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<td align="left">Doc. no.</td>
<td align="left">N1764=05-0024</td>
</tr>
<tr>
<td align="left">Date:</td>
<td align="left">2005-03-04</td>
</tr>
<tr>
<td align="left">Project:</td>
<td align="left">Programming Language C++</td>
</tr>
<tr>
<td align="left">Reply to:</td>
<td align="left">Matt Austern &lt;austern@google.com&gt;</td>
</tr>
</table>
<h1>C++ Standard Library Closed Issues List (Revision 35)</h1>
  <p>Reference ISO/IEC IS 14882:1998(E)</p>
  <p>Also see:</p>
    <ul>
      <li>
<a href="lwg-toc.html">Table of Contents</a> for all library issues.</li>
      <li>
<a href="lwg-index.html">Index by Section</a> for all library issues.</li>
      <li>
<a href="lwg-status.html">Index by Status</a> for all library issues.</li>
      <li><a href="lwg-active.html">Library Active Issues List</a></li>
      <li><a href="lwg-defects.html">Library Defect Reports List</a></li>
    </ul>

  <p>This document contains only library issues which have been closed
  by the Library Working Group as duplicates or not defects. That is,
  issues which have a status of <a href="lwg-active.html#Dup">Dup</a> or <a href="lwg-active.html#NAD">NAD</a>. See the <a href="lwg-active.html">Library Active Issues List</a> active issues and more
  information. See the <a href="lwg-defects.html">Library Defect Reports List</a> for issues considered
  defects.  The introductory material in that document also applies to
  this document.</p>
<h2>Revision History</h2>
<ul>
<li>R35: 
2005-03 pre-Lillehammer mailing.
</li>
<li>R34: 
2005-01 mid-term mailing.  Added new issues <a href="lwg-active.html#488">488</a>-<a href="lwg-active.html#494">494</a>.
</li>
<li>R33: 
2004-11 post-Redmond mailing.  Reflections actions taken in Redmond.
</li>
<li>R32: 
2004-09 pre-Redmond mailing: reflects new proposed resolutions and
new issues received after the 2004-07 mailing.  Added
new issues <a href="lwg-active.html#479">479</a>-<a href="lwg-active.html#481">481</a>.
</li>
<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="lwg-active.html#463">463</a>-<a href="lwg-active.html#478">478</a>.
</li>
<li>R30: 
Post-Sydney mailing: reflects decisions made at the Sydney meeting.
Voted all "Ready" issues from R29 into the working paper.
Added new issues <a href="lwg-active.html#460">460</a>-<a href="lwg-active.html#462">462</a>.
</li>
<li>R29: 
Pre-Sydney mailing.  Added new issues <a href="lwg-defects.html#441">441</a>-<a href="lwg-active.html#457">457</a>.
</li>
<li>R28: 
Post-Kona mailing: reflects decisions made at the Kona meeting.
Added new issues <a href="lwg-defects.html#432">432</a>-<a href="lwg-closed.html#440">440</a>.
</li>
<li>R27: 
Pre-Kona mailing.  Added new issues <a href="lwg-defects.html#404">404</a>-<a href="lwg-active.html#431">431</a>.
</li>
<li>R26: 
Post-Oxford mailing: reflects decisions made at the Oxford meeting.
All issues in Ready status were voted into DR status.  All issues in
DR status were voted into WP status.
</li>
<li>R25: 
Pre-Oxford mailing.  Added new issues <a href="lwg-closed.html#390">390</a>-<a href="lwg-defects.html#402">402</a>.
</li>
<li>R24: 
Post-Santa Cruz mailing: reflects decisions made at the Santa Cruz
meeting.  All Ready issues from R23 with the exception of <a href="lwg-defects.html#253">253</a>, which has been given a new proposed resolution, were
moved to DR status.  Added new issues <a href="lwg-defects.html#383">383</a>-<a href="lwg-defects.html#389">389</a>.  (Issues <a href="lwg-active.html#387">387</a>-<a href="lwg-defects.html#389">389</a> were discussed
at the meeting.)  Made progress on issues <a href="lwg-defects.html#225">225</a>, <a href="lwg-defects.html#226">226</a>, <a href="lwg-defects.html#229">229</a>: <a href="lwg-defects.html#225">225</a> and <a href="lwg-defects.html#229">229</a> have been moved to Ready status, and the only remaining
concerns with <a href="lwg-defects.html#226">226</a> involve wording.
</li>
<li>R23: 
Pre-Santa Cruz mailing.  Added new issues <a href="lwg-closed.html#367">367</a>-<a href="lwg-active.html#382">382</a>.
Moved issues in the TC to TC status.
</li>
<li>R22: 
Post-Cura&ccedil;ao mailing.  Added new issues <a href="lwg-active.html#362">362</a>-<a href="lwg-active.html#366">366</a>.
</li>
<li>R21: 
Pre-Cura&ccedil;ao mailing.  Added new issues <a href="lwg-closed.html#351">351</a>-<a href="lwg-closed.html#361">361</a>.
</li>
<li>R20: 
Post-Redmond mailing; reflects actions taken in Redmond.  Added
new issues <a href="lwg-defects.html#336">336</a>-<a href="lwg-closed.html#350">350</a>, of which issues 
<a href="lwg-defects.html#347">347</a>-<a href="lwg-closed.html#350">350</a> were added since Redmond, hence
not discussed at the meeting.  

All Ready issues were moved to DR status, with the exception of issues
<a href="lwg-defects.html#284">284</a>, <a href="lwg-defects.html#241">241</a>, and <a href="lwg-closed.html#267">267</a>.

Noteworthy issues discussed at Redmond include 
<a href="lwg-defects.html#120">120</a> <a href="lwg-defects.html#202">202</a>, <a href="lwg-defects.html#226">226</a>, <a href="lwg-active.html#233">233</a>, 
<a href="lwg-defects.html#270">270</a>, <a href="lwg-defects.html#253">253</a>, <a href="lwg-active.html#254">254</a>, <a href="lwg-closed.html#323">323</a>.
</li>
<li>R19: 
Pre-Redmond mailing.  Added new issues 
<a href="lwg-closed.html#323">323</a>-<a href="lwg-defects.html#335">335</a>.
</li>
<li>R18: 
Post-Copenhagen mailing; reflects actions taken in Copenhagen.
Added new issues <a href="lwg-defects.html#312">312</a>-<a href="lwg-defects.html#317">317</a>, and discussed
new issues <a href="lwg-defects.html#271">271</a>-<a href="lwg-closed.html#314">314</a>.

Changed status of issues
<a href="lwg-defects.html#103">103</a> <a href="lwg-defects.html#118">118</a> <a href="lwg-defects.html#136">136</a> <a href="lwg-defects.html#153">153</a>
<a href="lwg-defects.html#165">165</a> <a href="lwg-defects.html#171">171</a> <a href="lwg-defects.html#183">183</a> <a href="lwg-defects.html#184">184</a>
<a href="lwg-defects.html#185">185</a> <a href="lwg-defects.html#186">186</a> <a href="lwg-defects.html#214">214</a> <a href="lwg-defects.html#221">221</a>
<a href="lwg-defects.html#234">234</a> <a href="lwg-defects.html#237">237</a> <a href="lwg-defects.html#243">243</a> <a href="lwg-defects.html#248">248</a>
<a href="lwg-defects.html#251">251</a> <a href="lwg-defects.html#252">252</a> <a href="lwg-defects.html#256">256</a> <a href="lwg-defects.html#260">260</a>
<a href="lwg-defects.html#261">261</a> <a href="lwg-defects.html#262">262</a> <a href="lwg-defects.html#263">263</a> <a href="lwg-defects.html#265">265</a>
<a href="lwg-defects.html#268">268</a>
to DR.

Changed status of issues
<a href="lwg-defects.html#49">49</a>  <a href="lwg-defects.html#109">109</a> <a href="lwg-defects.html#117">117</a> <a href="lwg-defects.html#182">182</a>
<a href="lwg-defects.html#228">228</a> <a href="lwg-defects.html#230">230</a> <a href="lwg-defects.html#232">232</a> <a href="lwg-defects.html#235">235</a>
<a href="lwg-defects.html#238">238</a> <a href="lwg-defects.html#241">241</a> <a href="lwg-defects.html#242">242</a> <a href="lwg-defects.html#250">250</a>
<a href="lwg-defects.html#259">259</a> <a href="lwg-defects.html#264">264</a> <a href="lwg-defects.html#266">266</a> <a href="lwg-closed.html#267">267</a>
<a href="lwg-defects.html#271">271</a> <a href="lwg-defects.html#272">272</a> <a href="lwg-defects.html#273">273</a> <a href="lwg-defects.html#275">275</a>
<a href="lwg-defects.html#281">281</a> <a href="lwg-defects.html#284">284</a> <a href="lwg-defects.html#285">285</a> <a href="lwg-defects.html#286">286</a>
<a href="lwg-defects.html#288">288</a> <a href="lwg-defects.html#292">292</a> <a href="lwg-defects.html#295">295</a> <a href="lwg-defects.html#297">297</a>
<a href="lwg-defects.html#298">298</a> <a href="lwg-defects.html#301">301</a> <a href="lwg-defects.html#303">303</a> <a href="lwg-defects.html#306">306</a>
<a href="lwg-defects.html#307">307</a> <a href="lwg-defects.html#308">308</a> <a href="lwg-defects.html#312">312</a>
to Ready.

Closed issues 
<a href="lwg-closed.html#111">111</a> <a href="lwg-closed.html#277">277</a> <a href="lwg-closed.html#279">279</a> <a href="lwg-closed.html#287">287</a>
<a href="lwg-closed.html#289">289</a> <a href="lwg-closed.html#293">293</a> <a href="lwg-closed.html#302">302</a> <a href="lwg-closed.html#313">313</a>
<a href="lwg-closed.html#314">314</a>
as NAD.

</li>
<li>R17: 
Pre-Copenhagen mailing.  Converted issues list to XML.  Added proposed
resolutions for issues <a href="lwg-defects.html#49">49</a>, <a href="lwg-defects.html#76">76</a>, <a href="lwg-defects.html#91">91</a>, <a href="lwg-defects.html#235">235</a>, <a href="lwg-defects.html#250">250</a>, <a href="lwg-closed.html#267">267</a>.
Added new issues <a href="lwg-defects.html#278">278</a>-<a href="lwg-defects.html#311">311</a>.
</li>
<li>R16:  
post-Toronto mailing; reflects actions taken in Toronto. Added new
issues <a href="lwg-defects.html#265">265</a>-<a href="lwg-closed.html#277">277</a>.  Changed status of issues
<a href="lwg-defects.html#3">3</a>, <a href="lwg-defects.html#8">8</a>, <a href="lwg-defects.html#9">9</a>, <a href="lwg-defects.html#19">19</a>,
<a href="lwg-defects.html#26">26</a>, <a href="lwg-defects.html#31">31</a>, <a href="lwg-defects.html#61">61</a>,
<a href="lwg-defects.html#63">63</a>, <a href="lwg-defects.html#86">86</a>, <a href="lwg-defects.html#108">108</a>,
<a href="lwg-defects.html#112">112</a>, <a href="lwg-defects.html#114">114</a>, <a href="lwg-defects.html#115">115</a>,
<a href="lwg-defects.html#122">122</a>, <a href="lwg-defects.html#127">127</a>, <a href="lwg-defects.html#129">129</a>,
<a href="lwg-defects.html#134">134</a>, <a href="lwg-defects.html#137">137</a>, <a href="lwg-defects.html#142">142</a>,
<a href="lwg-defects.html#144">144</a>, <a href="lwg-defects.html#146">146</a>, <a href="lwg-defects.html#147">147</a>,
<a href="lwg-defects.html#159">159</a>, <a href="lwg-defects.html#164">164</a>, <a href="lwg-defects.html#170">170</a>,
<a href="lwg-defects.html#181">181</a>, <a href="lwg-defects.html#199">199</a>, <a href="lwg-defects.html#208">208</a>,
<a href="lwg-defects.html#209">209</a>, <a href="lwg-defects.html#210">210</a>, <a href="lwg-defects.html#211">211</a>,
<a href="lwg-defects.html#212">212</a>, <a href="lwg-defects.html#217">217</a>, <a href="lwg-defects.html#220">220</a>,
<a href="lwg-defects.html#222">222</a>, <a href="lwg-defects.html#223">223</a>, <a href="lwg-defects.html#224">224</a>,
<a href="lwg-defects.html#227">227</a> to "DR".  Reopened issue <a href="lwg-active.html#23">23</a>. Reopened
issue <a href="lwg-defects.html#187">187</a>. Changed issues <a href="lwg-closed.html#2">2</a> and
<a href="lwg-closed.html#4">4</a> to NAD. Fixed a typo in issue <a href="lwg-defects.html#17">17</a>. Fixed
issue <a href="lwg-defects.html#70">70</a>: signature should be changed both places it
appears. Fixed issue <a href="lwg-defects.html#160">160</a>: previous version didn't fix
the bug in enough places.
</li>
<li>R15: 
pre-Toronto mailing. Added issues
<a href="lwg-active.html#233">233</a>-<a href="lwg-defects.html#264">264</a>. Some small HTML formatting
changes so that we pass Weblint tests.
</li>
<li>R14: 
post-Tokyo II mailing; reflects committee actions taken in
Tokyo. Added issues <a href="lwg-defects.html#228">228</a> to <a href="lwg-defects.html#232">232</a>. (00-0019R1/N1242)
</li>
<li>R13: 
pre-Tokyo II updated: Added issues <a href="lwg-defects.html#212">212</a> to <a href="lwg-defects.html#227">227</a>.
</li>
<li>R12: 
pre-Tokyo II mailing: Added issues <a href="lwg-defects.html#199">199</a> to
<a href="lwg-defects.html#211">211</a>. Added "and paragraph 5" to the proposed resolution
of issue <a href="lwg-defects.html#29">29</a>.  Add further rationale to issue
<a href="lwg-closed.html#178">178</a>.
</li>
<li>R11: 
post-Kona mailing: Updated to reflect LWG and full committee actions
in Kona (99-0048/N1224). Note changed resolution of issues
<a href="lwg-closed.html#4">4</a> and <a href="lwg-defects.html#38">38</a>. Added issues <a href="lwg-closed.html#196">196</a>
to <a href="lwg-defects.html#198">198</a>. Closed issues list split into "defects" and
"closed" documents.  Changed the proposed resolution of issue
<a href="lwg-closed.html#4">4</a> to NAD, and changed the wording of proposed resolution
of issue <a href="lwg-defects.html#38">38</a>.
</li>
<li>R10: 
pre-Kona updated.  Added proposed resolutions <a href="lwg-defects.html#83">83</a>,
<a href="lwg-defects.html#86">86</a>, <a href="lwg-defects.html#91">91</a>, <a href="lwg-defects.html#92">92</a>,
<a href="lwg-defects.html#109">109</a>. Added issues <a href="lwg-closed.html#190">190</a> to
<a href="lwg-defects.html#195">195</a>. (99-0033/D1209, 14 Oct 99)
</li>
<li>R9: 
pre-Kona mailing.  Added issues <a href="lwg-closed.html#140">140</a> to
<a href="lwg-defects.html#189">189</a>. Issues list split into separate "active" and
"closed" documents. (99-0030/N1206, 25 Aug 99)
</li>
<li>R8: 
post-Dublin mailing. Updated to reflect LWG and full committee actions
in Dublin. (99-0016/N1193, 21 Apr 99)
</li>
<li>R7: 
pre-Dublin updated: Added issues <a href="lwg-active.html#130">130</a>, <a href="lwg-closed.html#131">131</a>,
<a href="lwg-defects.html#132">132</a>, <a href="lwg-defects.html#133">133</a>, <a href="lwg-defects.html#134">134</a>,
<a href="lwg-closed.html#135">135</a>, <a href="lwg-defects.html#136">136</a>, <a href="lwg-defects.html#137">137</a>,
<a href="lwg-closed.html#138">138</a>, <a href="lwg-defects.html#139">139</a> (31 Mar 99)
</li>
<li>R6: 
pre-Dublin mailing. Added issues <a href="lwg-defects.html#127">127</a>, <a href="lwg-closed.html#128">128</a>,
and <a href="lwg-defects.html#129">129</a>.  (99-0007/N1194, 22 Feb 99)
</li>
<li>R5: 
update issues <a href="lwg-defects.html#103">103</a>, <a href="lwg-defects.html#112">112</a>; added issues
<a href="lwg-defects.html#114">114</a> to <a href="lwg-defects.html#126">126</a>. Format revisions to prepare
for making list public. (30 Dec 98)
</li>
<li>R4: 
post-Santa Cruz II updated: Issues <a href="lwg-defects.html#110">110</a>,
<a href="lwg-closed.html#111">111</a>, <a href="lwg-defects.html#112">112</a>, <a href="lwg-closed.html#113">113</a> added, several
issues corrected. (22 Oct 98)
</li>
<li>R3: 
post-Santa Cruz II: Issues <a href="lwg-closed.html#94">94</a> to <a href="lwg-defects.html#109">109</a>
added, many issues updated to reflect LWG consensus (12 Oct 98)
</li>
<li>R2: 
pre-Santa Cruz II: Issues <a href="lwg-closed.html#73">73</a> to <a href="lwg-closed.html#93">93</a> added,
issue <a href="lwg-defects.html#17">17</a> updated. (29 Sep 98)
</li>
<li>R1: 
Correction to issue <a href="lwg-defects.html#55">55</a> resolution, <a href="lwg-defects.html#60">60</a> code
format, <a href="lwg-defects.html#64">64</a> title. (17 Sep 98)
</li>
</ul>
<h2>Closed Issues</h2>
<hr>
<a name="2"><h3>2.&nbsp;Auto_ptr conversions effects incorrect</h3></a><p><b>Section:</b>&nbsp;20.4.5.3 <a href="lib-utilities.html#lib.auto.ptr.conv"> [lib.auto.ptr.conv]</a>&nbsp; <b>Status:</b>&nbsp;<a href="lwg-active.html#NAD">NAD</a>&nbsp; <b>Submitter:</b>&nbsp;Nathan Myers&nbsp; <b>Date:</b>&nbsp;4 Dec 1997</p>
<p>Paragraph 1 in "Effects", says "Calls
p-&gt;release()" where it clearly must be "Calls
p.release()". (As it is, it seems to require using
auto_ptr&lt;&gt;::operator-&gt; to refer to X::release, assuming that
exists.)</p>
<p><b>Proposed resolution:</b></p>
<p>Change 20.4.5.3 <a href="lib-utilities.html#lib.auto.ptr.conv"> [lib.auto.ptr.conv]</a> paragraph 1 Effects from 
"Calls p-&gt;release()" to "Calls p.release()".</p>
<p><b>Rationale:</b></p>
<p>Not a defect: the proposed change is already found in the standard.
[Originally classified as a defect, later reclassified.]</p>
<hr>
<a name="4"><h3>4.&nbsp;Basic_string size_type and difference_type should be implementation defined</h3></a><p><b>Section:</b>&nbsp;21.3 <a href="lib-strings.html#lib.basic.string"> [lib.basic.string]</a>&nbsp; <b>Status:</b>&nbsp;<a href="lwg-active.html#NAD">NAD</a>&nbsp; <b>Submitter:</b>&nbsp;Beman Dawes&nbsp; <b>Date:</b>&nbsp;16 Nov 1997</p>
<p>In Morristown we changed the size_type and difference_type typedefs
for all the other containers to implementation defined with a
reference to 23.1 <a href="lib-containers.html#lib.container.requirements"> [lib.container.requirements]</a>.  This should probably also have been
done for strings. </p>
<p><b>Proposed resolution:</b></p>
<p><b>Rationale:</b></p>
<p>Not a defect.  [Originally classified as a defect, later
reclassified.]  basic_string, unlike the other standard library
template containers, is severely constrained by its use of
char_traits. Those types are dictated by the traits class, and are far
from implementation defined.</p>
<hr>
<a name="6"><h3>6.&nbsp;File position not an offset unimplementable</h3></a><p><b>Section:</b>&nbsp;27.4.3 <a href="lib-iostreams.html#lib.fpos"> [lib.fpos]</a>&nbsp; <b>Status:</b>&nbsp;<a href="lwg-active.html#NAD">NAD</a>&nbsp; <b>Submitter:</b>&nbsp;Matt Austern&nbsp; <b>Date:</b>&nbsp;15 Dec 1997</p>
<p>Table 88, in I/O, is too strict; it's unimplementable on systems
where a file position isn't just an offset. It also never says just
what fpos&lt;&gt; is really supposed to be.  [Here's my summary, which
Jerry agrees is more or less accurate. "I think I now know what
the class really is, at this point: it's a magic cookie that
encapsulates an mbstate_t and a file position (possibly represented as
an fpos_t), it has syntactic support for pointer-like arithmetic, and
implementors are required to have real, not just syntactic, support
for arithmetic." This isn't standardese, of course.] </p>
<p><b>Proposed resolution:</b></p>
<p><b>Rationale:</b></p>
<p>Not a defect. The LWG believes that the Standard is already clear,
and that the above summary is what the Standard in effect says.</p>
<hr>
<a name="10"><h3>10.&nbsp;Codecvt&lt;&gt;::do unclear</h3></a><p><b>Section:</b>&nbsp;22.2.1.5.2 <a href="lib-locales.html#lib.locale.codecvt.virtuals"> [lib.locale.codecvt.virtuals]</a>&nbsp; <b>Status:</b>&nbsp;<a href="lwg-active.html#Dup">Dup</a>&nbsp; <b>Submitter:</b>&nbsp;Matt Austern&nbsp; <b>Date:</b>&nbsp;14 Jan 1998</p>
<p>Section 22.2.1.5.2 says that codecvt&lt;&gt;::do_in and do_out
should return the value noconv if "no conversion was
needed". However, I don't see anything anywhere that defines what
it means for a conversion to be needed or not needed. I can think of
several circumstances where one might plausibly think that a
conversion is not "needed", but I don't know which one is
intended here. </p>
<p><b>Proposed resolution:</b></p>
<p><b>Rationale:</b></p>
<p>Duplicate. See issue <a href="lwg-defects.html#19">19</a>.</p>
<hr>
<a name="12"><h3>12.&nbsp;Way objects hold allocators unclear</h3></a><p><b>Section:</b>&nbsp;20.1.5 <a href="lib-utilities.html#lib.allocator.requirements"> [lib.allocator.requirements]</a>&nbsp; <b>Status:</b>&nbsp;<a href="lwg-active.html#NAD">NAD</a>&nbsp; <b>Submitter:</b>&nbsp;Angelika Langer&nbsp; <b>Date:</b>&nbsp;23 Feb 1998</p>
<p>I couldn't find a statement in the standard saying whether the allocator object held by
a container is held as a copy of the constructor argument or whether a pointer of
reference is maintained internal. There is an according statement for compare objects and
how they are maintained by the associative containers, but I couldn't find anything
regarding allocators. </p>

<p>Did I overlook it? Is it an open issue or known defect? Or is it deliberately left
unspecified? </p>
<p><b>Proposed resolution:</b></p>
<p><b>Rationale:</b></p>
<p>Not a defect. The LWG believes that the Standard is already
clear.&nbsp; See 23.1 <a href="lib-containers.html#lib.container.requirements"> [lib.container.requirements]</a>, paragraph 8.</p>
<hr>
<a name="43"><h3>43.&nbsp;Locale table correction</h3></a><p><b>Section:</b>&nbsp;22.2.1.5.2 <a href="lib-locales.html#lib.locale.codecvt.virtuals"> [lib.locale.codecvt.virtuals]</a>&nbsp; <b>Status:</b>&nbsp;<a href="lwg-active.html#Dup">Dup</a>&nbsp; <b>Submitter:</b>&nbsp;Brendan Kehoe&nbsp; <b>Date:</b>&nbsp;1 Jun 1998</p>
<p><b>Proposed resolution:</b></p>
<p><b>Rationale:</b></p>
<p>Duplicate. See issue <a href="lwg-defects.html#33">33</a>.</p>
<hr>
<a name="45"><h3>45.&nbsp;Stringstreams read/write pointers initial position unclear</h3></a><p><b>Section:</b>&nbsp;27.7.3 <a href="lib-iostreams.html#lib.ostringstream"> [lib.ostringstream]</a>&nbsp; <b>Status:</b>&nbsp;<a href="lwg-active.html#NAD">NAD</a>&nbsp; <b>Submitter:</b>&nbsp;Matthias Mueller&nbsp; <b>Date:</b>&nbsp;27 May 1998</p>
<p>In a comp.lang.c++.moderated Matthias Mueller wrote:</p>

<p>"We are not sure how to interpret the CD2 (see 27.2 <a href="lib-iostreams.html#lib.iostream.forward"> [lib.iostream.forward]</a>, 27.7.3.1 <a href="lib-iostreams.html#lib.ostringstream.cons"> [lib.ostringstream.cons]</a>, 27.7.1.1 <a href="lib-iostreams.html#lib.stringbuf.cons"> [lib.stringbuf.cons]</a>)
with respect to the question as to what the correct initial positions
of the write and&nbsp; read pointers of a stringstream should
be."</p>

<p>"Is it the same to output two strings or to initialize the stringstream with the
first and to output the second?"</p>

<p><i>[PJ Plauger, Bjarne Stroustrup, Randy Smithey, Sean Corfield, and
Jerry Schwarz have all offered opinions; see reflector messages
lib-6518, 6519, 6520, 6521, 6523, 6524.]</i></p>

<p><b>Proposed resolution:</b></p>
<p><b>Rationale:</b></p>
<p>The LWG believes the Standard is correct as written. The behavior
of stringstreams is consistent with fstreams, and there is a
constructor which can be used to obtain the desired effect. This
behavior is known to be different from strstreams.</p>
<hr>
<a name="58"><h3>58.&nbsp;Extracting a char from a wide-oriented stream</h3></a><p><b>Section:</b>&nbsp;27.6.1.2.3 <a href="lib-iostreams.html#lib.istream::extractors"> [lib.istream::extractors]</a>&nbsp; <b>Status:</b>&nbsp;<a href="lwg-active.html#NAD">NAD</a>&nbsp; <b>Submitter:</b>&nbsp;Matt Austern&nbsp; <b>Date:</b>&nbsp;1 Jul 1998</p>
<p>27.6.1.2.3 has member functions for extraction of signed char and
unsigned char, both singly and as strings. However, it doesn't say
what it means to extract a <tt>char</tt> from a
<tt>basic_streambuf&lt;charT, Traits&gt;</tt>. </p>

<p>basic_streambuf, after all, has no members to extract a char, so
basic_istream must somehow convert from charT to signed char or
unsigned char. The standard doesn't say how it is to perform that
conversion. </p>
<p><b>Proposed resolution:</b></p>
<p><b>Rationale:</b></p>
<p>The Standard is correct as written.  There is no such extractor and
this is the intent of the LWG.</p>
<hr>
<a name="65"><h3>65.&nbsp;Underspecification of strstreambuf::seekoff</h3></a><p><b>Section:</b>&nbsp;D.7.1.3 <a href="future.html#depr.strstreambuf.virtuals"> [depr.strstreambuf.virtuals]</a>&nbsp; <b>Status:</b>&nbsp;<a href="lwg-active.html#NAD">NAD</a>&nbsp; <b>Submitter:</b>&nbsp;Matt Austern&nbsp; <b>Date:</b>&nbsp;18 Aug 1998</p>
<p>The standard says how this member function affects the current
stream position. (<tt>gptr</tt> or <tt>pptr</tt>) However, it does not
say how this member function affects the beginning and end of the
get/put area. </p>

