceptions()&amp;badbit) != 0 ?</h3></a><p><b>Section:</b>&nbsp;27.6.1.2.1 <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lib-iostreams.html#lib.istream.formatted.reqmts"> [lib.istream.formatted.reqmts]</a>, 27.6.2.5.1 <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lib-iostreams.html#lib.ostream.formatted.reqmts"> [lib.ostream.formatted.reqmts]</a>&nbsp; <b>Status:</b>&nbsp;<a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#WP">WP</a>&nbsp; <b>Submitter:</b>&nbsp;Keith Baker&nbsp; <b>Date:</b>&nbsp;23 Jul 2002</p>
@ -11476,6 +11816,42 @@ paragraph 14 to "ios_base".
<p><b>Rationale:</b></p>
<p>Fixes an obvious typo.</p>
<hr>
<a name="376"><h3>376.&nbsp;basic_streambuf semantics</h3></a><p><b>Section:</b>&nbsp;27.7.1.3 <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lib-iostreams.html#lib.stringbuf.virtuals"> [lib.stringbuf.virtuals]</a>&nbsp; <b>Status:</b>&nbsp;<a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#WP">WP</a>&nbsp; <b>Submitter:</b>&nbsp;Ray Lischner&nbsp; <b>Date:</b>&nbsp;14 Aug 2002</p>
<p>
In Section 27.7.1.3 <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lib-iostreams.html#lib.stringbuf.virtuals"> [lib.stringbuf.virtuals]</a>, Table 90, the implication is that
the four conditions should be mutually exclusive, but they are not.
The first two cases, as written, are subcases of the third.</p>
<p>
As written, it is unclear what should be the result if cases 1 and 2
are both true, but case 3 is false.
</p>
<p><b>Proposed resolution:</b></p>
<p>Rewrite these conditions as:</p>
<blockquote>
<p>
(which &amp; (ios_base::in|ios_base::out)) == ios_base::in
</p>
<p>
(which &amp; (ios_base::in|ios_base::out)) == ios_base::out
</p>
<p>
(which &amp; (ios_base::in|ios_base::out)) ==
(ios_base::in|ios_base::out)
and way == either ios_base::beg or ios_base::end
</p>
<p>Otherwise</p>
</blockquote>
<p><b>Rationale:</b></p>
<p>It's clear what we wanted to say, we just failed to say it. This
fixes it.</p>
<hr>
<a name="379"><h3>379.&nbsp;nonsensical ctype::do_widen() requirement</h3></a><p><b>Section:</b>&nbsp;22.2.1.1.2 <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lib-locales.html#lib.locale.ctype.virtuals"> [lib.locale.ctype.virtuals]</a>&nbsp; <b>Status:</b>&nbsp;<a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#WP">WP</a>&nbsp; <b>Submitter:</b>&nbsp;Martin Sebor&nbsp; <b>Date:</b>&nbsp;6 Sep 2002</p>
<p>
The last sentence in 22.2.1.1.2, p11 below doesn't seem to make sense.
@ -11651,6 +12027,64 @@ Change the guarantee to "postcondition: r is dereferenceable."
<p><b>Rationale:</b></p>
<p>Fixes an obvious typo</p>
<hr>
<a name="384"><h3>384.&nbsp;equal_range has unimplementable runtime complexity</h3></a><p><b>Section:</b>&nbsp;25.3.3.3 <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lib-algorithms.html#lib.equal.range"> [lib.equal.range]</a>&nbsp; <b>Status:</b>&nbsp;<a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#WP">WP</a>&nbsp; <b>Submitter:</b>&nbsp;Hans Bos&nbsp; <b>Date:</b>&nbsp;18 Oct 2002</p>
<p>
Section 25.3.3.3 <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lib-algorithms.html#lib.equal.range"> [lib.equal.range]</a>
states that at most 2 * log(last - first) + 1
comparisons are allowed for equal_range.
