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<head><title>C++ Standard Library Defect Report List</title></head>
<body bgcolor="#ffffff" text="#000000">
<table>
<tr>
<td align="left">Doc. no.</td>
<td align="left">N1658=04-0098</td>
</tr>
<tr>
<td align="left">Date:</td>
<td align="left">16 Jul 2004</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@apple.com&gt;</td>
</tr>
</table>
<h1>C++ Standard Library Defect Report List (Revision 31)</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-closed.html">Library Closed Issues List</a></li>
    </ul>
  <p>This document contains only library issues which have been closed
  by the Library Working Group (LWG) after being found to be defects
  in the standard.  That is, issues which have a status of <a href="lwg-active.html#DR">DR</a>, <a href="lwg-active.html#TC">TC</a>, or <a href="lwg-active.html#RR">RR</a>. See the
  <a href="lwg-closed.html">Library Closed Issues List</a> for issues closed as non-defects.  See the
  <a href="lwg-active.html">Library Active Issues List</a> for active issues and more information.  The
  introductory material in that document also applies to this
  document.</p>
<h2>Revision History</h2>
<ul>
<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-active.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-active.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>Defect Reports</h2>
<hr>
<a name="1"><h3>1.&nbsp;C library linkage editing oversight</h3></a><p><b>Section:</b>&nbsp;17.4.2.2 <a href="lib-intro.html#lib.using.linkage"> [lib.using.linkage]</a>&nbsp; <b>Status:</b>&nbsp;<a href="lwg-active.html#TC">TC</a>&nbsp; <b>Submitter:</b>&nbsp;Beman Dawes&nbsp; <b>Date:</b>&nbsp;16 Nov 1997</p>
<p>The change specified in the proposed resolution below did not make
it into the Standard. This change was accepted in principle at the
London meeting, and the exact wording below was accepted at the
Morristown meeting.</p>
<p><b>Proposed resolution:</b></p>
<p>Change 17.4.2.2 <a href="lib-intro.html#lib.using.linkage"> [lib.using.linkage]</a> paragraph 2
from:</p>

<blockquote>
  <p>It is unspecified whether a name from the Standard C library
  declared with external linkage has either extern "C" or
  extern "C++" linkage.</p>
</blockquote>

<p>to:</p>

<blockquote>
  <p>Whether a name from the Standard C library declared with external
  linkage has extern "C" or extern "C++" linkage
  is implementation defined. It is recommended that an implementation
  use extern "C++" linkage for this purpose.</p>
</blockquote>
<hr>
<a name="3"><h3>3.&nbsp;Atexit registration during atexit() call is not described</h3></a><p><b>Section:</b>&nbsp;18.3 <a href="lib-support.html#lib.support.start.term"> [lib.support.start.term]</a>&nbsp; <b>Status:</b>&nbsp;<a href="lwg-active.html#TC">TC</a>&nbsp; <b>Submitter:</b>&nbsp;Steve Clamage&nbsp; <b>Date:</b>&nbsp;12 Dec 1997</p>
<p>We appear not to have covered all the possibilities of
 exit processing with respect to
atexit registration. <br>
<br>
Example 1: (C and C++)</p>

<pre>    #include &lt;stdlib.h&gt;
    void f1() { }
    void f2() { atexit(f1); }
    
    int main()
    {
        atexit(f2); // the only use of f2
        return 0; // for C compatibility
    }</pre>

<p>At program exit, f2 gets called due to its registration in
main. Running f2 causes f1 to be newly registered during the exit
processing. Is this a valid program? If so, what are its
semantics?</p>

<p>
Interestingly, neither the C standard, nor the C++ draft standard nor
the forthcoming C9X Committee Draft says directly whether you can
register a function with atexit during exit processing.</p>

<p>
All 3 standards say that functions are run in reverse order of their
registration. Since f1 is registered last, it ought to be run first,
but by the time it is registered, it is too late to be first.</p>

<p>If the program is valid, the standards are self-contradictory about
its semantics.</p>

<p>Example 2: (C++ only)</p>

<pre>    
    void F() { static T t; } // type T has a destructor

    int main()
    {
        atexit(F); // the only use of F
    }
</pre>

<p>Function F registered with atexit has a local static variable t,
and F is called for the first time during exit processing. A local
static object is initialized the first time control flow passes
through its definition, and all static objects are destroyed during
exit processing. Is the code valid? If so, what are its semantics?</p>

<p>
Section 18.3 "Start and termination" says that if a function
F is registered with atexit before a static object t is initialized, F
will not be called until after t's destructor completes.</p>

<p>
In example 2, function F is registered with atexit before its local
static object O could possibly be initialized. On that basis, it must
not be called by exit processing until after O's destructor
completes. But the destructor cannot be run until after F is called,
since otherwise the object could not be constructed in the first
place.</p>

<p>If the program is valid, the standard is self-contradictory about
its semantics.</p>

<p>I plan to submit Example 1 as a public comment on the C9X CD, with
a recommendation that the results be undefined. (Alternative: make it
unspecified. I don't think it is worthwhile to specify the case where
f1 itself registers additional functions, each of which registers
still more functions.)</p>

<p>I think we should resolve the situation in the whatever way the C
committee decides. </p>

<p>For Example 2, I recommend we declare the results undefined.</p>

<p><i>[See reflector message lib-6500 for further discussion.]</i></p>

<p><b>Proposed resolution:</b></p>
<p>Change section 18.3/8 from:</p>
<blockquote>
  First, objects with static storage duration are destroyed and
  functions registered by calling atexit are called. Objects with
  static storage duration are destroyed in the reverse order of the
  completion of their constructor.  (Automatic objects are not
  destroyed as a result of calling exit().) Functions registered with
  atexit are called in the reverse order of their registration.  A
  function registered with atexit before an object obj1 of static
  storage duration is initialized will not be called until obj1's
  destruction has completed. A function registered with atexit after
  an object obj2 of static storage duration is initialized will be
  called before obj2's destruction starts.
</blockquote>
<p>to:</p>
<blockquote>
  First, objects with static storage duration are destroyed and
  functions registered by calling atexit are called. Non-local objects
  with static storage duration are destroyed in the reverse order of
  the completion of their constructor. (Automatic objects are not
  destroyed as a result of calling exit().) Functions registered with
  atexit are called in the reverse order of their registration, except
  that a function is called after any previously registered functions
  that had already been called at the time it was registered. A
  function registered with atexit before a non-local object obj1 of
  static storage duration is initialized will not be called until
  obj1's destruction has completed. A function registered with atexit
  after a non-local object obj2 of static storage duration is
  initialized will be called before obj2's destruction starts. A local
  static object obj3 is destroyed at the same time it would be if a
  function calling the obj3 destructor were registered with atexit at
  the completion of the obj3 constructor.
</blockquote>
<p><b>Rationale:</b></p>
<p>See 99-0039/N1215, October 22, 1999, by Stephen D. Clamage for the analysis
supporting to the proposed resolution.</p>
<hr>
<a name="5"><h3>5.&nbsp;String::compare specification questionable</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#TC">TC</a>&nbsp; <b>Submitter:</b>&nbsp;Jack Reeves&nbsp; <b>Date:</b>&nbsp;11 Dec 1997</p>
<p>At the very end of the basic_string class definition is the signature: int
compare(size_type pos1, size_type n1, const charT* s, size_type n2 = npos) const; In the
following text this is defined as: returns
basic_string&lt;charT,traits,Allocator&gt;(*this,pos1,n1).compare(
basic_string&lt;charT,traits,Allocator&gt;(s,n2); </p>

<p>Since the constructor basic_string(const charT* s, size_type n, const Allocator&amp; a
= Allocator()) clearly requires that s != NULL and n &lt; npos and further states that it
throws length_error if n == npos, it appears the compare() signature above should always
throw length error if invoked like so: str.compare(1, str.size()-1, s); where 's' is some
null terminated character array. </p>

<p>This appears to be a typo since the obvious intent is to allow either the call above or
something like: str.compare(1, str.size()-1, s, strlen(s)-1); </p>

<p>This would imply that what was really intended was two signatures int compare(size_type
pos1, size_type n1, const charT* s) const int compare(size_type pos1, size_type n1, const
charT* s, size_type n2) const; each defined in terms of the corresponding constructor. </p>
<p><b>Proposed resolution:</b></p>
<p>Replace the compare signature in 21.3 <a href="lib-strings.html#lib.basic.string"> [lib.basic.string]</a>
(at the very end of the basic_string synopsis) which reads:</p>

<blockquote>
  <p><tt>int compare(size_type pos1, size_type n1,<br>
  &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; const charT* s,
  size_type n2 = npos) const;</tt></p>
</blockquote>

<p>with:</p>

<blockquote>
  <p><tt>int compare(size_type pos1, size_type n1,<br>
  &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; const charT* s) const;<br>
  int compare(size_type pos1, size_type n1,<br>
  &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; const charT* s,
  size_type n2) const;</tt></p>
</blockquote>

<p>Replace the portion of 21.3.6.8 <a href="lib-strings.html#lib.string::compare"> [lib.string::compare]</a>
paragraphs 5 and 6 which read:</p>

<blockquote>
  <p><tt>int compare(size_type pos, size_type n1,<br>
  &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; charT * s, size_type n2
  = npos) const;<br>
  </tt>Returns:<tt><br>
  basic_string&lt;charT,traits,Allocator&gt;(*this, pos, n1).compare(<br>
  &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
  basic_string&lt;charT,traits,Allocator&gt;( s, n2))</tt></p>
</blockquote>

<p>with:</p>

<blockquote>
  <p><tt>int compare(size_type pos, size_type n1,<br>
  &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; const charT * s) const;<br>
  </tt>Returns:<tt><br>
  basic_string&lt;charT,traits,Allocator&gt;(*this, pos, n1).compare(<br>
  &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
  basic_string&lt;charT,traits,Allocator&gt;( s ))<br>
  <br>
  int compare(size_type pos, size_type n1,<br>
  &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; const charT * s,
  size_type n2) const;<br>
  </tt>Returns:<tt><br>
  basic_string&lt;charT,traits,Allocator&gt;(*this, pos, n1).compare(<br>
  &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
  basic_string&lt;charT,traits,Allocator&gt;( s, n2))</tt></p>
</blockquote>

<p>Editors please note that in addition to splitting the signature, the third argument
becomes const, matching the existing synopsis.</p>
<p><b>Rationale:</b></p>
<p>While the LWG dislikes adding signatures, this is a clear defect in
the Standard which must be fixed.&nbsp; The same problem was also
identified in issues 7 (item 5) and 87.</p>
<hr>
<a name="7"><h3>7.&nbsp;String clause minor problems</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#TC">TC</a>&nbsp; <b>Submitter:</b>&nbsp;Matt Austern&nbsp; <b>Date:</b>&nbsp;15 Dec 1997</p>
<p>(1) In 21.3.5.4 <a href="lib-strings.html#lib.string::insert"> [lib.string::insert]</a>, the description of template
&lt;class InputIterator&gt; insert(iterator, InputIterator,
InputIterator) makes no sense. It refers to a member function that
doesn't exist. It also talks about the return value of a void
function. </p>

<p>(2) Several versions of basic_string::replace don't appear in the
class synopsis. </p>

<p>(3) basic_string::push_back appears in the synopsis, but is never
described elsewhere.  In the synopsis its argument is const charT,
which doesn't makes much sense; it should probably be charT, or
possible const charT&amp;. </p>

<p>(4) basic_string::pop_back is missing. </p>

<p>(5) int compare(size_type pos, size_type n1, charT* s, size_type n2
= npos) make no sense. First, it's const charT* in the synopsis and
charT* in the description. Second, given what it says in RETURNS,
leaving out the final argument will always result in an exception
getting thrown. This is paragraphs 5 and 6 of 
21.3.6.8 <a href="lib-strings.html#lib.string::compare"> [lib.string::compare]</a></p>

<p>(6) In table 37, in section 21.1.1 <a href="lib-strings.html#lib.char.traits.require"> [lib.char.traits.require]</a>,
there's a note for X::move(s, p, n). It says "Copies correctly
even where p is in [s, s+n)". This is correct as far as it goes,
but it doesn't go far enough; it should also guarantee that the copy
is correct even where s in in [p, p+n). These are two orthogonal
guarantees, and neither one follows from the other. Both guarantees
are necessary if X::move is supposed to have the same sort of
semantics as memmove (which was clearly the intent), and both
guarantees are necessary if X::move is actually supposed to be
useful. </p>
<p><b>Proposed resolution:</b></p>
<p>ITEM 1: In 21.3.5.4 [lib.string::insert], change paragraph 16 to <br>
<br>
&nbsp;&nbsp;&nbsp; EFFECTS: Equivalent to insert(p - begin(), basic_string(first, last)).<br>
<br>
ITEM 2:&nbsp; Not a defect; the Standard is clear.. There are ten versions of replace() in
the synopsis, and ten versions in 21.3.5.6 [lib.string::replace].<br>
<br>
ITEM 3: Change the declaration of push_back in the string synopsis (21.3,
[lib.basic.string]) from:</p>

<p>&nbsp;&nbsp;&nbsp;&nbsp; void push_back(const charT)<br>
<br>
to<br>
<br>
&nbsp;&nbsp;&nbsp;&nbsp; void push_back(charT)<br>
<br>
Add the following text immediately after 21.3.5.2 [lib.string::append], paragraph 10.<br>
<br>
&nbsp;&nbsp;&nbsp; void basic_string::push_back(charT c);<br>
&nbsp;&nbsp;&nbsp; EFFECTS: Equivalent to append(static_cast&lt;size_type&gt;(1), c);<br>
<br>
ITEM 4: Not a defect. The omission appears to have been deliberate.<br>
<br>
ITEM 5: Duplicate; see issue 5 (and 87).<br>
<br>
ITEM 6: In table 37, Replace:<br>
<br>
&nbsp;&nbsp;&nbsp; "Copies correctly even where p is in [s, s+n)."<br>
<br>
with:<br>
<br>
&nbsp;&nbsp;&nbsp;&nbsp; "Copies correctly even where the ranges [p, p+n) and [s,
s+n) overlap."</p>
<hr>
<a name="8"><h3>8.&nbsp;Locale::global lacks guarantee</h3></a><p><b>Section:</b>&nbsp;22.1.1.5 <a href="lib-locales.html#lib.locale.statics"> [lib.locale.statics]</a>&nbsp; <b>Status:</b>&nbsp;<a href="lwg-active.html#TC">TC</a>&nbsp; <b>Submitter:</b>&nbsp;Matt Austern&nbsp; <b>Date:</b>&nbsp;24 Dec 1997</p>
<p>It appears there's an important guarantee missing from clause
22. We're told that invoking locale::global(L) sets the C locale if L
has a name. However, we're not told whether or not invoking
setlocale(s) sets the global C++ locale. </p>

<p>The intent, I think, is that it should not, but I can't find any
such words anywhere. </p>
<p><b>Proposed resolution:</b></p>
<p>Add a sentence at the end of 22.1.1.5 <a href="lib-locales.html#lib.locale.statics"> [lib.locale.statics]</a>,
paragraph 2:&nbsp; </p>

<blockquote>
  <p>No library function other than <tt>locale::global()</tt> shall affect 
  the value returned by <tt>locale()</tt>. </p>

</blockquote>
<hr>
<a name="9"><h3>9.&nbsp;Operator new(0) calls should not yield the same pointer</h3></a><p><b>Section:</b>&nbsp;18.4.1 <a href="lib-support.html#lib.new.delete"> [lib.new.delete]</a>&nbsp; <b>Status:</b>&nbsp;<a href="lwg-active.html#TC">TC</a>&nbsp; <b>Submitter:</b>&nbsp;Steve Clamage&nbsp; <b>Date:</b>&nbsp;4 Jan 1998</p>
<p>Scott Meyers, in a comp.std.c++ posting: I just noticed that
section 3.7.3.1 of CD2 seems to allow for the possibility that all
calls to operator new(0) yield the same pointer, an implementation
technique specifically prohibited by ARM 5.3.3.Was this prohibition
really lifted? Does the FDIS agree with CD2 in the regard? [Issues
list maintainer's note: the IS is the same.]</p>
<p><b>Proposed resolution:</b></p>
<p>Change the last paragraph of 3.7.3 from:</p>
<blockquote>
  <p>Any allocation and/or deallocation functions defined in a C++ program shall
  conform to the semantics specified in 3.7.3.1 and 3.7.3.2.</p>
</blockquote>
<p>to:</p>
<blockquote>
  <p>Any allocation and/or deallocation functions defined in a C++ program,
  including the default versions in the library, shall conform to the semantics
  specified in 3.7.3.1 and 3.7.3.2.</p>
</blockquote>
<p>Change 3.7.3.1/2, next-to-last sentence, from :</p>
<blockquote>
  <p>If the size of the space requested is zero, the value returned shall not be
  a null pointer value (4.10).</p>
</blockquote>
<p>to:</p>
<blockquote>
  <p>Even if the size of the space requested is zero, the request can fail. If
  the request succeeds, the value returned shall be a non-null pointer value
  (4.10) p0 different from any previously returned value p1, unless that value
  p1 was since passed to an operator delete.</p>
</blockquote>
<p>5.3.4/7 currently reads:</p>
<blockquote>
  <p>When the value of the expression in a direct-new-declarator is zero, the
  allocation function is called to allocate an array with no elements. The
  pointer returned by the new-expression is non-null. [Note: If the library
  allocation function is called, the pointer returned is distinct from the
  pointer to any other object.]</p>
</blockquote>
<p>Retain the first sentence, and delete the remainder.</p>
<p>18.4.1 currently has no text. Add the following:</p>
<blockquote>
  <p>Except where otherwise specified, the provisions of 3.7.3 apply to the
  library versions of operator new and operator delete.</p>
</blockquote>
<p>To 18.4.1.3, add the following text:</p>
<blockquote>
  <p>The provisions of 3.7.3 do not apply to these reserved placement forms of
  operator new and operator delete.</p>
</blockquote>
<p><b>Rationale:</b></p>
<p>See 99-0040/N1216, October 22, 1999, by Stephen D. Clamage for the analysis
supporting to the proposed resolution.</p>
<hr>
<a name="11"><h3>11.&nbsp;Bitset minor problems</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#TC">TC</a>&nbsp; <b>Submitter:</b>&nbsp;Matt Austern&nbsp; <b>Date:</b>&nbsp;22 Jan 1998</p>
<p>(1) bitset&lt;&gt;::operator[] is mentioned in the class synopsis (23.3.5), but it is
not documented in 23.3.5.2. </p>

<p>(2) The class synopsis only gives a single signature for bitset&lt;&gt;::operator[],
reference operator[](size_t pos). This doesn't make much sense. It ought to be overloaded
on const. reference operator[](size_t pos); bool operator[](size_t pos) const. </p>

<p>(3) Bitset's stream input function (23.3.5.3) ought to skip all whitespace before
trying to extract 0s and 1s. The standard doesn't explicitly say that, though. This should
go in the Effects clause.</p>
<p><b>Proposed resolution:</b></p>
<p>ITEMS 1 AND 2:<br>
<br>
In the bitset synopsis (23.3.5 <a href="lib-containers.html#lib.template.bitset"> [lib.template.bitset]</a>), 
replace the member function <br>
<br>
<tt>&nbsp;&nbsp;&nbsp; reference operator[](size_t pos);<br>
</tt><br>
with the two member functions<br>
<br>
<tt>&nbsp;&nbsp;&nbsp; bool operator[](size_t pos) const; <br>
&nbsp;&nbsp;&nbsp; reference operator[](size_t pos); <br>
</tt><br>
Add the following text at the end of 23.3.5.2 <a href="lib-containers.html#lib.bitset.members"> [lib.bitset.members]</a>, 
immediately after paragraph 45:</p>

<blockquote>
  <p><tt>bool operator[](size_t pos) const;</tt><br>
  Requires: pos is valid<br>
  Throws: nothing<br>
  Returns: <tt>test(pos)</tt><br>
  <br>
  <tt>bitset&lt;N&gt;::reference operator[](size_t pos);</tt> <br>
  Requires: pos is valid<br>
  Throws: nothing<br>
  Returns: An object of type <tt>bitset&lt;N&gt;::reference</tt> such that <tt>(*this)[pos]
  == this-&gt;test(pos)</tt>, and such that <tt>(*this)[pos] = val</tt> is equivalent to <tt>this-&gt;set(pos,
  val);</tt></p>
</blockquote>
<p><b>Rationale:</b></p>
<p>The LWG believes Item 3 is not a defect. "Formatted
input" implies the desired semantics. See 27.6.1.2 <a href="lib-iostreams.html#lib.istream.formatted"> [lib.istream.formatted]</a>.
</p>
<hr>
<a name="13"><h3>13.&nbsp;Eos refuses to die</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#TC">TC</a>&nbsp; <b>Submitter:</b>&nbsp;William M. Miller&nbsp; <b>Date:</b>&nbsp;3 Mar 1998</p>
<p>In 27.6.1.2.3, there is a reference to "eos", which is
the only one in the whole draft (at least using Acrobat search), so
it's undefined. </p>
<p><b>Proposed resolution:</b></p>
<p>In 27.6.1.2.3 <a href="lib-iostreams.html#lib.istream::extractors"> [lib.istream::extractors]</a>, replace "eos" with
"charT()"</p>
<hr>
<a name="14"><h3>14.&nbsp;Locale::combine should be const</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#TC">TC</a>&nbsp; <b>Submitter:</b>&nbsp;Nathan Myers&nbsp; <b>Date:</b>&nbsp;6 Aug 1998</p>
<p>locale::combine is the only member function of locale (other than constructors and
destructor) that is not const. There is no reason for it not to be const, and good reasons
why it should have been const. Furthermore, leaving it non-const conflicts with 22.1.1
paragraph 6: "An instance of a locale is immutable." </p>

<p>History: this member function originally was a constructor. it happened that the
interface it specified had no corresponding language syntax, so it was changed to a member
function. As constructors are never const, there was no "const" in the interface
which was transformed into member "combine". It should have been added at that
time, but the omission was not noticed. </p>
<p><b>Proposed resolution:</b></p>
<p>In 22.1.1 <a href="lib-locales.html#lib.locale"> [lib.locale]</a> and also in 22.1.1.3 <a href="lib-locales.html#lib.locale.members"> [lib.locale.members]</a>, add 
"const" to the declaration of member combine: </p>
<blockquote>
  <pre>template &lt;class Facet&gt; locale combine(const locale&amp; other) const; </pre>
</blockquote>
<hr>
<a name="15"><h3>15.&nbsp;Locale::name requirement inconsistent</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#TC">TC</a>&nbsp; <b>Submitter:</b>&nbsp;Nathan Myers&nbsp; <b>Date:</b>&nbsp;6 Aug 1998</p>
<p>locale::name() is described as returning a string that can be passed to a locale
constructor, but there is no matching constructor. </p>
<p><b>Proposed resolution:</b></p>
<p>In 22.1.1.3 <a href="lib-locales.html#lib.locale.members"> [lib.locale.members]</a>, paragraph 5, replace
"<tt>locale(name())</tt>" with
"<tt>locale(name().c_str())</tt>".
</p>
<hr>
<a name="16"><h3>16.&nbsp;Bad ctype_byname&lt;char&gt; decl</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#TC">TC</a>&nbsp; <b>Submitter:</b>&nbsp;Nathan Myers&nbsp; <b>Date:</b>&nbsp;6 Aug 1998</p>
<p>The new virtual members ctype_byname&lt;char&gt;::do_widen and do_narrow did not get
edited in properly. Instead, the member do_widen appears four times, with wrong argument
lists. </p>
<p><b>Proposed resolution:</b></p>
<p>The correct declarations for the overloaded members
<tt>do_narrow</tt> and <tt>do_widen</tt> should be copied 
from 22.2.1.3 <a href="lib-locales.html#lib.facet.ctype.special"> [lib.facet.ctype.special]</a>.</p>
<hr>
<a name="17"><h3>17.&nbsp;Bad bool parsing</h3></a><p><b>Section:</b>&nbsp;22.2.2.1.2 <a href="lib-locales.html#lib.facet.num.get.virtuals"> [lib.facet.num.get.virtuals]</a>&nbsp; <b>Status:</b>&nbsp;<a href="lwg-active.html#TC">TC</a>&nbsp; <b>Submitter:</b>&nbsp;Nathan Myers&nbsp; <b>Date:</b>&nbsp;6 Aug 1998</p>
<p>This section describes the process of parsing a text boolean value from the input
stream. It does not say it recognizes either of the sequences "true" or
"false" and returns the corresponding bool value; instead, it says it recognizes
only one of those sequences, and chooses which according to the received value of a
reference argument intended for returning the result, and reports an error if the other
sequence is found. (!) Furthermore, it claims to get the names from the ctype&lt;&gt;
facet rather than the numpunct&lt;&gt; facet, and it examines the "boolalpha"
flag wrongly; it doesn't define the value "loc"; and finally, it computes
wrongly whether to use numeric or "alpha" parsing.<br>
<br>
I believe the correct algorithm is "as if": </p>

<pre>  // in, err, val, and str are arguments.
  err = 0;
  const numpunct&lt;charT&gt;&amp; np = use_facet&lt;numpunct&lt;charT&gt; &gt;(str.getloc());
  const string_type t = np.truename(), f = np.falsename();
  bool tm = true, fm = true;
  size_t pos = 0;
  while (tm &amp;&amp; pos &lt; t.size() || fm &amp;&amp; pos &lt; f.size()) {
    if (in == end) { err = str.eofbit; }
    bool matched = false;
    if (tm &amp;&amp; pos &lt; t.size()) {
      if (!err &amp;&amp; t[pos] == *in) matched = true;
      else tm = false;
    }
    if (fm &amp;&amp; pos &lt; f.size()) {
      if (!err &amp;&amp; f[pos] == *in) matched = true;
      else fm = false;
    }
    if (matched) { ++in; ++pos; }
    if (pos &gt; t.size()) tm = false;
    if (pos &gt; f.size()) fm = false;
  }
  if (tm == fm || pos == 0) { err |= str.failbit; }
  else                      { val = tm; }
  return in;</pre>

<p>Notice this works reasonably when the candidate strings are both empty, or equal, or
when one is a substring of the other. The proposed text below captures the logic of the
code above.</p>
<p><b>Proposed resolution:</b></p>
<p>In 22.2.2.1.2 <a href="lib-locales.html#lib.facet.num.get.virtuals"> [lib.facet.num.get.virtuals]</a>, in the first line of paragraph 14,
change "&amp;&amp;" to "&amp;".</p>

<p>Then, replace paragraphs 15 and 16 as follows:</p>

<blockquote>

  <p>Otherwise target sequences are determined "as if" by
  calling the members <tt>falsename()</tt> and
  <tt>truename()</tt> of the facet obtained by
  <tt>use_facet&lt;numpunct&lt;charT&gt;&nbsp;&gt;(str.getloc())</tt>.  
  Successive characters in the range <tt>[in,end)</tt> (see
  [lib.sequence.reqmts]) are obtained and matched against
  corresponding positions in the target sequences only as necessary to
  identify a unique match. The input iterator <tt>in</tt> is
  compared to <tt>end</tt> only when necessary to obtain a
  character. If and only if a target sequence is uniquely matched,
  <tt>val</tt> is set to the corresponding value.</p>

</blockquote>

<blockquote>
  <p>The <tt>in</tt> iterator is always left pointing one position beyond the last character
  successfully matched. If <tt>val</tt> is set, then err is set to <tt>str.goodbit</tt>; or to
  <tt>str.eofbit</tt> if, when seeking another character to match, it is found that
  <tt>(in==end)</tt>. If <tt>val</tt> is not set, then <i>err</i> is set to <tt>str.failbit</tt>; or to
  <tt>(str.failbit|str.eofbit)</tt>if
  the reason for the failure was that <tt>(in==end)</tt>. [Example: for targets
  <tt>true</tt>:"a" and <tt>false</tt>:"abb", the input sequence "a" yields
  <tt>val==true</tt> and <tt>err==str.eofbit</tt>; the input sequence "abc" yields
  <tt>err=str.failbit</tt>, with <tt>in</tt> ending at the 'c' element. For targets
  <tt>true</tt>:"1"
  and <tt>false</tt>:"0", the input sequence "1" yields <tt>val==true</tt>
  and <tt>err=str.goodbit</tt>. For empty targets (""), any input sequence yields
  <tt>err==str.failbit</tt>. --end example]</p>
</blockquote>
<hr>
<a name="18"><h3>18.&nbsp;Get(...bool&amp;) omitted</h3></a><p><b>Section:</b>&nbsp;22.2.2.1.1 <a href="lib-locales.html#lib.facet.num.get.members"> [lib.facet.num.get.members]</a>&nbsp; <b>Status:</b>&nbsp;<a href="lwg-active.html#TC">TC</a>&nbsp; <b>Submitter:</b>&nbsp;Nathan Myers&nbsp; <b>Date:</b>&nbsp;6 Aug 1998</p>
<p>In the list of num_get&lt;&gt; non-virtual members on page 22-23, the member
that parses bool values was omitted from the list of definitions of non-virtual
members, though it is listed in the class definition and the corresponding
virtual is listed everywhere appropriate. </p>
<p><b>Proposed resolution:</b></p>
<p>Add at the beginning of 22.2.2.1.1 <a href="lib-locales.html#lib.facet.num.get.members"> [lib.facet.num.get.members]</a>
another get member for bool&amp;, copied from the entry in 
22.2.2.1 <a href="lib-locales.html#lib.locale.num.get"> [lib.locale.num.get]</a>.</p>
<hr>
<a name="19"><h3>19.&nbsp;"Noconv" definition too vague</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#TC">TC</a>&nbsp; <b>Submitter:</b>&nbsp;Nathan Myers&nbsp; <b>Date:</b>&nbsp;6 Aug 1998</p>
<p>
In the definitions of codecvt&lt;&gt;::do_out and do_in, they are
specified to return noconv if "no conversion is
needed". This definition is too vague, and does not say
normatively what is done with the buffers.
</p>
<p><b>Proposed resolution:</b></p>
<p>
Change the entry for noconv in the table under paragraph 4 in section 
22.2.1.5.2 <a href="lib-locales.html#lib.locale.codecvt.virtuals"> [lib.locale.codecvt.virtuals]</a> to read:
</p>
<blockquote>
  <p><tt>noconv</tt>: <tt>internT</tt> and <tt>externT</tt> are the same type,
  and input sequence is identical to converted sequence.</p>
</blockquote>
<p>Change the Note in paragraph 2 to normative text as follows:</p>
<blockquote>
  <p>If returns <tt>noconv</tt>, <tt>internT</tt> and <tt>externT</tt> are the
  same type and the converted sequence is identical to the input sequence <tt>[from,from_next)</tt>.
  <tt>to_next</tt> is set equal to <tt>to</tt>, the value of <tt>state</tt> is
  unchanged, and there are no changes to the values in <tt>[to, to_limit)</tt>.</p>
</blockquote>
<hr>
<a name="20"><h3>20.&nbsp;Thousands_sep returns wrong type</h3></a><p><b>Section:</b>&nbsp;22.2.3.1.2 <a href="lib-locales.html#lib.facet.numpunct.virtuals"> [lib.facet.numpunct.virtuals]</a>&nbsp; <b>Status:</b>&nbsp;<a href="lwg-active.html#TC">TC</a>&nbsp; <b>Submitter:</b>&nbsp;Nathan Myers&nbsp; <b>Date:</b>&nbsp;6 Aug 1998</p>
<p>The synopsis for numpunct&lt;&gt;::do_thousands_sep, and the
definition of numpunct&lt;&gt;::thousands_sep which calls it, specify
that it returns a value of type char_type. Here it is erroneously
described as returning a "string_type". </p>
<p><b>Proposed resolution:</b></p>
<p>In 22.2.3.1.2 <a href="lib-locales.html#lib.facet.numpunct.virtuals"> [lib.facet.numpunct.virtuals]</a>, above paragraph 2, change 
"string_type" to "char_type". </p>
<hr>
<a name="21"><h3>21.&nbsp;Codecvt_byname&lt;&gt; instantiations</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#TC">TC</a>&nbsp; <b>Submitter:</b>&nbsp;Nathan Myers&nbsp; <b>Date:</b>&nbsp;6 Aug 1998</p>
<p>In the second table in the section, captioned "Required
instantiations", the instantiations for codecvt_byname&lt;&gt;
have been omitted. These are necessary to allow users to construct a
locale by name from facets. </p>
<p><b>Proposed resolution:</b></p>
<p>Add in 22.1.1.1.1 <a href="lib-locales.html#lib.locale.category"> [lib.locale.category]</a> to the table captioned
"Required instantiations", in the category "ctype"
the lines </p>

<blockquote>
  <pre>codecvt_byname&lt;char,char,mbstate_t&gt;,
codecvt_byname&lt;wchar_t,char,mbstate_t&gt; </pre>
</blockquote>
<hr>
<a name="22"><h3>22.&nbsp;Member open vs. flags</h3></a><p><b>Section:</b>&nbsp;27.8.1.7 <a href="lib-iostreams.html#lib.ifstream.members"> [lib.ifstream.members]</a>&nbsp; <b>Status:</b>&nbsp;<a href="lwg-active.html#TC">TC</a>&nbsp; <b>Submitter:</b>&nbsp;Nathan Myers&nbsp; <b>Date:</b>&nbsp;6 Aug 1998</p>
<p>The description of basic_istream&lt;&gt;::open leaves unanswered questions about how it
responds to or changes flags in the error status for the stream. A strict reading
indicates that it ignores the bits and does not change them, which confuses users who do
not expect eofbit and failbit to remain set after a successful open. There are three
reasonable resolutions: 1) status quo 2) fail if fail(), ignore eofbit 3) clear failbit
and eofbit on call to open(). </p>
<p><b>Proposed resolution:</b></p>
<p>In 27.8.1.7 <a href="lib-iostreams.html#lib.ifstream.members"> [lib.ifstream.members]</a> paragraph 3, <i>and</i> in 27.8.1.10 <a href="lib-iostreams.html#lib.ofstream.members"> [lib.ofstream.members]</a> paragraph 3, under open() effects, add a footnote:
</p>

<blockquote>
  <p>A successful open does not change the error state.</p>
</blockquote>
<p><b>Rationale:</b></p>
<p>This may seem surprising to some users, but it's just an instance
of a general rule: error flags are never cleared by the
implementation. The only way error flags are are ever cleared is if
the user explicitly clears them by hand.</p>

<p>The LWG believed that preserving this general rule was
important enough so that an exception shouldn't be made just for this
one case.  The resolution of this issue clarifies what the LWG
believes to have been the original intent.</p>

<hr>
<a name="24"><h3>24.&nbsp;"do_convert" doesn't exist</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#TC">TC</a>&nbsp; <b>Submitter:</b>&nbsp;Nathan Myers&nbsp; <b>Date:</b>&nbsp;6 Aug 1998</p>
<p>The description of codecvt&lt;&gt;::do_out and do_in mentions a
symbol "do_convert" which is not defined in the
standard. This is a leftover from an edit, and should be "do_in
and do_out". </p>
<p><b>Proposed resolution:</b></p>
<p>In 22.2.1.5 <a href="lib-locales.html#lib.locale.codecvt"> [lib.locale.codecvt]</a>, paragraph 3, change
"do_convert" to "do_in or do_out". Also, in 22.2.1.5.2 <a href="lib-locales.html#lib.locale.codecvt.virtuals"> [lib.locale.codecvt.virtuals]</a>, change "do_convert()" to "do_in
or do_out". </p>
<hr>
<a name="25"><h3>25.&nbsp;String operator&lt;&lt; uses width() value wrong</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#TC">TC</a>&nbsp; <b>Submitter:</b>&nbsp;Nathan Myers&nbsp; <b>Date:</b>&nbsp;6 Aug 1998</p>
<p>In the description of operator&lt;&lt; applied to strings, the standard says that uses
the smaller of os.width() and str.size(), to pad "as described in stage 3"
elsewhere; but this is inconsistent, as this allows no possibility of space for padding. </p>
<p><b>Proposed resolution:</b></p>
<p>Change 21.3.7.9 <a href="lib-strings.html#lib.string.io"> [lib.string.io]</a>  paragraph 4 from:<br>
<br>
&nbsp;&nbsp;&nbsp; "... where <tt>n</tt> is the smaller of <tt>os.width()</tt> and <tt>str.size()</tt>;
..."<br>
<br>
to: <br>
<br>
&nbsp;&nbsp;&nbsp; "... where <tt>n</tt> is the larger of <tt>os.width()</tt> and <tt>str.size()</tt>;
..."</p>
<hr>
<a name="26"><h3>26.&nbsp;Bad sentry example</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#TC">TC</a>&nbsp; <b>Submitter:</b>&nbsp;Nathan Myers&nbsp; <b>Date:</b>&nbsp;6 Aug 1998</p>
<p>In paragraph 6, the code in the example: </p>

<pre>  template &lt;class charT, class traits = char_traits&lt;charT&gt; &gt;
  basic_istream&lt;charT,traits&gt;::sentry(
           basic_istream&lt;charT,traits&gt;&amp; is, bool noskipws = false) {
      ...
      int_type c;
      typedef ctype&lt;charT&gt; ctype_type;
      const ctype_type&amp; ctype = use_facet&lt;ctype_type&gt;(is.getloc());
      while ((c = is.rdbuf()-&gt;snextc()) != traits::eof()) {
        if (ctype.is(ctype.space,c)==0) {
          is.rdbuf()-&gt;sputbackc (c);
          break;
        }
      }
      ...
   }</pre>

<p>fails to demonstrate correct use of the facilities described. In
particular, it fails to use traits operators, and specifies incorrect
semantics. (E.g. it specifies skipping over the first character in the
sequence without examining it.) </p>
<p><b>Proposed resolution:</b></p>
<p>Remove the example above from 27.6.1.1.2 <a href="lib-iostreams.html#lib.istream::sentry"> [lib.istream::sentry]</a>
paragraph 6.</p>
<p><b>Rationale:</b></p>
<p>The originally proposed replacement code for the example was not
correct. The LWG tried in Kona and again in Tokyo to correct it
without success. In Tokyo, an implementor reported that actual working
code ran over one page in length and was quite complicated. The LWG
decided that it would be counter-productive to include such a lengthy
example, which might well still contain errors.</p>
<hr>
<a name="27"><h3>27.&nbsp;String::erase(range) yields wrong iterator</h3></a><p><b>Section:</b>&nbsp;21.3.5.5 <a href="lib-strings.html#lib.string::erase"> [lib.string::erase]</a>&nbsp; <b>Status:</b>&nbsp;<a href="lwg-active.html#TC">TC</a>&nbsp; <b>Submitter:</b>&nbsp;Nathan Myers&nbsp; <b>Date:</b>&nbsp;6 Aug 1998</p>
<p>The string::erase(iterator first, iterator last) is specified to return an element one
place beyond the next element after the last one erased. E.g. for the string
"abcde", erasing the range ['b'..'d') would yield an iterator for element 'e',
while 'd' has not been erased. </p>
<p><b>Proposed resolution:</b></p>
<p>In 21.3.5.5 <a href="lib-strings.html#lib.string::erase"> [lib.string::erase]</a>, paragraph 10, change: </p>

<blockquote>
  <p>Returns: an iterator which points to the element immediately following _last_ prior to
  the element being erased. </p>
</blockquote>

<p>to read </p>

<blockquote>
  <p>Returns: an iterator which points to the element pointed to by _last_ prior to the
  other elements being erased. </p>
</blockquote>
<hr>
<a name="28"><h3>28.&nbsp;Ctype&lt;char&gt;is ambiguous</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#TC">TC</a>&nbsp; <b>Submitter:</b>&nbsp;Nathan Myers&nbsp; <b>Date:</b>&nbsp;6 Aug 1998</p>
<p>The description of the vector form of ctype&lt;char&gt;::is can be interpreted to mean
something very different from what was intended. Paragraph 4 says </p>

<blockquote>
  <p>Effects: The second form, for all *p in the range [low, high), assigns vec[p-low] to
  table()[(unsigned char)*p]. </p>
</blockquote>

<p>This is intended to copy the value indexed from table()[] into the place identified in
vec[]. </p>
<p><b>Proposed resolution:</b></p>
<p>Change 22.2.1.3.2 <a href="lib-locales.html#lib.facet.ctype.char.members"> [lib.facet.ctype.char.members]</a>, paragraph 4, to read </p>

<blockquote>
  <p>Effects: The second form, for all *p in the range [low, high), assigns into vec[p-low]
  the value table()[(unsigned char)*p]. </p>
</blockquote>
<hr>
<a name="29"><h3>29.&nbsp;Ios_base::init doesn't exist</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#TC">TC</a>&nbsp; <b>Submitter:</b>&nbsp;Nathan Myers&nbsp; <b>Date:</b>&nbsp;6 Aug 1998</p>
<p>Sections 27.3.1 <a href="lib-iostreams.html#lib.narrow.stream.objects"> [lib.narrow.stream.objects]</a> and 27.3.2 <a href="lib-iostreams.html#lib.wide.stream.objects"> [lib.wide.stream.objects]</a> mention
a function ios_base::init, which is not defined. Probably they mean
basic_ios&lt;&gt;::init, defined in 27.4.4.1 <a href="lib-iostreams.html#lib.basic.ios.cons"> [lib.basic.ios.cons]</a>,
paragraph 3. </p>
<p><b>Proposed resolution:</b></p>
<p>[R12: modified to include paragraph 5.]</p>

<p>In 27.3.1 <a href="lib-iostreams.html#lib.narrow.stream.objects"> [lib.narrow.stream.objects]</a> paragraph 2 and 5, change </p>

<blockquote>
  <p>ios_base::init </p>
</blockquote>

<p>to </p>

<blockquote>
  <p>basic_ios&lt;char&gt;::init </p>
</blockquote>

<p>Also, make a similar change in 27.3.2 <a href="lib-iostreams.html#lib.wide.stream.objects"> [lib.wide.stream.objects]</a> except it
should read </p>

<blockquote>
  <p>basic_ios&lt;wchar_t&gt;::init </p>
</blockquote>
<hr>
<a name="30"><h3>30.&nbsp;Wrong header for LC_*</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#TC">TC</a>&nbsp; <b>Submitter:</b>&nbsp;Nathan Myers&nbsp; <b>Date:</b>&nbsp;6 Aug 1998</p>
<p>Paragraph 2 implies that the C macros LC_CTYPE etc. are defined in &lt;cctype&gt;,
where they are in fact defined elsewhere to appear in &lt;clocale&gt;. </p>
<p><b>Proposed resolution:</b></p>
<p>In 22.1.1.1.1 <a href="lib-locales.html#lib.locale.category"> [lib.locale.category]</a>, paragraph 2, change
"&lt;cctype&gt;" to read "&lt;clocale&gt;". </p>
<hr>
<a name="31"><h3>31.&nbsp;Immutable locale values</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#TC">TC</a>&nbsp; <b>Submitter:</b>&nbsp;Nathan Myers&nbsp; <b>Date:</b>&nbsp;6 Aug 1998</p>
<p>Paragraph 6, says "An instance of <tt>locale</tt> is
<i>immutable</i>; once a facet reference is obtained from it,
...". This has caused some confusion, because locale variables
are manifestly assignable. </p>
<p><b>Proposed resolution:</b></p>
<p>In 22.1.1 <a href="lib-locales.html#lib.locale"> [lib.locale]</a> replace paragraph 6</p>

<blockquote>
  <p>An instance of <tt>locale</tt> is immutable; once a facet
  reference is obtained from it, that reference remains usable as long
  as the locale value itself exists.</p>
</blockquote>

<p>with</p>

<blockquote>
  <p>Once a facet reference is obtained from a locale object by
  calling use_facet&lt;&gt;, that reference remains usable, and the
  results from member functions of it may be cached and re-used, as
  long as some locale object refers to that facet.</p>
</blockquote>
<hr>
<a name="32"><h3>32.&nbsp;Pbackfail description inconsistent</h3></a><p><b>Section:</b>&nbsp;27.5.2.4.4 <a href="lib-iostreams.html#lib.streambuf.virt.pback"> [lib.streambuf.virt.pback]</a>&nbsp; <b>Status:</b>&nbsp;<a href="lwg-active.html#TC">TC</a>&nbsp; <b>Submitter:</b>&nbsp;Nathan Myers&nbsp; <b>Date:</b>&nbsp;6 Aug 1998</p>
<p>The description of the required state before calling virtual member
basic_streambuf&lt;&gt;::pbackfail requirements is inconsistent with the conditions
described in 27.5.2.2.4 [lib.streambuf.pub.pback] where member sputbackc calls it.
Specifically, the latter says it calls pbackfail if: </p>

<p>&nbsp;&nbsp;&nbsp; traits::eq(c,gptr()[-1]) is false </p>

<p>where pbackfail claims to require: </p>

<p>&nbsp;&nbsp;&nbsp; traits::eq(*gptr(),traits::to_char_type(c)) returns false </p>

<p>It appears that the pbackfail description is wrong. </p>
<p><b>Proposed resolution:</b></p>
<p>In 27.5.2.4.4 <a href="lib-iostreams.html#lib.streambuf.virt.pback"> [lib.streambuf.virt.pback]</a>, paragraph 1, change:</p>

<blockquote>
  <p>"<tt>traits::eq(*gptr(),traits::to_char_type( c))</tt>"</p>
</blockquote>

<p>to </p>

<blockquote>
  <p>"<tt>traits::eq(traits::to_char_type(c),gptr()[-1])</tt>"
  </p>
</blockquote>
<p><b>Rationale:</b></p>
<p>Note deliberate reordering of arguments for clarity in addition to the correction of
the argument value.</p>
<hr>
<a name="33"><h3>33.&nbsp;Codecvt&lt;&gt; mentions from_type</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#TC">TC</a>&nbsp; <b>Submitter:</b>&nbsp;Nathan Myers&nbsp; <b>Date:</b>&nbsp;6 Aug 1998</p>
<p>In the table defining the results from do_out and do_in, the specification for the
result <i>error</i> says </p>

<blockquote>
  <p>encountered a from_type character it could not convert </p>
</blockquote>

<p>but from_type is not defined. This clearly is intended to be an externT for do_in, or
an internT for do_out. </p>
<p><b>Proposed resolution:</b></p>
<p>In 22.2.1.5.2 <a href="lib-locales.html#lib.locale.codecvt.virtuals"> [lib.locale.codecvt.virtuals]</a> paragraph 4, replace the definition
in the table for the case of _error_ with </p>

<blockquote>
  <p>encountered a character in <tt>[from,from_end)</tt> that it could not convert. </p>
</blockquote>
<hr>
<a name="34"><h3>34.&nbsp;True/falsename() not in ctype&lt;&gt;</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#TC">TC</a>&nbsp; <b>Submitter:</b>&nbsp;Nathan Myers&nbsp; <b>Date:</b>&nbsp;6 Aug 1998</p>
<p>In paragraph 19, Effects:, members truename() and falsename are used from facet
ctype&lt;charT&gt;, but it has no such members. Note that this is also a problem in
22.2.2.1.2, addressed in (4). </p>
<p><b>Proposed resolution:</b></p>
<p>In 22.2.2.2.2 <a href="lib-locales.html#lib.facet.num.put.virtuals"> [lib.facet.num.put.virtuals]</a>, paragraph 19, in the Effects:
clause for member put(...., bool), replace the initialization of the
string_type value s as follows: </p>

<blockquote>
  <pre>const numpunct&amp; np = use_facet&lt;numpunct&lt;charT&gt; &gt;(loc);
string_type s = val ? np.truename() : np.falsename(); </pre>
</blockquote>
<hr>
<a name="35"><h3>35.&nbsp;No manipulator unitbuf in synopsis</h3></a><p><b>Section:</b>&nbsp;27.4 <a href="lib-iostreams.html#lib.iostreams.base"> [lib.iostreams.base]</a>&nbsp; <b>Status:</b>&nbsp;<a href="lwg-active.html#TC">TC</a>&nbsp; <b>Submitter:</b>&nbsp;Nathan Myers&nbsp; <b>Date:</b>&nbsp;6 Aug 1998</p>
<p>In 27.4.5.1 <a href="lib-iostreams.html#lib.fmtflags.manip"> [lib.fmtflags.manip]</a>, we have a definition for a manipulator
named "unitbuf". Unlike other manipulators, it's not listed
in synopsis. Similarly for "nounitbuf". </p>
<p><b>Proposed resolution:</b></p>
<p>Add to the synopsis for &lt;ios&gt; in 27.4 <a href="lib-iostreams.html#lib.iostreams.base"> [lib.iostreams.base]</a>, after
the entry for "nouppercase", the prototypes: </p>

<blockquote>
  <pre>ios_base&amp; unitbuf(ios_base&amp; str);
ios_base&amp; nounitbuf(ios_base&amp; str); </pre>
</blockquote>
<hr>
<a name="36"><h3>36.&nbsp;Iword &amp; pword storage lifetime omitted</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#TC">TC</a>&nbsp; <b>Submitter:</b>&nbsp;Nathan Myers&nbsp; <b>Date:</b>&nbsp;6 Aug 1998</p>
<p>In the definitions for ios_base::iword and pword, the lifetime of the storage is
specified badly, so that an implementation which only keeps the last value stored appears
to conform. In particular, it says: </p>

<p>The reference returned may become invalid after another call to the object's iword
member with a different index ... </p>

<p>This is not idle speculation; at least one implementation was done this way. </p>
<p><b>Proposed resolution:</b></p>
<p>Add in 27.4.2.5 <a href="lib-iostreams.html#lib.ios.base.storage"> [lib.ios.base.storage]</a>, in both paragraph 2 and also in
paragraph 4, replace the sentence: </p>

<blockquote>
  <p>The reference returned may become invalid after another call to the object's iword
  [pword] member with a different index, after a call to its copyfmt member, or when the
  object is destroyed. </p>
</blockquote>

<p>with: </p>

<blockquote>
  <p>The reference returned is invalid after any other operations on the object. However,
  the value of the storage referred to is retained, so that until the next call to copyfmt,
  calling iword [pword] with the same index yields another reference to the same value. </p>
</blockquote>

<p>substituting "iword" or "pword" as appropriate. </p>
<hr>
<a name="37"><h3>37.&nbsp;Leftover "global" reference</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#TC">TC</a>&nbsp; <b>Submitter:</b>&nbsp;Nathan Myers&nbsp; <b>Date:</b>&nbsp;6 Aug 1998</p>
<p>In the overview of locale semantics, paragraph 4, is the sentence </p>

<blockquote>
  <p>If Facet is not present in a locale (or, failing that, in the global locale), it throws
  the standard exception bad_cast. </p>
</blockquote>

<p>This is not supported by the definition of use_facet&lt;&gt;, and represents semantics
from an old draft. </p>
<p><b>Proposed resolution:</b></p>
<p>In 22.1.1 <a href="lib-locales.html#lib.locale"> [lib.locale]</a>, paragraph 4, delete the parenthesized
expression </p>

<blockquote>
  <p>(or, failing that, in the global locale) </p>
</blockquote>
<hr>
<a name="38"><h3>38.&nbsp;Facet definition incomplete</h3></a><p><b>Section:</b>&nbsp;22.1.2 <a href="lib-locales.html#lib.locale.global.templates"> [lib.locale.global.templates]</a>&nbsp; <b>Status:</b>&nbsp;<a href="lwg-active.html#TC">TC</a>&nbsp; <b>Submitter:</b>&nbsp;Nathan Myers&nbsp; <b>Date:</b>&nbsp;6 Aug 1998</p>
<p>It has been noticed by Esa Pulkkinen that the definition of
"facet" is incomplete. In particular, a class derived from
another facet, but which does not define a member <i>id</i>, cannot
safely serve as the argument <i>F</i> to use_facet&lt;F&gt;(loc),
because there is no guarantee that a reference to the facet instance
stored in <i>loc</i> is safely convertible to <i>F</i>. </p>
<p><b>Proposed resolution:</b></p>
<p>In the definition of std::use_facet&lt;&gt;(), replace the text in paragraph 1 which
reads: </p>

<blockquote>
  <p>Get a reference to a facet of a locale. </p>
</blockquote>

<p>with: </p>

<blockquote>
  <p>Requires: <tt>Facet</tt> is a facet class whose definition
  contains the public static member <tt>id</tt> as defined in 22.1.1.1.2 <a href="lib-locales.html#lib.locale.facet"> [lib.locale.facet]</a>. </p>
</blockquote>

<p><i>[
Kona: strike as overspecification the text "(not inherits)"
from the original resolution, which read "... whose definition
contains (not inherits) the public static member
<tt>id</tt>..."
]</i></p>

<hr>
<a name="39"><h3>39.&nbsp;istreambuf_iterator&lt;&gt;::operator++(int) definition garbled</h3></a><p><b>Section:</b>&nbsp;24.5.3.4 <a href="lib-iterators.html#lib.istreambuf.iterator::op++"> [lib.istreambuf.iterator::op++]</a>&nbsp; <b>Status:</b>&nbsp;<a href="lwg-active.html#TC">TC</a>&nbsp; <b>Submitter:</b>&nbsp;Nathan Myers&nbsp; <b>Date:</b>&nbsp;6 Aug 1998</p>
<p>Following the definition of istreambuf_iterator&lt;&gt;::operator++(int) in paragraph
3, the standard contains three lines of garbage text left over from a previous edit. </p>

<blockquote>
  <pre>istreambuf_iterator&lt;charT,traits&gt; tmp = *this;
sbuf_-&gt;sbumpc();
return(tmp); </pre>
</blockquote>
<p><b>Proposed resolution:</b></p>
<p>In 24.5.3.4 <a href="lib-iterators.html#lib.istreambuf.iterator::op++"> [lib.istreambuf.iterator::op++]</a>, delete the three lines of code at the
end of paragraph 3. </p>
<hr>
<a name="40"><h3>40.&nbsp;Meaningless normative paragraph in examples</h3></a><p><b>Section:</b>&nbsp;22.2.8 <a href="lib-locales.html#lib.facets.examples"> [lib.facets.examples]</a>&nbsp; <b>Status:</b>&nbsp;<a href="lwg-active.html#TC">TC</a>&nbsp; <b>Submitter:</b>&nbsp;Nathan Myers&nbsp; <b>Date:</b>&nbsp;6 Aug 1998</p>
<p>Paragraph 3 of the locale examples is a description of part of an
implementation technique that has lost its referent, and doesn't mean
anything. </p>
<p><b>Proposed resolution:</b></p>
<p>Delete 22.2.8 <a href="lib-locales.html#lib.facets.examples"> [lib.facets.examples]</a> paragraph 3 which begins "This
initialization/identification system depends...", or (at the
editor's option) replace it with a place-holder to keep the paragraph
numbering the same. </p>
<hr>
<a name="41"><h3>41.&nbsp;Ios_base needs clear(), exceptions()</h3></a><p><b>Section:</b>&nbsp;27.4.2 <a href="lib-iostreams.html#lib.ios.base"> [lib.ios.base]</a>&nbsp; <b>Status:</b>&nbsp;<a href="lwg-active.html#TC">TC</a>&nbsp; <b>Submitter:</b>&nbsp;Nathan Myers&nbsp; <b>Date:</b>&nbsp;6 Aug 1998</p>
<p>The description of ios_base::iword() and pword() in 27.4.2.4 <a href="lib-iostreams.html#lib.ios.members.static"> [lib.ios.members.static]</a>, say that if they fail, they "set badbit,
which may throw an exception". However, ios_base offers no
interface to set or to test badbit; those interfaces are defined in
basic_ios&lt;&gt;. </p>
<p><b>Proposed resolution:</b></p>
<p>Change the description in 27.4.2.5 <a href="lib-iostreams.html#lib.ios.base.storage"> [lib.ios.base.storage]</a> in
paragraph 2, and also in paragraph 4, as follows. Replace</p>

<blockquote>
  <p>If the function fails it sets badbit, which may throw an exception.</p>
</blockquote>

<p>with</p>

<blockquote>
  <p>If the function fails, and <tt>*this</tt> is a base sub-object of
  a <tt>basic_ios&lt;&gt;</tt> object or sub-object, the effect is
  equivalent to calling <tt>basic_ios&lt;&gt;::setstate(badbit)</tt>
  on the derived object (which may throw <tt>failure</tt>).</p>
</blockquote>

<p><i>[Kona: LWG reviewed wording; setstate(failbit) changed to
setstate(badbit).]</i></p>

<hr>
<a name="42"><h3>42.&nbsp;String ctors specify wrong default allocator</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#TC">TC</a>&nbsp; <b>Submitter:</b>&nbsp;Nathan Myers&nbsp; <b>Date:</b>&nbsp;6 Aug 1998</p>
<p>The basic_string&lt;&gt; copy constructor: </p>

<pre>basic_string(const basic_string&amp; str, size_type pos = 0,
             size_type n = npos, const Allocator&amp; a = Allocator()); </pre>

<p>specifies an Allocator argument default value that is
counter-intuitive. The natural choice for a the allocator to copy from
is str.get_allocator(). Though this cannot be expressed in
default-argument notation, overloading suffices. </p>

<p>Alternatively, the other containers in Clause 23 (deque, list,
vector) do not have this form of constructor, so it is inconsistent,
and an evident source of confusion, for basic_string&lt;&gt; to have
it, so it might better be removed. </p>
<p><b>Proposed resolution:</b></p>
<p> In 21.3 <a href="lib-strings.html#lib.basic.string"> [lib.basic.string]</a>, replace the declaration of the copy
constructor as follows: </p>

<blockquote>
  <pre>basic_string(const basic_string&amp; str);
basic_string(const basic_string&amp; str, size_type pos, size_type n = npos,
             const Allocator&amp; a = Allocator());</pre>
</blockquote>

<p>In 21.3.1 <a href="lib-strings.html#lib.string.cons"> [lib.string.cons]</a>, replace the copy constructor declaration
as above. Add to paragraph 5, Effects:</p>

<blockquote>
  <p>In the first form, the Allocator value used is copied from
  <tt>str.get_allocator()</tt>.</p>
</blockquote>
<p><b>Rationale:</b></p>
<p>The LWG believes the constructor is actually broken, rather than
just an unfortunate design choice.</p>

<p>The LWG considered two other possible resolutions:</p>

<p>A. In 21.3 <a href="lib-strings.html#lib.basic.string"> [lib.basic.string]</a>, replace the declaration of the copy
constructor as follows:</p>