<p>This is an issue when seekoff is used to position the get pointer
beyond the end of the current read area. (Which is legal. This is
implicit in the definition of <i>seekhigh</i> in D.7.1, paragraph 4.)
</p>
<p><b>Proposed resolution:</b></p>
<p><b>Rationale:</b></p>
<p>The LWG agrees that seekoff() is underspecified, but does not wish
to invest effort in this deprecated feature.</p>
<hr>
<a name="67"><h3>67.&nbsp;Setw useless for strings</h3></a><p><b>Section:</b>&nbsp;21.3.7.9 <a href="lib-strings.html#lib.string.io"> [lib.string.io]</a>&nbsp; <b>Status:</b>&nbsp;<a href="lwg-active.html#Dup">Dup</a>&nbsp; <b>Submitter:</b>&nbsp;Steve Clamage&nbsp; <b>Date:</b>&nbsp;9 Jul 1998</p>
<p>In a comp.std.c++ posting Michel Michaud wrote: What
should be output by: </p>

<pre>   string text("Hello");
   cout &lt;&lt; '[' &lt;&lt; setw(10) &lt;&lt; right &lt;&lt; text &lt;&lt; ']';
</pre>

<p>Shouldn't it be:</p>

<pre>   [     Hello]</pre>

<p>Another person replied: Actually, according to the FDIS, the width
of the field should be the minimum of width and the length of the
string, so the output shouldn't have any padding. I think that this is
a typo, however, and that what is wanted is the maximum of the
two. (As written, setw is useless for strings. If that had been the
intent, one wouldn't expect them to have mentioned using its value.)
</p>

<p>It's worth pointing out that this is a recent correction anyway;
IIRC, earlier versions of the draft forgot to mention formatting
parameters whatsoever.</p>
<p><b>Proposed resolution:</b></p>
<p><b>Rationale:</b></p>
<p>Duplicate. See issue <a href="lwg-defects.html#25">25</a>.</p>
<hr>
<a name="72"><h3>72.&nbsp;Do_convert phantom member function</h3></a><p><b>Section:</b>&nbsp;22.2.1.5 <a href="lib-locales.html#lib.locale.codecvt"> [lib.locale.codecvt]</a>&nbsp; <b>Status:</b>&nbsp;<a href="lwg-active.html#Dup">Dup</a>&nbsp; <b>Submitter:</b>&nbsp;Nathan Myers&nbsp; <b>Date:</b>&nbsp;24 Aug 1998</p>
<p>In 22.2.1.5 <a href="lib-locales.html#lib.locale.codecvt"> [lib.locale.codecvt]</a> par 3, and in 22.2.1.5.2 <a href="lib-locales.html#lib.locale.codecvt.virtuals"> [lib.locale.codecvt.virtuals]</a> par 8, a nonexistent member function
"do_convert" is mentioned. This member was replaced with
"do_in" and "do_out", the proper referents in the
contexts above.</p>
<p><b>Proposed resolution:</b></p>
<p><b>Rationale:</b></p>
<p>Duplicate: see issue <a href="lwg-defects.html#24">24</a>.</p>
<hr>
<a name="73"><h3>73.&nbsp;<tt>is_open</tt> should be const</h3></a><p><b>Section:</b>&nbsp;27.8.1 <a href="lib-iostreams.html#lib.fstreams"> [lib.fstreams]</a>&nbsp; <b>Status:</b>&nbsp;<a href="lwg-active.html#NAD">NAD</a>&nbsp; <b>Submitter:</b>&nbsp;Matt Austern&nbsp; <b>Date:</b>&nbsp;27 Aug 1998</p>
<p>Classes <tt>basic_ifstream</tt>, <tt>basic_ofstream</tt>, and
<tt>basic_fstream</tt> all have a member function <tt>is_open</tt>. It
should be a <tt>const</tt> member function, since it does nothing but
call one of <tt>basic_filebuf</tt>'s const member functions. </p>
<p><b>Proposed resolution:</b></p>
<p><b>Rationale:</b></p>
<p>Not a defect. This is a deliberate feature; const streams would be
meaningless.</p>
<hr>
<a name="77"><h3>77.&nbsp;Valarray operator[] const returning value</h3></a><p><b>Section:</b>&nbsp;26.3.2.3 <a href="lib-numerics.html#lib.valarray.access"> [lib.valarray.access]</a>&nbsp; <b>Status:</b>&nbsp;<a href="lwg-active.html#NAD">NAD</a>&nbsp;<a href="lwg-active.html#Future">Future</a>&nbsp; <b>Submitter:</b>&nbsp;Levente Farkas&nbsp; <b>Date:</b>&nbsp;9 Sep 1998</p>
<p>valarray:<br>
<br>
&nbsp;&nbsp;&nbsp; <tt>T operator[] (size_t) const;</tt><br>
<br>
why not <br>
<br>
&nbsp;&nbsp;&nbsp; <tt>const T&amp; operator[] (size_t) const;</tt><br>
<br>
as in vector ???<br>
<br>
One can't copy even from a const valarray eg:<br>
<br>
&nbsp;&nbsp;&nbsp; <tt>memcpy(ptr, &amp;v[0], v.size() * sizeof(double));<br>
</tt><br>
[I] find this bug in valarray is very difficult.</p>
<p><b>Proposed resolution:</b></p>
<p><b>Rationale:</b></p>
<p>The LWG believes that the interface was deliberately designed that
way. That is what valarray was designed to do; that's where the
"value array" name comes from. LWG members further comment
that "we don't want valarray to be a full STL container."
26.3.2.3 <a href="lib-numerics.html#lib.valarray.access"> [lib.valarray.access]</a> specifies properties that indicate "an
absence of aliasing" for non-constant arrays; this allows
optimizations, including special hardware optimizations, that are not
otherwise possible. </p>
<hr>
<a name="81"><h3>81.&nbsp;Wrong declaration of slice operations</h3></a><p><b>Section:</b>&nbsp;26.3.5 <a href="lib-numerics.html#lib.template.slice.array"> [lib.template.slice.array]</a>, 26.3.7 <a href="lib-numerics.html#lib.template.gslice.array"> [lib.template.gslice.array]</a>, 26.3.8 <a href="lib-numerics.html#lib.template.mask.array"> [lib.template.mask.array]</a>, 26.3.9 <a href="lib-numerics.html#lib.template.indirect.array"> [lib.template.indirect.array]</a>&nbsp; <b>Status:</b>&nbsp;<a href="lwg-active.html#NAD">NAD</a>&nbsp; <b>Submitter:</b>&nbsp;Nico Josuttis&nbsp; <b>Date:</b>&nbsp;29 Sep 1998</p>
<p>Isn't the definition of copy constructor and assignment operators wrong?
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; Instead of</p>

<pre>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; slice_array(const slice_array&amp;); 
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; slice_array&amp; operator=(const slice_array&amp;);</pre>

<p>IMHO they have to be</p>

<pre>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;slice_array(const slice_array&lt;T&gt;&amp;); 
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;slice_array&amp; operator=(const slice_array&lt;T&gt;&amp;);</pre>

<p>Same for gslice_array. </p>
<p><b>Proposed resolution:</b></p>
<p><b>Rationale:</b></p>
<p>Not a defect. The Standard is correct as written. </p>
<hr>
<a name="82"><h3>82.&nbsp;Missing constant for set elements</h3></a><p><b>Section:</b>&nbsp;23.1.2 <a href="lib-containers.html#lib.associative.reqmts"> [lib.associative.reqmts]</a>&nbsp; <b>Status:</b>&nbsp;<a href="lwg-active.html#NAD">NAD</a>&nbsp; <b>Submitter:</b>&nbsp;Nico Josuttis&nbsp; <b>Date:</b>&nbsp;29 Sep 1998</p>
<p>Paragraph 5 specifies:</p>

<blockquote>
For set and multiset the value type is the same as the key type. For
map and multimap it is equal to pair&lt;const Key, T&gt;.  
</blockquote>

<p>Strictly speaking, this is not correct because for set and multiset
the value type is the same as the <b>constant</b> key type.</p>
<p><b>Proposed resolution:</b></p>
<p><b>Rationale:</b></p>
<p>Not a defect. The Standard is correct as written; it uses a
different mechanism (const &amp;) for <tt>set</tt> and
<tt>multiset</tt>. See issue <a href="lwg-defects.html#103">103</a> for a related
issue.</p>
<hr>
<a name="84"><h3>84.&nbsp;Ambiguity with string::insert()</h3></a><p><b>Section:</b>&nbsp;21.3.5 <a href="lib-strings.html#lib.string.modifiers"> [lib.string.modifiers]</a>&nbsp; <b>Status:</b>&nbsp;<a href="lwg-active.html#NAD">NAD</a>&nbsp; <b>Submitter:</b>&nbsp;Nico Josuttis&nbsp; <b>Date:</b>&nbsp;29 Sep 1998</p>
<p>If I try</p>
<pre>    s.insert(0,1,' ');</pre>

<p>&nbsp; I get an nasty ambiguity. It might be</p>
<pre>    s.insert((size_type)0,(size_type)1,(charT)' ');</pre>

<p>which inserts 1 space character at position 0, or</p>
<pre>    s.insert((char*)0,(size_type)1,(charT)' ')</pre>

<p>which inserts 1 space character at iterator/address 0 (bingo!), or</p>
<pre>    s.insert((char*)0, (InputIterator)1, (InputIterator)' ')</pre>

<p>which normally inserts characters from iterator 1 to iterator '
'. But according to 23.1.1.9 (the "do the right thing" fix)
it is equivalent to the second. However, it is still ambiguous,
because of course I mean the first!</p>
<p><b>Proposed resolution:</b></p>
<p><b>Rationale:</b></p>
<p>Not a defect. The LWG believes this is a "genetic
misfortune" inherent in the design of string and thus not a
defect in the Standard as such .</p>
<hr>
<a name="85"><h3>85.&nbsp;String char types</h3></a><p><b>Section:</b>&nbsp;21 <a href="lib-strings.html#lib.strings"> [lib.strings]</a>&nbsp; <b>Status:</b>&nbsp;<a href="lwg-active.html#NAD">NAD</a>&nbsp; <b>Submitter:</b>&nbsp;Nico Josuttis&nbsp; <b>Date:</b>&nbsp;29 Sep 1998</p>
<p>The standard seems not to require that charT is equivalent to
traits::char_type. So, what happens if charT is not equivalent to
traits::char_type?</p>
<p><b>Proposed resolution:</b></p>
<p><b>Rationale:</b></p>
<p>There is already wording in 21.1 <a href="lib-strings.html#lib.char.traits"> [lib.char.traits]</a> paragraph 3 that
requires them to be the same.</p>
<hr>
<a name="87"><h3>87.&nbsp;Error in description of string::compare()</h3></a><p><b>Section:</b>&nbsp;21.3.6.8 <a href="lib-strings.html#lib.string::compare"> [lib.string::compare]</a>&nbsp; <b>Status:</b>&nbsp;<a href="lwg-active.html#Dup">Dup</a>&nbsp; <b>Submitter:</b>&nbsp;Nico Josuttis&nbsp; <b>Date:</b>&nbsp;29 Sep 1998</p>
<p>The following compare() description is obviously a bug:</p>

<pre>
int compare(size_type pos, size_type n1, 
            charT *s, size_type n2 = npos) const;
</pre>

<p>because without passing n2 it should compare up to the end of the
string instead of comparing npos characters (which throws an
exception) </p>
<p><b>Proposed resolution:</b></p>
<p><b>Rationale:</b></p>
<p>Duplicate; see issue <a href="lwg-defects.html#5">5</a>.</p>
<hr>
<a name="88"><h3>88.&nbsp;Inconsistency between string::insert() and string::append()</h3></a><p><b>Section:</b>&nbsp;21.3.5.4 <a href="lib-strings.html#lib.string::insert"> [lib.string::insert]</a>, 21.3.5.2 <a href="lib-strings.html#lib.string::append"> [lib.string::append]</a>&nbsp; <b>Status:</b>&nbsp;<a href="lwg-active.html#NAD">NAD</a>&nbsp; <b>Submitter:</b>&nbsp;Nico Josuttis&nbsp; <b>Date:</b>&nbsp;29 Sep 1998</p>
<p>Why does </p>
<pre>  template&lt;class InputIterator&gt; 
       basic_string&amp; append(InputIterator first, InputIterator last);</pre>

<p>return a string, while</p>
<pre>  template&lt;class InputIterator&gt; 
       void insert(iterator p, InputIterator first, InputIterator last);</pre>

<p>returns nothing ?</p>
<p><b>Proposed resolution:</b></p>
<p><b>Rationale:</b></p>
<p>The LWG believes this stylistic inconsistency is not sufficiently 
serious to constitute a defect.</p>
<hr>
<a name="89"><h3>89.&nbsp;Missing throw specification for string::insert() and string::replace()</h3></a><p><b>Section:</b>&nbsp;21.3.5.4 <a href="lib-strings.html#lib.string::insert"> [lib.string::insert]</a>, 21.3.5.6 <a href="lib-strings.html#lib.string::replace"> [lib.string::replace]</a>&nbsp; <b>Status:</b>&nbsp;<a href="lwg-active.html#Dup">Dup</a>&nbsp; <b>Submitter:</b>&nbsp;Nico Josuttis&nbsp; <b>Date:</b>&nbsp;29 Sep 1998</p>
<p>All insert() and replace() members for strings with an iterator as
first argument lack a throw specification. The throw
specification should probably be: length_error if size exceeds
maximum. </p>
<p><b>Proposed resolution:</b></p>
<p><b>Rationale:</b></p>
<p>Considered a duplicate because it will be solved by the resolution
of issue <a href="lwg-defects.html#83">83</a>.</p>
<hr>
<a name="93"><h3>93.&nbsp;Incomplete Valarray Subset Definitions</h3></a><p><b>Section:</b>&nbsp;26.3 <a href="lib-numerics.html#lib.numarray"> [lib.numarray]</a>&nbsp; <b>Status:</b>&nbsp;<a href="lwg-active.html#NAD">NAD</a>&nbsp; <b>Submitter:</b>&nbsp;Nico Josuttis&nbsp; <b>Date:</b>&nbsp;29 Sep 1998</p>
<p>You can easily create subsets, but you can't easily combine them
with other subsets.  Unfortunately, you almost always needs an
explicit type conversion to valarray. This is because the standard
does not specify that valarray subsets provide the same operations as
valarrays. </p>

<p>For example, to multiply two subsets and assign the result to a third subset, you can't
write the following:</p>

<pre>va[slice(0,4,3)] = va[slice(1,4,3)] * va[slice(2,4,3)];</pre>

<p>Instead, you have to code as follows:</p>

<pre>va[slice(0,4,3)] = static_cast&lt;valarray&lt;double&gt; &gt;(va[slice(1,4,3)]) * 
                   static_cast&lt;valarray&lt;double&gt; &gt;(va[slice(2,4,3)]);</pre>

<p>This is tedious and error-prone. Even worse, it costs performance because each cast
creates a temporary objects, which could be avoided without the cast. </p>
<p><b>Proposed resolution:</b></p>
<p>Extend all valarray subset types so that they offer all valarray operations.</p>
<p><b>Rationale:</b></p>
<p>This is not a defect in the Standard; it is a request for an extension.</p>
<hr>
<a name="94"><h3>94.&nbsp;May library implementors add template parameters to Standard Library classes?</h3></a><p><b>Section:</b>&nbsp;17.4.4 <a href="lib-intro.html#lib.conforming"> [lib.conforming]</a>&nbsp; <b>Status:</b>&nbsp;<a href="lwg-active.html#NAD">NAD</a>&nbsp; <b>Submitter:</b>&nbsp;Matt Austern&nbsp; <b>Date:</b>&nbsp;22 Jan 1998</p>
<p>Is it a permitted extension for library implementors to add template parameters to
standard library classes, provided that those extra parameters have defaults? For example,
instead of defining <tt>template &lt;class T, class Alloc = allocator&lt;T&gt; &gt; class
vector;</tt> defining it as <tt>template &lt;class T, class Alloc = allocator&lt;T&gt;,
int N = 1&gt; class vector;</tt> </p>

<p>The standard may well already allow this (I can't think of any way that this extension
could break a conforming program, considering that users are not permitted to
forward-declare standard library components), but it ought to be explicitly permitted or
forbidden. </p>

<p>comment from Steve Cleary via comp.std.c++:</p>
<blockquote>
<p>I disagree [with the proposed resolution] for the following reason:
consider user library code with template template parameters. For
example, a user library object may be templated on the type of
underlying sequence storage to use (deque/list/vector), since these
classes all take the same number and type of template parameters; this
would allow the user to determine the performance tradeoffs of the
user library object. A similar example is a user library object
templated on the type of underlying set storage (set/multiset) or map
storage (map/multimap), which would allow users to change (within
reason) the semantic meanings of operations on that object.</p>
<p>I think that additional template parameters should be forbidden in
the Standard classes. Library writers don't lose any expressive power,
and can still offer extensions because additional template parameters
may be provided by a non-Standard implementation class:</p>
<pre> 
   template &lt;class T, class Allocator = allocator&lt;T&gt;, int N = 1&gt;
   class __vector
   { ... };
   template &lt;class T, class Allocator = allocator&lt;T&gt; &gt;
   class vector: public __vector&lt;T, Allocator&gt;
   { ... };
</pre>

</blockquote>

<p><b>Proposed resolution:</b></p>
<p>Add a new subclause [presumably 17.4.4.9] following 17.4.4.8 <a href="lib-intro.html#lib.res.on.exception.handling"> [lib.res.on.exception.handling]</a>:</p>

<blockquote>
  <p>17.4.4.9 Template Parameters</p> <p>A specialization of a
  template class described in the C++ Standard Library behaves the
  same as if the implementation declares no additional template
  parameters.</p> <p>Footnote: Additional template parameters with
  default values are thus permitted.</p>
</blockquote>

<p>Add "template parameters" to the list of subclauses at
the end of 17.4.4 <a href="lib-intro.html#lib.conforming"> [lib.conforming]</a> paragraph 1.</p>

<p><i>[Kona: The LWG agreed the standard needs clarification. After
discussion with John Spicer, it seems added template parameters can be
detected by a program using template-template parameters. A straw vote
- "should implementors be allowed to add template
parameters?" found no consensus ; 5 - yes, 7 - no.]</i></p>

<p><b>Rationale:</b></p>
<p>
There is no ambiguity; the standard is clear as written.  Library
implementors are not permitted to add template parameters to standard
library classes.  This does not fall under the "as if" rule,
so it would be permitted only if the standard gave explicit license
for implementors to do this.  This would require a change in the 
standard.
</p>

<p>
The LWG decided against making this change, because it would break
user code involving template template parameters or specializations
of standard library class templates.
</p>
<hr>
<a name="95"><h3>95.&nbsp;Members added by the implementation</h3></a><p><b>Section:</b>&nbsp;17.4.4.4 <a href="lib-intro.html#lib.member.functions"> [lib.member.functions]</a>&nbsp; <b>Status:</b>&nbsp;<a href="lwg-active.html#NAD">NAD</a>&nbsp; <b>Submitter:</b>&nbsp;AFNOR&nbsp; <b>Date:</b>&nbsp;7 Oct 1998</p>
<p>In 17.3.4.4/2 vs 17.3.4.7/0 there is a hole; an implementation could add virtual
members a base class and break user derived classes.</p>

<p>Example: </p>

<blockquote>
  <pre>// implementation code:
struct _Base { // _Base is in the implementer namespace
        virtual void foo ();
};
class vector : _Base // deriving from a class is allowed
{ ... };

// user code:
class vector_checking : public vector 
{
        void foo (); // don't want to override _Base::foo () as the 
                     // user doesn't know about _Base::foo ()
};</pre>
</blockquote>
<p><b>Proposed resolution:</b></p>
<p>Clarify the wording to make the example illegal.</p>
<p><b>Rationale:</b></p>
<p>This is not a defect in the Standard.&nbsp; The example is already
illegal.&nbsp; See 17.4.4.4 <a href="lib-intro.html#lib.member.functions"> [lib.member.functions]</a> paragraph 2.</p>
<hr>
<a name="97"><h3>97.&nbsp;Insert inconsistent definition</h3></a><p><b>Section:</b>&nbsp;23 <a href="lib-containers.html#lib.containers"> [lib.containers]</a>&nbsp; <b>Status:</b>&nbsp;<a href="lwg-active.html#NAD">NAD</a>&nbsp; <b>Submitter:</b>&nbsp;AFNOR&nbsp; <b>Date:</b>&nbsp;7 Oct 1998</p>
<p><tt>insert(iterator, const value_type&amp;)</tt> is defined both on
sequences and on set, with unrelated semantics: insert here (in
sequences), and insert with hint (in associative containers). They
should have different names (B.S. says: do not abuse overloading).</p>
<p><b>Proposed resolution:</b></p>
<p><b>Rationale:</b></p>
<p>This is not a defect in the Standard. It is a genetic misfortune of
the design, for better or for worse.</p>
<hr>
<a name="99"><h3>99.&nbsp;Reverse_iterator comparisons completely wrong</h3></a><p><b>Section:</b>&nbsp;24.4.1.3.13 <a href="lib-iterators.html#lib.reverse.iter.op&lt;"> [lib.reverse.iter.op&lt;]</a>&nbsp; <b>Status:</b>&nbsp;<a href="lwg-active.html#NAD">NAD</a>&nbsp; <b>Submitter:</b>&nbsp;AFNOR&nbsp; <b>Date:</b>&nbsp;7 Oct 1998</p>
<p>The &lt;, &gt;, &lt;=, &gt;= comparison operator are wrong: they
return the opposite of what they should.</p>

<p>Note: same problem in CD2, these were not even defined in CD1.  SGI
STL code is correct; this problem is known since the Morristown
meeting but there it was too late</p>
<p><b>Proposed resolution:</b></p>
<p><b>Rationale:</b></p>
<p>This is not a defect in the Standard. A careful reading shows the Standard is correct
as written. A review of several implementations show that they implement
exactly what the Standard says.</p>
<hr>
<a name="100"><h3>100.&nbsp;Insert iterators/ostream_iterators overconstrained</h3></a><p><b>Section:</b>&nbsp;24.4.2 <a href="lib-iterators.html#lib.insert.iterators"> [lib.insert.iterators]</a>, 24.5.4 <a href="lib-iterators.html#lib.ostreambuf.iterator"> [lib.ostreambuf.iterator]</a>&nbsp; <b>Status:</b>&nbsp;<a href="lwg-active.html#NAD">NAD</a>&nbsp; <b>Submitter:</b>&nbsp;AFNOR&nbsp; <b>Date:</b>&nbsp;7 Oct 1998</p>
<p>Overspecified For an insert iterator it, the expression *it is
required to return a reference to it. This is a simple possible
implementation, but as the SGI STL documentation says, not the only
one, and the user should not assume that this is the case.</p>
<p><b>Proposed resolution:</b></p>
<p><b>Rationale:</b></p>
<p>The LWG believes this causes no harm and is not a defect in the
standard. The only example anyone could come up with caused some
incorrect code to work, rather than the other way around.</p>
<hr>
<a name="101"><h3>101.&nbsp;No way to free storage for vector and deque</h3></a><p><b>Section:</b>&nbsp;23.2.4 <a href="lib-containers.html#lib.vector"> [lib.vector]</a>, 23.2.1 <a href="lib-containers.html#lib.deque"> [lib.deque]</a>&nbsp; <b>Status:</b>&nbsp;<a href="lwg-active.html#NAD">NAD</a>&nbsp; <b>Submitter:</b>&nbsp;AFNOR&nbsp; <b>Date:</b>&nbsp;7 Oct 1998</p>
<p>Reserve can not free storage, unlike string::reserve</p>
<p><b>Proposed resolution:</b></p>
<p><b>Rationale:</b></p>
<p>This is not a defect in the Standard. The LWG has considered this
issue in the past and sees no need to change the Standard. Deque has
no reserve() member function. For vector, shrink-to-fit can be
expressed in a single line of code (where <tt>v</tt> is
<tt>vector&lt;T&gt;</tt>):
</p>

<blockquote>
  <p><tt>vector&lt;T&gt;(v).swap(v);&nbsp; // shrink-to-fit v</tt></p>
</blockquote>
<hr>
<a name="102"><h3>102.&nbsp;Bug in insert range in associative containers</h3></a><p><b>Section:</b>&nbsp;23.1.2 <a href="lib-containers.html#lib.associative.reqmts"> [lib.associative.reqmts]</a>&nbsp; <b>Status:</b>&nbsp;<a href="lwg-active.html#Dup">Dup</a>&nbsp; <b>Submitter:</b>&nbsp;AFNOR&nbsp; <b>Date:</b>&nbsp;7 Oct 1998</p>
<p>Table 69 of Containers say that a.insert(i,j) is linear if [i, j) is ordered. It seems
impossible to implement, as it means that if [i, j) = [x], insert in an associative
container is O(1)!</p>
<p><b>Proposed resolution:</b></p>
<p>N+log (size()) if [i,j) is sorted according to value_comp()</p>
<p><b>Rationale:</b></p>
<p>Subsumed by issue <a href="lwg-defects.html#264">264</a>.</p>
<hr>
<a name="104"><h3>104.&nbsp;Description of basic_string::operator[] is unclear</h3></a><p><b>Section:</b>&nbsp;21.3.4 <a href="lib-strings.html#lib.string.access"> [lib.string.access]</a>&nbsp; <b>Status:</b>&nbsp;<a href="lwg-active.html#NAD">NAD</a>&nbsp; <b>Submitter:</b>&nbsp;AFNOR&nbsp; <b>Date:</b>&nbsp;7 Oct 1998</p>
<p>It is not clear that undefined behavior applies when pos == size ()
for the non const version.</p>
<p><b>Proposed resolution:</b></p>
<p>Rewrite as: Otherwise, if pos &gt; size () or pos == size () and
the non-const version is used, then the behavior is undefined.</p>
<p><b>Rationale:</b></p>
<p>The Standard is correct. The proposed resolution already appears in
the Standard.</p>
<hr>
<a name="105"><h3>105.&nbsp;fstream ctors argument types desired</h3></a><p><b>Section:</b>&nbsp;27.8 <a href="lib-iostreams.html#lib.file.streams"> [lib.file.streams]</a>&nbsp; <b>Status:</b>&nbsp;<a href="lwg-active.html#NAD">NAD</a>&nbsp;<a href="lwg-active.html#Future">Future</a>&nbsp; <b>Submitter:</b>&nbsp;AFNOR&nbsp; <b>Date:</b>&nbsp;7 Oct 1998</p>
<p>fstream ctors take a const char* instead of string.<br>
fstream ctors can't take wchar_t</p>

<p>An extension to add a const wchar_t* to fstream would make the
implementation non conforming.</p>
<p><b>Proposed resolution:</b></p>
<p><b>Rationale:</b></p>
<p>This is not a defect in the Standard. It might be an
interesting extension for the next Standard. </p>
<hr>
<a name="107"><h3>107.&nbsp;Valarray constructor is strange</h3></a><p><b>Section:</b>&nbsp;26.3.2 <a href="lib-numerics.html#lib.template.valarray"> [lib.template.valarray]</a>&nbsp; <b>Status:</b>&nbsp;<a href="lwg-active.html#NAD">NAD</a>&nbsp; <b>Submitter:</b>&nbsp;AFNOR&nbsp; <b>Date:</b>&nbsp;7 Oct 1998</p>
<p>The order of the arguments is (elem, size) instead of the normal
(size, elem) in the rest of the library. Since elem often has an
integral or floating point type, both types are convertible to each
other and reversing them leads to a well formed program.</p>
<p><b>Proposed resolution:</b></p>
<p>Inverting the arguments could silently break programs. Introduce
the two signatures (const T&amp;, size_t) and (size_t, const T&amp;),
but make the one we do not want private so errors result in a
diagnosed access violation. This technique can also be applied to STL
containers.</p>
<p><b>Rationale:</b></p>
<p>The LWG believes that while the order of arguments is unfortunate,
it does not constitute a defect in the standard. The LWG believes that
the proposed solution will not work for valarray&lt;size_t&gt; and
perhaps other cases.</p>
<hr>
<a name="111"><h3>111.&nbsp;istreambuf_iterator::equal overspecified, inefficient</h3></a><p><b>Section:</b>&nbsp;24.5.3.5 <a href="lib-iterators.html#lib.istreambuf.iterator::equal"> [lib.istreambuf.iterator::equal]</a>&nbsp; <b>Status:</b>&nbsp;<a href="lwg-active.html#NAD">NAD</a>&nbsp;<a href="lwg-active.html#Future">Future</a>&nbsp; <b>Submitter:</b>&nbsp;Nathan Myers&nbsp; <b>Date:</b>&nbsp;15 Oct 1998</p>
<p>The member istreambuf_iterator&lt;&gt;::equal is specified to be
unnecessarily inefficient. While this does not affect the efficiency
of conforming implementations of iostreams, because they can
"reach into" the iterators and bypass this function, it does
affect users who use istreambuf_iterators. </p>