</p>
<p>It is not possible to implement equal_range with these constraints.</p>
<p>In a range of one element as in:</p>
<pre> int x = 1;
equal_range(&amp;x, &amp;x + 1, 1)
</pre>
<p>it is easy to see that at least 2 comparison operations are needed.</p>
<p>For this case at most 2 * log(1) + 1 = 1 comparison is allowed.</p>
<p>I have checked a few libraries and they all use the same (nonconforming)
algorithm for equal_range that has a complexity of</p>
<pre> 2* log(distance(first, last)) + 2.
</pre>
<p>I guess this is the algorithm that the standard assumes for equal_range.</p>
<p>
It is easy to see that 2 * log(distance) + 2 comparisons are enough
since equal range can be implemented with lower_bound and upper_bound
(both log(distance) + 1).
</p>
<p>
I think it is better to require something like 2log(distance) + O(1) (or
even logarithmic as multiset::equal_range).
Then an implementation has more room to optimize for certain cases (e.g.
have log(distance) characteristics when at most match is found in the range
but 2log(distance) + 4 for the worst case).
</p>
<p><b>Proposed resolution:</b></p>
<p>In 25.3.3.1 <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lib-algorithms.html#lib.lower.bound"> [lib.lower.bound]</a>/4, change <tt>log(last - first) + 1</tt>
to <tt>log<sub>2</sub>(last - first) + <i>O</i>(1)</tt>.</p>
<p>In 25.3.3.2 <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lib-algorithms.html#lib.upper.bound"> [lib.upper.bound]</a>/4, change <tt>log(last - first) + 1</tt>
to <tt>log<sub>2</sub>(last - first) + <i>O</i>(1)</tt>.</p>
<p>In 25.3.3.3 <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lib-algorithms.html#lib.equal.range"> [lib.equal.range]</a>/4, change <tt>2*log(last - first) + 1</tt>
to <tt>2*log<sub>2</sub>(last - first) + <i>O</i>(1)</tt>.</p>
<p><i>[Matt provided wording]</i></p>
<p><b>Rationale:</b></p>
<p>The LWG considered just saying <i>O</i>(log n) for all three, but
Ê decided that threw away too much valuable information.Ê The fact
Ê that lower_bound is twice as fast as equal_range is important.
Ê However, it's better to allow an arbitrary additive constant than to
Ê specify an exact count.Ê An exact count would have to
Ê involve <tt>floor</tt> or <tt>ceil</tt>.Ê It would be too easy to
Ê get this wrong, and don't provide any substantial value for users.</p>
<hr>
<a name="386"><h3>386.&nbsp;Reverse iterator's operator[] has impossible return type</h3></a><p><b>Section:</b>&nbsp;24.4.1.3.11 <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lib-iterators.html#lib.reverse.iter.opindex"> [lib.reverse.iter.opindex]</a>&nbsp; <b>Status:</b>&nbsp;<a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#DR">DR</a>&nbsp; <b>Submitter:</b>&nbsp;Matt Austern&nbsp; <b>Date:</b>&nbsp;23 Oct 2002</p>
<p>In 24.4.1.3.11 <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lib-iterators.html#lib.reverse.iter.opindex"> [lib.reverse.iter.opindex]</a>, <tt>reverse_iterator&lt;&gt;::operator[]</tt>
is specified as having a return type of <tt>reverse_iterator::reference</tt>,
@ -13216,7 +13650,7 @@ In section 27.6.2.3 <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lib-ios
of <tt>sentry::operator bool()</tt> to const.