<blockquote>
  <pre>basic_string(const basic_string&amp; str, size_type pos = 0,
             size_type n = npos);
basic_string(const basic_string&amp; str, size_type pos,
             size_type n, const Allocator&amp; a); </pre>
</blockquote>

<p>In 21.3.1 <a href="lib-strings.html#lib.string.cons"> [lib.string.cons]</a>, replace the copy constructor declaration
as above. Add to paragraph 5, Effects: </p>

<blockquote>
  <p>When no <tt>Allocator</tt> argument is provided, the string is constructed using the
  value <tt>str.get_allocator()</tt>. </p>
</blockquote>

<p>B. In 21.3 <a href="lib-strings.html#lib.basic.string"> [lib.basic.string]</a>, and also in 21.3.1 <a href="lib-strings.html#lib.string.cons"> [lib.string.cons]</a>, replace
the declaration of the copy constructor as follows: </p>

<blockquote>
  <pre>basic_string(const basic_string&amp; str, size_type pos = 0,
             size_type n = npos); </pre>
</blockquote>

<p>The proposed resolution reflects the original intent of the LWG. It
was also noted by Pete Becker that this fix "will cause
a small amount of existing code to now work correctly."</p>

<p><i>[
Kona: issue editing snafu fixed - the proposed resolution now correctly
reflects the LWG consensus.
]</i></p>
<hr>
<a name="44"><h3>44.&nbsp;Iostreams use operator== on int_type values</h3></a><p><b>Section:</b>&nbsp;27 <a href="lib-iostreams.html#lib.input.output"> [lib.input.output]</a>&nbsp; <b>Status:</b>&nbsp;<a href="lwg-active.html#WP">WP</a>&nbsp; <b>Submitter:</b>&nbsp;Nathan Myers&nbsp; <b>Date:</b>&nbsp;6 Aug 1998</p>
<p>Many of the specifications for iostreams specify that character
values or their int_type equivalents are compared using operators ==
or !=, though in other places traits::eq() or traits::eq_int_type is
specified to be used throughout. This is an inconsistency; we should
change uses of == and != to use the traits members instead. </p>
<p><b>Proposed resolution:</b></p>

<p><i>[Pre-Kona: Dietmar supplied wording]</i></p>

<p>List of changes to clause 27:</p>
<ol>
<li>
   In lib.basic.ios.members paragraph 13 (postcondition clause for
   'fill(cT)') change

<blockquote>
     fillch == fill()
</blockquote>

   to

<blockquote>
     traits::eq(fillch, fill())
</blockquote>


</li>
<li>
   In lib.istream.unformatted paragraph 7 (effects clause for
   'get(cT,streamsize,cT)'), third bullet, change

<blockquote>
     c == delim for the next available input character c
</blockquote>

   to

<blockquote>
     traits::eq(c, delim) for the next available input character c
  </blockquote>

</li>
<li>
   In lib.istream.unformatted paragraph 12 (effects clause for
   'get(basic_streambuf&lt;cT,Tr&gt;&amp;,cT)'), third bullet, change

<blockquote>
     c == delim for the next available input character c
</blockquote>

   to

<blockquote>
     traits::eq(c, delim) for the next available input character c
</blockquote>

</li>
<li>
   In lib.istream.unformatted paragraph 17 (effects clause for
   'getline(cT,streamsize,cT)'), second bullet, change

<blockquote>
     c == delim for the next available input character c
</blockquote>

   to

<blockquote>
     traits::eq(c, delim) for the next available input character c
  </blockquote>

</li>
<li>
   In lib.istream.unformatted paragraph 24 (effects clause for
   'ignore(int,int_type)'), second bullet, change

<blockquote>
     c == delim for the next available input character c
</blockquote>

   to

<blockquote>
     traits::eq_int_type(c, delim) for the next available input
     character c
</blockquote>
  
</li>
<li>
   In lib.istream.unformatted paragraph 25 (notes clause for
   'ignore(int,int_type)'), second bullet, change

<blockquote>
     The last condition will never occur if delim == traits::eof()
</blockquote>

   to

<blockquote>
     The last condition will never occur if
     traits::eq_int_type(delim, traits::eof()).
</blockquote>

</li>
<li>
   In lib.istream.sentry paragraph 6 (example implementation for the
   sentry constructor) change

<blockquote>
     while ((c = is.rdbuf()-&gt;snextc()) != traits::eof()) {
</blockquote>

   to

<blockquote>
     while (!traits::eq_int_type(c = is.rdbuf()-&gt;snextc(), traits::eof())) {
</blockquote>

</li>
</ol>

<p>List of changes to Chapter 21:</p>

<ol>
<li>
   In lib.string::find paragraph 1 (effects clause for find()),
   second bullet, change

<blockquote>
     at(xpos+I) == str.at(I) for all elements ...
</blockquote>

   to

<blockquote>
     traits::eq(at(xpos+I), str.at(I)) for all elements ...
</blockquote>

</li>
<li>
   In lib.string::rfind paragraph 1 (effects clause for rfind()),
   second bullet, change

<blockquote>
     at(xpos+I) == str.at(I) for all elements ...
</blockquote>

   to

<blockquote>
     traits::eq(at(xpos+I), str.at(I)) for all elements ...
</blockquote>

</li>
<li>
   In lib.string::find.first.of paragraph 1 (effects clause for
   find_first_of()), second bullet, change

<blockquote>
     at(xpos+I) == str.at(I) for all elements ...
</blockquote>

   to

<blockquote>
     traits::eq(at(xpos+I), str.at(I)) for all elements ...
</blockquote>

</li>
<li>
   In lib.string::find.last.of paragraph 1 (effects clause for
   find_last_of()), second bullet, change

<blockquote>
     at(xpos+I) == str.at(I) for all elements ...
</blockquote>

   to

<blockquote>
     traits::eq(at(xpos+I), str.at(I)) for all elements ...
</blockquote>

</li>
<li>
   In lib.string::find.first.not.of paragraph 1 (effects clause for
   find_first_not_of()), second bullet, change

<blockquote>
     at(xpos+I) == str.at(I) for all elements ...
</blockquote>

   to

<blockquote>
     traits::eq(at(xpos+I), str.at(I)) for all elements ...
</blockquote>
</li>

<li>
   In lib.string::find.last.not.of paragraph 1 (effects clause for
   find_last_not_of()), second bullet, change

<blockquote>
     at(xpos+I) == str.at(I) for all elements ...
</blockquote>

   to

<blockquote>
     traits::eq(at(xpos+I), str.at(I)) for all elements ...
</blockquote>
</li>

<li>
   In lib.string.ios paragraph 5 (effects clause for getline()),
   second bullet, change

<blockquote>
     c == delim for the next available input character c 
</blockquote>

   to

<blockquote>
     traits::eq(c, delim) for the next available input character c 
</blockquote>
</li>

</ol>

<p>Notes:</p>
<ul>
<li>
  Fixing this issue highlights another sloppyness in
  lib.istream.unformatted paragraph 24: this clause mentions a "character"
  which is then compared to an 'int_type' (see item 5. in the list
  below). It is not clear whether this requires explicit words and
  if so what these words are supposed to be. A similar issue exists,
  BTW, for operator*() of istreambuf_iterator which returns the result
  of sgetc() as a character type (see lib.istreambuf.iterator::op*
  paragraph 1), and for operator++() of istreambuf_iterator which
  passes the result of sbumpc() to a constructor taking a char_type
  (see lib.istreambuf.iterator::operator++ paragraph 3). Similarily, the
  assignment operator ostreambuf_iterator passes a char_type to a function
  taking an int_type (see lib.ostreambuf.iter.ops paragraph 1).
</li>
<li>
  It is inconsistent to use comparisons using the traits functions in
  Chapter 27 while not using them in Chapter 21, especially as some
  of the inconsistent uses actually involve streams (eg. getline() on
  streams). To avoid leaving this issue open still longer due to this
  inconsistency (it is open since 1998), a list of changes to Chapter
  21 is below.
</li>
<li>
  In Chapter 24 there are several places with statements like "the end
  of stream is reached (streambuf_type::sgetc() returns traits::eof())"
  (lib.istreambuf.iterator paragraph 1, lib.ostreambuf.iter.ops
  paragraph 5). It is unclear whether these should be clarified to use
  traits::eq_int_type() for detecting traits::eof().
</li>
</ul>

<hr>
<a name="46"><h3>46.&nbsp;Minor Annex D errors</h3></a><p><b>Section:</b>&nbsp;D.7 <a href="future.html#depr.str.strstreams"> [depr.str.strstreams]</a>&nbsp; <b>Status:</b>&nbsp;<a href="lwg-active.html#TC">TC</a>&nbsp; <b>Submitter:</b>&nbsp;Brendan Kehoe&nbsp; <b>Date:</b>&nbsp; 1 Jun 1998</p>
<p>See lib-6522 and edit-814.</p>
<p><b>Proposed resolution:</b></p>
<p>Change D.7.1 <a href="future.html#depr.strstreambuf"> [depr.strstreambuf]</a> (since streambuf is a typedef of
basic_streambuf&lt;char&gt;) from:</p>

<pre>         virtual streambuf&lt;char&gt;* setbuf(char* s, streamsize n);</pre>

<p>to:</p>

<pre>         virtual streambuf* setbuf(char* s, streamsize n);</pre>

<p>In D.7.4 <a href="future.html#depr.strstream"> [depr.strstream]</a> insert the semicolon now missing after
int_type:</p>

<pre>     namespace std {
       class strstream
         : public basic_iostream&lt;char&gt; {
       public:
         // Types
         typedef char                                char_type;
         typedef typename char_traits&lt;char&gt;::int_type int_type
         typedef typename char_traits&lt;char&gt;::pos_type pos_type;</pre>
<hr>
<a name="47"><h3>47.&nbsp;Imbue() and getloc() Returns clauses swapped</h3></a><p><b>Section:</b>&nbsp;27.4.2.3 <a href="lib-iostreams.html#lib.ios.base.locales"> [lib.ios.base.locales]</a>&nbsp; <b>Status:</b>&nbsp;<a href="lwg-active.html#TC">TC</a>&nbsp; <b>Submitter:</b>&nbsp;Matt Austern&nbsp; <b>Date:</b>&nbsp;21 Jun 1998</p>
<p>Section 27.4.2.3 specifies how imbue() and getloc() work. That
section has two RETURNS clauses, and they make no sense as
stated. They make perfect sense, though, if you swap them. Am I
correct in thinking that paragraphs 2 and 4 just got mixed up by
accident?</p>
<p><b>Proposed resolution:</b></p>
<p>In 27.4.2.3 <a href="lib-iostreams.html#lib.ios.base.locales"> [lib.ios.base.locales]</a> swap paragraphs 2 and 4.</p>
<hr>
<a name="48"><h3>48.&nbsp;Use of non-existent exception constructor</h3></a><p><b>Section:</b>&nbsp;27.4.2.1.1 <a href="lib-iostreams.html#lib.ios::failure"> [lib.ios::failure]</a>&nbsp; <b>Status:</b>&nbsp;<a href="lwg-active.html#TC">TC</a>&nbsp; <b>Submitter:</b>&nbsp;Matt Austern&nbsp; <b>Date:</b>&nbsp;21 Jun 1998</p>
<p>27.4.2.1.1, paragraph 2, says that class failure initializes the
base class, exception, with exception(msg). Class exception (see
18.6.1) has no such constructor.</p>
<p><b>Proposed resolution:</b></p>
<p>Replace 27.4.2.1.1 <a href="lib-iostreams.html#lib.ios::failure"> [lib.ios::failure]</a>, paragraph 2, with</p>

<blockquote>
  <p>EFFECTS: Constructs an object of class <tt>failure</tt>.</p>
</blockquote>
<hr>
<a name="49"><h3>49.&nbsp;Underspecification of ios_base::sync_with_stdio</h3></a><p><b>Section:</b>&nbsp;27.4.2.4 <a href="lib-iostreams.html#lib.ios.members.static"> [lib.ios.members.static]</a>&nbsp; <b>Status:</b>&nbsp;<a href="lwg-active.html#WP">WP</a>&nbsp; <b>Submitter:</b>&nbsp;Matt Austern&nbsp; <b>Date:</b>&nbsp;21 Jun 1998</p>
<p>Two problems</p>

<p>(1) 27.4.2.4 doesn't say what ios_base::sync_with_stdio(f)
returns. Does it return f, or does it return the previous
synchronization state? My guess is the latter, but the standard
doesn't say so.</p>

<p>(2) 27.4.2.4 doesn't say what it means for streams to be
synchronized with stdio.  Again, of course, I can make some
guesses. (And I'm unhappy about the performance implications of those
guesses, but that's another matter.)</p>
<p><b>Proposed resolution:</b></p>
<p>Change the following sentence in 27.4.2.4 <a href="lib-iostreams.html#lib.ios.members.static"> [lib.ios.members.static]</a>
returns clause from:</p>

<blockquote>
  <p><tt>true</tt> if the standard iostream objects (27.3) are
  synchronized and otherwise returns <tt>false</tt>.</p>
</blockquote>

<p>to:</p>

<blockquote>
  <p><tt>true</tt> if the previous state of the standard iostream
  objects (27.3) was synchronized and otherwise returns
  <tt>false</tt>.</p>
</blockquote>

<p>Add the following immediately after 27.4.2.4 <a href="lib-iostreams.html#lib.ios.members.static"> [lib.ios.members.static]</a>,
paragraph 2:</p>

<blockquote>
<p>When a standard iostream object str is <i>synchronized</i> with a
standard stdio stream f, the effect of inserting a character c by</p>
<pre>
  fputc(f, c);
</pre>

<p>is the same as the effect of</p>
<pre>
  str.rdbuf()-&gt;sputc(c);
</pre>

<p>for any sequence of characters; the effect of extracting a
character c by</p>
<pre>
  c = fgetc(f);
</pre>

<p>is the same as the effect of:</p>
<pre>
  c = str.rdbuf()-&gt;sbumpc(c);
</pre>

<p>for any sequences of characters; and the effect of pushing
back a character c by</p>
<pre>
  ungetc(c, f);
</pre>

<p>is the same as the effect of</p>
<pre>
  str.rdbuf()-&gt;sputbackc(c);
</pre>

<p>for any sequence of characters.  [<i>Footnote</i>: This implies
that operations on a standard iostream object can be mixed arbitrarily
with operations on the corresponding stdio stream.  In practical
terms, synchronization usually means that a standard iostream object
and a standard stdio object share a buffer. <i>--End Footnote</i>]</p>
</blockquote>

<p><i>[pre-Copenhagen: PJP and Matt contributed the definition
of "synchronization"]</i></p>

<p><i>[post-Copenhagen: proposed resolution was revised slightly:
text was added in the non-normative footnote to say that operations
on the two streams can be mixed arbitrarily.]</i></p>
<hr>
<a name="50"><h3>50.&nbsp;Copy constructor and assignment operator of ios_base</h3></a><p><b>Section:</b>&nbsp;27.4.2 <a href="lib-iostreams.html#lib.ios.base"> [lib.ios.base]</a>&nbsp; <b>Status:</b>&nbsp;<a href="lwg-active.html#TC">TC</a>&nbsp; <b>Submitter:</b>&nbsp;Matt Austern&nbsp; <b>Date:</b>&nbsp;21 Jun 1998</p>
<p>As written, ios_base has a copy constructor and an assignment
operator. (Nothing in the standard says it doesn't have one, and all
classes have copy constructors and assignment operators unless you
take specific steps to avoid them.) However, nothing in 27.4.2 says
what the copy constructor and assignment operator do. </p>

<p>My guess is that this was an oversight, that ios_base is, like
basic_ios, not supposed to have a copy constructor or an assignment
operator.</p>

<p>
Jerry Schwarz comments: Yes, its an oversight, but in the opposite
sense to what you're suggesting. At one point there was a definite
intention that you could copy ios_base. It's an easy way to save the
entire state of a stream for future use. As you note, to carry out
that intention would have required a explicit description of the
semantics (e.g. what happens to the iarray and parray stuff).
</p>
<p><b>Proposed resolution:</b></p>
<p>In 27.4.2 <a href="lib-iostreams.html#lib.ios.base"> [lib.ios.base]</a>, class ios_base, specify the copy
constructor and operator= members as being private.</p>
<p><b>Rationale:</b></p>
<p>The LWG believes the difficulty of specifying correct semantics
outweighs any benefit of allowing ios_base objects to be copyable.</p>
<hr>
<a name="51"><h3>51.&nbsp;Requirement to not invalidate iterators missing</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#TC">TC</a>&nbsp; <b>Submitter:</b>&nbsp;David Vandevoorde&nbsp; <b>Date:</b>&nbsp;23 Jun 1998</p>
<p>The std::sort algorithm can in general only sort a given sequence
by moving around values. The list&lt;&gt;::sort() member on the other
hand could move around values or just update internal pointers. Either
method can leave iterators into the list&lt;&gt; dereferencable, but
they would point to different things. </p>

<p>Does the FDIS mandate anywhere which method should be used for
list&lt;&gt;::sort()?</p>

<p>Matt Austern comments:</p>

<p>I think you've found an omission in the standard. </p>

<p>The library working group discussed this point, and there was
supposed to be a general requirement saying that list, set, map,
multiset, and multimap may not invalidate iterators, or change the
values that iterators point to, except when an operation does it
explicitly. So, for example, insert() doesn't invalidate any iterators
and erase() and remove() only invalidate iterators pointing to the
elements that are being erased. </p>

<p>I looked for that general requirement in the FDIS, and, while I
found a limited form of it for the sorted associative containers, I
didn't find it for list. It looks like it just got omitted. </p>

<p>The intention, though, is that list&lt;&gt;::sort does not
invalidate any iterators and does not change the values that any
iterator points to. There would be no reason to have the member
function otherwise.</p>
<p><b>Proposed resolution:</b></p>
<p>Add a new paragraph at the end of 23.1:</p>

<blockquote>
  <p>Unless otherwise specified (either explicitly or by defining a function in terms of
  other functions), invoking a container member function or passing a container as an
  argument to a library function shall not invalidate iterators to, or change the values of,
  objects within that container. </p>
</blockquote>
<p><b>Rationale:</b></p>
<p>This was US issue CD2-23-011; it was accepted in London but the
change was not made due to an editing oversight. The wording in the
proposed resolution below is somewhat updated from CD2-23-011,
particularly the addition of the phrase "or change the values
of"</p>
<hr>
<a name="52"><h3>52.&nbsp;Small I/O problems</h3></a><p><b>Section:</b>&nbsp;27.4.3.2 <a href="lib-iostreams.html#lib.fpos.operations"> [lib.fpos.operations]</a>&nbsp; <b>Status:</b>&nbsp;<a href="lwg-active.html#TC">TC</a>&nbsp; <b>Submitter:</b>&nbsp;Matt Austern&nbsp; <b>Date:</b>&nbsp;23 Jun 1998</p>
<p>First, 27.4.4.1 <a href="lib-iostreams.html#lib.basic.ios.cons"> [lib.basic.ios.cons]</a>, table 89. This is pretty obvious:
it should be titled "basic_ios&lt;&gt;() effects", not
"ios_base() effects". </p>

<p>[The second item is a duplicate; see issue <a href="lwg-closed.html#6">6</a> for
resolution.]</p>

<p>Second, 27.4.3.2 <a href="lib-iostreams.html#lib.fpos.operations"> [lib.fpos.operations]</a> table 88 . There are a couple
different things wrong with it, some of which I've already discussed
with Jerry, but the most obvious mechanical sort of error is that it
uses expressions like P(i) and p(i), without ever defining what sort
of thing "i" is.
</p>

<p>(The other problem is that it requires support for streampos
arithmetic. This is impossible on some systems, i.e. ones where file
position is a complicated structure rather than just a number. Jerry
tells me that the intention was to require syntactic support for
streampos arithmetic, but that it wasn't actually supposed to do
anything meaningful except on platforms, like Unix, where genuine
arithmetic is possible.) </p>
<p><b>Proposed resolution:</b></p>
<p>Change 27.4.4.1 <a href="lib-iostreams.html#lib.basic.ios.cons"> [lib.basic.ios.cons]</a> table 89 title from
"ios_base() effects" to "basic_ios&lt;&gt;()
effects". </p>
<hr>
<a name="53"><h3>53.&nbsp;Basic_ios destructor unspecified</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#TC">TC</a>&nbsp; <b>Submitter:</b>&nbsp;Matt Austern&nbsp; <b>Date:</b>&nbsp;23 Jun 1998</p>
<p>There's nothing in 27.4.4 saying what basic_ios's destructor does.
The important question is whether basic_ios::~basic_ios() destroys
rdbuf().</p>
<p><b>Proposed resolution:</b></p>
<p>Add after 27.4.4.1 <a href="lib-iostreams.html#lib.basic.ios.cons"> [lib.basic.ios.cons]</a> paragraph 2:</p>

<blockquote>
  <p><tt>virtual ~basic_ios();</tt></p>
  <p><b>Notes</b>: The destructor does not destroy <tt>rdbuf()</tt>.</p>
</blockquote>
<p><b>Rationale:</b></p> 
<p>The LWG reviewed the additional question of whether or not
<tt>rdbuf(0)</tt> may set <tt>badbit</tt>.  The answer is
clearly yes; it may be set via <tt>clear()</tt>.  See 27.4.4.2 <a href="lib-iostreams.html#lib.basic.ios.members"> [lib.basic.ios.members]</a>, paragraph 6.  This issue was reviewed at length
by the LWG, which removed from the original proposed resolution a
footnote which incorrectly said "<tt>rdbuf(0)</tt> does not set
<tt>badbit</tt>".</p>
<hr>
<a name="54"><h3>54.&nbsp;Basic_streambuf's destructor</h3></a><p><b>Section:</b>&nbsp;27.5.2.1 <a href="lib-iostreams.html#lib.streambuf.cons"> [lib.streambuf.cons]</a>&nbsp; <b>Status:</b>&nbsp;<a href="lwg-active.html#TC">TC</a>&nbsp; <b>Submitter:</b>&nbsp;Matt Austern&nbsp; <b>Date:</b>&nbsp;25 Jun 1998</p>
<p>The class synopsis for basic_streambuf shows a (virtual)
destructor, but the standard doesn't say what that destructor does. My
assumption is that it does nothing, but the standard should say so
explicitly. </p>
<p><b>Proposed resolution:</b></p>
<p>Add after 27.5.2.1 <a href="lib-iostreams.html#lib.streambuf.cons"> [lib.streambuf.cons]</a> paragraph 2:</p>

<blockquote>
  <p><tt>virtual&nbsp; ~basic_streambuf();</tt></p>
  <p><b>Effects</b>: None.</p>
</blockquote>
<hr>
<a name="55"><h3>55.&nbsp;Invalid stream position is undefined</h3></a><p><b>Section:</b>&nbsp;27 <a href="lib-iostreams.html#lib.input.output"> [lib.input.output]</a>&nbsp; <b>Status:</b>&nbsp;<a href="lwg-active.html#TC">TC</a>&nbsp; <b>Submitter:</b>&nbsp;Matt Austern&nbsp; <b>Date:</b>&nbsp;26 Jun 1998</p>
<p>Several member functions in clause 27 are defined in certain
circumstances to return an "invalid stream position", a term
that is defined nowhere in the standard. Two places (27.5.2.4.2,
paragraph 4, and 27.8.1.4, paragraph 15) contain a cross-reference to
a definition in _lib.iostreams.definitions_, a nonexistent
section. </p>

<p>I suspect that the invalid stream position is just supposed to be
pos_type(-1).  Probably best to say explicitly in (for example)
27.5.2.4.2 that the return value is pos_type(-1), rather than to use
the term "invalid stream position", define that term
somewhere, and then put in a cross-reference. </p>

<p>The phrase "invalid stream position" appears ten times in
the C++ Standard.  In seven places it refers to a return value, and it
should be changed. In three places it refers to an argument, and it
should not be changed. Here are the three places where "invalid
stream position" should not be changed:</p>

<blockquote>
  <p>27.7.1.3 <a href="lib-iostreams.html#lib.stringbuf.virtuals"> [lib.stringbuf.virtuals]</a>, paragraph 14<br>
  27.8.1.4 <a href="lib-iostreams.html#lib.filebuf.virtuals"> [lib.filebuf.virtuals]</a>, paragraph 14<br>
  D.7.1.3 <a href="future.html#depr.strstreambuf.virtuals"> [depr.strstreambuf.virtuals]</a>, paragraph 17
  </p>
</blockquote>
<p><b>Proposed resolution:</b></p>
<p>In 27.5.2.4.2 <a href="lib-iostreams.html#lib.streambuf.virt.buffer"> [lib.streambuf.virt.buffer]</a>, paragraph 4, change "Returns an
object of class pos_type that stores an invalid stream position
(_lib.iostreams.definitions_)" to "Returns
<tt>pos_type(off_type(-1))</tt>".
</p>

<p>In 27.5.2.4.2 <a href="lib-iostreams.html#lib.streambuf.virt.buffer"> [lib.streambuf.virt.buffer]</a>, paragraph 6, change "Returns
an object of class pos_type that stores an invalid stream
position" to "Returns <tt>pos_type(off_type(-1))</tt>".</p>

<p>In 27.7.1.3 <a href="lib-iostreams.html#lib.stringbuf.virtuals"> [lib.stringbuf.virtuals]</a>, paragraph 13, change "the object
stores an invalid stream position" to "the return value is
<tt>pos_type(off_type(-1))</tt>". </p>

<p>In 27.8.1.4 <a href="lib-iostreams.html#lib.filebuf.virtuals"> [lib.filebuf.virtuals]</a>, paragraph 13, change "returns an
invalid stream position (27.4.3)" to "returns
<tt>pos_type(off_type(-1))</tt>" </p>

<p>In 27.8.1.4 <a href="lib-iostreams.html#lib.filebuf.virtuals"> [lib.filebuf.virtuals]</a>, paragraph 15, change "Otherwise
returns an invalid stream position (_lib.iostreams.definitions_)"
to "Otherwise returns <tt>pos_type(off_type(-1))</tt>"
</p>

<p>In D.7.1.3 <a href="future.html#depr.strstreambuf.virtuals"> [depr.strstreambuf.virtuals]</a>, paragraph 15, change "the object
stores an invalid stream position" to "the return value is
<tt>pos_type(off_type(-1))</tt>" </p>

<p>In D.7.1.3 <a href="future.html#depr.strstreambuf.virtuals"> [depr.strstreambuf.virtuals]</a>, paragraph 18, change "the object
stores an invalid stream position" to "the return value is
<tt>pos_type(off_type(-1))</tt>"</p>
<hr>
<a name="56"><h3>56.&nbsp;Showmanyc's return type</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#TC">TC</a>&nbsp; <b>Submitter:</b>&nbsp;Matt Austern&nbsp; <b>Date:</b>&nbsp;29 Jun 1998</p>
<p>The class summary for basic_streambuf&lt;&gt;, in 27.5.2, says that
showmanyc has return type int. However, 27.5.2.4.3 says that its
return type is streamsize. </p>
<p><b>Proposed resolution:</b></p>
<p>Change <tt>showmanyc</tt>'s return type in the
27.5.2 <a href="lib-iostreams.html#lib.streambuf"> [lib.streambuf]</a> class summary to <tt>streamsize</tt>.</p>
<hr>
<a name="57"><h3>57.&nbsp;Mistake in char_traits</h3></a><p><b>Section:</b>&nbsp;21.1.3.2 <a href="lib-strings.html#lib.char.traits.specializations.wchar.t"> [lib.char.traits.specializations.wchar.t]</a>&nbsp; <b>Status:</b>&nbsp;<a href="lwg-active.html#TC">TC</a>&nbsp; <b>Submitter:</b>&nbsp;Matt Austern&nbsp; <b>Date:</b>&nbsp;1 Jul 1998</p>
<p>21.1.3.2, paragraph 3, says "The types streampos and
wstreampos may be different if the implementation supports no shift
encoding in narrow-oriented iostreams but supports one or more shift
encodings in wide-oriented streams". </p>

<p>That's wrong: the two are the same type. The &lt;iosfwd&gt; summary
in 27.2 says that streampos and wstreampos are, respectively, synonyms
for fpos&lt;char_traits&lt;char&gt;::state_type&gt; and
fpos&lt;char_traits&lt;wchar_t&gt;::state_type&gt;, and, flipping back
to clause 21, we see in 21.1.3.1 and 21.1.3.2 that
char_traits&lt;char&gt;::state_type and
char_traits&lt;wchar_t&gt;::state_type must both be mbstate_t. </p>
<p><b>Proposed resolution:</b></p>
<p>Remove the sentence in 21.1.3.2 <a href="lib-strings.html#lib.char.traits.specializations.wchar.t"> [lib.char.traits.specializations.wchar.t]</a> paragraph 3 which
begins "The types streampos and wstreampos may be
different..." . </p>
<hr>
<a name="59"><h3>59.&nbsp;Ambiguity in specification of gbump</h3></a><p><b>Section:</b>&nbsp;27.5.2.3.1 <a href="lib-iostreams.html#lib.streambuf.get.area"> [lib.streambuf.get.area]</a>&nbsp; <b>Status:</b>&nbsp;<a href="lwg-active.html#TC">TC</a>&nbsp; <b>Submitter:</b>&nbsp;Matt Austern&nbsp; <b>Date:</b>&nbsp;28 Jul 1998</p>
<p>27.5.2.3.1 says that basic_streambuf::gbump() "Advances the
next pointer for the input sequence by n." </p>

<p>The straightforward interpretation is that it is just gptr() +=
n. An alternative interpretation, though, is that it behaves as if it
calls sbumpc n times. (The issue, of course, is whether it might ever
call underflow.) There is a similar ambiguity in the case of
pbump. </p>

<p>(The "classic" AT&amp;T implementation used the
former interpretation.)</p>
<p><b>Proposed resolution:</b></p>
<p>Change 27.5.2.3.1 <a href="lib-iostreams.html#lib.streambuf.get.area"> [lib.streambuf.get.area]</a> paragraph 4 gbump effects from:</p>

<blockquote>
  <p>Effects: Advances the next pointer for the input sequence by n.</p>
</blockquote>

<p>to:</p>

<blockquote>
  <p>Effects: Adds <tt>n</tt> to the next pointer for the input sequence.</p>
</blockquote>

<p>Make the same change to 27.5.2.3.2 <a href="lib-iostreams.html#lib.streambuf.put.area"> [lib.streambuf.put.area]</a> paragraph 4 pbump
effects.</p>
<hr>
<a name="60"><h3>60.&nbsp;What is a formatted input function?</h3></a><p><b>Section:</b>&nbsp;27.6.1.2.1 <a href="lib-iostreams.html#lib.istream.formatted.reqmts"> [lib.istream.formatted.reqmts]</a>&nbsp; <b>Status:</b>&nbsp;<a href="lwg-active.html#TC">TC</a>&nbsp; <b>Submitter:</b>&nbsp;Matt Austern&nbsp; <b>Date:</b>&nbsp;3 Aug 1998</p>
<p>Paragraph 1 of 27.6.1.2.1 contains general requirements for all
formatted input functions. Some of the functions defined in section
27.6.1.2 explicitly say that those requirements apply ("Behaves
like a formatted input member (as described in 27.6.1.2.1)"), but
others don't. The question: is 27.6.1.2.1 supposed to apply to
everything in 27.6.1.2, or only to those member functions that
explicitly say "behaves like a formatted input member"? Or
to put it differently: are we to assume that everything that appears
in a section called "Formatted input functions" really is a
formatted input function? I assume that 27.6.1.2.1 is intended to
apply to the arithmetic extractors (27.6.1.2.2), but I assume that it
is not intended to apply to extractors like </p>

<pre>    basic_istream&amp; operator&gt;&gt;(basic_istream&amp; (*pf)(basic_istream&amp;));</pre>

<p>and </p>

<pre>    basic_istream&amp; operator&gt;&gt;(basic_streammbuf*);</pre>

<p>There is a similar ambiguity for unformatted input, formatted output, and unformatted
output. </p>

<p>Comments from Judy Ward: It seems like the problem is that the
basic_istream and basic_ostream operator &lt;&lt;()'s that are used
for the manipulators and streambuf* are in the wrong section and
should have their own separate section or be modified to make it clear
that the "Common requirements" listed in section 27.6.1.2.1
(for basic_istream) and section 27.6.2.5.1 (for basic_ostream) do not
apply to them. </p>

<p>Additional comments from Dietmar K&uuml;hl: It appears to be somewhat
nonsensical to consider the functions defined in 27.6.1.2.3 <a href="lib-iostreams.html#lib.istream::extractors"> [lib.istream::extractors]</a> 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>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>
In 27.6.1.2.2 [lib.istream.formatted.arithmetic], paragraph 1.
Change the beginning of the second sentence from "The conversion
occurs" to "These extractors behave as formatted input functions (as
described in 27.6.1.2.1).  After a sentry object is constructed,
the conversion occurs"
</p>

<p>
In 27.6.1.2.3, [lib.istream::extractors], before paragraph 1.
Add an effects clause.  "Effects: None.  This extractor does
not behave as a formatted input function (as described in
27.6.1.2.1).
</p>

<p>
In 27.6.1.2.3, [lib.istream::extractors], paragraph 2.  Change the
effects clause to "Effects: Calls pf(*this).  This extractor does not
behave as a formatted input function (as described in 27.6.1.2.1).
</p>

<p>
In 27.6.1.2.3, [lib.istream::extractors], paragraph 4.  Change the
effects clause to "Effects: Calls pf(*this).  This extractor does not
behave as a formatted input function (as described in 27.6.1.2.1).
</p>

<p>
In 27.6.1.2.3, [lib.istream::extractors], paragraph 12.  Change the
first two sentences from "If sb is null, calls setstate(failbit),
which may throw ios_base::failure (27.4.4.3).  Extracts characters
from *this..." to "Behaves as a formatted input function (as described
in 27.6.1.2.1).  If sb is null, calls setstate(failbit), which may
throw ios_base::failure (27.4.4.3).  After a sentry object is
constructed, extracts characters from *this...".
</p>

<p>
In 27.6.1.3, [lib.istream.unformatted], before paragraph 2.  Add an
effects clause.  "Effects: none. This member function does not behave
as an unformatted input function (as described in 27.6.1.3, paragraph 1)."
</p>

<p>
In 27.6.1.3, [lib.istream.unformatted], paragraph 3.  Change the
beginning of the first sentence of the effects clause from "Extracts a
character" to "Behaves as an unformatted input function (as described
in 27.6.1.3, paragraph 1).  After constructing a sentry object, extracts a
character"
</p>

<p>
In 27.6.1.3, [lib.istream.unformatted], paragraph 5.  Change the
beginning of the first sentence of the effects clause from "Extracts a
character" to "Behaves as an unformatted input function (as described
in 27.6.1.3, paragraph 1).  After constructing a sentry object, extracts a
character"
</p>

<p>
In 27.6.1.3, [lib.istream.unformatted], paragraph 5.  Change the
beginning of the first sentence of the effects clause from "Extracts
characters" to "Behaves as an unformatted input function (as described
in 27.6.1.3, paragraph 1).  After constructing a sentry object, extracts
characters"
</p>

<p>
[No change needed in paragraph 10, because it refers to paragraph 7.]
</p>

<p>
In 27.6.1.3, [lib.istream.unformatted], paragraph 12.  Change the
beginning of the first sentence of the effects clause from "Extracts
characters" to "Behaves as an unformatted input function (as described
in 27.6.1.3, paragraph 1).  After constructing a sentry object, extracts
characters"
</p>

<p>
[No change needed in paragraph 15.]
</p>

<p>
In 27.6.1.3, [lib.istream.unformatted], paragraph 17.  Change the
beginning of the first sentence of the effects clause from "Extracts
characters" to "Behaves as an unformatted input function (as described
in 27.6.1.3, paragraph 1).  After constructing a sentry object, extracts
characters"
</p>

<p>
[No change needed in paragraph 23.]
</p>

<p>
In 27.6.1.3, [lib.istream.unformatted], paragraph 24.  Change the
beginning of the first sentence of the effects clause from "Extracts
characters" to "Behaves as an unformatted input function (as described
in 27.6.1.3, paragraph 1).  After constructing a sentry object, extracts
characters"
</p>

<p>
In 27.6.1.3, [lib.istream.unformatted], before paragraph 27.  Add an
Effects clause: "Effects: Behaves as an unformatted input function (as
described in 27.6.1.3, paragraph 1).  After constructing a sentry
object, reads but does not extract the current input character."
</p>

<p>
In 27.6.1.3, [lib.istream.unformatted], paragraph 28.  Change the
first sentence of the Effects clause from "If !good() calls" to
Behaves as an unformatted input function (as described in 27.6.1.3,
paragraph 1).  After constructing a sentry object, if !good() calls"
</p>

<p>
In 27.6.1.3, [lib.istream.unformatted], paragraph 30.  Change the
first sentence of the Effects clause from "If !good() calls" to
"Behaves as an unformatted input function (as described in 27.6.1.3,
paragraph 1).  After constructing a sentry object, if !good() calls"
</p>

<p>
In 27.6.1.3, [lib.istream.unformatted], paragraph 32.  Change the
first sentence of the Effects clause from "If !good() calls..." to
"Behaves as an unformatted input function (as described in 27.6.1.3,
paragraph 1).  After constructing a sentry object, if !good()
calls..."  Add a new sentence to the end of the Effects clause:
"[Note: this function extracts no characters, so the value returned
by the next call to gcount() is 0.]"
</p>

<p>
In 27.6.1.3, [lib.istream.unformatted], paragraph 34.  Change the
first sentence of the Effects clause from "If !good() calls" to
"Behaves as an unformatted input function (as described in 27.6.1.3,
paragraph 1).  After constructing a sentry object, if !good() calls".
Add a new sentence to the end of the Effects clause: "[Note: this
function extracts no characters, so the value returned by the next
call to gcount() is 0.]"
</p>

<p>
In 27.6.1.3, [lib.istream.unformatted], paragraph 36.  Change the
first sentence of the Effects clause from "If !rdbuf() is" to "Behaves
as an unformatted input function (as described in 27.6.1.3, paragraph
1), except that it does not count the number of characters extracted
and does not affect the value returned by subsequent calls to
gcount().  After constructing a sentry object, if rdbuf() is"
</p>

<p>
In 27.6.1.3, [lib.istream.unformatted], before paragraph 37.  Add an
Effects clause: "Effects: Behaves as an unformatted input function (as
described in 27.6.1.3, paragraph 1), except that it does not count the
number of characters extracted and does not affect the value returned
by subsequent calls to gcount()."  Change the first sentence of
paragraph 37 from "if fail()" to "after constructing a sentry object,
if fail()".
</p>

<p>
In 27.6.1.3, [lib.istream.unformatted], paragraph 38.  Change the
first sentence of the Effects clause from "If fail()" to "Behaves
as an unformatted input function (as described in 27.6.1.3, paragraph
1), except that it does not count the number of characters extracted
and does not affect the value returned by subsequent calls to
gcount().  After constructing a sentry object, if fail()
</p>

<p>
In 27.6.1.3, [lib.istream.unformatted], paragraph 40.  Change the
first sentence of the Effects clause from "If fail()" to "Behaves
as an unformatted input function (as described in 27.6.1.3, paragraph
1), except that it does not count the number of characters extracted
and does not affect the value returned by subsequent calls to
gcount().  After constructing a sentry object, if fail()
</p>

<p>
In 27.6.2.5.2 [lib.ostream.inserters.arithmetic], paragraph 1.  Change
the beginning of the third sentence from "The formatting conversion"
to "These extractors behave as formatted output functions (as
described in 27.6.2.5.1).  After the sentry object is constructed, the
conversion occurs".
</p>

<p>
In 27.6.2.5.3 [lib.ostream.inserters], before paragraph 1.  Add an
effects clause: "Effects: None. Does not behave as a formatted output
function (as described in 27.6.2.5.1).".
</p>

<p>
In 27.6.2.5.3 [lib.ostream.inserters], paragraph 2.  Change the
effects clause to "Effects: calls pf(*this).  This extractor does not
behave as a formatted output function (as described in 27.6.2.5.1).".
</p>

<p>
In 27.6.2.5.3 [lib.ostream.inserters], paragraph 4.  Change the
effects clause to "Effects: calls pf(*this).  This extractor does not
behave as a formatted output function (as described in 27.6.2.5.1).".
</p>

<p>
In 27.6.2.5.3 [lib.ostream.inserters], paragraph 6.  Change the first
sentence from "If sb" to "Behaves as a formatted output function (as
described in 27.6.2.5.1).  After the sentry object is constructed, if
sb".
</p>

<p>
In 27.6.2.6 [lib.ostream.unformatted], paragraph 2.  Change the first
sentence from "Inserts the character" to "Behaves as an unformatted
output function (as described in 27.6.2.6, paragraph 1).  After
constructing a sentry object, inserts the character".
</p>

<p>
In 27.6.2.6 [lib.ostream.unformatted], paragraph 5.  Change the first
sentence from "Obtains characters" to "Behaves as an unformatted
output function (as described in 27.6.2.6, paragraph 1).  After
constructing a sentry object, obtains characters".
</p>

<p>
In 27.6.2.6 [lib.ostream.unformatted], paragraph 7.  Add a new
sentence at the end of the paragraph: "Does not behave as an
unformatted output function (as described in 27.6.2.6, paragraph 1)."
</p>
<p><b>Rationale:</b></p>
<p>See J16/99-0043==WG21/N1219, Proposed Resolution to Library Issue 60,
by Judy Ward and Matt Austern.  This proposed resolution is section
VI of that paper.</p>
<hr>
<a name="61"><h3>61.&nbsp;Ambiguity in iostreams exception policy</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#TC">TC</a>&nbsp; <b>Submitter:</b>&nbsp;Matt Austern&nbsp; <b>Date:</b>&nbsp;6 Aug 1998</p>
<p>The introduction to the section on unformatted input (27.6.1.3)
says that every unformatted input function catches all exceptions that
were thrown during input, sets badbit, and then conditionally rethrows
the exception. That seems clear enough. Several of the specific
functions, however, such as get() and read(), are documented in some
circumstances as setting eofbit and/or failbit. (The standard notes,
correctly, that setting eofbit or failbit can sometimes result in an
exception being thrown.) The question: if one of these functions
throws an exception triggered by setting failbit, is this an exception
"thrown during input" and hence covered by 27.6.1.3, or does
27.6.1.3 only refer to a limited class of exceptions? Just to make
this concrete, suppose you have the following snippet. </p>

<pre>  
  char buffer[N];
  istream is;
  ...
  is.exceptions(istream::failbit); // Throw on failbit but not on badbit.
  is.read(buffer, N);</pre>

<p>Now suppose we reach EOF before we've read N characters. What
iostate bits can we expect to be set, and what exception (if any) will
be thrown? </p>
<p><b>Proposed resolution:</b></p>
<p>
In 27.6.1.3, paragraph 1, after the sentence that begins
"If an exception is thrown...", add the following
parenthetical comment: "(Exceptions thrown from 
<tt>basic_ios&lt;&gt;::clear()</tt> are not caught or rethrown.)"
</p>
<p><b>Rationale:</b></p>
<p>The LWG looked to two alternative wordings, and choose the proposed
resolution as better standardese.</p>
<hr>
<a name="62"><h3>62.&nbsp;<tt>Sync</tt>'s return value</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#TC">TC</a>&nbsp; <b>Submitter:</b>&nbsp;Matt Austern&nbsp; <b>Date:</b>&nbsp;6 Aug 1998</p>
<p>The Effects clause for sync() (27.6.1.3, paragraph 36) says that it
"calls rdbuf()-&gt;pubsync() and, if that function returns -1
... returns traits::eof()." </p>

<p>That looks suspicious, because traits::eof() is of type
traits::int_type while the return type of sync() is int. </p>
<p><b>Proposed resolution:</b></p>
<p>In 27.6.1.3 <a href="lib-iostreams.html#lib.istream.unformatted"> [lib.istream.unformatted]</a>, paragraph 36, change "returns
<tt>traits::eof()</tt>" to "returns <tt>-1</tt>".
</p>
<hr>
<a name="63"><h3>63.&nbsp;Exception-handling policy for unformatted output</h3></a><p><b>Section:</b>&nbsp;27.6.2.6 <a href="lib-iostreams.html#lib.ostream.unformatted"> [lib.ostream.unformatted]</a>&nbsp; <b>Status:</b>&nbsp;<a href="lwg-active.html#TC">TC</a>&nbsp; <b>Submitter:</b>&nbsp;Matt Austern&nbsp; <b>Date:</b>&nbsp;11 Aug 1998</p>
<p>Clause 27 details an exception-handling policy for formatted input,
unformatted input, and formatted output. It says nothing for
unformatted output (27.6.2.6). 27.6.2.6 should either include the same
kind of exception-handling policy as in the other three places, or
else it should have a footnote saying that the omission is
deliberate. </p>
<p><b>Proposed resolution:</b></p>
<p>
In 27.6.2.6, paragraph 1, replace the last sentence ("In any
case, the unformatted output function ends by destroying the sentry
object, then returning the value specified for the formatted output
function.") with the following text:
</p>
<blockquote>
If an exception is thrown during output, then <tt>ios::badbit</tt> is
turned on [Footnote: without causing an <tt>ios::failure</tt> to be
thrown.] in <tt>*this</tt>'s error state. If <tt>(exceptions() &amp;
badbit) != 0</tt> then the exception is rethrown.  In any case, the
unformatted output function ends by destroying the sentry object,
then, if no exception was thrown, returning the value specified for
the formatted output function.
</blockquote>
<p><b>Rationale:</b></p>
<p>
This exception-handling policy is consistent with that of formatted
input, unformatted input, and formatted output.
</p>
<hr>
<a name="64"><h3>64.&nbsp;Exception handling in <tt>basic_istream::operator&gt;&gt;(basic_streambuf*)</tt>
</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#TC">TC</a>&nbsp; <b>Submitter:</b>&nbsp;Matt Austern&nbsp; <b>Date:</b>&nbsp;11 Aug 1998 </p>
<p>27.6.1.2.3, paragraph 13, is ambiguous. It can be interpreted two
different ways, depending on whether the second sentence is read as an
elaboration of the first. </p>
<p><b>Proposed resolution:</b></p>
<p>Replace 27.6.1.2.3 <a href="lib-iostreams.html#lib.istream::extractors"> [lib.istream::extractors]</a>, paragraph 13, which begins
"If the function inserts no characters ..." with:</p>

<blockquote>
  <p>If the function inserts no characters, it calls
  <tt>setstate(failbit)</tt>, which may throw
  <tt>ios_base::failure</tt> (27.4.4.3). If it inserted no characters
  because it caught an exception thrown while extracting characters
  from <tt>sb</tt> and <tt>failbit</tt> is on in <tt>exceptions()</tt>
  (27.4.4.3), then the caught exception is rethrown. </p>
</blockquote>
<hr>
<a name="66"><h3>66.&nbsp;Strstreambuf::setbuf</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#TC">TC</a>&nbsp; <b>Submitter:</b>&nbsp;Matt Austern&nbsp; <b>Date:</b>&nbsp;18 Aug 1998</p>
<p>D.7.1.3, paragraph 19, says that strstreambuf::setbuf
"Performs an operation that is defined separately for each class
derived from strstreambuf". This is obviously an incorrect
cut-and-paste from basic_streambuf. There are no classes derived from
strstreambuf. </p>
<p><b>Proposed resolution:</b></p>
<p>D.7.1.3 <a href="future.html#depr.strstreambuf.virtuals"> [depr.strstreambuf.virtuals]</a>, paragraph 19, replace the setbuf effects
clause which currently says "Performs an operation that is
defined separately for each class derived from strstreambuf"
with:</p>

<blockquote>
  <p><b>Effects</b>: implementation defined, except that
  <tt>setbuf(0,0)</tt> has no effect.</p>
</blockquote>
<hr>
<a name="68"><h3>68.&nbsp;Extractors for char* should store null at end</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#TC">TC</a>&nbsp; <b>Submitter:</b>&nbsp;Angelika Langer&nbsp; <b>Date:</b>&nbsp;14 Jul 1998</p>
<p>Extractors for char* (27.6.1.2.3) do not store a null character
after the extracted character sequence whereas the unformatted
functions like get() do. Why is this?</p>

<p>Comment from Jerry Schwarz: There is apparently an editing
glitch. You'll notice that the last item of the list of what stops
extraction doesn't make any sense. It was supposed to be the line that
said a null is stored.</p>
<p><b>Proposed resolution:</b></p>
<p>27.6.1.2.3 <a href="lib-iostreams.html#lib.istream::extractors"> [lib.istream::extractors]</a>, paragraph 7, change the last list
item from:</p>

<blockquote>
  A null byte (<tt>charT()</tt>) in the next position, which may be
  the first position if no characters were extracted.
</blockquote>

<p>to become a new paragraph which reads:</p>

<blockquote>
  Operator&gt;&gt; then stores a null byte (<tt>charT()</tt>) in the
  next position, which may be the first position if no characters were
  extracted.
</blockquote>
<hr>
<a name="69"><h3>69.&nbsp;Must elements of a vector be contiguous?</h3></a><p><b>Section:</b>&nbsp;23.2.4 <a href="lib-containers.html#lib.vector"> [lib.vector]</a>&nbsp; <b>Status:</b>&nbsp;<a href="lwg-active.html#TC">TC</a>&nbsp; <b>Submitter:</b>&nbsp;Andrew Koenig&nbsp; <b>Date:</b>&nbsp;29 Jul 1998</p>
<p>The issue is this: Must the elements of a vector be in contiguous memory?</p>

<p>(Please note that this is entirely separate from the question of
whether a vector iterator is required to be a pointer; the answer to
that question is clearly "no," as it would rule out
debugging implementations)</p>
<p><b>Proposed resolution:</b></p>
<p>Add the following text to the end of 23.2.4 <a href="lib-containers.html#lib.vector"> [lib.vector]</a>,
paragraph 1. </p>

<blockquote>
  <p>The elements of a vector are stored contiguously, meaning that if
  v is a <tt>vector&lt;T, Allocator&gt;</tt> where T is some type
  other than <tt>bool</tt>, then it obeys the identity <tt>&amp;v[n]
  == &amp;v[0] + n</tt> for all <tt>0 &lt;= n &lt; v.size()</tt>.</p>
</blockquote>
<p><b>Rationale:</b></p>
<p>The LWG feels that as a practical matter the answer is clearly
"yes".  There was considerable discussion as to the best way
to express the concept of "contiguous", which is not
directly defined in the standard.  Discussion included:</p>

<ul>
  <li>An operational definition similar to the above proposed resolution is 
    already used for valarray (26.3.2.3 <a href="lib-numerics.html#lib.valarray.access"> [lib.valarray.access]</a>).</li>
  <li>There is no need to explicitly consider a user-defined operator&amp; 
    because elements must be copyconstructible (23.1 <a href="lib-containers.html#lib.container.requirements"> [lib.container.requirements]</a> para 3) 
    and copyconstructible (20.1.3 <a href="lib-utilities.html#lib.copyconstructible"> [lib.copyconstructible]</a>) specifies
    requirements for operator&amp;.</li>
  <li>There is no issue of one-past-the-end because of language rules.</li>
</ul>
<hr>
<a name="70"><h3>70.&nbsp;Uncaught_exception() missing throw() specification</h3></a><p><b>Section:</b>&nbsp;18.6 <a href="lib-support.html#lib.support.exception"> [lib.support.exception]</a>, 18.6.4 <a href="lib-support.html#lib.uncaught"> [lib.uncaught]</a>&nbsp; <b>Status:</b>&nbsp;<a href="lwg-active.html#TC">TC</a>&nbsp; <b>Submitter:</b>&nbsp;Steve Clamage&nbsp; <b>Date:</b>&nbsp;Unknown</p>
<p>In article 3E04@pratique.fr, Valentin Bonnard writes: </p>

<p>uncaught_exception() doesn't have a throw specification.</p>

<p>It is intentional ? Does it means that one should be prepared to
handle exceptions thrown from uncaught_exception() ?</p>

<p>uncaught_exception() is called in exception handling contexts where
exception safety is very important.</p>
<p><b>Proposed resolution:</b></p>
<p>In 15.5.3 <a href="except.html#except.uncaught"> [except.uncaught]</a>, paragraph 1, 18.6 <a href="lib-support.html#lib.support.exception"> [lib.support.exception]</a>, and 18.6.4 <a href="lib-support.html#lib.uncaught"> [lib.uncaught]</a>, add "throw()" to uncaught_exception().</p>
<hr>
<a name="71"><h3>71.&nbsp;Do_get_monthname synopsis missing argument</h3></a><p><b>Section:</b>&nbsp;22.2.5.1 <a href="lib-locales.html#lib.locale.time.get"> [lib.locale.time.get]</a>&nbsp; <b>Status:</b>&nbsp;<a href="lwg-active.html#TC">TC</a>&nbsp; <b>Submitter:</b>&nbsp;Nathan Myers&nbsp; <b>Date:</b>&nbsp;13 Aug 1998</p>
<p>The locale facet member <tt>time_get&lt;&gt;::do_get_monthname</tt>
is described in 22.2.5.1.2 <a href="lib-locales.html#lib.locale.time.get.virtuals"> [lib.locale.time.get.virtuals]</a> with five arguments,
consistent with do_get_weekday and with its specified use by member
get_monthname. However, in the synopsis, it is specified instead with
four arguments. The missing argument is the "end" iterator
value.</p>
<p><b>Proposed resolution:</b></p>
<p>In 22.2.5.1 <a href="lib-locales.html#lib.locale.time.get"> [lib.locale.time.get]</a>, add an "end" argument to
the declaration of member do_monthname as follows:</p>

<pre>  virtual iter_type do_get_monthname(iter_type s, iter_type end, ios_base&amp;,
                                     ios_base::iostate&amp; err, tm* t) const;</pre>
<hr>
<a name="74"><h3>74.&nbsp;Garbled text for <tt>codecvt::do_max_length</tt>
</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#TC">TC</a>&nbsp; <b>Submitter:</b>&nbsp;Matt Austern&nbsp; <b>Date:</b>&nbsp;8 Sep 1998</p>
<p>The text of <tt>codecvt::do_max_length</tt>'s "Returns"
clause (22.2.1.5.2, paragraph 11) is garbled. It has unbalanced
parentheses and a spurious <b>n</b>.</p>
<p><b>Proposed resolution:</b></p>
<p>Replace 22.2.1.5.2 <a href="lib-locales.html#lib.locale.codecvt.virtuals"> [lib.locale.codecvt.virtuals]</a> paragraph 11 with the
following:</p>

<blockquote>
  <b>Returns</b>: The maximum value that
  <tt>do_length(state, from, from_end, 1)</tt> can return for any
  valid range <tt>[from, from_end)</tt> and <tt>stateT</tt> value
  <tt>state</tt>. The specialization <tt>codecvt&lt;char, char,
  mbstate_t&gt;::do_max_length()</tt> returns 1.
</blockquote>
<hr>
<a name="75"><h3>75.&nbsp;Contradiction in <tt>codecvt::length</tt>'s argument types</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#TC">TC</a>&nbsp; <b>Submitter:</b>&nbsp; Matt
Austern&nbsp; <b>Date:</b>&nbsp; 18 Sep 1998</p>
<p>The class synopses for classes <tt>codecvt&lt;&gt;</tt> (22.2.1.5)
and <tt>codecvt_byname&lt;&gt;</tt> (22.2.1.6) say that the first
parameter of the member functions <tt>length</tt> and
<tt>do_length</tt> is of type <tt>const stateT&amp;</tt>. The member
function descriptions, however (22.2.1.5.1, paragraph 6; 22.2.1.5.2,
paragraph 9) say that the type is <tt>stateT&amp;</tt>.  Either the
synopsis or the summary must be changed. </p>

<p>If (as I believe) the member function descriptions are correct,
then we must also add text saying how <tt>do_length</tt> changes its
<tt>stateT</tt> argument. </p>
<p><b>Proposed resolution:</b></p>
<p>In 22.2.1.5 <a href="lib-locales.html#lib.locale.codecvt"> [lib.locale.codecvt]</a>, and also in 22.2.1.6 <a href="lib-locales.html#lib.locale.codecvt.byname"> [lib.locale.codecvt.byname]</a>,
change the <tt>stateT</tt> argument type on both member
<tt>length()</tt> and member <tt>do_length()</tt> from </p>

<blockquote>
  <p><tt>const stateT&amp;</tt></p>
</blockquote>

<p>to</p>

<blockquote>
  <p><tt>stateT&amp;</tt></p>
</blockquote>

<p>In 22.2.1.5.2 <a href="lib-locales.html#lib.locale.codecvt.virtuals"> [lib.locale.codecvt.virtuals]</a>, add to the definition for member
<tt>do_length</tt> a paragraph:</p>

<blockquote>
  <p>Effects: The effect on the <tt>state</tt> argument is ``as if''
  it called <tt>do_in(state, from, from_end, from, to, to+max,
  to)</tt> for <tt>to</tt> pointing to a buffer of at least
  <tt>max</tt> elements.</p>
</blockquote>
<hr>
<a name="76"><h3>76.&nbsp;Can a <tt>codecvt</tt> facet always convert one internal character at a time?</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#WP">WP</a>&nbsp; <b>Submitter:</b>&nbsp;Matt Austern&nbsp; <b>Date:</b>&nbsp;25 Sep 1998</p>
<p>This issue concerns the requirements on classes derived from
<tt>codecvt</tt>, including user-defined classes. What are the
restrictions on the conversion from external characters
(e.g. <tt>char</tt>) to internal characters (e.g. <tt>wchar_t</tt>)?
Or, alternatively, what assumptions about <tt>codecvt</tt> facets can
the I/O library make? </p>

<p>The question is whether it's possible to convert from internal
characters to external characters one internal character at a time,
and whether, given a valid sequence of external characters, it's
possible to pick off internal characters one at a time. Or, to put it
differently: given a sequence of external characters and the
corresponding sequence of internal characters, does a position in the
internal sequence correspond to some position in the external
sequence? </p>

<p>To make this concrete, suppose that <tt>[first, last)</tt> is a
sequence of <i>M</i> external characters and that <tt>[ifirst,
ilast)</tt> is the corresponding sequence of <i>N</i> internal
characters, where <i>N &gt; 1</i>. That is, <tt>my_encoding.in()</tt>,
applied to <tt>[first, last)</tt>, yields <tt>[ifirst,
ilast)</tt>. Now the question: does there necessarily exist a
subsequence of external characters, <tt>[first, last_1)</tt>, such
that the corresponding sequence of internal characters is the single
character <tt>*ifirst</tt>?
</p>