<p>The inefficiency results from a too-scrupulous definition, which
requires a "true" result if neither iterator is at eof. In
practice these iterators can only usefully be compared with the
"eof" value, so the extra test implied provides no benefit,
but slows down users' code. </p>

<p>The solution is to weaken the requirement on the function to return
true only if both iterators are at eof. </p>
<p><b>Proposed resolution:</b></p>
<p>Replace 24.5.3.5 <a href="lib-iterators.html#lib.istreambuf.iterator::equal"> [lib.istreambuf.iterator::equal]</a>,
paragraph 1, </p>

<blockquote>
  <p>-1- Returns: true if and only if both iterators are at end-of-stream, or neither is at
  end-of-stream, regardless of what streambuf object they use. </p>
</blockquote>

<p>with</p>

<blockquote>
  <p>-1- Returns: true if and only if both iterators are at
  end-of-stream, regardless of what streambuf object they use. </p>
</blockquote>

<p><b>Rationale:</b></p>
<p>It is not clear that this is a genuine defect.  Additionally, the
LWG was reluctant to make a change that would result in 
operator== not being a equivalence relation.  One consequence of
this change is that an algorithm that's passed the range [i, i)
would no longer treat it as an empty range.</p>
<hr>
<a name="113"><h3>113.&nbsp;Missing/extra iostream sync semantics</h3></a><p><b>Section:</b>&nbsp;27.6.1.1 <a href="lib-iostreams.html#lib.istream"> [lib.istream]</a>, 27.6.1.3 <a href="lib-iostreams.html#lib.istream.unformatted"> [lib.istream.unformatted]</a>&nbsp; <b>Status:</b>&nbsp;<a href="lwg-active.html#NAD">NAD</a>&nbsp; <b>Submitter:</b>&nbsp;Steve Clamage&nbsp; <b>Date:</b>&nbsp;13 Oct 1998</p>
<p>In 27.6.1.1, class basic_istream has a member function sync, described in 27.6.1.3,
paragraph 36. </p>

<p>Following the chain of definitions, I find that the various sync functions have defined
semantics for output streams, but no semantics for input streams. On the other hand,
basic_ostream has no sync function. </p>

<p>The sync function should at minimum be added to basic_ostream, for internal
consistency. </p>

<p>A larger question is whether sync should have assigned semantics for input streams. </p>

<p>Classic iostreams said streambuf::sync flushes pending output and attempts to return
unread input characters to the source. It is a protected member function. The filebuf
version (which is public) has that behavior (it backs up the read pointer). Class
strstreambuf does not override streambuf::sync, and so sync can't be called on a
strstream. </p>

<p>If we can add corresponding semantics to the various sync functions, we should. If not,
we should remove sync from basic_istream.</p>
<p><b>Proposed resolution:</b></p>
<p><b>Rationale:</b></p>
<p>A sync function is not needed in basic_ostream because the flush function provides the
desired functionality.</p>

<p>As for the other points, the LWG finds the standard correct as written.</p>
<hr>
<a name="116"><h3>116.&nbsp;bitset cannot be constructed with a const char*</h3></a><p><b>Section:</b>&nbsp;23.3.5 <a href="lib-containers.html#lib.template.bitset"> [lib.template.bitset]</a>&nbsp; <b>Status:</b>&nbsp;<a href="lwg-active.html#NAD">NAD</a>&nbsp;<a href="lwg-active.html#Future">Future</a>&nbsp; <b>Submitter:</b>&nbsp;Judy Ward&nbsp; <b>Date:</b>&nbsp;6 Nov 1998</p>
<p>The following code does not compile with the EDG compiler:</p>

<blockquote>
  <pre>#include &lt;bitset&gt;
using namespace std;
bitset&lt;32&gt; b("111111111");</pre>
</blockquote>

<p>If you cast the ctor argument to a string, i.e.:</p>

<blockquote>
  <pre>bitset&lt;32&gt; b(string("111111111"));</pre>
</blockquote>

<p>then it will compile. The reason is that bitset has the following templatized
constructor:</p>

<blockquote>
  <pre>template &lt;class charT, class traits, class Allocator&gt;
explicit bitset (const basic_string&lt;charT, traits, Allocator&gt;&amp; str, ...);</pre>
</blockquote>

<p>According to the compiler vendor, Steve Adamcyk at EDG, the user
cannot pass this template constructor a <tt>const char*</tt> and
expect a conversion to <tt>basic_string</tt>.  The reason is
"When you have a template constructor, it can get used in
contexts where type deduction can be done. Type deduction basically
comes up with exact matches, not ones involving conversions."
</p>

<p>I don't think the intention when this constructor became
templatized was for construction from a <tt>const char*</tt> to no
longer work.</p>
<p><b>Proposed resolution:</b></p>
<p>Add to 23.3.5 <a href="lib-containers.html#lib.template.bitset"> [lib.template.bitset]</a> a bitset constructor declaration</p>

<blockquote>
  <pre>explicit bitset(const char*);</pre>
</blockquote>

<p>and in Section 23.3.5.1 <a href="lib-containers.html#lib.bitset.cons"> [lib.bitset.cons]</a> add:</p>

<blockquote>
  <pre>explicit bitset(const char* str);</pre>
  <p>Effects: <br>
  &nbsp;&nbsp;&nbsp; Calls <tt>bitset((string) str, 0, string::npos);</tt></p>
</blockquote>
<p><b>Rationale:</b></p>
<p>Although the problem is real, the standard is designed that way so
it is not a defect.  Education is the immediate workaround. A future
standard may wish to consider the Proposed Resolution as an
extension.</p>
<hr>
<a name="121"><h3>121.&nbsp;Detailed definition for ctype&lt;wchar_t&gt; specialization</h3></a><p><b>Section:</b>&nbsp;22.1.1.1.1 <a href="lib-locales.html#lib.locale.category"> [lib.locale.category]</a>&nbsp; <b>Status:</b>&nbsp;<a href="lwg-active.html#NAD">NAD</a>&nbsp; <b>Submitter:</b>&nbsp;Judy Ward&nbsp; <b>Date:</b>&nbsp;15 Dec 1998</p>
<p>Section 22.1.1.1.1 has the following listed in Table 51: ctype&lt;char&gt; ,
ctype&lt;wchar_t&gt;. </p>

<p>Also Section 22.2.1.1 <a href="lib-locales.html#lib.locale.ctype"> [lib.locale.ctype]</a> says: </p>

<blockquote>
  <p>The instantiations required in Table 51 (22.1.1.1.1) namely ctype&lt;char&gt; and
  ctype&lt;wchar_t&gt; , implement character classing appropriate to the implementation's
  native character set. </p>
</blockquote>

<p>However, Section 22.2.1.3 <a href="lib-locales.html#lib.facet.ctype.special"> [lib.facet.ctype.special]</a>
only has a detailed description of the ctype&lt;char&gt; specialization, not the
ctype&lt;wchar_t&gt; specialization. </p>
<p><b>Proposed resolution:</b></p>
<p>Add the ctype&lt;wchar_t&gt; detailed class description to Section 
22.2.1.3 <a href="lib-locales.html#lib.facet.ctype.special"> [lib.facet.ctype.special]</a>. </p>
<p><b>Rationale:</b></p>
<p>Specialization for wchar_t is not needed since the default is acceptable.</p>
<hr>
<a name="128"><h3>128.&nbsp;Need open_mode() function for file stream, string streams, file buffers, and string&nbsp; buffers</h3></a><p><b>Section:</b>&nbsp;27.7 <a href="lib-iostreams.html#lib.string.streams"> [lib.string.streams]</a>, 27.8 <a href="lib-iostreams.html#lib.file.streams"> [lib.file.streams]</a>&nbsp; <b>Status:</b>&nbsp;<a href="lwg-active.html#NAD">NAD</a>&nbsp;<a href="lwg-active.html#Future">Future</a>&nbsp; <b>Submitter:</b>&nbsp;Angelika Langer&nbsp; <b>Date:</b>&nbsp;22 Feb 1999</p>
<p>The following question came from Thorsten Herlemann:</p>

<blockquote>
  <p>You can set a mode when constructing or opening a file-stream or
  filebuf, e.g.  ios::in, ios::out, ios::binary, ... But how can I get
  that mode later on, e.g. in my own operator &lt;&lt; or operator
  &gt;&gt; or when I want to check whether a file-stream or
  file-buffer object passed as parameter is opened for input or output
  or binary? Is there no possibility? Is this a design-error in the
  standard C++ library? </p>
</blockquote>

<p>It is indeed impossible to find out what a stream's or stream
buffer's open mode is, and without that knowledge you don't know
how certain operations behave. Just think of the append mode. </p>

<p>Both streams and stream buffers should have a <tt>mode()</tt> function that returns the
current open mode setting. </p>
<p><b>Proposed resolution:</b></p>
<p>For stream buffers, add a function to the base class as a non-virtual function
qualified as const to 27.5.2 <a href="lib-iostreams.html#lib.streambuf"> [lib.streambuf]</a>:</p>

<p>&nbsp;&nbsp;&nbsp;&nbsp;<tt>openmode mode() const</tt>;</p>

<p><b>&nbsp;&nbsp;&nbsp; Returns</b> the current open mode.</p>

<p>With streams, I'm not sure what to suggest. In principle, the mode
could already be returned by <tt>ios_base</tt>, but the mode is only
initialized for file and string stream objects, unless I'm overlooking
anything. For this reason it should be added to the most derived
stream classes. Alternatively, it could be added to <tt>basic_ios</tt>
and would be default initialized in <tt>basic_ios&lt;&gt;::init()</tt>.</p>
<p><b>Rationale:</b></p>
<p>This might be an interesting extension for some future, but it is
not a defect in the current standard. The Proposed Resolution is
retained for future reference.</p>
<hr>
<a name="131"><h3>131.&nbsp;list::splice throws nothing</h3></a><p><b>Section:</b>&nbsp;23.2.2.4 <a href="lib-containers.html#lib.list.ops"> [lib.list.ops]</a>&nbsp; <b>Status:</b>&nbsp;<a href="lwg-active.html#NAD">NAD</a>&nbsp; <b>Submitter:</b>&nbsp;Howard Hinnant&nbsp; <b>Date:</b>&nbsp;6 Mar 1999</p>
<p>What happens if a splice operation causes the size() of a list to grow 
beyond max_size()?</p>
<p><b>Proposed resolution:</b></p>
<p><b>Rationale:</b></p>
<p>Size() cannot grow beyond max_size().&nbsp; </p>
<hr>
<a name="135"><h3>135.&nbsp;basic_iostream doubly initialized</h3></a><p><b>Section:</b>&nbsp;27.6.1.5.1 <a href="lib-iostreams.html#lib.iostream.cons"> [lib.iostream.cons]</a>&nbsp; <b>Status:</b>&nbsp;<a href="lwg-active.html#NAD">NAD</a>&nbsp; <b>Submitter:</b>&nbsp;Howard Hinnant&nbsp; <b>Date:</b>&nbsp;6 Mar 1999</p>
<p>-1- Effects Constructs an object of class basic_iostream, assigning
initial values to the base classes by calling
basic_istream&lt;charT,traits&gt;(sb) (lib.istream) and
basic_ostream&lt;charT,traits&gt;(sb) (lib.ostream)</p>

<p>The called for basic_istream and basic_ostream constructors call
init(sb). This means that the basic_iostream's virtual base class is
initialized twice.</p>
<p><b>Proposed resolution:</b></p>
<p>Change 27.6.1.5.1, paragraph 1 to:</p>

<p>-1- Effects Constructs an object of class basic_iostream, assigning
initial values to the base classes by calling
basic_istream&lt;charT,traits&gt;(sb) (lib.istream).</p>
<p><b>Rationale:</b></p>
<p>The LWG agreed that the <tt> init()</tt> function is called
twice, but said that this is harmless and so not a defect in the
standard.</p>
<hr>
<a name="138"><h3>138.&nbsp;Class ctype_byname&lt;char&gt; redundant and misleading</h3></a><p><b>Section:</b>&nbsp;22.2.1.4 <a href="lib-locales.html#lib.locale.ctype.byname.special"> [lib.locale.ctype.byname.special]</a>&nbsp; <b>Status:</b>&nbsp;<a href="lwg-active.html#NAD">NAD</a>&nbsp;<a href="lwg-active.html#Future">Future</a>&nbsp; <b>Submitter:</b>&nbsp;Angelika Langer&nbsp; <b>Date:</b>&nbsp;March 18, 1999</p>
<p>Section 22.2.1.4 <a href="lib-locales.html#lib.locale.ctype.byname.special"> [lib.locale.ctype.byname.special]</a> specifies that
ctype_byname&lt;char&gt; must be a specialization of the ctype_byname
template.</p>

<p>It is common practice in the standard that specializations of class templates are only
mentioned where the interface of the specialization deviates from the interface of the
template that it is a specialization of. Otherwise, the fact whether or not a required
instantiation is an actual instantiation or a specialization is left open as an
implementation detail. </p>

<p>Clause 22.2.1.4 deviates from that practice and for that reason is misleading. The
fact, that ctype_byname&lt;char&gt; is specified as a specialization suggests that there
must be something "special" about it, but it has the exact same interface as the
ctype_byname template. Clause 22.2.1.4 does not have any explanatory value, is at best
redundant, at worst misleading - unless I am missing anything. </p>

<p>Naturally, an implementation will most likely implement ctype_byname&lt;char&gt; as a
specialization, because the base class ctype&lt;char&gt; is a specialization with an
interface different from the ctype template, but that's an implementation detail and need
not be mentioned in the standard. </p>
<p><b>Proposed resolution:</b></p>
<p><b>Rationale:</b></p>
<p> The standard as written is mildly misleading, but the correct fix
is to deal with the underlying problem in the ctype_byname base class,
not in the specialization. See issue <a href="lwg-defects.html#228">228</a>.</p>
<hr>
<a name="140"><h3>140.&nbsp;map&lt;Key, T&gt;::value_type does not satisfy the assignable requirement</h3></a><p><b>Section:</b>&nbsp;23.3.1 <a href="lib-containers.html#lib.map"> [lib.map]</a>&nbsp; <b>Status:</b>&nbsp;<a href="lwg-active.html#NAD">NAD</a>&nbsp;<a href="lwg-active.html#Future">Future</a>&nbsp; <b>Submitter:</b>&nbsp;Mark Mitchell&nbsp; <b>Date:</b>&nbsp;14 Apr 1999</p>
<blockquote>
  <p>23.1 <a href="lib-containers.html#lib.container.requirements"> [lib.container.requirements]</a><br>
  <br>
  expression&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; return type
  &nbsp;&nbsp;&nbsp;&nbsp; pre/post-condition<br>
  -------------&nbsp;&nbsp;&nbsp;&nbsp; ----------- &nbsp;&nbsp;&nbsp;&nbsp;
  -------------------<br>
  X::value_type&nbsp;&nbsp;&nbsp; T
  &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
  T is assignable<br>
  <br>
  23.3.1 <a href="lib-containers.html#lib.map"> [lib.map]</a><br>
  <br>
  A map satisfies all the requirements of a container.<br>
  <br>
  For a map&lt;Key, T&gt; ... the value_type is pair&lt;const Key, T&gt;.</p>
</blockquote>

<p>There's a contradiction here. In particular, `pair&lt;const Key,
T&gt;' is not assignable; the `const Key' cannot be assigned
to. So,&nbsp; map&lt;Key, T&gt;::value_type does not satisfy the
assignable requirement imposed by a container.</p>

<p><i>[See issue <a href="lwg-defects.html#103">103</a> for the slightly related issue of
modification of set keys.]</i></p>
<p><b>Proposed resolution:</b></p>
<p><b>Rationale:</b></p>
<p>The LWG believes that the standard is inconsistent, but that this
is a design problem rather than a strict defect. May wish to
reconsider for the next standard.</p>
<hr>
<a name="143"><h3>143.&nbsp;C .h header wording unclear</h3></a><p><b>Section:</b>&nbsp;D.5 <a href="future.html#depr.c.headers"> [depr.c.headers]</a>&nbsp; <b>Status:</b>&nbsp;<a href="lwg-active.html#NAD">NAD</a>&nbsp; <b>Submitter:</b>&nbsp;Christophe de Dinechin&nbsp; <b>Date:</b>&nbsp;4 May 1999</p>
<p>[depr.c.headers] paragraph 2 reads:</p>

<blockquote>

<p>Each C header, whose name has the form name.h, behaves as if each
name placed in the Standard library namespace by the corresponding
cname header is also placed within the namespace scope of the
namespace std and is followed by an explicit using-declaration
(_namespace.udecl_)</p>

</blockquote>

<p>I think it should mention the global name space somewhere...&nbsp;
Currently, it indicates that name placed in std is also placed in
std...</p>

<p>I don't know what is the correct wording. For instance, if struct
tm is defined in time.h, ctime declares std::tm. However, the current
wording seems ambiguous regarding which of the following would occur
for use of both ctime and time.h:</p>

<blockquote>
  <pre>// version 1:
namespace std {
        struct tm { ... };
}
using std::tm;

// version 2:
struct tm { ... };
namespace std {
        using ::tm;
}

// version 3:
struct tm { ... };
namespace std {
        struct tm { ... };
}</pre>
</blockquote>

<p>I think version 1 is intended.</p>

<p><i>[Kona: The LWG agreed that the wording is not clear. It also
agreed that version 1 is intended, version 2 is not equivalent to
version 1, and version 3 is clearly not intended. The example below
was constructed by Nathan Myers to illustrate why version 2 is not
equivalent to version 1.</i></p>

<p><i>Although not equivalent, the LWG is unsure if (2) is enough of
a problem to be prohibited. Points discussed in favor of allowing
(2):</i></p>

<blockquote>
  <ul>
    <li><i>It may be a convenience to implementors.</i></li>
    <li><i>The only cases that fail are structs, of which the C library
      contains only a few.</i></li>
  </ul>
</blockquote>

<p><i>]</i></p>

<p><b>Example:</b></p>

<blockquote>

<pre>#include &lt;time.h&gt;
#include &lt;utility&gt;

int main() {
    std::tm * t;
    make_pair( t, t ); // okay with version 1 due to Koenig lookup
                       // fails with version 2; make_pair not found
    return 0;
}</pre>

</blockquote>
<p><b>Proposed resolution:</b></p>

<p>Replace D.5 <a href="future.html#depr.c.headers"> [depr.c.headers]</a> paragraph 2 with:</p>

<blockquote>

<p> Each C header, whose name has the form name.h, behaves as if each
name placed in the Standard library namespace by the corresponding
cname header is also placed within the namespace scope of the
namespace std by name.h and is followed by an explicit
using-declaration (_namespace.udecl_) in global scope.</p>

</blockquote>

<p><b>Rationale:</b></p>
<p> The current wording in the standard is the result of a difficult
compromise that averted delay of the standard. Based on discussions
in Tokyo it is clear that there is no still no consensus on stricter
wording, so the issue has been closed. It is suggested that users not
write code that depends on Koenig lookup of C library functions.</p>
<hr>
<a name="145"><h3>145.&nbsp;adjustfield lacks default value</h3></a><p><b>Section:</b>&nbsp;27.4.4.1 <a href="lib-iostreams.html#lib.basic.ios.cons"> [lib.basic.ios.cons]</a>&nbsp; <b>Status:</b>&nbsp;<a href="lwg-active.html#NAD">NAD</a>&nbsp; <b>Submitter:</b>&nbsp;Angelika Langer&nbsp; <b>Date:</b>&nbsp;12 May 1999</p>
<p>There is no initial value for the adjustfield defined, although
many people believe that the default adjustment were right. This is a
common misunderstanding. The standard only defines that, if no
adjustment is specified, all the predefined inserters must add fill
characters before the actual value, which is "as if" the
right flag were set. The flag itself need not be set.</p>

<p>When you implement a user-defined inserter you cannot rely on right
being the default setting for the adjustfield. Instead, you must be
prepared to find none of the flags set and must keep in mind that in
this case you should make your inserter behave "as if" the
right flag were set. This is surprising to many people and complicates
matters more than necessary.</p>

<p>Unless there is a good reason why the adjustfield should not be
initialized I would suggest to give it the default value that
everybody expects anyway.</p>

<p><b>Proposed resolution:</b></p>
<p><b>Rationale:</b></p>
<p>This is not a defect. It is deliberate that the default is no bits
set. Consider Arabic or Hebrew, for example. See 22.2.2.2.2 <a href="lib-locales.html#lib.facet.num.put.virtuals"> [lib.facet.num.put.virtuals]</a> paragraph 19, Table 61 - Fill padding.</p>
<hr>
<a name="149"><h3>149.&nbsp;Insert should return iterator to first element inserted</h3></a><p><b>Section:</b>&nbsp;23.1.1 <a href="lib-containers.html#lib.sequence.reqmts"> [lib.sequence.reqmts]</a>&nbsp; <b>Status:</b>&nbsp;<a href="lwg-active.html#NAD">NAD</a>&nbsp;<a href="lwg-active.html#Future">Future</a>&nbsp; <b>Submitter:</b>&nbsp;Andrew Koenig&nbsp; <b>Date:</b>&nbsp;28 Jun 1999</p>
<p>Suppose that c and c1 are sequential containers and i is an
iterator that refers to an element of c.  Then I can insert a copy of
c1's elements into c ahead of element i by executing </p>

<blockquote>

<pre>c.insert(i, c1.begin(), c1.end());</pre>

</blockquote>

<p>If c is a vector, it is fairly easy for me to find out where the
newly inserted elements are, even though i is now invalid: </p>

<blockquote>

<pre>size_t i_loc = i - c.begin();
c.insert(i, c1.begin(), c1.end());</pre>

</blockquote>

<p>and now the first inserted element is at c.begin()+i_loc and one
past the last is at c.begin()+i_loc+c1.size().<br>
<br>
But what if c is a list?  I can still find the location of one    past the last inserted element, because i is still valid.    To find the location of the first inserted element, though,    I must execute something like </p>

<blockquote>

<pre>for (size_t n = c1.size(); n; --n)
   --i;</pre>

</blockquote>

<p>because i is now no longer a random-access iterator.<br>
<br>
Alternatively, I might write something like </p>

<blockquote>

<pre>bool first = i == c.begin();
list&lt;T&gt;::iterator j = i;
if (!first) --j;
c.insert(i, c1.begin(), c1.end());
if (first)
   j = c.begin();
else
   ++j;</pre>

</blockquote>

<p>which, although wretched, requires less overhead.<br>
<br>
But I think the right solution is to change the definition of insert
so that instead of returning void, it returns an iterator that refers
to the first element inserted, if any, and otherwise is a copy of its
first argument.&nbsp; </p>
<p><b>Proposed resolution:</b></p>
<p><b>Rationale:</b></p>
<p>The LWG believes this was an intentional design decision and so is
not a defect. It may be worth revisiting for the next standard.</p>
<hr>
<a name="157"><h3>157.&nbsp;Meaningless error handling for <tt>pword()</tt> and <tt>iword()</tt>
</h3></a><p><b>Section:</b>&nbsp;27.4.2.5 <a href="lib-iostreams.html#lib.ios.base.storage"> [lib.ios.base.storage]</a>&nbsp; <b>Status:</b>&nbsp;<a href="lwg-active.html#Dup">Dup</a>&nbsp; <b>Submitter:</b>&nbsp;Dietmar K&uuml;hl&nbsp; <b>Date:</b>&nbsp;20 Jul 1999</p>
<p>According to paragraphs 2 and 4 of 27.4.2.5 <a href="lib-iostreams.html#lib.ios.base.storage"> [lib.ios.base.storage]</a>, the
functions <tt>iword()</tt> and <tt>pword()</tt> "set the
<tt>badbit</tt> (which might throw an exception)" on
failure. ... but what does it mean for <tt>ios_base</tt> to set the
<tt>badbit</tt>? The state facilities of the IOStream library are
defined in <tt>basic_ios</tt>, a derived class! It would be possible
to attempt a down cast but then it would be necessary to know the
character type used...</p>
<p><b>Proposed resolution:</b></p>
<p><b>Rationale:</b></p>
<p>Duplicate. See issue <a href="lwg-defects.html#41">41</a>.</p>
<hr>
<a name="162"><h3>162.&nbsp;Really "formatted input functions"?</h3></a><p><b>Section:</b>&nbsp;27.6.1.2.3 <a href="lib-iostreams.html#lib.istream::extractors"> [lib.istream::extractors]</a>&nbsp; <b>Status:</b>&nbsp;<a href="lwg-active.html#Dup">Dup</a>&nbsp; <b>Submitter:</b>&nbsp;Dietmar K&uuml;hl&nbsp; <b>Date:</b>&nbsp;20 Jul 1999</p>
<p>It appears to be somewhat nonsensical to consider the functions
defined in the paragraphs 1 to 5 to be "Formatted input
function" but since these functions are defined in a section
labeled "Formatted input functions" it is unclear to me
whether these operators are considered formatted input functions which
have to conform to the "common requirements" from 27.6.1.2.1 <a href="lib-iostreams.html#lib.istream.formatted.reqmts"> [lib.istream.formatted.reqmts]</a>: If this is the case, all manipulators, not just
<tt>ws</tt>, would skip whitespace unless <tt>noskipws</tt> is set
(... but setting <tt>noskipws</tt> using the manipulator syntax would
also skip whitespace :-)</p>

<p>See also issue <a href="lwg-closed.html#166">166</a> for the same problem in formatted
output</p>
<p><b>Proposed resolution:</b></p>
<p><b>Rationale:</b></p>
<p>Duplicate. See issue <a href="lwg-defects.html#60">60</a>.</p>
<hr>
<a name="163"><h3>163.&nbsp;Return of <tt>gcount()</tt> after a call to <tt>gcount</tt>
</h3></a><p><b>Section:</b>&nbsp;27.6.1.3 <a href="lib-iostreams.html#lib.istream.unformatted"> [lib.istream.unformatted]</a>&nbsp; <b>Status:</b>&nbsp;<a href="lwg-active.html#Dup">Dup</a>&nbsp; <b>Submitter:</b>&nbsp;Dietmar K&uuml;hl&nbsp; <b>Date:</b>&nbsp;20 Jul 1999</p>
<p>It is not clear which functions are to be considered unformatted
input functions. As written, it seems that all functions in 27.6.1.3 <a href="lib-iostreams.html#lib.istream.unformatted"> [lib.istream.unformatted]</a> are unformatted input functions. However, it does not
really make much sense to construct a sentry object for
<tt>gcount()</tt>, <tt>sync()</tt>, ... Also it is unclear what
happens to the <tt>gcount()</tt> if eg. <tt>gcount()</tt>,
<tt>putback()</tt>, <tt>unget()</tt>, or <tt>sync()</tt> is called:
These functions don't extract characters, some of them even
"unextract" a character. Should this still be reflected in
<tt>gcount()</tt>? Of course, it could be read as if after a call to
<tt>gcount()</tt> <tt>gcount()</tt> return <tt>0</tt> (the last
unformatted input function, <tt>gcount()</tt>, didn't extract any
character) and after a call to <tt>putback()</tt> <tt>gcount()</tt>
returns <tt>-1</tt> (the last unformatted input function
<tt>putback()</tt> did "extract" back into the
stream). Correspondingly for <tt>unget()</tt>. Is this what is
intended?  If so, this should be clarified. Otherwise, a corresponding
clarification should be used.</p>
<p><b>Proposed resolution:</b></p>
<p><b>Rationale:</b></p>
<p>Duplicate.&nbsp; See issue <a href="lwg-defects.html#60">60</a>.</p>
<hr>
<a name="166"><h3>166.&nbsp;Really "formatted output functions"?</h3></a><p><b>Section:</b>&nbsp;27.6.2.5.3 <a href="lib-iostreams.html#lib.ostream.inserters"> [lib.ostream.inserters]</a>&nbsp; <b>Status:</b>&nbsp;<a href="lwg-active.html#Dup">Dup</a>&nbsp; <b>Submitter:</b>&nbsp;Dietmar K&uuml;hl&nbsp; <b>Date:</b>&nbsp;20 Jul 1999</p>
<p>From 27.6.2.5.1 <a href="lib-iostreams.html#lib.ostream.formatted.reqmts"> [lib.ostream.formatted.reqmts]</a> it appears that all the functions
defined in 27.6.2.5.3 <a href="lib-iostreams.html#lib.ostream.inserters"> [lib.ostream.inserters]</a> have to construct a
<tt>sentry</tt> object. Is this really intended?</p> 