</p>
<hr>
<a name="443"></a><h3><a name="443">443.&nbsp;filebuf::close() inconsistent use of EOF</a></h3><p><b>Section:</b>&nbsp;27.8.1.3 <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lib-iostreams.html#lib.filebuf.members"> [lib.filebuf.members]</a>&nbsp; <b>Status:</b>&nbsp;<a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#WP">WP</a>&nbsp; <b>Submitter:</b>&nbsp;Vincent Leloup&nbsp; <b>Date:</b>&nbsp;20 Nov 2003</p>
<a name="443"><h3>443.&nbsp;filebuf::close() inconsistent use of EOF</h3></a><p><b>Section:</b>&nbsp;27.8.1.3 <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lib-iostreams.html#lib.filebuf.members"> [lib.filebuf.members]</a>&nbsp; <b>Status:</b>&nbsp;<a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#WP">WP</a>&nbsp; <b>Submitter:</b>&nbsp;Vincent Leloup&nbsp; <b>Date:</b>&nbsp;20 Nov 2003</p>
<p>
In section 27.8.1.3 <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lib-iostreams.html#lib.filebuf.members"> [lib.filebuf.members]</a> par6, in effects description of
basic_filebuf&lt;charT, traits&gt;::close(), overflow(EOF) is used twice;
@ -13888,6 +14322,194 @@ value of widen(c) is otherwise.
I propose to strike the Footnote.
</p>
<hr>
<a name="475"><h3>475.&nbsp;May the function object passed to for_each modify the elements of the iterated sequence?</h3></a><p><b>Section:</b>&nbsp;25.1.1 <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lib-algorithms.html#lib.alg.foreach"> [lib.alg.foreach]</a>&nbsp; <b>Status:</b>&nbsp;<a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#WP">WP</a>&nbsp; <b>Submitter:</b>&nbsp;Stephan T. Lavavej, Jaakko Jarvi&nbsp; <b>Date:</b>&nbsp;9 Jul 2004</p>
<p>
It is not clear whether the function object passed to for_each is allowed to
modify the elements of the sequence being iterated over.
</p>
<p>
for_each is classified without explanation in [lib.alg.nonmodifying], "25.1
Non-modifying sequence operations". 'Non-modifying sequence operation' is
never defined.
</p>
<p>
25(5) says: "If an algorithm's Effects section says that a value pointed to
by any iterator passed as an argument is modified, then that algorithm has
an additional type requirement: The type of that argument shall satisfy the
requirements of a mutable iterator (24.1)."
</p>
<p>for_each's Effects section does not mention whether arguments can be
modified:</p>
<blockquote>
"Effects: Applies f to the result of dereferencing every iterator in the
range [first, last), starting from first and proceeding to last - 1."
</blockquote>
<p>
Every other algorithm in [lib.alg.nonmodifying] is "really" non-modifying in
the sense that neither the algorithms themselves nor the function objects
passed to the algorithms may modify the sequences or elements in any way.
This DR affects only for_each.
</p>
<p>
We suspect that for_each's classification in "non-modifying sequence
operations" means that the algorithm itself does not inherently modify the
sequence or the elements in the sequence, but that the function object
passed to it may modify the elements it operates on.
</p>
<p>
The original STL document by Stepanov and Lee explicitly prohibited the
function object from modifying its argument.
The "obvious" implementation of for_each found in several standard library
implementations, however, does not impose this restriction.
As a result, we suspect that the use of for_each with function objects that modify
their arguments is wide-spread.
If the restriction was reinstated, all such code would become non-conforming.
Further, none of the other algorithms in the Standard
could serve the purpose of for_each (transform does not guarantee the order in
which its function object is called).
</p>
<p>
We suggest that the standard be clarified to explicitly allow the function object
passed to for_each modify its argument.</p>
<p><b>Proposed resolution:</b></p>
<p>Add a nonnormative note to the Effects in 25.1.1 <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lib-algorithms.html#lib.alg.foreach"> [lib.alg.foreach]</a>: If
the type of 'first' satisfies the requirements of a mutable iterator,
'f' may apply nonconstant functions through the dereferenced iterators
passed to it.