<p>(What a "no" answer would mean is that
<tt>my_encoding</tt> translates sequences only as blocks. There's a
sequence of <i>M</i> external characters that maps to a sequence of
<i>N</i> internal characters, but that external sequence has no
subsequence that maps to <i>N-1</i> internal characters.) </p>

<p>Some of the wording in the standard, such as the description of
<tt>codecvt::do_max_length</tt> (22.2.1.5.2 <a href="lib-locales.html#lib.locale.codecvt.virtuals"> [lib.locale.codecvt.virtuals]</a>,
paragraph 11) and <tt>basic_filebuf::underflow</tt> (27.8.1.4 <a href="lib-iostreams.html#lib.filebuf.virtuals"> [lib.filebuf.virtuals]</a>, paragraph 3) suggests that it must always be
possible to pick off internal characters one at a time from a sequence
of external characters. However, this is never explicitly stated one
way or the other. </p>

<p>This issue seems (and is) quite technical, but it is important if
we expect users to provide their own encoding facets. This is an area
where the standard library calls user-supplied code, so a well-defined
set of requirements for the user-supplied code is crucial. Users must
be aware of the assumptions that the library makes. This issue affects
positioning operations on <tt>basic_filebuf</tt>, unbuffered input,
and several of <tt>codecvt</tt>'s member functions. </p>
<p><b>Proposed resolution:</b></p>
<p>Add the following text as a new paragraph, following 22.2.1.5.2 <a href="lib-locales.html#lib.locale.codecvt.virtuals"> [lib.locale.codecvt.virtuals]</a> paragraph 2:</p>

<blockquote>
<p>A <tt>codecvt</tt> facet that is used by <tt>basic_filebuf</tt>
(27.8 <a href="lib-iostreams.html#lib.file.streams"> [lib.file.streams]</a>) must have the property that if</p>
<pre>
    do_out(state, from, from_end, from_next, to, to_lim, to_next)
</pre>
would return <tt>ok</tt>, where <tt>from != from_end</tt>, then 
<pre>
    do_out(state, from, from + 1, from_next, to, to_end, to_next)
</pre>
must also return <tt>ok</tt>, and that if
<pre>
    do_in(state, from, from_end, from_next, to, to_lim, to_next)
</pre>
would return <tt>ok</tt>, where <tt>to != to_lim</tt>, then
<pre>
    do_in(state, from, from_end, from_next, to, to + 1, to_next)
</pre>
<p>must also return <tt>ok</tt>.  [<i>Footnote:</i> Informally, this
means that <tt>basic_filebuf</tt> assumes that the mapping from
internal to external characters is 1 to N: a <tt>codecvt</tt> that is
used by <tt>basic_filebuf</tt> must be able to translate characters
one internal character at a time.  <i>--End Footnote</i>]</p>
</blockquote>

<p><i>[Redmond: Minor change in proposed resolution.  Original
proposed resolution talked about "success", with a parenthetical
comment that success meant returning <tt>ok</tt>.  New wording
removes all talk about "success", and just talks about the
return value.]</i></p>

<p><b>Rationale:</b></p>

  <p>The proposed resoluion says that conversions can be performed one
  internal character at a time.  This rules out some encodings that
  would otherwise be legal.  The alternative answer would mean there
  would be some internal positions that do not correspond to any
  external file position.</p>
  <p>
  An example of an encoding that this rules out is one where the
  <tt>internT</tt> and <tt>externT</tt> are of the same type, and
  where the internal sequence <tt>c1 c2</tt> corresponds to the
  external sequence <tt>c2 c1</tt>.
  </p>
  <p>It was generally agreed that <tt>basic_filebuf</tt> relies
  on this property: it was designed under the assumption that
  the external-to-internal mapping is N-to-1, and it is not clear
  that <tt>basic_filebuf</tt> is implementable without that 
  restriction.
  </p>
  <p>
  The proposed resolution is expressed as a restriction on
  <tt>codecvt</tt> when used by <tt>basic_filebuf</tt>, rather
  than a blanket restriction on all <tt>codecvt</tt> facets,
  because <tt>basic_filebuf</tt> is the only other part of the 
  library that uses <tt>codecvt</tt>.  If a user wants to define
  a <tt>codecvt</tt> facet that implements a more general N-to-M
  mapping, there is no reason to prohibit it, so long as the user
  does not expect <tt>basic_filebuf</tt> to be able to use it.
  </p>
<hr>
<a name="78"><h3>78.&nbsp;Typo: event_call_back</h3></a><p><b>Section:</b>&nbsp;27.4.2 <a href="lib-iostreams.html#lib.ios.base"> [lib.ios.base]</a>&nbsp; <b>Status:</b>&nbsp;<a href="lwg-active.html#TC">TC</a>&nbsp; <b>Submitter:</b>&nbsp;Nico Josuttis&nbsp; <b>Date:</b>&nbsp;29 Sep 1998</p>
<p>typo: event_call_back should be event_callback &nbsp; </p>
<p><b>Proposed resolution:</b></p>
<p>In the 27.4.2 <a href="lib-iostreams.html#lib.ios.base"> [lib.ios.base]</a> synopsis change
"event_call_back" to "event_callback". </p>
<hr>
<a name="79"><h3>79.&nbsp;Inconsistent declaration of polar()</h3></a><p><b>Section:</b>&nbsp;26.2.1 <a href="lib-numerics.html#lib.complex.synopsis"> [lib.complex.synopsis]</a>, 26.2.7 <a href="lib-numerics.html#lib.complex.value.ops"> [lib.complex.value.ops]</a>&nbsp; <b>Status:</b>&nbsp;<a href="lwg-active.html#TC">TC</a>&nbsp; <b>Submitter:</b>&nbsp;Nico Josuttis&nbsp; <b>Date:</b>&nbsp;29 Sep 1998</p>
<p>In 26.2.1 <a href="lib-numerics.html#lib.complex.synopsis"> [lib.complex.synopsis]</a> polar is declared as follows:</p>
<pre>   template&lt;class T&gt; complex&lt;T&gt; polar(const T&amp;, const T&amp;); </pre>

<p>In 26.2.7 <a href="lib-numerics.html#lib.complex.value.ops"> [lib.complex.value.ops]</a> it is declared as follows:</p>
<pre>   template&lt;class T&gt; complex&lt;T&gt; polar(const T&amp; rho, const T&amp; theta = 0); </pre>

<p>Thus whether the second parameter is optional is not clear. </p>
<p><b>Proposed resolution:</b></p>
<p>In 26.2.1 <a href="lib-numerics.html#lib.complex.synopsis"> [lib.complex.synopsis]</a> change:</p>
<pre>   template&lt;class T&gt; complex&lt;T&gt; polar(const T&amp;, const T&amp;);</pre>

<p>to:</p>
<pre>   template&lt;class T&gt; complex&lt;T&gt; polar(const T&amp; rho, const T&amp; theta = 0); </pre>
<hr>
<a name="80"><h3>80.&nbsp;Global Operators of complex declared twice</h3></a><p><b>Section:</b>&nbsp;26.2.1 <a href="lib-numerics.html#lib.complex.synopsis"> [lib.complex.synopsis]</a>, 26.2.2 <a href="lib-numerics.html#lib.complex"> [lib.complex]</a>&nbsp; <b>Status:</b>&nbsp;<a href="lwg-active.html#TC">TC</a>&nbsp; <b>Submitter:</b>&nbsp;Nico Josuttis&nbsp; <b>Date:</b>&nbsp;29 Sep 1998</p>
<p>Both 26.2.1 and 26.2.2 contain declarations of global operators for
class complex. This redundancy should be removed.</p>
<p><b>Proposed resolution:</b></p>
<p>Reduce redundancy according to the general style of the standard. </p>
<hr>
<a name="83"><h3>83.&nbsp;String::npos vs. string::max_size()</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#TC">TC</a>&nbsp; <b>Submitter:</b>&nbsp;Nico Josuttis&nbsp; <b>Date:</b>&nbsp;29 Sep 1998</p>
<p>Many string member functions throw if size is getting or exceeding
npos. However, I wonder why they don't throw if size is getting or
exceeding max_size() instead of npos.  May be npos is known at compile
time, while max_size() is known at runtime. However, what happens if
size exceeds max_size() but not npos, then? It seems the standard
lacks some clarifications here.</p>
<p><b>Proposed resolution:</b></p>
<p>After 21.3 <a href="lib-strings.html#lib.basic.string"> [lib.basic.string]</a> paragraph 4 ("The functions
described in this clause...") add a new paragraph:</p>

<blockquote>
  <p>For any string operation, if as a result of the operation, <tt> size()</tt> would exceed
  <tt> max_size()</tt> then
  the operation throws <tt>length_error</tt>.</p>
</blockquote>
<p><b>Rationale:</b></p>
<p>The LWG believes length_error is the correct exception to throw.</p>
<hr>
<a name="86"><h3>86.&nbsp;String constructors don't describe exceptions</h3></a><p><b>Section:</b>&nbsp;21.3.1 <a href="lib-strings.html#lib.string.cons"> [lib.string.cons]</a>&nbsp; <b>Status:</b>&nbsp;<a href="lwg-active.html#TC">TC</a>&nbsp; <b>Submitter:</b>&nbsp;Nico Josuttis&nbsp; <b>Date:</b>&nbsp;29 Sep 1998</p>
<p>The constructor from a range:</p>

<pre>template&lt;class InputIterator&gt; 
         basic_string(InputIterator begin, InputIterator end, 
                      const Allocator&amp; a = Allocator());</pre>

<p>lacks a throws clause. However, I would expect that it throws
according to the other constructors if the numbers of characters in
the range equals npos (or exceeds max_size(), see above). </p>
<p><b>Proposed resolution:</b></p>
<p>In 21.3.1 <a href="lib-strings.html#lib.string.cons"> [lib.string.cons]</a>, Strike throws paragraphs for
constructors which say "Throws: length_error if n ==
npos."</p>
<p><b>Rationale:</b></p>
<p>Throws clauses for length_error if n == npos are no longer needed
because they are subsumed by the general wording added by the
resolution for issue <a href="lwg-defects.html#83">83</a>.</p>
<hr>
<a name="90"><h3>90.&nbsp;Incorrect description of operator &gt;&gt; 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#TC">TC</a>&nbsp; <b>Submitter:</b>&nbsp;Nico Josuttis&nbsp; <b>Date:</b>&nbsp;29 Sep 1998</p>
<p>The effect of operator &gt;&gt; for strings contain the following item:</p>

<p>&nbsp;&nbsp;&nbsp; <tt>isspace(c,getloc())</tt> is true for the next available input
character c.</p>

<p>Here <tt>getloc()</tt> has to be replaced by <tt>is.getloc()</tt>. </p>
<p><b>Proposed resolution:</b></p>
<p>In 21.3.7.9 <a href="lib-strings.html#lib.string.io"> [lib.string.io]</a> paragraph 1 Effects clause replace:</p>

<blockquote>
  <p><tt>isspace(c,getloc())</tt> is true for the next available input character c.</p>
</blockquote>

<p>with:</p>

<blockquote>
  <p><tt>isspace(c,is.getloc())</tt> is true for the next available input character c.</p>
</blockquote>
<hr>
<a name="91"><h3>91.&nbsp;Description of operator&gt;&gt; and getline() for string&lt;&gt; might cause endless loop</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#WP">WP</a>&nbsp; <b>Submitter:</b>&nbsp;Nico Josuttis&nbsp; <b>Date:</b>&nbsp;29 Sep 1998</p>
<p>Operator &gt;&gt; and getline() for strings read until eof()
in the input stream is true. However, this might never happen, if the
stream can't read anymore without reaching EOF. So shouldn't it be
changed into that it reads until !good() ? </p>
<p><b>Proposed resolution:</b></p>
<p>In 21.3.7.9 <a href="lib-strings.html#lib.string.io"> [lib.string.io]</a>, paragraph 1, replace:</p>
<blockquote>
Effects: Begins by constructing a sentry object k as if k were
constructed by typename basic_istream&lt;charT,traits&gt;::sentry k( is). If
bool( k) is true, it calls str.erase() and then extracts characters
from is and appends them to str as if by calling str.append(1, c). If
is.width() is greater than zero, the maximum number n of characters
appended is is.width(); otherwise n is str.max_size(). Characters are
extracted and appended until any of the following occurs:
</blockquote>
<p>with:</p>
<blockquote>
Effects: Behaves as a formatted input function (27.6.1.2.1 <a href="lib-iostreams.html#lib.istream.formatted.reqmts"> [lib.istream.formatted.reqmts]</a>).  After constructing a sentry object, if the
sentry converts to true, calls str.erase() and then extracts
characters from is and appends them to str as if by calling
str.append(1,c). If is.width() is greater than zero, the maximum
number n of characters appended is is.width(); otherwise n is
str.max_size(). Characters are extracted and appended until any of the
following occurs:
</blockquote>

<p>In 21.3.7.9 <a href="lib-strings.html#lib.string.io"> [lib.string.io]</a>, paragraph 6, replace</p>
<blockquote>
Effects: Begins by constructing a sentry object k as if by typename
basic_istream&lt;charT,traits&gt;::sentry k( is, true). If bool( k) is true,
it calls str.erase() and then extracts characters from is and appends
them to str as if by calling str.append(1, c) until any of the
following occurs:
</blockquote>
<p>with:</p>
<blockquote>
Effects: Behaves as an unformatted input function (27.6.1.3 <a href="lib-iostreams.html#lib.istream.unformatted"> [lib.istream.unformatted]</a>), except that it does not affect the value returned
by subsequent calls to basic_istream&lt;&gt;::gcount().  After
constructing a sentry object, if the sentry converts to true, calls
str.erase() and then extracts characters from is and appends them to
str as if by calling str.append(1,c) until any of the following
occurs:
</blockquote>

<p><i>[Redmond: Made changes in proposed resolution.  <tt>operator&gt;&gt;</tt>
should be a formatted input function, not an unformatted input function.
<tt>getline</tt> should not be required to set <tt>gcount</tt>, since
there is no mechanism for <tt>gcount</tt> to be set except by one of
<tt>basic_istream</tt>'s member functions.]</i></p>

<p><i>[Cura&ccedil;ao: Nico agrees with proposed resolution.]</i></p>

<p><b>Rationale:</b></p>
<p>The real issue here is whether or not these string input functions
get their characters from a streambuf, rather than by calling an
istream's member functions, a streambuf signals failure either by
returning eof or by throwing an exception; there are no other
possibilities.  The proposed resolution makes it clear that these two
functions do get characters from a streambuf.</p>
<hr>
<a name="92"><h3>92.&nbsp;Incomplete Algorithm Requirements</h3></a><p><b>Section:</b>&nbsp;25 <a href="lib-algorithms.html#lib.algorithms"> [lib.algorithms]</a>&nbsp; <b>Status:</b>&nbsp;<a href="lwg-active.html#WP">WP</a>&nbsp; <b>Submitter:</b>&nbsp;Nico Josuttis&nbsp; <b>Date:</b>&nbsp;29 Sep 1998</p>
<p>The standard does not state, how often a function object is copied,
called, or the order of calls inside an algorithm. This may lead to
surprising/buggy behavior. Consider the following example: </p>

<pre>class Nth {    // function object that returns true for the nth element 
  private: 
    int nth;     // element to return true for 
    int count;   // element counter 
  public: 
    Nth (int n) : nth(n), count(0) { 
    } 
    bool operator() (int) { 
        return ++count == nth; 
    } 
}; 
.... 
// remove third element 
    list&lt;int&gt;::iterator pos; 
    pos = remove_if(coll.begin(),coll.end(),  // range 
                    Nth(3)),                  // remove criterion 
    coll.erase(pos,coll.end()); </pre>

<p>This call, in fact removes the 3rd <b>AND the 6th</b> element. This
happens because the usual implementation of the algorithm copies the
function object internally: </p>

<pre>template &lt;class ForwIter, class Predicate&gt; 
ForwIter std::remove_if(ForwIter beg, ForwIter end, Predicate op) 
{ 
    beg = find_if(beg, end, op); 
    if (beg == end) { 
        return beg; 
    } 
    else { 
        ForwIter next = beg; 
        return remove_copy_if(++next, end, beg, op); 
    } 
} </pre>

<p>The algorithm uses find_if() to find the first element that should
be removed. However, it then uses a copy of the passed function object
to process the resulting elements (if any). Here, Nth is used again
and removes also the sixth element. This behavior compromises the
advantage of function objects being able to have a state. Without any
cost it could be avoided (just implement it directly instead of
calling find_if()). </p>
<p><b>Proposed resolution:</b></p>

<p>Add a new paragraph following 25 <a href="lib-algorithms.html#lib.algorithms"> [lib.algorithms]</a> paragraph 8:</p>
<blockquote>
[Note: Unless otherwise specified, algorithms that take function
objects as arguments are permitted to copy those function objects
freely.  Programmers for whom object identity is important should
consider using a wrapper class that points to a noncopied
implementation object, or some equivalent solution.]
</blockquote>

<p><i>[Dublin: Pete Becker felt that this may not be a defect,
but rather something that programmers need to be educated about.
There was discussion of adding wording to the effect that the number
and order of calls to function objects, including predicates, not
affect the behavior of the function object.]</i></p>

<p><i>[Pre-Kona: Nico comments: It seems the problem is that we don't
have a clear statement of "predicate" in the
standard. People including me seemed to think "a function
returning a Boolean value and being able to be called by an STL
algorithm or be used as sorting criterion or ... is a
predicate". But a predicate has more requirements: It should
never change its behavior due to a call or being copied. IMHO we have
to state this in the standard. If you like, see section 8.1.4 of my
library book for a detailed discussion.]</i></p>

<p><i>[Kona: Nico will provide wording to the effect that "unless
otherwise specified, the number of copies of and calls to function
objects by algorithms is unspecified".&nbsp; Consider placing in
25 <a href="lib-algorithms.html#lib.algorithms"> [lib.algorithms]</a> after paragraph 9.]</i></p>

<p><i>[Santa Cruz: The standard doesn't currently guarantee that
  functions object won't be copied, and what isn't forbidden is
  allowed.  It is believed (especially since implementations that were
  written in concert with the standard do make copies of function
  objects) that this was intentional.  Thus, no normative change is
  needed.  What we should put in is a non-normative note suggesting to
  programmers that if they want to guarantee the lack of copying they
  should use something like the <tt>ref</tt> wrapper.]</i></p>

<p><i>[Oxford: Matt provided wording.]</i></p>


<hr>
<a name="98"><h3>98.&nbsp;Input iterator requirements are badly written</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#WP">WP</a>&nbsp; <b>Submitter:</b>&nbsp;AFNOR&nbsp; <b>Date:</b>&nbsp;7 Oct 1998</p>
<p>Table 72 in 24.1.1 <a href="lib-iterators.html#lib.input.iterators"> [lib.input.iterators]</a> specifies semantics for
<tt>*r++</tt> of:</p>

<p>&nbsp;&nbsp; <tt>{ T tmp = *r; ++r; return tmp; }</tt></p>

<p>There are two problems with this.  First, the return type is
specified to be "T", as opposed to something like "convertible to T".
This is too specific: we want to allow *r++ to return an lvalue.</p>

<p>Second, writing the semantics in terms of code misleadingly
suggests that the effects *r++ should precisely replicate the behavior
of this code, including side effects.  (Does this mean that *r++
should invoke the copy constructor exactly as many times as the sample
code above would?) See issue <a href="lwg-defects.html#334">334</a> for a similar
problem.</p>

<p><b>Proposed resolution:</b></p>
In Table 72 in 24.1.1 <a href="lib-iterators.html#lib.input.iterators"> [lib.input.iterators]</a>, change the return type
for <tt>*r++</tt> from <tt>T</tt> to "convertible to T".
<p><b>Rationale:</b></p>
<p>This issue has two parts: the return type, and the number of times
  the copy constructor is invoked.</p>

<p>The LWG believes the the first part is a real issue.  It's
  inappropriate for the return type to be specified so much more
  precisely for *r++ than it is for *r.  In particular, if r is of
  (say) type <tt>int*</tt>, then *r++ isn't <tt>int</tt>,
  but <tt>int&amp;</tt>.</p>

<p>The LWG does not believe that the number of times the copy
  constructor is invoked is a real issue.  This can vary in any case,
  because of language rules on copy constructor elision.  That's too
  much to read into these semantics clauses.</p>

<p>Additionally, as Dave Abrahams pointed out (c++std-lib-13703): since 
   we're told (24.1/3) that forward iterators satisfy all the requirements
   of input iterators, we can't impose any requirements in the Input
   Iterator requirements table that forward iterators don't satisfy.</p>
<hr>
<a name="103"><h3>103.&nbsp;set::iterator is required to be modifiable, but this allows modification of keys</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#WP">WP</a>&nbsp; <b>Submitter:</b>&nbsp;AFNOR&nbsp; <b>Date:</b>&nbsp;7 Oct 1998</p>
<p>Set::iterator is described as implementation-defined with a
reference to the container requirement; the container requirement says
that const_iterator is an iterator pointing to const T and iterator an
iterator pointing to T.</p>

<p>23.1.2 paragraph 2 implies that the keys should not be modified to
break the ordering of elements. But that is not clearly
specified. Especially considering that the current standard requires
that iterator for associative containers be different from
const_iterator. Set, for example, has the following: </p>

<p><tt>typedef implementation defined iterator;<br>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; // See _lib.container.requirements_</tt></p>

<p>23.1 <a href="lib-containers.html#lib.container.requirements"> [lib.container.requirements]</a> actually requires that iterator type pointing
to T (table 65). Disallowing user modification of keys by changing the
standard to require an iterator for associative container to be the
same as const_iterator would be overkill since that will unnecessarily
significantly restrict the usage of associative container. A class to
be used as elements of set, for example, can no longer be modified
easily without either redesigning the class (using mutable on fields
that have nothing to do with ordering), or using const_cast, which
defeats requiring iterator to be const_iterator. The proposed solution
goes in line with trusting user knows what he is doing. </p>

<p><b>Other Options Evaluated:</b> </p>

<p>Option A.&nbsp;&nbsp; In 23.1.2 <a href="lib-containers.html#lib.associative.reqmts"> [lib.associative.reqmts]</a>, paragraph 2, after
first sentence, and before "In addition,...", add one line:
</p>

<blockquote>
  <p>Modification of keys shall not change their strict weak ordering. </p>
</blockquote>

<p>Option B.&nbsp;Add three new sentences to 23.1.2 <a href="lib-containers.html#lib.associative.reqmts"> [lib.associative.reqmts]</a>:</p>

<blockquote>
  <p>At the end of paragraph 5: "Keys in an associative container
  are immutable." At the end of paragraph 6: "For
  associative containers where the value type is the same as the key
  type, both <tt>iterator</tt> and <tt>const_iterator</tt> are
  constant iterators. It is unspecified whether or not
  <tt>iterator</tt> and <tt>const_iterator</tt> are the same
  type."</p>
</blockquote>

<p>Option C.&nbsp;To 23.1.2 <a href="lib-containers.html#lib.associative.reqmts"> [lib.associative.reqmts]</a>, paragraph 3, which
currently reads:</p>

<blockquote>
  <p>The phrase ``equivalence of keys'' means the equivalence relation imposed by the
  comparison and not the operator== on keys. That is, two keys k1 and k2 in the same
  container are considered to be equivalent if for the comparison object comp, comp(k1, k2)
  == false &amp;&amp; comp(k2, k1) == false.</p>
</blockquote>

<p>&nbsp; add the following:</p>

<blockquote>
  <p>For any two keys k1 and k2 in the same container, comp(k1, k2) shall return the same
  value whenever it is evaluated. [Note: If k2 is removed from the container and later
  reinserted, comp(k1, k2) must still return a consistent value but this value may be
  different than it was the first time k1 and k2 were in the same container. This is
  intended to allow usage like a string key that contains a filename, where comp compares
  file contents; if k2 is removed, the file is changed, and the same k2 (filename) is
  reinserted, comp(k1, k2) must again return a consistent value but this value may be
  different than it was the previous time k2 was in the container.]</p>
</blockquote>
<p><b>Proposed resolution:</b></p>
<p>Add the following to 23.1.2 <a href="lib-containers.html#lib.associative.reqmts"> [lib.associative.reqmts]</a> at
the indicated location:</p>

<blockquote>
  <p>At the end of paragraph 3: "For any two keys k1 and k2 in the same container,
  calling comp(k1, k2) shall always return the same
  value."</p>
  <p>At the end of paragraph 5: "Keys in an associative container are immutable."</p>
  <p>At the end of paragraph 6: "For associative containers where the value type is the
  same as the key type, both <tt>iterator</tt> and <tt>const_iterator</tt> are constant
  iterators. It is unspecified whether or not <tt>iterator</tt> and <tt>const_iterator</tt>
  are the same type."</p>
</blockquote>
<p><b>Rationale:</b></p>
<p>Several arguments were advanced for and against allowing set elements to be
mutable as long as the ordering was not effected. The argument which swayed the
LWG was one of safety; if elements were mutable, there would be no compile-time
way to detect of a simple user oversight which caused ordering to be
modified.  There was a report that this had actually happened in practice,
and had been painful to diagnose.  If users need to modify elements,
it is possible to use mutable members or const_cast.</p>

<p>Simply requiring that keys be immutable is not sufficient, because the comparison
object may indirectly (via pointers) operate on values outside of the keys.</p>

<p>
The types <tt>iterator</tt> and <tt>const_iterator</tt> are permitted
to be different types to allow for potential future work in which some
member functions might be overloaded between the two types.  No such
member functions exist now, and the LWG believes that user functionality
will not be impaired by permitting the two types to be the same.  A
function that operates on both iterator types can be defined for 
<tt>const_iterator</tt> alone, and can rely on the automatic
conversion from <tt>iterator</tt> to <tt>const_iterator</tt>.
</p>

<p><i>[Tokyo: The LWG crafted the proposed resolution and rationale.]</i></p>
<hr>
<a name="106"><h3>106.&nbsp;Numeric library private members are implementation defined</h3></a><p><b>Section:</b>&nbsp;26.3.5 <a href="lib-numerics.html#lib.template.slice.array"> [lib.template.slice.array]</a>&nbsp; <b>Status:</b>&nbsp;<a href="lwg-active.html#TC">TC</a>&nbsp; <b>Submitter:</b>&nbsp;AFNOR&nbsp; <b>Date:</b>&nbsp;7 Oct 1998</p>
<p>This is the only place in the whole standard where the implementation has to document
something private.</p>
<p><b>Proposed resolution:</b></p>
<p>
Remove the comment which says "// remainder implementation defined" from:
</p>

<ul>
  <li>26.3.5 <a href="lib-numerics.html#lib.template.slice.array"> [lib.template.slice.array]</a>
</li>
  <li>26.3.7 <a href="lib-numerics.html#lib.template.gslice.array"> [lib.template.gslice.array]</a>
</li>
  <li>26.3.8 <a href="lib-numerics.html#lib.template.mask.array"> [lib.template.mask.array]</a>
</li>
  <li>26.3.9 <a href="lib-numerics.html#lib.template.indirect.array"> [lib.template.indirect.array]</a>
</li>
</ul>
<hr>
<a name="108"><h3>108.&nbsp;Lifetime of exception::what() return unspecified</h3></a><p><b>Section:</b>&nbsp;18.6.1 <a href="lib-support.html#lib.exception"> [lib.exception]</a>&nbsp; <b>Status:</b>&nbsp;<a href="lwg-active.html#TC">TC</a>&nbsp; <b>Submitter:</b>&nbsp;AFNOR&nbsp; <b>Date:</b>&nbsp;7 Oct 1998</p>
<p>In 18.6.1, paragraphs 8-9, the lifetime of the return value of
exception::what() is left unspecified. This issue has implications
with exception safety of exception handling: some exceptions should
not throw bad_alloc.</p>
<p><b>Proposed resolution:</b></p>
<p>Add to 18.6.1 <a href="lib-support.html#lib.exception"> [lib.exception]</a> paragraph 9 (exception::what notes
clause) the sentence:</p>

<blockquote>
  <p>The return value remains valid until the exception object from which it is obtained is
  destroyed or a non-const member function of the exception object is called.</p>
</blockquote>
<p><b>Rationale:</b></p>
<p>If an exception object has non-const members, they may be used
to set internal state that should affect the contents of the string
returned by <tt>what()</tt>.
</p>
<hr>
<a name="109"><h3>109.&nbsp;Missing binders for non-const sequence elements</h3></a><p><b>Section:</b>&nbsp;20.3.6 <a href="lib-utilities.html#lib.binders"> [lib.binders]</a>&nbsp; <b>Status:</b>&nbsp;<a href="lwg-active.html#WP">WP</a>&nbsp; <b>Submitter:</b>&nbsp;Bjarne Stroustrup&nbsp; <b>Date:</b>&nbsp;7 Oct 1998</p>

<p>There are no versions of binders that apply to non-const elements
of a sequence. This makes examples like for_each() using bind2nd() on
page 521 of "The C++ Programming Language (3rd)"
non-conforming. Suitable versions of the binders need to be added.</p>

<p>Further discussion from Nico:</p>

<p>What is probably meant here is shown in the following example:</p>

<pre>class Elem { 
  public: 
    void print (int i) const { } 
    void modify (int i) { } 
}; </pre>
<pre>int main() 
{ 
    vector&lt;Elem&gt; coll(2); 
    for_each (coll.begin(), coll.end(), bind2nd(mem_fun_ref(&amp;Elem::print),42));    // OK 
    for_each (coll.begin(), coll.end(), bind2nd(mem_fun_ref(&amp;Elem::modify),42));   // ERROR 
}</pre>

<p>The error results from the fact that bind2nd() passes its first
argument (the argument of the sequence) as constant reference. See the
following typical implementation:</p>

<blockquote>
  <pre>template &lt;class Operation&gt; 
class binder2nd 
  : public unary_function&lt;typename Operation::first_argument_type, 
                          typename Operation::result_type&gt; { 
protected: 
  Operation op; 
  typename Operation::second_argument_type value; 
public: 
  binder2nd(const Operation&amp; o, 
            const typename Operation::second_argument_type&amp; v) 
      : op(o), value(v) {} </pre>
  <pre> typename Operation::result_type 
  operator()(const typename Operation::first_argument_type&amp; x) const { 
    return op(x, value); 
  } 
};</pre>
</blockquote>

<p>The solution is to overload operator () of bind2nd for non-constant arguments:</p>

<blockquote>
  <pre>template &lt;class Operation&gt; 
class binder2nd 
  : public unary_function&lt;typename Operation::first_argument_type, 
                          typename Operation::result_type&gt; { 
protected: 
  Operation op; 
  typename Operation::second_argument_type value; 
public: 
  binder2nd(const Operation&amp; o, 
            const typename Operation::second_argument_type&amp; v) 
      : op(o), value(v) {} </pre>
  <pre> typename Operation::result_type 
  operator()(const typename Operation::first_argument_type&amp; x) const { 
    return op(x, value); 
  } 
  typename Operation::result_type 
  operator()(typename Operation::first_argument_type&amp; x) const { 
    return op(x, value); 
  } 
};</pre>
</blockquote>
<p><b>Proposed resolution:</b></p>

<p><b>Howard believes there is a flaw</b> in this resolution.
See c++std-lib-9127.  We may need to reopen this issue.</p>

<p>In 20.3.6.1 <a href="lib-utilities.html#lib.binder.1st"> [lib.binder.1st]</a> in the declaration of binder1st after:</p>
<blockquote>
  <p><tt>typename Operation::result_type<br>
  &nbsp;operator()(const typename Operation::second_argument_type&amp; x) const;</tt></p>
</blockquote>
<p>insert:</p>
<blockquote>
  <p><tt>typename Operation::result_type<br>
  &nbsp;operator()(typename Operation::second_argument_type&amp; x) const;</tt></p>
</blockquote>
<p>In 20.3.6.3 <a href="lib-utilities.html#lib.binder.2nd"> [lib.binder.2nd]</a> in the declaration of binder2nd after:</p>
<blockquote>
  <p><tt>typename Operation::result_type<br>
  &nbsp;operator()(const typename Operation::first_argument_type&amp; x) const;</tt></p>
</blockquote>
<p>insert:</p>
<blockquote>
  <p><tt>typename Operation::result_type<br>
  &nbsp;operator()(typename Operation::first_argument_type&amp; x) const;</tt></p>
</blockquote>

<p><i>[Kona: The LWG discussed this at some length.It was agreed that
this is a mistake in the design, but there was no consensus on whether
it was a defect in the Standard.  Straw vote: NAD - 5.  Accept
proposed resolution - 3.  Leave open - 6.]</i></p>

<p><i>[Copenhagen: It was generally agreed that this was a defect.
Strap poll: NAD - 0.  Accept proposed resolution - 10. 
Leave open - 1.]</i></p>

<hr>
<a name="110"><h3>110.&nbsp;istreambuf_iterator::equal not const</h3></a><p><b>Section:</b>&nbsp;24.5.3 <a href="lib-iterators.html#lib.istreambuf.iterator"> [lib.istreambuf.iterator]</a>, 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#TC">TC</a>&nbsp; <b>Submitter:</b>&nbsp;Nathan Myers&nbsp; <b>Date:</b>&nbsp;15 Oct 1998</p>
<p>Member istreambuf_iterator&lt;&gt;::equal is not declared
"const", yet 24.5.3.6 <a href="lib-iterators.html#lib.istreambuf.iterator::op=="> [lib.istreambuf.iterator::op==]</a> says that operator==,
which is const, calls it. This is contradictory. </p>
<p><b>Proposed resolution:</b></p>
<p>In 24.5.3 <a href="lib-iterators.html#lib.istreambuf.iterator"> [lib.istreambuf.iterator]</a> and also in 24.5.3.5 <a href="lib-iterators.html#lib.istreambuf.iterator::equal"> [lib.istreambuf.iterator::equal]</a>,
replace:</p>

<blockquote>
  <pre>bool equal(istreambuf_iterator&amp; b);</pre>
</blockquote>

<p>with:</p>

<blockquote>
  <pre>bool equal(const istreambuf_iterator&amp; b) const;</pre>
</blockquote>
<hr>
<a name="112"><h3>112.&nbsp;Minor typo in <tt>ostreambuf_iterator</tt> constructor</h3></a><p><b>Section:</b>&nbsp;24.5.4.1 <a href="lib-iterators.html#lib.ostreambuf.iter.cons"> [lib.ostreambuf.iter.cons]</a>&nbsp; <b>Status:</b>&nbsp;<a href="lwg-active.html#TC">TC</a>&nbsp; <b>Submitter:</b>&nbsp;Matt Austern&nbsp; <b>Date:</b>&nbsp;20 Oct 1998</p>
<p>The <b>requires</b> clause for <tt>ostreambuf_iterator</tt>'s
constructor from an <tt>ostream_type</tt> (24.5.4.1, paragraph 1)
reads "<i>s</i> is not null". However, <i>s</i> is a
reference, and references can't be null. </p>
<p><b>Proposed resolution:</b></p>
<p>In 24.5.4.1 <a href="lib-iterators.html#lib.ostreambuf.iter.cons"> [lib.ostreambuf.iter.cons]</a>:</p>

<p>Move the current paragraph 1, which reads "Requires: s is not
null.", from the first constructor to the second constructor.</p>

<p>Insert a new paragraph 1 Requires clause for the first constructor
reading:</p>

<blockquote>
  <p><b>Requires</b>: <tt>s.rdbuf()</tt> is not null.</p>
</blockquote>
<hr>
<a name="114"><h3>114.&nbsp;Placement forms example in error twice</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#TC">TC</a>&nbsp; <b>Submitter:</b>&nbsp;Steve Clamage&nbsp; <b>Date:</b>&nbsp;28 Oct 1998</p>
<p>Section 18.4.1.3 contains the following example: </p>

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

<p>First code line: "place" need not have any special alignment, and the
following constructor could fail due to misaligned data.</p>

<p>Second code line: Aren't the parens on Something() incorrect?&nbsp; [Dublin: the LWG
believes the () are correct.]</p>

<p>Examples are not normative, but nevertheless should not show code that is invalid or
likely to fail.</p>
<p><b>Proposed resolution:</b></p>
<p>Replace the <u> first line of code</u> in the example in 
18.4.1.3 <a href="lib-support.html#lib.new.delete.placement"> [lib.new.delete.placement]</a> with:
</p>

<blockquote>
  <pre>void* place = operator new(sizeof(Something));</pre>
</blockquote>
<hr>
<a name="115"><h3>115.&nbsp;Typo in strstream constructors</h3></a><p><b>Section:</b>&nbsp;D.7.4.1 <a href="future.html#depr.strstream.cons"> [depr.strstream.cons]</a>&nbsp; <b>Status:</b>&nbsp;<a href="lwg-active.html#TC">TC</a>&nbsp; <b>Submitter:</b>&nbsp;Steve Clamage&nbsp; <b>Date:</b>&nbsp;2 Nov 1998</p>
<p>D.7.4.1 strstream constructors paragraph 2 says: </p>

<blockquote>
  <p>Effects: Constructs an object of class strstream, initializing the base class with
  iostream(&amp; sb) and initializing sb with one of the two constructors: </p>
  <p>- If mode&amp;app==0, then s shall designate the first element of an array of n
  elements. The constructor is strstreambuf(s, n, s). </p>
  <p>- If mode&amp;app==0, then s shall designate the first element of an array of n
  elements that contains an NTBS whose first element is designated by s. The constructor is
  strstreambuf(s, n, s+std::strlen(s)).</p>
</blockquote>

<p>Notice the second condition is the same as the first. I think the second condition
should be "If mode&amp;app==app", or "mode&amp;app!=0", meaning that
the append bit is set.</p>
<p><b>Proposed resolution:</b></p>
<p>In D.7.3.1 <a href="future.html#depr.ostrstream.cons"> [depr.ostrstream.cons]</a> paragraph 2 and D.7.4.1 <a href="future.html#depr.strstream.cons"> [depr.strstream.cons]</a>
paragraph 2, change the first condition to <tt>(mode&amp;app)==0</tt>
and the second condition to <tt>(mode&amp;app)!=0</tt>.</p>
<hr>
<a name="117"><h3>117.&nbsp;<tt>basic_ostream</tt> uses nonexistent <tt>num_put</tt> member functions</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#WP">WP</a>&nbsp; <b>Submitter:</b>&nbsp;Matt Austern&nbsp; <b>Date:</b>&nbsp;20 Nov 1998</p>
<p>The <b>effects</b> clause for numeric inserters says that
insertion of a value <tt>x</tt>, whose type is either <tt>bool</tt>,
<tt>short</tt>, <tt>unsigned short</tt>, <tt>int</tt>, <tt>unsigned
int</tt>, <tt>long</tt>, <tt>unsigned long</tt>, <tt>float</tt>,
<tt>double</tt>, <tt>long double</tt>, or <tt>const void*</tt>, is
delegated to <tt>num_put</tt>, and that insertion is performed as if
through the following code fragment: </p>

<pre>bool failed = use_facet&lt;
   num_put&lt;charT,ostreambuf_iterator&lt;charT,traits&gt; &gt; 
   &gt;(getloc()).put(*this, *this, fill(), val). failed();</pre>

<p>This doesn't work, because <tt>num_put&lt;&gt;</tt>::put is only
overloaded for the types <tt>bool</tt>, <tt>long</tt>, <tt>unsigned
long</tt>, <tt>double</tt>, <tt>long double</tt>, and <tt>const
void*</tt>. That is, the code fragment in the standard is incorrect
(it is diagnosed as ambiguous at compile time) for the types
<tt>short</tt>, <tt>unsigned short</tt>, <tt>int</tt>, <tt>unsigned
int</tt>, and <tt>float</tt>. </p>

<p>We must either add new member functions to <tt>num_put</tt>, or
else change the description in <tt>ostream</tt> so that it only calls
functions that are actually there. I prefer the latter. </p>
<p><b>Proposed resolution:</b></p>
<p>Replace 27.6.2.5.2, paragraph 1 with the following: </p>

<blockquote>
<p>
The classes num_get&lt;&gt; and num_put&lt;&gt; handle locale&shy;dependent numeric
formatting and parsing.  These inserter functions use the imbued
locale value to perform numeric formatting.  When val is of type bool,
long, unsigned long, double, long double, or const void*, the
formatting conversion occurs as if it performed the following code
fragment:
</p>

<pre>
bool failed = use_facet&lt;
   num_put&lt;charT,ostreambuf_iterator&lt;charT,traits&gt; &gt;
   &gt;(getloc()).put(*this, *this, fill(), val). failed();
</pre>

<p>
When val is of type short the formatting conversion occurs as if it
performed the following code fragment:
</p>

<pre>
ios_base::fmtflags baseflags = ios_base::flags() &amp; ios_base::basefield;
bool failed = use_facet&lt;
   num_put&lt;charT,ostreambuf_iterator&lt;charT,traits&gt; &gt;
   &gt;(getloc()).put(*this, *this, fill(),
      baseflags == ios_base::oct || baseflags == ios_base::hex
         ? static_cast&lt;long&gt;(static_cast&lt;unsigned short&gt;(val))
         : static_cast&lt;long&gt;(val)). failed();
</pre>

<p>
When val is of type int the formatting conversion occurs as if it performed
the following code fragment:
</p>

<pre>
ios_base::fmtflags baseflags = ios_base::flags() &amp; ios_base::basefield;
bool failed = use_facet&lt;
   num_put&lt;charT,ostreambuf_iterator&lt;charT,traits&gt; &gt;
   &gt;(getloc()).put(*this, *this, fill(),
      baseflags == ios_base::oct || baseflags == ios_base::hex
         ? static_cast&lt;long&gt;(static_cast&lt;unsigned int&gt;(val))
         : static_cast&lt;long&gt;(val)). failed();
</pre>

<p>
When val is of type unsigned short or unsigned int the formatting conversion
occurs as if it performed the following code fragment:
</p>

<pre>
bool failed = use_facet&lt;
   num_put&lt;charT,ostreambuf_iterator&lt;charT,traits&gt; &gt;
   &gt;(getloc()).put(*this, *this, fill(), static_cast&lt;unsigned long&gt;(val)).
failed();
</pre>

<p>
When val is of type float the formatting conversion occurs as if it
performed the following code fragment:
</p>

<pre>
bool failed = use_facet&lt;
   num_put&lt;charT,ostreambuf_iterator&lt;charT,traits&gt; &gt;
   &gt;(getloc()).put(*this, *this, fill(), static_cast&lt;double&gt;(val)).
failed();
</pre>

</blockquote>

<p><i>[post-Toronto: This differs from the previous proposed
resolution; PJP provided the new wording.  The differences are in
signed short and int output.]</i></p>
<p><b>Rationale:</b></p>
<p>The original proposed resolution was to cast int and short to long,
unsigned int and unsigned short to unsigned long, and float to double,
thus ensuring that we don't try to use nonexistent num_put&lt;&gt;
member functions.  The current proposed resolution is more
complicated, but gives more expected results for hex and octal output
of signed short and signed int.  (On a system with 16-bit short, for
example, printing short(-1) in hex format should yield 0xffff.)</p>
<hr>
<a name="118"><h3>118.&nbsp;<tt>basic_istream</tt> uses nonexistent <tt>num_get</tt> member functions</h3></a><p><b>Section:</b>&nbsp;27.6.1.2.2 <a href="lib-iostreams.html#lib.istream.formatted.arithmetic"> [lib.istream.formatted.arithmetic]</a>&nbsp; <b>Status:</b>&nbsp;<a href="lwg-active.html#WP">WP</a>&nbsp; <b>Submitter:</b>&nbsp;Matt Austern&nbsp; <b>Date:</b>&nbsp;20 Nov 1998</p>
<p>Formatted input is defined for the types <tt>short</tt>, <tt>unsigned short</tt>, <tt>int</tt>,
<tt>unsigned int</tt>, <tt>long</tt>, <tt>unsigned long</tt>, <tt>float</tt>, <tt>double</tt>,
<tt>long double</tt>, <tt>bool</tt>, and <tt>void*</tt>. According to section 27.6.1.2.2,
formatted input of a value <tt>x</tt> is done as if by the following code fragment: </p>

<pre>typedef num_get&lt; charT,istreambuf_iterator&lt;charT,traits&gt; &gt; numget; 
iostate err = 0; 
use_facet&lt; numget &gt;(loc).get(*this, 0, *this, err, val); 
setstate(err);</pre>

<p>According to section 22.2.2.1.1 <a href="lib-locales.html#lib.facet.num.get.members"> [lib.facet.num.get.members]</a>, however,
<tt>num_get&lt;&gt;::get()</tt> is only overloaded for the types
<tt>bool</tt>, <tt>long</tt>, <tt>unsigned short</tt>, <tt>unsigned
int</tt>, <tt>unsigned long</tt>, <tt>unsigned long</tt>,
<tt>float</tt>, <tt>double</tt>, <tt>long double</tt>, and
<tt>void*</tt>. Comparing the lists from the two sections, we find
that 27.6.1.2.2 is using a nonexistent function for types
<tt>short</tt> and <tt>int</tt>. </p>
<p><b>Proposed resolution:</b></p>
<p>In 27.6.1.2.2 <a href="lib-iostreams.html#lib.istream.formatted.arithmetic"> [lib.istream.formatted.arithmetic]</a> Arithmetic Extractors, remove the
two lines (1st and 3rd) which read:</p>
<blockquote>
  <pre>operator&gt;&gt;(short&amp; val);
...
operator&gt;&gt;(int&amp; val);</pre>
</blockquote>

<p>And add the following at the end of that section (27.6.1.2.2) :</p>

<blockquote>
  <pre>operator&gt;&gt;(short&amp; val);</pre>
  <p>The conversion occurs as if performed by the following code fragment (using
  the same notation as for the preceding code fragment):</p>
  <pre>  typedef num_get&lt; charT,istreambuf_iterator&lt;charT,traits&gt; &gt; numget;
  iostate err = 0;
  long lval;
  use_facet&lt; numget &gt;(loc).get(*this, 0, *this, err, lval);
        if (err == 0
                &amp;&amp; (lval &lt; numeric_limits&lt;short&gt;::min() || numeric_limits&lt;short&gt;::max() &lt; lval))
                err = ios_base::failbit;
  setstate(err);</pre>
  <pre>operator&gt;&gt;(int&amp; val);</pre>
  <p>The conversion occurs as if performed by the following code fragment (using
  the same notation as for the preceding code fragment):</p>
  <pre>  typedef num_get&lt; charT,istreambuf_iterator&lt;charT,traits&gt; &gt; numget;
  iostate err = 0;
  long lval;
  use_facet&lt; numget &gt;(loc).get(*this, 0, *this, err, lval);
        if (err == 0
                &amp;&amp; (lval &lt; numeric_limits&lt;int&gt;::min() || numeric_limits&lt;int&gt;::max() &lt; lval))
                err = ios_base::failbit;
  setstate(err);</pre>
</blockquote>

<p><i>[Post-Tokyo: PJP provided the above wording.]</i></p>
<hr>
<a name="119"><h3>119.&nbsp;Should virtual functions be allowed to strengthen the exception specification?</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>&nbsp; <b>Status:</b>&nbsp;<a href="lwg-active.html#TC">TC</a>&nbsp; <b>Submitter:</b>&nbsp;Judy Ward&nbsp; <b>Date:</b>&nbsp;15 Dec 1998</p>
<p>Section 17.4.4.8 <a href="lib-intro.html#lib.res.on.exception.handling"> [lib.res.on.exception.handling]</a> states: </p>

<p>"An implementation may strengthen the exception-specification
for a function by removing listed exceptions." </p>

<p>The problem is that if an implementation is allowed to do this for
virtual functions, then a library user cannot write a class that
portably derives from that class. </p>

<p>For example, this would not compile if ios_base::failure::~failure
had an empty exception specification: </p>

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

class D : public std::ios_base::failure {
public:
        D(const std::string&amp;);
        ~D(); // error - exception specification must be compatible with 
              // overridden virtual function ios_base::failure::~failure()
};</pre>
<p><b>Proposed resolution:</b></p>
<p>Change Section 17.4.4.8 <a href="lib-intro.html#lib.res.on.exception.handling"> [lib.res.on.exception.handling]</a> from:</p>

<p>&nbsp;&nbsp;&nbsp;&nbsp; "may strengthen the
exception-specification for a function"</p>

<p>to:</p>

<p>&nbsp;&nbsp;&nbsp;&nbsp; "may strengthen the
exception-specification for a non-virtual function". </p>
<hr>
<a name="120"><h3>120.&nbsp;Can an implementor add specializations?</h3></a><p><b>Section:</b>&nbsp;17.4.3.1 <a href="lib-intro.html#lib.reserved.names"> [lib.reserved.names]</a>&nbsp; <b>Status:</b>&nbsp;<a href="lwg-active.html#WP">WP</a>&nbsp; <b>Submitter:</b>&nbsp;Judy Ward&nbsp; <b>Date:</b>&nbsp;15 Dec 1998</p>

<p>The original issue asked whether a library implementor could
specialize standard library templates for built-in types.  (This was
an issue because users are permitted to explicitly instantiate
standard library templates.)</p>

<p>Specializations are no longer a problem, because of the resolution
to core issue 259.  Under the proposed resolution, it will be legal
for a translation unit to contain both a specialization and an
explicit instantiation of the same template, provided that the
specialization comes first.  In such a case, the explicit
instantiation will be ignored.  Further discussion of library issue
120 assumes that the core 259 resolution will be adopted.</p>

<p>However, as noted in lib-7047, one piece of this issue still
remains: what happens if a standard library implementor explicitly
instantiates a standard library templates?  It's illegal for a program
to contain two different explicit instantiations of the same template
for the same type in two different translation units (ODR violation),
and the core working group doesn't believe it is practical to relax
that restriction.</p>

<p>The issue, then, is: are users allowed to explicitly instantiate
standard library templates for non-user defined types?  The status quo
answer is 'yes'.  Changing it to 'no' would give library implementors
more freedom.</p>

<p>This is an issue because, for performance reasons, library
implementors often need to explicitly instantiate standard library
templates.  (for example, std::basic_string&lt;char&gt;)  Does giving
users freedom to explicitly instantiate standard library templates for
non-user defined types make it impossible or painfully difficult for
library implementors to do this?</p>

<p>John Spicer suggests, in lib-8957, that library implementors have a
mechanism they can use for explicit instantiations that doesn't
prevent users from performing their own explicit instantiations: put
each explicit instantiation in its own object file.  (Different
solutions might be necessary for Unix DSOs or MS-Windows DLLs.)  On
some platforms, library implementors might not need to do anything
special: the "undefined behavior" that results from having two
different explicit instantiations might be harmless.</p>

<p><b>Proposed resolution:</b></p>
  <p>Append to 17.4.3.1 <a href="lib-intro.html#lib.reserved.names"> [lib.reserved.names]</a> paragraph 1: </p>
  <blockquote>
    A program may explicitly instantiate any templates in the standard
    library only if the declaration depends on the name of a user-defined
    type of external linkage and the instantiation meets the standard library
    requirements for the original template.
  </blockquote>

<p><i>[Kona: changed the wording from "a user-defined name" to "the name of
  a user-defined type"]</i></p>

<p><b>Rationale:</b></p>
<p>The LWG considered another possible resolution:</p>
<blockquote>
  <p>In light of the resolution to core issue 259, no normative changes
  in the library clauses are necessary.  Add the following non-normative
  note to the end of 17.4.3.1 <a href="lib-intro.html#lib.reserved.names"> [lib.reserved.names]</a> paragraph 1:</p>
  <blockquote>
    [<i>Note:</i> A program may explicitly instantiate standard library
    templates, even when an explicit instantiation does not depend on
    a user-defined name. <i>--end note</i>]
  </blockquote>
</blockquote>

<p>The LWG rejected this because it was believed that it would make
  it unnecessarily difficult for library implementors to write
  high-quality implementations.  A program may not include an
  explicit instantiation of the same template, for the same template
  arguments, in two different translation units.  If users are
  allowed to provide explicit instantiations of Standard Library
  templates for built-in types, then library implementors aren't,
  at least not without nonportable tricks.</p>

<p>The most serious problem is a class template that has writeable
  static member variables.  Unfortunately, such class templates are
  important and, in existing Standard Library implementations, are
  often explicitly specialized by library implementors: locale facets,
  which have a writeable static member variable <tt>id</tt>.  If a
  user's explicit instantiation collided with the implementations
  explicit instantiation, iostream initialization could cause locales
  to be constructed in an inconsistent state.</p>

<p>One proposed implementation technique was for Standard Library
  implementors to provide explicit instantiations in separate object
  files, so that they would not be picked up by the linker when the
  user also provides an explicit instantiation.  However, this
  technique only applies for Standard Library implementations that
  are packaged as static archives.  Most Standard Library
  implementations nowadays are packaged as dynamic libraries, so this
  technique would not apply.</p>

<p>The Committee is now considering standardization of dynamic
  linking.  If there are such changes in the future, it may be
  appropriate to revisit this issue later.</p>
<hr>
<a name="122"><h3>122.&nbsp;streambuf/wstreambuf description should not say they are specializations</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#TC">TC</a>&nbsp; <b>Submitter:</b>&nbsp;Judy Ward&nbsp; <b>Date:</b>&nbsp;15 Dec 1998</p>
<p>Section 27.5.2 describes the streambuf classes this way: </p>

<blockquote>

<p>The class streambuf is a specialization of the template class basic_streambuf
specialized for the type char. </p>

<p>The class wstreambuf is a specialization of the template class basic_streambuf
specialized for the type wchar_t. </p>

</blockquote>

<p>This implies that these classes must be template specializations, not typedefs. </p>

<p>It doesn't seem this was intended, since Section 27.5 has them declared as typedefs. </p>
<p><b>Proposed resolution:</b></p>
<p>Remove 27.5.2 <a href="lib-iostreams.html#lib.streambuf"> [lib.streambuf]</a> paragraphs 2 and 3 (the above two
sentences). </p>
<p><b>Rationale:</b></p>
<p>The <tt>streambuf</tt>  synopsis already has a declaration for the
typedefs and that is sufficient. </p>
<hr>
<a name="123"><h3>123.&nbsp;Should valarray helper arrays fill functions be const?</h3></a><p><b>Section:</b>&nbsp;26.3.5.4 <a href="lib-numerics.html#lib.slice.arr.fill"> [lib.slice.arr.fill]</a>, 26.3.7.4 <a href="lib-numerics.html#lib.gslice.array.fill"> [lib.gslice.array.fill]</a>, 26.3.8.4 <a href="lib-numerics.html#lib.mask.array.fill"> [lib.mask.array.fill]</a>, 26.3.9.4 <a href="lib-numerics.html#lib.indirect.array.fill"> [lib.indirect.array.fill]</a>&nbsp; <b>Status:</b>&nbsp;<a href="lwg-active.html#WP">WP</a>&nbsp; <b>Submitter:</b>&nbsp;Judy Ward&nbsp; <b>Date:</b>&nbsp;15 Dec 1998 </p>
<p>One of the operator= in the valarray helper arrays is const and one
is not. For example, look at slice_array. This operator= in Section
26.3.5.2 <a href="lib-numerics.html#lib.slice.arr.assign"> [lib.slice.arr.assign]</a> is const: </p>

<p>&nbsp;&nbsp;&nbsp; <tt>void operator=(const valarray&lt;T&gt;&amp;) const;</tt> </p>

<p>but this one in Section 26.3.5.4 <a href="lib-numerics.html#lib.slice.arr.fill"> [lib.slice.arr.fill]</a> is not: </p>

<p>&nbsp;&nbsp;&nbsp; <tt>void operator=(const T&amp;); </tt></p>

<p>The description of the semantics for these two functions is similar. </p>
<p><b>Proposed resolution:</b></p>

<p>26.3.5 <a href="lib-numerics.html#lib.template.slice.array"> [lib.template.slice.array]</a> Template class slice_array</p>
<blockquote>

   <p>In the class template definition for slice_array, replace the member
   function declaration</p>
    <pre>
      void operator=(const T&amp;);
    </pre>
   <p>with</p>
    <pre>
      void operator=(const T&amp;) const;
    </pre>
</blockquote>

<p>26.3.5.4 <a href="lib-numerics.html#lib.slice.arr.fill"> [lib.slice.arr.fill]</a> slice_array fill function</p>
<blockquote>

   <p>Change the function declaration</p>
    <pre>
      void operator=(const T&amp;);
    </pre>
   <p>to</p>
    <pre>
      void operator=(const T&amp;) const;
    </pre>
</blockquote>

<p>26.3.7 <a href="lib-numerics.html#lib.template.gslice.array"> [lib.template.gslice.array]</a> Template class gslice_array</p>
<blockquote>

   <p>In the class template definition for gslice_array, replace the member
   function declaration</p>
    <pre>
      void operator=(const T&amp;);
    </pre>
   <p>with</p>
    <pre>
      void operator=(const T&amp;) const;
    </pre>
</blockquote>

<p>26.3.7.4 <a href="lib-numerics.html#lib.gslice.array.fill"> [lib.gslice.array.fill]</a> gslice_array fill function</p>
<blockquote>

   <p>Change the function declaration</p>
    <pre>
      void operator=(const T&amp;);
    </pre>
   <p>to</p>
    <pre>
      void operator=(const T&amp;) const;
    </pre>
</blockquote>

<p>26.3.8 <a href="lib-numerics.html#lib.template.mask.array"> [lib.template.mask.array]</a> Template class mask_array</p>
<blockquote>

   <p>In the class template definition for mask_array, replace the member
   function declaration</p>
    <pre>
      void operator=(const T&amp;);
    </pre>
   <p>with</p>
    <pre>
      void operator=(const T&amp;) const;
    </pre>
</blockquote>

<p>26.3.8.4 <a href="lib-numerics.html#lib.mask.array.fill"> [lib.mask.array.fill]</a> mask_array fill function</p>
<blockquote>

   <p>Change the function declaration</p>
    <pre>
      void operator=(const T&amp;);
    </pre>
   <p>to</p>
    <pre>
      void operator=(const T&amp;) const;
    </pre>
</blockquote>

<p>26.3.9 <a href="lib-numerics.html#lib.template.indirect.array"> [lib.template.indirect.array]</a> Template class indirect_array</p>
<blockquote>

   <p>In the class template definition for indirect_array, replace the member
   function declaration</p>
    <pre>
      void operator=(const T&amp;);
    </pre>
   <p>with</p>
    <pre>
      void operator=(const T&amp;) const;
    </pre>
</blockquote>

<p>26.3.9.4 <a href="lib-numerics.html#lib.indirect.array.fill"> [lib.indirect.array.fill]</a> indirect_array fill function</p>
<blockquote>

   <p>Change the function declaration</p>
    <pre>
      void operator=(const T&amp;);
    </pre>
   <p>to</p>
    <pre>
      void operator=(const T&amp;) const;
    </pre>
</blockquote>


<p><i>[Redmond: Robert provided wording.]</i></p>

<p><b>Rationale:</b></p>
<p>There's no good reason for one version of operator= being const and
another one not.  Because of issue <a href="lwg-defects.html#253">253</a>, this now
matters: these functions are now callable in more circumstances.  In
many existing implementations, both versions are already const.</p>
<hr>
<a name="124"><h3>124.&nbsp;ctype_byname&lt;charT&gt;::do_scan_is &amp; do_scan_not return type should be const charT*</h3></a><p><b>Section:</b>&nbsp;22.2.1.2 <a href="lib-locales.html#lib.locale.ctype.byname"> [lib.locale.ctype.byname]</a>&nbsp; <b>Status:</b>&nbsp;<a href="lwg-active.html#TC">TC</a>&nbsp; <b>Submitter:</b>&nbsp;Judy Ward&nbsp; <b>Date:</b>&nbsp;15 Dec 1998</p>
<p>In Section 22.2.1.2 <a href="lib-locales.html#lib.locale.ctype.byname"> [lib.locale.ctype.byname]</a>
ctype_byname&lt;charT&gt;::do_scan_is() and do_scan_not() are declared
to return a const char* not a const charT*. </p>
<p><b>Proposed resolution:</b></p>
<p>Change Section 22.2.1.2 <a href="lib-locales.html#lib.locale.ctype.byname"> [lib.locale.ctype.byname]</a> <tt>do_scan_is()</tt> and
<tt>do_scan_not()</tt> to return a <tt> const
charT*</tt>. </p>
<hr>
<a name="125"><h3>125.&nbsp;valarray&lt;T&gt;::operator!() return type is inconsistent</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#TC">TC</a>&nbsp; <b>Submitter:</b>&nbsp;Judy Ward&nbsp; <b>Date:</b>&nbsp;15 Dec 1998</p>
<p>In Section 26.3.2 <a href="lib-numerics.html#lib.template.valarray"> [lib.template.valarray]</a> valarray&lt;T&gt;::operator!() is
declared to return a valarray&lt;T&gt;, but in Section 26.3.2.5 <a href="lib-numerics.html#lib.valarray.unary"> [lib.valarray.unary]</a> it is declared to return a valarray&lt;bool&gt;. The
latter appears to be correct. </p>
<p><b>Proposed resolution:</b></p>
<p>Change in Section 26.3.2 <a href="lib-numerics.html#lib.template.valarray"> [lib.template.valarray]</a> the declaration of
<tt>operator!()</tt> so that the return type is
<tt>valarray&lt;bool&gt;</tt>. </p>
<hr>
<a name="126"><h3>126.&nbsp;typos in Effects clause of ctype::do_narrow()</h3></a><p><b>Section:</b>&nbsp;22.2.1.1.2 <a href="lib-locales.html#lib.locale.ctype.virtuals"> [lib.locale.ctype.virtuals]</a>&nbsp; <b>Status:</b>&nbsp;<a href="lwg-active.html#TC">TC</a>&nbsp; <b>Submitter:</b>&nbsp;Judy Ward&nbsp; <b>Date:</b>&nbsp;15 Dec 1998</p>
<p>Typos in 22.2.1.1.2 need to be fixed.</p>
<p><b>Proposed resolution:</b></p>
<p>In Section 22.2.1.1.2 <a href="lib-locales.html#lib.locale.ctype.virtuals"> [lib.locale.ctype.virtuals]</a> change: </p>

<pre>   do_widen(do_narrow(c),0) == c</pre>

<p>to:</p>

<pre>   do_widen(do_narrow(c,0)) == c</pre>

<p>and change:</p>

<pre>   (is(M,c) || !ctc.is(M, do_narrow(c),dfault) )</pre>

<p>to:</p>

<pre>   (is(M,c) || !ctc.is(M, do_narrow(c,dfault)) )</pre>
<hr>
<a name="127"><h3>127.&nbsp;auto_ptr&lt;&gt; conversion issues</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#TC">TC</a>&nbsp; <b>Submitter:</b>&nbsp;Greg Colvin&nbsp; <b>Date:</b>&nbsp;17 Feb 1999</p>
<p>There are two problems with the current <tt>auto_ptr</tt> wording
in the standard: </p>

<p>First, the <tt>auto_ptr_ref</tt> definition cannot be nested
because <tt>auto_ptr&lt;Derived&gt;::auto_ptr_ref</tt> is unrelated to
<tt>auto_ptr&lt;Base&gt;::auto_ptr_ref</tt>.  <i>Also submitted by
Nathan Myers, with the same proposed resolution.</i></p>

<p>Second, there is no <tt>auto_ptr</tt> assignment operator taking an
<tt>auto_ptr_ref</tt> argument. </p>

<p>I have discussed these problems with my proposal coauthor, Bill
Gibbons, and with some compiler and library implementors, and we
believe that these problems are not desired or desirable implications
of the standard. </p>

<p>25 Aug 1999: The proposed resolution now reflects changes suggested
by Dave Abrahams, with Greg Colvin's concurrence; 1) changed
"assignment operator" to "public assignment
operator", 2) changed effects to specify use of release(), 3)
made the conversion to auto_ptr_ref const. </p>

<p>2 Feb 2000: Lisa Lippincott comments: [The resolution of] this issue
states that the conversion from auto_ptr to auto_ptr_ref should
be const.  This is not acceptable, because it would allow
initialization and assignment from _any_ const auto_ptr!  It also
introduces an implementation difficulty in writing this conversion
function -- namely, somewhere along the line, a const_cast will be
necessary to remove that const so that release() may be called.  This
may result in undefined behavior [7.1.5.1/4]. The conversion
operator does not have to be const, because a non-const implicit
object parameter may be bound to an rvalue [13.3.3.1.4/3]
[13.3.1/5]. </p>

  <p>Tokyo: The LWG removed the following from the proposed resolution:</p>

  <p>In 20.4.5 <a href="lib-utilities.html#lib.auto.ptr"> [lib.auto.ptr]</a>, paragraph 2, and 20.4.5.3 <a href="lib-utilities.html#lib.auto.ptr.conv"> [lib.auto.ptr.conv]</a>, 
  paragraph 2, make the conversion to auto_ptr_ref const:</p>
  <blockquote>
    <pre>template&lt;class Y&gt; operator auto_ptr_ref&lt;Y&gt;() const throw();</pre>
  </blockquote>
<p><b>Proposed resolution:</b></p>
<p>In 20.4.5 <a href="lib-utilities.html#lib.auto.ptr"> [lib.auto.ptr]</a>, paragraph 2, move
the <tt>auto_ptr_ref</tt> definition to namespace scope.</p>

<p>In 20.4.5 <a href="lib-utilities.html#lib.auto.ptr"> [lib.auto.ptr]</a>, paragraph 2, add
a public assignment operator to the <tt>auto_ptr</tt> definition: </p>

<blockquote>
  <pre>auto_ptr&amp; operator=(auto_ptr_ref&lt;X&gt; r) throw();</pre>
</blockquote>

<p>Also add the assignment operator to 20.4.5.3 <a href="lib-utilities.html#lib.auto.ptr.conv"> [lib.auto.ptr.conv]</a>: </p>

<blockquote>
  <pre>auto_ptr&amp; operator=(auto_ptr_ref&lt;X&gt; r) throw()</pre>

  <b>Effects:</b> Calls <tt>reset(p.release())</tt> for the <tt>auto_ptr
  p</tt> that <tt>r</tt> holds a reference to.<br>
  <b>Returns: </b><tt>*this</tt>.