<p>This is basically the same problem as issue <a href="lwg-closed.html#162">162</a> but
for output instead of input.</p>
<p><b>Proposed resolution:</b></p>
<p><b>Rationale:</b></p>
<p>Duplicate. See issue <a href="lwg-defects.html#60">60</a>.</p>
<hr>
<a name="177"><h3>177.&nbsp;Complex operators cannot be explicitly instantiated</h3></a><p><b>Section:</b>&nbsp;26.2.6 <a href="lib-numerics.html#lib.complex.ops"> [lib.complex.ops]</a>&nbsp; <b>Status:</b>&nbsp;<a href="lwg-active.html#NAD">NAD</a>&nbsp; <b>Submitter:</b>&nbsp;Judy Ward&nbsp; <b>Date:</b>&nbsp;2 Jul 1999</p>
<p>A user who tries to explicitly instantiate a complex non-member operator will
get compilation errors. Below is a simplified example of the reason why. The
problem is that iterator_traits cannot be instantiated on a non-pointer type
like float, yet when the compiler is trying to decide which operator+ needs to
be instantiated it must instantiate the declaration to figure out the first
argument type of a reverse_iterator operator.</p>
<pre>namespace std {
template &lt;class Iterator&gt; 
struct iterator_traits
{
    typedef typename Iterator::value_type value_type;
};

template &lt;class T&gt; class reverse_iterator;

// reverse_iterator operator+
template &lt;class T&gt; 
reverse_iterator&lt;T&gt; operator+
(typename iterator_traits&lt;T&gt;::difference_type, const reverse_iterator&lt;T&gt;&amp;);

template &lt;class T&gt; struct complex {};

// complex operator +
template &lt;class T&gt;
complex&lt;T&gt; operator+ (const T&amp; lhs, const complex&lt;T&gt;&amp; rhs) 
{ return complex&lt;T&gt;();} 
}

// request for explicit instantiation
template std::complex&lt;float&gt; std::operator+&lt;float&gt;(const float&amp;, 
     const std::complex&lt;float&gt;&amp;);</pre>
<p>See also c++-stdlib reflector messages: lib-6814, 6815, 6816.</p>
<p><b>Proposed resolution:</b></p>
<p><b>Rationale:</b></p>
<p>Implementors can make minor changes and the example will
work. Users are not affected in any case.</p> <p>According to John
Spicer, It is possible to explicitly instantiate these operators using
different syntax: change "std::operator+&lt;float&gt;" to
"std::operator+".</p>

<p>The proposed resolution of issue 120 is that users will not be able
to explicitly instantiate standard library templates. If that
resolution is accepted then library implementors will be the only ones
that will be affected by this problem, and they must use the indicated
syntax.</p>
<hr>
<a name="178"><h3>178.&nbsp;Should clog and cerr initially be tied to cout?</h3></a><p><b>Section:</b>&nbsp;27.3.1 <a href="lib-iostreams.html#lib.narrow.stream.objects"> [lib.narrow.stream.objects]</a>&nbsp; <b>Status:</b>&nbsp;<a href="lwg-active.html#NAD">NAD</a>&nbsp; <b>Submitter:</b>&nbsp;Judy Ward&nbsp; <b>Date:</b>&nbsp;2 Jul 1999</p>
<p>
Section 27.3.1 says "After the object cerr is initialized,
cerr.flags() &amp; unitbuf is nonzero. Its state is otherwise the same as
required for ios_base::init (lib.basic.ios.cons).  It doesn't say
anything about the the state of clog.  So this means that calling
cerr.tie() and clog.tie() should return 0 (see Table 89 for
ios_base::init effects).
</p>
<p>
Neither of the popular standard library implementations
that I tried does this, they both tie cerr and clog
to &amp;cout. I would think that would be what users expect.
</p>
<p><b>Proposed resolution:</b></p>
<p><b>Rationale:</b></p>
<p>The standard is clear as written.</p>
<p>27.3.1/5 says that "After the object cerr is initialized, cerr.flags()
&amp; unitbuf is nonzero. Its state is otherwise the same as required for
ios_base::init (27.4.4.1)." Table 89 in 27.4.4.1, which gives the
postconditions of basic_ios::init(), says that tie() is 0. (Other issues correct
ios_base::init to basic_ios::init().)</p>
<hr>
<a name="180"><h3>180.&nbsp;Container member iterator arguments constness has unintended consequences</h3></a><p><b>Section:</b>&nbsp;23 <a href="lib-containers.html#lib.containers"> [lib.containers]</a>&nbsp; <b>Status:</b>&nbsp;<a href="lwg-active.html#NAD">NAD</a>&nbsp;<a href="lwg-active.html#Future">Future</a>&nbsp; <b>Submitter:</b>&nbsp;Dave Abrahams&nbsp; <b>Date:</b>&nbsp;1 Jul 1999</p>
<p>It is the constness of the container which should control whether
it can be modified through a member function such as erase(), not the
constness of the iterators. The iterators only serve to give
positioning information.</p>

<p>Here's a simple and typical example problem which is currently very
difficult or impossible to solve without the change proposed
below.</p>

<p>Wrap a standard container C in a class W which allows clients to
find and read (but not modify) a subrange of (C.begin(), C.end()]. The
only modification clients are allowed to make to elements in this
subrange is to erase them from C through the use of a member function
of W.</p>
<p><b>Proposed resolution:</b></p>
<p>Change all non-const iterator parameters of standard library
container member functions to accept const_iterator parameters.
Note that this change applies to all library clauses, including
strings.</p>

<p>For example, in   21.3.5.5  change:<br>
<br>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; <tt>iterator erase(iterator p);</tt><br>
<br>
to:<br>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; <tt>iterator erase(const_iterator p);</tt>
</p>
<p><b>Rationale:</b></p>
<p>The issue was discussed at length. It was generally agreed that 1)
There is no major technical argument against the change (although
there is a minor argument that some obscure programs may break), and
2) Such a change would not break const correctness. The concerns about
making the change were 1) it is user detectable (although only in
boundary cases), 2) it changes a large number of signatures, and 3) it
seems more of a design issue that an out-and-out defect.</p>

<p>The LWG believes that this issue should be considered as part of a
general review of const issues for the next revision of the
standard. Also see issue <a href="lwg-defects.html#200">200</a>.</p>
<hr>
<a name="188"><h3>188.&nbsp;valarray helpers missing augmented assignment operators</h3></a><p><b>Section:</b>&nbsp;26.3.2.6 <a href="lib-numerics.html#lib.valarray.cassign"> [lib.valarray.cassign]</a>&nbsp; <b>Status:</b>&nbsp;<a href="lwg-active.html#NAD">NAD</a>&nbsp;<a href="lwg-active.html#Future">Future</a>&nbsp; <b>Submitter:</b>&nbsp;Gabriel Dos Reis&nbsp; <b>Date:</b>&nbsp;15 Aug 1999</p>
<p>26.3.2.6 defines augmented assignment operators
valarray&lt;T&gt;::op=(const T&amp;), but fails to provide
corresponding versions for the helper classes. Thus making the
following illegal:</p>
<blockquote>
<pre>#include &lt;valarray&gt;

int main()
{
std::valarray&lt;double&gt; v(3.14, 1999);

v[99] *= 2.0; // Ok

std::slice s(0, 50, 2);

v[s] *= 2.0; // ERROR
}</pre>
</blockquote>
<p>I can't understand the intent of that omission.  It makes the
valarray library less intuitive and less useful.</p>
<p><b>Proposed resolution:</b></p>
<p><b>Rationale:</b></p>
<p>Although perhaps an unfortunate
design decision, the omission is not a defect in the current
standard.&nbsp; A future standard may wish to add the missing
operators.</p>
<hr>
<a name="190"><h3>190.&nbsp;min() and max() functions should be std::binary_functions</h3></a><p><b>Section:</b>&nbsp;25.3.7 <a href="lib-algorithms.html#lib.alg.min.max"> [lib.alg.min.max]</a>&nbsp; <b>Status:</b>&nbsp;<a href="lwg-active.html#NAD">NAD</a>&nbsp;<a href="lwg-active.html#Future">Future</a>&nbsp; <b>Submitter:</b>&nbsp;Mark Rintoul&nbsp; <b>Date:</b>&nbsp;26 Aug 1999</p>
<p>Both std::min and std::max are defined as template functions.  This
is very different than the definition of std::plus (and similar
structs) which are defined as function objects which inherit
std::binary_function.<br>
<br>
        This lack of inheritance leaves std::min and std::max somewhat useless in standard library algorithms which require
a function object that inherits std::binary_function.</p>
<p><b>Proposed resolution:</b></p>
<p><b>Rationale:</b></p>
<p>Although perhaps an unfortunate design decision, the omission is not a defect
in the current standard.&nbsp; A future standard may wish to consider additional
function objects.</p>
<hr>
<a name="191"><h3>191.&nbsp;Unclear complexity for algorithms such as binary search</h3></a><p><b>Section:</b>&nbsp;25.3.3 <a href="lib-algorithms.html#lib.alg.binary.search"> [lib.alg.binary.search]</a>&nbsp; <b>Status:</b>&nbsp;<a href="lwg-active.html#NAD">NAD</a>&nbsp; <b>Submitter:</b>&nbsp;Nico Josuttis&nbsp; <b>Date:</b>&nbsp;10 Oct 1999</p>
<p>The complexity of binary_search() is stated as "At most
log(last-first) + 2 comparisons", which seems to say that the
algorithm has logarithmic complexity. However, this algorithms is
defined for forward iterators. And for forward iterators, the need to
step element-by-element results into linear complexity. But such a
statement is missing in the standard. The same applies to
lower_bound(), upper_bound(), and equal_range().&nbsp;<br>
<br>
However, strictly speaking the standard contains no bug here. So this
might considered to be a clarification or improvement.
</p>
<p><b>Proposed resolution:</b></p>
<p><b>Rationale:</b></p>
<p>The complexity is expressed in terms of comparisons, and that
complexity can be met even if the number of iterators accessed is
linear. Paragraph 1 already says exactly what happens to
iterators.</p>
<hr>
<a name="192"><h3>192.&nbsp;a.insert(p,t) is inefficient and overconstrained</h3></a><p><b>Section:</b>&nbsp;23.1.2 <a href="lib-containers.html#lib.associative.reqmts"> [lib.associative.reqmts]</a>&nbsp; <b>Status:</b>&nbsp;<a href="lwg-active.html#NAD">NAD</a>&nbsp; <b>Submitter:</b>&nbsp;Ed Brey&nbsp; <b>Date:</b>&nbsp;6 Jun 1999</p>
<p>As defined in 23.1.2, paragraph 7 (table 69), a.insert(p,t) suffers from
several problems:</p>
<table border="1" cellpadding="5">
  <tr>
    <td><b>expression</b></td>
    <td><b>return type</b></td>
    <td><b>pre/post-condition</b></td>
    <td><b>complexity</b></td>
  </tr>
  <tr>
    <td><tt>a.insert(p,t)</tt></td>
    <td><tt>iterator</tt></td>
    <td>inserts t if and only if there is no element with key equivalent to the key of 
       t in containers with unique keys; always inserts t in containers with equivalent 
       keys. always returns the iterator pointing to the element with key equivalent to 
       the key of t . iterator p is a hint pointing to where the insert should start to search.</td>
    <td>logarithmic in general, but amortized constant if t is inserted right after p .</td>
  </tr>
</table>
<p>1. For a container with unique keys, only logarithmic complexity is
guaranteed if no element is inserted, even though constant complexity is always
possible if p points to an element equivalent to t.</p>
<p>2. For a container with equivalent keys, the amortized constant complexity
guarantee is only useful if no key equivalent to t exists in the container.
Otherwise, the insertion could occur in one of multiple locations, at least one
of which would not be right after p.</p>
<p>3. By guaranteeing amortized constant complexity only when t is inserted
after p, it is impossible to guarantee constant complexity if t is inserted at
the beginning of the container. Such a problem would not exist if amortized
constant complexity was guaranteed if t is inserted before p, since there is
always some p immediately before which an insert can take place.</p>
<p>4. For a container with equivalent keys, p does not allow specification of
where to insert the element, but rather only acts as a hint for improving
performance. This negates the added functionality that p would provide if it
specified where within a sequence of equivalent keys the insertion should occur.
Specifying the insert location provides more control to the user, while
providing no disadvantage to the container implementation.</p>
<p><b>Proposed resolution:</b></p>
<p>In 23.1.2 <a href="lib-containers.html#lib.associative.reqmts"> [lib.associative.reqmts]</a> paragraph 7, replace the row in table 69
for a.insert(p,t) with the following two rows:</p>
<table border="1" cellpadding="5">
  <tr>
    <td><b>expression</b></td>
    <td><b>return type</b></td>
    <td><b>pre/post-condition</b></td>
    <td><b>complexity</b></td>
  </tr>
  <tr>
    <td><tt>a_uniq.insert(p,t)</tt></td>
    <td><tt>iterator</tt></td>
    <td>inserts t if and only if there is no element with key equivalent to the
      key of t. returns the iterator pointing to the element with key equivalent
      to the key of t.</td>
    <td>logarithmic in general, but amortized constant if t is inserted right
      before p or p points to an element with key equivalent to t.</td>
  </tr>
  <tr>
    <td><tt>a_eq.insert(p,t)</tt></td>
    <td><tt>iterator</tt></td>
    <td>inserts t and returns the iterator pointing to the newly inserted
      element. t is inserted right before p if doing so preserves the container
      ordering.</td>
    <td>logarithmic in general, but amortized constant if t is inserted right
      before p.</td>
  </tr>
</table>

<p><b>Rationale:</b></p>
<p>Too big a change.&nbsp; Furthermore, implementors report checking
both before p and after p, and don't want to change this behavior.</p>
<hr>
<a name="194"><h3>194.&nbsp;rdbuf() functions poorly specified</h3></a><p><b>Section:</b>&nbsp;27.4.4 <a href="lib-iostreams.html#lib.ios"> [lib.ios]</a>&nbsp; <b>Status:</b>&nbsp;<a href="lwg-active.html#NAD">NAD</a>&nbsp; <b>Submitter:</b>&nbsp;Steve Clamage&nbsp; <b>Date:</b>&nbsp;7 Sep 1999</p>
<p>In classic iostreams, base class ios had an rdbuf function that returned a
pointer to the associated streambuf. Each derived class had its own rdbuf
function that returned a pointer of a type reflecting the actual type derived
from streambuf. Because in ARM C++, virtual function overrides had to have the
same return type, rdbuf could not be virtual.</p>
<p>In standard iostreams, we retain the non-virtual rdbuf function design, and
in addition have an overloaded rdbuf function that sets the buffer pointer.
There is no need for the second function to be virtual nor to be implemented in
derived classes.</p>
<p>Minor question: Was there a specific reason not to make the original rdbuf
function virtual?</p>
<p>Major problem: Friendly compilers warn about functions in derived classes
that hide base-class overloads. Any standard implementation of iostreams will
result in such a warning on each of the iostream classes, because of the
ill-considered decision to overload rdbuf only in a base class.</p>
<p>In addition, users of the second rdbuf function must use explicit
qualification or a cast to call it from derived classes. An explicit
qualification or cast to basic_ios would prevent access to any later overriding
version if there was one.</p>
<p>What I'd like to do in an implementation is add a using- declaration for the
second rdbuf function in each derived class. It would eliminate warnings about
hiding functions, and would enable access without using explicit qualification.
Such a change I don't think would change the behavior of any valid program, but
would allow invalid programs to compile:</p>
<blockquote>
  <pre> filebuf mybuf;
 fstream f;
 f.rdbuf(mybuf); // should be an error, no visible rdbuf</pre>
</blockquote>
<p>I'd like to suggest this problem as a defect, with the proposed resolution to
require the equivalent of a using-declaration for the rdbuf function that is not
replaced in a later derived class. We could discuss whether replacing the
function should be allowed.</p>
<p><b>Proposed resolution:</b></p>
<p><b>Rationale:</b></p>
<p>For historical reasons, the standard is correct as written. There is a subtle difference between the base
class <tt> rdbuf()</tt> and derived class <tt>rdbuf()</tt>. The derived
class <tt> rdbuf()</tt> always returns the original streambuf, whereas the base class
<tt> rdbuf()</tt> will return the "current streambuf" if that has been changed by the variant you mention.</p>

<p>Permission is not required to add such an extension.  See 
17.4.4.4 <a href="lib-intro.html#lib.member.functions"> [lib.member.functions]</a>.</p>
<hr>
<a name="196"><h3>196.&nbsp;Placement new example has alignment problems</h3></a><p><b>Section:</b>&nbsp;18.4.1.3 <a href="lib-support.html#lib.new.delete.placement"> [lib.new.delete.placement]</a>&nbsp; <b>Status:</b>&nbsp;<a href="lwg-active.html#Dup">Dup</a>&nbsp; <b>Submitter:</b>&nbsp;Herb Sutter&nbsp; <b>Date:</b>&nbsp;15 Dec 1998</p>
<p>The example in 18.4.1.3 <a href="lib-support.html#lib.new.delete.placement"> [lib.new.delete.placement]</a> paragraph 4 reads: </p>

<blockquote>

<p>[Example: This can be useful for constructing an object at a known address:<br>
<br>
<tt>&nbsp;&nbsp; char place[sizeof(Something)];<br>
&nbsp;&nbsp; Something* p = new (place) Something();<br>
<br>
</tt>end example] </p>

</blockquote>

<p>This example has potential alignment problems. </p>
<p><b>Proposed resolution:</b></p>
<p><b>Rationale:</b></p>
<p>Duplicate: see issue <a href="lwg-defects.html#114">114</a>.</p>
<hr>
<a name="203"><h3>203.&nbsp;basic_istream::sentry::sentry() is uninstantiable with ctype&lt;user-defined type&gt;</h3></a><p><b>Section:</b>&nbsp;27.6.1.1.2 <a href="lib-iostreams.html#lib.istream::sentry"> [lib.istream::sentry]</a>&nbsp; <b>Status:</b>&nbsp;<a href="lwg-active.html#NAD">NAD</a>&nbsp; <b>Submitter:</b>&nbsp;Matt McClure and Dietmar K&uuml;hl&nbsp; <b>Date:</b>&nbsp;1 Jan 2000</p>
<p>27.6.1.1.2 Paragraph 4 states:</p>
<blockquote>
  <p>To decide if the character c is a whitespace character, the constructor      
     performs ''as if'' it executes the following code fragment:&nbsp;</p>
  <pre>const ctype&lt;charT&gt;&amp; ctype = use_facet&lt;ctype&lt;charT&gt; &gt;(is.getloc());
if (ctype.is(ctype.space,c)!=0)
// c is a whitespace character.</pre>
</blockquote>

<p> But Table 51 in 22.1.1.1.1 only requires an implementation to
provide specializations for ctype&lt;char&gt; and
ctype&lt;wchar_t&gt;.  If sentry's constructor is implemented using
ctype, it will be uninstantiable for a user-defined character type
charT, unless the implementation has provided non-working (since it
would be impossible to define a correct ctype&lt;charT&gt; specialization
for an arbitrary charT) definitions of ctype's virtual member
functions.</p>

<p>
It seems the intent the standard is that sentry should behave, in
every respect, not just during execution, as if it were implemented
using ctype, with the burden of providing a ctype specialization
falling on the user.  But as it is written, nothing requires the
translation of sentry's constructor to behave as if it used the above
code, and it would seem therefore, that sentry's constructor should be
instantiable for all character types.
</p>

<p> 
Note: If I have misinterpreted the intent of the standard with
respect to sentry's constructor's instantiability, then a note should
be added to the following effect:
</p>

<blockquote>
An implementation is forbidden from using the above code if it renders
the constructor uninstantiable for an otherwise valid character
type.
</blockquote>

<p>In any event, some clarification is needed.</p>

<p><b>Proposed resolution:</b></p>
<p><b>Rationale:</b></p>
<p>It is possible but not easy to instantiate on types other than char
or wchar_t; many things have to be done first. That is by intention
and is not a defect.</p>
<hr>
<a name="204"><h3>204.&nbsp;distance(first, last) when "last" is before "first"</h3></a><p><b>Section:</b>&nbsp;24.3.4 <a href="lib-iterators.html#lib.iterator.operations"> [lib.iterator.operations]</a>&nbsp; <b>Status:</b>&nbsp;<a href="lwg-active.html#NAD">NAD</a>&nbsp; <b>Submitter:</b>&nbsp;Rintala Matti&nbsp; <b>Date:</b>&nbsp;28 Jan 2000</p>
<p>Section 24.3.4 describes the function distance(first, last) (where first and
last are iterators) which calculates "the number of increments or
decrements needed to get from 'first' to 'last'".</p>
<p>The function should work for forward, bidirectional and random access
iterators, and there is a requirement 24.3.4.5 which states that "'last'
must be reachable from 'first'".</p>
<p>With random access iterators the function is easy to implement as "last
- first".</p>
<p>With forward iterators it's clear that 'first' must point to a place before
'last', because otherwise 'last' would not be reachable from 'first'.</p>
<p>But what about bidirectional iterators? There 'last' is reachable from
'first' with the -- operator even if 'last' points to an earlier position than
'first'. However, I cannot see how the distance() function could be implemented
if the implementation does not know which of the iterators points to an earlier
position (you cannot use ++ or -- on either iterator if you don't know which
direction is the "safe way to travel").</p>
<p>The paragraph 24.3.4.1 states that "for ... bidirectional iterators they
use ++ to provide linear time implementations". However, the ++ operator is
not mentioned in the reachability requirement. Furthermore 24.3.4.4 explicitly
mentions that distance() returns the number of increments _or decrements_,
suggesting that it could return a negative number also for bidirectional
iterators when 'last' points to a position before 'first'.</p>
<p>Is a further requirement is needed to state that for forward and
bidirectional iterators "'last' must be reachable from 'first' using the ++
operator". Maybe this requirement might also apply to random access
iterators so that distance() would work the same way for every iterator
category?</p>
<p><b>Proposed resolution:</b></p>
<p><b>Rationale:</b></p>
<p>"Reachable" is defined in the standard in 24.1 <a href="lib-iterators.html#lib.iterator.requirements"> [lib.iterator.requirements]</a> paragraph 6.
The definition is only in terms of operator++(). The LWG sees no defect in
the standard.</p>
<hr>
<a name="205"><h3>205.&nbsp; numeric_limits unclear on how to determine floating point types</h3></a><p><b>Section:</b>&nbsp;18.2.1.2 <a href="lib-support.html#lib.numeric.limits.members"> [lib.numeric.limits.members]</a>&nbsp; <b>Status:</b>&nbsp;<a href="lwg-active.html#NAD">NAD</a>&nbsp; <b>Submitter:</b>&nbsp;Steve Cleary&nbsp; <b>Date:</b>&nbsp;28 Jan 2000</p>
<p>In several places in 18.2.1.2 <a href="lib-support.html#lib.numeric.limits.members"> [lib.numeric.limits.members]</a>, a member is
described as "Meaningful for all floating point types."
However, no clear method of determining a floating point type is
provided.</p>

<p>In 18.2.1.5 <a href="lib-support.html#lib.numeric.special"> [lib.numeric.special]</a>, paragraph 1 states ". . . (for
example, epsilon() is only meaningful if is_integer is
false). . ." which suggests that a type is a floating point type
if is_specialized is true and is_integer is false; however, this is
unclear.</p>

<p>When clarifying this, please keep in mind this need of users: what
exactly is the definition of floating point? Would a fixed point or
rational representation be considered one? I guess my statement here
is that there could also be types that are neither integer or
(strictly) floating point.</p>
<p><b>Proposed resolution:</b></p>
<p><b>Rationale:</b></p>
<p>It is up to the implementor of a user define type to decide if it is a
floating point type.</p>
<hr>
<a name="206"><h3>206.&nbsp;operator new(size_t, nothrow) may become unlinked to ordinary operator new if ordinary version replaced</h3></a><p><b>Section:</b>&nbsp;18.4.1.1 <a href="lib-support.html#lib.new.delete.single"> [lib.new.delete.single]</a>&nbsp; <b>Status:</b>&nbsp;<a href="lwg-active.html#NAD">NAD</a>&nbsp; <b>Submitter:</b>&nbsp;Howard Hinnant&nbsp; <b>Date:</b>&nbsp;29 Aug 1999</p>
<p>As specified, the implementation of the nothrow version of operator
new does not necessarily call the ordinary operator new, but may
instead simply call the same underlying allocator and return a null
pointer instead of throwing an exception in case of failure.</p>

<p>Such an implementation breaks code that replaces the ordinary
version of new, but not the nothrow version. If the ordinary version
of new/delete is replaced, and if the replaced delete is not
compatible with pointers returned from the library versions of new,
then when the replaced delete receives a pointer allocated by the
library new(nothrow), crash follows.</p>

<p>The fix appears to be that the lib version of new(nothrow) must
call the ordinary new. Thus when the ordinary new gets replaced, the
lib version will call the replaced ordinary new and things will
continue to work.</p>

<p>An alternative would be to have the ordinary new call
new(nothrow). This seems sub-optimal to me as the ordinary version of
new is the version most commonly replaced in practice. So one would
still need to replace both ordinary and nothrow versions if one wanted
to replace the ordinary version.</p>

<p>Another alternative is to put in clear text that if one version is
replaced, then the other must also be replaced to maintain
compatibility. Then the proposed resolution below would just be a
quality of implementation issue. There is already such text in
paragraph 7 (under the new(nothrow) version). But this nuance is
easily missed if one reads only the paragraphs relating to the
ordinary new.</p>

<p><b>Proposed resolution:</b></p>
<p><b>Rationale:</b></p>
<p>Yes, they may become unlinked, and that is by design. If a user
replaces one, the user should also replace the other.</p>
<hr>
<a name="207"><h3>207.&nbsp;ctype&lt;char&gt; members return clause incomplete</h3></a><p><b>Section:</b>&nbsp;22.2.1.3.2 <a href="lib-locales.html#lib.facet.ctype.char.members"> [lib.facet.ctype.char.members]</a>&nbsp; <b>Status:</b>&nbsp;<a href="lwg-active.html#Dup">Dup</a>&nbsp; <b>Submitter:</b>&nbsp;Robert Klarer&nbsp; <b>Date:</b>&nbsp;2 Nov 1999</p>
<p>
The <tt>widen</tt> and <tt>narrow</tt> member functions are described
in 22.2.1.3.2, paragraphs 9-11.  In each case we have two overloaded
signatures followed by a <b>Returns</b> clause.  The <b>Returns</b>
clause only describes one of the overloads.
</p>
<p><b>Proposed resolution:</b></p>
<p>Change the returns clause in 22.2.1.3.2 <a href="lib-locales.html#lib.facet.ctype.char.members"> [lib.facet.ctype.char.members]</a>
paragraph 10 from:</p>
<p>&nbsp;&nbsp;&nbsp; Returns: do_widen(low, high, to).</p>