</p>
<p><b>Rationale:</b></p>
<p>The LWG believes that nothing in the standard prohibits function
objects that modify the sequence elements. The problem is that
for_each is in a secion entitled "nonmutating algorithms", and the
title may be confusing. A nonnormative note should clarify that.</p>
<hr>
<a name="478"><h3>478.&nbsp;Should forward iterator requirements table have a line for r-&gt;m?</h3></a><p><b>Section:</b>&nbsp;24.1.3 <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lib-iterators.html#lib.forward.iterators"> [lib.forward.iterators]</a>&nbsp; <b>Status:</b>&nbsp;<a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#WP">WP</a>&nbsp; <b>Submitter:</b>&nbsp;Dave Abrahams&nbsp; <b>Date:</b>&nbsp;11 Jul 2004</p>
<p>
The Forward Iterator requirements table contains the following:
</p>
<pre> expression return type operational precondition
semantics
========== ================== =========== ==========================
a-&gt;m U&amp; if X is mutable, (*a).m pre: (*a).m is well-defined.
otherwise const U&amp;
r-&gt;m U&amp; (*r).m pre: (*r).m is well-defined.
</pre>
<p>The second line may be unnecessary. Paragraph 11 of
[lib.iterator.requirements] says:
</p>
<blockquote>
In the following sections, a and b denote values of type const X, n
denotes a value of the difference type Distance, u, tmp, and m
denote identifiers, r denotes a value of X&amp;, t denotes a value of
value type T, o denotes a value of some type that is writable to
the output iterator.
</blockquote>
<p>
Because operators can be overloaded on an iterator's const-ness, the
current requirements allow iterators to make many of the operations
specified using the identifiers a and b invalid for non-const
iterators.</p>
<p>Related issue: <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-closed.html#477">477</a></p>
<p><b>Proposed resolution:</b></p>
<p>Remove the "r-&gt;m" line from the Forward Iterator requirements
table. Change</p>
<blockquote>
"const X"
</blockquote>
<p> to </p>
<blockquote>
"X or const X"
</blockquote>
<p>in paragraph 11 of [lib.iterator.requirements].</p>
<p><b>Rationale:</b></p>
<p>
This is a defect because it constrains an lvalue to returning a modifiable lvalue.
</p>
<hr>
<a name="495"><h3>495.&nbsp;Clause 22 template parameter requirements</h3></a><p><b>Section:</b>&nbsp;22 <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lib-locales.html#lib.localization"> [lib.localization]</a>&nbsp; <b>Status:</b>&nbsp;<a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#WP">WP</a>&nbsp; <b>Submitter:</b>&nbsp;Beman Dawes&nbsp; <b>Date:</b>&nbsp;10 Jan 2005</p>
<p>It appears that there are no requirements specified for many of the
template parameters in clause 22. It looks like this issue has never
come up, except perhaps for Facet.</p>
<p>Clause 22 isn't even listed in 17.3.2.1 [lib.type.descriptions],
either, which is the wording that allows requirements on template
parameters to be identified by name.</p>
<p>So one issue is that 17.3.2.1 [lib.type.descriptions] Should be
changed to cover clause 22. A better change, which will cover us in
the future, would be to say that it applies to all the library
clauses. Then if a template gets added to any library clause we are
covered.</p>
<p>charT, InputIterator, and other names with requirements defined
elsewhere are fine, assuming the 17.3.2.1 [lib.type.descriptions] fix.
But there are a few template arguments names which I don't think have
requirements given elsewhere:</p>
<ul>
<li>internT and externT. The fix is to add wording saying that internT
and externT must meet the same requirements as template arguments
named charT.</li>
<li>stateT. I'm not sure about this one. There already is some wording,
but it seems a bit vague.</li>
<li>Intl. [lib.locale.moneypunct.byname] The fix for this one is to
rename "Intl" to "International". The name is important because other
text identifies the requirements for the name International but not
for Intl.</li>
</ul>
<p><b>Proposed resolution:</b></p>
<p>Change 17.3.2.1 <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lib-intro.html#lib.type.descriptions"> [lib.type.descriptions]</a>, paragraph 1, from:</p>
<blockquote>
The Requirements subclauses may describe names that are used to
specify constraints on template arguments.153) These names are used in
clauses 20, 23, 25, and 26 to describe the types that may be supplied
as arguments by a C++ program when instantiating template components
from the library.