</blockquote>
<hr>
<a name="129"><h3>129.&nbsp;Need error indication from seekp() and seekg()</h3></a><p><b>Section:</b>&nbsp;27.6.1.3 <a href="lib-iostreams.html#lib.istream.unformatted"> [lib.istream.unformatted]</a>, 27.6.2.4 <a href="lib-iostreams.html#lib.ostream.seeks"> [lib.ostream.seeks]</a>&nbsp; <b>Status:</b>&nbsp;<a href="lwg-active.html#TC">TC</a>&nbsp; <b>Submitter:</b>&nbsp;Angelika Langer&nbsp; <b>Date:</b>&nbsp;22 Feb 1999</p>
<p>Currently, the standard does not specify how seekg() and seekp()
indicate failure. They are not required to set failbit, and they can't
return an error indication because they must return *this, i.e. the
stream. Hence, it is undefined what happens if they fail. And they
<i>can</i> fail, for instance, when a file stream is disconnected from the
underlying file (is_open()==false) or when a wide character file
stream must perform a state-dependent code conversion, etc. </p>

<p>The stream functions seekg() and seekp() should set failbit in the
stream state in case of failure.</p>
<p><b>Proposed resolution:</b></p>
<p>Add to the Effects: clause of&nbsp; seekg() in 
27.6.1.3 <a href="lib-iostreams.html#lib.istream.unformatted"> [lib.istream.unformatted]</a> and to the Effects: clause of seekp() in
27.6.2.4 <a href="lib-iostreams.html#lib.ostream.seeks"> [lib.ostream.seeks]</a>: </p>

<blockquote>
  <p>In case of failure, the function calls <tt>setstate(failbit)</tt> (which may throw <tt>ios_base::failure</tt>).
  </p>
</blockquote>
<p><b>Rationale:</b></p>
<p>Setting failbit is the usual error reporting mechanism for streams</p>
<hr>
<a name="132"><h3>132.&nbsp;list::resize description uses random access iterators</h3></a><p><b>Section:</b>&nbsp;23.2.2.2 <a href="lib-containers.html#lib.list.capacity"> [lib.list.capacity]</a>&nbsp; <b>Status:</b>&nbsp;<a href="lwg-active.html#TC">TC</a>&nbsp; <b>Submitter:</b>&nbsp;Howard Hinnant&nbsp; <b>Date:</b>&nbsp;6 Mar 1999</p>
<p>The description reads:</p>

<p>-1- Effects:</p>

<pre>         if (sz &gt; size())
           insert(end(), sz-size(), c);
         else if (sz &lt; size())
           erase(begin()+sz, end());
         else
           ;                           //  do nothing</pre>

<p>Obviously list::resize should not be specified in terms of random access iterators.</p>
<p><b>Proposed resolution:</b></p>
<p>Change 23.2.2.2 paragraph 1 to:</p>

<p>Effects:</p>

<pre>         if (sz &gt; size())
           insert(end(), sz-size(), c);
         else if (sz &lt; size())
         {
           iterator i = begin();
           advance(i, sz);
           erase(i, end());
         }</pre>

<p><i>[Dublin: The LWG asked Howard to discuss exception safety offline
with David Abrahams. They had a discussion and believe there is
no issue of exception safety with the proposed resolution.]</i></p>
<hr>
<a name="133"><h3>133.&nbsp;map missing get_allocator()</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#TC">TC</a>&nbsp; <b>Submitter:</b>&nbsp;Howard Hinnant&nbsp; <b>Date:</b>&nbsp;6 Mar 1999</p>
<p>The title says it all.</p>
<p><b>Proposed resolution:</b></p>
<p>Insert in 23.3.1 <a href="lib-containers.html#lib.map"> [lib.map]</a>, paragraph 2,
after operator= in the map declaration:</p>

<pre>    allocator_type get_allocator() const;</pre>
<hr>
<a name="134"><h3>134.&nbsp;vector constructors over specified</h3></a><p><b>Section:</b>&nbsp;23.2.4.1 <a href="lib-containers.html#lib.vector.cons"> [lib.vector.cons]</a>&nbsp; <b>Status:</b>&nbsp;<a href="lwg-active.html#TC">TC</a>&nbsp; <b>Submitter:</b>&nbsp;Howard Hinnant&nbsp; <b>Date:</b>&nbsp;6 Mar 1999</p>
<p>The complexity description says: "It does at most 2N calls to the copy constructor
of T and logN reallocations if they are just input iterators ...".</p>

<p>This appears to be overly restrictive, dictating the precise memory/performance
tradeoff for the implementor.</p>
<p><b>Proposed resolution:</b></p>
<p>Change 23.2.4.1 <a href="lib-containers.html#lib.vector.cons"> [lib.vector.cons]</a>, paragraph 1 to:</p>

<p>-1- Complexity: The constructor template &lt;class
InputIterator&gt; vector(InputIterator first, InputIterator last)
makes only N calls to the copy constructor of T (where N is the
distance between first and last) and no reallocations if iterators
first and last are of forward, bidirectional, or random access
categories. It makes order N calls to the copy constructor of T and
order logN reallocations if they are just input iterators.
</p>
<p><b>Rationale:</b></p>
<p>"at most 2N calls" is correct only if the growth factor
is greater than or equal to 2.
</p>
<hr>
<a name="136"><h3>136.&nbsp;seekp, seekg setting wrong streams?</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#WP">WP</a>&nbsp; <b>Submitter:</b>&nbsp;Howard Hinnant&nbsp; <b>Date:</b>&nbsp;6 Mar 1999</p>
<p>I may be misunderstanding the intent, but should not seekg set only
the input stream and seekp set only the output stream? The description
seems to say that each should set both input and output streams. If
that's really the intent, I withdraw this proposal.</p>
<p><b>Proposed resolution:</b></p>
<p>In section 27.6.1.3 change:</p>

<pre>basic_istream&lt;charT,traits&gt;&amp; seekg(pos_type pos);
Effects: If fail() != true, executes rdbuf()-&gt;pubseekpos(pos). </pre>

<p>To:</p>

<pre>basic_istream&lt;charT,traits&gt;&amp; seekg(pos_type pos);
Effects: If fail() != true, executes rdbuf()-&gt;pubseekpos(pos, ios_base::in). </pre>

<p>In section 27.6.1.3 change:</p>

<pre>basic_istream&lt;charT,traits&gt;&amp; seekg(off_type&amp; off, ios_base::seekdir dir);
Effects: If fail() != true, executes rdbuf()-&gt;pubseekoff(off, dir). </pre>

<p>To:</p>

<pre>basic_istream&lt;charT,traits&gt;&amp; seekg(off_type&amp; off, ios_base::seekdir dir);
Effects: If fail() != true, executes rdbuf()-&gt;pubseekoff(off, dir, ios_base::in). </pre>

<p>In section 27.6.2.4, paragraph 2 change:</p>

<pre>-2- Effects: If fail() != true, executes rdbuf()-&gt;pubseekpos(pos). </pre>

<p>To:</p>

<pre>-2- Effects: If fail() != true, executes rdbuf()-&gt;pubseekpos(pos, ios_base::out). </pre>

<p>In section 27.6.2.4, paragraph 4 change:</p>

<pre>-4- Effects: If fail() != true, executes rdbuf()-&gt;pubseekoff(off, dir). </pre>

<p>To:</p>

<pre>-4- Effects: If fail() != true, executes rdbuf()-&gt;pubseekoff(off, dir, ios_base::out). </pre>

<p><i>[Dublin: Dietmar K&uuml;hl thinks this is probably correct, but would
like the opinion of more iostream experts before taking action.]</i></p>

<p><i>[Tokyo: Reviewed by the LWG. PJP noted that although his docs are
incorrect, his implementation already implements the Proposed
Resolution.]</i></p>

<p><i>[Post-Tokyo: Matt Austern comments:<br>
Is it a problem with basic_istream and basic_ostream, or is it a problem
with basic_stringbuf?
We could resolve the issue either by changing basic_istream and
basic_ostream, or by changing basic_stringbuf. I prefer the latter
change (or maybe both changes): I don't see any reason for the standard to
require that std::stringbuf s(std::string("foo"), std::ios_base::in);
s.pubseekoff(0, std::ios_base::beg); must fail.<br>
This requirement is a bit weird. There's no similar requirement
for basic_streambuf&lt;&gt;::seekpos, or for basic_filebuf&lt;&gt;::seekoff or
basic_filebuf&lt;&gt;::seekpos.]</i></p>
<hr>
<a name="137"><h3>137.&nbsp;Do use_facet and has_facet look in the global locale?</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#TC">TC</a>&nbsp; <b>Submitter:</b>&nbsp;Angelika Langer&nbsp; <b>Date:</b>&nbsp;17 Mar 1999</p>
<p>Section 22.1.1 <a href="lib-locales.html#lib.locale"> [lib.locale]</a> says:</p>

<p>-4- In the call to use_facet&lt;Facet&gt;(loc), the type argument
chooses a facet, making available all members of the named type. If
Facet is not present in a locale (or, failing that, in the global
locale), it throws the standard exception bad_cast. A C++ program can
check if a locale implements a particular facet with the template
function has_facet&lt;Facet&gt;(). </p>

<p>This contradicts the specification given in section 
22.1.2 <a href="lib-locales.html#lib.locale.global.templates"> [lib.locale.global.templates]</a>:
<br><br>
template &lt;class&nbsp; Facet&gt; const&nbsp; Facet&amp; use_facet(const
locale&amp;&nbsp; loc); <br>
<br>
-1- Get a reference to a facet of a locale. <br>
-2- Returns: a reference to the corresponding facet of loc, if present. <br>
-3- Throws: bad_cast if has_facet&lt;Facet&gt;(loc) is false. <br>
-4- Notes: The reference returned remains valid at least as long as any copy of loc exists
</p>
<p><b>Proposed resolution:</b></p>
<p>Remove the phrase "(or, failing that, in the global locale)"
from section 22.1.1. </p>
<p><b>Rationale:</b></p>
<p>Needed for consistency with the way locales are handled elsewhere
in the standard.</p>
<hr>
<a name="139"><h3>139.&nbsp;Optional sequence operation table description unclear</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#TC">TC</a>&nbsp; <b>Submitter:</b>&nbsp;Andrew Koenig&nbsp; <b>Date:</b>&nbsp;30 Mar 1999</p>
<p>The sentence introducing the Optional sequence operation table
(23.1.1 paragraph 12) has two problems:</p>

<p>A. It says ``The operations in table 68 are provided only for the containers for which
they take constant time.''<br>
<br>
That could be interpreted in two ways, one of them being ``Even though table 68 shows
particular operations as being provided, implementations are free to omit them if they
cannot implement them in constant time.''<br>
<br>
B. That paragraph says nothing about amortized constant time, and it should.&nbsp;</p>
<p><b>Proposed resolution:</b></p>
<p>Replace the wording in 23.1.1 paragraph 12&nbsp; which begins ``The operations in table 68 are provided only..."
with:</p>

<blockquote>
  <p>Table 68 lists sequence operations that are provided for some types of sequential
  containers but not others. An implementation shall provide these operations for all
  container types shown in the ``container'' column, and shall implement them so as to take
  amortized constant time.</p>
</blockquote>
<hr>
<a name="141"><h3>141.&nbsp;basic_string::find_last_of, find_last_not_of say pos instead of xpos</h3></a><p><b>Section:</b>&nbsp;21.3.6.4 <a href="lib-strings.html#lib.string::find.last.of"> [lib.string::find.last.of]</a>, 21.3.6.6 <a href="lib-strings.html#lib.string::find.last.not.of"> [lib.string::find.last.not.of]</a>&nbsp; <b>Status:</b>&nbsp;<a href="lwg-active.html#TC">TC</a>&nbsp; <b>Submitter:</b>&nbsp;Arch Robison&nbsp; <b>Date:</b>&nbsp;28 Apr 1999</p>
<p>Sections 21.3.6.4 paragraph 1 and 21.3.6.6 paragraph 1 surely have misprints where they
say:<br>
<br>
&#151; <tt>xpos &lt;= pos</tt> and <tt>pos &lt; size();</tt></p>

<p>Surely the document meant to say ``<tt>xpos &lt; size()</tt>'' in both places.</p>

<p><i>[Judy Ward also sent in this issue for 21.3.6.4 with the same
proposed resolution.]</i></p>
<p><b>Proposed resolution:</b></p>
<p>Change Sections 21.3.6.4 paragraph 1 and 21.3.6.6 paragraph 1, the line which says:<br>
<br>
&#151; <tt>xpos &lt;= pos</tt> and <tt>pos &lt; size();<br>
<br>
</tt>to:<br>
<tt><br>
</tt>&#151; <tt>xpos &lt;= pos</tt> and <tt>xpos &lt; size();</tt></p>
<hr>
<a name="142"><h3>142.&nbsp;lexicographical_compare complexity wrong</h3></a><p><b>Section:</b>&nbsp;25.3.8 <a href="lib-algorithms.html#lib.alg.lex.comparison"> [lib.alg.lex.comparison]</a>&nbsp; <b>Status:</b>&nbsp;<a href="lwg-active.html#TC">TC</a>&nbsp; <b>Submitter:</b>&nbsp;Howard Hinnant&nbsp; <b>Date:</b>&nbsp;20 Jun 1999</p>
<p>The lexicographical_compare complexity is specified as:<br>
<br>
&nbsp;&nbsp;&nbsp;&nbsp; "At most min((last1 - first1), (last2 - first2))
applications of the corresponding comparison."<br>
<br>
The best I can do is twice that expensive.</p>

<p>Nicolai Josuttis comments in lib-6862: You mean, to check for
equality you have to check both &lt; and &gt;? Yes, IMO you are
right! (and Matt states this complexity in his book)</p>

<p><b>Proposed resolution:</b></p>
<p>Change 25.3.8 <a href="lib-algorithms.html#lib.alg.lex.comparison"> [lib.alg.lex.comparison]</a> complexity to:</p>
    <blockquote>
    At most <tt>2*min((last1 - first1), (last2 - first2))</tt>
    applications of the corresponding comparison.
    </blockquote>

<p>Change the example at the end of paragraph 3 to read:</p>
    <blockquote>
    [Example:<br>
    <br>
    &nbsp;&nbsp;&nbsp; for ( ; first1 != last1 &amp;&amp; first2 != last2 ;
    ++first1, ++first2) {<br>
    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp; if (*first1 &lt; *first2) return true;<br>
    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp; if (*first2 &lt; *first1) return false;<br>
    &nbsp;&nbsp;&nbsp; }<br>
    &nbsp;&nbsp;&nbsp; return first1 == last1 &amp;&amp; first2 != last2;<br>
    &nbsp;&nbsp;&nbsp;<br>
    --end example]
    </blockquote>
<hr>
<a name="144"><h3>144.&nbsp;Deque constructor complexity wrong </h3></a><p><b>Section:</b>&nbsp;23.2.1.1 <a href="lib-containers.html#lib.deque.cons"> [lib.deque.cons]</a>&nbsp; <b>Status:</b>&nbsp;<a href="lwg-active.html#TC">TC</a>&nbsp; <b>Submitter:</b>&nbsp;Herb Sutter&nbsp; <b>Date:</b>&nbsp;9 May 1999</p>
<p>In 23.2.1.1 paragraph 6, the deque ctor that takes an iterator range appears
to have complexity requirements which are incorrect, and which contradict the
complexity requirements for insert(). I suspect that the text in question,
below, was taken from vector:</p>
<blockquote>
  <p>Complexity: If the iterators first and last are forward iterators,
  bidirectional iterators, or random access iterators the constructor makes only
  N calls to the copy constructor, and performs no reallocations, where N is
  last - first.</p>
</blockquote>
<p>The word "reallocations" does not really apply to deque. Further,
all of the following appears to be spurious:</p>
<blockquote>
  <p>It makes at most 2N calls to the copy constructor of T and log N
  reallocations if they are input iterators.1)</p>
  <p>1) The complexity is greater in the case of input iterators because each
  element must be added individually: it is impossible to determine the distance
  between first abd last before doing the copying.</p>
</blockquote>
<p>This makes perfect sense for vector, but not for deque. Why should deque gain
an efficiency advantage from knowing in advance the number of elements to
insert?</p>
<p><b>Proposed resolution:</b></p>
<p>In 23.2.1.1 paragraph 6, replace the Complexity description, including the
footnote, with the following text (which also corrects the "abd"
typo):</p>
<blockquote>
  <p>Complexity: Makes last - first calls to the copy constructor of T.</p>
</blockquote>
<hr>
<a name="146"><h3>146.&nbsp;complex&lt;T&gt; Inserter and Extractor need sentries</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#TC">TC</a>&nbsp; <b>Submitter:</b>&nbsp;Angelika Langer&nbsp; <b>Date:</b>&nbsp;12 May 1999</p>
<p>The <u> extractor</u> for complex numbers is specified as:&nbsp;</p>

<blockquote>

<p>     template&lt;class T, class charT, class traits&gt;&nbsp;<br>
     basic_istream&lt;charT, traits&gt;&amp;&nbsp;<br>
     operator&gt;&gt;(basic_istream&lt;charT, traits&gt;&amp;  is, complex&lt;T&gt;&amp;  x);<br>
&nbsp;<br>
Effects: Extracts a complex number x of the form: u, (u), or (u,v),
where u is the real part and v is the imaginary part
(lib.istream.formatted).&nbsp;<br>
Requires: The input values be convertible to T. If bad input is
encountered, calls is.setstate(ios::failbit) (which may throw
ios::failure (lib.iostate.flags).&nbsp;<br>
Returns: is .</p>

</blockquote>
<p>Is it intended that the extractor for complex numbers does not skip
whitespace, unlike all other extractors in the standard library do?
Shouldn't a sentry be used?&nbsp;<br>
<br>
The <u>inserter</u> for complex numbers is specified as:</p>

<blockquote>

<p>     template&lt;class T, class charT, class traits&gt;&nbsp;<br>
     basic_ostream&lt;charT, traits&gt;&amp;&nbsp;<br>
     operator&lt;&lt;(basic_ostream&lt;charT, traits&gt;&amp;  o, const complex&lt;T&gt;&amp;  x);<br>
<br>
Effects: inserts the complex number x onto the stream o as if it were implemented as follows:<br>
<br>
     template&lt;class T, class charT, class traits&gt;&nbsp;<br>
     basic_ostream&lt;charT, traits&gt;&amp;&nbsp;<br>
     operator&lt;&lt;(basic_ostream&lt;charT, traits&gt;&amp; o, const complex&lt;T&gt;&amp; x)&nbsp;<br>
     {&nbsp;<br>
             basic_ostringstream&lt;charT, traits&gt; s;&nbsp;<br>
             s.flags(o.flags());&nbsp;<br>
             s.imbue(o.getloc());&nbsp;<br>
             s.precision(o.precision());&nbsp;<br>
             s &lt;&lt; '(' &lt;&lt; x.real() &lt;&lt; "," &lt;&lt; x.imag() &lt;&lt; ')';&nbsp;<br>
             return o &lt;&lt; s.str();&nbsp;<br>
     }</p>

</blockquote>

<p>Is it intended that the inserter for complex numbers ignores the
field width and does not do any padding? If, with the suggested
implementation above, the field width were set in the stream then the
opening parentheses would be adjusted, but the rest not, because the
field width is reset to zero after each insertion.</p>

<p>I think that both operations should use sentries, for sake of
consistency with the other inserters and extractors in the
library. Regarding the issue of padding in the inserter, I don't know
what the intent was.&nbsp;</p>
<p><b>Proposed resolution:</b></p>
<p>After 26.2.6 <a href="lib-numerics.html#lib.complex.ops"> [lib.complex.ops]</a> paragraph 14 (operator&gt;&gt;), add a
Notes clause:</p>

<blockquote>

<p>Notes: This extraction is performed as a series of simpler
extractions. Therefore, the skipping of whitespace is specified to be the
same for each of the simpler extractions.</p>

</blockquote>
<p><b>Rationale:</b></p>
<p>For extractors, the note is added to make it clear that skipping whitespace
follows an "all-or-none" rule.</p>

<p>For inserters, the LWG believes there is no defect; the standard is correct
as written.</p>
<hr>
<a name="147"><h3>147.&nbsp;Library Intro refers to global functions that aren't global</h3></a><p><b>Section:</b>&nbsp;17.4.4.3 <a href="lib-intro.html#lib.global.functions"> [lib.global.functions]</a>&nbsp; <b>Status:</b>&nbsp;<a href="lwg-active.html#TC">TC</a>&nbsp; <b>Submitter:</b>&nbsp;Lois Goldthwaite&nbsp; <b>Date:</b>&nbsp;4 Jun 1999</p>
<p>The library had many global functions until 17.4.1.1 [lib.contents]
paragraph 2 was added: </p>

<blockquote>

<p>All library entities except macros, operator new and operator
delete are defined within the namespace std or namespaces nested
within namespace std. </p>

</blockquote>

<p>It appears "global function" was never updated in the following: </p>

<blockquote>

<p>17.4.4.3 - Global functions [lib.global.functions]<br>
<br>
-1- It is unspecified whether any global functions in the C++ Standard
Library are defined as inline (dcl.fct.spec).<br>
<br>
-2- A call to a global function signature described in Clauses
lib.language.support through lib.input.output behaves the same as if
the implementation declares no additional global function
signatures.*<br>
<br>
    [Footnote: A valid C++ program always calls the expected library
    global function. An implementation may also define additional
    global functions that would otherwise not be called by a valid C++
    program. --- end footnote]<br>
<br>
-3- A global function cannot be declared by the implementation as
taking additional default arguments.&nbsp;<br>
<br>
17.4.4.4 - Member functions [lib.member.functions]<br>
<br>
-2- An implementation can declare additional non-virtual member
function signatures within a class: </p>

  <blockquote>

<p>-- by adding arguments with default values to a member function
signature; The same latitude does not extend to the implementation of
virtual or global functions, however. </p>

  </blockquote>
</blockquote>
<p><b>Proposed resolution:</b></p>
<p>     Change "global" to "global or non-member" in:</p>
<blockquote>
  <p>17.4.4.3 [lib.global.functions] section title,<br>
  17.4.4.3 [lib.global.functions] para 1,<br>
  17.4.4.3 [lib.global.functions] para 2 in 2 places plus 2 
           places in the footnote,<br>
  17.4.4.3 [lib.global.functions] para 3,<br>
  17.4.4.4 [lib.member.functions] para 2</p>
</blockquote>
<p><b>Rationale:</b></p>
<p>
Because operator new and delete are global, the proposed resolution
was changed from "non-member" to "global or non-member.
</p>
<hr>
<a name="148"><h3>148.&nbsp;Functions in the example facet BoolNames should be const</h3></a><p><b>Section:</b>&nbsp;22.2.8 <a href="lib-locales.html#lib.facets.examples"> [lib.facets.examples]</a>&nbsp; <b>Status:</b>&nbsp;<a href="lwg-active.html#TC">TC</a>&nbsp; <b>Submitter:</b>&nbsp;Jeremy Siek&nbsp; <b>Date:</b>&nbsp;3 Jun 1999</p>
<p>In 22.2.8 <a href="lib-locales.html#lib.facets.examples"> [lib.facets.examples]</a> paragraph 13, the do_truename() and
do_falsename() functions in the example facet BoolNames should be
const. The functions they are overriding in
numpunct_byname&lt;char&gt; are const. </p>
<p><b>Proposed resolution:</b></p>
<p>In 22.2.8 <a href="lib-locales.html#lib.facets.examples"> [lib.facets.examples]</a> paragraph 13, insert "const" in
two places:</p>
<blockquote>
  <p><tt>string do_truename() const { return "Oui Oui!"; }<br>
  string do_falsename() const { return "Mais Non!"; }</tt></p>
</blockquote>
<hr>
<a name="150"><h3>150.&nbsp;Find_first_of says integer instead of iterator </h3></a><p><b>Section:</b>&nbsp;25.1.4 <a href="lib-algorithms.html#lib.alg.find.first.of"> [lib.alg.find.first.of]</a>&nbsp; <b>Status:</b>&nbsp;<a href="lwg-active.html#TC">TC</a>&nbsp; <b>Submitter:</b>&nbsp;Matt McClure&nbsp; <b>Date:</b>&nbsp;30 Jun 1999</p>
<p><b>Proposed resolution:</b></p>
<p>Change 25.1.4 <a href="lib-algorithms.html#lib.alg.find.first.of"> [lib.alg.find.first.of]</a> paragraph 2 from:</p>

<blockquote>
<p>Returns: The first iterator i in the range [first1, last1) such
that for some <u>integer</u> j in the range [first2, last2) ...</p>
</blockquote>

<p>to:</p>

<blockquote>
<p>Returns: The first iterator i in the range [first1, last1) such
that for some iterator j in the range [first2, last2) ...</p>
</blockquote>
<hr>
<a name="151"><h3>151.&nbsp;Can't currently clear() empty container</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#TC">TC</a>&nbsp; <b>Submitter:</b>&nbsp;Ed Brey&nbsp; <b>Date:</b>&nbsp;21 Jun 1999</p>
<p>For both sequences and associative containers, a.clear() has the
semantics of erase(a.begin(),a.end()), which is undefined for an empty
container since erase(q1,q2) requires that q1 be dereferenceable
(23.1.1,3 and 23.1.2,7).  When the container is empty, a.begin() is
not dereferenceable.<br>
<br>
The requirement that q1 be unconditionally dereferenceable causes many
operations to be intuitively undefined, of which clearing an empty
container is probably the most dire.<br>
<br>
Since q1 and q2 are only referenced in the range [q1, q2), and [q1,
q2) is required to be a valid range, stating that q1 and q2 must be
iterators or certain kinds of iterators is unnecessary.
</p>
<p><b>Proposed resolution:</b></p>
<p>In 23.1.1, paragraph 3, change:</p>
<blockquote>
  <p>p and q2 denote valid iterators to a, q <u> and q1</u> denote valid dereferenceable iterators to a, [q1, q2) denotes a valid range</p>
</blockquote>
<p>to:</p>
<blockquote>
  <p>p denotes a valid iterator to a, q denotes a valid dereferenceable iterator to a, [q1, q2) denotes a valid range<u>
  in a</u></p>
</blockquote>
<p>In 23.1.2, paragraph 7, change:</p>
<blockquote>
  <p>p and q2 are valid iterators to a, q <u> and q1</u> are valid dereferenceable
  iterators to a, [q1, q2) is a valid range</p>
</blockquote>
<p>to</p>
<blockquote>
  <p>p is a valid iterator to a, q is a valid dereferenceable iterator to a, [q1, q2) is a valid range
  <u>into a</u></p>
</blockquote>
<hr>
<a name="152"><h3>152.&nbsp;Typo in <tt>scan_is()</tt> semantics</h3></a><p><b>Section:</b>&nbsp;22.2.1.1.2 <a href="lib-locales.html#lib.locale.ctype.virtuals"> [lib.locale.ctype.virtuals]</a>&nbsp; <b>Status:</b>&nbsp;<a href="lwg-active.html#TC">TC</a>&nbsp; <b>Submitter:</b>&nbsp;Dietmar K&uuml;hl&nbsp; <b>Date:</b>&nbsp;20 Jul 1999</p>
<p>The semantics of <tt>scan_is()</tt> (paragraphs 4 and 6) is not exactly described
because there is no function <tt>is()</tt> which only takes a character as
argument. Also, in the effects clause (paragraph 3), the semantic is also kept
vague.</p>
<p><b>Proposed resolution:</b></p>
<p>In 22.2.1.1.2 <a href="lib-locales.html#lib.locale.ctype.virtuals"> [lib.locale.ctype.virtuals]</a> paragraphs 4 and 6, change the returns
clause from:</p>
<blockquote>
  <p>"... such that <tt>is(*p)</tt>
would..."</p>
</blockquote>
<p>to:&nbsp; "... such that <tt>is(m, *p)</tt>
 would...."</p>
<hr>
<a name="153"><h3>153.&nbsp;Typo in <tt>narrow()</tt> semantics</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#WP">WP</a>&nbsp; <b>Submitter:</b>&nbsp;Dietmar K&uuml;hl&nbsp; <b>Date:</b>&nbsp;20 Jul 1999</p>
<p>The description of the array version of <tt>narrow()</tt> (in
paragraph 11) is flawed: There is no member <tt>do_narrow()</tt> which
takes only three arguments because in addition to the range a default
character is needed.</p>

<p>Additionally, for both <tt>widen</tt> and <tt>narrow</tt> we have
two signatures followed by a <b>Returns</b> clause that only addresses
one of them.</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 22.2.1.3.2 <a href="lib-locales.html#lib.facet.ctype.char.members"> [lib.facet.ctype.char.members]</a> paragraph 10 and 11 from:</p>
<pre>        char        narrow(char c, char /*dfault*/) const;
        const char* narrow(const char* low, const char* high,
                           char /*dfault*/, char* to) const;</pre>
<pre>        Returns: do_narrow(low, high, to).</pre>
<p>to:</p>
<pre>        char        narrow(char c, char dfault) const;
        const char* narrow(const char* low, const char* high,
                           char dfault, char* to) const;</pre>
<pre>        Returns: do_narrow(c, dfault) or
                 do_narrow(low, high, dfault, to), respectively.</pre>

<p><i>[Kona: 1) the problem occurs in additional places, 2) a user
defined version could be different.]</i></p>

<p><i>[Post-Tokyo: Dietmar provided the above wording at the request of
the LWG. He could find no other places the problem occurred. He
asks for clarification of the Kona "a user defined
version..." comment above.  Perhaps it was a circuitous way of
saying "dfault" needed to be uncommented?]</i></p>

<p><i>[Post-Toronto: the issues list maintainer has merged in the
proposed resolution from issue <a href="lwg-closed.html#207">207</a>, which addresses the
same paragraphs.]</i></p>
<hr>
<a name="154"><h3>154.&nbsp;Missing <tt>double</tt> specifier for <tt>do_get()</tt>
</h3></a><p><b>Section:</b>&nbsp;22.2.2.1.2 <a href="lib-locales.html#lib.facet.num.get.virtuals"> [lib.facet.num.get.virtuals]</a>&nbsp; <b>Status:</b>&nbsp;<a href="lwg-active.html#TC">TC</a>&nbsp; <b>Submitter:</b>&nbsp;Dietmar K&uuml;hl&nbsp; <b>Date:</b>&nbsp;20 Jul 1999</p>
<p>The table in paragraph 7 for the length modifier does not list the length
modifier <tt>l</tt> to be applied if the type is <tt>double</tt>. Thus, the
standard asks the implementation to do undefined things when using <tt>scanf()</tt>
(the missing length modifier for <tt>scanf()</tt> when scanning <tt>double</tt>s
is actually a problem I found quite often in production code, too).</p>
<p><b>Proposed resolution:</b></p>
<p>In 22.2.2.1.2 <a href="lib-locales.html#lib.facet.num.get.virtuals"> [lib.facet.num.get.virtuals]</a>, paragraph 7, add a row in the Length
Modifier table to say that for <tt>double</tt> a length modifier
<tt>l</tt> is to be used.</p>
<p><b>Rationale:</b></p>
<p>The standard makes an embarrassing beginner's mistake.</p>
<hr>
<a name="155"><h3>155.&nbsp;Typo in naming the class defining the class <tt>Init</tt>
</h3></a><p><b>Section:</b>&nbsp;27.3 <a href="lib-iostreams.html#lib.iostream.objects"> [lib.iostream.objects]</a>&nbsp; <b>Status:</b>&nbsp;<a href="lwg-active.html#TC">TC</a>&nbsp; <b>Submitter:</b>&nbsp;Dietmar K&uuml;hl&nbsp; <b>Date:</b>&nbsp;20 Jul 1999</p>
<p>There are conflicting statements about where the class
<tt>Init</tt> is defined. According to 27.3 <a href="lib-iostreams.html#lib.iostream.objects"> [lib.iostream.objects]</a> paragraph 2
it is defined as <tt>basic_ios::Init</tt>, according to 27.4.2 <a href="lib-iostreams.html#lib.ios.base"> [lib.ios.base]</a> it is defined as <tt>ios_base::Init</tt>.</p>
<p><b>Proposed resolution:</b></p>
<p>Change 27.3 <a href="lib-iostreams.html#lib.iostream.objects"> [lib.iostream.objects]</a> paragraph 2 from
"<tt>basic_ios::Init"</tt> to
"<tt>ios_base::Init"</tt>.</p>
<p><b>Rationale:</b></p>
<p>Although not strictly wrong, the standard was misleading enough to warrant
the change.</p>
<hr>
<a name="156"><h3>156.&nbsp;Typo in <tt>imbue()</tt> description</h3></a><p><b>Section:</b>&nbsp;27.4.2.3 <a href="lib-iostreams.html#lib.ios.base.locales"> [lib.ios.base.locales]</a>&nbsp; <b>Status:</b>&nbsp;<a href="lwg-active.html#TC">TC</a>&nbsp; <b>Submitter:</b>&nbsp;Dietmar K&uuml;hl&nbsp; <b>Date:</b>&nbsp;20 Jul 1999</p>
<p>There is a small discrepancy between the declarations of
<tt>imbue()</tt>: in 27.4.2 <a href="lib-iostreams.html#lib.ios.base"> [lib.ios.base]</a> the argument is passed as
<tt>locale const&amp;</tt> (correct), in 27.4.2.3 <a href="lib-iostreams.html#lib.ios.base.locales"> [lib.ios.base.locales]</a> it
is passed as <tt>locale const</tt> (wrong).</p>
<p><b>Proposed resolution:</b></p>
<p>In 27.4.2.3 <a href="lib-iostreams.html#lib.ios.base.locales"> [lib.ios.base.locales]</a> change the <tt>imbue</tt> argument
from "<tt>locale const" to "locale
const&amp;".</tt></p>
<hr>
<a name="158"><h3>158.&nbsp;Underspecified semantics for <tt>setbuf()</tt>
</h3></a><p><b>Section:</b>&nbsp;27.5.2.4.2 <a href="lib-iostreams.html#lib.streambuf.virt.buffer"> [lib.streambuf.virt.buffer]</a>&nbsp; <b>Status:</b>&nbsp;<a href="lwg-active.html#TC">TC</a>&nbsp; <b>Submitter:</b>&nbsp;Dietmar K&uuml;hl&nbsp; <b>Date:</b>&nbsp;20 Jul 1999</p>
<p>The default behavior of <tt>setbuf()</tt> is described only for the
situation that <tt>gptr() != 0 &amp;&amp; gptr() != egptr()</tt>:
namely to do nothing.  What has to be done in other situations&nbsp;
is not described although there is actually only one reasonable
approach, namely to do nothing, too.</p> 

<p>Since changing the buffer would almost certainly mess up most
buffer management of derived classes unless these classes do it
themselves, the default behavior of <tt>setbuf()</tt> should always be
to do nothing.</p>
<p><b>Proposed resolution:</b></p>
<p>Change 27.5.2.4.2 <a href="lib-iostreams.html#lib.streambuf.virt.buffer"> [lib.streambuf.virt.buffer]</a>, paragraph 3, Default behavior,
to: "Default behavior: Does nothing. Returns this."</p>
<hr>
<a name="159"><h3>159.&nbsp;Strange use of <tt>underflow()</tt>
</h3></a><p><b>Section:</b>&nbsp;27.5.2.4.3 <a href="lib-iostreams.html#lib.streambuf.virt.get"> [lib.streambuf.virt.get]</a>&nbsp; <b>Status:</b>&nbsp;<a href="lwg-active.html#TC">TC</a>&nbsp; <b>Submitter:</b>&nbsp;Dietmar K&uuml;hl&nbsp; <b>Date:</b>&nbsp;20 Jul 1999</p>
<p>The description of the meaning of the result of
<tt>showmanyc()</tt> seems to be rather strange: It uses calls to
<tt>underflow()</tt>. Using <tt>underflow()</tt> is strange because
this function only reads the current character but does not extract
it, <tt>uflow()</tt> would extract the current character. This should
be fixed to use <tt>sbumpc()</tt> instead.</p>
<p><b>Proposed resolution:</b></p>
<p>Change 27.5.2.4.3 <a href="lib-iostreams.html#lib.streambuf.virt.get"> [lib.streambuf.virt.get]</a> paragraph 1,
<tt>showmanyc()</tt>returns clause, by replacing the word
"supplied" with the words "extracted from the
stream".</p>
<hr>
<a name="160"><h3>160.&nbsp;Typo: Use of non-existing function <tt>exception()</tt>
</h3></a><p><b>Section:</b>&nbsp;27.6.1.1 <a href="lib-iostreams.html#lib.istream"> [lib.istream]</a>&nbsp; <b>Status:</b>&nbsp;<a href="lwg-active.html#TC">TC</a>&nbsp; <b>Submitter:</b>&nbsp;Dietmar K&uuml;hl&nbsp; <b>Date:</b>&nbsp;20 Jul 1999</p>
<p>The paragraph 4 refers to the function <tt>exception()</tt> which
is not defined. Probably, the referred function is
<tt>basic_ios&lt;&gt;::exceptions()</tt>.</p>
<p><b>Proposed resolution:</b></p>
<p>In 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>, paragraph 1,
27.6.2.1 <a href="lib-iostreams.html#lib.ostream"> [lib.ostream]</a>, paragraph 3, and 27.6.2.5.1 <a href="lib-iostreams.html#lib.ostream.formatted.reqmts"> [lib.ostream.formatted.reqmts]</a>,
paragraph 1, change "<tt>exception()" to
"exceptions()"</tt>.</p>

<p><i>[Note to Editor: "exceptions" with an "s"
is the correct spelling.]</i></p>
<hr>
<a name="161"><h3>161.&nbsp;Typo: <tt>istream_iterator</tt> vs. <tt>istreambuf_iterator</tt>
</h3></a><p><b>Section:</b>&nbsp;27.6.1.2.2 <a href="lib-iostreams.html#lib.istream.formatted.arithmetic"> [lib.istream.formatted.arithmetic]</a>&nbsp; <b>Status:</b>&nbsp;<a href="lwg-active.html#TC">TC</a>&nbsp; <b>Submitter:</b>&nbsp;Dietmar K&uuml;hl&nbsp; <b>Date:</b>&nbsp;20 Jul 1999</p>
<p>The note in the second paragraph pretends that the first argument
is an object of type <tt>istream_iterator</tt>. This is wrong: It is
an object of type <tt>istreambuf_iterator</tt>.</p>
<p><b>Proposed resolution:</b></p>
<p>Change 27.6.1.2.2 <a href="lib-iostreams.html#lib.istream.formatted.arithmetic"> [lib.istream.formatted.arithmetic]</a> from:</p>
<blockquote>
  <p>The first argument provides an object of the istream_iterator class...</p>
</blockquote>
<p>to</p>
<blockquote>
  <p>The first argument provides an object of the istreambuf_iterator class...</p>
</blockquote>
<hr>
<a name="164"><h3>164.&nbsp;do_put() has apparently unused fill argument</h3></a><p><b>Section:</b>&nbsp;22.2.5.3.2 <a href="lib-locales.html#lib.locale.time.put.virtuals"> [lib.locale.time.put.virtuals]</a>&nbsp; <b>Status:</b>&nbsp;<a href="lwg-active.html#TC">TC</a>&nbsp; <b>Submitter:</b>&nbsp;Angelika Langer&nbsp; <b>Date:</b>&nbsp;23 Jul 1999</p>
<p>In 22.2.5.3.2 <a href="lib-locales.html#lib.locale.time.put.virtuals"> [lib.locale.time.put.virtuals]</a> the do_put() function is specified
as taking a fill character as an argument, but the description of the
function does not say whether the character is used at all and, if so,
in which way. The same holds for any format control parameters that
are accessible through the ios_base&amp; argument, such as the
adjustment or the field width. Is strftime() supposed to use the fill
character in any way? In any case, the specification of
time_put.do_put() looks inconsistent to me.<br> <br> Is the
signature of do_put() wrong, or is the effects clause incomplete?</p>
<p><b>Proposed resolution:</b></p>
<p>Add the following note after 22.2.5.3.2 <a href="lib-locales.html#lib.locale.time.put.virtuals"> [lib.locale.time.put.virtuals]</a>
paragraph 2:</p>
<blockquote>
  <p>  [Note: the <tt>fill</tt> argument may be used in the implementation-defined  formats, or by derivations.  A space character is a reasonable default
  for this argument. --end Note]</p>
</blockquote>
<p><b>Rationale:</b></p>
<p>The LWG felt that while the normative text was correct,
users need some guidance on what to pass for the <tt>fill</tt>
argument since the standard doesn't say how it's used.</p>
<hr>
<a name="165"><h3>165.&nbsp;<tt>xsputn()</tt>, <tt>pubsync()</tt> never called by <tt>basic_ostream</tt> members?</h3></a><p><b>Section:</b>&nbsp;27.6.2.1 <a href="lib-iostreams.html#lib.ostream"> [lib.ostream]</a>&nbsp; <b>Status:</b>&nbsp;<a href="lwg-active.html#WP">WP</a>&nbsp; <b>Submitter:</b>&nbsp;Dietmar K&uuml;hl&nbsp; <b>Date:</b>&nbsp;20 Jul 1999</p>
<p>Paragraph 2 explicitly states that none of the <tt>basic_ostream</tt>
functions falling into one of the groups "formatted output functions"
and "unformatted output functions" calls any stream buffer function
which might call a virtual function other than <tt>overflow()</tt>. Basically
this is fine but this implies that <tt>sputn()</tt> (this function would call
the virtual function <tt>xsputn()</tt>) is never called by any of the standard
output functions. Is this really intended? At minimum it would be convenient to
call <tt>xsputn()</tt> for strings... Also, the statement that <tt>overflow()</tt>
is the only virtual member of <tt>basic_streambuf</tt> called is in conflict
with the definition of <tt>flush()</tt> which calls <tt>rdbuf()-&gt;pubsync()</tt>
and thereby the virtual function <tt>sync()</tt> (<tt>flush()</tt> is listed
under "unformatted output functions").</p>
<p>In addition, I guess that the sentence starting with "They may use other
public members of <tt>basic_ostream</tt> ..." probably was intended to
start with "They may use other public members of <tt>basic_streamuf</tt>..."
although the problem with the virtual members exists in both cases.</p>
<p>I see two obvious resolutions:</p>
<ol>
  <li>state in a footnote that this means that <tt>xsputn()</tt> will never be
    called by any ostream member and that this is intended.</li>
  <li>relax the restriction and allow calling <tt>overflow()</tt> and <tt>xsputn()</tt>.
    Of course, the problem with <tt>flush()</tt> has to be resolved in some way.</li>
</ol>
<p><b>Proposed resolution:</b></p>
<p>Change the last sentence of 27.6.2.1 (lib.ostream) paragraph 2 from:</p>
<blockquote>
  <p>They may use other public members of basic_ostream except that they do not
  invoke any virtual members of rdbuf() except overflow().</p>
</blockquote>
<p>to:</p>
<blockquote>
  <p>They may use other public members of basic_ostream except that they shall
  not invoke any virtual members of rdbuf() except overflow(), xsputn(), and
  sync().</p>
</blockquote>

<p><i>[Kona: the LWG believes this is a problem. Wish to ask Jerry or
PJP why the standard is written this way.]</i></p>

<p><i>[Post-Tokyo: Dietmar supplied wording at the request of the
LWG. He comments: The rules can be made a little bit more specific if
necessary be explicitly spelling out what virtuals are allowed to be
called from what functions and eg to state specifically that flush()
is allowed to call sync() while other functions are not.]</i></p>
<hr>
<a name="167"><h3>167.&nbsp;Improper use of <tt>traits_type::length()</tt>
</h3></a><p><b>Section:</b>&nbsp;27.6.2.5.4 <a href="lib-iostreams.html#lib.ostream.inserters.character"> [lib.ostream.inserters.character]</a>&nbsp; <b>Status:</b>&nbsp;<a href="lwg-active.html#WP">WP</a>&nbsp; <b>Submitter:</b>&nbsp;Dietmar K&uuml;hl&nbsp; <b>Date:</b>&nbsp;20 Jul 1999</p>
<p>Paragraph 4 states that the length is determined using
<tt>traits::length(s)</tt>.  Unfortunately, this function is not
defined for example if the character type is <tt>wchar_t</tt> and the
type of <tt>s</tt> is <tt>char const*</tt>. Similar problems exist if
the character type is <tt>char</tt> and the type of <tt>s</tt> is
either <tt>signed char const*</tt> or <tt>unsigned char
const*</tt>.</p>
<p><b>Proposed resolution:</b></p>
<p>Change 27.6.2.5.4 <a href="lib-iostreams.html#lib.ostream.inserters.character"> [lib.ostream.inserters.character]</a> paragraph 4 from:</p>
<blockquote>
  <p>Effects: Behaves like an formatted inserter (as described in
  lib.ostream.formatted.reqmts) of out. After a sentry object is
  constructed it inserts characters. The number of characters starting
  at s to be inserted is traits::length(s). Padding is determined as
  described in lib.facet.num.put.virtuals. The traits::length(s)
  characters starting at s are widened using out.widen
  (lib.basic.ios.members). The widened characters and any required
  padding are inserted into out. Calls width(0).</p>
</blockquote>
<p>to:</p>
<blockquote>
  <p>Effects: Behaves like a formatted inserter (as described in
  lib.ostream.formatted.reqmts) of out. After a sentry object is
  constructed it inserts <i>n</i> characters starting at <i>s</i>,
  where <i>n</i> is the number that would be computed as if by:</p>
  <ul>
  <li>traits::length(s) for the overload where the first argument is of
    type basic_ostream&lt;charT, traits&gt;&amp; and the second is
    of type const charT*, and also for the overload where the first
    argument is of type basic_ostream&lt;char, traits&gt;&amp; and
    the second is of type const char*.</li>
  <li>std::char_traits&lt;char&gt;::length(s) 
    for the overload where the first argument is of type 
    basic_ostream&lt;charT, traits&gt;&amp; and the second is of type
    const char*.</li>
  <li>traits::length(reinterpret_cast&lt;const char*&gt;(s)) 
    for the other two overloads.</li>
  </ul>
  <p>Padding is determined as described in
  lib.facet.num.put.virtuals. The <i>n</i> characters starting at
  <i>s</i> are widened using out.widen (lib.basic.ios.members).  The
  widened characters and any required padding are inserted into
  out. Calls width(0).</p>
</blockquote>

<p><i>[Santa Cruz: Matt supplied new wording]</i></p>

<p><i>[Kona: changed "where <i>n</i> is" to " where <i>n</i> is the
  number that would be computed as if by"]</i></p> 

<p><b>Rationale:</b></p>
<p>We have five separate cases.  In two of them we can use the
user-supplied traits class without any fuss.  In the other three we
try to use something as close to that user-supplied class as possible.
In two cases we've got a traits class that's appropriate for
char and what we've got is a const signed char* or a const
unsigned char*; that's close enough so we can just use a reinterpret
cast, and continue to use the user-supplied traits class.  Finally,
there's one case where we just have to give up: where we've got a
traits class for some arbitrary charT type, and we somehow have to
deal with a const char*.  There's nothing better to do but fall back
to char_traits&lt;char&gt;</p>
<hr>
<a name="168"><h3>168.&nbsp;Typo: formatted vs. unformatted</h3></a><p><b>Section:</b>&nbsp;27.6.2.6 <a href="lib-iostreams.html#lib.ostream.unformatted"> [lib.ostream.unformatted]</a>&nbsp; <b>Status:</b>&nbsp;<a href="lwg-active.html#TC">TC</a>&nbsp; <b>Submitter:</b>&nbsp;Dietmar K&uuml;hl&nbsp; <b>Date:</b>&nbsp;20 Jul 1999</p>
<p>The first paragraph begins with a descriptions what has to be done
in <i>formatted</i> output functions. Probably this is a typo and the
paragraph really want to describe unformatted output functions...</p>
<p><b>Proposed resolution:</b></p>
<p>In 27.6.2.6 <a href="lib-iostreams.html#lib.ostream.unformatted"> [lib.ostream.unformatted]</a> paragraph 1, the first and last
sentences, change the word "formatted" to
"unformatted":</p>
<blockquote>
  <p>"Each <b>unformatted </b> output function begins ..."<br>
  "... value specified for the <b>unformatted </b>  output 
  function."</p>
</blockquote>
<hr>
<a name="169"><h3>169.&nbsp;Bad efficiency of <tt>overflow()</tt> mandated</h3></a><p><b>Section:</b>&nbsp;27.7.1.3 <a href="lib-iostreams.html#lib.stringbuf.virtuals"> [lib.stringbuf.virtuals]</a>&nbsp; <b>Status:</b>&nbsp;<a href="lwg-active.html#TC">TC</a>&nbsp; <b>Submitter:</b>&nbsp;Dietmar K&uuml;hl&nbsp; <b>Date:</b>&nbsp;20 Jul 1999</p>
<p>Paragraph 8, Notes, of this section seems to mandate an extremely
inefficient way of buffer handling for <tt>basic_stringbuf</tt>,
especially in view of the restriction that <tt>basic_ostream</tt>
member functions are not allowed to use <tt>xsputn()</tt> (see 27.6.2.1 <a href="lib-iostreams.html#lib.ostream"> [lib.ostream]</a>): For each character to be inserted, a new buffer
is to be created.</p> 
<p>Of course, the resolution below requires some handling of
simultaneous input and output since it is no longer possible to update
<tt>egptr()</tt> whenever <tt>epptr()</tt> is changed. A possible
solution is to handle this in <tt>underflow()</tt>.</p>
<p><b>Proposed resolution:</b></p>
<p>In 27.7.1.3 <a href="lib-iostreams.html#lib.stringbuf.virtuals"> [lib.stringbuf.virtuals]</a> paragraph 8, Notes, insert the words
"at least" as in the following:</p>
<blockquote>
  <p>To make a write position available, the function reallocates (or initially
  allocates) an array object with a sufficient number of elements to hold the
  current array object (if any), plus <b>at least</b> one additional write
  position.</p>
</blockquote>
<hr>
<a name="170"><h3>170.&nbsp;Inconsistent definition of <tt>traits_type</tt>
</h3></a><p><b>Section:</b>&nbsp;27.7.4 <a href="lib-iostreams.html#lib.stringstream"> [lib.stringstream]</a>&nbsp; <b>Status:</b>&nbsp;<a href="lwg-active.html#TC">TC</a>&nbsp; <b>Submitter:</b>&nbsp;Dietmar K&uuml;hl&nbsp; <b>Date:</b>&nbsp;20 Jul 1999</p>
<p>The classes <tt>basic_stringstream</tt> (27.7.4 <a href="lib-iostreams.html#lib.stringstream"> [lib.stringstream]</a>),
<tt>basic_istringstream</tt> (27.7.2 <a href="lib-iostreams.html#lib.istringstream"> [lib.istringstream]</a>), and
<tt>basic_ostringstream</tt> (27.7.3 <a href="lib-iostreams.html#lib.ostringstream"> [lib.ostringstream]</a>) are inconsistent
in their definition of the type <tt>traits_type</tt>: For
<tt>istringstream</tt>, this type is defined, for the other two it is
not. This should be consistent.</p>
<p><b>Proposed resolution:</b></p>
<p><b>Proposed resolution:</b></p> <p>To the declarations of
<tt>basic_ostringstream</tt> (27.7.3 <a href="lib-iostreams.html#lib.ostringstream"> [lib.ostringstream]</a>) and
<tt>basic_stringstream</tt> (27.7.4 <a href="lib-iostreams.html#lib.stringstream"> [lib.stringstream]</a>) add:</p>
<blockquote>
<pre>typedef traits traits_type;</pre>
</blockquote>
<hr>
<a name="171"><h3>171.&nbsp;Strange <tt>seekpos()</tt> semantics due to joint position</h3></a><p><b>Section:</b>&nbsp;27.8.1.4 <a href="lib-iostreams.html#lib.filebuf.virtuals"> [lib.filebuf.virtuals]</a>&nbsp; <b>Status:</b>&nbsp;<a href="lwg-active.html#WP">WP</a>&nbsp; <b>Submitter:</b>&nbsp;Dietmar K&uuml;hl&nbsp; <b>Date:</b>&nbsp;20 Jul 1999</p>
<p>Overridden virtual functions, seekpos()</p> <p>In 27.8.1.1 <a href="lib-iostreams.html#lib.filebuf"> [lib.filebuf]</a> paragraph 3, it is stated that a joint input and
output position is maintained by <tt>basic_filebuf</tt>. Still, the
description of <tt>seekpos()</tt> seems to talk about different file
positions. In particular, it is unclear (at least to me) what is
supposed to happen to the output buffer (if there is one) if only the
input position is changed. The standard seems to mandate that the
output buffer is kept and processed as if there was no positioning of
the output position (by changing the input position). Of course, this
can be exactly what you want if the flag <tt>ios_base::ate</tt> is
set. However, I think, the standard should say something like
this:</p>
<ul>
  <li>If <tt>(which &amp; mode) == 0</tt> neither read nor write position is
    changed and the call fails. Otherwise, the joint read and write position is
    altered to correspond to <tt>sp</tt>.</li>
  <li>If there is an output buffer, the output sequences is updated and any
    unshift sequence is written before the position is altered.</li>
  <li>If there is an input buffer, the input sequence is updated after the
    position is altered.</li>
</ul>
<p>Plus the appropriate error handling, that is...</p>
<p><b>Proposed resolution:</b></p>
<p>Change the unnumbered paragraph in 27.8.1.4 (lib.filebuf.virtuals) before
paragraph 14 from:</p>
<blockquote>
  <p>pos_type seekpos(pos_type sp, ios_base::openmode = ios_base::in |
  ios_base::out);</p>
  <p>Alters the file position, if possible, to correspond to the position stored
  in sp (as described below).</p>
  <p>- if (which&amp;ios_base::in)!=0, set the file position to sp, then update
  the input sequence</p>
  <p>- if (which&amp;ios_base::out)!=0, then update the output sequence, write
  any unshift sequence, and set the file position to sp.</p>
</blockquote>
<p>to:</p>
<blockquote>
  <p>pos_type seekpos(pos_type sp, ios_base::openmode = ios_base::in |
  ios_base::out);</p>
  <p>Alters the file position, if possible, to correspond to the position stored
  in sp (as described below). Altering the file position performs as follows:</p>
  <p>1. if (om &amp; ios_base::out)!=0, then update the output sequence and
  write any unshift sequence;</p>
  <p>2. set the file position to sp;</p>
  <p>3. if (om &amp; ios_base::in)!=0, then update the input sequence;</p>
  <p>where om is the open mode passed to the last call to open(). The operation
  fails if is_open() returns false.</p>
</blockquote>