<p>to:</p>
<p>&nbsp;&nbsp;&nbsp; Returns: do_widen(c) or do_widen(low, high, to), 
respectively.</p>

<p>Change the returns clause in 22.2.1.3.2 <a href="lib-locales.html#lib.facet.ctype.char.members"> [lib.facet.ctype.char.members]</a> paragraph 11
from:</p> 
<p>&nbsp;&nbsp;&nbsp; Returns: do_narrow(low, high, to).</p>

<p>to:</p>
<p>&nbsp;&nbsp;&nbsp; Returns: do_narrow(c) or do_narrow(low, high, to), 
respectively.</p>
<p><b>Rationale:</b></p>
<p>Subsumed by issue <a href="lwg-defects.html#153">153</a>, which addresses the same
paragraphs.</p>
<hr>
<a name="213"><h3>213.&nbsp;Math function overloads ambiguous</h3></a><p><b>Section:</b>&nbsp;26.5 <a href="lib-numerics.html#lib.c.math"> [lib.c.math]</a>&nbsp; <b>Status:</b>&nbsp;<a href="lwg-active.html#NAD">NAD</a>&nbsp; <b>Submitter:</b>&nbsp;Nico Josuttis&nbsp; <b>Date:</b>&nbsp;26 Feb 2000</p>
<p>Due to the additional overloaded versions of numeric functions for
float and long double according to Section 26.5, calls such as int x;
std::pow (x, 4) are ambiguous now in a standard conforming
implementation. Current implementations solve this problem very
different (overload for all types, don't overload for float and long
double, use preprocessor, follow the standard and get
ambiguities).</p> <p>This behavior should be standardized or at least
identified as implementation defined.</p>
<p><b>Proposed resolution:</b></p>
<p><b>Rationale:</b></p>
<p>These math issues are an
understood and accepted consequence of the design. They have
been discussed several times in the past. Users must write casts
or write floating point expressions as arguments.</p>
<hr>
<a name="215"><h3>215.&nbsp;Can a map's key_type be const?</h3></a><p><b>Section:</b>&nbsp;23.1.2 <a href="lib-containers.html#lib.associative.reqmts"> [lib.associative.reqmts]</a>&nbsp; <b>Status:</b>&nbsp;<a href="lwg-active.html#NAD">NAD</a>&nbsp; <b>Submitter:</b>&nbsp;Judy Ward&nbsp; <b>Date:</b>&nbsp;29 Feb 2000</p>
<p>A user noticed that this doesn't compile with the Rogue Wave library because
the rb_tree class declares a key_allocator, and allocator&lt;const int&gt; is
not legal, I think:</p>
<blockquote>
  <pre>map &lt; const int, ... &gt; // legal?</pre>
</blockquote>
<p>which made me wonder whether it is legal for a map's key_type to be const. In
email from Matt Austern he said:</p>
<blockquote>
<p>I'm not sure whether it's legal to declare a map with a const key type. I
hadn't thought about that question until a couple weeks ago. My intuitive
feeling is that it ought not to be allowed, and that the standard ought to say
so. It does turn out to work in SGI's library, though, and someone in the
compiler group even used it. Perhaps this deserves to be written up as an issue
too.</p>
</blockquote>
<p><b>Proposed resolution:</b></p>
<p><b>Rationale:</b></p>
<p>The "key is assignable" requirement from table 69 in
23.1.2 <a href="lib-containers.html#lib.associative.reqmts"> [lib.associative.reqmts]</a> already implies the key cannot be const.</p>
<hr>
<a name="216"><h3>216.&nbsp;setbase manipulator description flawed</h3></a><p><b>Section:</b>&nbsp;27.6.3 <a href="lib-iostreams.html#lib.std.manip"> [lib.std.manip]</a>&nbsp; <b>Status:</b>&nbsp;<a href="lwg-active.html#Dup">Dup</a>&nbsp; <b>Submitter:</b>&nbsp;Hyman Rosen&nbsp; <b>Date:</b>&nbsp;29 Feb 2000</p>
<p>27.6.3 <a href="lib-iostreams.html#lib.std.manip"> [lib.std.manip]</a> paragraph 5 says:</p>
<blockquote>
<pre>smanip setbase(int base);</pre>
<p> Returns: An object s of unspecified type such that if out is an
(instance of) basic_ostream then the expression out&lt;&lt;s behaves
as if f(s) were called, in is an (instance of) basic_istream then the
expression in&gt;&gt;s behaves as if f(s) were called. Where f can be
defined as:</p>
<pre>ios_base&amp; f(ios_base&amp; str, int base)
{
  // set basefield
  str.setf(n == 8 ? ios_base::oct :
                n == 10 ? ios_base::dec :
                n == 16 ? ios_base::hex :
                  ios_base::fmtflags(0), ios_base::basefield);
  return str;
}</pre>
</blockquote>
<p>There are two problems here. First, f takes two parameters, so the
description needs to say that out&lt;&lt;s and in&gt;&gt;s behave as if f(s,base)
had been called. Second, f is has a parameter named base, but is written as if
the parameter was named n.</p>
<p>Actually, there's a third problem. The paragraph has grammatical errors.
There needs to be an "and" after the first comma, and the "Where
f" sentence fragment needs to be merged into its preceding sentence. You
may also want to format the function a little better. The formatting above is
more-or-less what the Standard contains.</p>
<p><b>Proposed resolution:</b></p>
<p><b>Rationale:</b></p>
<p>The resolution of this defect is subsumed by the proposed resolution for
issue <a href="lwg-defects.html#193">193</a>.</p>

<p><i>[Tokyo: The LWG agrees that this is a defect and notes that it
occurs additional places in the section, all requiring fixes.]</i></p>
<hr>
<a name="218"><h3>218.&nbsp;Algorithms do not use binary predicate objects for default comparisons</h3></a><p><b>Section:</b>&nbsp;25.3 <a href="lib-algorithms.html#lib.alg.sorting"> [lib.alg.sorting]</a>&nbsp; <b>Status:</b>&nbsp;<a href="lwg-active.html#NAD">NAD</a>&nbsp; <b>Submitter:</b>&nbsp;Pablo Halpern&nbsp; <b>Date:</b>&nbsp;6 Mar 2000</p>
<p>Many of the algorithms take an argument, pred, of template parameter type
BinaryPredicate or an argument comp of template parameter type Compare. These
algorithms usually have an overloaded version that does not take the predicate
argument. In these cases pred is usually replaced by the use of operator== and
comp is replaced by the use of operator&lt;.</p>
<p>This use of hard-coded operators is inconsistent with other parts of the
library, particularly the containers library, where equality is established
using equal_to&lt;&gt; and ordering is established using less&lt;&gt;. Worse,
the use of operator&lt;, would cause the following innocent-looking code to have
undefined behavior:</p>
<blockquote>
  <pre>vector&lt;string*&gt; vec;
sort(vec.begin(), vec.end());</pre>
</blockquote>
<p>The use of operator&lt; is not defined for pointers to unrelated objects. If
std::sort used less&lt;&gt; to compare elements, then the above code would be
well-defined, since less&lt;&gt; is explicitly specialized to produce a total
ordering of pointers.</p>
<p><b>Proposed resolution:</b></p>
<p><b>Rationale:</b></p>
<p>This use of operator== and operator&lt; was a very deliberate, conscious, and
explicitly made design decision; these operators are often more efficient. The
predicate forms are available for users who don't want to rely on operator== and
operator&lt;.</p>
<hr>
<a name="219"><h3>219.&nbsp;find algorithm missing version that takes a binary predicate argument</h3></a><p><b>Section:</b>&nbsp;25.1.2 <a href="lib-algorithms.html#lib.alg.find"> [lib.alg.find]</a>&nbsp; <b>Status:</b>&nbsp;<a href="lwg-active.html#NAD">NAD</a>&nbsp;<a href="lwg-active.html#Future">Future</a>&nbsp; <b>Submitter:</b>&nbsp;Pablo Halpern&nbsp; <b>Date:</b>&nbsp;6 Mar 2000</p>
<p>The find function always searches for a value using operator== to compare the
value argument to each element in the input iterator range. This is inconsistent
with other find-related functions such as find_end and find_first_of, which
allow the caller to specify a binary predicate object to be used for determining
equality. The fact that this can be accomplished using a combination of find_if
and bind_1st or bind_2nd does not negate the desirability of a consistent,
simple, alternative interface to find.</p>
<p><b>Proposed resolution:</b></p>
<blockquote>
<p>In section 25.1.2 <a href="lib-algorithms.html#lib.alg.find"> [lib.alg.find]</a>, add a second prototype for find
(between the existing prototype and the prototype for find_if), as
follows:</p>
<pre>    template&lt;class InputIterator, class T, class BinaryPredicate&gt;
      InputIterator find(InputIterator first, InputIterator last,
                         const T&amp; value, BinaryPredicate bin_pred);</pre>
<p>Change the description of the return from:</p>
<blockquote>
  <p>Returns: The first iterator i in the range [first, last) for which the following corresponding
  conditions hold: *i == value, pred(*i) != false. Returns last if no such iterator is found.</p>
</blockquote>
<p>&nbsp;to:</p>
<blockquote>
  <p>Returns: The first iterator i in the range [first, last) for which the following&nbsp;
  corresponding condition holds: *i == value, bin_pred(*i,value) != false, pred(*)
  != false. Return last if no such iterator is found.</p>
</blockquote>
</blockquote>
<p><b>Rationale:</b></p>
<p>This is request for a pure extension, so it is not a defect in the
current standard.&nbsp; As the submitter pointed out, "this can
be accomplished using a combination of find_if and bind_1st or
bind_2nd".</p>
<hr>
<a name="236"><h3>236.&nbsp;ctype&lt;char&gt;::is() member modifies facet</h3></a><p><b>Section:</b>&nbsp;22.2.1.3.2 <a href="lib-locales.html#lib.facet.ctype.char.members"> [lib.facet.ctype.char.members]</a>&nbsp; <b>Status:</b>&nbsp;<a href="lwg-active.html#Dup">Dup</a>&nbsp; <b>Submitter:</b>&nbsp;Dietmar K&uuml;hl&nbsp; <b>Date:</b>&nbsp;24 Apr 2000</p>
<p>The description of the <tt>is()</tt> member in paragraph 4 of 22.2.1.3.2 <a href="lib-locales.html#lib.facet.ctype.char.members"> [lib.facet.ctype.char.members]</a> is broken: According to this description, the
second form of the <tt>is()</tt> method modifies the masks in the
<tt>ctype</tt> object. The correct semantics if, of course, to obtain
an array of masks. The corresponding method in the general case,
ie. the <tt>do_is()</tt> method as described in 22.2.1.1.2 <a href="lib-locales.html#lib.locale.ctype.virtuals"> [lib.locale.ctype.virtuals]</a> paragraph 1 does the right thing.</p>
<p><b>Proposed resolution:</b></p>
  <p>Change paragraph 4 from</p>
    <blockquote>
    The second form, for all *p in the range [low, high), assigns
    vec[p-low] to table()[(unsigned char)*p].
    </blockquote>
  <p>to become</p>
    <blockquote>
    The second form, for all *p in the range [low, high), assigns
    table()[(unsigned char)*p] to vec[p-low].
  </blockquote>
<p><b>Rationale:</b></p>
<p>Duplicate.  See issue <a href="lwg-defects.html#28">28</a>.</p>
<hr>
<a name="244"><h3>244.&nbsp;Must <tt>find</tt>'s third argument be CopyConstructible?</h3></a><p><b>Section:</b>&nbsp;25.1.2 <a href="lib-algorithms.html#lib.alg.find"> [lib.alg.find]</a>&nbsp; <b>Status:</b>&nbsp;<a href="lwg-active.html#NAD">NAD</a>&nbsp; <b>Submitter:</b>&nbsp;Andrew Koenig&nbsp; <b>Date:</b>&nbsp;02 May 2000</p>
<p>Is the following implementation of <tt>find</tt> acceptable?</p>

<pre>
        template&lt;class Iter, class X&gt;
        Iter find(Iter begin, Iter end, const X&amp; x)
        {
            X x1 = x;           // this is the crucial statement
            while (begin != end &amp;&amp; *begin != x1)
                ++begin;
            return begin;
        }
</pre>

<p>If the answer is yes, then it is implementation-dependent as to
whether the following fragment is well formed:</p>

<pre>
        vector&lt;string&gt; v;

        find(v.begin(), v.end(), "foo");
</pre>

<p>At issue is whether there is a requirement that the third argument
of find be CopyConstructible.  There may be no problem here, but
analysis is necessary.</p>
<p><b>Proposed resolution:</b></p>
<p><b>Rationale:</b></p>
<p>There is no indication in the standard that find's third argument
is required to be Copy Constructible.  The LWG believes that no such
requirement was intended.  As noted above, there are times when a user
might reasonably pass an argument that is not Copy Constructible.</p>
<hr>
<a name="245"><h3>245.&nbsp;Which operations on <tt>istream_iterator</tt> trigger input operations?</h3></a><p><b>Section:</b>&nbsp;24.5.1 <a href="lib-iterators.html#lib.istream.iterator"> [lib.istream.iterator]</a>&nbsp; <b>Status:</b>&nbsp;<a href="lwg-active.html#NAD">NAD</a>&nbsp; <b>Submitter:</b>&nbsp;Andrew Koenig&nbsp; <b>Date:</b>&nbsp;02 May 2000</p>
<p>I do not think the standard specifies what operation(s) on istream
iterators trigger input operations.  So, for example:</p>

<pre>
        istream_iterator&lt;int&gt; i(cin);

        int n = *i++;
</pre>

<p>I do not think it is specified how many integers have been read
from cin.  The number must be at least 1, of course, but can it be 2?
More?</p>
<p><b>Proposed resolution:</b></p>
<p><b>Rationale:</b></p>
<p>The standard is clear as written: the stream is read every time
operator++ is called, and it is also read either when the iterator is
constructed or when operator* is called for the first time.  In the
example above, exactly two integers are read from cin.</p>

<p>There may be a problem with the interaction between istream_iterator
and some STL algorithms, such as find.  There are no guarantees about
how many times find may invoke operator++.</p>
<hr>
<a name="246"><h3>246.&nbsp;<tt>a.insert(p,t)</tt> is incorrectly specified</h3></a><p><b>Section:</b>&nbsp;23.1.2 <a href="lib-containers.html#lib.associative.reqmts"> [lib.associative.reqmts]</a>&nbsp; <b>Status:</b>&nbsp;<a href="lwg-active.html#Dup">Dup</a>&nbsp; <b>Submitter:</b>&nbsp;Mark Rodgers&nbsp; <b>Date:</b>&nbsp;19 May 2000</p>
<p>Closed issue 192 raised several problems with the specification of
this function, but was rejected as Not A Defect because it was too big
a change with unacceptable impacts on existing implementations.
However, issues remain that could be addressed with a smaller change
and with little or no consequent impact.</p>

<ol>
   <li>
<p> The specification is inconsistent with the original
   proposal and with several implementations.</p>

   <p>The initial implementation by Hewlett Packard only ever looked
   immediately <i>before</i> p, and I do not believe there was any
   intention to standardize anything other than this behavior.
   Consequently, current implementations by several leading
   implementors also look immediately before p, and will only insert
   after p in logarithmic time.  I am only aware of one implementation
   that does actually look after p, and it looks before p as well.  It
   is therefore doubtful that existing code would be relying on the
   behavior defined in the standard, and it would seem that fixing
   this defect as proposed below would standardize existing
   practice.</p>
</li>

   <li>
<p>
   The specification is inconsistent with insertion for sequence
   containers.</p>

   <p>This is difficult and confusing to teach to newcomers.  All
   insert operations that specify an iterator as an insertion location
   should have a consistent meaning for the location represented by
   that iterator.</p>
</li>

   <li>
<p> As specified, there is no way to hint that the insertion
   should occur at the beginning of the container, and the way to hint
   that it should occur at the end is long winded and unnatural.</p>

   <p>For a container containing n elements, there are n+1 possible
   insertion locations and n+1 valid iterators.  For there to be a
   one-to-one mapping between iterators and insertion locations, the
   iterator must represent an insertion location immediately before
   the iterator.</p>
</li>

   <li>
<p> When appending sorted ranges using insert_iterators,
   insertions are guaranteed to be sub-optimal.</p>

   <p>In such a situation, the optimum location for insertion is
   always immediately after the element previously inserted.  The
   mechanics of the insert iterator guarantee that it will try and
   insert after the element after that, which will never be correct.
   However, if the container first tried to insert before the hint,
   all insertions would be performed in amortized constant
   time.</p>
</li>
</ol>
<p><b>Proposed resolution:</b></p>
<p>In 23.1.2 [lib.associative.reqmts] paragraph 7, table 69, make
the following changes in the row for a.insert(p,t):</p>

<p><i>assertion/note pre/post condition:</i>
<br>Change the last sentence from</p>
     <blockquote>
     "iterator p is a hint pointing to where the insert should
     start to search."
     </blockquote>
<p>to</p>
     <blockquote>
     "iterator p is a hint indicating that immediately before p
     may be a correct location where the insertion could occur."
     </blockquote>

<p><i>complexity:</i><br>
Change the words "right after" to "immediately before".</p>
<p><b>Rationale:</b></p>
<p>Duplicate; see issue <a href="lwg-active.html#233">233</a>.</p>
<hr>
<a name="249"><h3>249.&nbsp;Return Type of <tt>auto_ptr::operator=</tt>
</h3></a><p><b>Section:</b>&nbsp;20.4.5 <a href="lib-utilities.html#lib.auto.ptr"> [lib.auto.ptr]</a>&nbsp; <b>Status:</b>&nbsp;<a href="lwg-active.html#NAD">NAD</a>&nbsp; <b>Submitter:</b>&nbsp;Joseph Gottman&nbsp; <b>Date:</b>&nbsp;30 Jun 2000</p>
<p>According to section 20.4.5, the function
<tt>auto_ptr::operator=()</tt> returns a reference to an auto_ptr.
The reason that <tt>operator=()</tt> usually returns a reference is to
facilitate code like</p>

<pre>
    int x,y,z;
    x = y = z = 1;
</pre>

<p>However, given analogous code for <tt>auto_ptr</tt>s,</p>
<pre>
    auto_ptr&lt;int&gt; x, y, z;
    z.reset(new int(1));
    x = y = z;
</pre>

<p>the result would be that <tt>z</tt> and <tt>y</tt> would both be set to 
NULL, instead of all the <tt>auto_ptr</tt>s being set to the same value. 
This makes such cascading assignments useless and counterintuitive for 
<tt>auto_ptr</tt>s.</p>
<p><b>Proposed resolution:</b></p>
<p>Change <tt>auto_ptr::operator=()</tt> to return <tt>void</tt> instead
of an <tt>auto_ptr</tt> reference.</p>
<p><b>Rationale:</b></p>
<p>The return value has uses other than cascaded assignments: a user can
call an auto_ptr member function, pass the auto_ptr to a
function, etc.  Removing the return value could break working user
code.</p>
<hr>
<a name="255"><h3>255.&nbsp;Why do <tt>basic_streambuf&lt;&gt;::pbump()</tt> and <tt>gbump()</tt> take an int?</h3></a><p><b>Section:</b>&nbsp;27.5.2 <a href="lib-iostreams.html#lib.streambuf"> [lib.streambuf]</a>&nbsp; <b>Status:</b>&nbsp;<a href="lwg-active.html#NAD">NAD</a>&nbsp;<a href="lwg-active.html#Future">Future</a>&nbsp; <b>Submitter:</b>&nbsp;Martin Sebor&nbsp; <b>Date:</b>&nbsp;12 Aug 2000</p>
<p>
The basic_streambuf members gbump() and pbump() are specified to take an
int argument. This requirement prevents the functions from effectively
manipulating buffers larger than std::numeric_limits&lt;int&gt;::max()
characters. It also makes the common use case for these functions
somewhat difficult as many compilers will issue a warning when an
argument of type larger than int (such as ptrdiff_t on LLP64
architectures) is passed to either of the function. Since it's often the
result of the subtraction of two pointers that is passed to the
functions, a cast is necessary to silence such warnings. Finally, the
usage of a native type in the functions signatures is inconsistent with
other member functions (such as sgetn() and sputn()) that manipulate the
underlying character buffer. Those functions take a streamsize argument.
</p>
<p><b>Proposed resolution:</b></p>
<p>
Change the signatures of these functions in the synopsis of template
class basic_streambuf (27.5.2) and in their descriptions (27.5.2.3.1, p4
and 27.5.2.3.2, p4) to take a streamsize argument.
</p>

<p>
Although this change has the potential of changing the ABI of the
library, the change will affect only platforms where int is different
than the definition of streamsize. However, since both functions are
typically inline (they are on all known implementations), even on such
platforms the change will not affect any user code unless it explicitly
relies on the existing type of the functions (e.g., by taking their
address). Such a possibility is IMO quite remote.
</p>

<p>
Alternate Suggestion from Howard Hinnant, c++std-lib-7780:
</p>

<p>
This is something of a nit, but I'm wondering if streamoff wouldn't be a 
better choice than streamsize.  The argument to pbump and gbump MUST be 
signed.  But the standard has this to say about streamsize 
(27.4.1/2/Footnote):
</p>

<blockquote>
     [Footnote: streamsize is used in most places where ISO C would use
     size_t.  Most of the uses of streamsize could use size_t, except for
     the strstreambuf constructors, which require negative values. It
     should probably be the signed type corresponding to size_t (which is
     what Posix.2 calls ssize_t). --- end footnote]
</blockquote>

<p>
This seems a little weak for the argument to pbump and gbump.  Should we 
ever really get rid of strstream, this footnote might go with it, along 
with the reason to make streamsize signed.
</p>
<p><b>Rationale:</b></p>
<p>The LWG believes this change is too big for now.  We may wish to
reconsider this for a future revision of the standard.  One
possibility is overloading pbump, rather than changing the
signature.</p>
<hr>
<a name="257"><h3>257.&nbsp;STL functional object and iterator inheritance.</h3></a><p><b>Section:</b>&nbsp;20.3.1 <a href="lib-utilities.html#lib.base"> [lib.base]</a>, 24.3.2 <a href="lib-iterators.html#lib.iterator.basic"> [lib.iterator.basic]</a>&nbsp; <b>Status:</b>&nbsp;<a href="lwg-active.html#NAD">NAD</a>&nbsp; <b>Submitter:</b>&nbsp;Robert Dick &nbsp; <b>Date:</b>&nbsp;17 Aug 2000</p>
<p>
According to the November 1997 Draft Standard, the results of deleting an
object of a derived class through a pointer to an object of its base class are
undefined if the base class has a non-virtual destructor.  Therefore, it is
potentially dangerous to publicly inherit from such base classes.
</p>

<p>Defect:
<br>
The STL design encourages users to publicly inherit from a number of classes
which do nothing but specify interfaces, and which contain non-virtual
destructors.
</p>

<p>Attribution:
<br>
Wil Evers and William E. Kempf suggested this modification for functional
objects.
</p>
<p><b>Proposed resolution:</b></p>
<p>
When a base class in the standard library is useful only as an interface
specifier, i.e., when an object of the class will never be directly
instantiated, specify that the class contains a protected destructor.  This
will prevent deletion through a pointer to the base class without performance,
or space penalties (on any implementation I'm aware of).
</p>

<p>
As an example, replace...
</p>

<pre>
    template &lt;class Arg, class Result&gt;
    struct unary_function {
            typedef Arg    argument_type;
            typedef Result result_type;
    };
</pre>

<p>
... with...
</p>

<pre>
    template &lt;class Arg, class Result&gt;
    struct unary_function {
            typedef Arg    argument_type;
            typedef Result result_type;
    protected:
            ~unary_function() {}
    };
</pre>

<p>
Affected definitions:
<br>
  &nbsp;20.3.1 [lib.function.objects] -- unary_function, binary_function
  <br>
  &nbsp;24.3.2 [lib.iterator.basic] -- iterator
</p>
<p><b>Rationale:</b></p>
<p>
The standard is clear as written; this is a request for change, not a
defect in the strict sense.  The LWG had several different objections
to the proposed change.  One is that it would prevent users from
creating objects of type <tt>unary_function</tt> and
<tt>binary_function</tt>.  Doing so can sometimes be legitimate, if users
want to pass temporaries as traits or tag types in generic code.
</p>
<hr>
<a name="267"><h3>267.&nbsp;interaction of strstreambuf::overflow() and seekoff()</h3></a><p><b>Section:</b>&nbsp;D.7.1.3 <a href="future.html#depr.strstreambuf.virtuals"> [depr.strstreambuf.virtuals]</a>&nbsp; <b>Status:</b>&nbsp;<a href="lwg-active.html#NAD">NAD</a>&nbsp; <b>Submitter:</b>&nbsp;Martin Sebor&nbsp; <b>Date:</b>&nbsp;5 Oct 2000</p>
<p>
It appears that the interaction of the strstreambuf members overflow()
and seekoff() can lead to undefined behavior in cases where defined
behavior could reasonably be expected. The following program
demonstrates this behavior:
</p>

<pre>
    #include &lt;strstream&gt;

    int main ()
    {
         std::strstreambuf sb;
         sb.sputc ('c');

         sb.pubseekoff (-1, std::ios::end, std::ios::in);
         return !('c' == sb.sgetc ());
    }
</pre>

<p>
D.7.1.1, p1 initializes strstreambuf with a call to basic_streambuf&lt;&gt;(),
which in turn sets all pointers to 0 in 27.5.2.1, p1.
</p>
 
<p>
27.5.2.2.5, p1 says that basic_streambuf&lt;&gt;::sputc(c) calls
overflow(traits::to_int_type(c)) if a write position isn't available (it
isn't due to the above).
</p>

<p>
D.7.1.3, p3 says that strstreambuf::overflow(off, ..., ios::in) makes at
least one write position available (i.e., it allows the function to make
any positive number of write positions available).
</p>

<p>
D.7.1.3, p13 computes newoff = seekhigh - eback(). In D.7.1, p4 we see
seekhigh = epptr() ? epptr() : egptr(), or seekhigh = epptr() in this
case. newoff is then epptr() - eback().
</p>

<p>
D.7.1.4, p14 sets gptr() so that gptr() == eback() + newoff + off, or
gptr() == epptr() + off holds.
</p>

<p>
If strstreambuf::overflow() made exactly one write position available
then gptr() will be set to just before epptr(), and the program will
return 0. Buf if the function made more than one write position
available, epptr() and gptr() will both point past pptr() and the
behavior of the program is undefined.
</p>
<p><b>Proposed resolution:</b></p>


   <p>Change the last sentence of D.7.1 <a href="future.html#depr.strstreambuf"> [depr.strstreambuf]</a> paragraph 4 from</p>

      <blockquote>
      Otherwise, seeklow equals gbeg and seekhigh is either pend, if
      pend is not a null pointer, or gend.
      </blockquote>

   <p>to become</p>

      <blockquote>
      Otherwise, seeklow equals gbeg and seekhigh is either gend if
      0 == pptr(), or pbase() + max where max is the maximum value of
      pptr() - pbase() ever reached for this stream.
      </blockquote>

<p><i>[
  pre-Copenhagen: Dietmar provided wording for proposed resolution.
]</i></p>

<p><i>[
  post-Copenhagen: Fixed a typo: proposed resolution said to fix
  4.7.1, not D.7.1.
]</i></p>