</blockquote>
<p>to:</p>
<blockquote>
The Requirements subclauses may describe names that are used to
specify constraints on template arguments.153) These names are used in
library clauses to describe the types that may be supplied as
arguments by a C++ program when instantiating template components from
the library.
</blockquote>
<p>In the front matter of class 22, locales, add:</p>
<blockquote>
Template parameter types internT and externT shall meet the
requirements of charT (described in 21 <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lib-strings.html#lib.strings"> [lib.strings]</a>).
</blockquote>
<p><b>Rationale:</b></p>
<p>
Again, a blanket clause isn't blanket enough. Also, we've got a
couple of names that we don't have blanket requirement statements
for. The only issue is what to do about stateT. This wording is
thin, but probably adequate.</p>
<hr>
<a name="496"><h3>496.&nbsp;Illegal use of "T" in vector&lt;bool&gt;</h3></a><p><b>Section:</b>&nbsp;23.2.5 <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lib-containers.html#lib.vector.bool"> [lib.vector.bool]</a>&nbsp; <b>Status:</b>&nbsp;<a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#WP">WP</a>&nbsp; <b>Submitter:</b>&nbsp;richard@ex-parrot.com&nbsp; <b>Date:</b>&nbsp;10 Feb 2005</p>
<p>
In the synopsis of the std::vector&lt;bool&gt; specialisation in 23.2.5 <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lib-containers.html#lib.vector.bool"> [lib.vector.bool]</a>,
@ -13900,6 +14522,210 @@ the non-template assign() function has the signature</p>
<p><b>Proposed resolution:</b></p>
<p>Replace "T" with "value_type".</p>
<hr>
<a name="497"><h3>497.&nbsp;meaning of numeric_limits::traps for floating point types</h3></a><p><b>Section:</b>&nbsp;18.2.1.2 <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lib-support.html#lib.numeric.limits.members"> [lib.numeric.limits.members]</a>&nbsp; <b>Status:</b>&nbsp;<a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#WP">WP</a>&nbsp; <b>Submitter:</b>&nbsp;Martin Sebor&nbsp; <b>Date:</b>&nbsp;2 Mar 2005</p>
<p>18.2.1.2, p59 says this much about the traps member of numeric_limits:</p>
<blockquote>
<p>static const bool traps;<br>
-59- true if trapping is implemented for the type.204)
<br>
Footnote 204: Required by LIA-1.
</p>
</blockquote>
<p>It's not clear what is meant by "is implemented" here.</p>
<p>
In the context of floating point numbers it seems reasonable to expect
to be able to use traps to determine whether a program can "safely" use
infinity(), quiet_NaN(), etc., in arithmetic expressions, that is
without causing a trap (i.e., on UNIX without having to worry about
getting a signal). When traps is true, I would expect any of the
operations in section 7 of IEEE 754 to cause a trap (and my program
to get a SIGFPE). So, for example, on Alpha, I would expect traps
to be true by default (unless I compiled my program with the -ieee
option), false by default on most other popular architectures,
including IA64, MIPS, PA-RISC, PPC, SPARC, and x86 which require
traps to be explicitly enabled by the program.
</p>
<p>
Another possible interpretation of p59 is that traps should be true
on any implementation that supports traps regardless of whether they
are enabled by default or not. I don't think such an interpretation
makes the traps member very useful, even though that is how traps is
implemented on several platforms. It is also the only way to implement
traps on platforms that allow programs to enable and disable trapping
at runtime.