<p><i>[Kona: Dietmar is working on a proposed resolution.]</i></p>
<p><i>[Post-Tokyo: Dietmar supplied the above wording.]</i></p>
<hr>
<a name="172"><h3>172.&nbsp;Inconsistent types for <tt>basic_istream::ignore()</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#TC">TC</a>&nbsp; <b>Submitter:</b>&nbsp;Greg Comeau, Dietmar K&uuml;hl&nbsp; <b>Date:</b>&nbsp;23 Jul 1999</p>
<p>In 27.6.1.1 <a href="lib-iostreams.html#lib.istream"> [lib.istream]</a> the function
<tt>ignore()</tt> gets an object of type <tt>streamsize</tt> as first
argument. However, in 27.6.1.3 <a href="lib-iostreams.html#lib.istream.unformatted"> [lib.istream.unformatted]</a>
paragraph 23 the first argument is of type <tt>int.</tt></p>

<p>As far as I can see this is not really a contradiction because
everything is consistent if <tt>streamsize</tt> is typedef to be
<tt>int</tt>. However, this is almost certainly not what was
intended. The same thing happened to <tt>basic_filebuf::setbuf()</tt>,
as described in issue <a href="lwg-defects.html#173">173</a>.</p>

<p>Darin Adler also
submitted this issue, commenting: Either 27.6.1.1 should be modified
to show a first parameter of type int, or 27.6.1.3 should be modified
to show a first parameter of type streamsize and use
numeric_limits&lt;streamsize&gt;::max.</p>
<p><b>Proposed resolution:</b></p>
<p>In 27.6.1.3 <a href="lib-iostreams.html#lib.istream.unformatted"> [lib.istream.unformatted]</a> paragraph 23 and 24, change both uses
of <tt>int</tt> in the description of <tt>ignore()</tt> to
<tt>streamsize</tt>.</p>
<hr>
<a name="173"><h3>173.&nbsp;Inconsistent types for <tt>basic_filebuf::setbuf()</tt>
</h3></a><p><b>Section:</b>&nbsp;27.8.1.4 <a href="lib-iostreams.html#lib.filebuf.virtuals"> [lib.filebuf.virtuals]</a>&nbsp; <b>Status:</b>&nbsp;<a href="lwg-active.html#TC">TC</a>&nbsp; <b>Submitter:</b>&nbsp;Greg Comeau, Dietmar K&uuml;hl&nbsp; <b>Date:</b>&nbsp;23 Jul 1999</p>

<p>
In 27.8.1.1 <a href="lib-iostreams.html#lib.filebuf"> [lib.filebuf]</a> the function <tt>setbuf()</tt> gets an
object of type <tt>streamsize</tt> as second argument. However, in
27.8.1.4 <a href="lib-iostreams.html#lib.filebuf.virtuals"> [lib.filebuf.virtuals]</a> paragraph 9 the second argument is of type
<tt>int</tt>.
</p>

<p>
As far as I can see this is not really a contradiction because
everything is consistent if <tt>streamsize</tt> is typedef to be
<tt>int</tt>. However, this is almost certainly not what was
intended. The same thing happened to <tt>basic_istream::ignore()</tt>,
as described in issue <a href="lwg-defects.html#172">172</a>.
</p>

<p><b>Proposed resolution:</b></p>
<p>In 27.8.1.4 <a href="lib-iostreams.html#lib.filebuf.virtuals"> [lib.filebuf.virtuals]</a> paragraph 9, change all uses of
<tt>int</tt> in the description of <tt>setbuf()</tt> to
<tt>streamsize</tt>.</p>
<hr>
<a name="174"><h3>174.&nbsp;Typo: <tt>OFF_T</tt> vs. <tt>POS_T</tt>
</h3></a><p><b>Section:</b>&nbsp;D.6 <a href="future.html#depr.ios.members"> [depr.ios.members]</a>&nbsp; <b>Status:</b>&nbsp;<a href="lwg-active.html#TC">TC</a>&nbsp; <b>Submitter:</b>&nbsp;Dietmar K&uuml;hl&nbsp; <b>Date:</b>&nbsp;23 Jul 1999</p>
<p>According to paragraph 1 of this section, <tt>streampos</tt> is the
type <tt>OFF_T</tt>, the same type as <tt>streamoff</tt>. However, in
paragraph 6 the <tt>streampos</tt> gets the type <tt>POS_T</tt></p>
<p><b>Proposed resolution:</b></p>
<p>Change D.6 <a href="future.html#depr.ios.members"> [depr.ios.members]</a> paragraph 1 from "<tt>typedef
OFF_T streampos;</tt>" to "<tt>typedef POS_T
streampos;</tt>"</p>
<hr>
<a name="175"><h3>175.&nbsp;Ambiguity for <tt>basic_streambuf::pubseekpos()</tt> and a few other functions.</h3></a><p><b>Section:</b>&nbsp;D.6 <a href="future.html#depr.ios.members"> [depr.ios.members]</a>&nbsp; <b>Status:</b>&nbsp;<a href="lwg-active.html#TC">TC</a>&nbsp; <b>Submitter:</b>&nbsp;Dietmar K&uuml;hl&nbsp; <b>Date:</b>&nbsp;23 Jul 1999</p>
<p>According to paragraph 8 of this section, the methods
<tt>basic_streambuf::pubseekpos()</tt>,
<tt>basic_ifstream::open()</tt>, and <tt>basic_ofstream::open</tt>
"may" be overloaded by a version of this function taking the
type <tt>ios_base::open_mode</tt> as last argument argument instead of
<tt>ios_base::openmode</tt> (<tt>ios_base::open_mode</tt> is defined
in this section to be an alias for one of the integral types). The
clause specifies, that the last argument has a default argument in
three cases.  However, this generates an ambiguity with the overloaded
version because now the arguments are absolutely identical if the last
argument is not specified.</p>
<p><b>Proposed resolution:</b></p>
<p>In D.6 <a href="future.html#depr.ios.members"> [depr.ios.members]</a> paragraph 8, remove the default arguments for
<tt>basic_streambuf::pubseekpos()</tt>,
<tt>basic_ifstream::open()</tt>, and
<tt>basic_ofstream::open().</tt></p>
<hr>
<a name="176"><h3>176.&nbsp;<tt>exceptions()</tt> in <tt>ios_base</tt>...?</h3></a><p><b>Section:</b>&nbsp;D.6 <a href="future.html#depr.ios.members"> [depr.ios.members]</a>&nbsp; <b>Status:</b>&nbsp;<a href="lwg-active.html#TC">TC</a>&nbsp; <b>Submitter:</b>&nbsp;Dietmar K&uuml;hl&nbsp; <b>Date:</b>&nbsp;23 Jul 1999</p>
<p>The "overload" for the function <tt>exceptions()</tt> in
paragraph 8 gives the impression that there is another function of
this function defined in class <tt>ios_base</tt>. However, this is not
the case. Thus, it is hard to tell how the semantics (paragraph 9) can
be implemented: "Call the corresponding member function specified
in clause 27 <a href="lib-iostreams.html#lib.input.output"> [lib.input.output]</a>."</p>
<p><b>Proposed resolution:</b></p>
<p>In D.6 <a href="future.html#depr.ios.members"> [depr.ios.members]</a> paragraph 8, move the declaration of the
function <tt>exceptions()</tt>into class <tt>basic_ios</tt>.</p>
<hr>
<a name="179"><h3>179.&nbsp;Comparison of const_iterators to iterators doesn't work</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#WP">WP</a>&nbsp; <b>Submitter:</b>&nbsp;Judy Ward&nbsp; <b>Date:</b>&nbsp;2 Jul 1998</p>
<p>Currently the following will not compile on two well-known standard
library implementations:</p>

<blockquote>
  <pre>#include &lt;set&gt;
using namespace std;

void f(const set&lt;int&gt; &amp;s)
{
  set&lt;int&gt;::iterator i;
  if (i==s.end()); // s.end() returns a const_iterator
}</pre>
</blockquote>

<p>
The reason this doesn't compile is because operator== was implemented
as a member function of the nested classes set:iterator and
set::const_iterator, and there is no conversion from const_iterator to
iterator. Surprisingly, (s.end() == i) does work, though, because of
the conversion from iterator to const_iterator.
</p>

<p>
I don't see a requirement anywhere in the standard that this must
work. Should there be one?  If so, I think the requirement would need
to be added to the tables in section 24.1.1. I'm not sure about the
wording.  If this requirement existed in the standard, I would think
that implementors would have to make the comparison operators
non-member functions.</p>

<p>This issues was also raised on comp.std.c++ by Darin
Adler.&nbsp; The example given was:</p>

<blockquote>
  <pre>bool check_equal(std::deque&lt;int&gt;::iterator i,
std::deque&lt;int&gt;::const_iterator ci)
{
return i == ci;
}</pre>
</blockquote>

<p>Comment from John Potter:</p>
<blockquote>
    <p>
    In case nobody has noticed, accepting it will break reverse_iterator.
    </p>

    <p>
    The fix is to make the comparison operators templated on two types.
    </p>

    <pre>
    template &lt;class Iterator1, class Iterator2&gt;
    bool operator== (reverse_iterator&lt;Iterator1&gt; const&amp; x,
                     reverse_iterator&lt;Iterator2&gt; const&amp; y);
    </pre>

    <p>
    Obviously:  return x.base() == y.base();
    </p>

    <p>
    Currently, no reverse_iterator to const_reverse_iterator compares are
    valid.
    </p>

    <p>
    BTW, I think the issue is in support of bad code.  Compares should be
    between two iterators of the same type.  All std::algorithms require
    the begin and end iterators to be of the same type. 
    </p>
</blockquote>
<p><b>Proposed resolution:</b></p>
<p>Insert this paragraph after 23.1 <a href="lib-containers.html#lib.container.requirements"> [lib.container.requirements]</a> paragraph 7:</p>
<blockquote>
  <p>In the expressions</p>
  <pre>
    i == j
    i != j
    i &lt; j
    i &lt;= j
    i &gt;= j
    i &gt; j
    i - j
  </pre>
  <p>Where i and j denote objects of a container's iterator type,
  either or both may be replaced by an object of the container's
  const_iterator type referring to the same element with no
  change in semantics.</p>
</blockquote>

<p><i>[post-Toronto: Judy supplied a proposed resolution saying that
<tt>iterator</tt> and <tt>const_iterator</tt> could be freely mixed in
iterator comparison and difference operations.]</i></p>

<p><i>[Redmond: Dave and Howard supplied a new proposed resolution which
explicitly listed expressions; there was concern that the previous
proposed resolution was too informal.]</i></p>
<p><b>Rationale:</b></p>
<p>
The LWG believes it is clear that the above wording applies only to
the nested types <tt>X::iterator</tt> and <tt>X::const_iterator</tt>,
where <tt>X</tt> is a container.  There is no requirement that
<tt>X::reverse_iterator</tt> and <tt>X::const_reverse_iterator</tt>
can be mixed.  If mixing them is considered important, that's a
separate issue.  (Issue <a href="lwg-active.html#280">280</a>.)
</p>
<hr>
<a name="181"><h3>181.&nbsp;make_pair() unintended behavior</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#TC">TC</a>&nbsp; <b>Submitter:</b>&nbsp;Andrew Koenig&nbsp; <b>Date:</b>&nbsp;3 Aug 1999</p>
<p>The claim has surfaced in Usenet that expressions such as<br>
<br>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; <tt>make_pair("abc", 3)</tt><br>
<br>
are illegal, notwithstanding their use in examples, because template instantiation tries to bind the first template
parameter to <tt> const char (&amp;)[4]</tt>, which type is uncopyable.<br>
<br>
I doubt anyone intended that behavior...
</p>
<p><b>Proposed resolution:</b></p>
<p>In 20.2 <a href="lib-utilities.html#lib.utility"> [lib.utility]</a>, paragraph 1 change the following
declaration of make_pair():</p>
<blockquote>
  <pre>template &lt;class T1, class T2&gt; pair&lt;T1,T2&gt; make_pair(const T1&amp;, const T2&amp;);</pre>
</blockquote>
<p>to:</p>
<blockquote>
  <pre>template &lt;class T1, class T2&gt; pair&lt;T1,T2&gt; make_pair(T1, T2);</pre>
</blockquote>
<p>  In 20.2.2 <a href="lib-utilities.html#lib.pairs"> [lib.pairs]</a> paragraph 7 and the line before, change:</p>
<blockquote>
<pre>template &lt;class T1, class T2&gt;
pair&lt;T1, T2&gt; make_pair(const T1&amp; x, const T2&amp; y);</pre>
</blockquote>
<p>to:</p>
<blockquote>
<pre>template &lt;class T1, class T2&gt;
pair&lt;T1, T2&gt; make_pair(T1 x, T2 y);</pre>
</blockquote>
<p>and add the following footnote to the effects clause:</p>
<blockquote>
  <p> According to 12.8 [class.copy], an implementation is permitted
  to not perform a copy of an argument, thus avoiding unnecessary
  copies.</p>
</blockquote>
<p><b>Rationale:</b></p>
<p>Two potential fixes were suggested by Matt Austern and Dietmar
K&uuml;hl, respectively, 1) overloading with array arguments, and 2) use of
a reference_traits class with a specialization for arrays.  Andy
Koenig suggested changing to pass by value. In discussion, it appeared
that this was a much smaller change to the standard that the other two
suggestions, and any efficiency concerns were more than offset by the
advantages of the solution. Two implementors reported that the
proposed resolution passed their test suites.</p>
<hr>
<a name="182"><h3>182.&nbsp;Ambiguous references to size_t</h3></a><p><b>Section:</b>&nbsp;17 <a href="lib-intro.html#lib.library"> [lib.library]</a>&nbsp; <b>Status:</b>&nbsp;<a href="lwg-active.html#WP">WP</a>&nbsp; <b>Submitter:</b>&nbsp;Al Stevens&nbsp; <b>Date:</b>&nbsp;15 Aug 1999</p>
<p>Many references to <tt> size_t</tt> throughout the document
omit the <tt> std::</tt> namespace qualification.</p> <p>For
example, 17.4.3.4 <a href="lib-intro.html#lib.replacement.functions"> [lib.replacement.functions]</a> paragraph 2:</p>
<blockquote>
<pre>&#151; operator new(size_t)
&#151; operator new(size_t, const std::nothrow_t&amp;)
&#151; operator new[](size_t)
&#151; operator new[](size_t, const std::nothrow_t&amp;)</pre>
</blockquote>
<p><b>Proposed resolution:</b></p>
<p>   In 17.4.3.4 <a href="lib-intro.html#lib.replacement.functions"> [lib.replacement.functions]</a> paragraph 2: replace:</p>
<blockquote>
<p><tt>     - operator new(size_t)<br>
     - operator new(size_t, const std::nothrow_t&amp;)<br>
     - operator new[](size_t)<br>
     - operator new[](size_t, const std::nothrow_t&amp;)</tt></p>
</blockquote>
<p>    by:</p>
<blockquote>
<pre>- operator new(std::size_t)
- operator new(std::size_t, const std::nothrow_t&amp;)
- operator new[](std::size_t)
- operator new[](std::size_t, const std::nothrow_t&amp;)</pre>
</blockquote>
<p>In [lib.allocator.requirements] 20.1.5, paragraph 4: replace:</p>
<blockquote>
  <p>The typedef members pointer, const_pointer, size_type, and difference_type
  are required to be T*, T const*, size_t, and ptrdiff_t, respectively.</p>
</blockquote>
<p>&nbsp;by:</p>
<blockquote>
  <p>The typedef members pointer, const_pointer, size_type, and difference_type
  are required to be T*, T const*, std::size_t, and std::ptrdiff_t,
  respectively.</p>
</blockquote>
<p>In [lib.allocator.members] 20.4.1.1, paragraphs 3 and 6: replace:</p>
<blockquote>
  <p>3 Notes: Uses ::operator new(size_t) (18.4.1).</p>
  <p>6 Note: the storage is obtained by calling ::operator new(size_t), but it
  is unspecified when or how often this function is called. The use of hint is
  unspecified, but intended as an aid to locality if an implementation so
  desires.</p>
</blockquote>
<p>by:</p>
<blockquote>
  <p>3 Notes: Uses ::operator new(std::size_t) (18.4.1).</p>
  <p>6 Note: the storage is obtained by calling ::operator new(std::size_t), but
  it is unspecified when or how often this function is called. The use of hint
  is unspecified, but intended as an aid to locality if an implementation so
  desires.</p>
</blockquote>
<p>In [lib.char.traits.require] 21.1.1, paragraph 1: replace:</p>
<blockquote>
  <p>In Table 37, X denotes a Traits class defining types and functions for the
  character container type CharT; c and d denote values of type CharT; p and q
  denote values of type const CharT*; s denotes a value of type CharT*; n, i and
  j denote values of type size_t; e and f denote values of type X::int_type; pos
  denotes a value of type X::pos_type; and state denotes a value of type X::state_type.</p>
</blockquote>
<p>by:</p>
<blockquote>
  <p>In Table 37, X denotes a Traits class defining types and functions for the
  character container type CharT; c and d denote values of type CharT; p and q
  denote values of type const CharT*; s denotes a value of type CharT*; n, i and
  j denote values of type std::size_t; e and f denote values of type X::int_type;
  pos denotes a value of type X::pos_type; and state denotes a value of type X::state_type.</p>
</blockquote>
<p>In [lib.char.traits.require] 21.1.1, table 37: replace the return type of
X::length(p): "size_t" by "std::size_t".</p>
<p>   In [lib.std.iterator.tags] 24.3.3, paragraph 2:    replace:<br>
&nbsp;&nbsp;&nbsp; typedef ptrdiff_t difference_type;<br>
    by:<br>
&nbsp;&nbsp;&nbsp; typedef std::ptrdiff_t difference_type;</p>
<p>   In [lib.locale.ctype] 22.2.1.1 put namespace std { ...} around the declaration of    template &lt;class charT&gt; class ctype.<br>
<br>
   In [lib.iterator.traits] 24.3.1, paragraph 2    put namespace std { ...} around the declaration of:<br>
<br>
&nbsp;&nbsp;&nbsp; template&lt;class Iterator&gt; struct iterator_traits<br>
&nbsp;&nbsp;&nbsp; template&lt;class T&gt; struct iterator_traits&lt;T*&gt;<br>
&nbsp;&nbsp;&nbsp; template&lt;class T&gt; struct iterator_traits&lt;const T*&gt;</p>
<p><b>Rationale:</b></p>
<p>The LWG believes correcting names like <tt>size_t</tt> and
<tt>ptrdiff_t</tt> to <tt>std::size_t</tt> and <tt>std::ptrdiff_t</tt>
to be essentially editorial.  There there can't be another size_t or
ptrdiff_t meant anyway because, according to 17.4.3.1.4 <a href="lib-intro.html#lib.extern.types"> [lib.extern.types]</a>,</p>

<blockquote>
For each type T from the Standard C library, the types ::T and std::T
are reserved to the implementation and, when defined, ::T shall be
identical to std::T.
</blockquote>

<p>The issue is treated as a Defect Report to make explicit the Project
Editor's authority to make this change.</p>

<p><i>[Post-Tokyo: Nico Josuttis provided the above wording at the
request of the LWG.]</i></p>

<p><i>[Toronto: This is tangentially related to issue <a href="lwg-defects.html#229">229</a>, but only tangentially: the intent of this issue is to
address use of the name <tt>size_t</tt> in contexts outside of
namespace std, such as in the description of <tt>::operator new</tt>.
The proposed changes should be reviewed to make sure they are
correct.]</i></p>

<p><i>[pre-Copenhagen: Nico has reviewed the changes and believes
them to be correct.]</i></p>

<hr>
<a name="183"><h3>183.&nbsp;I/O stream manipulators don't work for wide character streams</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#WP">WP</a>&nbsp; <b>Submitter:</b>&nbsp;Andy Sawyer&nbsp; <b>Date:</b>&nbsp;7 Jul 1999</p>
<p>27.6.3 <a href="lib-iostreams.html#lib.std.manip"> [lib.std.manip]</a> paragraph 3 says (clause numbering added for
exposition):</p>
<blockquote>
<p>Returns: An object s of unspecified type such that if [1] out is an (instance
of) basic_ostream then the expression out&lt;&lt;s behaves as if f(s) were
called, and if [2] 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: ios_base&amp;
f(ios_base&amp; str, ios_base::fmtflags mask) { // reset specified flags
str.setf(ios_base::fmtflags(0), mask); return str; } [3] The expression
out&lt;&lt;s has type ostream&amp; and value out. [4] The expression in&gt;&gt;s
has type istream&amp; and value in.</p>
</blockquote>
<p>Given the definitions [1] and [2] for out and in, surely [3] should read:
"The expression out &lt;&lt; s has type basic_ostream&amp; ..." and
[4] should read: "The expression in &gt;&gt; s has type basic_istream&amp;
..."</p>
<p>If the wording in the standard is correct, I can see no way of implementing
any of the manipulators so that they will work with wide character streams.</p>
<p>e.g. wcout &lt;&lt; setbase( 16 );</p>
<p>Must have value 'wcout' (which makes sense) and type 'ostream&amp;' (which
doesn't).</p>
<p>The same "cut'n'paste" type also seems to occur in Paras 4,5,7 and
8. In addition, Para 6 [setfill] has a similar error, but relates only to
ostreams.</p>
<p>I'd be happier if there was a better way of saying this, to make it clear
that the value of the expression is "the same specialization of
basic_ostream as out"&amp;</p>
<p><b>Proposed resolution:</b></p>
<p>Replace section 27.6.3 <a href="lib-iostreams.html#lib.std.manip"> [lib.std.manip]</a> except paragraph 1 with the
following:</p>
<blockquote>
<p>2- The type designated smanip in each of the following function descriptions is implementation-specified and may be different for each
function.<br>
<br>
<tt>smanip resetiosflags(ios_base::fmtflags mask);</tt><br>
<br>
-3- Returns: An object s of unspecified type such that if out is an instance of basic_ostream&lt;charT,traits&gt; then the expression out&lt;&lt;s behaves
as if f(s, mask) were called, or if in is an instance of basic_istream&lt;charT,traits&gt; then the expression in&gt;&gt;s behaves as if
f(s, mask) were called. The function f can be defined as:*<br>
<br>
[Footnote: The expression cin &gt;&gt; resetiosflags(ios_base::skipws) clears ios_base::skipws in the format flags stored in the
basic_istream&lt;charT,traits&gt; object cin (the same as cin &gt;&gt; noskipws), and the expression cout &lt;&lt; resetiosflags(ios_base::showbase) clears
ios_base::showbase in the format flags stored in the basic_ostream&lt;charT,traits&gt; object cout (the same as cout &lt;&lt;
noshowbase). --- end footnote]<br>
<br>
&nbsp;&nbsp;&nbsp;&nbsp; <tt>ios_base&amp; f(ios_base&amp; str, ios_base::fmtflags mask)<br>
&nbsp;&nbsp; {<br>
&nbsp;&nbsp; //  reset specified flags<br>
&nbsp;&nbsp; str.setf(ios_base::fmtflags(0), mask);<br>
&nbsp;&nbsp; return str;<br>
&nbsp;&nbsp; }<br>
</tt><br>
The expression out&lt;&lt;s has type basic_ostream&lt;charT,traits&gt;&amp; and value out.
The expression in&gt;&gt;s has type basic_istream&lt;charT,traits&gt;&amp; and value in.<br>
<br>
&nbsp;<tt>smanip setiosflags(ios_base::fmtflags mask);</tt><br>
<br>
-4- Returns: An object s of unspecified type such that if out is an instance of basic_ostream&lt;charT,traits&gt; then the expression out&lt;&lt;s behaves
as if f(s, mask) were called, or if in is an instance of basic_istream&lt;charT,traits&gt; then the expression in&gt;&gt;s behaves as if f(s,
mask) were called. The function f can be defined as:<br>
<br>
&nbsp;&nbsp;&nbsp;&nbsp; <tt>ios_base&amp; f(ios_base&amp; str, ios_base::fmtflags mask)<br>
&nbsp;&nbsp; {<br>
&nbsp;&nbsp; //  set specified flags<br>
&nbsp;&nbsp; str.setf(mask);<br>
&nbsp;&nbsp; return str;<br>
&nbsp;&nbsp; }<br>
</tt><br>
The expression out&lt;&lt;s has type basic_ostream&lt;charT,traits&gt;&amp; and value out.
The expression in&gt;&gt;s has type basic_istream&lt;charT,traits&gt;&amp; and value in.<br>
<br>
<tt>smanip setbase(int base);</tt><br>
<br>
-5- Returns: An object s of unspecified type such that if out is an instance of basic_ostream&lt;charT,traits&gt; then the expression out&lt;&lt;s behaves
as if f(s, base) were called, or if in is an instance of basic_istream&lt;charT,traits&gt; then the expression in&gt;&gt;s behaves as if f(s,
base) were called. The function f can be defined as:<br>
<br>
&nbsp;&nbsp;&nbsp;&nbsp; <tt>ios_base&amp; f(ios_base&amp; str, int base)<br>
&nbsp;&nbsp; {<br>
&nbsp;&nbsp; //  set  basefield<br>
&nbsp;&nbsp; str.setf(base ==  8 ? ios_base::oct :<br>
&nbsp;&nbsp; base == 10 ? ios_base::dec :<br>
&nbsp;&nbsp; base == 16 ? ios_base::hex :<br>
&nbsp;&nbsp; ios_base::fmtflags(0), ios_base::basefield);<br>
&nbsp;&nbsp; return str;<br>
&nbsp;&nbsp; }<br>
</tt><br>
The expression out&lt;&lt;s has type basic_ostream&lt;charT,traits&gt;&amp; and value out.
The expression in&gt;&gt;s has type basic_istream&lt;charT,traits&gt;&amp; and value in.<br>
<br>
<tt>smanip setfill(char_type c);<br>
</tt><br>
-6- Returns: An object s of unspecified type such that if out is (or is derived from) basic_ostream&lt;charT,traits&gt; and c has type charT then the
expression out&lt;&lt;s behaves as if f(s, c) were called. The function f can be
defined as:<br>
<br>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; <tt>template&lt;class charT, class traits&gt;<br>
&nbsp;&nbsp; basic_ios&lt;charT,traits&gt;&amp; f(basic_ios&lt;charT,traits&gt;&amp; str, charT c)<br>
&nbsp;&nbsp; {<br>
&nbsp;&nbsp; //  set fill character<br>
&nbsp;&nbsp; str.fill(c);<br>
&nbsp;&nbsp; return str;<br>
&nbsp;&nbsp; }<br>
</tt><br>
The expression out&lt;&lt;s has type basic_ostream&lt;charT,traits&gt;&amp; and value out.<br>
<br>
<tt>smanip setprecision(int n);</tt><br>
<br>
-7- Returns: An object s of unspecified type such that if out is an instance of basic_ostream&lt;charT,traits&gt; then the expression out&lt;&lt;s behaves
as if f(s, n) were called, or if in is an instance of basic_istream&lt;charT,traits&gt; then the expression in&gt;&gt;s behaves as if f(s, n)
were called. The function f can be defined as:<br>
<br>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; <tt>ios_base&amp; f(ios_base&amp; str, int n)<br>
&nbsp;&nbsp; {<br>
&nbsp;&nbsp; //  set precision<br>
&nbsp;&nbsp; str.precision(n);<br>
&nbsp;&nbsp; return str;<br>
&nbsp;&nbsp; }<br>
</tt><br>
The expression out&lt;&lt;s has type basic_ostream&lt;charT,traits&gt;&amp; and value out.
The expression in&gt;&gt;s has type basic_istream&lt;charT,traits&gt;&amp; and value in<br>
.<br>
<tt>smanip setw(int n);<br>
</tt><br>
-8- Returns: An object s of unspecified type such that if out is an instance of basic_ostream&lt;charT,traits&gt; then the expression out&lt;&lt;s behaves
as if f(s, n) were called, or if in is an instance of basic_istream&lt;charT,traits&gt; then the expression in&gt;&gt;s behaves as if f(s, n)
were called. The function f can be defined as:<br>
<br>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; <tt>ios_base&amp; f(ios_base&amp; str, int n)<br>
&nbsp;&nbsp; {<br>
&nbsp;&nbsp; //  set width<br>
&nbsp;&nbsp; str.width(n);<br>
&nbsp;&nbsp; return str;<br>
&nbsp;&nbsp; }<br>
</tt><br>
The expression out&lt;&lt;s has type
basic_ostream&lt;charT,traits&gt;&amp; and value out.  The expression
in&gt;&gt;s has type basic_istream&lt;charT,traits&gt;&amp; and value
in.
</p>
</blockquote>

<p><i>[Kona: Andy Sawyer and Beman Dawes will work to improve the wording of
the proposed resolution.]</i></p>

<p><i>[Tokyo - The LWG noted that issue <a href="lwg-closed.html#216">216</a> involves
the same paragraphs.]</i></p>

<p><i>[Post-Tokyo: The issues list maintainer combined the proposed
resolution of this issue with the proposed resolution for issue <a href="lwg-closed.html#216">216</a> as they both involved the same paragraphs, and were so
intertwined that dealing with them separately appear fraught with
error.  The full text was supplied by Bill Plauger; it was cross
checked against changes supplied by Andy Sawyer. It should be further
checked by the LWG.]</i></p>
<hr>
<a name="184"><h3>184.&nbsp;numeric_limits&lt;bool&gt; wording problems</h3></a><p><b>Section:</b>&nbsp;18.2.1.5 <a href="lib-support.html#lib.numeric.special"> [lib.numeric.special]</a>&nbsp; <b>Status:</b>&nbsp;<a href="lwg-active.html#WP">WP</a>&nbsp; <b>Submitter:</b>&nbsp;Gabriel Dos Reis&nbsp; <b>Date:</b>&nbsp;21 Jul 1999</p>
<p>bools are defined by the standard to be of integer types, as per
3.9.1 <a href="basic.html#basic.fundamental"> [basic.fundamental]</a> paragraph 7.  However "integer types"
seems to have a special meaning for the author of 18.2. The net effect
is an unclear and confusing specification for
numeric_limits&lt;bool&gt; as evidenced below.</p>

<p>18.2.1.2/7 says numeric_limits&lt;&gt;::digits is, for built-in integer
types, the number of non-sign bits in the representation.</p>

<p>4.5/4 states that a bool promotes to int ; whereas 4.12/1 says any non zero
arithmetical value converts to true.</p>

<p>I don't think it makes sense at all to require
numeric_limits&lt;bool&gt;::digits and numeric_limits&lt;bool&gt;::digits10 to
be meaningful.</p>

<p>The standard defines what constitutes a signed (resp. unsigned) integer
types. It doesn't categorize bool as being signed or unsigned. And the set of
values of bool type has only two elements.</p>

<p>I don't think it makes sense to require numeric_limits&lt;bool&gt;::is_signed
to be meaningful.</p>

<p>18.2.1.2/18 for numeric_limits&lt;integer_type&gt;::radix&nbsp; says:</p>
<blockquote>
  <p>For integer types, specifies the base of the representation.186)</p>
</blockquote>

<p>This disposition is at best misleading and confusing for the standard
requires a "pure binary numeration system" for integer types as per
3.9.1/7</p>

<p>The footnote 186) says: "Distinguishes types with base other than 2 (e.g
BCD)."&nbsp; This also erroneous as the standard never defines any integer
types with base representation other than 2.</p>

<p>Furthermore, numeric_limits&lt;bool&gt;::is_modulo and
numeric_limits&lt;bool&gt;::is_signed have similar problems.</p>
<p><b>Proposed resolution:</b></p>
<p>Append to the end of 18.2.1.5 <a href="lib-support.html#lib.numeric.special"> [lib.numeric.special]</a>:</p>
<blockquote>
  <p>The specialization for bool shall be provided as follows:</p>
  <pre>    namespace std {
       template&lt;&gt; class numeric_limits&lt;bool&gt; {
       public:
         static const bool is_specialized = true;
         static bool min() throw() { return false; }
         static bool max() throw() { return true; }

         static const int  digits = 1;
         static const int  digits10 = 0;
         static const bool is_signed = false;
         static const bool is_integer = true;
         static const bool is_exact = true;
         static const int  radix = 2;
         static bool epsilon() throw() { return 0; }
         static bool round_error() throw() { return 0; }

         static const int  min_exponent = 0;
         static const int  min_exponent10 = 0;
         static const int  max_exponent = 0;
         static const int  max_exponent10 = 0;

         static const bool has_infinity = false;
         static const bool has_quiet_NaN = false;
         static const bool has_signaling_NaN = false;
         static const float_denorm_style has_denorm = denorm_absent;
         static const bool has_denorm_loss = false;
         static bool infinity() throw() { return 0; }
         static bool quiet_NaN() throw() { return 0; }
         static bool signaling_NaN() throw() { return 0; }
         static bool denorm_min() throw() { return 0; }

         static const bool is_iec559 = false;
         static const bool is_bounded = true;
         static const bool is_modulo = false;

         static const bool traps = false;
         static const bool tinyness_before = false;
         static const float_round_style round_style = round_toward_zero;
       };
     }</pre>
</blockquote>

<p><i>[Tokyo:&nbsp; The LWG desires wording that specifies exact values
rather than more general wording in the original proposed
resolution.]</i></p>

<p><i>[Post-Tokyo:&nbsp; At the request of the LWG in Tokyo, Nico
Josuttis provided the above wording.]</i></p>
<hr>
<a name="185"><h3>185.&nbsp;Questionable use of term "inline"</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#WP">WP</a>&nbsp; <b>Submitter:</b>&nbsp;UK Panel&nbsp; <b>Date:</b>&nbsp;26 Jul 1999</p>
<p>Paragraph 4 of 20.3 <a href="lib-utilities.html#lib.function.objects"> [lib.function.objects]</a> says:</p>
<blockquote>
  <p>&nbsp;[Example: To negate every element of a: transform(a.begin(), a.end(),
  a.begin(), negate&lt;double&gt;()); The corresponding functions will inline
  the addition and the negation. end example]</p>
</blockquote>
<p>(Note: The "addition" referred to in the above is in para 3) we can
find no other wording, except this (non-normative) example which suggests that
any "inlining" will take place in this case.</p>
<p>Indeed both:</p>
<blockquote>
  <p>17.4.4.3 Global Functions [lib.global.functions] 1 It is
  unspecified whether any global functions in the C++ Standard Library
  are defined as inline (7.1.2).</p>
</blockquote>
<p>and</p>
<blockquote>
  <p>17.4.4.4 Member Functions [lib.member.functions] 1 It is
  unspecified whether any member functions in the C++ Standard Library
  are defined as inline (7.1.2).</p>
</blockquote>
<p>take care to state that this may indeed NOT be the case.</p>
<p>Thus the example "mandates" behavior that is explicitly
not required elsewhere.</p>
<p><b>Proposed resolution:</b></p>
<p>In 20.3 <a href="lib-utilities.html#lib.function.objects"> [lib.function.objects]</a> paragraph 1, remove the sentence:</p>
<blockquote>
<p>They are important for the effective use of the library.</p>
</blockquote>
<p>Remove 20.3 <a href="lib-utilities.html#lib.function.objects"> [lib.function.objects]</a> paragraph 2, which reads:</p>
<blockquote>
  <p> Using function objects together with function templates
  increases the expressive power of the library as well as making the
  resulting code much more efficient.</p>
</blockquote>
<p>In 20.3 <a href="lib-utilities.html#lib.function.objects"> [lib.function.objects]</a> paragraph 4, remove the sentence:</p>
<blockquote>
  <p>The corresponding functions will inline the addition and the
  negation.</p>
</blockquote>

<p><i>[Kona: The LWG agreed there was a defect.]</i></p>
<p><i>[Tokyo: The LWG crafted the proposed resolution.]</i></p>
<hr>
<a name="186"><h3>186.&nbsp;bitset::set() second parameter should be bool</h3></a><p><b>Section:</b>&nbsp;23.3.5.2 <a href="lib-containers.html#lib.bitset.members"> [lib.bitset.members]</a>&nbsp; <b>Status:</b>&nbsp;<a href="lwg-active.html#WP">WP</a>&nbsp; <b>Submitter:</b>&nbsp;Darin Adler&nbsp; <b>Date:</b>&nbsp;13 Aug 1999</p>
<p>In section 23.3.5.2 <a href="lib-containers.html#lib.bitset.members"> [lib.bitset.members]</a>, paragraph 13 defines the
bitset::set operation to take a second parameter of type int. The
function tests whether this value is non-zero to determine whether to
set the bit to true or false. The type of this second parameter should
be bool. For one thing, the intent is to specify a Boolean value. For
another, the result type from test() is bool. In addition, it's
possible to slice an integer that's larger than an int. This can't
happen with bool, since conversion to bool has the semantic of
translating 0 to false and any non-zero value to true.</p>
<p><b>Proposed resolution:</b></p>
<p>In 23.3.5 <a href="lib-containers.html#lib.template.bitset"> [lib.template.bitset]</a> Para 1 Replace:</p>
<blockquote>
<pre>bitset&lt;N&gt;&amp; set(size_t pos, int val = true ); </pre>
</blockquote>
<p>With:</p>
<blockquote>
  <pre>bitset&lt;N&gt;&amp; set(size_t pos, bool val = true );</pre>
</blockquote>
<p>In 23.3.5.2 <a href="lib-containers.html#lib.bitset.members"> [lib.bitset.members]</a> Para 12(.5) Replace:</p>
<blockquote>
  <pre>bitset&lt;N&gt;&amp; set(size_t pos, int val = 1 );</pre>
</blockquote>
<p>With:</p>
<blockquote>
  <pre>bitset&lt;N&gt;&amp; set(size_t pos, bool val = true );</pre>
</blockquote>

<p><i>[Kona: The LWG agrees with the description.&nbsp; Andy Sawyer will work
on better P/R wording.]</i></p>
<p><i>[Post-Tokyo: Andy provided the above wording.]</i></p>
<p><b>Rationale:</b></p>
<p><tt>bool</tt> is a better choice.  It is believed that binary
compatibility is not an issue, because this member function is
usually implemented as <tt>inline</tt>, and because it is already
the case that users cannot rely on the type of a pointer to a
nonvirtual member of a standard library class.</p>
<hr>
<a name="187"><h3>187.&nbsp;iter_swap underspecified</h3></a><p><b>Section:</b>&nbsp;25.2.2 <a href="lib-algorithms.html#lib.alg.swap"> [lib.alg.swap]</a>&nbsp; <b>Status:</b>&nbsp;<a href="lwg-active.html#WP">WP</a>&nbsp; <b>Submitter:</b>&nbsp;Andrew Koenig&nbsp; <b>Date:</b>&nbsp;14 Aug 1999</p>
<p>The description of iter_swap in 25.2.2 paragraph 7,says that it
``exchanges the values'' of the objects to which two iterators
refer.<br> <br> What it doesn't say is whether it does so using swap
or using the assignment operator and copy constructor.<br> <br> This
question is an important one to answer, because swap is specialized to
work efficiently for standard containers.<br> For example:</p>
<blockquote>
<pre>vector&lt;int&gt; v1, v2;
iter_swap(&amp;v1, &amp;v2);</pre>
</blockquote>
<p>Is this call to iter_swap equivalent to calling swap(v1, v2)?&nbsp;
Or is it equivalent to</p>
<blockquote>
<pre>{
vector&lt;int&gt; temp = v1;
v1 = v2;
v2 = temp;
}</pre>
</blockquote>
<p>The first alternative is O(1); the second is O(n).</p>
<p>A LWG member, Dave Abrahams, comments:</p>
<blockquote>
<p>Not an objection necessarily, but I want to point out the cost of
that requirement:</p>
  <blockquote>
<p><tt>iter_swap(list&lt;T&gt;::iterator, list&lt;T&gt;::iterator)</tt></p>
  </blockquote>
<p>can currently be specialized to be more efficient than
iter_swap(T*,T*) for many T (by using splicing). Your proposal would
make that optimization illegal.&nbsp;</p>
</blockquote>

<p><i>[Kona: The LWG notes the original need for iter_swap was proxy iterators
which are no longer permitted.]</i></p>
<p><b>Proposed resolution:</b></p>
<p>Change the effect clause of iter_swap in 25.2.2 paragraph 7 from:</p>
<blockquote>
<p>Exchanges the values pointed to by the two iterators a and b.</p>
</blockquote>
<p>to</p>
<blockquote>
<p><tt>swap(*a, *b)</tt>.</p>
</blockquote>

<p><b>Rationale:</b></p>
<p>It's useful to say just what <tt>iter_swap</tt> does.  There may be
  some iterators for which we want to specialize <tt>iter_swap</tt>,
  but the fully general version should have a general specification.</p>

<p>Note that in the specific case of <tt>list&lt;T&gt;::iterator</tt>,
iter_swap should not be specialized as suggested above.  That would do
much more than exchanging the two iterators' values: it would change
predecessor/successor relationships, possibly moving the iterator from
one list to another.  That would surely be inappropriate.</p>
<hr>
<a name="189"><h3>189.&nbsp;setprecision() not specified correctly</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#TC">TC</a>&nbsp; <b>Submitter:</b>&nbsp;Andrew Koenig&nbsp; <b>Date:</b>&nbsp;25 Aug 1999</p>
<p>27.4.2.2 paragraph 9 claims that setprecision() sets the precision,
and includes a parenthetical note saying that it is the number of
digits after the decimal point.<br>
<br>
This claim is not strictly correct.  For example, in the default
floating-point output format, setprecision sets the number of
significant digits printed, not the number of digits after the decimal
point.<br>
<br>
I would like the committee to look at the definition carefully and
correct the statement in 27.4.2.2</p>
<p><b>Proposed resolution:</b></p>
<p>Remove from 27.4.2.2 <a href="lib-iostreams.html#lib.fmtflags.state"> [lib.fmtflags.state]</a>, paragraph 9, the text
"(number of digits after the decimal point)".</p>
<hr>
<a name="193"><h3>193.&nbsp;Heap operations description incorrect</h3></a><p><b>Section:</b>&nbsp;25.3.6 <a href="lib-algorithms.html#lib.alg.heap.operations"> [lib.alg.heap.operations]</a>&nbsp; <b>Status:</b>&nbsp;<a href="lwg-active.html#TC">TC</a>&nbsp; <b>Submitter:</b>&nbsp;Markus Mauhart&nbsp; <b>Date:</b>&nbsp;24 Sep 1999</p>
<p>25.3.6 [lib.alg.heap.operations] states two key properties of a heap [a,b), the first of them
is<br>
<br>
&nbsp;&nbsp;&nbsp; `"(1) *a is the largest element"<br>
<br>
I think this is incorrect and should be changed to the wording in the proposed
resolution.</p>
<p>Actually there are two independent changes:</p>
<blockquote>
  <p>A-"part of largest equivalence class" instead of "largest", cause 25.3
  [lib.alg.sorting] asserts "strict weak ordering" for all its sub clauses.</p>
  <p>B-Take 'an oldest' from that equivalence class, otherwise the heap functions  could not be used for a
  priority queue as explained in 23.2.3.2.2 [lib.priqueue.members] (where I assume that a "priority queue" respects  priority AND time).</p>
</blockquote>
<p><b>Proposed resolution:</b></p>
<p>Change 25.3.6 <a href="lib-algorithms.html#lib.alg.heap.operations"> [lib.alg.heap.operations]</a> property (1) from:</p>
<blockquote>
  <p>(1) *a is the largest element</p>
</blockquote>
<p>to:</p>
<blockquote>
  <p>(1) There is no element greater than <tt>*a</tt></p>
</blockquote>
<hr>
<a name="195"><h3>195.&nbsp;Should <tt>basic_istream::sentry</tt>'s constructor ever set eofbit?</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#TC">TC</a>&nbsp; <b>Submitter:</b>&nbsp;Matt Austern&nbsp; <b>Date:</b>&nbsp;13 Oct 1999</p>
<p>Suppose that <tt>is.flags() &amp; ios_base::skipws</tt> is nonzero.
What should <tt>basic_istream&lt;&gt;::sentry</tt>'s constructor do if it
reaches eof while skipping whitespace?  27.6.1.1.2/5 suggests it
should set failbit. Should it set eofbit as well?  The standard
doesn't seem to answer that question.</p>

<p>On the one hand, nothing in 27.6.1.1.2 <a href="lib-iostreams.html#lib.istream::sentry"> [lib.istream::sentry]</a> says that
<tt>basic_istream&lt;&gt;::sentry</tt> should ever set eofbit.  On the
other hand, 27.6.1.1 <a href="lib-iostreams.html#lib.istream"> [lib.istream]</a> paragraph 4 says that if
extraction from a <tt>streambuf</tt> "returns
<tt>traits::eof()</tt>, then the input function, except as explicitly
noted otherwise, completes its actions and does
<tt>setstate(eofbit)"</tt>.  So the question comes down to
whether <tt>basic_istream&lt;&gt;::sentry</tt>'s constructor is an
input function.</p>

<p>Comments from Jerry Schwarz:</p>
<blockquote>
<p>It was always my intention that eofbit should be set any time that a
virtual returned something to indicate eof, no matter what reason
iostream code had for calling the virtual.</p>
<p>
The motivation for this is that I did not want to require streambufs
to behave consistently if their virtuals are called after they have
signaled eof.</p>
<p>
The classic case is a streambuf reading from a UNIX file.  EOF isn't
really a state for UNIX file descriptors.  The convention is that a
read on UNIX returns 0 bytes to indicate "EOF", but the file
descriptor isn't shut down in any way and future reads do not
necessarily also return 0 bytes.  In particular, you can read from
tty's on UNIX even after they have signaled "EOF".  (It
isn't always understood that a ^D on UNIX is not an EOF indicator, but
an EOL indicator.  By typing a "line" consisting solely of
^D you cause a read to return 0 bytes, and by convention this is
interpreted as end of file.)</p>
</blockquote>
<p><b>Proposed resolution:</b></p>
<p>Add a sentence to the end of 27.6.1.1.2 paragraph 2:</p>
<blockquote>
<p>If <tt>is.rdbuf()-&gt;sbumpc()</tt> or <tt>is.rdbuf()-&gt;sgetc()</tt>
returns <tt>traits::eof()</tt>, the function calls
<tt>setstate(failbit | eofbit)</tt> (which may throw
<tt>ios_base::failure</tt>).
</p>
</blockquote>
<hr>
<a name="198"><h3>198.&nbsp;Validity of pointers and references unspecified after iterator destruction</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#WP">WP</a>&nbsp; <b>Submitter:</b>&nbsp;Beman Dawes&nbsp; <b>Date:</b>&nbsp;3 Nov 1999</p>
<p>
Is a pointer or reference obtained from an iterator still valid after
destruction of the iterator?
</p>
<p>
Is a pointer or reference obtained from an iterator still valid after the value
of the iterator changes?
</p>
<blockquote>
<pre>
#include &lt;iostream&gt;
#include &lt;vector&gt;
#include &lt;iterator&gt;

int main()
{
    typedef std::vector&lt;int&gt; vec_t;
    vec_t v;
    v.push_back( 1 );

    // Is a pointer or reference obtained from an iterator still
    // valid after destruction of the iterator?
    int * p = &amp;*v.begin();
    std::cout &lt;&lt; *p &lt;&lt; '\n';  // OK?