<p><b>Rationale:</b></p>
<p>This is related to issue <a href="lwg-closed.html#65">65</a>: it's not clear what it
means to seek beyond the current area.  Without resolving issue <a href="lwg-closed.html#65">65</a> we can't resolve this.  As with issue <a href="lwg-closed.html#65">65</a>, 
the library working group does not wish to invest time nailing down
corner cases in a deprecated feature.</p>
<hr>
<a name="269"><h3>269.&nbsp;cstdarg and unnamed parameters</h3></a><p><b>Section:</b>&nbsp;18.7 <a href="lib-support.html#lib.support.runtime"> [lib.support.runtime]</a>&nbsp; <b>Status:</b>&nbsp;<a href="lwg-active.html#NAD">NAD</a>&nbsp; <b>Submitter:</b>&nbsp;J. Stephen Adamczyk&nbsp; <b>Date:</b>&nbsp;10 Oct 2000</p>
<p>
One of our customers asks whether this is valid C++:
</p>

<pre>
   #include &lt;cstdarg&gt;

   void bar(const char *, va_list);

   void
   foo(const char *file, const char *, ...)
   {
     va_list ap;
     va_start(ap, file);
     bar(file, ap);
     va_end(ap);
   }
</pre>

<p>
The issue being whether it is valid to use cstdarg when the final
parameter before the "..." is unnamed.  cstdarg is, as far
as I can tell, inherited verbatim from the C standard. and the
definition there (7.8.1.1 in the ISO C89 standard) refers to "the
identifier of the rightmost parameter".  What happens when there
is no such identifier?
</p>

<p>
My personal opinion is that this should be allowed, but some tweak
might be required in the C++ standard.
</p>
<p><b>Proposed resolution:</b></p>
<p><b>Rationale:</b></p>
<p>
Not a defect, the C and C++ standards are clear.  It is impossible to
use varargs if the parameter immediately before "..." has no
name, because that is the parameter that must be passed to va_start.
The example given above is broken, because va_start is being passed
the wrong parameter.
</p>

<p>
There is no support for extending varargs to provide additional
functionality beyond what's currently there.  For reasons of C/C++
compatibility, it is especially important not to make gratuitous
changes in this part of the C++ standard.  The C committee has already
been requested not to touch this part of the C standard unless
necessary.
</p>
<hr>
<a name="277"><h3>277.&nbsp;Normative encouragement in allocator requirements unclear</h3></a><p><b>Section:</b>&nbsp;20.1.5 <a href="lib-utilities.html#lib.allocator.requirements"> [lib.allocator.requirements]</a>&nbsp; <b>Status:</b>&nbsp;<a href="lwg-active.html#NAD">NAD</a>&nbsp; <b>Submitter:</b>&nbsp;Matt Austern&nbsp; <b>Date:</b>&nbsp;07 Nov 2000</p>
<p>
In 20.1.5, paragraph 5, the standard says that "Implementors are
encouraged to supply libraries that can accept allocators that
encapsulate more general memory models and that support non-equal
instances." This is intended as normative encouragement to
standard library implementors.  However, it is possible to interpret
this sentence as applying to nonstandard third-party libraries.
</p>
<p><b>Proposed resolution:</b></p>
<p>
In 20.1.5, paragraph 5, change "Implementors" to
"Implementors of the library described in this International
Standard".
</p>
<p><b>Rationale:</b></p>
<p>The LWG believes the normative encouragement is already
sufficiently clear, and that there are no important consequences
even if it is misunderstood.</p>
<hr>
<a name="279"><h3>279.&nbsp;const and non-const iterators should have equivalent typedefs</h3></a><p><b>Section:</b>&nbsp;23.1 <a href="lib-containers.html#lib.container.requirements"> [lib.container.requirements]</a>&nbsp; <b>Status:</b>&nbsp;<a href="lwg-active.html#NAD">NAD</a>&nbsp; <b>Submitter:</b>&nbsp;Steve Cleary&nbsp; <b>Date:</b>&nbsp;27 Nov 2000</p>

<p>
This came from an email from Steve Cleary to Fergus in reference to
issue <a href="lwg-defects.html#179">179</a>. The library working group briefly discussed
this in Toronto and believes it should be a separate issue.
</p>

<p>
Steve said: "We may want to state that the const/non-const iterators must have
the same difference type, size_type, and category."
</p>

<p>
(Comment from Judy)
I'm not sure if the above sentence should be true for all
const and non-const iterators in a particular container, or if it means 
the container's iterator can't be compared with the container's
const_iterator unless the above it true. I suspect the former.
</p>
<p><b>Proposed resolution:</b></p>
<p>
In <b>Section:</b> 23.1 <a href="lib-containers.html#lib.container.requirements"> [lib.container.requirements]</a>,
table 65, in the assertion/note pre/post condition for X::const_iterator,
add the following:
</p>

<blockquote>
<p>
typeid(X::const_iterator::difference_type) == typeid(X::iterator::difference_type)
</p>

<p>
typeid(X::const_iterator::size_type) == typeid(X::iterator::size_type)
</p>

<p>
typeid(X::const_iterator::category) == typeid(X::iterator::category)
</p>
</blockquote>
<p><b>Rationale:</b></p>
<p>Going through the types one by one: Iterators don't have a
<tt>size_type</tt>.  We already know that the difference types are
identical, because the container requirements already say that the
difference types of both X::iterator and X::const_iterator are both
X::difference_type.  The standard does not require that X::iterator
and X::const_iterator have the same iterator category, but the LWG
does not see this as a defect: it's possible to imagine cases in which
it would be useful for the categories to be different.</p>

<p>It may be desirable to require X::iterator and X::const_iterator to
have the same value type, but that is a new issue. (Issue <a href="lwg-defects.html#322">322</a>.)</p>

<hr>
<a name="287"><h3>287.&nbsp;conflicting ios_base fmtflags</h3></a><p><b>Section:</b>&nbsp;27.4.2.2 <a href="lib-iostreams.html#lib.fmtflags.state"> [lib.fmtflags.state]</a>&nbsp; <b>Status:</b>&nbsp;<a href="lwg-active.html#NAD">NAD</a>&nbsp; <b>Submitter:</b>&nbsp;Judy Ward&nbsp; <b>Date:</b>&nbsp;30 Dec 2000</p>
<p>
The Effects clause for ios_base::setf(fmtflags fmtfl) says
"Sets fmtfl in flags()".  What happens if the user first calls
ios_base::scientific and then calls ios_base::fixed or vice-versa?
This is an issue for all of the conflicting flags, i.e. ios_base::left
and ios_base::right or ios_base::dec, ios_base::hex and ios_base::oct.
</p>

<p>
I see three possible solutions: 
</p>

<ol>
<li>Set ios_base::failbit whenever the user specifies a conflicting
flag with one previously explicitly set. If the constructor is
supposed to set ios_base::dec (see discussion below), then
the user setting hex or oct format after construction will not
set failbit. </li>
<li>The last call to setf "wins", i.e. it clears any conflicting
previous setting.</li>
<li>All the flags that the user specifies are set, but when actually 
interpreting them, fixed always override scientific, right always 
overrides left, dec overrides hex which overrides oct.</li>
</ol>

<p>
Most existing implementations that I tried seem to conform to resolution #3,
except that when using the iomanip manipulator hex or oct then that always 
overrides dec, but calling setf(ios_base::hex) doesn't. 
</p>

<p>
There is a sort of related issue, which is that although the ios_base
constructor says that each ios_base member has an indeterminate value
after construction, all the existing implementations I tried explicitly set 
ios_base::dec.
</p>
<p><b>Proposed resolution:</b></p>
<p><b>Rationale:</b></p>
<p>
<tt>adjustfield</tt>, <tt>basefield</tt>, and <tt>floatfield</tt>
are each multi-bit fields.  It is possible to set multiple bits within
each of those fields.  (For example, <tt>dec</tt> and
<tt>oct</tt>). These fields are used by locale facets.  The LWG
reviewed the way in which each of those three fields is used, and
believes that in each case the behavior is well defined for any
possible combination of bits.  See for example Table 58, in 22.2.2.2.2 <a href="lib-locales.html#lib.facet.num.put.virtuals"> [lib.facet.num.put.virtuals]</a>, noting the requirement in paragraph 6 of that
section.
</p>
<p>
Users are advised to use manipulators, or else use the two-argument
version of <tt>setf</tt>, to avoid unexpected behavior.
</p>
<hr>
<a name="289"><h3>289.&nbsp;&lt;cmath&gt; requirements missing C float and long double versions</h3></a><p><b>Section:</b>&nbsp;26.5 <a href="lib-numerics.html#lib.c.math"> [lib.c.math]</a>&nbsp; <b>Status:</b>&nbsp;<a href="lwg-active.html#NAD">NAD</a>&nbsp; <b>Submitter:</b>&nbsp;Judy Ward&nbsp; <b>Date:</b>&nbsp;30 Dec 2000</p>
<p>
    In ISO/IEC 9899:1990 Programming Languages C we find the following
    concerning &lt;math.h&gt;:
</p>

<blockquote>
         7.13.4 Mathematics &lt;math.h&gt;
         <br>
         The names of all existing functions declared in the &lt;math.h&gt;
         header, suffixed with f or l, are reserved respectively for
         corresponding functions with float and long double arguments
         are return values.
</blockquote>

<p>
    For example, <tt>float&nbsp;sinf(float)</tt>
    is reserved.
</p>

<p>
    In the C99 standard, &lt;math.h&gt; must contain declarations
    for these functions.
</p>

<p>
So, is it acceptable for an implementor to add these prototypes to the
C++ versions of the math headers? Are they required?
</p>
<p><b>Proposed resolution:</b></p>
<p>
Add these Functions to Table 80, section 26.5 and to Table 99,
section C.2:
</p>

<pre>
    acosf asinf atanf atan2f ceilf cosf coshf 
    expf fabsf floorf fmodf frexpf ldexpf 
    logf log10f modff powf sinf sinhf sqrtf 
    tanf tanhf 
    acosl asinl atanl atan2l ceill cosl coshl 
    expl fabsl floorl fmodl frexpl ldexpl 
    logl log10l modfl powl sinl sinhl sqrtl 
    tanl tanhl
</pre>

<p>
There should probably be a note saying that these functions
are optional and, if supplied, should match the description in
the 1999 version of the C standard. In the next round
of C++ standardization they can then become mandatory. 
</p>
<p><b>Rationale:</b></p>
<p>The C90 standard, as amended, already permits (but does not
require) these functions, and the C++ standard incorporates the
C90 standard by reference.  C99 is not an issue, because it is
never referred to by the C++ standard.</p>
<hr>
<a name="293"><h3>293.&nbsp;Order of execution in transform algorithm</h3></a><p><b>Section:</b>&nbsp;25.2.3 <a href="lib-algorithms.html#lib.alg.transform"> [lib.alg.transform]</a>&nbsp; <b>Status:</b>&nbsp;<a href="lwg-active.html#NAD">NAD</a>&nbsp; <b>Submitter:</b>&nbsp;Angelika Langer&nbsp; <b>Date:</b>&nbsp;04 Jan 2001</p>
<p>This issue is related to issue 242.  In case that the resolution
proposed for issue 242 is accepted, we have have the following
situation: The 4 numeric algorithms (accumulate and consorts) as well
as transform would allow a certain category of side effects.  The
numeric algorithms specify that they invoke the functor "for
every iterator i in the range [first, last) in order". transform,
in contrast, would not give any guarantee regarding order of
invocation of the functor, which means that the functor can be invoked
in any arbitrary order.
</p>

<p>Why would that be a problem?  Consider an example: say the
transformator that is a simple enumerator ( or more generally
speaking, "is order-sensitive" ).  Since a standard
compliant implementation of transform is free to invoke the enumerator
in no definite order, the result could be a garbled enumeration.
Strictly speaking this is not a problem, but it is certainly at odds
with the prevalent understanding of transform as an algorithms that
assigns "a new _corresponding_ value" to the output
elements.
</p>

<p>All implementations that I know of invoke the transformator in
definite order, namely starting from first and proceeding to last -
1. Unless there is an optimization conceivable that takes advantage of
the indefinite order I would suggest to specify the order, because it
eliminate the uncertainty that users would otherwise have regarding
the order of execution of their potentially order-sensitive function
objects.
</p>
<p><b>Proposed resolution:</b></p>
<p>In section 25.2.3 - Transform [lib.alg.transform] change:</p>
<blockquote>
-1- Effects: Assigns through every iterator i in the range [result,
result + (last1 - first1)) a new corresponding
value equal to op(*(first1 + (i - result)) or binary_op(*(first1 +
(i - result), *(first2 + (i - result))).
</blockquote>
<p>to:</p>
<blockquote>
-1- Effects: Computes values by  invoking the operation op or binary_op 
for every iterator in the range [first1, last1) in order. Assigns through
every iterator i in the range [result, result + (last1 - first1)) a new
corresponding
value equal to op(*(first1 + (i - result)) or binary_op(*(first1 +
(i - result), *(first2 + (i - result))).
</blockquote>
<p><b>Rationale:</b></p>
<p>For Input Iterators an order is already guaranteed, because
only one order is possible.  If a user who passes a Forward
Iterator to one of these algorithms really needs a specific
order of execution, it's possible to achieve that effect by
wrapping it in an Input Iterator adaptor.</p>
<hr>
<a name="296"><h3>296.&nbsp;Missing descriptions and requirements of pair operators</h3></a><p><b>Section:</b>&nbsp;20.2.2 <a href="lib-utilities.html#lib.pairs"> [lib.pairs]</a>&nbsp; <b>Status:</b>&nbsp;<a href="lwg-active.html#NAD">NAD</a>&nbsp; <b>Submitter:</b>&nbsp;Martin Sebor&nbsp; <b>Date:</b>&nbsp;14 Jan 2001</p>
<p>The synopsis of the header <tt>&lt;utility&gt;</tt> in 20.2 <a href="lib-utilities.html#lib.utility"> [lib.utility]</a>
lists the complete set of equality and relational operators for <tt>pair</tt>
but the section describing the template and the operators only describes
<tt>operator==()</tt> and <tt>operator&lt;()</tt>, and it fails to mention
any requirements on the template arguments. The remaining operators are
not mentioned at all.
</p> 
<p><b>Proposed resolution:</b></p>
<p><b>Rationale:</b></p>
<p>20.2.1 <a href="lib-utilities.html#lib.operators"> [lib.operators]</a> paragraph 10 already specifies the semantics.
That paragraph says that, if declarations of operator!=, operator&gt;,
operator&lt;=, and operator&gt;= appear without definitions, they are
defined as specified in 20.2.1 <a href="lib-utilities.html#lib.operators"> [lib.operators]</a>.  There should be no user
confusion, since that paragraph happens to immediately precede the
specification of <tt>pair</tt>.</p>
<hr>
<a name="302"><h3>302.&nbsp;Need error indication from codecvt&lt;&gt;::do_length</h3></a><p><b>Section:</b>&nbsp;22.2.1.5.2 <a href="lib-locales.html#lib.locale.codecvt.virtuals"> [lib.locale.codecvt.virtuals]</a>&nbsp; <b>Status:</b>&nbsp;<a href="lwg-active.html#NAD">NAD</a>&nbsp; <b>Submitter:</b>&nbsp;Gregory Bumgardner&nbsp; <b>Date:</b>&nbsp;25 Jan 2001</p>
<p>
The effects of <tt>codecvt&lt;&gt;::do_length()</tt> are described in
22.2.1.5.2, paragraph 10.  As implied by that paragraph, and clarified
in issue <a href="lwg-defects.html#75">75</a>, <tt>codecvt&lt;&gt;::do_length()</tt> must
process the source data and update the <tt>stateT</tt> argument just
as if the data had been processed by <tt>codecvt&lt;&gt;::in()</tt>.
However, the standard does not specify how <tt>do_length()</tt> would
report a translation failure, should the source sequence contain
untranslatable or illegal character sequences.
</p>

<p>
The other conversion methods return an "error" result value
to indicate that an untranslatable character has been encountered, but
<tt>do_length()</tt> already has a return value (the number of source
characters that have been processed by the method).
</p>
<p><b>Proposed resolution:</b></p>
<p>
This issue cannot be resolved without modifying the interface. An exception
cannot be used, as there would be no way to determine how many characters
have been processed and the state object would be left in an indeterminate
state.
</p>

<p>
A source compatible solution involves adding a fifth argument to length()
and do_length() that could be used to return position of the offending
character sequence. This argument would have a default value that would
allow it to be ignored:
</p>

<pre>
  int length(stateT&amp; state, 
             const externT* from, 
             const externT* from_end, 
             size_t max,
             const externT** from_next = 0);

  virtual
  int do_length(stateT&amp; state, 
                const externT* from, 
                const externT* from_end, 
                size_t max,
                const externT** from_next);
</pre>

<p>
Then an exception could be used to report any translation errors and
the from_next argument, if used, could then be used to retrieve the
location of the offending character sequence.
</p>
<p><b>Rationale:</b></p>
<p>The standard is already clear: the return value is the number of
"valid complete characters".  If it encounters an invalid sequence of
external characters, it stops.</p>
<hr>
<a name="304"><h3>304.&nbsp;Must <tt>*a</tt> return an lvalue when <tt>a</tt> is an input iterator?</h3></a><p><b>Section:</b>&nbsp;24.1 <a href="lib-iterators.html#lib.iterator.requirements"> [lib.iterator.requirements]</a>&nbsp; <b>Status:</b>&nbsp;<a href="lwg-active.html#NAD">NAD</a>&nbsp; <b>Submitter:</b>&nbsp;Dave Abrahams&nbsp; <b>Date:</b>&nbsp;5 Feb 2001</p>
<p>
We all "know" that input iterators are allowed to produce
values when dereferenced of which there is no other in-memory copy.
</p>

<p>
But: Table 72, with a careful reading, seems to imply that this can only be
the case if the value_type has no members (e.g. is a built-in type).
</p>

<p>The problem occurs in the following entry:</p>

<pre>
  a-&gt;m     pre: (*a).m is well-defined
           Equivalent to (*a).m
</pre>

<p>
<tt>*a.m</tt> can be well-defined if <tt>*a</tt> is not a reference
type, but since <tt>operator-&gt;()</tt> must return a pointer for
<tt>a-&gt;m</tt> to be well-formed, it needs something to return a
pointer <i>to</i>. This seems to indicate that <tt>*a</tt> must be
buffered somewhere to make a legal input iterator.
</p>

<p>I don't think this was intentional.</p>
<p><b>Proposed resolution:</b></p>
<p><b>Rationale:</b></p>
<p>The current standard is clear and consistent.  Input iterators that
  return rvalues are in fact implementable.  They may in some cases
  require extra work, but it is still possible to define an operator-&gt;
  in such cases: it doesn't have to return a T*, but may return a
  proxy type.  No change to the standard is justified.</p>
<hr>
<a name="313"><h3>313.&nbsp;set_terminate and set_unexpected question</h3></a><p><b>Section:</b>&nbsp;18.6.3.3 <a href="lib-support.html#lib.terminate"> [lib.terminate]</a>&nbsp; <b>Status:</b>&nbsp;<a href="lwg-active.html#NAD">NAD</a>&nbsp; <b>Submitter:</b>&nbsp;Judy Ward&nbsp; <b>Date:</b>&nbsp;3 Apr 2001</p>
<p>
According to section 18.6.3.3 of the standard, std::terminate() is
supposed to call the terminate_handler in effect immediately after
evaluating the throw expression.
</p>

<p>
Question: what if the terminate_handler in effect is itself
std::terminate?
</p>

<p>For example:</p>

<pre>
  #include &lt;exception&gt;

  int main () {
      std::set_terminate(std::terminate);
      throw 5;
      return 0;
  }
</pre>

<p>
Is the implementation allowed to go into an infinite loop?
</p>

<p>
I think the same issue applies to std::set_unexpected.
</p>
<p><b>Proposed resolution:</b></p>
<p><b>Rationale:</b></p>
<p>Infinite recursion is to be expected: users who set the terminate
handler to <tt>terminate</tt> are explicitly asking for <tt>terminate</tt>
to call itself.</p>
<hr>
<a name="314"><h3>314.&nbsp;Is the stack unwound when terminate() is called?</h3></a><p><b>Section:</b>&nbsp;18.6.3.3 <a href="lib-support.html#lib.terminate"> [lib.terminate]</a>&nbsp; <b>Status:</b>&nbsp;<a href="lwg-active.html#NAD">NAD</a>&nbsp; <b>Submitter:</b>&nbsp;Detlef Vollmann&nbsp; <b>Date:</b>&nbsp;11 Apr 2001</p>

<p>
The standard appears to contradict itself about whether the stack is
unwound when the implementation calls terminate().
</p>

<p>From 18.6.3.3p2:</p>
<blockquote>
    Calls the terminate_handler function in effect immediately
    after evaluating the throw-expression (lib.terminate.handler),
    if called by the implementation [...]
</blockquote>

<p>So the stack is guaranteed not to be unwound.</p>

<p>But from 15.3p9:</p>
<blockquote>
    [...]whether or not the stack is unwound before this call
    to terminate() is implementation-defined (except.terminate).
</blockquote>

<p>
And 15.5.1 actually defines that in most cases the stack is unwound.
</p>
<p><b>Proposed resolution:</b></p>
<p><b>Rationale:</b></p>
<p>There is definitely no contradiction between the core and library
clauses; nothing in the core clauses says that stack unwinding happens
after <tt>terminate</tt> is called.  18.6.3.3p2 does not say anything
about when terminate() is called; it merely specifies which
<tt>terminate_handler</tt> is used.</p>
<hr>
<a name="323"><h3>323.&nbsp;abs() overloads in different headers</h3></a><p><b>Section:</b>&nbsp;26.5 <a href="lib-numerics.html#lib.c.math"> [lib.c.math]</a>&nbsp; <b>Status:</b>&nbsp;<a href="lwg-active.html#NAD">NAD</a>&nbsp;<a href="lwg-active.html#Future">Future</a>&nbsp; <b>Submitter:</b>&nbsp;Dave Abrahams&nbsp; <b>Date:</b>&nbsp;4 June 2001</p>
<p>Currently the standard mandates the following overloads of
abs():</p>

<pre>
    abs(long), abs(int) in &lt;cstdlib&gt;

    abs(float), abs(double), abs(long double) in &lt;cmath&gt;

    template&lt;class T&gt; T abs(const complex&lt;T&gt;&amp;) in &lt;complex&gt;

    template&lt;class T&gt; valarray&lt;T&gt; abs(const valarray&lt;T&gt;&amp;); in &lt;valarray&gt;
</pre>

<p>
The problem is that having only some overloads visible of a function
that works on "implicitly inter-convertible" types is dangerous in
practice. The headers that get included at any point in a translation
unit can change unpredictably during program
development/maintenance. The wrong overload might be unintentionally
selected.
</p>

<p>
Currently, there is nothing that mandates the simultaneous visibility
of these overloads. Indeed, some vendors have begun fastidiously
reducing dependencies among their (public) headers as a QOI issue: it
helps people to write portable code by refusing to compile unless all
the correct headers are #included.
</p>

<p>The same issue may exist for other functions in the library.</p>

<p>Redmond: PJP reports that C99 adds two new kinds of abs: complex,
and int_max_abs.</p>

<p>Related issue: <a href="lwg-closed.html#343">343</a>.</p>

<p><b>Proposed resolution:</b></p>
<p><b>Rationale:</b></p>
<p>The programs that could potentially be broken by this situation are
  already fragile, and somewhat contrived: For example, a user-defined
  class that has conversion overloads both to <tt>long</tt> and
  to <tt>float</tt>.  If <tt>x</tt> is a value of such a class, then
  <tt>abs(x)</tt> would give the <tt>long</tt> version if the user
  included &lt;cstdlib&gt;, the <tt>float</tt> version if the user
  included &lt;cmath&gt;, and would be diagnosed as ambiguous at
  compile time if the user included both headers.  The LWG couldn't
  find an example of a program whose meaning would be changed (as
  opposed to changing it from well-formed to ill-formed) simply by
  adding another standard header.</p>

<p>Since the harm seems minimal, and there don't seem to be any simple
  and noninvasive solutions, this is being closed as NAD.  It is
  marked as "Future" for two reasons.  First, it might be useful to
  define an <tt>&lt;all&gt;</tt> header that would include all
  Standard Library headers.  Second, we should at least make sure that
  future library extensions don't make this problem worse.</p>
<hr>
<a name="326"><h3>326.&nbsp;Missing typedef in moneypunct_byname</h3></a><p><b>Section:</b>&nbsp;22.2.6.4 <a href="lib-locales.html#lib.locale.moneypunct.byname"> [lib.locale.moneypunct.byname]</a>&nbsp; <b>Status:</b>&nbsp;<a href="lwg-active.html#NAD">NAD</a>&nbsp; <b>Submitter:</b>&nbsp;Martin Sebor&nbsp; <b>Date:</b>&nbsp;05 Jul 2001</p>
<p>The definition of the moneypunct facet contains the typedefs char_type
and string_type. Only one of these names, string_type, is defined in
the derived facet, moneypunct_byname.</p>
<p><b>Proposed resolution:</b></p>
<p>For consistency with the numpunct facet, add a typedef for
char_type to the definition of the moneypunct_byname facet in
22.2.6.4 <a href="lib-locales.html#lib.locale.moneypunct.byname"> [lib.locale.moneypunct.byname]</a>.</p>
<p><b>Rationale:</b></p>
<p>The absence of the typedef is irrelevant.  Users can still access
the typedef, because it is inherited from the base class.</p>
<hr>
<a name="330"><h3>330.&nbsp;Misleading "exposition only" value in class locale definition</h3></a><p><b>Section:</b>&nbsp;22.1.1 <a href="lib-locales.html#lib.locale"> [lib.locale]</a>&nbsp; <b>Status:</b>&nbsp;<a href="lwg-active.html#NAD">NAD</a>&nbsp; <b>Submitter:</b>&nbsp;Martin Sebor&nbsp; <b>Date:</b>&nbsp;15 Jul 2001</p>
<p>
The "exposition only" value of the std::locale::none constant shown in
the definition of class locale is misleading in that it on many
systems conflicts with the value assigned to one if the LC_XXX
constants (specifically, LC_COLLATE on AIX, LC_ALL on HP-UX, LC_CTYPE
on Linux and SunOS). This causes incorrect behavior when such a
constant is passed to one of the locale member functions that accept a
locale::category argument and interpret it as either the C LC_XXX
constant or a bitmap of locale::category values. At least three major
implementations adopt the suggested value without a change and
consequently suffer from this problem.
</p>

<p>
For instance, the following code will (presumably) incorrectly copy facets
belonging to the collate category from the German locale on AIX:
</p>

<pre>
  std::locale l (std::locale ("C"), "de_DE", std::locale::none);
</pre>
<p><b>Proposed resolution:</b></p>
<p><b>Rationale:</b></p>
<p>The LWG agrees that it may be difficult to implement locale member
functions in such a way that they can take either <tt>category</tt>
arguments or the LC_ constants defined in &lt;cctype&gt;.  In light of
this requirement (22.1.1.1.1 <a href="lib-locales.html#lib.locale.category"> [lib.locale.category]</a>, paragraph 2), and in light
of the requirement in the preceding paragraph that it is possible to
combine <tt>category</tt> bitmask elements with bitwise operations,
defining the <tt>category</tt> elements is delicate,
particularly if an implementor is constrained to work with a
preexisting C library.  (Just using the existing LC_ constants would
not work in general.)  There's no set of "exposition only" values that
could give library implementors proper guidance in such a delicate
matter.  The non-normative example we're giving is no worse than
any other choice would be.</p>