</p>
<p><b>Proposed resolution:</b></p>
<p>Change p59 to read:</p>
<blockquote>True if, at program startup, there exists a value of the type that
would cause an arithmetic operation using that value to trap.</blockquote>
<p><b>Rationale:</b></p>
<p>
Real issue, since trapping can be turned on and off. Unclear what a
static query can say about a dynamic issue. The real advice we should
give users is to use cfenv for these sorts of queries. But this new
proposed resolution is at least consistent and slightly better than
nothing.</p>
<hr>
<a name="505"><h3>505.&nbsp;Result_type in random distribution requirements</h3></a><p><b>Section:</b>&nbsp;TR1 5.1.1 <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/tr1.html#tr.rand.req"> [tr.rand.req]</a>&nbsp; <b>Status:</b>&nbsp;<a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#WP">WP</a>&nbsp; <b>Submitter:</b>&nbsp;Walter Brown&nbsp; <b>Date:</b>&nbsp;3 Jul 2005</p>
<p>
Table 17: Random distribution requirements
</p>
<p>
Row 1 requires that each random distribution provide a nested type "input_type";
this type denotes the type of the values that the distribution consumes.
</p>
<p>
Inspection of all distributions in [tr.rand.dist] reveals that each distribution
provides a second typedef ("result_type") that denotes the type of the values the
distribution produces when called.
</p>
<p><b>Proposed resolution:</b></p>
<p>
It seems to me that this is also a requirement
for all distributions and should therefore be indicated as such via a new second
row to this table 17:
</p>
<table border="1" cellpadding="5">
<tbody><tr>
<td>X::result_type</td>
<td>T</td>
<td>---</td>
<td>compile-time</td>
</tr>
</tbody></table>
<p><i>[
Berlin: Voted to WP. N1932 adopts the proposed resolution: see Table 5 row 1.
]</i></p>
<hr>
<a name="507"><h3>507.&nbsp;Missing requirement for variate_generator::operator()</h3></a><p><b>Section:</b>&nbsp;TR1 5.1.3 <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/tr1.html#tr.rand.var"> [tr.rand.var]</a>&nbsp; <b>Status:</b>&nbsp;<a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#WP">WP</a>&nbsp; <b>Submitter:</b>&nbsp;Walter Brown&nbsp; <b>Date:</b>&nbsp;3 Jul 2005</p>
<p>
Paragraph 11 of [tr.rand.var] equires that the member template
</p>
<blockquote><pre>template&lt;class T&gt; result_type operator() (T value);
</pre></blockquote>
<p>
return
</p>
<blockquote><pre>distribution()(e, value)
</pre></blockquote>
<p>
However, not all distributions have an operator() with a corresponding signature.
</p>
<p><i>[
Berlin: As a working group we voted in favor of N1932 which makes this moot:
variate_generator has been eliminated. Then in full committee we voted to give
this issue WP status (mistakenly).
]</i></p>
<p><b>Proposed resolution:</b></p>
<p>
We therefore recommend that we insert the following precondition before paragraph 11:
</p>
<blockquote>
Precondition: <tt>distribution().operator()(e,value)</tt> is well-formed.
</blockquote>
<hr>
<a name="508"><h3>508.&nbsp;Bad parameters for ranlux64_base_01</h3></a><p><b>Section:</b>&nbsp;TR1 5.1.5 <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/tr1.html#tr.rand.predef"> [tr.rand.predef]</a>&nbsp; <b>Status:</b>&nbsp;<a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#WP">WP</a>&nbsp; <b>Submitter:</b>&nbsp;Walter Brown&nbsp; <b>Date:</b>&nbsp;3 Jul 2005</p>
<p>
The fifth of these engines with predefined parameters, ranlux64_base_01,
appears to have an unintentional error for which there is a simple correction.
The two pre-defined subtract_with_carry_01 engines are given as:
</p>
<blockquote><pre>typedef subtract_with_carry_01&lt;float, 24, 10, 24&gt; ranlux_base_01;
typedef subtract_with_carry_01&lt;double, 48, 10, 24&gt; ranlux64_base_01;
</pre></blockquote>
<p>
We demonstrate below that ranlux64_base_01 fails to meet the intent of the
random number generation proposal, but that the simple correction to
</p>
<blockquote><pre>typedef subtract_with_carry_01&lt;double, 48, 5, 12&gt; ranlux64_base_01;
</pre></blockquote>
<p>
does meet the intent of defining well-known good parameterizations.