    // Is a pointer or reference obtained from an iterator still
    // valid after the value of the iterator changes?
    vec_t::iterator iter( v.begin() );
    p = &amp;*iter++;
    std::cout &lt;&lt; *p &lt;&lt; '\n';  // OK?

    return 0;
}
</pre>
</blockquote>

<p>The standard doesn't appear to directly address these
questions. The standard needs to be clarified. At least two real-world
cases have been reported where library implementors wasted
considerable effort because of the lack of clarity in the
standard. The question is important because requiring pointers and
references to remain valid has the effect for practical purposes of
prohibiting iterators from pointing to cached rather than actual
elements of containers.</p>

<p>The standard itself assumes that pointers and references obtained
from an iterator are still valid after iterator destruction or
change. The definition of reverse_iterator::operator*(), 24.4.1.3.3 <a href="lib-iterators.html#lib.reverse.iter.op.star"> [lib.reverse.iter.op.star]</a>, which returns a reference, defines
effects:</p>

<blockquote>
  <pre>Iterator tmp = current;
return *--tmp;</pre>
</blockquote>
<p>The definition of reverse_iterator::operator-&gt;(), 24.4.1.3.4 <a href="lib-iterators.html#lib.reverse.iter.opref"> [lib.reverse.iter.opref]</a>, which returns a pointer, defines effects:</p>
<blockquote>
  <pre>return &amp;(operator*());</pre>
</blockquote>

<p>Because the standard itself assumes pointers and references remain
valid after iterator destruction or change, the standard should say so
explicitly. This will also reduce the chance of user code breaking
unexpectedly when porting to a different standard library
implementation.</p>
<p><b>Proposed resolution:</b></p>
<p>Add a new paragraph to 24.1 <a href="lib-iterators.html#lib.iterator.requirements"> [lib.iterator.requirements]</a>:</p>
<blockquote>
Destruction of an iterator may invalidate pointers and references
previously obtained from that iterator.
</blockquote>

<p>Replace paragraph 1 of 24.4.1.3.3 <a href="lib-iterators.html#lib.reverse.iter.op.star"> [lib.reverse.iter.op.star]</a> with:</p>

<blockquote>
<p><b>Effects:</b></p>
<pre>
  this-&gt;tmp = current;
  --this-&gt;tmp;
  return *this-&gt;tmp;
</pre>

<p>
[<i>Note:</i> This operation must use an auxiliary member variable,
rather than a temporary variable, to avoid returning a reference that
persists beyond the lifetime of its associated iterator.  (See
24.1 <a href="lib-iterators.html#lib.iterator.requirements"> [lib.iterator.requirements]</a>.)  The name of this member variable is shown for
exposition only.  <i>--end note</i>]
</p>
</blockquote>

<p><i>[Post-Tokyo: The issue has been reformulated purely
in terms of iterators.]</i></p>

<p><i>[Pre-Toronto: Steve Cleary pointed out the no-invalidation
assumption by reverse_iterator. The issue and proposed resolution was
reformulated yet again to reflect this reality.]</i></p>

<p><i>[Copenhagen: Steve Cleary pointed out that reverse_iterator
assumes its underlying iterator has persistent pointers and
references.  Andy Koenig pointed out that it is possible to rewrite
reverse_iterator so that it no longer makes such an assupmption.
However, this issue is related to issue <a href="lwg-active.html#299">299</a>.  If we
decide it is intentional that <tt>p[n]</tt> may return by value
instead of reference when <tt>p</tt> is a Random Access Iterator,
other changes in reverse_iterator will be necessary.]</i></p>
<p><b>Rationale:</b></p>
<p>This issue has been discussed extensively.  Note that it is
<i>not</i> an issue about the behavior of predefined iterators.  It is
asking whether or not user-defined iterators are permitted to have
transient pointers and references.  Several people presented examples
of useful user-defined iterators that have such a property; examples
include a B-tree iterator, and an "iota iterator" that doesn't point
to memory.  Library implementors already seem to be able to cope with
such iterators: they take pains to avoid forming references to memory
that gets iterated past.  The only place where this is a problem is
<tt>reverse_iterator</tt>, so this issue changes
<tt>reverse_iterator</tt> to make it work.</p>

<p>This resolution does not weaken any guarantees provided by
predefined iterators like <tt>list&lt;int&gt;::iterator</tt>.
Clause 23 should be reviewed to make sure that guarantees for
predefined iterators are as strong as users expect.</p>

<hr>
<a name="199"><h3>199.&nbsp;What does <tt>allocate(0)</tt> return?</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#TC">TC</a>&nbsp; <b>Submitter:</b>&nbsp;Matt Austern&nbsp; <b>Date:</b>&nbsp;19 Nov 1999</p>
<p>
Suppose that <tt>A</tt> is a class that conforms to the
Allocator requirements of Table 32, and <tt>a</tt> is an
object of class <tt>A</tt>  What should be the return
value of <tt>a.allocate(0)</tt>?  Three reasonable
possibilities: forbid the argument <tt>0</tt>, return
a null pointer, or require that the return value be a
unique non-null pointer.
</p>
<p><b>Proposed resolution:</b></p>
<p>
Add a note to the <tt>allocate</tt> row of Table 32:
"[<i>Note:</i> If <tt>n == 0</tt>, the return value is unspecified. <i>--end note</i>]"</p>
<p><b>Rationale:</b></p>
<p>A key to understanding this issue is that the ultimate use of
allocate() is to construct an iterator, and that iterator for zero
length sequences must be the container's past-the-end
representation.  Since this already implies special case code, it
would be over-specification to mandate the return value.
</p>
<hr>
<a name="200"><h3>200.&nbsp;Forward iterator requirements don't allow constant iterators</h3></a><p><b>Section:</b>&nbsp;24.1.3 <a href="lib-iterators.html#lib.forward.iterators"> [lib.forward.iterators]</a>&nbsp; <b>Status:</b>&nbsp;<a href="lwg-active.html#WP">WP</a>&nbsp; <b>Submitter:</b>&nbsp;Matt Austern&nbsp; <b>Date:</b>&nbsp;19 Nov 1999</p>
<p>
In table 74, the return type of the expression <tt>*a</tt> is given
as <tt>T&amp;</tt>, where <tt>T</tt> is the iterator's value type.
For constant iterators, however, this is wrong.  ("Value type"
is never defined very precisely, but it is clear that the value type
of, say, <tt>std::list&lt;int&gt;::const_iterator</tt> is supposed to be
<tt>int</tt>, not <tt>const int</tt>.)
</p>
<p><b>Proposed resolution:</b></p>
<p>
In table 74, in the <tt>*a</tt> and <tt>*r++</tt> rows, change the
return type from "<tt>T&amp;</tt>" to "<tt>T&amp;</tt>
if <tt>X</tt> is mutable, otherwise <tt>const T&amp;</tt>".
In the <tt>a-&gt;m</tt> row, change the return type from
"<tt>U&amp;</tt>" to "<tt>U&amp;</tt> if <tt>X</tt> is mutable,
otherwise <tt>const U&amp;</tt>".
</p>

<p><i>[Tokyo: The LWG believes this is the tip of a larger iceberg;
there are multiple const problems with the STL portion of the library
and that these should be addressed as a single package.&nbsp; Note
that issue <a href="lwg-closed.html#180">180</a> has already been declared NAD Future for
that very reason.]</i></p>

<p><i>[Redmond: the LWG thinks this is separable from other constness
issues.  This issue is just cleanup; it clarifies language that was
written before we had iterator_traits.  Proposed resolution was
modified: the original version only discussed *a.  It was pointed out
that we also need to worry about *r++ and a-&gt;m.]</i></p>

<hr>
<a name="202"><h3>202.&nbsp;unique() effects unclear when predicate not an equivalence relation</h3></a><p><b>Section:</b>&nbsp;25.2.8 <a href="lib-algorithms.html#lib.alg.unique"> [lib.alg.unique]</a>&nbsp; <b>Status:</b>&nbsp;<a href="lwg-active.html#WP">WP</a>&nbsp; <b>Submitter:</b>&nbsp;Andrew Koenig&nbsp; <b>Date:</b>&nbsp;13 Jan 2000</p>
<p>
What should unique() do if you give it a predicate that is not an
equivalence relation?  There are at least two plausible answers:
</p>

<blockquote>

<p>
   1. You can't, because 25.2.8 says that it it "eliminates all but
   the first element from every consecutive group of equal
   elements..." and it wouldn't make sense to interpret "equal" as
   meaning anything but an equivalence relation.  [It also doesn't
   make sense to interpret "equal" as meaning ==, because then there
   would never be any sense in giving a predicate as an argument at
   all.]
</p>

<p>
   2. The word "equal" should be interpreted to mean whatever the
   predicate says, even if it is not an equivalence relation
   (and in particular, even if it is not transitive).
</p>

</blockquote>

<p>
The example that raised this question is from Usenet:
</p>

<blockquote>

<pre>int f[] = { 1, 3, 7, 1, 2 };
int* z = unique(f, f+5, greater&lt;int&gt;());</pre>

</blockquote>

<p>
If one blindly applies the definition using the predicate
greater&lt;int&gt;, and ignore the word "equal", you get:
</p>

<blockquote>

<p>
    Eliminates all but the first element from every consecutive group    
    of elements referred to by the iterator i in the range [first, last)    
    for which *i &gt; *(i - 1).
</p>

</blockquote>

<p>
The first surprise is the order of the comparison.  If we wanted to
allow for the predicate not being an equivalence relation, then we
should surely compare elements the other way: pred(*(i - 1), *i).  If
we do that, then the description would seem to say: "Break the
sequence into subsequences whose elements are in strictly increasing
order, and keep only the first element of each subsequence".  So the
result would be 1, 1, 2.  If we take the description at its word, it
would seem to call for strictly DEcreasing order, in which case the
result should be 1, 3, 7, 2.<br>
<br>
In fact, the SGI implementation of unique() does neither: It yields 1,
3, 7.
</p>
<p><b>Proposed resolution:</b></p>
<p>Change 25.2.8 <a href="lib-algorithms.html#lib.alg.unique"> [lib.alg.unique]</a> paragraph 1 to:</p>
<blockquote>
For a nonempty range, eliminates all but the first element from every
consecutive group of equivalent elements referred to by the iterator
<tt>i</tt> in the range [first+1, last) for which the following
conditions hold: <tt>*(i-1) == *i</tt> or <tt>pred(*(i-1), *i) !=
false</tt>.
</blockquote>

<p>
Also insert a new paragraph, paragraph 2a, that reads: "Requires: The
comparison function must be an equivalence relation."
</p>

<p><i>[Redmond: discussed arguments for and against requiring the
comparison function to be an equivalence relation.  Straw poll:
14-2-5.  First number is to require that it be an equivalence
relation, second number is to explicitly not require that it be an
equivalence relation, third number is people who believe they need
more time to consider the issue.  A separate issue: Andy Sawyer
pointed out that "i-1" is incorrect, since "i" can refer to the first
iterator in the range.  Matt provided wording to address this
problem.]</i></p>

<p><i>[Cura&ccedil;ao: The LWG changed "... the range (first,
last)..." to "...  the range [first+1, last)..." for
clarity. They considered this change close enough to editorial to not
require another round of review.]</i></p>

<p><b>Rationale:</b></p>
<p>The LWG also considered an alternative resolution: change 
25.2.8 <a href="lib-algorithms.html#lib.alg.unique"> [lib.alg.unique]</a> paragraph 1 to:</p>

<blockquote>
For a nonempty range, eliminates all but the first element from every
consecutive group of elements referred to by the iterator
<tt>i</tt> in the range (first, last) for which the following
conditions hold: <tt>*(i-1) == *i</tt> or <tt>pred(*(i-1), *i) !=
false</tt>.
</blockquote>

<p>
Also insert a new paragraph, paragraph 1a, that reads: "Notes: The
comparison function need not be an equivalence relation."
</p>


<p>Informally: the proposed resolution imposes an explicit requirement
that the comparison function be an equivalence relation.  The
alternative resolution does not, and it gives enough information so
that the behavior of unique() for a non-equivalence relation is
specified.  Both resolutions are consistent with the behavior of
existing implementations.</p>
<hr>
<a name="208"><h3>208.&nbsp;Unnecessary restriction on past-the-end iterators</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#TC">TC</a>&nbsp; <b>Submitter:</b>&nbsp;Stephen Cleary&nbsp; <b>Date:</b>&nbsp;02 Feb 2000</p>
<p>In 24.1 paragraph 5, it is stated ". . . Dereferenceable and
past-the-end values are always non-singular."</p>
<p>This places an unnecessary restriction on past-the-end iterators for
containers with forward iterators (for example, a singly-linked list). If the
past-the-end value on such a container was a well-known singular value, it would
still satisfy all forward iterator requirements.</p>
<p>Removing this restriction would allow, for example, a singly-linked list
without a "footer" node.</p>
<p>This would have an impact on existing code that expects past-the-end
iterators obtained from different (generic) containers being not equal.</p>
<p><b>Proposed resolution:</b></p>
<p>Change 24.1 <a href="lib-iterators.html#lib.iterator.requirements"> [lib.iterator.requirements]</a> paragraph 5, the last sentence, from:</p>
<blockquote>
<p>Dereferenceable and past-the-end values are always non-singular.</p>
</blockquote>
<p>to:</p>
<blockquote>
<p>Dereferenceable values are always non-singular.&nbsp;</p>
</blockquote>
<p><b>Rationale:</b></p>
<p>For some kinds of containers, including singly linked lists and
zero-length vectors, null pointers are perfectly reasonable past-the-end
iterators.  Null pointers are singular.
</p>
<hr>
<a name="209"><h3>209.&nbsp;basic_string declarations inconsistent</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#TC">TC</a>&nbsp; <b>Submitter:</b>&nbsp;Igor Stauder&nbsp; <b>Date:</b>&nbsp;11 Feb 2000</p>
<p>In Section 21.3 <a href="lib-strings.html#lib.basic.string"> [lib.basic.string]</a> the basic_string member function
declarations use a consistent style except for the following functions:</p>
<blockquote>
  <pre>void push_back(const charT);
basic_string&amp; assign(const basic_string&amp;);
void swap(basic_string&lt;charT,traits,Allocator&gt;&amp;);</pre>
</blockquote>
<p>- push_back, assign, swap: missing argument name&nbsp;<br>
- push_back: use of const with charT (i.e. POD type passed by value
not by reference - should be charT or const charT&amp; )<br>
- swap: redundant use of template parameters in argument
basic_string&lt;charT,traits,Allocator&gt;&amp;</p>
<p><b>Proposed resolution:</b></p>
<p>In Section 21.3 <a href="lib-strings.html#lib.basic.string"> [lib.basic.string]</a> change the basic_string member
function declarations push_back, assign, and swap to:</p>
<blockquote>
  <pre>void push_back(charT c); 

basic_string&amp; assign(const basic_string&amp; str);
void swap(basic_string&amp; str);</pre>
</blockquote>
<p><b>Rationale:</b></p>
<p>Although the standard is in general not consistent in declaration
style, the basic_string declarations are consistent other than the
above.  The LWG felt that this was sufficient reason to merit the
change.
</p>
<hr>
<a name="210"><h3>210.&nbsp;distance first and last confused</h3></a><p><b>Section:</b>&nbsp;25 <a href="lib-algorithms.html#lib.algorithms"> [lib.algorithms]</a>&nbsp; <b>Status:</b>&nbsp;<a href="lwg-active.html#TC">TC</a>&nbsp; <b>Submitter:</b>&nbsp;Lisa Lippincott&nbsp; <b>Date:</b>&nbsp;15 Feb 2000</p>
<p>In paragraph 9 of section 25 <a href="lib-algorithms.html#lib.algorithms"> [lib.algorithms]</a>, it is written:</p>
<blockquote>
  <p>      In the description of the algorithms operators + and - are used
           for some of the iterator categories for which they do not have to
           be defined. In these cases the semantics of [...] a-b is the same
           as of<br>
  <br>
  &nbsp;&nbsp;&nbsp;&nbsp; <tt>return distance(a, b);</tt></p>
</blockquote>
<p><b>Proposed resolution:</b></p>
<p>On the last line of paragraph 9 of section 25 <a href="lib-algorithms.html#lib.algorithms"> [lib.algorithms]</a> change
<tt>"a-b"</tt> to <tt>"b-a".</tt></p>
<p><b>Rationale:</b></p>
<p>There are two ways to fix the defect; change the description to b-a
or change the return to distance(b,a).  The LWG preferred the
former for consistency.</p>
<hr>
<a name="211"><h3>211.&nbsp;operator&gt;&gt;(istream&amp;, string&amp;) doesn't set failbit</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#TC">TC</a>&nbsp; <b>Submitter:</b>&nbsp;Scott Snyder&nbsp; <b>Date:</b>&nbsp;4 Feb 2000</p>
<p>The description of the stream extraction operator for std::string (section
21.3.7.9 [lib.string.io]) does not contain a requirement that failbit be set in
the case that the operator fails to extract any characters from the input
stream.</p>
<p>This implies that the typical construction</p>
<blockquote>
  <pre>std::istream is;
std::string str;
...
while (is &gt;&gt; str) ... ;</pre>
</blockquote>
<p>(which tests failbit) is not required to terminate at EOF.</p>
<p>Furthermore, this is inconsistent with other extraction operators,
which do include this requirement. (See sections 27.6.1.2 <a href="lib-iostreams.html#lib.istream.formatted"> [lib.istream.formatted]</a> and 27.6.1.3 <a href="lib-iostreams.html#lib.istream.unformatted"> [lib.istream.unformatted]</a>), where this
requirement is present, either explicitly or implicitly, for the
extraction operators. It is also present explicitly in the description
of getline (istream&amp;, string&amp;, charT) in section 21.3.7.9 <a href="lib-strings.html#lib.string.io"> [lib.string.io]</a> paragraph 8.)</p>
<p><b>Proposed resolution:</b></p>
<p>Insert new paragraph after paragraph 2 in section 21.3.7.9 <a href="lib-strings.html#lib.string.io"> [lib.string.io]</a>:</p>
<blockquote>

<p>If the function extracts no characters, it calls
is.setstate(ios::failbit) which may throw ios_base::failure
(27.4.4.3).</p>
</blockquote>
<hr>
<a name="212"><h3>212.&nbsp;Empty range behavior unclear for several algorithms</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#TC">TC</a>&nbsp; <b>Submitter:</b>&nbsp;Nico Josuttis&nbsp; <b>Date:</b>&nbsp;26 Feb 2000</p>
<p>The standard doesn't specify what min_element() and max_element() shall
return if the range is empty (first equals last). The usual implementations
return last. This problem seems also apply to partition(), stable_partition(),
next_permutation(), and prev_permutation().</p>
<p><b>Proposed resolution:</b></p>
<p>In 25.3.7 <a href="lib-algorithms.html#lib.alg.min.max"> [lib.alg.min.max]</a> - Minimum and maximum, paragraphs 7 and
9, append: Returns last if first==last.</p>
<p><b>Rationale:</b></p>
<p>The LWG looked in some detail at all of the above mentioned
algorithms, but believes that except for min_element() and
max_element() it is already clear that last is returned if first ==
last.</p>
<hr>
<a name="214"><h3>214.&nbsp;set::find() missing const overload</h3></a><p><b>Section:</b>&nbsp;23.3.3 <a href="lib-containers.html#lib.set"> [lib.set]</a>, 23.3.4 <a href="lib-containers.html#lib.multiset"> [lib.multiset]</a>&nbsp; <b>Status:</b>&nbsp;<a href="lwg-active.html#WP">WP</a>&nbsp; <b>Submitter:</b>&nbsp;Judy Ward&nbsp; <b>Date:</b>&nbsp;28 Feb 2000</p>
<p>The specification for the associative container requirements in
Table 69 state that the find member function should "return
iterator; const_iterator for constant a". The map and multimap
container descriptions have two overloaded versions of find, but set
and multiset do not, all they have is:</p>
<blockquote>
  <pre>iterator find(const key_type &amp; x) const;</pre>
</blockquote>
<p><b>Proposed resolution:</b></p>
<p>Change the prototypes for find(), lower_bound(), upper_bound(), and
equal_range() in section 23.3.3 <a href="lib-containers.html#lib.set"> [lib.set]</a> and section 23.3.4 <a href="lib-containers.html#lib.multiset"> [lib.multiset]</a> to each have two overloads:</p>
<blockquote>
  <pre>iterator find(const key_type &amp; x);
const_iterator find(const key_type &amp; x) const;</pre>
  <pre>iterator lower_bound(const key_type &amp; x);
const_iterator lower_bound(const key_type &amp; x) const;</pre>
  <pre>iterator upper_bound(const key_type &amp; x);
const_iterator upper_bound(const key_type &amp; x) const;</pre>
  <pre>pair&lt;iterator, iterator&gt; equal_range(const key_type &amp; x);
pair&lt;const_iterator, const_iterator&gt; equal_range(const key_type &amp; x) const;</pre>
</blockquote>

<p><i>[Tokyo: At the request of the LWG, Judy Ward provided wording
extending the proposed resolution to lower_bound, upper_bound, and
equal_range.]</i></p>
<hr>
<a name="217"><h3>217.&nbsp;Facets example (Classifying Japanese characters) contains errors</h3></a><p><b>Section:</b>&nbsp;22.2.8 <a href="lib-locales.html#lib.facets.examples"> [lib.facets.examples]</a>&nbsp; <b>Status:</b>&nbsp;<a href="lwg-active.html#TC">TC</a>&nbsp; <b>Submitter:</b>&nbsp;Martin Sebor&nbsp; <b>Date:</b>&nbsp;29 Feb 2000</p>
<p>The example in 22.2.8, paragraph 11 contains the following errors:</p>
<p>1) The member function `My::JCtype::is_kanji()' is non-const; the function
must be const in order for it to be callable on a const object (a reference to
which which is what std::use_facet&lt;&gt;() returns).</p>
<p>2) In file filt.C, the definition of `JCtype::id' must be qualified with the
name of the namespace `My'.</p>
<p>3) In the definition of `loc' and subsequently in the call to use_facet&lt;&gt;()
in main(), the name of the facet is misspelled: it should read `My::JCtype'
rather than `My::JCType'.</p>
<p><b>Proposed resolution:</b></p>
<p>Replace the "Classifying Japanese characters" example in 22.2.8,
paragraph 11 with the following:</p>
<pre>#include &lt;locale&gt;</pre>
<pre>namespace My {
    using namespace std;
    class JCtype : public locale::facet {
    public:
        static locale::id id;     //  required for use as a new locale facet
        bool is_kanji (wchar_t c) const;
        JCtype() {}
    protected:
        ~JCtype() {}
    };
}</pre>
<pre>//  file:  filt.C
#include &lt;iostream&gt;
#include &lt;locale&gt;
#include "jctype"                 //  above
std::locale::id My::JCtype::id;   //  the static  JCtype  member
declared above.</pre>
<pre>int main()
{
    using namespace std;
    typedef ctype&lt;wchar_t&gt; wctype;
    locale loc(locale(""),              //  the user's preferred locale...
               new My::JCtype);         //  and a new feature ...
    wchar_t c = use_facet&lt;wctype&gt;(loc).widen('!');
    if (!use_facet&lt;My::JCtype&gt;(loc).is_kanji(c))
        cout &lt;&lt; "no it isn't!" &lt;&lt; endl;
    return 0;
}</pre>
<hr>
<a name="220"><h3>220.&nbsp;~ios_base() usage valid?</h3></a><p><b>Section:</b>&nbsp;27.4.2.7 <a href="lib-iostreams.html#lib.ios.base.cons"> [lib.ios.base.cons]</a>&nbsp; <b>Status:</b>&nbsp;<a href="lwg-active.html#TC">TC</a>&nbsp; <b>Submitter:</b>&nbsp;Jonathan Schilling, Howard Hinnant&nbsp; <b>Date:</b>&nbsp;13 Mar 2000</p>
<p>The pre-conditions for the ios_base destructor are described in 27.4.2.7
paragraph 2:</p>
<blockquote>
  <p>Effects: Destroys an object of class ios_base. Calls each registered
  callback pair (fn,index) (27.4.2.6) as (*fn)(erase_event,*this,index) at such
  time that any ios_base member function called from within fn has well defined
  results.</p>
</blockquote>
<p>But what is not clear is: If no callback functions were ever registered, does
it matter whether the ios_base members were ever initialized?</p>
<p>For instance, does this program have defined behavior:</p>
<blockquote>
  <pre>#include &lt;ios&gt;</pre>
  <pre>class D : public std::ios_base { };</pre>
  <pre>int main() { D d; }</pre>
</blockquote>
<p>It seems that registration of a callback function would surely affect the
state of an ios_base. That is, when you register a callback function with an
ios_base, the ios_base must record that fact somehow.</p>
<p>But if after construction the ios_base is in an indeterminate state, and that
state is not made determinate before the destructor is called, then how would
the destructor know if any callbacks had indeed been registered? And if the
number of callbacks that had been registered is indeterminate, then is not the
behavior of the destructor undefined?</p>
<p>By comparison, the basic_ios class description in 27.4.4.1 paragraph 2 makes
it explicit that destruction before initialization results in undefined
behavior.</p>
<p><b>Proposed resolution:</b></p>
<p>Modify 27.4.2.7 paragraph 1 from</p>
<blockquote>
  <p>Effects: Each ios_base member has an indeterminate value after
  construction.</p>
</blockquote>
<p>to</p>
<blockquote>
  <p>Effects: Each ios_base member has an indeterminate value after
  construction. These members must be initialized by calling basic_ios::init. If an ios_base object is destroyed before these initializations
  have taken place, the behavior is undefined.</p>
</blockquote>
<hr>
<a name="221"><h3>221.&nbsp;num_get&lt;&gt;::do_get stage 2 processing broken</h3></a><p><b>Section:</b>&nbsp;22.2.2.1.2 <a href="lib-locales.html#lib.facet.num.get.virtuals"> [lib.facet.num.get.virtuals]</a>&nbsp; <b>Status:</b>&nbsp;<a href="lwg-active.html#WP">WP</a>&nbsp; <b>Submitter:</b>&nbsp;Matt Austern&nbsp; <b>Date:</b>&nbsp;14 Mar 2000</p>
<p>Stage 2 processing of numeric conversion is broken.</p>

<p>Table 55 in 22.2.2.1.2 says that when basefield is 0 the integral
conversion specifier is %i. A %i specifier determines a number's base
by its prefix (0 for octal, 0x for hex), so the intention is clearly
that a 0x prefix is allowed.  Paragraph 8 in the same section,
however, describes very precisely how characters are processed. (It
must be done "as if" by a specified code fragment.) That
description does not allow a 0x prefix to be recognized.</p>

<p>Very roughly, stage 2 processing reads a char_type ct. It converts
ct to a char, not by using narrow but by looking it up in a
translation table that was created by widening the string literal
"0123456789abcdefABCDEF+-". The character "x" is
not found in that table, so it can't be recognized by stage 2
processing.</p>
<p><b>Proposed resolution:</b></p>
<p>In 22.2.2.1.2 paragraph 8, replace the line:</p>
<blockquote>
  <pre>static const char src[] = "0123456789abcdefABCDEF+-";</pre>
</blockquote>
<p>with the line:</p>
<blockquote>
  <pre>static const char src[] = "0123456789abcdefxABCDEFX+-";</pre>
</blockquote>
<p><b>Rationale:</b></p>
<p>If we're using the technique of widening a string literal, the
string literal must contain every character we wish to recognize.
This technique has the consequence that alternate representations
of digits will not be recognized.  This design decision was made
deliberately, with full knowledge of that limitation.</p>
<hr>
<a name="222"><h3>222.&nbsp;Are throw clauses necessary if a throw is already implied by the effects clause?</h3></a><p><b>Section:</b>&nbsp;17.3.1.3 <a href="lib-intro.html#lib.structure.specifications"> [lib.structure.specifications]</a>&nbsp; <b>Status:</b>&nbsp;<a href="lwg-active.html#TC">TC</a>&nbsp; <b>Submitter:</b>&nbsp;Judy Ward&nbsp; <b>Date:</b>&nbsp;17 Mar 2000</p>
<p>Section 21.3.6.8 describes the basic_string::compare function this way:</p>
<blockquote>
  <pre>21.3.6.8 - basic_string::compare [lib.string::compare]

int compare(size_type pos1, size_type n1,
                const basic_string&lt;charT,traits,Allocator&gt;&amp;  str ,
                size_type  pos2 , size_type  n2 ) const;

-4- Returns: 

    basic_string&lt;charT,traits,Allocator&gt;(*this,pos1,n1).compare(
                 basic_string&lt;charT,traits,Allocator&gt;(str,pos2,n2)) .</pre>
</blockquote>
<p>and the constructor that's implicitly called by the above is
defined to throw an out-of-range exception if pos &gt; str.size(). See
section 21.3.1 <a href="lib-strings.html#lib.string.cons"> [lib.string.cons]</a> paragraph 4.</p>

<p>On the other hand, the compare function descriptions themselves don't have
"Throws: " clauses and according to 17.3.1.3, paragraph 3, elements
that do not apply to a function are omitted.</p>
<p>So it seems there is an inconsistency in the standard -- are the
"Effects" clauses correct, or are the "Throws" clauses
missing?</p>
<p><b>Proposed resolution:</b></p>
<p>In 17.3.1.3 <a href="lib-intro.html#lib.structure.specifications"> [lib.structure.specifications]</a> paragraph 3, the footnote 148 attached to
the sentence "Descriptions of function semantics contain the
following elements (as appropriate):", insert the word
"further" so that the foot note reads:</p>
<blockquote>
  <p>To save space, items that do not apply to a function are
  omitted. For example, if a function does not specify any further
  preconditions, there will be no "Requires" paragraph.</p>
</blockquote>
<p><b>Rationale:</b></p>
<p>The standard is somewhat inconsistent, but a failure to note a
throw condition in a throws clause does not grant permission not to
throw.  The inconsistent wording is in a footnote, and thus
non-normative. The proposed resolution from the LWG clarifies the
footnote.</p>
<hr>
<a name="223"><h3>223.&nbsp;reverse algorithm should use iter_swap rather than swap</h3></a><p><b>Section:</b>&nbsp;25.2.9 <a href="lib-algorithms.html#lib.alg.reverse"> [lib.alg.reverse]</a>&nbsp; <b>Status:</b>&nbsp;<a href="lwg-active.html#TC">TC</a>&nbsp; <b>Submitter:</b>&nbsp;Dave Abrahams&nbsp; <b>Date:</b>&nbsp;21 Mar 2000</p>
<p>Shouldn't the effects say "applies iter_swap to all pairs..."?</p>
<p><b>Proposed resolution:</b></p>
<p>In 25.2.9 <a href="lib-algorithms.html#lib.alg.reverse"> [lib.alg.reverse]</a>, replace:</p>
  <blockquote>
  Effects: For each non-negative integer i &lt;= (last - first)/2, 
  applies swap to all pairs of iterators first + i, (last - i) - 1.
  </blockquote>
<p>with:</p>
  <blockquote>
  Effects: For each non-negative integer i &lt;= (last - first)/2, 
  applies iter_swap to all pairs of iterators first + i, (last - i) - 1.
  </blockquote>
<hr>
<a name="224"><h3>224.&nbsp;clear() complexity for associative containers refers to undefined N</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#TC">TC</a>&nbsp; <b>Submitter:</b>&nbsp;Ed Brey&nbsp; <b>Date:</b>&nbsp;23 Mar 2000</p>
<p>In the associative container requirements table in 23.1.2 paragraph 7,
a.clear() has complexity "log(size()) + N". However, the meaning of N
is not defined.</p>
<p><b>Proposed resolution:</b></p>
<p>In the associative container requirements table in 23.1.2 paragraph
7, the complexity of a.clear(), change "log(size()) + N" to
"linear in <tt>size()</tt>".</p>
<p><b>Rationale:</b></p>
<p>It's the "log(size())", not the "N", that is in
error: there's no difference between <i>O(N)</i> and <i>O(N +
log(N))</i>.  The text in the standard is probably an incorrect
cut-and-paste from the range version of <tt>erase</tt>.</p>
<hr>
<a name="225"><h3>225.&nbsp;std:: algorithms use of other unqualified algorithms</h3></a><p><b>Section:</b>&nbsp;17.4.4.3 <a href="lib-intro.html#lib.global.functions"> [lib.global.functions]</a>&nbsp; <b>Status:</b>&nbsp;<a href="lwg-active.html#WP">WP</a>&nbsp; <b>Submitter:</b>&nbsp;Dave Abrahams&nbsp; <b>Date:</b>&nbsp;01 Apr 2000</p>
<p>Are algorithms in std:: allowed to use other algorithms without qualification, so functions in
user namespaces might be found through Koenig lookup?</p>
<p>For example, a popular standard library implementation includes this
implementation of std::unique:</p>
<blockquote>
<pre>namespace std {
    template &lt;class _ForwardIter&gt;
    _ForwardIter unique(_ForwardIter __first, _ForwardIter __last) {
      __first = adjacent_find(__first, __last);
      return unique_copy(__first, __last, __first);
    }
    }</pre>
</blockquote>
<p>Imagine two users on opposite sides of town, each using unique on his own
sequences bounded by my_iterators . User1 looks at his standard library
implementation and says, "I know how to implement a more efficient
unique_copy for my_iterators", and writes:</p>
<blockquote>
<pre>namespace user1 {
    class my_iterator;
    // faster version for my_iterator
    my_iterator unique_copy(my_iterator, my_iterator, my_iterator);
    }</pre>
</blockquote>
<p>user1::unique_copy() is selected by Koenig lookup, as he intended.</p>
<p>User2 has other needs, and writes:</p>
<blockquote>
<pre>namespace user2 {
    class my_iterator;
    // Returns true iff *c is a unique copy of *a and *b.
    bool unique_copy(my_iterator a, my_iterator b, my_iterator c);
    }</pre>
</blockquote>
<p>User2 is shocked to find later that his fully-qualified use of
std::unique(user2::my_iterator, user2::my_iterator, user2::my_iterator) fails to
compile (if he's lucky). Looking in the standard, he sees the following Effects
clause for unique():</p>
<blockquote>
  <p>Effects: Eliminates all but the first element from every consecutive group
  of equal elements referred to by the iterator i in the range [first, last) for
  which the following corresponding conditions hold: *i == *(i - 1) or pred(*i,
  *(i - 1)) != false</p>
</blockquote>
<p>The standard gives user2 absolutely no reason to think he can interfere with
std::unique by defining names in namespace user2. His standard library has been
built with the template export feature, so he is unable to inspect the
implementation. User1 eventually compiles his code with another compiler, and
his version of unique_copy silently stops being called. Eventually, he realizes
that he was depending on an implementation detail of his library and had no
right to expect his unique_copy() to be called portably.</p>
<p>On the face of it, and given above scenario, it may seem obvious that the
implementation of unique() shown is non-conforming because it uses unique_copy()
rather than ::std::unique_copy(). Most standard library implementations,
however, seem to disagree with this notion.</p>
<p> <i>[Tokyo:&nbsp; Steve Adamczyk from
the core working group indicates that "std::" is sufficient;&nbsp;
leading "::" qualification is not required because any namespace
qualification is sufficient to suppress Koenig lookup.]</i></p>
<p><b>Proposed resolution:</b></p>
<p>Add a paragraph and a note at the end of 
17.4.4.3 <a href="lib-intro.html#lib.global.functions"> [lib.global.functions]</a>:</p>
<blockquote>

<p>Unless otherwise specified, no global or non-member function in the
standard library shall use a function from another namespace which is
found through <i>argument-dependent name lookup</i> (3.4.2 <a href="basic.html#basic.lookup.koenig"> [basic.lookup.koenig]</a>).</p>

<p>[Note: the phrase "unless otherwise specified" is intended to
allow Koenig lookup in cases like that of ostream_iterators:<br>

<br>
  Effects:</p>
  <blockquote>
<p>*out_stream &lt;&lt; value;<br>
      if(delim != 0) *out_stream &lt;&lt; delim;<br>
      return (*this);</p>
    <p>--end note]</p>
  </blockquote>
</blockquote>

<p><i>[Tokyo: The LWG agrees that this is a defect in the standard, but
is as yet unsure if the proposed resolution is the best
solution. Furthermore, the LWG believes that the same problem of
unqualified library names applies to wording in the standard itself,
and has opened issue <a href="lwg-defects.html#229">229</a> accordingly. Any resolution of
issue <a href="lwg-defects.html#225">225</a> should be coordinated with the resolution of
issue <a href="lwg-defects.html#229">229</a>.]</i></p>

<p><i>[Toronto: The LWG is not sure if this is a defect in the
standard.  Most LWG members believe that an implementation of
<tt>std::unique</tt> like the one quoted in this issue is already
illegal, since, under certain circumstances, its semantics are not
those specified in the standard.  The standard's description of
<tt>unique</tt> does not say that overloading <tt>adjacent_find</tt>
should have any effect.]</i></p>

<p><i>[Cura&ccedil;ao: An LWG-subgroup spent an afternoon working on issues
225, 226, and 229.  Their conclusion was that the issues should be
separated into an LWG portion (Howard's paper, N1387=02-0045), and a
EWG portion (Dave will write a proposal). The LWG and EWG had
(separate) discussions of this plan the next day.  The proposed
resolution for this issue is in accordance with Howard's paper.]</i></p>

<p><b>Rationale:</b></p>
<p>It could be argued that this proposed isn't strictly necessary,
  that the Standard doesn't grant implementors license to write a
  standard function that behaves differently than specified in the
  Standard just because of an unrelated user-defined name in some
  other namespace.  However, this is at worst a clarification.  It is
  surely right that algorithsm shouldn't pick up random names, that
  user-defined names should have no effect unless otherwise specified.
  Issue <a href="lwg-defects.html#226">226</a> deals with the question of when it is
  appropriate for the standard to explicitly specify otherwise.</p>
<hr>
<a name="226"><h3>226.&nbsp;User supplied specializations or overloads of namespace std function templates</h3></a><p><b>Section:</b>&nbsp;17.4.3.1 <a href="lib-intro.html#lib.reserved.names"> [lib.reserved.names]</a>&nbsp; <b>Status:</b>&nbsp;<a href="lwg-active.html#WP">WP</a>&nbsp; <b>Submitter:</b>&nbsp;Dave Abrahams&nbsp; <b>Date:</b>&nbsp;01 Apr 2000</p>
<p>The issues are:&nbsp;</p>
<p>1. How can a 3rd party library implementor (lib1) write a version of a standard
algorithm which is specialized to work with his own class template?&nbsp;</p>
<p>2. How can another library implementor (lib2) write a generic algorithm which 
will take advantage of the specialized algorithm in lib1?</p>
<p>This appears to be the only viable answer under current language rules:</p>
<blockquote>
  <pre>namespace lib1
{
    // arbitrary-precision numbers using T as a basic unit
    template &lt;class T&gt;
    class big_num { //...
    };
    </pre>
  <pre>    // defining this in namespace std is illegal (it would be an
    // overload), so we hope users will rely on Koenig lookup
    template &lt;class T&gt;
    void swap(big_int&lt;T&gt;&amp;, big_int&lt;T&gt;&amp;);
}</pre>
  <pre>#include &lt;algorithm&gt;
namespace lib2
{
    template &lt;class T&gt;
    void generic_sort(T* start, T* end)
    {
            ...
        // using-declaration required so we can work on built-in types
        using std::swap;
        // use Koenig lookup to find specialized algorithm if available
        swap(*x, *y);
    }
}</pre>
</blockquote>
<p>This answer has some drawbacks. First of all, it makes writing lib2 difficult
and somewhat slippery. The implementor needs to remember to write the
using-declaration, or generic_sort will fail to compile when T is a built-in
type. The second drawback is that the use of this style in lib2 effectively
"reserves" names in any namespace which defines types which may
eventually be used with lib2. This may seem innocuous at first when applied to
names like swap, but consider more ambiguous names like unique_copy() instead.
It is easy to imagine the user wanting to define these names differently in his
own namespace. A definition with semantics incompatible with the standard
library could cause serious problems (see issue <a href="lwg-defects.html#225">225</a>).</p>
<p>Why, you may ask, can't we just partially specialize std::swap()? It's
because the language doesn't allow for partial specialization of function
templates. If you write:</p>
<blockquote>
  <pre>namespace std
{
    template &lt;class T&gt;
    void swap(lib1::big_int&lt;T&gt;&amp;, lib1::big_int&lt;T&gt;&amp;);
}</pre>
</blockquote>
<p>You have just overloaded std::swap, which is illegal under the current
language rules. On the other hand, the following full specialization is legal:</p>
<blockquote>
  <pre>namespace std
{
    template &lt;&gt;
    void swap(lib1::other_type&amp;, lib1::other_type&amp;);
}</pre>
</blockquote>

<p>This issue reflects concerns raised by the "Namespace issue
with specialized swap" thread on comp.lang.c++.moderated. A
similar set of concerns was earlier raised on the boost.org mailing
list and the ACCU-general mailing list.  Also see library reflector
message c++std-lib-7354.</p>

<p>
J. C. van Winkel points out (in c++std-lib-9565) another unexpected
fact: it's impossible to output a container of std::pair's using copy
and an ostream_iterator, as long as both pair-members are built-in or
std:: types.  That's because a user-defined operator&lt;&lt; for (for
example) std::pair&lt;const std::string, int&gt; will not be found:
lookup for operator&lt;&lt; will be performed only in namespace std.
Opinions differed on whether or not this was a defect, and, if so,
whether the defect is that something is wrong with user-defined
functionality and std, or whether it's that the standard library does
not provide an operator&lt;&lt; for std::pair&lt;&gt;.
</p>

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

<p>Adopt the wording proposed in Howard Hinnant's paper
  N1523=03-0106, "Proposed Resolution To LWG issues 225, 226, 229".</p>


<p><i>[Tokyo: Summary, "There is no conforming way to extend
std::swap for user defined templates."&nbsp; The LWG agrees that
there is a problem.  Would like more information before
proceeding. This may be a core issue.  Core issue 229 has been opened
to discuss the core aspects of this problem. It was also noted that
submissions regarding this issue have been received from several
sources, but too late to be integrated into the issues list.
]</i></p>

<p><i>[Post-Tokyo: A paper with several proposed resolutions,
J16/00-0029==WG21/N1252, "Shades of namespace std functions
" by Alan Griffiths, is in the Post-Tokyo mailing. It
should be considered a part of this issue.]</i></p>

<p><i>[Toronto: Dave Abrahams and Peter Dimov have proposed a
resolution that involves core changes: it would add partial
specialization of function template.  The Core Working Group is
reluctant to add partial specialization of function templates.  It is
viewed as a large change, CWG believes that proposal presented leaves
some syntactic issues unanswered; if the CWG does add partial
specialization of function templates, it wishes to develop its own
proposal.  The LWG continues to believe that there is a serious
problem: there is no good way for users to force the library to use
user specializations of generic standard library functions, and in
certain cases (e.g. transcendental functions called by
<tt>valarray</tt> and <tt>complex</tt>) this is important.  Koenig
lookup isn't adequate, since names within the library must be
qualified with <tt>std</tt> (see issue 225), specialization doesn't
work (we don't have partial specialization of function templates), and
users aren't permitted to add overloads within namespace std.
]</i></p>

<p><i>[Copenhagen: Discussed at length, with no consensus.  Relevant
papers in the pre-Copenhagen mailing: N1289, N1295, N1296.  Discussion
focused on four options. (1) Relax restrictions on overloads within
namespace std. (2) Mandate that the standard library use unqualified
calls for <tt>swap</tt> and possibly other functions.  (3) Introduce
helper class templates for <tt>swap</tt> and possibly other functions.
(4) Introduce partial specialization of function templates.  Every
option had both support and opposition.  Straw poll (first number is
support, second is strongly opposed): (1) 6, 4; (2) 6, 7; (3) 3, 8;
(4) 4, 4.]</i></p>

<p><i>[Redmond: Discussed, again no consensus.  Herb presented an
argument that a user who is defining a type <tt>T</tt> with an
associated <tt>swap</tt> should not be expected to put that
<tt>swap</tt> in namespace std, either by overloading or by partial
specialization.  The argument is that <tt>swap</tt> is part of
<tt>T</tt>'s interface, and thus should to in the same namespace as
<tt>T</tt> and only in that namespace.  If we accept this argument,
the consequence is that standard library functions should use
unqualified call of <tt>swap</tt>.  (And which other functions? Any?)
A small group (Nathan, Howard, Jeremy, Dave, Matt, Walter, Marc) will
try to put together a proposal before the next meeting.]</i></p>

<p><i>[Cura&ccedil;ao: An LWG-subgroup spent an afternoon working on issues
225, 226, and 229.  Their conclusion was that the issues should be
separated into an LWG portion (Howard's paper, N1387=02-0045), and a
EWG portion (Dave will write a proposal). The LWG and EWG had
(separate) discussions of this plan the next day.  The proposed
resolution is the one proposed by Howard.]</i></p>

<p><i>[Santa Cruz: the LWG agreed with the general direction of
  Howard's paper, N1387.  (Roughly: Koenig lookup is disabled unless
  we say otherwise; this issue is about when we do say otherwise.)
  However, there were concerns about wording.  Howard will provide new
  wording.  Bill and Jeremy will review it.]</i></p>

<p><i>[Kona: Howard proposed the new wording.  The LWG accepted his
  proposed resolution.]</i></p>

<p><b>Rationale:</b></p>
<p>Informally: introduce a Swappable concept, and specify that the
  value types of the iterators passed to certain standard algorithms
  (such as iter_swap, swap_ranges, reverse, rotate, and sort) conform
  to that concept.  The Swappable concept will make it clear that
  these algorithms use unqualified lookup for the calls
  to <tt>swap</tt>.  Also, in 26.3.3.3 <a href="lib-numerics.html#lib.valarray.transcend"> [lib.valarray.transcend]</a> paragraph 1,
  state that the valarray transcendentals use unqualified lookup.</p>
<hr>
<a name="227"><h3>227.&nbsp;std::swap() should require CopyConstructible or DefaultConstructible arguments</h3></a><p><b>Section:</b>&nbsp;25.2.2 <a href="lib-algorithms.html#lib.alg.swap"> [lib.alg.swap]</a>&nbsp; <b>Status:</b>&nbsp;<a href="lwg-active.html#TC">TC</a>&nbsp; <b>Submitter:</b>&nbsp;Dave Abrahams&nbsp; <b>Date:</b>&nbsp;09 Apr 2000</p>
<p>25.2.2 reads:</p>
<blockquote>
  <p><tt>  template&lt;class T&gt; void swap(T&amp; a, T&amp; b);</tt><br>
  <br>
  Requires:    Type T is Assignable (_lib.container.requirements_).<br>
  Effects:    Exchanges values stored in two locations.</p>
</blockquote>
<p>The only reasonable** generic implementation of swap requires construction of a 
   new temporary copy of one of its arguments:</p>
<blockquote>
<pre>template&lt;class T&gt; void swap(T&amp; a, T&amp; b);
  {
      T tmp(a);
      a = b;
      b = tmp;
  }</pre>
</blockquote>
<p>But a type which is only Assignable cannot be swapped by this implementation.</p>
<p>**Yes, there's also an unreasonable implementation which would require T to be 
   DefaultConstructible instead of CopyConstructible. I don't think this is worthy 
   of consideration:</p>
<blockquote>
<pre>template&lt;class T&gt; void swap(T&amp; a, T&amp; b);
{
    T tmp;
    tmp = a;
    a = b;
    b = tmp;
}</pre>
</blockquote>
<p><b>Proposed resolution:</b></p>
<p>Change 25.2.2 paragraph 1 from:</p>
<blockquote>
<p>  Requires: Type T is Assignable (23.1).</p>
</blockquote>
<p>to:</p>
<blockquote>
<p>  Requires: Type T is CopyConstructible (20.1.3) and Assignable (23.1)</p>
</blockquote>
<hr>
<a name="228"><h3>228.&nbsp;Incorrect specification of "..._byname" facets</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#WP">WP</a>&nbsp; <b>Submitter:</b>&nbsp;Dietmar K&uuml;hl&nbsp; <b>Date:</b>&nbsp;20 Apr 2000</p>
<p>The sections 22.2.1.2 <a href="lib-locales.html#lib.locale.ctype.byname"> [lib.locale.ctype.byname]</a>, 22.2.1.4 <a href="lib-locales.html#lib.locale.ctype.byname.special"> [lib.locale.ctype.byname.special]</a>,
22.2.1.6 <a href="lib-locales.html#lib.locale.codecvt.byname"> [lib.locale.codecvt.byname]</a>, 22.2.3.2 <a href="lib-locales.html#lib.locale.numpunct.byname"> [lib.locale.numpunct.byname]</a>, 22.2.4.2 <a href="lib-locales.html#lib.locale.collate.byname"> [lib.locale.collate.byname]</a>, 22.2.5.4 <a href="lib-locales.html#lib.locale.time.put.byname"> [lib.locale.time.put.byname]</a>, 22.2.6.4 <a href="lib-locales.html#lib.locale.moneypunct.byname"> [lib.locale.moneypunct.byname]</a>, and 22.2.7.2 <a href="lib-locales.html#lib.locale.messages.byname"> [lib.locale.messages.byname]</a> overspecify the
definitions of the "..._byname" classes by listing a bunch
of virtual functions. At the same time, no semantics of these
functions are defined. Real implementations do not define these
functions because the functional part of the facets is actually
implemented in the corresponding base classes and the constructor of
the "..._byname" version just provides suitable date used by
these implementations. For example, the 'numpunct' methods just return
values from a struct. The base class uses a statically initialized
struct while the derived version reads the contents of this struct
from a table.  However, no virtual function is defined in
'numpunct_byname'.</p>

<p>For most classes this does not impose a problem but specifically
for 'ctype' it does: The specialization for 'ctype_byname&lt;char&gt;'
is required because otherwise the semantics would change due to the
virtual functions defined in the general version for 'ctype_byname':
In 'ctype&lt;char&gt;' the method 'do_is()' is not virtual but it is
made virtual in both 'ctype&lt;cT&gt;' and 'ctype_byname&lt;cT&gt;'.
Thus, a class derived from 'ctype_byname&lt;char&gt;' can tell whether
this class is specialized or not under the current specification:
Without the specialization, 'do_is()' is virtual while with
specialization it is not virtual.</p>
<p><b>Proposed resolution:</b></p>
<p>&nbsp; Change section 22.2.1.2 (lib.locale.ctype.byname) to become:</p>
<pre>     namespace std {
       template &lt;class charT&gt;
       class ctype_byname : public ctype&lt;charT&gt; {
       public:
         typedef ctype&lt;charT&gt;::mask mask;
         explicit ctype_byname(const char*, size_t refs = 0);
       protected:
        ~ctype_byname();             //  virtual
       };
     }</pre>
<p>&nbsp; Change section 22.2.1.6 (lib.locale.codecvt.byname) to become:</p>
<pre>    namespace std {
      template &lt;class internT, class externT, class stateT&gt;
      class codecvt_byname : public codecvt&lt;internT, externT, stateT&gt; {
      public:
       explicit codecvt_byname(const char*, size_t refs = 0);
      protected:
      ~codecvt_byname();             //  virtual
       };
     }
</pre>
<p>&nbsp; Change section 22.2.3.2 (lib.locale.numpunct.byname) to become:</p>
<pre>     namespace std {
       template &lt;class charT&gt;
       class numpunct_byname : public numpunct&lt;charT&gt; {
     //  this class is specialized for  char  and  wchar_t.
       public:
         typedef charT                char_type;
         typedef basic_string&lt;charT&gt;  string_type;
         explicit numpunct_byname(const char*, size_t refs = 0);
       protected:
        ~numpunct_byname();          //  virtual
       };
     }</pre>
<p>&nbsp; Change section 22.2.4.2 (lib.locale.collate.byname) to become:</p>
<pre>     namespace std {
       template &lt;class charT&gt;
       class collate_byname : public collate&lt;charT&gt; {
       public:
         typedef basic_string&lt;charT&gt; string_type;
         explicit collate_byname(const char*, size_t refs = 0);
       protected:
        ~collate_byname();           //  virtual
       };
     }</pre>
<p>&nbsp; Change section 22.2.5.2 (lib.locale.time.get.byname) to become:</p>
<pre>     namespace std {
       template &lt;class charT, class InputIterator = istreambuf_iterator&lt;charT&gt; &gt;
       class time_get_byname : public time_get&lt;charT, InputIterator&gt; {
       public:
         typedef time_base::dateorder dateorder;
         typedef InputIterator        iter_type</pre>
<pre>         explicit time_get_byname(const char*, size_t refs = 0);
       protected:
        ~time_get_byname();          //  virtual
       };
     }</pre>
<p>&nbsp; Change section 22.2.5.4 (lib.locale.time.put.byname) to become:</p>
<pre>     namespace std {
       template &lt;class charT, class OutputIterator = ostreambuf_iterator&lt;charT&gt; &gt;
       class time_put_byname : public time_put&lt;charT, OutputIterator&gt;
       {
       public:
         typedef charT          char_type;
         typedef OutputIterator iter_type;</pre>
<pre>         explicit time_put_byname(const char*, size_t refs = 0);
       protected:
        ~time_put_byname();          //  virtual
       };
     }"</pre>
<p>&nbsp; Change section 22.2.6.4 (lib.locale.moneypunct.byname) to become:</p>
<pre>     namespace std {
       template &lt;class charT, bool Intl = false&gt;
       class moneypunct_byname : public moneypunct&lt;charT, Intl&gt; {
       public:
         typedef money_base::pattern pattern;
         typedef basic_string&lt;charT&gt; string_type;</pre>
<pre>         explicit moneypunct_byname(const char*, size_t refs = 0);
       protected:
        ~moneypunct_byname();        //  virtual
       };
     }</pre>
<p>&nbsp; Change section 22.2.7.2 (lib.locale.messages.byname) to become:</p>
<pre>     namespace std {
       template &lt;class charT&gt;
       class messages_byname : public messages&lt;charT&gt; {
       public:
         typedef messages_base::catalog catalog;
         typedef basic_string&lt;charT&gt;    string_type;</pre>
<pre>         explicit messages_byname(const char*, size_t refs = 0);
       protected:
        ~messages_byname();          //  virtual
       };
     }</pre>
<p>Remove section 22.2.1.4 <a href="lib-locales.html#lib.locale.ctype.byname.special"> [lib.locale.ctype.byname.special]</a> completely (because in
this case only those members are defined to be virtual which are
defined to be virtual in 'ctype&lt;cT&gt;'.)</p>

<p><i>[Post-Tokyo: Dietmar K&uuml;hl submitted this issue at the request of
the LWG to solve the underlying problems raised by issue <a href="lwg-closed.html#138">138</a>.]</i></p>

<p><i>[Copenhagen: proposed resolution was revised slightly, to remove
three last virtual functions from <tt>messages_byname</tt>.]</i></p>

<hr>
<a name="229"><h3>229.&nbsp;Unqualified references of other library entities</h3></a><p><b>Section:</b>&nbsp;17.4.1.1 <a href="lib-intro.html#lib.contents"> [lib.contents]</a>&nbsp; <b>Status:</b>&nbsp;<a href="lwg-active.html#WP">WP</a>&nbsp; <b>Submitter:</b>&nbsp;Steve Clamage&nbsp; <b>Date:</b>&nbsp;19 Apr 2000</p>
<p>Throughout the library chapters, the descriptions of library entities refer
to other library entities without necessarily qualifying the names.</p>

<p>For example, section 25.2.2 "Swap" describes the effect of
swap_ranges in terms of the unqualified name "swap". This section
could reasonably be interpreted to mean that the library must be implemented so
as to do a lookup of the unqualified name "swap", allowing users to
override any ::std::swap function when Koenig lookup applies.</p>

<p>Although it would have been best to use explicit qualification with
"::std::" throughout, too many lines in the standard would have to be
adjusted to make that change in a Technical Corrigendum.</p>

<p>Issue <a href="lwg-defects.html#182">182</a>, which addresses qualification of
<tt>size_t</tt>, is a special case of this.
</p>
<p><b>Proposed resolution:</b></p>
<p>To section 17.4.1.1 "Library contents" Add the following paragraph:</p>
<blockquote>
  <p>Whenever a name x defined in the standard library is mentioned, the name x
  is assumed to be fully qualified as ::std::x, unless explicitly described
  otherwise. For example, if the Effects section for library function F is
  described as calling library function G, the function ::std::G is meant.</p>
</blockquote>

<p><i>[Post-Tokyo: Steve Clamage submitted this issue at the request of
the LWG to solve a problem in the standard itself similar to the
problem within implementations of library identified by issue <a href="lwg-defects.html#225">225</a>.  Any resolution of issue <a href="lwg-defects.html#225">225</a> should be
coordinated with the resolution of this issue.]</i></p>

<p><i>[post-Toronto: Howard is undecided about whether it is
appropriate for all standard library function names referred to in
other standard library functions to be explicitly qualified by
<tt>std</tt>: it is common advice that users should define global
functions that operate on their class in the same namespace as the 
class, and this requires argument-dependent lookup if those functions
are intended to be called by library code.  Several LWG members are
concerned that valarray appears to require argument-dependent lookup,
but that the wording may not be clear enough to fall under
"unless explicitly described otherwise".]</i></p>

<p><i>[Cura&ccedil;ao: An LWG-subgroup spent an afternoon working on issues
225, 226, and 229.  Their conclusion was that the issues should be
separated into an LWG portion (Howard's paper, N1387=02-0045), and a
EWG portion (Dave will write a proposal). The LWG and EWG had
(separate) discussions of this plan the next day.  This paper resolves
issues 225 and 226.  In light of that resolution, the proposed
resolution for the current issue makes sense.]</i></p>

<hr>
<a name="230"><h3>230.&nbsp;Assignable specified without also specifying CopyConstructible</h3></a><p><b>Section:</b>&nbsp;17 <a href="lib-intro.html#lib.library"> [lib.library]</a>&nbsp; <b>Status:</b>&nbsp;<a href="lwg-active.html#WP">WP</a>&nbsp; <b>Submitter:</b>&nbsp;Beman Dawes&nbsp; <b>Date:</b>&nbsp;26 Apr 2000</p>
<p>Issue <a href="lwg-defects.html#227">227</a> identified an instance (std::swap) where
Assignable was specified without also specifying
CopyConstructible. The LWG asked that the standard be searched to
determine if the same defect existed elsewhere.</p>

<p>There are a number of places (see proposed resolution below) where
Assignable is specified without also specifying
CopyConstructible. There are also several cases where both are
specified. For example, 26.4.1 <a href="lib-numerics.html#lib.accumulate"> [lib.accumulate]</a>.</p>
<p><b>Proposed resolution:</b></p>
<p>In  23.1 <a href="lib-containers.html#lib.container.requirements"> [lib.container.requirements]</a> table 65 for value_type:
change "T is Assignable" to "T is CopyConstructible and
Assignable"
</p>

<p>In 23.1.2 <a href="lib-containers.html#lib.associative.reqmts"> [lib.associative.reqmts]</a> table 69 X::key_type; change
"Key is Assignable" to "Key is
CopyConstructible and Assignable"<br>
</p>

<p>In 24.1.2 <a href="lib-iterators.html#lib.output.iterators"> [lib.output.iterators]</a> paragraph 1, change:
</p>
<blockquote>
<p> A class or a built-in type X satisfies the requirements of an
output iterator if X is an Assignable type (23.1) and also the
following expressions are valid, as shown in Table 73:
</p>
</blockquote>
<p>to:
</p>
<blockquote>
<p> A class or a built-in type X satisfies the requirements of an
output iterator if X is a CopyConstructible (20.1.3) and Assignable
type (23.1) and also the following expressions are valid, as shown in
Table 73:
</p>
</blockquote>

<p><i>[Post-Tokyo: Beman Dawes submitted this issue at the request of
the LWG.  He asks that the 25.2.4 <a href="lib-algorithms.html#lib.alg.replace"> [lib.alg.replace]</a> and 25.2.5 <a href="lib-algorithms.html#lib.alg.fill"> [lib.alg.fill]</a> changes be studied carefully, as it is not clear that
CopyConstructible is really a requirement and may be
overspecification.]</i></p>

<p><i>[Portions of the resolution for issue 230 have been superceded by
the resolution of issue <a href="lwg-defects.html#276">276</a>.]</i></p>

<p><b>Rationale:</b></p>
<p>The original proposed resolution also included changes to input
iterator, fill, and replace.  The LWG believes that those changes are
not necessary.  The LWG considered some blanket statement, where an
Assignable type was also required to be Copy Constructible, but
decided against this because fill and replace really don't require the
Copy Constructible property.</p>
<hr>
<a name="231"><h3>231.&nbsp;Precision in iostream?</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#WP">WP</a>&nbsp; <b>Submitter:</b>&nbsp;James Kanze, Stephen Clamage&nbsp; <b>Date:</b>&nbsp; 25 Apr 2000</p>
<p>What is the following program supposed to output?</p>
<pre>#include &lt;iostream&gt;

    int
    main()
    {
        std::cout.setf( std::ios::scientific , std::ios::floatfield ) ;
        std::cout.precision( 0 ) ;
        std::cout &lt;&lt; 1.00 &lt;&lt; '\n' ;
        return 0 ;
    }</pre>
<p>From my C experience, I would expect "1e+00"; this is what 
<tt>printf("%.0e" , 1.00 );</tt> does. G++ outputs 
"1.000000e+00".</p>

<p>The only indication I can find in the standard is 22.2.2.2.2/11,
where it says "For conversion from a floating-point type, if
(flags &amp; fixed) != 0 or if str.precision() &gt; 0, then
str.precision() is specified in the conversion specification."
This is an obvious error, however, fixed is not a mask for a field,
but a value that a multi-bit field may take -- the results of and'ing
fmtflags with ios::fixed are not defined, at least not if
ios::scientific has been set. G++'s behavior corresponds to what might
happen if you do use (flags &amp; fixed) != 0 with a typical
implementation (floatfield == 3 &lt;&lt; something, fixed == 1
&lt;&lt; something, and scientific == 2 &lt;&lt; something).</p>

<p>Presumably, the intent is either (flags &amp; floatfield) != 0, or
(flags &amp; floatfield) == fixed; the first gives something more or
less like the effect of precision in a printf floating point
conversion. Only more or less, of course. In order to implement printf
formatting correctly, you must know whether the precision was
explicitly set or not. Say by initializing it to -1, instead of 6, and
stating that for floating point conversions, if precision &lt; -1, 6
will be used, for fixed point, if precision &lt; -1, 1 will be used,
etc. Plus, of course, if precision == 0 and flags &amp; floatfield ==
0, 1 should be = used. But it probably isn't necessary to emulate all
of the anomalies of printf:-).</p>
<p><b>Proposed resolution:</b></p>
<p>
Replace 22.2.2.2.2 <a href="lib-locales.html#lib.facet.num.put.virtuals"> [lib.facet.num.put.virtuals]</a>, paragraph 11, with the following 
sentence:
</p>
<blockquote>
For conversion from a floating-point type,
<tt><i>str</i>.precision()</tt> is specified in the conversion
specification.
</blockquote>
<p><b>Rationale:</b></p>
<p>The floatfield determines whether numbers are formatted as if
with %f, %e, or %g.  If the <tt>fixed</tt> bit is set, it's %f,
if <tt>scientific</tt> it's %e, and if both bits are set, or 
neither, it's %g.</p>
<p>Turning to the C standard, a precision of 0 is meaningful
for %f and %e.  For %g, precision 0 is taken to be the same as 
precision 1.</p>
<p>The proposed resolution has the effect that if neither
<tt>fixed</tt> nor <tt>scientific</tt> is set we'll be
specifying a precision of 0, which will be internally
turned into 1.  There's no need to call it out as a special
case.</p>
<p>The output of the above program will be "1e+00".</p>

<p><i>[Post-Cura&ccedil;ao: Howard provided improved wording covering the case
where precision is 0 and mode is %g.]</i></p>

<hr>
<a name="232"><h3>232.&nbsp;"depends" poorly defined in 17.4.3.1</h3></a><p><b>Section:</b>&nbsp;17.4.3.1 <a href="lib-intro.html#lib.reserved.names"> [lib.reserved.names]</a>&nbsp; <b>Status:</b>&nbsp;<a href="lwg-active.html#WP">WP</a>&nbsp; <b>Submitter:</b>&nbsp;Peter Dimov&nbsp; <b>Date:</b>&nbsp;18 Apr 2000</p>
<p>17.4.3.1/1 uses the term "depends" to limit the set of allowed
specializations of standard templates to those that "depend on a
user-defined name of external linkage."</p>
<p>This term, however, is not adequately defined, making it possible to
construct a specialization that is, I believe, technically legal according to
17.4.3.1/1, but that specializes a standard template for a built-in type such as
'int'.</p>
<p>The following code demonstrates the problem:</p>
<blockquote>
  <pre>#include &lt;algorithm&gt;</pre>
  <pre>template&lt;class T&gt; struct X
{
 typedef T type;
};</pre>
  <pre>namespace std
{
 template&lt;&gt; void swap(::X&lt;int&gt;::type&amp; i, ::X&lt;int&gt;::type&amp; j);
}</pre>
</blockquote>
<p><b>Proposed resolution:</b></p>
<p>Change "user-defined name" to "user-defined
type".</p>
<p><b>Rationale:</b></p>
<p>This terminology is used in section 2.5.2 and 4.1.1 of <i>The C++
Programming Language</i>.  It disallows the example in the issue,
since the underlying type itself is not user-defined.  The only
possible problem I can see is for non-type templates, but there's no
possible way for a user to come up with a specialization for bitset,
for example, that might not have already been specialized by the
implementor?</p>