<p>See issue <a href="lwg-defects.html#347">347</a>.</p>
<hr>
<a name="332"><h3>332.&nbsp;Consider adding increment and decrement operators to std::fpos&lt; T &gt; </h3></a><p><b>Section:</b>&nbsp;27.4.3 <a href="lib-iostreams.html#lib.fpos"> [lib.fpos]</a>&nbsp; <b>Status:</b>&nbsp;<a href="lwg-active.html#NAD">NAD</a>&nbsp; <b>Submitter:</b>&nbsp;PremAnand M. Rao&nbsp; <b>Date:</b>&nbsp;27 Aug 2001</p>
<p>
Increment and decrement operators are missing from 
Table 88 -- Position type requirements in 27.4.3 <a href="lib-iostreams.html#lib.fpos"> [lib.fpos]</a>.
</p>
<p><b>Proposed resolution:</b></p>
<p>
Table 88 (section 27.4.3) -- Position type requirements
be updated to include increment and decrement operators.
</p>

<pre>
expression        return type     operational    note

++p               fpos&amp;           p += O(1)
p++               fpos            { P tmp = p;
                                    ++p;
                                    return tmp; }
--p               fpos&amp;           p -= O(1)
p--               fpos            { P tmp = p;
                                    --p;
                                    return tmp; }
</pre>

<p><b>Rationale:</b></p>
<p>The LWG believes this is a request for extension, not a defect
report.  Additionally, nobody saw a clear need for this extension;
<tt>fpos</tt> is used only in very limited ways.</p>
<hr>
<a name="343"><h3>343.&nbsp;Unspecified library header dependencies</h3></a><p><b>Section:</b>&nbsp;21 <a href="lib-strings.html#lib.strings"> [lib.strings]</a>, 23 <a href="lib-containers.html#lib.containers"> [lib.containers]</a>, 27 <a href="lib-iostreams.html#lib.input.output"> [lib.input.output]</a>&nbsp; <b>Status:</b>&nbsp;<a href="lwg-active.html#NAD">NAD</a>&nbsp;<a href="lwg-active.html#Future">Future</a>&nbsp; <b>Submitter:</b>&nbsp;Martin Sebor&nbsp; <b>Date:</b>&nbsp;09 Oct 2001</p>
<p>
The synopses of the C++ library headers clearly show which names are
required to be defined in each header. Since in order to implement the
classes and templates defined in these headers declarations of other
templates (but not necessarily their definitions) are typically
necessary the standard in 17.4.4, p1 permits library implementers to
include any headers needed to implement the definitions in each header.
</p>

<p>
For instance, although it is not explicitly specified in the synopsis of
&lt;string&gt;, at the point of definition of the std::basic_string template
the declaration of the std::allocator template must be in scope. All
current implementations simply include &lt;memory&gt; from within &lt;string&gt;,
either directly or indirectly, to bring the declaration of
std::allocator into scope.
</p>

<p>
Additionally, however, some implementation also include &lt;istream&gt; and
&lt;ostream&gt; at the top of &lt;string&gt; to bring the declarations of
std::basic_istream and std::basic_ostream into scope (which are needed
in order to implement the string inserter and extractor operators
(21.3.7.9 [lib.string.io])). Other implementations only include
&lt;iosfwd&gt;, since strictly speaking, only the declarations and not the
full definitions are necessary.
</p>

<p>
Obviously, it is possible to implement &lt;string&gt; without actually
providing the full definitions of all the templates std::basic_string
uses (std::allocator, std::basic_istream, and std::basic_ostream).
Furthermore, not only is it possible, doing so is likely to have a
positive effect on compile-time efficiency.
</p>

<p>
But while it may seem perfectly reasonable to expect a program that uses
the std::basic_string insertion and extraction operators to also
explicitly include &lt;istream&gt; or &lt;ostream&gt;, respectively, it doesn't seem
reasonable to also expect it to explicitly include &lt;memory&gt;. Since
what's reasonable and what isn't is highly subjective one would expect
the standard to specify what can and what cannot be assumed.
Unfortunately, that isn't the case.
</p>

<p>The examples below demonstrate the issue.</p>

<p>Example 1:</p>

<p>It is not clear whether the following program is complete:</p>

<pre>
#include &lt;string&gt;

extern std::basic_ostream&lt;char&gt; &amp;strm;

int main () {
    strm &lt;&lt; std::string ("Hello, World!\n");
}
</pre>    

<p>or whether one must explicitly include &lt;memory&gt; or
&lt;ostream&gt; (or both) in addition to &lt;string&gt; in order for
the program to compile.</p>


<p>Example 2:</p>

<p>Similarly, it is unclear whether the following program is complete:</p>

<pre>
#include &lt;istream&gt;

extern std::basic_iostream&lt;char&gt; &amp;strm;

int main () {
    strm &lt;&lt; "Hello, World!\n";
}
</pre>

<p>
or whether one needs to explicitly include &lt;ostream&gt;, and
perhaps even other headers containing the definitions of other
required templates:</p>

<pre>
#include &lt;ios&gt;
#include &lt;istream&gt;
#include &lt;ostream&gt;
#include &lt;streambuf&gt;

extern std::basic_iostream&lt;char&gt; &amp;strm;

int main () {
    strm &lt;&lt; "Hello, World!\n";
}
</pre>

<p>Example 3:</p>

<p>Likewise, it seems unclear whether the program below is complete:</p>
<pre>
#include &lt;iterator&gt;

bool foo (std::istream_iterator&lt;int&gt; a, std::istream_iterator&lt;int&gt; b)
{
    return a == b;
}

int main () { }
</pre>

<p>or whether one should be required to include &lt;istream&gt;.</p>

<p>There are many more examples that demonstrate this lack of a
requirement.  I believe that in a good number of cases it would be
unreasonable to require that a program explicitly include all the
headers necessary for a particular template to be specialized, but I
think that there are cases such as some of those above where it would
be desirable to allow implementations to include only as much as
necessary and not more.</p>
<p><b>Proposed resolution:</b></p>
<p>
For every C++ library header, supply a minimum set of other C++ library
headers that are required to be included by that header. The proposed
list is below (C++ headers for C Library Facilities, table 12 in
17.4.1.2, p3, are omitted):
</p>

<pre>
+------------+--------------------+
| C++ header |required to include |
+============+====================+
|&lt;algorithm&gt; |                    |
+------------+--------------------+
|&lt;bitset&gt;    |                    |
+------------+--------------------+
|&lt;complex&gt;   |                    |
+------------+--------------------+
|&lt;deque&gt;     |&lt;memory&gt;            |
+------------+--------------------+
|&lt;exception&gt; |                    |
+------------+--------------------+
|&lt;fstream&gt;   |&lt;ios&gt;               |
+------------+--------------------+
|&lt;functional&gt;|                    |
+------------+--------------------+
|&lt;iomanip&gt;   |&lt;ios&gt;               |
+------------+--------------------+
|&lt;ios&gt;       |&lt;streambuf&gt;         |
+------------+--------------------+
|&lt;iosfwd&gt;    |                    |
+------------+--------------------+
|&lt;iostream&gt;  |&lt;istream&gt;, &lt;ostream&gt;|
+------------+--------------------+
|&lt;istream&gt;   |&lt;ios&gt;               |
+------------+--------------------+
|&lt;iterator&gt;  |                    |
+------------+--------------------+
|&lt;limits&gt;    |                    |
+------------+--------------------+
|&lt;list&gt;      |&lt;memory&gt;            |
+------------+--------------------+
|&lt;locale&gt;    |                    |
+------------+--------------------+
|&lt;map&gt;       |&lt;memory&gt;            |
+------------+--------------------+
|&lt;memory&gt;    |                    |
+------------+--------------------+
|&lt;new&gt;       |&lt;exception&gt;         |
+------------+--------------------+
|&lt;numeric&gt;   |                    |
+------------+--------------------+
|&lt;ostream&gt;   |&lt;ios&gt;               |
+------------+--------------------+
|&lt;queue&gt;     |&lt;deque&gt;             |
+------------+--------------------+
|&lt;set&gt;       |&lt;memory&gt;            |
+------------+--------------------+
|&lt;sstream&gt;   |&lt;ios&gt;, &lt;string&gt;     |
+------------+--------------------+
|&lt;stack&gt;     |&lt;deque&gt;             |
+------------+--------------------+
|&lt;stdexcept&gt; |                    |
+------------+--------------------+
|&lt;streambuf&gt; |&lt;ios&gt;               |
+------------+--------------------+
|&lt;string&gt;    |&lt;memory&gt;            |
+------------+--------------------+
|&lt;strstream&gt; |                    |
+------------+--------------------+
|&lt;typeinfo&gt;  |&lt;exception&gt;         |
+------------+--------------------+
|&lt;utility&gt;   |                    |
+------------+--------------------+
|&lt;valarray&gt;  |                    |
+------------+--------------------+
|&lt;vector&gt;    |&lt;memory&gt;            |
+------------+--------------------+
</pre>
<p><b>Rationale:</b></p>
<p>The portability problem is real.  A program that works correctly on
one implementation might fail on another, because of different header
dependencies.  This problem was understood before the standard was
completed, and it was a conscious design choice.</p>
<p>One possible way to deal with this, as a library extension, would
be an &lt;all&gt; header.</p>
<hr>
<a name="344"><h3>344.&nbsp;grouping + showbase</h3></a><p><b>Section:</b>&nbsp;22.2.2 <a href="lib-locales.html#lib.category.numeric"> [lib.category.numeric]</a>&nbsp; <b>Status:</b>&nbsp;<a href="lwg-active.html#NAD">NAD</a>&nbsp; <b>Submitter:</b>&nbsp;Howard Hinnant&nbsp; <b>Date:</b>&nbsp;13 Oct 2001</p>
<p>
When both grouping and showbase are active and the basefield is octal, 
does the leading 0 participate in the grouping or not?  For example, 
should one format as: 0,123,456 or 0123,456?
</p>
<p>
An analogy can be drawn with hexadecimal.  It appears that 0x123,456 is 
preferred over 0x,123,456.  However, this analogy is not universally 
accepted to apply to the octal base.  The standard is not clear on how 
to format (or parse) in this manner.
</p>
<p><b>Proposed resolution:</b></p>
<p>
Insert into 22.2.3.1.2 <a href="lib-locales.html#lib.facet.numpunct.virtuals"> [lib.facet.numpunct.virtuals]</a> paragraph 3, just before the last
sentence:
</p>
<blockquote>
The leading hexadecimal base specifier "0x" does not participate in 
grouping.  The leading '0' octal base specifier may participate in 
grouping.  It is unspecified if the leading '0' participates in 
formatting octal numbers.  In parsing octal numbers, the implementation 
is encouraged to accept both the leading '0' participating in the 
grouping, and not participating (e.g. 0123,456 or 0,123,456).
</blockquote>
<p><b>Rationale:</b></p>
<p>
The current behavior may be unspecified, but it's not clear that it
matters.  This is an obscure corner case, since grouping is usually
intended for the benefit of humans and oct/hex prefixes are usually
intended for the benefit of machines.  There is not a strong enough
consensus in the LWG for action.
</p>
<hr>
<a name="348"><h3>348.&nbsp;Minor issue with std::pair operator&lt;</h3></a><p><b>Section:</b>&nbsp;20.2.2 <a href="lib-utilities.html#lib.pairs"> [lib.pairs]</a>&nbsp; <b>Status:</b>&nbsp;<a href="lwg-active.html#NAD">NAD</a>&nbsp;<a href="lwg-active.html#Future">Future</a>&nbsp; <b>Submitter:</b>&nbsp;Andy Sawyer&nbsp; <b>Date:</b>&nbsp;23 Oct 2001</p>
<p>
The current wording of 20.2.2 [lib.pairs] p6 precludes the use of
operator&lt; on any pair type which contains a pointer.
</p>
<p><b>Proposed resolution:</b></p>
<p>In 20.2.2 <a href="lib-utilities.html#lib.pairs"> [lib.pairs]</a> paragraph 6, replace:</p>
<pre>
    Returns: x.first &lt; y.first || (!(y.first &lt; x.first) &amp;&amp; x.second &lt;
        y.second).
</pre>
<p>With:</p>
<pre>
    Returns: std::less&lt;T1&gt;()( x.first, y.first ) ||
             (!std::less&lt;T1&gt;()( y.first, x.first) &amp;&amp; 
             std::less&lt;T2&gt;()( x.second, y.second ) )
</pre>

<p><b>Rationale:</b></p>
<p>This is an instance of a much more general problem.  If we want
  operator&lt; to translate to std::less for pairs of pointers, where
  do we draw the line?  The same issue applies to individual
  pointers, smart pointer wrappers, std::vector&lt;T*&gt;, and so
  on.</p>

<p>Andy Koenig suggests that the real issue here is that we aren't
  distinguishing adequately between two different orderings, a
  "useful ordering" and a "canonical ordering" that's used just
  because we sometimes need <i>some</i> ordering without caring much
  which ordering it is.  Another example of the later is typeinfo's
  <tt>before</tt>.</p>

<hr>
<a name="350"><h3>350.&nbsp;allocator&lt;&gt;::address</h3></a><p><b>Section:</b>&nbsp;20.4.1.1 <a href="lib-utilities.html#lib.allocator.members"> [lib.allocator.members]</a>, 20.1.5 <a href="lib-utilities.html#lib.allocator.requirements"> [lib.allocator.requirements]</a>, 17.4.1.1 <a href="lib-intro.html#lib.contents"> [lib.contents]</a>&nbsp; <b>Status:</b>&nbsp;<a href="lwg-active.html#NAD">NAD</a>&nbsp;<a href="lwg-active.html#Future">Future</a>&nbsp; <b>Submitter:</b>&nbsp;Nathan Myers&nbsp; <b>Date:</b>&nbsp;25 Oct 2001</p>
<p>See c++std-lib-9006 and c++std-lib-9007.  This issue is taken
verbatim from -9007.</p>

<p>
The core language feature allowing definition of operator&amp;() applied 
to any non-builtin type makes that operator often unsafe to use in 
implementing libraries, including the Standard Library.  The result
is that many library facilities fail for legal user code, such as
the fragment</p>
<pre>
  class A { private: A* operator&amp;(); };
  std::vector&lt;A&gt; aa;

  class B { };
  B* operator&amp;(B&amp;) { return 0; }
  std::vector&lt;B&gt; ba;
</pre>

<p>
In particular, the requirements table for Allocator (Table 32) specifies
no semantics at all for member address(), and allocator&lt;&gt;::address is 
defined in terms of unadorned operator &amp;.
</p>

<p><b>Proposed resolution:</b></p>
<p>
In 20.4.1.1, Change the definition of allocator&lt;&gt;::address from:</p>
<blockquote>
  Returns: &amp;x
</blockquote>

<p>to:</p>

<p>
  Returns: The value that the built in operator&amp;(x) would return if not 
  overloaded.
</p>

<p>
In 20.1.5, Table 32, add to the Notes column of the a.address(r) and
a.address(s) lines, respectively: 
</p>

<pre>
  allocator&lt;T&gt;::address(r)
  allocator&lt;T&gt;::address(s)
</pre> 

<p>In addition, in clause 17.4.1.1, add a statement:</p>

<blockquote> 
 The Standard Library does not apply operator&amp; to any type for which
 operator&amp; may be overloaded.
</blockquote> 

<p><b>Rationale:</b></p>
<p>The LWG believes both examples are ill-formed.  The contained type
is required to be CopyConstructible (20.1.3 <a href="lib-utilities.html#lib.copyconstructible"> [lib.copyconstructible]</a>), and that
includes the requirement that &amp;t return the usual types and
values. Since allocators are intended to be used in conjunction with
containers, and since the CopyConstructible requirements appear to
have been written to deal with the concerns of this issue, the LWG
feels it is NAD unless someone can come up with a well-formed example
exhibiting a problem.</p>

<p>It may well be that the CopyConstructible requirements are too
  restrictive and that either the container requirements or the
  CopyConstructive requirements should be relaxed, but that's a far
  larger issue.  Marking this issue as "future" as a pointer to that
  larger issue.</p>
<hr>
<a name="351"><h3>351.&nbsp;unary_negate and binary_negate: struct or class?</h3></a><p><b>Section:</b>&nbsp;20.3 <a href="lib-utilities.html#lib.function.objects"> [lib.function.objects]</a>&nbsp; <b>Status:</b>&nbsp;<a href="lwg-active.html#NAD">NAD</a>&nbsp; <b>Submitter:</b>&nbsp;Dale Riley&nbsp; <b>Date:</b>&nbsp;12 Nov 2001</p>
<p>
In 20.3 <a href="lib-utilities.html#lib.function.objects"> [lib.function.objects]</a> the header &lt;functional&gt; synopsis declares
the unary_negate and binary_negate function objects as struct.
However in 20.3.5 <a href="lib-utilities.html#lib.negators"> [lib.negators]</a> the unary_negate and binary_negate
function objects are defined as class.  Given the context, they are
not "basic function objects" like negate, so this is either a typo or
an editorial oversight.
</p>

<p><i>[Taken from comp.std.c++]</i></p>
<p><b>Proposed resolution:</b></p>
<p>Change the synopsis to reflect the useage in 20.3.5 <a href="lib-utilities.html#lib.negators"> [lib.negators]</a></p>

<p><i>[Cura&ccedil;ao: Since the language permits "struct", the LWG
views this as NAD. They suggest, however, that the Project Editor
might wish to make the change as editorial.]</i></p>

<hr>
<a name="353"><h3>353.&nbsp;<tt>std::pair</tt> missing template assignment</h3></a><p><b>Section:</b>&nbsp;20.2.2 <a href="lib-utilities.html#lib.pairs"> [lib.pairs]</a>&nbsp; <b>Status:</b>&nbsp;<a href="lwg-active.html#NAD">NAD</a>&nbsp;<a href="lwg-active.html#Future">Future</a>&nbsp; <b>Submitter:</b>&nbsp;Martin Sebor&nbsp; <b>Date:</b>&nbsp;2 Dec 2001</p>
<p>
The class template <tt>std::pair</tt> defines a template ctor (20.2.2, p4) but
no template assignment operator. This may lead to inefficient code since
assigning an object of <tt>pair&lt;C, D&gt;</tt> to <tt>pair&lt;A, B&gt;</tt>
where the types <tt>C</tt> and <tt>D</tt> are distinct from but convertible to
<tt>A</tt> and <tt>B</tt>, respectively, results in a call to the template copy
ctor to construct an unnamed temporary of type <tt>pair&lt;A, B&gt;</tt>
followed by an ordinary (perhaps implicitly defined) assignment operator,
instead of just a straight assignment.
</p>
<p><b>Proposed resolution:</b></p>
<p>
Add the following declaration to the definition of <tt>std::pair</tt>:
</p>
<pre>
    template&lt;class U, class V&gt;
    pair&amp; operator=(const pair&lt;U, V&gt; &amp;p);
</pre>
<p>
And also add a paragraph describing the effects of the function template to the
end of 20.2.2:
</p>
<pre>
    template&lt;class U, class V&gt;
    pair&amp; operator=(const pair&lt;U, V&gt; &amp;p);
</pre>
<p>
    <b>Effects</b>: <tt>first = p.first;</tt>
                    <tt>second = p.second;</tt>
    <b>Returns</b>: <tt>*this</tt>
</p>

<p><i>[Cura&ccedil;ao: There is no indication this is was anything other than
a design decision, and thus NAD.&nbsp; May be appropriate for a future
standard.]</i></p>

<hr>
<a name="357"><h3>357.&nbsp;&lt;cmath&gt; float functions cannot return HUGE_VAL</h3></a><p><b>Section:</b>&nbsp;26.5 <a href="lib-numerics.html#lib.c.math"> [lib.c.math]</a>&nbsp; <b>Status:</b>&nbsp;<a href="lwg-active.html#NAD">NAD</a>&nbsp; <b>Submitter:</b>&nbsp;Ray Lischner&nbsp; <b>Date:</b>&nbsp;26 Feb 2002</p>
<p>
The float versions of the math functions have no meaningful value to return 
for a range error. The long double versions have a value they can return, 
but it isn't necessarily the most reasonable value.
</p>

<p>
Section 26.5 [lib.c.math], paragraph 5, says that C++ "adds float and long 
double overloaded versions of these functions, with the same semantics," 
referring to the math functions from the C90 standard.
</p>

<p>
The C90 standard, in section 7.5.1, paragraph 3, says that functions return 
"the value of the macro HUGE_VAL" when they encounter a range error. 
Section 7.5, paragraph 2, defines HUGE_VAL as a macro that "expands to a 
positive double expression, not necessarily representable as a float."
</p>

<p>
Therefore, the float versions of the math functions have no way to
signal a range error. <i>[Cura&ccedil;ao: The LWG notes that this isn't
strictly correct, since errno is set.]</i> The semantics require that they
return HUGE_VAL, but they cannot because HUGE_VAL might not be
representable as a float.
</p>

<p>
The problem with long double functions is less severe because HUGE_VAL is 
representable as a long double. On the other hand, it might not be a "huge" 
long double value, and might fall well within the range of normal return 
values for a long double function. Therefore, it does not make sense for a 
long double function to return a double (HUGE_VAL) for a range error.
</p>
<p><b>Proposed resolution:</b></p>
<p>Cura&ccedil;ao: C99 was faced with a similar problem, which they fixed by
adding HUGE_VALF and HUGE_VALL in addition to HUGE_VAL.</p>

<p>C++ must also fix, but it should be done in the context of the
general C99 based changes to C++, not via DR. Thus the LWG in Cura&ccedil;ao
felt the resolution should be NAD, FUTURE, but the issue is being held
open for one more meeting to ensure LWG members not present during the
discussion concur.</p>
<p><b>Rationale:</b></p>
<p>Will be fixed as part of more general work in the TR.</p>
<hr>
<a name="361"><h3>361.&nbsp;num_get&lt;&gt;::do_get (..., void*&amp;) checks grouping</h3></a><p><b>Section:</b>&nbsp;22.2.2.2.2 <a href="lib-locales.html#lib.facet.num.put.virtuals"> [lib.facet.num.put.virtuals]</a>&nbsp; <b>Status:</b>&nbsp;<a href="lwg-active.html#NAD">NAD</a>&nbsp; <b>Submitter:</b>&nbsp;Martin Sebor&nbsp; <b>Date:</b>&nbsp;12 Mar 2002</p>
<p>
22.2.2.2.2, p12 specifies that <tt>thousands_sep</tt> is to be inserted only
for integral types (issue 282 suggests that this should be done for
all arithmetic types).
</p>

<p>
22.2.2.1.2, p12 requires that grouping be checked for all extractors
including that for <tt>void*</tt>.
</p>

<p>
I don't think that's right. <tt>void*</tt> values should not be checked for
grouping, should they? (Although if they should, then <tt>num_put</tt> needs
to write them out, otherwise their extraction will fail.)
</p>
<p><b>Proposed resolution:</b></p>
<p>
Change the first sentence of 22.2.2.2.2, p12 from
</p>
<blockquote>
    Digit grouping is checked. That is, the positions of discarded
    separators is examined for consistency with
    use_facet&lt;numpunct&lt;charT&gt; &gt;(loc).grouping().
    If they are not consistent then ios_base::failbit is assigned
    to err.
</blockquote>

<p>to</p>
<blockquote>
    Except for conversions to void*, digit grouping is checked...
</blockquote>

<p><b>Rationale:</b></p>
<p>This would be a change: as it stands, the standard clearly
  specifies that grouping applies to void*.  A survey of existing
  practice shows that most existing implementations do that, as they
  should.</p>
<hr>
<a name="367"><h3>367.&nbsp;remove_copy/remove_copy_if and Input Iterators</h3></a><p><b>Section:</b>&nbsp;25.2.7 <a href="lib-algorithms.html#lib.alg.remove"> [lib.alg.remove]</a>&nbsp; <b>Status:</b>&nbsp;<a href="lwg-active.html#NAD">NAD</a>&nbsp; <b>Submitter:</b>&nbsp;Anthony Williams&nbsp; <b>Date:</b>&nbsp;13 May 2002</p>
<p>
remove_copy and remove_copy_if (25.2.7 <a href="lib-algorithms.html#lib.alg.remove"> [lib.alg.remove]</a>) permit their
input range to be marked with Input Iterators. However, since two
operations are required against the elements to copy (comparison and
assigment), when the input range uses Input Iterators, a temporary
copy must be taken to avoid dereferencing the iterator twice. This
therefore requires the value type of the InputIterator to be
CopyConstructible. If the iterators are at least Forward Iterators,
then the iterator can be dereferenced twice, or a reference to the
result maintained, so the temporary is not required.
</p>
<p><b>Proposed resolution:</b></p>
<p>
Add "If InputIterator does not meet the requirements of forward
iterator, then the value type of InputIterator must be copy
constructible. Otherwise copy constructible is not required." to
25.2.7 <a href="lib-algorithms.html#lib.alg.remove"> [lib.alg.remove]</a> paragraph 6.
</p>
<p><b>Rationale:</b></p>
<p>The assumption is that an input iterator can't be dereferenced
  twice.  There's no basis for that assumption in the Standard.</p>
<hr>
<a name="372"><h3>372.&nbsp;Inconsistent description of stdlib exceptions</h3></a><p><b>Section:</b>&nbsp;17.4.4.8 <a href="lib-intro.html#lib.res.on.exception.handling"> [lib.res.on.exception.handling]</a>, 18.6.1 <a href="lib-support.html#lib.exception"> [lib.exception]</a>, &nbsp; <b>Status:</b>&nbsp;<a href="lwg-active.html#NAD">NAD</a>&nbsp; <b>Submitter:</b>&nbsp;Randy Maddox&nbsp; <b>Date:</b>&nbsp;22 Jul 2002</p>

<p>Paragraph 3 under clause 17.4.4.8 <a href="lib-intro.html#lib.res.on.exception.handling"> [lib.res.on.exception.handling]</a>, Restrictions on
Exception Handling, states that "Any other functions defined in the
C++ Standard Library that do not have an exception-specification may
throw implementation-defined exceptions unless otherwise specified."
This statement is followed by a reference to footnote 178 at the
bottom of that page which states, apparently in reference to the C++
Standard Library, that "Library implementations are encouraged (but
not required) to report errors by throwing exceptions from (or derived
from) the standard exceptions."</p>

<p>These statements appear to be in direct contradiction to clause
18.6.1 <a href="lib-support.html#lib.exception"> [lib.exception]</a>, which states "The class exception defines the
base class for the types of objects thrown as exceptions by the C++
Standard library components ...".</p>

<p>Is this inconsistent?</p>

<p><b>Proposed resolution:</b></p>
<p><b>Rationale:</b></p>
<p>Clause 17 is setting the overall library requirements, and it's
  clear and consistent.  This sentence from Clause 18 is descriptive,
  not setting a requirement on any other class.
</p>
<hr>
<a name="374"><h3>374.&nbsp;moneypunct::frac_digits returns int not unsigned</h3></a><p><b>Section:</b>&nbsp;22.2.6.3.1 <a href="lib-locales.html#lib.locale.moneypunct.members"> [lib.locale.moneypunct.members]</a>, 22.2.6.3.2 <a href="lib-locales.html#lib.locale.moneypunct.virtuals"> [lib.locale.moneypunct.virtuals]</a>&nbsp; <b>Status:</b>&nbsp;<a href="lwg-active.html#NAD">NAD</a>&nbsp; <b>Submitter:</b>&nbsp;Ray Lischner&nbsp; <b>Date:</b>&nbsp;8 Aug 2002</p>
<p>
In section 22.2.6.3.1 <a href="lib-locales.html#lib.locale.moneypunct.members"> [lib.locale.moneypunct.members]</a>, frac_digits() returns type
"int". This implies that frac_digits() might return a negative value,
but a negative value is nonsensical. It should return "unsigned".
</p>

<p>
Similarly, in section 22.2.6.3.2 <a href="lib-locales.html#lib.locale.moneypunct.virtuals"> [lib.locale.moneypunct.virtuals]</a>, do_frac_digits()
should return "unsigned".
</p>