</p>
<p>
The ranlux64_base_01 engine as presented fails to meet the intent for
predefined engines, stated in proposal N1398 (section E):
</p>
<blockquote><p>
In order to make good random numbers available to a large number of library
users, this proposal not only defines generic random-number engines, but also
provides a number of predefined well-known good parameterizations for those.
</p></blockquote>
<p>
The predefined ranlux_base_01 engine has been proven [1,2,3] to have a very
long period and so meets this criterion. This property makes it suitable for
use in the excellent discard_block engines defined subsequently. The proof
of long period relies on the fact (proven in [1]) that 2**(w*r) - 2**(w*s)
+ 1 is prime (w, r, and s are template parameters to subtract_with_carry_01,
as defined in [tr.rand.eng.sub1]).
</p>
<p>
The ranlux64_base_01 engine as presented in [tr.rand.predef] uses w=48, r=24, s=10.
For these numbers, the combination 2**(w*r)-2**(w*s)+1 is non-prime (though
explicit factorization would be a challenge). In consequence, while it is
certainly possible for some seeding states that this engine would have a very
long period, it is not at all Òwell-knownÓ that this is the case. The intent
in the N1398 proposal involved the base of the ranlux64 engine, which finds heavy
use in the physics community. This is isomorphic to the predefined ranlux_base_01,
but exploits the ability of double variables to hold (at least) 48 bits of mantissa,
to deliver 48 random bits at a time rather than 24.
</p>
<p><b>Proposed resolution:</b></p>
<p>
To achieve this intended behavior, the correct template parameteriztion would be:
</p>
<blockquote><pre>typedef subtract_with_carry_01&lt;double, 48, 5, 12&gt; ranlux64_base_01;
</pre></blockquote>
<p>
The sequence of mantissa bits delivered by this is isomorphic (treating each
double as having the bits of two floats) to that delivered by ranlux_base_01.
</p>
<p>
<b>References:</b>
</p>
<ol>
<li>F. James, Comput. Phys. Commun. 60(1990) 329</li>
<li>G. Marsaglia and A. Zaman, Ann. Appl. Prob 1(1991) 462</li>
<li>M. Luscher, Comput. Phys. Commun. 79(1994) 100-110</li>
</ol>
<p><i>[
Berlin: Voted to WP. N1932 adopts the proposed resolution in 26.3.5,
just above paragraph 5.
]</i></p>
<hr>
<a name="519"><h3>519.&nbsp;Data() undocumented</h3></a><p><b>Section:</b>&nbsp;TR1 6.2.2 <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/tr1.html#tr.array.array"> [tr.array.array]</a>&nbsp; <b>Status:</b>&nbsp;<a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#WP">WP</a>&nbsp; <b>Submitter:</b>&nbsp;Pete Becker&nbsp; <b>Date:</b>&nbsp;3 Jul 2005</p>
<p>
<tt>array&lt;&gt;::data()</tt> is present in the class synopsis, but not documented.
</p>
<p><b>Proposed resolution:</b></p>
<p>
Add a new section, after 6.2.2.3:
</p>
<blockquote><pre>T* data()
const T* data() const;
</pre></blockquote>
<p>
<b>Returns:</b> <tt>elems</tt>.
</p>
<p>
Change 6.2.2.4/2 to:
</p>
<blockquote>
In the case where <tt>N == 0</tt>, <tt>begin() == end()</tt>. The return value
of <tt>data()</tt> is unspecified.
</blockquote>
<hr>
<a name="533"><h3>533.&nbsp;typo in 2.2.3.10/1</h3></a><p><b>Section:</b>&nbsp;TR1 2.2.3.10 <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/tr1.html#tr.util.smartptr.getdeleter"> [tr.util.smartptr.getdeleter]</a>&nbsp; <b>Status:</b>&nbsp;<a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#DR">DR</a>&nbsp; <b>Submitter:</b>&nbsp;Paolo Carlini&nbsp; <b>Date:</b>&nbsp;9 Nov 2005</p>
<p>
I'm seeing something that looks like a typo. The Return of <tt>get_deleter</tt>