<p><i>[Toronto: this may be related to issue <a href="lwg-defects.html#120">120</a>.]</i></p>

<p><i>[post-Toronto: Judy provided the above proposed resolution and
rationale.]</i></p>
<hr>
<a name="234"><h3>234.&nbsp;Typos in allocator definition</h3></a><p><b>Section:</b>&nbsp;20.4.1.1 <a href="lib-utilities.html#lib.allocator.members"> [lib.allocator.members]</a>&nbsp; <b>Status:</b>&nbsp;<a href="lwg-active.html#WP">WP</a>&nbsp; <b>Submitter:</b>&nbsp;Dietmar K&uuml;hl&nbsp; <b>Date:</b>&nbsp;24 Apr 2000</p>
<p>In paragraphs 12 and 13 the effects of <tt>construct()</tt> and
<tt>destruct()</tt> are described as returns but the functions actually
return <tt>void</tt>.</p>
<p><b>Proposed resolution:</b></p>
<p>Substitute "Returns" by "Effect".</p>
<hr>
<a name="235"><h3>235.&nbsp;No specification of default ctor for reverse_iterator</h3></a><p><b>Section:</b>&nbsp;24.4.1.1 <a href="lib-iterators.html#lib.reverse.iterator"> [lib.reverse.iterator]</a>&nbsp; <b>Status:</b>&nbsp;<a href="lwg-active.html#WP">WP</a>&nbsp; <b>Submitter:</b>&nbsp;Dietmar K&uuml;hl&nbsp; <b>Date:</b>&nbsp;24 Apr 2000</p>
<p>The declaration of <tt>reverse_iterator</tt> lists a default
constructor.  However, no specification is given what this constructor
should do.</p>
<p><b>Proposed resolution:</b></p>
  <p>In section 24.4.1.3.1 <a href="lib-iterators.html#lib.reverse.iter.cons"> [lib.reverse.iter.cons]</a> add the following
  paragraph:</p>
      <blockquote>
      <p><tt>reverse_iterator()</tt></p>

      <p>Default initializes <tt>current</tt>. Iterator operations
      applied to the resulting iterator have defined behavior if and
      only if the corresponding operations are defined on a default
      constructed iterator of type <tt>Iterator</tt>.</p>
      </blockquote>
  <p><i>[pre-Copenhagen: Dietmar provide wording for proposed
  resolution.]</i></p>
<hr>
<a name="237"><h3>237.&nbsp;Undefined expression in complexity specification</h3></a><p><b>Section:</b>&nbsp;23.2.2.1 <a href="lib-containers.html#lib.list.cons"> [lib.list.cons]</a>&nbsp; <b>Status:</b>&nbsp;<a href="lwg-active.html#WP">WP</a>&nbsp; <b>Submitter:</b>&nbsp;Dietmar K&uuml;hl&nbsp; <b>Date:</b>&nbsp;24 Apr 2000</p>
<p>The complexity specification in paragraph 6 says that the complexity
is linear in <tt>first - last</tt>. Even if <tt>operator-()</tt> is
defined on iterators this term is in general undefined because it
would have to be <tt>last - first</tt>.</p>
<p><b>Proposed resolution:</b></p>
  <p>Change paragraph 6 from</p>
     <blockquote>Linear in <i>first - last</i>.</blockquote>
  <p>to become</p>
     <blockquote>Linear in <i>distance(first, last)</i>.</blockquote>
<hr>
<a name="238"><h3>238.&nbsp;Contradictory results of stringbuf initialization.</h3></a><p><b>Section:</b>&nbsp;27.7.1.1 <a href="lib-iostreams.html#lib.stringbuf.cons"> [lib.stringbuf.cons]</a>&nbsp; <b>Status:</b>&nbsp;<a href="lwg-active.html#WP">WP</a>&nbsp; <b>Submitter:</b>&nbsp;Dietmar K&uuml;hl&nbsp; <b>Date:</b>&nbsp;11 May 2000</p>
<p>In 27.7.1.1 paragraph 4 the results of calling the constructor of
'basic_stringbuf' are said to be <tt>str() == str</tt>. This is fine
that far but consider this code:</p>

<pre>
  std::basic_stringbuf&lt;char&gt; sbuf("hello, world", std::ios_base::openmode(0));
  std::cout &lt;&lt; "'" &lt;&lt; sbuf.str() &lt;&lt; "'\n";
</pre>

<p>Paragraph 3 of 27.7.1.1 basically says that in this case neither
the output sequence nor the input sequence is initialized and
paragraph 2 of 27.7.1.2 basically says that <tt>str()</tt> either
returns the input or the output sequence. None of them is initialized,
ie. both are empty, in which case the return from <tt>str()</tt> is
defined to be <tt>basic_string&lt;cT&gt;()</tt>.</p>

<p>However, probably only test cases in some testsuites will detect this
"problem"...</p>
<p><b>Proposed resolution:</b></p>
<p>Remove 27.7.1.1 paragraph 4.</p>
<p><b>Rationale:</b></p>
<p>We could fix 27.7.1.1 paragraph 4, but there would be no point.  If
we fixed it, it would say just the same thing as text that's already
in the standard.</p>
<hr>
<a name="239"><h3>239.&nbsp;Complexity of unique() and/or unique_copy incorrect</h3></a><p><b>Section:</b>&nbsp;25.2.8 <a href="lib-algorithms.html#lib.alg.unique"> [lib.alg.unique]</a>&nbsp; <b>Status:</b>&nbsp;<a href="lwg-active.html#WP">WP</a>&nbsp; <b>Submitter:</b>&nbsp;Angelika Langer&nbsp; <b>Date:</b>&nbsp;May 15 2000</p>
<p>The complexity of unique and unique_copy are inconsistent with each
other and inconsistent with the implementations.&nbsp; The standard
specifies:</p>

<p>for unique():</p>

<blockquote>-3- Complexity: If the range (last - first) is not empty, exactly
(last - first) - 1 applications of the corresponding predicate, otherwise
no applications of the predicate.</blockquote>

<p>for unique_copy():</p>

<blockquote>-7- Complexity: Exactly last - first applications of the corresponding
predicate.</blockquote>

<p>
The implementations do it the other way round: unique() applies the
predicate last-first times and unique_copy() applies it last-first-1
times.</p>

<p>As both algorithms use the predicate for pair-wise comparison of
sequence elements I don't see a justification for unique_copy()
applying the predicate last-first times, especially since it is not
specified to which pair in the sequence the predicate is applied
twice.</p>
<p><b>Proposed resolution:</b></p>
<p>Change both complexity sections in 25.2.8 <a href="lib-algorithms.html#lib.alg.unique"> [lib.alg.unique]</a> to:</p>

<blockquote>Complexity: For nonempty ranges, exactly last - first - 1
applications of the corresponding predicate.</blockquote>

<hr>
<a name="240"><h3>240.&nbsp;Complexity of adjacent_find() is meaningless</h3></a><p><b>Section:</b>&nbsp;25.1.5 <a href="lib-algorithms.html#lib.alg.adjacent.find"> [lib.alg.adjacent.find]</a>&nbsp; <b>Status:</b>&nbsp;<a href="lwg-active.html#WP">WP</a>&nbsp; <b>Submitter:</b>&nbsp;Angelika Langer&nbsp; <b>Date:</b>&nbsp;May 15 2000</p>
<p>The complexity section of adjacent_find is defective:</p>

<blockquote>
<pre>
template &lt;class ForwardIterator&gt;
ForwardIterator adjacent_find(ForwardIterator first, ForwardIterator last
                              BinaryPredicate pred);
</pre>

<p>-1- Returns: The first iterator i such that both i and i + 1 are in
the range [first, last) for which the following corresponding
conditions hold: *i == *(i + 1), pred(*i, *(i + 1)) != false. Returns
last if no such iterator is found.</p>

<p>-2- Complexity: Exactly find(first, last, value) - first applications
of the corresponding predicate.
</p>
</blockquote>

<p>In the Complexity section, it is not defined what "value"
is supposed to mean. My best guess is that "value" means an
object for which one of the conditions pred(*i,value) or
pred(value,*i) is true, where i is the iterator defined in the Returns
section. However, the value type of the input sequence need not be
equality-comparable and for this reason the term find(first, last,
value) - first is meaningless.</p>

<p>A term such as find_if(first, last, bind2nd(pred,*i)) - first or
find_if(first, last, bind1st(pred,*i)) - first might come closer to
the intended specification.  Binders can only be applied to function
objects that have the function call operator declared const, which is
not required of predicates because they can have non-const data
members. For this reason, a specification using a binder could only be
an "as-if" specification.</p>
<p><b>Proposed resolution:</b></p>
<p>Change the complexity section in 25.1.5 <a href="lib-algorithms.html#lib.alg.adjacent.find"> [lib.alg.adjacent.find]</a> to:</p>
<blockquote>
For a nonempty range, exactly <tt>min((<i>i</i> - <i>first</i>) + 1,
(<i>last</i> - <i>first</i>) - 1)</tt> applications of the
corresponding predicate, where <i>i</i> is <tt>adjacent_find</tt>'s
return value.
</blockquote>

<p><i>[Copenhagen: the original resolution specified an upper
bound.  The LWG preferred an exact count.]</i></p>

<hr>
<a name="241"><h3>241.&nbsp;Does unique_copy() require CopyConstructible and Assignable?</h3></a><p><b>Section:</b>&nbsp;25.2.8 <a href="lib-algorithms.html#lib.alg.unique"> [lib.alg.unique]</a>&nbsp; <b>Status:</b>&nbsp;<a href="lwg-active.html#WP">WP</a>&nbsp; <b>Submitter:</b>&nbsp;Angelika Langer&nbsp; <b>Date:</b>&nbsp;May 15 2000</p>

<p>Some popular implementations of unique_copy() create temporary
copies of values in the input sequence, at least if the input iterator
is a pointer.  Such an implementation is built on the assumption that
the value type is CopyConstructible and Assignable.</p>

<p>It is common practice in the standard that algorithms explicitly
specify any additional requirements that they impose on any of the
types used by the algorithm. An example of an algorithm that creates
temporary copies and correctly specifies the additional requirements
is accumulate(), 26.4.1 <a href="lib-numerics.html#lib.accumulate"> [lib.accumulate]</a>.</p>

<p>Since the specifications of unique() and unique_copy() do not
require CopyConstructible and Assignable of the InputIterator's value
type the above mentioned implementations are not standard-compliant. I
cannot judge whether this is a defect in the standard or a defect in
the implementations.</p>
<p><b>Proposed resolution:</b></p>
<p>In 25.2.8 change:</p>

<blockquote>
-4- Requires: The ranges [first, last) and [result, result+(last-first))
shall not overlap.
</blockquote>

<p>to:</p>

<blockquote>
  <p>-4- Requires: The ranges [first, last) and [result,
  result+(last-first)) shall not overlap. The expression *result =
  *first must be valid. If neither InputIterator nor OutputIterator
  meets the requirements of forward iterator then the value type of
  InputIterator must be copy constructible. Otherwise copy
  constructible is not required. </p>
</blockquote>

<p><i>[Redmond: the original proposed resolution didn't impose an
explicit requirement that the iterator's value type must be copy
constructible, on the grounds that an input iterator's value type must
always be copy constructible.  Not everyone in the LWG thought that
this requirement was clear from table 72.  It has been suggested that
it might be possible to implement <tt>unique_copy</tt> without
requiring assignability, although current implementations do impose
that requirement.  Howard provided new wording.]</i></p>

<p><i>[
Cura&ccedil;ao: The LWG changed the PR editorially to specify
"neither...nor...meet..." as clearer than
"both...and...do not meet...". Change believed to be so
minor as not to require re-review.
]</i></p>

<hr>
<a name="242"><h3>242.&nbsp;Side effects of function objects</h3></a><p><b>Section:</b>&nbsp;25.2.3 <a href="lib-algorithms.html#lib.alg.transform"> [lib.alg.transform]</a>, 26.4 <a href="lib-numerics.html#lib.numeric.ops"> [lib.numeric.ops]</a>&nbsp; <b>Status:</b>&nbsp;<a href="lwg-active.html#WP">WP</a>&nbsp; <b>Submitter:</b>&nbsp;Angelika Langer&nbsp; <b>Date:</b>&nbsp;May 15 2000</p>
<p>The algorithms transform(), accumulate(), inner_product(),
partial_sum(), and adjacent_difference() require that the function
object supplied to them shall not have any side effects.</p>

<p>The standard defines a side effect in 1.9 <a href="intro.html#intro.execution"> [intro.execution]</a> as:</p>
<blockquote>-7- Accessing an object designated by a volatile lvalue (basic.lval),
modifying an object, calling a library I/O function, or calling a function
that does any of those operations are all side effects, which are changes
in the state of the execution environment.</blockquote>

<p>As a consequence, the function call operator of a function object supplied
to any of the algorithms listed above cannot modify data members, cannot
invoke any function that has a side effect, and cannot even create and
modify temporary objects.&nbsp; It is difficult to imagine a function object
that is still useful under these severe limitations. For instance, any
non-trivial transformator supplied to transform() might involve creation
and modification of temporaries, which is prohibited according to the current
wording of the standard.</p>

<p>On the other hand, popular implementations of these algorithms exhibit
uniform and predictable behavior when invoked with a side-effect-producing
function objects. It looks like the strong requirement is not needed for
efficient implementation of these algorithms.</p>

<p>The requirement of&nbsp; side-effect-free function objects could be
replaced by a more relaxed basic requirement (which would hold for all
function objects supplied to any algorithm in the standard library):</p>
<blockquote>A function objects supplied to an algorithm shall not invalidate
any iterator or sequence that is used by the algorithm. Invalidation of
the sequence includes destruction of the sorting order if the algorithm
relies on the sorting order (see section 25.3 - Sorting and related operations
[lib.alg.sorting]).</blockquote>

<p>I can't judge whether it is intended that the function objects supplied
to transform(), accumulate(), inner_product(), partial_sum(), or adjacent_difference()
shall not modify sequence elements through dereferenced iterators.</p>

<p>It is debatable whether this issue is a defect or a change request.
Since the consequences for user-supplied function objects are drastic and
limit the usefulness of the algorithms significantly I would consider it
a defect.</p>
<p><b>Proposed resolution:</b></p>

<p><i>Things to notice about these changes:</i></p>

<ol>
<li> <i>The fully-closed ("[]" as opposed to half-closed "[)" ranges
     are intentional. we want to prevent side-effects from
     invalidating the end iterators.</i>
</li>

<li> <i>That has the unintentional side-effect of prohibiting
     modification of the end element as a side-effect. This could
     conceivably be significant in some cases.</i>
</li>

<li> <i>The wording also prevents side-effects from modifying elements
     of the output sequence. I can't imagine why anyone would want
     to do this, but it is arguably a restriction that implementors
     don't need to place on users.</i>
</li>

<li> <i>Lifting the restrictions imposed in #2 and #3 above is possible
     and simple, but would require more verbiage.</i>
</li>
</ol>

<p>Change 25.2.3/2 from:</p>

<blockquote>
   -2- Requires: op and binary_op shall not have any side effects.
</blockquote>

<p>to:</p>

<blockquote>
  -2- Requires: in the ranges [first1, last1], [first2, first2 +
  (last1 - first1)] and [result, result + (last1- first1)], op and
  binary_op shall neither modify elements nor invalidate iterators or
  subranges.
  [Footnote: The use of fully closed ranges is intentional --end footnote]
</blockquote>


<p>Change 25.2.3/2 from:</p>

<blockquote>
   -2- Requires: op and binary_op shall not have any side effects. 
</blockquote>

<p>to:</p>

<blockquote>
  -2- Requires: op and binary_op shall not invalidate iterators or
   subranges, or modify elements in the ranges [first1, last1],
   [first2, first2 + (last1 - first1)], and [result, result + (last1
   - first1)].
  [Footnote: The use of fully closed ranges is intentional --end footnote]
</blockquote>


<p>Change 26.4.1/2 from:</p>

<blockquote>
  -2- Requires: T must meet the requirements of CopyConstructible
   (lib.copyconstructible) and Assignable (lib.container.requirements)
   types. binary_op shall not cause side effects.
</blockquote>

<p>to:</p>

<blockquote>
  -2- Requires: T must meet the requirements of CopyConstructible
   (lib.copyconstructible) and Assignable
   (lib.container.requirements) types. In the range [first, last],
   binary_op shall neither modify elements nor invalidate iterators
   or subranges.
  [Footnote: The use of a fully closed range is intentional --end footnote]
</blockquote>

<p>Change 26.4.2/2 from:</p>

<blockquote>
  -2- Requires: T must meet the requirements of CopyConstructible
   (lib.copyconstructible) and Assignable (lib.container.requirements)
   types. binary_op1 and binary_op2 shall not cause side effects.
</blockquote>

<p>to:</p>

<blockquote>
  -2- Requires: T must meet the requirements of CopyConstructible
   (lib.copyconstructible) and Assignable (lib.container.requirements)
   types. In the ranges [first, last] and [first2, first2 + (last -
   first)], binary_op1 and binary_op2 shall neither modify elements
   nor invalidate iterators or subranges.
  [Footnote: The use of fully closed ranges is intentional --end footnote]
</blockquote>


<p>Change 26.4.3/4 from:</p>

<blockquote>
  -4- Requires: binary_op is expected not to have any side effects.
</blockquote>

<p>to:</p>

<blockquote>
  -4- Requires: In the ranges [first, last] and [result, result +
   (last - first)], binary_op shall neither modify elements nor
   invalidate iterators or subranges.
  [Footnote: The use of fully closed ranges is intentional --end footnote]
</blockquote>

<p>Change 26.4.4/2 from:</p>

<blockquote>
  -2- Requires: binary_op shall not have any side effects.
</blockquote>

<p>to:</p>

<blockquote>
  -2- Requires: In the ranges [first, last] and [result, result +
   (last - first)], binary_op shall neither modify elements nor
   invalidate iterators or subranges.
  [Footnote: The use of fully closed ranges is intentional --end footnote]
</blockquote>

<p><i>[Toronto: Dave Abrahams supplied wording.]</i></p>

<p><i>[Copenhagen: Proposed resolution was modified slightly. Matt
added footnotes pointing out that the use of closed ranges was
intentional.]</i></p>

<hr>
<a name="243"><h3>243.&nbsp;<tt>get</tt> and <tt>getline</tt> when sentry reports failure</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#WP">WP</a>&nbsp; <b>Submitter:</b>&nbsp;Martin Sebor&nbsp; <b>Date:</b>&nbsp;May 15 2000</p>
<p>basic_istream&lt;&gt;::get(), and basic_istream&lt;&gt;::getline(),
are unclear with respect to the behavior and side-effects of the named
functions in case of an error.</p>

<p>27.6.1.3, p1 states that "... If the sentry object returns
true, when converted to a value of type bool, the function endeavors
to obtain the requested input..." It is not clear from this (or
the rest of the paragraph) what precisely the behavior should be when
the sentry ctor exits by throwing an exception or when the sentry
object returns false.  In particular, what is the number of characters
extracted that gcount() returns supposed to be?</p>

<p>27.6.1.3 p8 and p19 say about the effects of get() and getline():
"...  In any case, it then stores a null character (using
charT()) into the next successive location of the array." Is not
clear whether this sentence applies if either of the conditions above
holds (i.e., when sentry fails).</p>
<p><b>Proposed resolution:</b></p>
<p>Add to 27.6.1.3, p1 after the sentence</p>

<blockquote>
"... If the sentry object returns true, when converted to a value of
type bool, the function endeavors to obtain the requested input."
</blockquote>

<p>the following</p>


<blockquote>
"Otherwise, if the sentry constructor exits by throwing an exception or
if the sentry object returns false, when converted to a value of type
bool, the function returns without attempting to obtain any input. In
either case the number of extracted characters is set to 0; unformatted
input functions taking a character array of non-zero size as an argument
shall also store a null character (using charT()) in the first location
of the array."
</blockquote>
<p><b>Rationale:</b></p>
<p>Although the general philosophy of the input functions is that the
argument should not be modified upon failure, <tt>getline</tt>
historically added a terminating null unconditionally.  Most
implementations still do that.  Earlier versions of the draft standard
had language that made this an unambiguous requirement; those words
were moved to a place where their context made them less clear.  See
Jerry Schwarz's message c++std-lib-7618.</p>
<hr>
<a name="248"><h3>248.&nbsp;time_get fails to set eofbit</h3></a><p><b>Section:</b>&nbsp;22.2.5 <a href="lib-locales.html#lib.category.time"> [lib.category.time]</a>&nbsp; <b>Status:</b>&nbsp;<a href="lwg-active.html#WP">WP</a>&nbsp; <b>Submitter:</b>&nbsp;Martin Sebor&nbsp; <b>Date:</b>&nbsp;22 June 2000</p>
<p>There is no requirement that any of time_get member functions set
ios::eofbit when they reach the end iterator while parsing their input.
Since members of both the num_get and money_get facets are required to
do so (22.2.2.1.2, and 22.2.6.1.2, respectively), time_get members
should follow the same requirement for consistency.</p>
<p><b>Proposed resolution:</b></p>
<p>Add paragraph 2 to section 22.2.5.1 with the following text:</p>

<blockquote>
If the end iterator is reached during parsing by any of the get()
member functions, the member sets ios_base::eofbit in err.
</blockquote>
<p><b>Rationale:</b></p>
<p>Two alternative resolutions were proposed.  The LWG chose this one
because it was more consistent with the way eof is described for other
input facets.</p>
<hr>
<a name="250"><h3>250.&nbsp;splicing invalidates iterators</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#WP">WP</a>&nbsp; <b>Submitter:</b>&nbsp;Brian Parker &nbsp; <b>Date:</b>&nbsp;14 Jul 2000</p>
<p>
Section 23.2.2.4 [lib.list.ops] states that
</p>
<pre>
  void splice(iterator position, list&lt;T, Allocator&gt;&amp; x);
</pre>
<p>
<i>invalidates</i> all iterators and references to list <tt>x</tt>.
</p>

<p>
This is unnecessary and defeats an important feature of splice. In
fact, the SGI STL guarantees that iterators to <tt>x</tt> remain valid
after <tt>splice</tt>.
</p>
<p><b>Proposed resolution:</b></p>

<p>Add a footnote to 23.2.2.4 <a href="lib-containers.html#lib.list.ops"> [lib.list.ops]</a>, paragraph 1:</p>
<blockquote>
[<i>Footnote:</i> As specified in 20.1.5 <a href="lib-utilities.html#lib.allocator.requirements"> [lib.allocator.requirements]</a>, paragraphs
4-5, the semantics described in this clause applies only to the case
where allocators compare equal.  --end footnote]
</blockquote>

<p>In 23.2.2.4 <a href="lib-containers.html#lib.list.ops"> [lib.list.ops]</a>, replace paragraph 4 with:</p>
<blockquote>
Effects: Inserts the contents of x before position and x becomes 
empty.  Pointers and references to the moved elements of x now refer to 
those same elements but as members of *this.  Iterators referring to the 
moved elements will continue to refer to their elements, but they now 
behave as iterators into *this, not into x.
</blockquote>

<p>In 23.2.2.4 <a href="lib-containers.html#lib.list.ops"> [lib.list.ops]</a>, replace paragraph 7 with:</p>
<blockquote>
Effects: Inserts an element pointed to by i from list x before 
position and removes the element from x. The result is unchanged if 
position == i or position == ++i.  Pointers and references to *i continue 
to refer to this same element but as a member of *this.  Iterators to *i 
(including i itself) continue to refer to the same element, but now 
behave as iterators into *this, not into x.
</blockquote>

<p>In 23.2.2.4 <a href="lib-containers.html#lib.list.ops"> [lib.list.ops]</a>, replace paragraph 12 with:</p>
<blockquote>
Requires: [first, last) is a valid range in x. The result is 
undefined if position is an iterator in the range [first, last).  
Pointers and references to the moved elements of x now refer to those 
same elements but as members of *this.  Iterators referring to the moved 
elements will continue to refer to their elements, but they now behave as 
iterators into *this, not into x.
</blockquote>

<p><i>[pre-Copenhagen: Howard provided wording.]</i></p>
<p><b>Rationale:</b></p>
<p>The original proposed resolution said that iterators and references
would remain "valid".  The new proposed resolution clarifies what that
means.  Note that this only applies to the case of equal allocators.
From 20.1.5 <a href="lib-utilities.html#lib.allocator.requirements"> [lib.allocator.requirements]</a> paragraph 4, the behavior of list when
allocators compare nonequal is outside the scope of the standard.</p>
<hr>
<a name="251"><h3>251.&nbsp;basic_stringbuf missing allocator_type</h3></a><p><b>Section:</b>&nbsp;27.7.1 <a href="lib-iostreams.html#lib.stringbuf"> [lib.stringbuf]</a>&nbsp; <b>Status:</b>&nbsp;<a href="lwg-active.html#WP">WP</a>&nbsp; <b>Submitter:</b>&nbsp;Martin Sebor&nbsp; <b>Date:</b>&nbsp;28 Jul 2000</p>
<p>The synopsis for the template class <tt>basic_stringbuf</tt>
doesn't list a typedef for the template parameter
<tt>Allocator</tt>. This makes it impossible to determine the type of
the allocator at compile time. It's also inconsistent with all other
template classes in the library that do provide a typedef for the
<tt>Allocator</tt> parameter.</p>
<p><b>Proposed resolution:</b></p>
<p>Add to the synopses of the class templates basic_stringbuf (27.7.1),
basic_istringstream (27.7.2), basic_ostringstream (27.7.3), and 
basic_stringstream (27.7.4) the typedef:</p>
<pre>
  typedef Allocator allocator_type;
</pre>
<hr>
<a name="252"><h3>252.&nbsp;missing casts/C-style casts used in iostreams</h3></a><p><b>Section:</b>&nbsp;27.7 <a href="lib-iostreams.html#lib.string.streams"> [lib.string.streams]</a>&nbsp; <b>Status:</b>&nbsp;<a href="lwg-active.html#WP">WP</a>&nbsp; <b>Submitter:</b>&nbsp;Martin Sebor&nbsp; <b>Date:</b>&nbsp;28 Jul 2000</p>
<p>27.7.2.2, p1 uses a C-style cast rather than the more appropriate
const_cast&lt;&gt; in the Returns clause for basic_istringstream&lt;&gt;::rdbuf().
The same C-style cast is being used in 27.7.3.2, p1, D.7.2.2, p1, and
D.7.3.2, p1, and perhaps elsewhere. 27.7.6, p1 and D.7.2.2, p1 are missing
the cast altogether.</p>

<p>C-style casts have not been deprecated, so the first part of this
issue is stylistic rather than a matter of correctness.</p>
<p><b>Proposed resolution:</b></p>
<p>In 27.7.2.2, p1 replace </p>
<pre>  -1- Returns: (basic_stringbuf&lt;charT,traits,Allocator&gt;*)&amp;sb.</pre>

<p>with</p>
<pre>  -1- Returns: const_cast&lt;basic_stringbuf&lt;charT,traits,Allocator&gt;*&gt;(&amp;sb).</pre>


<p>In 27.7.3.2, p1 replace</p>
<pre>  -1- Returns: (basic_stringbuf&lt;charT,traits,Allocator&gt;*)&amp;sb.</pre>

<p>with</p>
<pre>  -1- Returns: const_cast&lt;basic_stringbuf&lt;charT,traits,Allocator&gt;*&gt;(&amp;sb).</pre>

<p>In 27.7.6, p1, replace</p>
<pre>  -1- Returns: &amp;sb</pre>

<p>with</p>
<pre>  -1- Returns: const_cast&lt;basic_stringbuf&lt;charT,traits,Allocator&gt;*&gt;(&amp;sb).</pre>

<p>In D.7.2.2, p1 replace</p>
<pre>  -2- Returns: &amp;sb. </pre>

<p>with</p>
<pre>  -2- Returns: const_cast&lt;strstreambuf*&gt;(&amp;sb).</pre>
<hr>
<a name="253"><h3>253.&nbsp;valarray helper functions are almost entirely useless</h3></a><p><b>Section:</b>&nbsp;26.3.2.1 <a href="lib-numerics.html#lib.valarray.cons"> [lib.valarray.cons]</a>, 26.3.2.2 <a href="lib-numerics.html#lib.valarray.assign"> [lib.valarray.assign]</a>&nbsp; <b>Status:</b>&nbsp;<a href="lwg-active.html#WP">WP</a>&nbsp; <b>Submitter:</b>&nbsp;Robert Klarer&nbsp; <b>Date:</b>&nbsp;31 Jul 2000</p>
<p>This discussion is adapted from message c++std-lib-7056 posted
November 11, 1999.  I don't think that anyone can reasonably claim
that the problem described below is NAD.</p>

<p>These valarray constructors can never be called:</p>

<pre>
   template &lt;class T&gt;
         valarray&lt;T&gt;::valarray(const slice_array&lt;T&gt; &amp;);
   template &lt;class T&gt;
         valarray&lt;T&gt;::valarray(const gslice_array&lt;T&gt; &amp;);
   template &lt;class T&gt;
         valarray&lt;T&gt;::valarray(const mask_array&lt;T&gt; &amp;);
   template &lt;class T&gt;
         valarray&lt;T&gt;::valarray(const indirect_array&lt;T&gt; &amp;);
</pre>

<p>Similarly, these valarray assignment operators cannot be
called:</p>

<pre>
     template &lt;class T&gt;
     valarray&lt;T&gt; valarray&lt;T&gt;::operator=(const slice_array&lt;T&gt; &amp;);
     template &lt;class T&gt;
     valarray&lt;T&gt; valarray&lt;T&gt;::operator=(const gslice_array&lt;T&gt; &amp;);
     template &lt;class T&gt;
     valarray&lt;T&gt; valarray&lt;T&gt;::operator=(const mask_array&lt;T&gt; &amp;);
     template &lt;class T&gt;
     valarray&lt;T&gt; valarray&lt;T&gt;::operator=(const indirect_array&lt;T&gt; &amp;);
</pre>

<p>Please consider the following example:</p>

<pre>
   #include &lt;valarray&gt;
   using namespace std;

   int main()
   {
       valarray&lt;double&gt; va1(12);
       valarray&lt;double&gt; va2(va1[slice(1,4,3)]); // line 1
   }
</pre>


<p>Since the valarray va1 is non-const, the result of the sub-expression
va1[slice(1,4,3)] at line 1 is an rvalue of type const
std::slice_array&lt;double&gt;.  This slice_array rvalue is then used to
construct va2.  The constructor that is used to construct va2 is
declared like this:</p>

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

<p>Notice the constructor's const reference parameter.  When the
constructor is called, a slice_array must be bound to this reference.
The rules for binding an rvalue to a const reference are in 8.5.3,
paragraph 5 (see also 13.3.3.1.4).  Specifically, paragraph 5
indicates that a second slice_array rvalue is constructed (in this
case copy-constructed) from the first one; it is this second rvalue
that is bound to the reference parameter.  Paragraph 5 also requires
that the constructor that is used for this purpose be callable,
regardless of whether the second rvalue is elided.  The
copy-constructor in this case is not callable, however, because it is
private.  Therefore, the compiler should report an error.</p>

<p>Since slice_arrays are always rvalues, the valarray constructor that has a
parameter of type const slice_array&lt;T&gt; &amp; can never be called.  The
same reasoning applies to the three other constructors and the four
assignment operators that are listed at the beginning of this post.
Furthermore, since these functions cannot be called, the valarray helper
classes are almost entirely useless.</p>
<p><b>Proposed resolution:</b></p>
<p>slice_array:</p>
<ul>
<li> Make the copy constructor and copy-assignment operator declarations
     public in the slice_array class template definition in 26.3.5 <a href="lib-numerics.html#lib.template.slice.array"> [lib.template.slice.array]</a> </li>
<li> remove paragraph 3 of 26.3.5 <a href="lib-numerics.html#lib.template.slice.array"> [lib.template.slice.array]</a>
</li>
<li> remove the copy constructor declaration from 26.3.5.1 <a href="lib-numerics.html#lib.cons.slice.arr"> [lib.cons.slice.arr]</a>
</li>
<li> change paragraph 1 of 26.3.5.1 <a href="lib-numerics.html#lib.cons.slice.arr"> [lib.cons.slice.arr]</a> to read "This constructor is declared
    to be private.  This constructor need not be defined."</li>
<li> remove the first sentence of paragraph 1 of 26.3.5.2 <a href="lib-numerics.html#lib.slice.arr.assign"> [lib.slice.arr.assign]</a>
</li>
<li> Change the first three words of the second sentence of paragraph 1 of
    26.3.5.2 <a href="lib-numerics.html#lib.slice.arr.assign"> [lib.slice.arr.assign]</a> to "These assignment operators have"</li>
</ul>

<p>gslice_array:</p>
<ul>
<li> Make the copy constructor and copy-assignment operator declarations
    public in the gslice_array class template definition in 26.3.7 <a href="lib-numerics.html#lib.template.gslice.array"> [lib.template.gslice.array]</a> </li>
<li> remove the note in paragraph 3 of 26.3.7 <a href="lib-numerics.html#lib.template.gslice.array"> [lib.template.gslice.array]</a>
</li>
<li> remove the copy constructor declaration from 26.3.7.1 <a href="lib-numerics.html#lib.gslice.array.cons"> [lib.gslice.array.cons]</a>
</li>
<li> change paragraph 1 of 26.3.7.1 <a href="lib-numerics.html#lib.gslice.array.cons"> [lib.gslice.array.cons]</a> to read "This constructor is declared
    to be private.  This constructor need not be defined."</li>
<li> remove the first sentence of paragraph 1 of 26.3.7.2 <a href="lib-numerics.html#lib.gslice.array.assign"> [lib.gslice.array.assign]</a>
</li>
<li> Change the first three words of the second sentence of paragraph 1 of
    26.3.7.2 <a href="lib-numerics.html#lib.gslice.array.assign"> [lib.gslice.array.assign]</a> to "These assignment operators have"</li>
</ul>

<p>mask_array:</p>
<ul>
<li> Make the copy constructor and copy-assignment operator declarations
    public in the mask_array class template definition in 26.3.8 <a href="lib-numerics.html#lib.template.mask.array"> [lib.template.mask.array]</a> </li>
<li> remove the note in paragraph 2 of 26.3.8 <a href="lib-numerics.html#lib.template.mask.array"> [lib.template.mask.array]</a>
</li>
<li> remove the copy constructor declaration from 26.3.8.1 <a href="lib-numerics.html#lib.mask.array.cons"> [lib.mask.array.cons]</a>
</li>
<li> change paragraph 1 of 26.3.8.1 <a href="lib-numerics.html#lib.mask.array.cons"> [lib.mask.array.cons]</a> to read "This constructor is declared
    to be private.  This constructor need not be defined."</li>
<li> remove the first sentence of paragraph 1 of 26.3.8.2 <a href="lib-numerics.html#lib.mask.array.assign"> [lib.mask.array.assign]</a>
</li>
<li> Change the first three words of the second sentence of paragraph 1 of
    26.3.8.2 <a href="lib-numerics.html#lib.mask.array.assign"> [lib.mask.array.assign]</a> to "These assignment operators have"</li>
</ul>

<p>indirect_array:</p>
<ul>
<li>Make the copy constructor and copy-assignment operator declarations
    public in the indirect_array class definition in 26.3.9 <a href="lib-numerics.html#lib.template.indirect.array"> [lib.template.indirect.array]</a>
</li>
<li> remove the note in paragraph 2 of 26.3.9 <a href="lib-numerics.html#lib.template.indirect.array"> [lib.template.indirect.array]</a>
</li>
<li> remove the copy constructor declaration from 26.3.9.1 <a href="lib-numerics.html#lib.indirect.array.cons"> [lib.indirect.array.cons]</a>
</li>
<li> change the descriptive text in 26.3.9.1 <a href="lib-numerics.html#lib.indirect.array.cons"> [lib.indirect.array.cons]</a> to read "This constructor is
    declared to be private.  This constructor need not be defined."</li>
<li> remove the first sentence of paragraph 1 of 26.3.9.2 <a href="lib-numerics.html#lib.indirect.array.assign"> [lib.indirect.array.assign]</a>
</li>
<li> Change the first three words of the second sentence of paragraph 1 of
    26.3.9.2 <a href="lib-numerics.html#lib.indirect.array.assign"> [lib.indirect.array.assign]</a> to "These assignment operators have"</li>
</ul>
<p><i>[Proposed resolution was modified in Santa Cruz: explicitly make
copy constructor and copy assignment operators public, instead of
removing them.]</i></p>
<p><b>Rationale:</b></p>
<p>Keeping the valarray constructors private is untenable.  Merely
making valarray a friend of the helper classes isn't good enough,
because access to the copy constructor is checked in the user's
environment.</p>

<p>Making the assignment operator public is not strictly necessary to
solve this problem.  A majority of the LWG <i>(straw poll: 13-4)</i>
believed we should make the assignment operators public, in addition
to the copy constructors, for reasons of symmetry and user
expectation.</p>
<hr>
<a name="256"><h3>256.&nbsp;typo in 27.4.4.2, p17: copy_event does not exist</h3></a><p><b>Section:</b>&nbsp;27.4.4.2 <a href="lib-iostreams.html#lib.basic.ios.members"> [lib.basic.ios.members]</a>&nbsp; <b>Status:</b>&nbsp;<a href="lwg-active.html#WP">WP</a>&nbsp; <b>Submitter:</b>&nbsp;Martin Sebor&nbsp; <b>Date:</b>&nbsp;21 Aug 2000</p>
<p>
27.4.4.2, p17 says
</p>

<blockquote>
-17- Before copying any parts of rhs, calls each registered callback
pair (fn,index) as (*fn)(erase_event,*this,index). After all parts but
exceptions() have been replaced, calls each callback pair that was
copied from rhs as (*fn)(copy_event,*this,index). 
</blockquote>

<p>
The name copy_event isn't defined anywhere. The intended name was
copyfmt_event.
</p>
<p><b>Proposed resolution:</b></p>
<p>Replace copy_event with copyfmt_event in the named paragraph.</p>
<hr>
<a name="259"><h3>259.&nbsp;<tt>basic_string::operator[]</tt> and const correctness</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#WP">WP</a>&nbsp; <b>Submitter:</b>&nbsp;Chris Newton &nbsp; <b>Date:</b>&nbsp;27 Aug 2000</p>
<p>
<i>Paraphrased from a message that Chris Newton posted to comp.std.c++:</i>
</p>

<p>
The standard's description of <tt>basic_string&lt;&gt;::operator[]</tt>
seems to violate const correctness.
</p>

<p>
The standard (21.3.4/1) says that "If <tt>pos &lt; size()</tt>,
returns <tt>data()[pos]</tt>." The types don't work.  The
return value of <tt>data()</tt> is <tt>const charT*</tt>, but
<tt>operator[]</tt> has a non-const version whose return type is <tt>reference</tt>.
</p>
<p><b>Proposed resolution:</b></p>
<p>
In section 21.3.4, paragraph 1, change
"<tt>data()[<i>pos</i>]</tt>" to "<tt>*(begin() +
<i>pos</i>)</tt>".
</p>
<hr>
<a name="260"><h3>260.&nbsp;Inconsistent return type of <tt>istream_iterator::operator++(int)</tt>
</h3></a><p><b>Section:</b>&nbsp;24.5.1.2 <a href="lib-iterators.html#lib.istream.iterator.ops"> [lib.istream.iterator.ops]</a>&nbsp; <b>Status:</b>&nbsp;<a href="lwg-active.html#WP">WP</a>&nbsp; <b>Submitter:</b>&nbsp;Martin Sebor&nbsp; <b>Date:</b>&nbsp;27 Aug 2000</p>
<p>The synopsis of istream_iterator::operator++(int) in 24.5.1 shows
it as returning the iterator by value. 24.5.1.2, p5 shows the same
operator as returning the iterator by reference. That's incorrect
given the Effects clause below (since a temporary is returned). The
`&amp;' is probably just a typo.</p>
<p><b>Proposed resolution:</b></p>
<p>Change the declaration in 24.5.1.2, p5 from</p>
 <pre>
 istream_iterator&lt;T,charT,traits,Distance&gt;&amp; operator++(int);
 </pre>
<p>to</p>
 <pre>
 istream_iterator&lt;T,charT,traits,Distance&gt; operator++(int);
 </pre>
<p>(that is, remove the `&amp;').</p>
<hr>
<a name="261"><h3>261.&nbsp;Missing description of <tt>istream_iterator::operator!=</tt>
</h3></a><p><b>Section:</b>&nbsp;24.5.1.2 <a href="lib-iterators.html#lib.istream.iterator.ops"> [lib.istream.iterator.ops]</a>&nbsp; <b>Status:</b>&nbsp;<a href="lwg-active.html#WP">WP</a>&nbsp; <b>Submitter:</b>&nbsp;Martin Sebor&nbsp; <b>Date:</b>&nbsp;27 Aug 2000</p>
<p>
24.5.1, p3 lists the synopsis for
</p>

<pre>
   template &lt;class T, class charT, class traits, class Distance&gt;
        bool operator!=(const istream_iterator&lt;T,charT,traits,Distance&gt;&amp; x,
                        const istream_iterator&lt;T,charT,traits,Distance&gt;&amp; y);
</pre>

<p>
but there is no description of what the operator does (i.e., no Effects
or Returns clause) in 24.5.1.2.
</p>
<p><b>Proposed resolution:</b></p>
<p>
Add paragraph 7 to the end of section 24.5.1.2 with the following text:
</p>

<pre>
   template &lt;class T, class charT, class traits, class Distance&gt;
        bool operator!=(const istream_iterator&lt;T,charT,traits,Distance&gt;&amp; x,
                        const istream_iterator&lt;T,charT,traits,Distance&gt;&amp; y);
</pre>

<p>-7- Returns: !(x == y).</p>
<hr>
<a name="262"><h3>262.&nbsp;Bitmask operator ~ specified incorrectly</h3></a><p><b>Section:</b>&nbsp;17.3.2.1.2 <a href="lib-intro.html#lib.bitmask.types"> [lib.bitmask.types]</a>&nbsp; <b>Status:</b>&nbsp;<a href="lwg-active.html#WP">WP</a>&nbsp; <b>Submitter:</b>&nbsp;Beman Dawes&nbsp; <b>Date:</b>&nbsp;03 Sep 2000</p>
<p>
The ~ operation should be applied after the cast to int_type.
</p>
<p><b>Proposed resolution:</b></p>
<p>
Change 17.3.2.1.2 [lib.bitmask.types] operator~ from:
</p>

<pre>
   bitmask operator~ ( bitmask X )
     { return static_cast&lt; bitmask&gt;(static_cast&lt;int_type&gt;(~ X)); }
</pre>

<p>
to:
</p>

<pre>
   bitmask operator~ ( bitmask X )
     { return static_cast&lt; bitmask&gt;(~static_cast&lt;int_type&gt;(X)); }
</pre>
<hr>
<a name="263"><h3>263.&nbsp;Severe restriction on <tt>basic_string</tt> reference counting</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#WP">WP</a>&nbsp; <b>Submitter:</b>&nbsp;Kevlin Henney&nbsp; <b>Date:</b>&nbsp;04 Sep 2000</p>
<p>
The note in paragraph 6 suggests that the invalidation rules for
references, pointers, and iterators in paragraph 5 permit a reference-
counted implementation (actually, according to paragraph 6, they permit
a "reference counted implementation", but this is a minor editorial fix).
</p>

<p>
However, the last sub-bullet is so worded as to make a reference-counted
implementation unviable. In the following example none of the
conditions for iterator invalidation are satisfied:
</p>

<pre>
    // first example: "*******************" should be printed twice
    string original = "some arbitrary text", copy = original;
    const string &amp; alias = original;

    string::const_iterator i = alias.begin(), e = alias.end();
    for(string::iterator j = original.begin(); j != original.end(); ++j)
        *j = '*';
    while(i != e)
        cout &lt;&lt; *i++;
    cout &lt;&lt; endl;
    cout &lt;&lt; original &lt;&lt; endl;
</pre>

<p>
Similarly, in the following example:
</p>

<pre>
    // second example: "some arbitrary text" should be printed out
    string original = "some arbitrary text", copy = original;
    const string &amp; alias = original;

    string::const_iterator i = alias.begin();
    original.begin();
    while(i != alias.end())
        cout &lt;&lt; *i++;
</pre>

<p>
I have tested this on three string implementations, two of which were
reference counted. The reference-counted implementations gave
"surprising behavior" because they invalidated iterators on
the first call to non-const begin since construction. The current
wording does not permit such invalidation because it does not take
into account the first call since construction, only the first call
since various member and non-member function calls.
</p>
<p><b>Proposed resolution:</b></p>
<p>
Change the following sentence in 21.3 paragraph 5 from
</p>

<blockquote>
    Subsequent to any of the above uses except the forms of insert() and
    erase() which return iterators, the first call to non-const member
    functions operator[](), at(), begin(), rbegin(), end(), or rend().
</blockquote>

<p>to</p>

<blockquote>
    Following construction or any of the above uses, except the forms of
    insert() and erase() that return iterators, the first call to non-
    const member functions operator[](), at(), begin(), rbegin(), end(),
    or rend().
</blockquote>
<hr>
<a name="264"><h3>264.&nbsp;Associative container <tt>insert(i, j)</tt> complexity requirements are not feasible.</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#WP">WP</a>&nbsp; <b>Submitter:</b>&nbsp;John Potter&nbsp; <b>Date:</b>&nbsp;07 Sep 2000</p>
<p>
Table 69 requires linear time if [i, j) is sorted.  Sorted is necessary but not sufficient.
Consider inserting a sorted range of even integers into a set&lt;int&gt; containing the odd
integers in the same range.
</p>

<p><i>Related issue: <a href="lwg-closed.html#102">102</a></i></p>
<p><b>Proposed resolution:</b></p>
<p>
In Table 69, in section 23.1.2, change the complexity clause for
insertion of a range from "N log(size() + N) (N is the distance
from i to j) in general; linear if [i, j) is sorted according to
value_comp()" to "N log(size() + N), where N is the distance
from i to j".
</p>

<p><i>[Copenhagen: Minor fix in proposed resolution: fixed unbalanced
parens in the revised wording.]</i></p>

<p><b>Rationale:</b></p>
<p>
Testing for valid insertions could be less efficient than simply
inserting the elements when the range is not both sorted and between
two adjacent existing elements; this could be a QOI issue.
</p>

<p> 
The LWG considered two other options: (a) specifying that the
complexity was linear if [i, j) is sorted according to value_comp()
and between two adjacent existing elements; or (b) changing to
Klog(size() + N) + (N - K) (N is the distance from i to j and K is the
number of elements which do not insert immediately after the previous
element from [i, j) including the first).  The LWG felt that, since
we can't guarantee linear time complexity whenever the range to be
inserted is sorted, it's more trouble than it's worth to say that it's
linear in some special cases.
</p>
<hr>
<a name="265"><h3>265.&nbsp;std::pair::pair() effects overly restrictive</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#WP">WP</a>&nbsp; <b>Submitter:</b>&nbsp;Martin Sebor&nbsp; <b>Date:</b>&nbsp;11 Sep 2000</p>
<p>
I don't see any requirements on the types of the elements of the
std::pair container in 20.2.2. From the descriptions of the member
functions it appears that they must at least satisfy the requirements of
20.1.3 [lib.copyconstructible] and 20.1.4 [lib.default.con.req], and in
the case of the [in]equality operators also the requirements of 20.1.1
[lib.equalitycomparable] and 20.1.2 [lib.lessthancomparable].
</p>

<p>
I believe that the the CopyConstructible requirement is unnecessary in
the case of 20.2.2, p2.
</p>
<p><b>Proposed resolution:</b></p>
<p>Change the Effects clause in 20.2.2, p2 from</p>

<blockquote>
-2- <b>Effects</b>: Initializes its members as if implemented: <tt> pair() :
first(T1()), second(T2()) {} </tt>
</blockquote>

<p>to</p>

<blockquote>
-2- <b>Effects</b>: Initializes its members as if implemented: <tt> pair() :
first(), second() {} </tt>
</blockquote>
<p><b>Rationale:</b></p>
<p>The existing specification of pair's constructor appears to be a
historical artifact: there was concern that pair's members be properly
zero-initialized when they are built-in types.  At one time there was
uncertainty about whether they would be zero-initialized if the
default constructor was written the obvious way.  This has been
clarified by core issue 178, and there is no longer any doubt that
the straightforward implementation is correct.</p>
<hr>
<a name="266"><h3>266.&nbsp;bad_exception::~bad_exception() missing Effects clause</h3></a><p><b>Section:</b>&nbsp;18.6.2.1 <a href="lib-support.html#lib.bad.exception"> [lib.bad.exception]</a>&nbsp; <b>Status:</b>&nbsp;<a href="lwg-active.html#WP">WP</a>&nbsp; <b>Submitter:</b>&nbsp;Martin Sebor&nbsp; <b>Date:</b>&nbsp;24 Sep 2000</p>
<p>
The synopsis for std::bad_exception lists the function ~bad_exception()
but there is no description of what the function does (the Effects
clause is missing).
</p>
<p><b>Proposed resolution:</b></p>
<p>
Remove the destructor from the class synopses of 
<tt>bad_alloc</tt> (18.4.2.1 <a href="lib-support.html#lib.bad.alloc"> [lib.bad.alloc]</a>),
<tt>bad_cast</tt> (18.5.2 <a href="lib-support.html#lib.bad.cast"> [lib.bad.cast]</a>),
<tt>bad_typeid</tt> (18.5.3 <a href="lib-support.html#lib.bad.typeid"> [lib.bad.typeid]</a>),
and <tt>bad_exception</tt> (18.6.2.1 <a href="lib-support.html#lib.bad.exception"> [lib.bad.exception]</a>).
</p>
<p><b>Rationale:</b></p>
<p>
This is a general problem with the exception classes in clause 18. 
The proposed resolution is to remove the destructors from the class
synopses, rather than to document the destructors' behavior, because
removing them is more consistent with how exception classes are
described in clause 19.
</p>
<hr>
<a name="268"><h3>268.&nbsp;Typo in locale synopsis</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#WP">WP</a>&nbsp; <b>Submitter:</b>&nbsp;Martin Sebor&nbsp; <b>Date:</b>&nbsp;5 Oct 2000</p>
<p>The synopsis of the class std::locale in 22.1.1 contains two typos:
the semicolons after the declarations of the default ctor
locale::locale() and the copy ctor locale::locale(const locale&amp;)
are missing.</p>
<p><b>Proposed resolution:</b></p>
<p>Add the missing semicolons, i.e., change</p>

<pre>
    //  construct/copy/destroy:
        locale() throw()
        locale(const locale&amp; other) throw()
</pre>

<p>in the synopsis in 22.1.1 to</p>

<pre>
    //  construct/copy/destroy:
        locale() throw();
        locale(const locale&amp; other) throw();
</pre>
<hr>
<a name="270"><h3>270.&nbsp;Binary search requirements overly strict</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#WP">WP</a>&nbsp; <b>Submitter:</b>&nbsp;Matt Austern&nbsp; <b>Date:</b>&nbsp;18 Oct 2000</p>
<p>
Each of the four binary search algorithms (lower_bound, upper_bound,
equal_range, binary_search) has a form that allows the user to pass a
comparison function object.  According to 25.3, paragraph 2, that
comparison function object has to be a strict weak ordering.
</p>

<p>
This requirement is slightly too strict.  Suppose we are searching
through a sequence containing objects of type X, where X is some
large record with an integer key.  We might reasonably want to look
up a record by key, in which case we would want to write something
like this:
</p>
<pre>
    struct key_comp {
      bool operator()(const X&amp; x, int n) const {
        return x.key() &lt; n;
      }
    }

    std::lower_bound(first, last, 47, key_comp());
</pre>

<p>
key_comp is not a strict weak ordering, but there is no reason to
prohibit its use in lower_bound.
</p>

<p>
There's no difficulty in implementing lower_bound so that it allows
the use of something like key_comp.  (It will probably work unless an
implementor takes special pains to forbid it.)  What's difficult is
formulating language in the standard to specify what kind of
comparison function is acceptable.  We need a notion that's slightly
more general than that of a strict weak ordering, one that can encompass
a comparison function that involves different types.  Expressing that
notion may be complicated.
</p>

<p><i>Additional questions raised at the Toronto meeting:</i></p>
<ul>
<li> Do we really want to specify what ordering the implementor must
     use when calling the function object?  The standard gives 
     specific expressions when describing these algorithms, but it also
     says that other expressions (with different argument order) are
     equivalent.</li>
<li> If we are specifying ordering, note that the standard uses both
     orderings when describing <tt>equal_range</tt>.</li>
<li> Are we talking about requiring these algorithms to work properly
     when passed a binary function object whose two argument types
     are not the same, or are we talking about requirements when
     they are passed a binary function object with several overloaded
     versions of <tt>operator()</tt>?</li>
<li> The definition of a strict weak ordering does not appear to give
     any guidance on issues of overloading; it only discusses expressions,
     and all of the values in these expressions are of the same type.
     Some clarification would seem to be in order.</li>
</ul>

<p><i>Additional discussion from Copenhagen:</i></p>
<ul>
<li>It was generally agreed that there is a real defect here: if
the predicate is merely required to be a Strict Weak Ordering, then
it's possible to pass in a function object with an overloaded
operator(), where the version that's actually called does something
completely inappropriate.  (Such as returning a random value.)</li>

<li>An alternative formulation was presented in a paper distributed by
David Abrahams at the meeting, "Binary Search with Heterogeneous
Comparison", J16-01/0027 = WG21 N1313: Instead of viewing the
predicate as a Strict Weak Ordering acting on a sorted sequence, view
the predicate/value pair as something that partitions a sequence.
This is almost equivalent to saying that we should view binary search
as if we are given a unary predicate and a sequence, such that f(*p)
is true for all p below a specific point and false for all p above it.
The proposed resolution is based on that alternative formulation.</li>
</ul>
<p><b>Proposed resolution:</b></p>

<p>Change 25.3 [lib.alg.sorting] paragraph 3 from:</p>

<blockquote>
  3 For all algorithms that take Compare, there is a version that uses
  operator&lt; instead. That is, comp(*i, *j) != false defaults to *i &lt;
  *j != false. For the algorithms to work correctly, comp has to
  induce a strict weak ordering on the values.
</blockquote>

<p>to:</p>

<blockquote>
  3 For all algorithms that take Compare, there is a version that uses
  operator&lt; instead. That is, comp(*i, *j) != false defaults to *i
  &lt; *j != false. For algorithms other than those described in
  lib.alg.binary.search (25.3.3) to work correctly, comp has to induce
  a strict weak ordering on the values.
</blockquote>

<p>Add the following paragraph after 25.3 [lib.alg.sorting] paragraph 5:</p>

<blockquote>
  -6- A sequence [start, finish) is partitioned with respect to an
  expression f(e) if there exists an integer n such that
  for all 0 &lt;= i &lt; distance(start, finish), f(*(begin+i)) is true if
  and only if i &lt; n.
</blockquote>

<p>Change 25.3.3 [lib.alg.binary.search] paragraph 1 from:</p>

<blockquote>
  -1- All of the algorithms in this section are versions of binary
   search and assume that the sequence being searched is in order
   according to the implied or explicit comparison function. They work
   on non-random access iterators minimizing the number of
   comparisons, which will be logarithmic for all types of
   iterators. They are especially appropriate for random access
   iterators, because these algorithms do a logarithmic number of
   steps through the data structure. For non-random access iterators
   they execute a linear number of steps.
</blockquote>

<p>to:</p>

<blockquote>
   -1- All of the algorithms in this section are versions of binary
    search and assume that the sequence being searched is partitioned
    with respect to an expression formed by binding the search key to
    an argument of the implied or explicit comparison function. They
    work on non-random access iterators minimizing the number of
    comparisons, which will be logarithmic for all types of
    iterators. They are especially appropriate for random access
    iterators, because these algorithms do a logarithmic number of
    steps through the data structure. For non-random access iterators
    they execute a linear number of steps.
</blockquote>

<p>Change 25.3.3.1 [lib.lower.bound] paragraph 1 from:</p>

<blockquote>
   -1- Requires: Type T is LessThanComparable
    (lib.lessthancomparable). 
</blockquote>

<p>to:</p>

<blockquote>
   -1- Requires: The elements e of [first, last) are partitioned with
   respect to the expression e &lt; value or comp(e, value)
</blockquote>


<p>Remove 25.3.3.1 [lib.lower.bound] paragraph 2:</p>

<blockquote>
   -2- Effects: Finds the first position into which value can be
    inserted without violating the ordering. 
</blockquote>

<p>Change 25.3.3.2 [lib.upper.bound] paragraph 1 from:</p>

<blockquote>
  -1- Requires: Type T is LessThanComparable (lib.lessthancomparable).
</blockquote>

<p>to:</p>

<blockquote>
   -1- Requires: The elements e of [first, last) are partitioned with
   respect to the expression !(value &lt; e) or !comp(value, e)
</blockquote>

<p>Remove 25.3.3.2 [lib.upper.bound] paragraph 2:</p>

<blockquote>
   -2- Effects: Finds the furthermost position into which value can be
    inserted without violating the ordering.
</blockquote>

<p>Change 25.3.3.3 [lib.equal.range] paragraph 1 from:</p>

<blockquote>
   -1- Requires: Type T is LessThanComparable
    (lib.lessthancomparable).
</blockquote>

<p>to:</p>

<blockquote>
   -1- Requires: The elements e of [first, last) are partitioned with
   respect to the expressions e &lt; value and !(value &lt; e) or
   comp(e, value) and !comp(value, e).  Also, for all elements e of
   [first, last), e &lt; value implies !(value &lt; e) or comp(e,
   value) implies !comp(value, e)
</blockquote>

<p>Change 25.3.3.3 [lib.equal.range] paragraph 2 from:</p>

<blockquote>
   -2- Effects: Finds the largest subrange [i, j) such that the value
    can be inserted at any iterator k in it without violating the
    ordering. k satisfies the corresponding conditions: !(*k &lt; value)
    &amp;&amp; !(value &lt; *k) or comp(*k, value) == false &amp;&amp; comp(value, *k) ==
    false.
</blockquote>

<p>to:</p>

<pre>
   -2- Returns: 
         make_pair(lower_bound(first, last, value),
                   upper_bound(first, last, value))
       or
         make_pair(lower_bound(first, last, value, comp),
                   upper_bound(first, last, value, comp))
</pre>