<p><b>Proposed resolution:</b></p>
<p><b>Rationale:</b></p>
<p>Regardless of whether the return value is int or unsigned, it's
always conceivable that frac_digits might return a nonsensical
value. (Is 4294967295 really any better than -1?)  The clients of
moneypunct, the get and put facets, can and do perform range
checks.</p>
<hr>
<a name="377"><h3>377.&nbsp;basic_string::insert and length_error</h3></a><p><b>Section:</b>&nbsp;21.3.5.4 <a href="lib-strings.html#lib.string::insert"> [lib.string::insert]</a>&nbsp; <b>Status:</b>&nbsp;<a href="lwg-active.html#NAD">NAD</a>&nbsp; <b>Submitter:</b>&nbsp;Ray Lischner&nbsp; <b>Date:</b>&nbsp;16 Aug 2002</p>
<p>
Section 21.3.5.4 <a href="lib-strings.html#lib.string::insert"> [lib.string::insert]</a>, paragraph 4, contains the following,
"Then throws length_error if size() &gt;= npos - rlen."
</p>

<p>
Related to DR 83, this sentence should probably be removed.
</p>
<p><b>Proposed resolution:</b></p>
<p><b>Rationale:</b></p>
<p>This requirement is redundant but correct.  No change is
needed.</p>
<hr>
<a name="378"><h3>378.&nbsp;locale immutability and locale::operator=()</h3></a><p><b>Section:</b>&nbsp;22.1.1 <a href="lib-locales.html#lib.locale"> [lib.locale]</a>&nbsp; <b>Status:</b>&nbsp;<a href="lwg-active.html#Dup">Dup</a>&nbsp; <b>Submitter:</b>&nbsp;Martin Sebor&nbsp; <b>Date:</b>&nbsp;6 Sep 2002</p>
<p>
I think there is a problem with 22.1.1, p6 which says that
</p>
<pre>
    -6- An instance of locale is immutable; once a facet reference
        is obtained from it, that reference remains usable as long
        as the locale value itself exists.
</pre>
<p>
and 22.1.1.2, p4:
</p>
<pre>
    const locale&amp; operator=(const locale&amp; other) throw();

    -4- Effects: Creates a copy of other, replacing the current value.
</pre>
<p>
How can a reference to a facet obtained from a locale object remain
valid after an assignment that clearly must replace all the facets
in the locale object? Imagine a program such as this
</p>
<pre>
    std::locale loc ("de_DE");
    const std::ctype&lt;char&gt; &amp;r0 = std::use_facet&lt;std::ctype&lt;char&gt; &gt;(loc);
    loc = std::locale ("en_US");
    const std::ctype&lt;char&gt; &amp;r1 = std::use_facet&lt;std::ctype&lt;char&gt; &gt;(loc);
</pre>
<p>
Is r0 really supposed to be preserved and destroyed only when loc goes
out of scope?
</p>
<p><b>Proposed resolution:</b></p>
<p><i>[Summer '04 mid-meeting mailing: Martin and Dietmar believe this
  is a duplicate of issue <a href="lwg-defects.html#31">31</a> and recommend that it be
  closed.
]</i></p>

<hr>
<a name="388"><h3>388.&nbsp;Use of complex as a key in associative containers</h3></a><p><b>Section:</b>&nbsp;26.2 <a href="lib-numerics.html#lib.complex.numbers"> [lib.complex.numbers]</a>&nbsp; <b>Status:</b>&nbsp;<a href="lwg-active.html#NAD">NAD</a>&nbsp;<a href="lwg-active.html#Future">Future</a>&nbsp; <b>Submitter:</b>&nbsp;Gabriel Dos Reis&nbsp; <b>Date:</b>&nbsp;8 Nov 2002</p>
<p>
Practice with std::complex&lt;&gt; and the associative containers
occasionally reveals artificial and distracting issues with constructs
resembling: std::set&lt;std::complex&lt;double&gt; &gt; s;
</p>

<p>
The main reason for the above to fail is the absence of an approriate
definition for std::less&lt;std::complex&lt;T&gt; &gt;. That in turn comes from
the definition of the primary template std::less&lt;&gt; in terms of
operator&lt;.
</p>

<p>
The usual argument goes as follows: Since there is no ordering over
the complex field compatible with field operations it makes little
sense to define a function operator&lt; operating on the datatype
std::complex&lt;T&gt;.  That is fine. However, that reasoning does not carry
over to std::less&lt;T&gt; which is used, among other things, by associative
containers as an ordering useful to meet complexity requirements.
</p>

<p>Related issue: <a href="lwg-closed.html#348">348</a>.</p>

<p><b>Proposed resolution:</b></p>
<p>Informally: Add a specialization of std::less for std::complex.</p>
<p><b>Rationale:</b></p>
<p>Discussed in Santa Cruz.  An overwhelming majority of the LWG
believes this should not be treated a DR: it's a request for a design
change, not a defect in the existing standard.  Most people (10-3)
believed that we probably don't want this change, period: as with
issue <a href="lwg-closed.html#348">348</a>, it's hard to know where to draw the line.
The LWG noted that users who want to put objects into an associative
container for which <tt>operator&lt;</tt> isn't defined can simply
provide their own comparison function object.</p>
<hr>
<a name="390"><h3>390.&nbsp;CopyConstructible requirements too strict</h3></a><p><b>Section:</b>&nbsp;20.1.3 <a href="lib-utilities.html#lib.copyconstructible"> [lib.copyconstructible]</a>&nbsp; <b>Status:</b>&nbsp;<a href="lwg-active.html#NAD">NAD</a>&nbsp;<a href="lwg-active.html#Future">Future</a>&nbsp; <b>Submitter:</b>&nbsp;Doug Gregor&nbsp; <b>Date:</b>&nbsp;24 Oct 2002</p>
<p>
The CopyConstructible requirements in Table 30 state that for an
object t of type T (where T is CopyConstructible), the expression &amp;t
returns the address of t (with type T*). This requirement is overly
strict, in that it disallows types that overload operator&amp; to not
return a value of type T*. This occurs, for instance, in the <a href="http://www.boost.org/libs/lambda">Boost.Lambda</a> library, where
operator&amp; is overloaded for a Boost.Lambda function object to return
another function object.
</p>

<p>Example:</p>

<pre>
  std::vector&lt;int&gt; u, v;
  int x;
  // ...
  std::transform(u.begin(), u.end(), std::back_inserter(v), _1 * x);
</pre>

<p>
_1 * x returns an unnamed function object with operator&amp; overloaded to
not return T* , therefore rendering the std::transform call ill-formed.
However, most standard library implementations will compile this code
properly, and the viability of such binder libraries is severely hindered
by the unnecessary restriction in the CopyConstructible requirements.
</p>

<p>
For reference, the address of an object can be retrieved without using
the address-of operator with the following function template:
</p>

<pre>
  template &lt;typename T&gt; T* addressof(T&amp; v)
  {
    return reinterpret_cast&lt;T*&gt;(
         &amp;const_cast&lt;char&amp;&gt;(reinterpret_cast&lt;const volatile char &amp;&gt;(v)));
  }
</pre>

<p>
Note: this relates directly to library issue <a href="lwg-closed.html#350">350</a>, which
will need to be reexamined if the CopyConstructible requirements
change.
</p>
<p><b>Proposed resolution:</b></p>
<p>
Remove the last two rows of Table 30, eliminating the requirements
that &amp;t and &amp;u return the address of t and u, respectively.
</p>
<p><b>Rationale:</b></p>
<p>This was a deliberate design decision.  Perhaps it should be
   reconsidered for C++0x. </p>
<hr>
<a name="392"><h3>392.&nbsp;'equivalence' for input iterators</h3></a><p><b>Section:</b>&nbsp;24.1.1 <a href="lib-iterators.html#lib.input.iterators"> [lib.input.iterators]</a>&nbsp; <b>Status:</b>&nbsp;<a href="lwg-active.html#NAD">NAD</a>&nbsp; <b>Submitter:</b>&nbsp;Corwin Joy&nbsp; <b>Date:</b>&nbsp;11 Dec 2002</p>

<p>
In section 24.1.1 <a href="lib-iterators.html#lib.input.iterators"> [lib.input.iterators]</a> table 72 -
'Input Iterator Requirements' we have as a postcondition of *a:
"If a==b and (a, b) is in the domain of == then *a is equivalent to *b".
</p>

<p>
In section 24.5.3.5 <a href="lib-iterators.html#lib.istreambuf.iterator::equal"> [lib.istreambuf.iterator::equal]</a> it states that
"istreambuf_iterator::equal returns true if and only if both iterators
are at end-of-stream, or neither is at end-of-stream, <i>regardless of
what streambuf object they use</i>."  (My emphasis).
</p>

<p>
The defect is that either 'equivalent' needs to be more precisely
defined or the conditions for equality in 24.5.3.5 <a href="lib-iterators.html#lib.istreambuf.iterator::equal"> [lib.istreambuf.iterator::equal]</a>
are incorrect. (Or both).
</p>

<p>Consider the following example:</p>
<pre>
   #include &lt;iostream&gt;
   #include &lt;fstream&gt;
   #include &lt;iterator&gt;
   using namespace std;

   int main() {
    ifstream file1("file1.txt"), file2("file2.txt");
    istreambuf_iterator&lt;char&gt; f1(file1), f2(file2);
    cout &lt;&lt; "f1 == f2 : " &lt;&lt; boolalpha &lt;&lt; (f1 == f2) &lt;&lt; endl;
    cout &lt;&lt; "f1 = " &lt;&lt; *f1 &lt;&lt; endl;
    cout &lt;&lt; "f2 = " &lt;&lt; *f2 &lt;&lt; endl;
    return 0;
   }
</pre>

<p>Now assuming that neither f1 or f2 are at the end-of-stream then
f1 == f2 by 24.5.3.5 <a href="lib-iterators.html#lib.istreambuf.iterator::equal"> [lib.istreambuf.iterator::equal]</a>.</p>

<p>However, it is unlikely that *f1 will give the same value as *f2 except
by accident.</p>

<p>So what does *f1 'equivalent' to *f2 mean?  I think the standard should
be clearer on this point, or at least be explicit that this does not
mean that *f1 and *f2 are required to have the same value in the case
of input iterators.</p>
<p><b>Proposed resolution:</b></p>
<p><b>Rationale:</b></p>
<p>The two iterators aer not in the domain of ==</p>
<hr>
<a name="399"><h3>399.&nbsp;volations of unformatted input function requirements</h3></a><p><b>Section:</b>&nbsp;27.6.1.3 <a href="lib-iostreams.html#lib.istream.unformatted"> [lib.istream.unformatted]</a>&nbsp; <b>Status:</b>&nbsp;<a href="lwg-active.html#NAD">NAD</a>&nbsp; <b>Submitter:</b>&nbsp;Martin Sebor&nbsp; <b>Date:</b>&nbsp;5 Jan 2003</p>
    <p>
The Effects clauses for the two functions below violate the
general requirements on unformatted input functions outlined
in 27.6.1.3: they do not begin by constructing a sentry object.
Instead, they begin by calling widen ('\n'), which may throw
an exception. The exception is then allowed to propagate from
the unformatted input function irrespective of the setting of
exceptions().
    </p>
    <p>
Note that in light of 27.6.1.1, p3 and p4, the fact that the
functions allow exceptions thrown from widen() to propagate
may not strictly speaking be a defect (but the fact that the
functions do not start by constructing a sentry object still
is). However, since an exception thrown from ctype&lt;charT&gt;
::widen() during any other input operation (say, from within
a call to num_get&lt;charT&gt;::get()) will be caught and cause
badbit to be set, these two functions should not be treated
differently for the sake of consistency.
    </p>
  <p><b>Proposed resolution:</b></p>
<p><b>Rationale:</b></p>
<p>
Not a defect.  The standard is consistent, and the behavior required
by the standard is unambiguous.  Yes, it's theoretically possible for
widen to throw.  (Not that this will happen for the default ctype
facet or for most real-world replacement ctype facets.)  Users who
define ctype facets that can throw, and who care about this behavior,
can use alternative signatures that don't call widen.
</p>
<hr>
<a name="429"><h3>429.&nbsp;typo in basic_ios::clear(iostate)</h3></a><p><b>Section:</b>&nbsp;27.4.4.3 <a href="lib-iostreams.html#lib.iostate.flags"> [lib.iostate.flags]</a>&nbsp; <b>Status:</b>&nbsp;<a href="lwg-active.html#Dup">Dup</a>&nbsp; <b>Submitter:</b>&nbsp;Martin Sebor&nbsp; <b>Date:</b>&nbsp;18 Sep 2003</p>
        <p>

The Effects clause in 27.4.4.3, p5 describing the effects of a call to
the ios_base member function clear(iostate state) says that the function
only throws if the respective bits are already set prior to the function
call. That's obviously not the intent. If it was, a call to clear(badbit)
on an object for which (rdstate() == goodbit &amp;&amp; exceptions() == badbit)
holds would not result in an exception being thrown.

        </p>
    <p><b>Proposed resolution:</b></p>
        <p>

The text ought to be changed from
<br>

"If (rdstate() &amp; exceptions()) == 0, returns. ..."
<br>

to
<br>

"If (state &amp; exceptions()) == 0, returns. ..."
        </p>
<p><b>Rationale:</b></p>
<p>This is a duplicate of issue <a href="lwg-defects.html#412">412</a>.</p>
<hr>
<a name="433"><h3>433.&nbsp;Contradiction in specification of unexpected()</h3></a><p><b>Section:</b>&nbsp;18.6.2.4 <a href="lib-support.html#lib.unexpected"> [lib.unexpected]</a>&nbsp; <b>Status:</b>&nbsp;<a href="lwg-active.html#NAD">NAD</a>&nbsp; <b>Submitter:</b>&nbsp;Vyatcheslav Sysoltsev&nbsp; <b>Date:</b>&nbsp;29 Sep 2003</p>
<p>
Clause 15.5.2 <a href="except.html#except.unexpected"> [except.unexpected]</a> paragraph 1 says that "void unexpected();
is called (18.6.2) immediately after completing the stack unwinding
for the former function", but 18.6.2.4 (Effects) says that "void
unexpected(); . . . Calls the unexpected_handler function in effect
immediately after evaluating the throwexpression (18.6.2.2),".  Isn't
here a contradiction: 15.5.2 requires stack have been unwound when in
void unexpected() and therefore in unexpected_handler but 18.6.2.4
claims that unexpected_handler is called "in effect immediately" after
evaluation of throw expression is finished, so there is no space left
for stack to be unwound therefore?  I think the phrase "in effect
immediately" should be removed from the standard because it brings
ambiguity in understanding.
</p>
<p><b>Proposed resolution:</b></p>
<p><b>Rationale:</b></p>
<p>There is no contradiction.  The phrase "in effect immediately" is
  just to clarify which handler is to be called.</p>
<hr>
<a name="437"><h3>437.&nbsp;Formatted output of function pointers is confusing</h3></a><p><b>Section:</b>&nbsp;27.6.2.5.2 <a href="lib-iostreams.html#lib.ostream.inserters.arithmetic"> [lib.ostream.inserters.arithmetic]</a>&nbsp; <b>Status:</b>&nbsp;<a href="lwg-active.html#NAD">NAD</a>&nbsp; <b>Submitter:</b>&nbsp;Ivan Godard&nbsp; <b>Date:</b>&nbsp;24 Oct 2003</p>
<p>
Given:
</p>
<pre>
void f(int) {}
void(*g)(int) = f;
cout &lt;&lt; g;
</pre>

<p>
(with the expected #include and usings), the value printed is a rather
surprising "true". Rather useless too.
</p>

<p>The standard defines:</p>

<pre>ostream&amp; operator&lt;&lt;(ostream&amp;, void*);</pre>

<p>which picks up all data pointers and prints their hex value, but does
not pick up function pointers because there is no default conversion
from function pointer to void*. Absent that, we fall back to legacy
conversions from C and the function pointer is converted to bool.
</p>

<p>There should be an analogous inserter that prints the address of a
  function pointer.</p>
<p><b>Proposed resolution:</b></p>
<p><b>Rationale:</b></p>
<p>This is indeed a wart, but there is no good way to solve it.  C
  doesn't provide a portable way of outputting the address of a
  function point either.</p>
<hr>
<a name="439"><h3>439.&nbsp;Should facets be copyable?</h3></a><p><b>Section:</b>&nbsp;22.2 <a href="lib-locales.html#lib.locale.categories"> [lib.locale.categories]</a>&nbsp; <b>Status:</b>&nbsp;<a href="lwg-active.html#NAD">NAD</a>&nbsp; <b>Submitter:</b>&nbsp;Matt Austern&nbsp; <b>Date:</b>&nbsp;2 Nov 2003</p>
<p>The following facets classes have no copy constructors described in
  the standard, which, according to the standard, means that they are
  supposed to use the compiler-generated defaults.  Default copy
  behavior is probably inappropriate.  We should either make these
  classes uncopyable or else specify exactly what their constructors do.</p>

<p>Related issue: <a href="lwg-active.html#421">421</a>.</p>

<pre>
        ctype_base
        ctype
        ctype_byname
        ctype&lt;char&gt;
        ctype_byname&lt;char&gt;
        codecvt_base
        codecvt
        codecvt_byname
        num_get
        num_put
        numpunct
        numpunct_byname
        collate
        collate_byname
        time_base
        time_get
        time_get_byname
        time_put
        time_put_byname
        money_get
        money_put
        money_base
        moneypunct
        moneypunct_byname
        messages_base
        messages
        messages_byname
</pre>

<p><b>Proposed resolution:</b></p>
<p><b>Rationale:</b></p>
<p>The copy constructor in the base class is private.</p>
<hr>
<a name="440"><h3>440.&nbsp;Should std::complex use unqualified transcendentals?</h3></a><p><b>Section:</b>&nbsp;26.2.8 <a href="lib-numerics.html#lib.complex.transcendentals"> [lib.complex.transcendentals]</a>&nbsp; <b>Status:</b>&nbsp;<a href="lwg-active.html#NAD">NAD</a>&nbsp; <b>Submitter:</b>&nbsp;Matt Austern&nbsp; <b>Date:</b>&nbsp;5 Nov 2003</p>
<p>
Operations like <tt>pow</tt> and <tt>exp</tt> on
<tt>complex&lt;T&gt;</tt> are typically implemented in terms of
operations like <tt>sin</tt> and <tt>cos</tt> on <tt>T</tt>.  
Should implementations write this as <tt>std::sin</tt>, or as plain
unqualified <tt>sin</tt>?
</p>

<p>The issue, of course, is whether we want to use
argument-dependent lookup in the case where <tt>T</tt> is a
user-defined type.  This is similar to the issue of valarray
transcendentals, as discussed in issue <a href="lwg-defects.html#226">226</a>.</p>

<p>This issue differs from valarray transcendentals in two important
ways.  First, "the effect of instantiating the template
<tt>complex</tt> for types other than float, double or long double is
unspecified." (26.2.1 <a href="lib-numerics.html#lib.complex.synopsis"> [lib.complex.synopsis]</a>) Second, the standard does not
dictate implementation, so there is no guarantee that a particular
real math function is used in the implementation of a particular
complex function.</p>

<p><b>Proposed resolution:</b></p>
<p><b>Rationale:</b></p>
<p>If you instantiate std::complex for user-defined types, all bets
are off.</p>
<hr>
<a name="447"><h3>447.&nbsp;Wrong template argument for time facets</h3></a><p><b>Section:</b>&nbsp;22.1.1.1.1 <a href="lib-locales.html#lib.locale.category"> [lib.locale.category]</a>&nbsp; <b>Status:</b>&nbsp;<a href="lwg-active.html#Dup">Dup</a>&nbsp; <b>Submitter:</b>&nbsp;Pete Becker&nbsp; <b>Date:</b>&nbsp;26 Dec 2003</p>
<p>
22.1.1.1.1/4, table 52, "Required Instantiations", lists, among others:
</p>
<pre>
    time_get&lt;char,InputIterator&gt;
    time_get_byname&lt;char,InputIterator&gt;
    time_get&lt;wchar_t,OutputIterator&gt;
    time_get_byname&lt;wchar_t,OutputIterator&gt;
</pre>

<p>
The second argument to the last two should be InputIterator, not
OutputIterator.
</p>
<p><b>Proposed resolution:</b></p>
<p>
Change the second template argument to InputIterator.
</p>
<p><b>Rationale:</b></p>
Duplicate of issue <a href="lwg-defects.html#327">327</a>
<hr>
<a name="450"><h3>450.&nbsp;set::find is inconsistent with associative container requirements</h3></a><p><b>Section:</b>&nbsp;23.3.3 <a href="lib-containers.html#lib.set"> [lib.set]</a>&nbsp; <b>Status:</b>&nbsp;<a href="lwg-active.html#Dup">Dup</a>&nbsp; <b>Submitter:</b>&nbsp;Bill Plauger&nbsp; <b>Date:</b>&nbsp;30 Jan 2004</p>
<p>map/multimap have:</p>

<pre>
	iterator find(const key_type&amp; x) const;
	const_iterator find(const key_type&amp; x) const;
</pre>

<p>
which is consistent with the table of associative container requirements.
But set/multiset have:
</p>
<pre>
	iterator find(const key_type&amp;) const;
</pre>

<p>
set/multiset should look like map/multimap, and honor the requirements
table, in this regard.
</p>
<p><b>Proposed resolution:</b></p>
<p><b>Rationale:</b></p>
<p>Duplicate of issue <a href="lwg-defects.html#214">214</a>.</p>
<hr>
<a name="451"><h3>451.&nbsp;Associative erase should return an iterator</h3></a><p><b>Section:</b>&nbsp;23.1.2 <a href="lib-containers.html#lib.associative.reqmts"> [lib.associative.reqmts]</a>, 23.3 <a href="lib-containers.html#lib.associative"> [lib.associative]</a>&nbsp; <b>Status:</b>&nbsp;<a href="lwg-active.html#Dup">Dup</a>&nbsp; <b>Submitter:</b>&nbsp;Bill Plauger&nbsp; <b>Date:</b>&nbsp;30 Jan 2004</p>
<p>map/multimap/set/multiset have:</p>
<pre>
	void erase(iterator);
	void erase(iterator, iterator);
</pre>

<p>But there's no good reason why these can't return an iterator, as for
vector/deque/list:</p>
<pre>
	iterator erase(iterator);
	iterator erase(iterator, iterator);
</pre>

<p><b>Proposed resolution:</b></p>
<p>
Informally: The table of associative container requirements, and the
relevant template classes, should return an iterator designating the
first element beyond the erased subrange.
</p>
<p><b>Rationale:</b></p>
<p>Duplicate of <a href="lwg-active.html#130">130</a></p>
<hr>
<a name="452"><h3>452.&nbsp; locale::combine should be permitted to generate a named locale</h3></a><p><b>Section:</b>&nbsp;22.1.1.3 <a href="lib-locales.html#lib.locale.members"> [lib.locale.members]</a>&nbsp; <b>Status:</b>&nbsp;<a href="lwg-active.html#NAD">NAD</a>&nbsp; <b>Submitter:</b>&nbsp;Bill Plauger&nbsp; <b>Date:</b>&nbsp;30 Jan 2004</p>
<pre>
template&lt;class Facet&gt;
	locale::combine(const locale&amp;) const;
</pre>
<p>
is obliged to create a locale that has no name. This is overspecification
and overkill. The resulting locale should follow the usual rules -- it
has a name if the locale argument has a name and Facet is one of the
standard facets.
</p>

<p><i>[
 Sydney and post-Sydney (see c++std-lib-13439, c++std-lib-13440,
 c++std-lib-13443): agreed that it's overkill to say that the locale
 is obligated to be nameless.  However, we also can't require it to
 have a name.  At the moment, locale names are based on categories
 and not on individual facets.  If a locale contains two different
 facets of different names from the same category, then this would
 not fit into existing naming schemes.  We need to give
 implementations more freedom.  Bill will provide wording.
]</i></p>

<p><b>Proposed resolution:</b></p>
<p><b>Rationale:</b></p>
<p>After further discussion the LWG decided to close this as NAD.
  The fundamental problem is that names right now are per-category,
  not per-facet.  The <tt>combine</tt> member function works at the
  wrong level of granularity.</p>
<hr>
<a name="483"><h3>483.&nbsp;Heterogeneous equality and EqualityComparable</h3></a><p><b>Section:</b>&nbsp;25.1 <a href="lib-algorithms.html#lib.alg.nonmodifying"> [lib.alg.nonmodifying]</a>, 25.2 <a href="lib-algorithms.html#lib.alg.modifying.operations"> [lib.alg.modifying.operations]</a>&nbsp; <b>Status:</b>&nbsp;<a href="lwg-active.html#Dup">Dup</a>&nbsp; <b>Submitter:</b>&nbsp;Peter Dimov&nbsp; <b>Date:</b>&nbsp;20 Sep 2004</p>
<p>c++std-lib-14262</p>

<p>[lib.alg.find] requires T to be EqualityComparable:</p>

<pre>
template &lt;class InputIterator, class T&gt;
   InputIterator find(InputIterator first, InputIterator last,
                      const T&amp; value);
</pre>

<p>
However the condition being tested, as specified in the Effects
clause, is actually *i == value, where i is an InputIterator.
</p>

<p>
The two clauses are in agreement only if the type of *i is T, but this
isn't necessarily the case. *i may have a heterogeneous comparison
operator that takes a T, or a T may be convertible to the type of *i.
</p>

<p>Further discussion (c++std-lib-14264): this problem affects a
  number of algorithsm in clause 25, not just <tt>find</tt>.  We
  should try to resolve this problem everywhere it appears.</p>
<p><b>Proposed resolution:</b></p>

<p>[lib.alg.find]:</p>
<blockquote>
   Remove [lib.alg.find]/1.
</blockquote>

<p>[lib.alg.count]:</p>
<blockquote>
   Remove [lib.alg.count]/1.
</blockquote>

<p>[lib.alg.search]:</p>
<blockquote>
   Remove "Type T is EqualityComparable (20.1.1), " from [lib.alg.search]/4.
</blockquote>

<p>[lib.alg.replace]:</p>

<blockquote>
   <p>
   Remove [lib.alg.replace]/1.
   Replace [lb.alg.replace]/2 with:
   </p>

       <blockquote>
       For every iterator i in the range [first, last) for which *i == value
       or pred(*i) holds perform *i = new_value.
       </blockquote>

   <p>
   Remove the first sentence of /4.
   Replace the beginning of /5 with:
   </p>

       <blockquote>
       For every iterator i in the range [result, result + (last -
       first)), assign to *i either...
       </blockquote>

   <p>(Note the defect here, current text says assign to i, not *i).</p>
</blockquote>

<p>[lib.alg.fill]:</p>

<blockquote>
   <p>
   Remove "Type T is Assignable (23.1), " from /1.
   Replace /2 with:
   </p>

       <blockquote>
       For every iterator i in the range [first, last) or [first, first + n),
       perform *i = value.
       </blockquote>
</blockquote>

<p>[lib.alg.remove]:</p>
<blockquote>
   Remove /1.
   Remove the first sentence of /6.
</blockquote>

<p><b>Rationale:</b></p>
<p>Duplicate of (a subset of) issue <a href="lwg-defects.html#283">283</a>.</p>
<hr>
<a name="486"><h3>486.&nbsp;min/max CopyConstructible requirement is too strict</h3></a><p><b>Section:</b>&nbsp;25.3.7 <a href="lib-algorithms.html#lib.alg.min.max"> [lib.alg.min.max]</a>&nbsp; <b>Status:</b>&nbsp;<a href="lwg-active.html#Dup">Dup</a>&nbsp; <b>Submitter:</b>&nbsp;Dave Abrahams&nbsp; <b>Date:</b>&nbsp;13 Oct 2004</p>
<p>A straightforward implementation of these algorithms does not need to
copy T.</p>
<p><b>Proposed resolution:</b></p>
<p>drop the the words "and CopyConstructible" from paragraphs 1 and 4</p>
<p><b>Rationale:</b></p>
<p>Dup of <a href="lwg-defects.html#281">281</a>.</p>
<p>----- End of document -----</p>
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