<p>Change 25.3.3.3 [lib.binary.search] paragraph 1 from:</p>

<blockquote>
   -1- Requires: Type T is LessThanComparable
    (lib.lessthancomparable).
</blockquote>

<p>to:</p>

<blockquote>
   -1- Requires: The elements e of [first, last) are partitioned with
   respect to the expressions e &lt; value and !(value &lt; e) or comp(e,
   value) and !comp(value, e). Also, for all elements e of [first,
   last), e &lt; value implies !(value &lt; e) or comp(e, value) implies
   !comp(value, e)
</blockquote>

<p><i>[Copenhagen: Dave Abrahams provided this wording]</i></p>

<p><i>[Redmond: Minor changes in wording.  (Removed "non-negative", and
changed the "other than those described in" wording.) Also, the LWG
decided to accept the "optional" part.]</i></p>

<p><b>Rationale:</b></p>
<p>The proposed resolution reinterprets binary search. Instead of
thinking about searching for a value in a sorted range, we view that
as an important special case of a more general algorithm: searching
for the partition point in a partitioned range.</p>

<p>We also add a guarantee that the old wording did not: we ensure
that the upper bound is no earlier than the lower bound, that
the pair returned by equal_range is a valid range, and that the first
part of that pair is the lower bound.</p>
<hr>
<a name="271"><h3>271.&nbsp;basic_iostream missing typedefs</h3></a><p><b>Section:</b>&nbsp;27.6.1.5 <a href="lib-iostreams.html#lib.iostreamclass"> [lib.iostreamclass]</a>&nbsp; <b>Status:</b>&nbsp;<a href="lwg-active.html#WP">WP</a>&nbsp; <b>Submitter:</b>&nbsp;Martin Sebor&nbsp; <b>Date:</b>&nbsp;02 Nov 2000</p>
<p>
Class template basic_iostream has no typedefs.  The typedefs it
inherits from its base classes can't be used, since (for example)
basic_iostream&lt;T&gt;::traits_type is ambiguous.
</p>
<p><b>Proposed resolution:</b></p>

<p>Add the following to basic_iostream's class synopsis in 
27.6.1.5 <a href="lib-iostreams.html#lib.iostreamclass"> [lib.iostreamclass]</a>, immediately after <tt>public</tt>:</p>

<pre>
  // types:
  typedef charT                     char_type;
  typedef typename traits::int_type int_type;
  typedef typename traits::pos_type pos_type;
  typedef typename traits::off_type off_type;
  typedef traits                    traits_type;
</pre>
<hr>
<a name="272"><h3>272.&nbsp;Missing parentheses around subexpression</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#WP">WP</a>&nbsp; <b>Submitter:</b>&nbsp;Martin Sebor&nbsp; <b>Date:</b>&nbsp;02 Nov 2000</p>
<p>
27.4.4.3, p4 says about the postcondition of the function: If
rdbuf()!=0 then state == rdstate(); otherwise
rdstate()==state|ios_base::badbit.
</p>

<p>
The expression on the right-hand-side of the operator==() needs to be
parenthesized in order for the whole expression to ever evaluate to
anything but non-zero.
</p>
<p><b>Proposed resolution:</b></p>
<p>
Add parentheses like so: rdstate()==(state|ios_base::badbit).
</p>
<hr>
<a name="273"><h3>273.&nbsp;Missing ios_base qualification on members of a dependent class</h3></a><p><b>Section:</b>&nbsp;27 <a href="lib-iostreams.html#lib.input.output"> [lib.input.output]</a>&nbsp; <b>Status:</b>&nbsp;<a href="lwg-active.html#WP">WP</a>&nbsp; <b>Submitter:</b>&nbsp;Martin Sebor&nbsp; <b>Date:</b>&nbsp;02 Nov 2000</p>
<p>27.5.2.4.2, p4, and 27.8.1.6, p2, 27.8.1.7, p3, 27.8.1.9, p2,
27.8.1.10, p3 refer to in and/or out w/o ios_base:: qualification.
That's incorrect since the names are members of a dependent base
class (14.6.2 [temp.dep]) and thus not visible.</p>
<p><b>Proposed resolution:</b></p>
<p>Qualify the names with the name of the class of which they are
members, i.e., ios_base.</p>
<hr>
<a name="274"><h3>274.&nbsp;a missing/impossible allocator requirement</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#WP">WP</a>&nbsp; <b>Submitter:</b>&nbsp;Martin Sebor&nbsp; <b>Date:</b>&nbsp;02 Nov 2000</p>
<p>
I see that table 31 in 20.1.5, p3 allows T in std::allocator&lt;T&gt; to be of
any type. But the synopsis in 20.4.1 calls for allocator&lt;&gt;::address() to
be overloaded on reference and const_reference, which is ill-formed for
all T = const U. In other words, this won't work:
</p>

<p>
template class std::allocator&lt;const int&gt;;
</p>

<p>
The obvious solution is to disallow specializations of allocators on
const types. However, while containers' elements are required to be
assignable (which rules out specializations on const T's), I think that
allocators might perhaps be potentially useful for const values in other
contexts. So if allocators are to allow const types a partial
specialization of std::allocator&lt;const T&gt; would probably have to be
provided.
</p>
<p><b>Proposed resolution:</b></p>
<p>Change the text in row 1, column 2 of table 32 in 20.1.5, p3 from</p>

    <blockquote>
    any type
    </blockquote>

<p>to</p>
    <blockquote>
    any non-const, non-reference type
    </blockquote>

<p><i>[Redmond: previous proposed resolution was "any non-const,
non-volatile, non-reference type".  Got rid of the "non-volatile".]</i></p>

<p><b>Rationale:</b></p>
<p>
Two resolutions were originally proposed: one that partially
specialized std::allocator for const types, and one that said an
allocator's value type may not be const.  The LWG chose the second.
The first wouldn't be appropriate, because allocators are intended for
use by containers, and const value types don't work in containers.
Encouraging the use of allocators with const value types would only
lead to unsafe code.
</p>
<p>
The original text for proposed resolution 2 was modified so that it
also forbids volatile types and reference types.
</p>

<p><i>[Cura&ccedil;ao: LWG double checked and believes volatile is correctly
excluded from the PR.]</i></p>

<hr>
<a name="275"><h3>275.&nbsp;Wrong type in num_get::get() overloads</h3></a><p><b>Section:</b>&nbsp;22.2.2.1.1 <a href="lib-locales.html#lib.facet.num.get.members"> [lib.facet.num.get.members]</a>&nbsp; <b>Status:</b>&nbsp;<a href="lwg-active.html#WP">WP</a>&nbsp; <b>Submitter:</b>&nbsp;Matt Austern&nbsp; <b>Date:</b>&nbsp;02 Nov 2000</p>
<p>
In 22.2.2.1.1, we have a list of overloads for num_get&lt;&gt;::get().
There are eight overloads, all of which are identical except for the
last parameter.  The overloads are: 
</p>
<ul>
<li> long&amp; </li>
<li> unsigned short&amp; </li>
<li> unsigned int&amp; </li>
<li> unsigned long&amp; </li>
<li> short&amp; </li>
<li> double&amp; </li>
<li> long double&amp; </li>
<li> void*&amp; </li>
</ul>

<p>
There is a similar list, in 22.2.2.1.2, of overloads for
num_get&lt;&gt;::do_get().  In this list, the last parameter has
the types: 
</p>
<ul>
<li> long&amp; </li>
<li> unsigned short&amp; </li>
<li> unsigned int&amp; </li>
<li> unsigned long&amp; </li>
<li> float&amp; </li>
<li> double&amp; </li>
<li> long double&amp; </li>
<li> void*&amp; </li>
</ul>

<p>
These two lists are not identical.  They should be, since
<tt>get</tt> is supposed to call <tt>do_get</tt> with exactly
the arguments it was given.
</p>
<p><b>Proposed resolution:</b></p>
<p>In 22.2.2.1.1 <a href="lib-locales.html#lib.facet.num.get.members"> [lib.facet.num.get.members]</a>, change</p>
<pre>
  iter_type get(iter_type in, iter_type end, ios_base&amp; str,
                ios_base::iostate&amp; err, short&amp; val) const;
</pre>
<p>to</p>
<pre>
  iter_type get(iter_type in, iter_type end, ios_base&amp; str,
                ios_base::iostate&amp; err, float&amp; val) const;
</pre>
<hr>
<a name="276"><h3>276.&nbsp;Assignable requirement for container value type overly strict</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#WP">WP</a>&nbsp; <b>Submitter:</b>&nbsp;Peter Dimov&nbsp; <b>Date:</b>&nbsp;07 Nov 2000</p>
<p>
23.1/3 states that the objects stored in a container must be
Assignable.  23.3.1 <a href="lib-containers.html#lib.map"> [lib.map]</a>, paragraph 2,
states that map satisfies all requirements for a container, while in
the same time defining value_type as pair&lt;const Key, T&gt; - a type
that is not Assignable.
</p>

<p>
It should be noted that there exists a valid and non-contradictory
interpretation of the current text. The wording in 23.1/3 avoids 
mentioning value_type, referring instead to "objects stored in a
container." One might argue that map does not store objects of
type map::value_type, but of map::mapped_type instead, and that the
Assignable requirement applies to map::mapped_type, not
map::value_type.
</p>

<p>
However, this makes map a special case (other containers store objects of
type value_type) and the Assignable requirement is needlessly restrictive in
general.
</p>

<p>
For example, the proposed resolution of active library issue 
<a href="lwg-defects.html#103">103</a> is to make set::iterator a constant iterator; this
means that no set operations can exploit the fact that the stored
objects are Assignable.
</p>

<p>
This is related to, but slightly broader than, closed issue
<a href="lwg-closed.html#140">140</a>.
</p>
<p><b>Proposed resolution:</b></p>
<p>23.1/3: Strike the trailing part of the sentence:</p>
    <blockquote>
    , and the additional requirements of Assignable types from 23.1/3
    </blockquote>
<p>so that it reads:</p>
    <blockquote>
    -3- The type of objects stored in these components must meet the 
    requirements of CopyConstructible types (lib.copyconstructible).
    </blockquote>

<p>23.1/4: Modify to make clear that this requirement is not for all 
containers.  Change to:</p>

<blockquote>
-4- Table 64 defines the Assignable requirement.  Some containers 
require this property of the types to be stored in the container.  T is 
the type used to instantiate the container. t is a value of T, and u is 
a value of (possibly const) T.
</blockquote>

<p>23.1, Table 65: in the first row, change "T is Assignable" to "T is
CopyConstructible".</p>

<p>23.2.1/2: Add sentence for Assignable requirement.  Change to:</p>

<blockquote>
-2- A deque satisfies all of the requirements of a container and of a 
reversible container (given in tables in lib.container.requirements) and 
of a sequence, including the optional sequence requirements 
(lib.sequence.reqmts).  In addition to the requirements on the stored 
object described in 23.1[lib.container.requirements], the stored object 
must also meet the requirements of Assignable.  Descriptions are 
provided here only for operations on deque that are not described in one 
of these tables or for operations where there is additional semantic 
information.
</blockquote>

<p>23.2.2/2:  Add Assignable requirement to specific methods of list.  
Change to:</p>

<blockquote>
<p>-2- A list satisfies all of the requirements of a container and of a 
reversible container (given in two tables in lib.container.requirements) 
and of a sequence, including most of the the optional sequence 
requirements (lib.sequence.reqmts). The exceptions are the operator[] 
and at member functions, which are not provided. 

[Footnote: These member functions are only provided by containers whose 
iterators are random access iterators. --- end foonote]
</p>

<p>list does not require the stored type T to be Assignable unless the 
following methods are instantiated:

[Footnote: Implementors are permitted but not required to take advantage 
of T's Assignable properties for these methods. -- end foonote]
</p>
<pre>
     list&lt;T,Allocator&gt;&amp; operator=(const list&lt;T,Allocator&gt;&amp;  x );
     template &lt;class InputIterator&gt;
       void assign(InputIterator first, InputIterator last);
     void assign(size_type n, const T&amp; t);
</pre>


<p>Descriptions are provided here only for operations on list that are not 
described in one of these tables or for operations where there is 
additional semantic information.</p>
</blockquote>

<p>23.2.4/2:   Add sentence for Assignable requirement.  Change to:</p>

<blockquote>
-2- A vector satisfies all of the requirements of a container and of a 
reversible container (given in two tables in lib.container.requirements) 
and of a sequence, including most of the optional sequence requirements 
(lib.sequence.reqmts). The exceptions are the push_front and pop_front 
member functions, which are not provided.  In addition to the 
requirements on the stored object described in 
23.1[lib.container.requirements], the stored object must also meet the 
requirements of Assignable.  Descriptions are provided here only for 
operations on vector that are not described in one of these tables or 
for operations where there is additional semantic information.
</blockquote>
<p><b>Rationale:</b></p>
<p>list, set, multiset, map, multimap are able to store non-Assignables.
However, there is some concern about <tt>list&lt;T&gt;</tt>:
although in general there's no reason for T to be Assignable, some
implementations of the member functions <tt>operator=</tt> and
<tt>assign</tt> do rely on that requirement.  The LWG does not want
to forbid such implementations.</p>

<p>Note that the type stored in a standard container must still satisfy
the requirements of the container's allocator; this rules out, for
example, such types as "const int".  See issue <a href="lwg-defects.html#274">274</a>
for more details.
</p>

<p>In principle we could also relax the "Assignable" requirement for
individual <tt>vector</tt> member functions, such as
<tt>push_back</tt>.  However, the LWG did not see great value in such
selective relaxation.  Doing so would remove implementors' freedom to
implement <tt>vector::push_back</tt> in terms of
<tt>vector::insert</tt>.</p>

<hr>
<a name="278"><h3>278.&nbsp;What does iterator validity mean?</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#WP">WP</a>&nbsp; <b>Submitter:</b>&nbsp;P.J. Plauger&nbsp; <b>Date:</b>&nbsp;27 Nov 2000</p>
<p>
Section 23.2.2.4 [lib.list.ops] states that
</p>
<pre>
  void splice(iterator position, list&lt;T, Allocator&gt;&amp; x);
</pre>
<p>
<i>invalidates</i> all iterators and references to list <tt>x</tt>.
</p>

<p>
But what does the C++ Standard mean by "invalidate"?  You
can still dereference the iterator to a spliced list element, but
you'd better not use it to delimit a range within the original
list. For the latter operation, it has definitely lost some of its
validity.
</p>

<p>
If we accept the proposed resolution to issue <a href="lwg-defects.html#250">250</a>,
then we'd better clarify that a "valid" iterator need no
longer designate an element within the same container as it once did.
We then have to clarify what we mean by invalidating a past-the-end
iterator, as when a vector or string grows by reallocation. Clearly,
such an iterator has a different kind of validity. Perhaps we should
introduce separate terms for the two kinds of "validity."
</p>
<p><b>Proposed resolution:</b></p>
<p>Add the following text to the end of section 24.1 <a href="lib-iterators.html#lib.iterator.requirements"> [lib.iterator.requirements]</a>,
after paragraph 5:</p>
<blockquote>
An <i>invalid</i> iterator is an iterator that may be
singular. [Footnote: This definition applies to pointers, since
pointers are iterators. The effect of dereferencing an iterator that
has been invalidated is undefined.]
</blockquote>

<p><i>[post-Copenhagen: Matt provided wording.]</i></p>

<p><i>[Redmond: General agreement with the intent, some objections to
the wording.  Dave provided new wording.]</i></p>
<p><b>Rationale:</b></p>
<p>This resolution simply defines a term that the Standard uses but
  never defines, "invalid", in terms of a term that is defined,
  "singular".</p>

<p>Why do we say "may be singular", instead of "is singular"?  That's
  becuase a valid iterator is one that is known to be nonsingular.
  Invalidating an iterator means changing it in such a way that it's
  no longer known to be nonsingular.  An example: inserting an
  element into the middle of a vector is correctly said to invalidate
  all iterators pointing into the vector.  That doesn't necessarily
  mean they all become singular.</p>
<hr>
<a name="281"><h3>281.&nbsp;std::min() and max() requirements overly restrictive</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#WP">WP</a>&nbsp; <b>Submitter:</b>&nbsp;Martin Sebor&nbsp; <b>Date:</b>&nbsp;02 Dec 2000</p>
<p>The requirements in 25.3.7, p1 and 4 call for T to satisfy the
requirements of <tt>LessThanComparable</tt> (20.1.2 <a href="lib-utilities.html#lib.lessthancomparable"> [lib.lessthancomparable]</a>)
and <tt>CopyConstructible</tt> (20.1.3 <a href="lib-utilities.html#lib.copyconstructible"> [lib.copyconstructible]</a>).
Since the functions take and return their arguments and result by
const reference, I believe the <tt>CopyConstructible</tt> requirement
is unnecessary.
</p>
<p><b>Proposed resolution:</b></p>
<p>Remove the <tt>CopyConstructible</tt> requirement. Specifically, replace
25.3.7, p1 with</p>
<p><b>-1- Requires:</b> Type T is <tt>LessThanComparable</tt> 
(20.1.2 <a href="lib-utilities.html#lib.lessthancomparable"> [lib.lessthancomparable]</a>).
</p>
<p>and replace 25.3.7, p4 with</p>
<p><b>-4- Requires:</b> Type T is <tt>LessThanComparable</tt> 
(20.1.2 <a href="lib-utilities.html#lib.lessthancomparable"> [lib.lessthancomparable]</a>).
</p>
<hr>
<a name="282"><h3>282.&nbsp;What types does numpunct grouping refer to?</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#WP">WP</a>&nbsp; <b>Submitter:</b>&nbsp;Howard Hinnant&nbsp; <b>Date:</b>&nbsp;5 Dec 2000</p>
<p>
Paragraph 16 mistakenly singles out integral types for inserting 
thousands_sep() characters.  This conflicts with the syntax for floating 
point numbers described under 22.2.3.1/2.
</p>
<p><b>Proposed resolution:</b></p>
<p>Change paragraph 16 from:</p>

<blockquote>
For integral types, punct.thousands_sep() characters are inserted into 
the sequence as determined by the value returned by punct.do_grouping() 
using the method described in 22.2.3.1.2 <a href="lib-locales.html#lib.facet.numpunct.virtuals"> [lib.facet.numpunct.virtuals]</a>.
</blockquote>

<p>To:</p>

<blockquote>
For arithmetic types, punct.thousands_sep() characters are inserted into 
the sequence as determined by the value returned by punct.do_grouping() 
using the method described in 22.2.3.1.2 <a href="lib-locales.html#lib.facet.numpunct.virtuals"> [lib.facet.numpunct.virtuals]</a>.
</blockquote>

<p><i>[
Copenhagen: Opinions were divided about whether this is actually an
inconsistency, but at best it seems to have been unintentional.  This
is only an issue for floating-point output: The standard is
unambiguous that implementations must parse thousands_sep characters
when performing floating-point.  The standard is also unambiguous that
this requirement does not apply to the "C" locale.
]</i></p>

<p><i>[
A survey of existing practice is needed; it is believed that some
implementations do insert thousands_sep characters for floating-point
output and others fail to insert thousands_sep characters for 
floating-point input even though this is unambiguously required by the
standard.
]</i></p>

<p><i>[Post-Cura&ccedil;ao: the above proposed resolution is the consensus of
Howard, Bill, Pete, Benjamin, Nathan, Dietmar, Boris, and Martin.]</i></p>

<hr>
<a name="283"><h3>283.&nbsp;std::replace() requirement incorrect/insufficient</h3></a><p><b>Section:</b>&nbsp;25.2.4 <a href="lib-algorithms.html#lib.alg.replace"> [lib.alg.replace]</a>&nbsp; <b>Status:</b>&nbsp;<a href="lwg-active.html#WP">WP</a>&nbsp; <b>Submitter:</b>&nbsp;Martin Sebor&nbsp; <b>Date:</b>&nbsp;15 Dec 2000</p>
<p>
(revision of the further discussion)
There are a number of problems with the requires clauses for the
algorithms in 25.1 and 25.2. The requires clause of each algorithm
should describe the necessary and sufficient requirements on the inputs
to the algorithm such that the algorithm compiles and runs properly.
Many of the requires clauses fail to do this. Here is a summary of the kinds
of mistakes:
</p>

<ol>
<li>
Use of EqualityComparable, which only puts requirements on a single
type, when in fact an equality operator is required between two
different types, typically either T and the iterator's value type
or between the value types of two different iterators.
</li>
<li>
Use of Assignable for T when in fact what was needed is Assignable
for the value_type of the iterator, and convertability from T to the
value_type of the iterator. Or for output iterators, the requirement
should be that T is writable to the iterator (output iterators do
not have value types).
</li>
</ol>

<p>
Here is the list of algorithms that contain mistakes:
</p>

<ul>
<li>25.1.2 std::find</li>
<li>25.1.6 std::count</li>
<li>25.1.8 std::equal</li>
<li>25.1.9 std::search, std::search_n</li>
<li>25.2.4 std::replace, std::replace_copy</li>
<li>25.2.5 std::fill</li>
<li>25.2.7 std::remove, std::remove_copy</li>
</ul>

<p>
Also, in the requirements for EqualityComparable, the requirement that
the operator be defined for const objects is lacking.
</p>

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

<p>20.1.1 Change p1 from</p>

<p>In Table 28, <tt>T</tt> is a type to be supplied by a C++ program
instantiating a template, <tt>a</tt>, <tt>b</tt>, and <tt>c</tt> are
values of type <tt>T</tt>.
</p>

<p>to</p>

<p>
In Table 28, <tt>T</tt> is a type to be supplied by a C++ program
instantiating a template, <tt>a</tt>, <tt>b</tt>, and <tt>c</tt> are
values of type <tt>const T</tt>.
</p>

<p>25 Between p8 and p9</p>

<p>Add the following sentence:</p>

<p>When the description of an algorithm gives an expression such as
<tt>*first == value</tt> for a condition, it is required that the expression
evaluate to either true or false in boolean contexts.</p>

<p>25.1.2 Change p1 by deleting the requires clause.</p>

<p>25.1.6 Change p1 by deleting the requires clause.</p>

<p>25.1.9</p>

<p>Change p4 from</p>

<p>-4- Requires: Type <tt>T</tt> is <tt>EqualityComparable</tt>
(20.1.1), type Size is convertible to integral type (4.7.12.3).
</p>

<p>to</p>

<p>-4- Requires: The type <tt>Size</tt> is convertible to integral
type (4.7.12.3).</p>

<p>25.2.4 Change p1 from</p>

<p>-1- Requires: Type <tt>T</tt> is <tt>Assignable</tt> (23.1 ) (and, for <tt>replace()</tt>, <tt>EqualityComparable</tt> (20.1.1 )).</p>

<p>to</p>

<p>-1- Requires: The expression <tt>*first = new_value</tt> must be valid.</p>

<p>and change p4 from</p>

<p>-4- Requires: Type <tt>T</tt> is <tt>Assignable</tt> (23.1) (and,
for <tt>replace_copy()</tt>, <tt>EqualityComparable</tt>
(20.1.1)). The ranges <tt>[first, last)</tt> and <tt>[result, result +
(last - first))</tt> shall not overlap.</p>

<p>to</p>

<p>-4- Requires: The results of the expressions <tt>*first</tt> and
<tt>new_value</tt> must be writable to the result output iterator. The
ranges <tt>[first, last)</tt> and <tt>[result, result + (last -
first))</tt> shall not overlap.</p>


<p>25.2.5 Change p1 from</p>

<p>-1- Requires: Type <tt>T</tt> is <tt>Assignable</tt> (23.1). The
type <tt>Size</tt> is convertible to an integral type (4.7.12.3).</p>

<p>to</p>

<p>-1- Requires: The expression <tt>value</tt> must be is writable to
the output iterator. The type <tt>Size</tt> is convertible to an
integral type (4.7.12.3).</p>

<p>25.2.7 Change p1 from</p>

<p>-1- Requires: Type <tt>T</tt> is <tt>EqualityComparable</tt> (20.1.1).</p>

<p>to</p>

<p>
-1- Requires: The value type of the iterator must be
<tt>Assignable</tt> (23.1).
</p>

<p><b>Rationale:</b></p>
<p>
The general idea of the proposed solution is to remove the faulty
requires clauses and let the returns and effects clauses speak for
themselves. That is, the returns clauses contain expressions that must
be valid, and therefore already imply the correct requirements. In
addition, a sentence is added at the beginning of chapter 25 saying
that expressions given as conditions must evaluate to true or false in
a boolean context. An alternative would be to say that the type of
these condition expressions must be literally bool, but that would be
imposing a greater restriction that what the standard currently says
(which is convertible to bool).
</p>
<hr>
<a name="284"><h3>284.&nbsp;unportable example in 20.3.7, p6</h3></a><p><b>Section:</b>&nbsp;20.3.7 <a href="lib-utilities.html#lib.function.pointer.adaptors"> [lib.function.pointer.adaptors]</a>&nbsp; <b>Status:</b>&nbsp;<a href="lwg-active.html#WP">WP</a>&nbsp; <b>Submitter:</b>&nbsp;Martin Sebor&nbsp; <b>Date:</b>&nbsp;26 Dec 2000</p>
<p>The example in 20.3.7 <a href="lib-utilities.html#lib.function.pointer.adaptors"> [lib.function.pointer.adaptors]</a>, p6 shows how to use the C
library function <tt>strcmp()</tt> with the function pointer adapter
<tt>ptr_fun()</tt>. But since it's unspecified whether the C library
functions have <tt>extern "C"</tt> or <tt>extern
"C++"</tt> linkage [17.4.2.2 <a href="lib-intro.html#lib.using.linkage"> [lib.using.linkage]</a>], and since
function pointers with different the language linkage specifications
(7.5 <a href="dcl.html#dcl.link"> [dcl.link]</a>) are incompatible, whether this example is
well-formed is unspecified.
</p>
<p><b>Proposed resolution:</b></p>
<p>Change 20.3.7 <a href="lib-utilities.html#lib.function.pointer.adaptors"> [lib.function.pointer.adaptors]</a> paragraph 6 from:</p>
<blockquote>
  <p>[<i>Example:</i></p>
  <pre>
    replace_if(v.begin(), v.end(), not1(bind2nd(ptr_fun(strcmp), "C")), "C++");
  </pre>
  <p>replaces each <tt>C</tt> with <tt>C++</tt> in sequence <tt>v</tt>.</p>
</blockquote>


<p>to:</p>
<blockquote>
  <p>[<i>Example:</i></p>
  <pre>
    int compare(const char*, const char*);
    replace_if(v.begin(), v.end(),
               not1(bind2nd(ptr_fun(compare), "abc")), "def");
  </pre>
  <p>replaces each <tt>abc</tt> with <tt>def</tt> in sequence <tt>v</tt>.</p>
</blockquote>

<p>Also, remove footnote 215 in that same paragraph.</p>

<p><i>[Copenhagen: Minor change in the proposed resolution.  Since this
issue deals in part with C and C++ linkage, it was believed to be too
confusing for the strings in the example to be "C" and "C++".
]</i></p>

<p><i>[Redmond: More minor changes.  Got rid of the footnote (which
seems to make a sweeping normative requirement, even though footnotes
aren't normative), and changed the sentence after the footnote so that
it corresponds to the new code fragment.]</i></p>

<hr>
<a name="285"><h3>285.&nbsp;minor editorial errors in fstream ctors</h3></a><p><b>Section:</b>&nbsp;27.8.1.6 <a href="lib-iostreams.html#lib.ifstream.cons"> [lib.ifstream.cons]</a>&nbsp; <b>Status:</b>&nbsp;<a href="lwg-active.html#WP">WP</a>&nbsp; <b>Submitter:</b>&nbsp;Martin Sebor&nbsp; <b>Date:</b>&nbsp;31 Dec 2000</p>
<p>27.8.1.6 <a href="lib-iostreams.html#lib.ifstream.cons"> [lib.ifstream.cons]</a>, p2, 27.8.1.9 <a href="lib-iostreams.html#lib.ofstream.cons"> [lib.ofstream.cons]</a>, p2, and
27.8.1.12 <a href="lib-iostreams.html#lib.fstream.cons"> [lib.fstream.cons]</a>, p2 say about the effects of each constructor:
</p>

<p>... If that function returns a null pointer, calls
<tt>setstate(failbit)</tt> (which may throw <tt>ios_base::failure</tt>).
</p>

<p>The parenthetical note doesn't apply since the ctors cannot throw an
exception due to the requirement in 27.4.4.1 <a href="lib-iostreams.html#lib.basic.ios.cons"> [lib.basic.ios.cons]</a>, p3 
that <tt>exceptions()</tt> be initialized to <tt>ios_base::goodbit</tt>.
</p>
<p><b>Proposed resolution:</b></p>
<p>
Strike the parenthetical note from the Effects clause in each of the
paragraphs mentioned above.
</p>
<hr>
<a name="286"><h3>286.&nbsp;&lt;cstdlib&gt; requirements missing size_t typedef</h3></a><p><b>Section:</b>&nbsp;25.4 <a href="lib-algorithms.html#lib.alg.c.library"> [lib.alg.c.library]</a>&nbsp; <b>Status:</b>&nbsp;<a href="lwg-active.html#WP">WP</a>&nbsp; <b>Submitter:</b>&nbsp;Judy Ward&nbsp; <b>Date:</b>&nbsp;30 Dec 2000</p>
<p>
The &lt;cstdlib&gt; header file contains prototypes for bsearch and
qsort (C++ Standard section 25.4 paragraphs 3 and 4) and other
prototypes (C++ Standard section 21.4 paragraph 1 table 49) that
require the typedef size_t. Yet size_t is not listed in the
&lt;cstdlib&gt; synopsis table 78 in section 25.4.
</p>
<p><b>Proposed resolution:</b></p>
<p>
Add the type size_t to Table 78 (section 25.4) and add
the type size_t &lt;cstdlib&gt; to Table 97 (section C.2).
</p>
<p><b>Rationale:</b></p>
<p>Since size_t is in &lt;stdlib.h&gt;, it must also be in &lt;cstdlib&gt;.</p>
<hr>
<a name="288"><h3>288.&nbsp;&lt;cerrno&gt; requirements missing macro EILSEQ</h3></a><p><b>Section:</b>&nbsp;19.3 <a href="lib-diagnostics.html#lib.errno"> [lib.errno]</a>&nbsp; <b>Status:</b>&nbsp;<a href="lwg-active.html#WP">WP</a>&nbsp; <b>Submitter:</b>&nbsp;Judy Ward&nbsp; <b>Date:</b>&nbsp;30 Dec 2000</p>
<p>
ISO/IEC 9899:1990/Amendment1:1994 Section 4.3 States: "The list
of macros defined in &lt;errno.h&gt; is adjusted to include a new
macro, EILSEQ"
</p>

<p>
ISO/IEC 14882:1998(E) section 19.3 does not refer
to the above amendment.
</p>

<p><b>Proposed resolution:</b></p>
<p>
Update Table 26 (section 19.3) "Header  &lt;cerrno&gt; synopsis"
and Table 95 (section C.2) "Standard Macros" to include EILSEQ.
</p>
<hr>
<a name="291"><h3>291.&nbsp;Underspecification of set algorithms</h3></a><p><b>Section:</b>&nbsp;25.3.5 <a href="lib-algorithms.html#lib.alg.set.operations"> [lib.alg.set.operations]</a>&nbsp; <b>Status:</b>&nbsp;<a href="lwg-active.html#WP">WP</a>&nbsp; <b>Submitter:</b>&nbsp;Matt Austern&nbsp; <b>Date:</b>&nbsp;03 Jan 2001</p>
<p>
The standard library contains four algorithms that compute set
operations on sorted ranges: <tt>set_union</tt>, <tt>set_intersection</tt>,
<tt>set_difference</tt>, and <tt>set_symmetric_difference</tt>.  Each
of these algorithms takes two sorted ranges as inputs, and writes the
output of the appropriate set operation to an output range.  The elements
in the output range are sorted.
</p>

<p>
The ordinary mathematical definitions are generalized so that they
apply to ranges containing multiple copies of a given element.  Two
elements are considered to be "the same" if, according to an
ordering relation provided by the user, neither one is less than the
other.  So, for example, if one input range contains five copies of an
element and another contains three, the output range of <tt>set_union</tt>
will contain five copies, the output range of
<tt>set_intersection</tt> will contain three, the output range of
<tt>set_difference</tt> will contain two, and the output range of
<tt>set_symmetric_difference</tt> will contain two.
</p>

<p>
Because two elements can be "the same" for the purposes
of these set algorithms, without being identical in other respects
(consider, for example, strings under case-insensitive comparison),
this raises a number of unanswered questions:
</p>

<ul>
<li>If we're copying an element that's present in both of the
input ranges, which one do we copy it from?</li>
<li>If there are <i>n</i> copies of an element in the relevant
input range, and the output range will contain fewer copies (say
<i>m</i>) which ones do we choose?  The first <i>m</i>, or the last
<i>m</i>, or something else?</li>
<li>Are these operations stable?  That is, does a run of equivalent
elements appear in the output range in the same order as as it
appeared in the input range(s)?</li>
</ul>

<p>
The standard should either answer these questions, or explicitly
say that the answers are unspecified.  I prefer the former option,
since, as far as I know, all existing implementations behave the
same way.
</p>

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

<p>Add the following to the end of 25.3.5.2 <a href="lib-algorithms.html#lib.set.union"> [lib.set.union]</a> paragraph 5:</p>
<blockquote>
If [first1, last1) contains <i>m</i> elements that are equivalent to
each other and [first2, last2) contains <i>n</i> elements that are
equivalent to them, then max(<i>m</i>, <i>n</i>) of these elements
will be copied to the output range: all <i>m</i> of these elements
from [first1, last1), and the last max(<i>n-m</i>, 0) of them from
[first2, last2), in that order.
</blockquote>

<p>Add the following to the end of 25.3.5.3 <a href="lib-algorithms.html#lib.set.intersection"> [lib.set.intersection]</a> paragraph 5:</p>
<blockquote>
If [first1, last1) contains <i>m</i> elements that are equivalent to each
other and [first2, last2) contains <i>n</i> elements that are
equivalent to them, the first min(<i>m</i>, <i>n</i>) of those 
elements from [first1, last1) are copied to the output range.
</blockquote>

<p>Add a new paragraph, <b>Notes</b>, after 25.3.5.4 <a href="lib-algorithms.html#lib.set.difference"> [lib.set.difference]</a>
paragraph 4:</p>
<blockquote>
If [first1, last1) contains <i>m</i> elements that are equivalent to each
other and [first2, last2) contains <i>n</i> elements that are
equivalent to them, the last max(<i>m-n</i>, 0) elements from 
[first1, last1) are copied to the output range.
</blockquote>

<p>Add a new paragraph, <b>Notes</b>, after 25.3.5.5 <a href="lib-algorithms.html#lib.set.symmetric.difference"> [lib.set.symmetric.difference]</a>
paragraph 4:</p>
<blockquote>
If [first1, last1) contains <i>m</i> elements that are equivalent to
each other and [first2, last2) contains <i>n</i> elements that are
equivalent to them, then |<i>m - n</i>| of those elements will be
copied to the output range: the last <i>m - n</i> of these elements
from [first1, last1) if <i>m</i> &gt; <i>n</i>, and the last <i>n -
m</i> of these elements from [first2, last2) if <i>m</i> &lt; <i>n</i>.
</blockquote>

<p><i>[Santa Cruz: it's believed that this language is clearer than
  what's in the Standard.  However, it's also believed that the
  Standard may already make these guarantees (although not quite in
  these words).  Bill and Howard will check and see whether they think
  that some or all of these changes may be redundant.  If so, we may
  close this issue as NAD.]</i></p>

<p><b>Rationale:</b></p>
<p>For simple cases, these descriptions are equivalent to what's
  already in the Standard.  For more complicated cases, they describe
  the behavior of existing implementations.</p>
<hr>
<a name="292"><h3>292.&nbsp;effects of a.copyfmt (a)</h3></a><p><b>Section:</b>&nbsp;27.4.4.2 <a href="lib-iostreams.html#lib.basic.ios.members"> [lib.basic.ios.members]</a>&nbsp; <b>Status:</b>&nbsp;<a href="lwg-active.html#WP">WP</a>&nbsp; <b>Submitter:</b>&nbsp;Martin Sebor&nbsp; <b>Date:</b>&nbsp;05 Jan 2001</p>
<p>The Effects clause of the member function <tt>copyfmt()</tt> in
27.4.4.2, p15 doesn't consider the case where the left-hand side
argument is identical to the argument on the right-hand side, that is
<tt>(this == &amp;rhs)</tt>.  If the two arguments are identical there
is no need to copy any of the data members or call any callbacks
registered with <tt>register_callback()</tt>.  Also, as Howard Hinnant
points out in message c++std-lib-8149 it appears to be incorrect to
allow the object to fire <tt>erase_event</tt> followed by
<tt>copyfmt_event</tt> since the callback handling the latter event
may inadvertently attempt to access memory freed by the former.
</p>
<p><b>Proposed resolution:</b></p>
<p>Change the Effects clause in 27.4.4.2, p15 from</p>

<blockquote>
<b>-15- Effects:</b>Assigns to the member objects of <tt>*this</tt>
the corresponding member objects of <tt>rhs</tt>, except that...
</blockquote>

<p>to</p>

<blockquote>
<b>-15- Effects:</b>If <tt>(this == &amp;rhs)</tt> does nothing. Otherwise
assigns to the member objects of <tt>*this</tt> the corresponding member
objects of <tt>rhs</tt>, except that...
</blockquote>
<hr>
<a name="295"><h3>295.&nbsp;Is abs defined in &lt;cmath&gt;?</h3></a><p><b>Section:</b>&nbsp;26.5 <a href="lib-numerics.html#lib.c.math"> [lib.c.math]</a>&nbsp; <b>Status:</b>&nbsp;<a href="lwg-active.html#WP">WP</a>&nbsp; <b>Submitter:</b>&nbsp;Jens Maurer&nbsp; <b>Date:</b>&nbsp;12 Jan 2001</p>
<p>
Table 80 lists the contents of the &lt;cmath&gt; header.  It does not
list <tt>abs()</tt>.  However, 26.5, paragraph 6, which lists added 
signatures present in &lt;cmath&gt;, does say that several overloads
of <tt>abs()</tt> should be defined in &lt;cmath&gt;.
</p>
<p><b>Proposed resolution:</b></p>
<p>
Add <tt>abs</tt> to Table 80.  Also, remove the parenthetical list
of functions "(abs(), div(), rand(), srand())" from 26.5 <a href="lib-numerics.html#lib.c.math"> [lib.c.math]</a>,
paragraph 1.
</p>

<p><i>[Copenhagen: Modified proposed resolution so that it also gets
rid of that vestigial list of functions in paragraph 1.]</i></p>

<p><b>Rationale:</b></p>
<p>All this DR does is fix a typo; it's uncontroversial.  A 
separate question is whether we're doing the right thing in 
putting some overloads in &lt;cmath&gt; that we aren't also 
putting in &lt;cstdlib&gt;.  That's issue <a href="lwg-closed.html#323">323</a>.</p>
<hr>
<a name="297"><h3>297.&nbsp;const_mem_fun_t&lt;&gt;::argument_type should be const T*</h3></a><p><b>Section:</b>&nbsp;20.3.8 <a href="lib-utilities.html#lib.member.pointer.adaptors"> [lib.member.pointer.adaptors]</a>&nbsp; <b>Status:</b>&nbsp;<a href="lwg-active.html#WP">WP</a>&nbsp; <b>Submitter:</b>&nbsp;Martin Sebor&nbsp; <b>Date:</b>&nbsp;6 Jan 2001</p>
<p>The class templates <tt>const_mem_fun_t</tt> in 20.3.8, p8 and
<tt>const_mem_fun1_t</tt>
in 20.3.8, p9 derive from <tt>unary_function&lt;T*, S&gt;</tt>, and
<tt>binary_function&lt;T*,
A, S&gt;</tt>, respectively. Consequently, their <tt>argument_type</tt>, and
<tt>first_argument_type</tt>
members, respectively, are both defined to be <tt>T*</tt> (non-const).
However, their function call member operator takes a <tt>const T*</tt>
argument. It is my opinion that <tt>argument_type</tt> should be <tt>const
T*</tt> instead, so that one can easily refer to it in generic code. The
example below derived from existing code fails to compile due to the
discrepancy:
</p>

<p><tt>template &lt;class T&gt;</tt>
<br><tt>void foo (typename T::argument_type arg)&nbsp;&nbsp; // #1</tt>
<br><tt>{</tt>
<br><tt>&nbsp;&nbsp;&nbsp; typename T::result_type (T::*pf) (typename
T::argument_type)
const =&nbsp;&nbsp; // #2</tt>
<br><tt>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; &amp;T::operator();</tt>
<br><tt>}</tt>
</p>

<p><tt>struct X { /* ... */ };</tt></p>

<p><tt>int main ()</tt>
<br><tt>{</tt>
<br><tt>&nbsp;&nbsp;&nbsp; const X x;</tt>
<br><tt>&nbsp;&nbsp;&nbsp; foo&lt;std::const_mem_fun_t&lt;void, X&gt;
&gt;(&amp;x);&nbsp;&nbsp;
// #3</tt>
<br><tt>}</tt>
</p>

<p>#1 <tt>foo()</tt> takes a plain unqualified <tt>X*</tt> as an argument
<br>#2 the type of the pointer is incompatible with the type of the member
function
<br>#3 the address of a constant being passed to a function taking a non-const
<tt>X*</tt>
</p>
<p><b>Proposed resolution:</b></p>
<p>Replace the top portion of the definition of the class template
const_mem_fun_t in 20.3.8, p8
</p>
<p><tt>template &lt;class S, class T&gt; class const_mem_fun_t</tt>
<br><tt>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; : public
unary_function&lt;T*, S&gt; {</tt>
</p>
<p>with</p>
<p><tt>template &lt;class S, class T&gt; class const_mem_fun_t</tt>
<br><tt>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; : public
unary_function&lt;<b>const</b> T*, S&gt; {</tt>
</p>
<p>Also replace the top portion of the definition of the class template
const_mem_fun1_t in 20.3.8, p9</p>
<p><tt>template &lt;class S, class T, class A&gt; class const_mem_fun1_t</tt>
<br><tt>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; : public
binary_function&lt;T*, A, S&gt; {</tt>
</p>
<p>with</p>
<p><tt>template &lt;class S, class T, class A&gt; class const_mem_fun1_t</tt>
<br><tt>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; : public
binary_function&lt;<b>const</b> T*, A, S&gt; {</tt>
</p>
<p><b>Rationale:</b></p>
<p>This is simply a contradiction: the <tt>argument_type</tt> typedef,
and the argument type itself, are not the same.</p>
<hr>
<a name="298"><h3>298.&nbsp;::operator delete[] requirement incorrect/insufficient</h3></a><p><b>Section:</b>&nbsp;18.4.1.2 <a href="lib-support.html#lib.new.delete.array"> [lib.new.delete.array]</a>&nbsp; <b>Status:</b>&nbsp;<a href="lwg-active.html#WP">WP</a>&nbsp; <b>Submitter:</b>&nbsp;John A. Pedretti&nbsp; <b>Date:</b>&nbsp;10 Jan 2001</p>
<p>
The default behavior of <tt>operator delete[]</tt> described in 18.4.1.2, p12 -
namely that for non-null value of <i>ptr</i>, the operator reclaims storage
allocated by the earlier call to the default <tt>operator new[]</tt> - is not
correct in all cases. Since the specified <tt>operator new[]</tt> default
behavior is to call <tt>operator new</tt> (18.4.1.2, p4, p8), which can be
replaced, along with <tt>operator delete</tt>, by the user, to implement their
own memory management, the specified default behavior of<tt> operator
delete[]</tt> must be to call <tt>operator delete</tt>.
</p>
<p><b>Proposed resolution:</b></p>
<p>Change 18.4.1.2, p12 from</p>
<blockquote>
<b>-12-</b> <b>Default behavior:</b>
<ul>
<li>
For a null value of <i><tt>ptr</tt></i> , does nothing.
</li>
<li>
Any other value of <i><tt>ptr</tt></i> shall be a value returned
earlier by a call to the default <tt>operator new[](std::size_t)</tt>.
[Footnote: The value must not have been invalidated by an intervening
call to <tt>operator delete[](void*)</tt> (17.4.3.7 <a href="lib-intro.html#lib.res.on.arguments"> [lib.res.on.arguments]</a>).
--- end footnote]
For such a non-null value of <i><tt>ptr</tt></i> , reclaims storage
allocated by the earlier call to the default <tt>operator new[]</tt>.
</li>
</ul>
</blockquote>

<p>to</p>

<blockquote>
<b>-12-</b> <b>Default behavior: </b>Calls <tt>operator
delete(</tt><i>ptr</i>)
or <tt>operator delete(<i>ptr</i>, std::nothrow)</tt> respectively.
</blockquote>
<p>and expunge paragraph 13.</p>
<hr>
<a name="300"><h3>300.&nbsp;list::merge() specification incomplete</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#WP">WP</a>&nbsp; <b>Submitter:</b>&nbsp;John Pedretti&nbsp; <b>Date:</b>&nbsp;23 Jan 2001</p>
<p>
The "Effects" clause for list::merge() (23.2.2.4, p23)
appears to be incomplete: it doesn't cover the case where the argument
list is identical to *this (i.e., this == &amp;x). The requirement in the
note in p24 (below) is that x be empty after the merge which is surely
unintended in this case.
</p>
<p><b>Proposed resolution:</b></p>
<p>In 23.2.2.4 <a href="lib-containers.html#lib.list.ops"> [lib.list.ops]</a>, replace paragraps 23-25 with:</p>
<blockquote>
<p>
23 Effects: if (&amp;x == this) does nothing; otherwise, merges the two
sorted ranges [begin(), end()) and [x.begin(), x.end()).  The result
is a range in which the elements will be sorted in non-decreasing
order according to the ordering defined by comp; that is, for every
iterator i in the range other than the first, the condition comp(*i,
*(i - 1)) will be false.
</p>

<p>
24 Notes: Stable: if (&amp;x != this), then for equivalent elements in the
two original ranges, the elements from the original range [begin(),
end()) always precede the elements from the original range [x.begin(),
x.end()).  If (&amp;x != this) the range [x.begin(), x.end()) is empty
after the merge.
</p>

<p>
25 Complexity: At most size() + x.size() - 1 applications of comp if
(&amp;x !  = this); otherwise, no applications of comp are performed.  If
an exception is thrown other than by a comparison there are no
effects.
</p>

</blockquote>

<p><i>[Copenhagen: The original proposed resolution did not fix all of
the problems in 23.2.2.4 <a href="lib-containers.html#lib.list.ops"> [lib.list.ops]</a>, p22-25.  Three different
paragraphs (23, 24, 25) describe the effects of <tt>merge</tt>.
Changing p23, without changing the other two, appears to introduce
contradictions.  Additionally, "merges the argument list into the
list" is excessively vague.]</i></p>

<p><i>[Post-Cura&ccedil;ao: Robert Klarer provided new wording.]</i></p>

<hr>
<a name="301"><h3>301.&nbsp;basic_string template ctor effects clause omits allocator argument</h3></a><p><b>Section:</b>&nbsp;21.3.1 <a href="lib-strings.html#lib.string.cons"> [lib.string.cons]</a>&nbsp; <b>Status:</b>&nbsp;<a href="lwg-active.html#WP">WP</a>&nbsp; <b>Submitter:</b>&nbsp;Martin Sebor&nbsp; <b>Date:</b>&nbsp;27 Jan 2001</p>
<p>
The effects clause for the basic_string template ctor in 21.3.1, p15
leaves out the third argument of type Allocator. I believe this to be
a mistake.
</p>
<p><b>Proposed resolution:</b></p>
<p>Replace</p>

<blockquote>
    <p><b>-15- Effects:</b> If <i><tt>InputIterator</tt></i> is an integral
    type, equivalent to</p>

    <blockquote><tt>basic_string(static_cast&lt;size_type&gt;(begin),
    static_cast&lt;value_type&gt;(end))</tt></blockquote>
</blockquote>

<p>with</p>

<blockquote>
    <p><b>-15- Effects:</b> If <i><tt>InputIterator</tt></i> is an integral
    type, equivalent to</p>

    <blockquote><tt>basic_string(static_cast&lt;size_type&gt;(begin),
    static_cast&lt;value_type&gt;(end), <b>a</b>)</tt></blockquote>
</blockquote>
<hr>
<a name="303"><h3>303.&nbsp;Bitset input operator underspecified</h3></a><p><b>Section:</b>&nbsp;23.3.5.3 <a href="lib-containers.html#lib.bitset.operators"> [lib.bitset.operators]</a>&nbsp; <b>Status:</b>&nbsp;<a href="lwg-active.html#WP">WP</a>&nbsp; <b>Submitter:</b>&nbsp;Matt Austern&nbsp; <b>Date:</b>&nbsp;5 Feb 2001</p>
<p>
In 23.3.5.3, we are told that <tt>bitset</tt>'s input operator
"Extracts up to <i>N</i> (single-byte) characters from
<i>is</i>.", where <i>is</i> is a stream of type
<tt>basic_istream&lt;charT, traits&gt;</tt>.
</p>

<p>
The standard does not say what it means to extract single byte
characters from a stream whose character type, <tt>charT</tt>, is in
general not a single-byte character type.  Existing implementations
differ.
</p>

<p>
A reasonable solution will probably involve <tt>widen()</tt> and/or
<tt>narrow()</tt>, since they are the supplied mechanism for
converting a single character between <tt>char</tt> and 
arbitrary <tt>charT</tt>.
</p>

<p>Narrowing the input characters is not the same as widening the
literals <tt>'0'</tt> and <tt>'1'</tt>, because there may be some
locales in which more than one wide character maps to the narrow
character <tt>'0'</tt>.  Narrowing means that alternate
representations may be used for bitset input, widening means that
they may not be.</p>

<p>Note that for numeric input, <tt>num_get&lt;&gt;</tt>
(22.2.2.1.2/8) compares input characters to widened version of narrow
character literals.</p>

<p>From Pete Becker, in c++std-lib-8224:</p>
<blockquote>
<p>
Different writing systems can have different representations for the
digits that represent 0 and 1. For example, in the Unicode representation
of the Devanagari script (used in many of the Indic languages) the digit 0
is 0x0966, and the digit 1 is 0x0967. Calling narrow would translate those
into '0' and '1'. But Unicode also provides the ASCII values 0x0030 and
0x0031 for for the Latin representations of '0' and '1', as well as code
points for the same numeric values in several other scripts (Tamil has no
character for 0, but does have the digits 1-9), and any of these values
would also be narrowed to '0' and '1'.
</p>

<p>...</p>

<p>
It's fairly common to intermix both native and Latin
representations of numbers in a document. So I think the rule has to be
that if a wide character represents a digit whose value is 0 then the bit
should be cleared; if it represents a digit whose value is 1 then the bit
should be set; otherwise throw an exception. So in a Devanagari locale,
both 0x0966 and 0x0030 would clear the bit, and both 0x0967 and 0x0031
would set it. Widen can't do that. It would pick one of those two values,
and exclude the other one.
</p>

</blockquote>

<p>From Jens Maurer, in c++std-lib-8233:</p>

<blockquote>
<p>
Whatever we decide, I would find it most surprising if
bitset conversion worked differently from int conversion
with regard to alternate local representations of
numbers.
</p>

<p>Thus, I think the options are:</p>
<ul>
 <li> Have a new defect issue for 22.2.2.1.2/8 so that it will
require the use of narrow().</li>

 <li> Have a defect issue for bitset() which describes clearly
that widen() is to be used.</li>
</ul>
</blockquote>
<p><b>Proposed resolution:</b></p>

    <p>Replace the first two sentences of paragraph 5 with:</p>

    <blockquote>
    Extracts up to <i>N</i> characters from <i>is</i>. Stores these
    characters in a temporary object <i>str</i> of type
    <tt>basic_string&lt;charT, traits&gt;</tt>, then evaluates the
    expression <tt><i>x</i> = bitset&lt;N&gt;(<i>str</i>)</tt>.
    </blockquote>

    <p>Replace the third bullet item in paragraph 5 with:</p>
    <ul><li>
    the next input character is neither <tt><i>is</i>.widen(0)</tt>
    nor <tt><i>is</i>.widen(1)</tt> (in which case the input character
    is not extracted).
    </li></ul>

<p><b>Rationale:</b></p>
<p>Input for <tt>bitset</tt> should work the same way as numeric
input.  Using <tt>widen</tt> does mean that alternative digit
representations will not be recognized, but this was a known 
consequence of the design choice.</p>
<hr>
<a name="305"><h3>305.&nbsp;Default behavior of codecvt&lt;wchar_t, char, mbstate_t&gt;::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#WP">WP</a>&nbsp; <b>Submitter:</b>&nbsp;Howard Hinnant&nbsp; <b>Date:</b>&nbsp;24 Jan 2001</p>
<p>22.2.1.5/3 introduces codecvt in part with:</p>

<blockquote>
  codecvt&lt;wchar_t,char,mbstate_t&gt; converts between the native
  character sets for tiny and wide characters. Instantiations on
  mbstate_t perform conversion between encodings known to the library
  implementor.
</blockquote>

<p>But 22.2.1.5.2/10 describes do_length in part with:</p>

<blockquote>
  ... codecvt&lt;wchar_t, char, mbstate_t&gt; ... return(s) the lesser of max and 
  (from_end-from).
</blockquote>

<p>
The semantics of do_in and do_length are linked.  What one does must
be consistent with what the other does.  22.2.1.5/3 leads me to
believe that the vendor is allowed to choose the algorithm that
codecvt&lt;wchar_t,char,mbstate_t&gt;::do_in performs so that it makes
his customers happy on a given platform.  But 22.2.1.5.2/10 explicitly
says what codecvt&lt;wchar_t,char,mbstate_t&gt;::do_length must
return.  And thus indirectly specifies the algorithm that
codecvt&lt;wchar_t,char,mbstate_t&gt;::do_in must perform.  I believe
that this is not what was intended and is a defect.
</p>

<p>Discussion from the -lib reflector:

<br>This proposal would have the effect of making the semantics of
all of the virtual functions in <tt>codecvt&lt;wchar_t, char,
mbstate_t&gt;</tt> implementation specified.  Is that what we want, or
do we want to mandate specific behavior for the base class virtuals
and leave the implementation specified behavior for the codecvt_byname
derived class?  The tradeoff is that former allows implementors to
write a base class that actually does something useful, while the
latter gives users a way to get known and specified---albeit
useless---behavior, and is consistent with the way the standard
handles other facets.  It is not clear what the original intention
was.</p>

<p>
Nathan has suggest a compromise: a character that is a widened version
of the characters in the basic execution character set must be
converted to a one-byte sequence, but there is no such requirement
for characters that are not part of the basic execution character set.
</p>
<p><b>Proposed resolution:</b></p>
<p>
Change 22.2.1.5.2/5 from:
</p>
<p>
The instantiations required in Table 51 (lib.locale.category), namely
codecvt&lt;wchar_t,char,mbstate_t&gt; and
codecvt&lt;char,char,mbstate_t&gt;, store no characters. Stores no more
than (to_limit-to) destination elements. It always leaves the to_next
pointer pointing one beyond the last element successfully stored.
</p>
<p>
to:
</p>
<p>
Stores no more than (to_limit-to) destination elements, and leaves the
to_next pointer pointing one beyond the last element successfully
stored.  codecvt&lt;char,char,mbstate_t&gt; stores no characters.
</p>

<p>Change 22.2.1.5.2/10 from:</p>

<blockquote>
-10- Returns: (from_next-from) where from_next is the largest value in
the range [from,from_end] such that the sequence of values in the
range [from,from_next) represents max or fewer valid complete
characters of type internT. The instantiations required in Table 51
(21.1.1.1.1), namely codecvt&lt;wchar_t, char, mbstate_t&gt; and
codecvt&lt;char, char, mbstate_t&gt;, return the lesser of max and
(from_end-from).
</blockquote>

<p>to:</p>

<blockquote>
-10- Returns: (from_next-from) where from_next is the largest value in 
the range [from,from_end] such that the sequence of values in the range 
[from,from_next) represents max or fewer valid complete characters of 
type internT. The instantiation codecvt&lt;char, char, mbstate_t&gt; returns 
the lesser of max and (from_end-from). 
</blockquote>

<p><i>[Redmond: Nathan suggested an alternative resolution: same as
above, but require that, in the default encoding, a character from the
basic execution character set would map to a single external
character.  The straw poll was 8-1 in favor of the proposed
resolution.]</i></p>

<p><b>Rationale:</b></p>
<p>The default encoding should be whatever users of a given platform
would expect to be the most natural.  This varies from platform to
platform.  In many cases there is a preexisting C library, and users
would expect the default encoding to be whatever C uses in the default
"C" locale.  We could impose a guarantee like the one Nathan suggested
(a character from the basic execution character set must map to a
single external character), but this would rule out important
encodings that are in common use: it would rule out JIS, for
example, and it would rule out a fixed-width encoding of UCS-4.</p>

<p><i>[Cura&ccedil;ao: fixed rationale typo at the request of Ichiro Koshida;
"shift-JIS" changed to "JIS".]</i></p>

<hr>
<a name="306"><h3>306.&nbsp;offsetof macro and non-POD types</h3></a><p><b>Section:</b>&nbsp;18.1 <a href="lib-support.html#lib.support.types"> [lib.support.types]</a>&nbsp; <b>Status:</b>&nbsp;<a href="lwg-active.html#WP">WP</a>&nbsp; <b>Submitter:</b>&nbsp;Steve Clamage&nbsp; <b>Date:</b>&nbsp;21 Feb 2001</p> 
<p>Spliced together from reflector messages c++std-lib-8294 and -8295:</p>

<p>18.1, paragraph 5, reads: "The macro <tt>offsetof</tt>
accepts a restricted set of <i>type</i> arguments in this
International Standard. <i>type</i> shall be a POD structure or a POD
union (clause 9). The result of applying the offsetof macro to a field
that is a static data member or a function member is
undefined."</p>

<p>For the POD requirement, it doesn't say "no diagnostic
required" or "undefined behavior". I read 1.4 <a href="intro.html#intro.compliance"> [intro.compliance]</a>, paragraph 1, to mean that a diagnostic is required.
It's not clear whether this requirement was intended.  While it's
possible to provide such a diagnostic, the extra complication doesn't
seem to add any value.
</p>
<p><b>Proposed resolution:</b></p>
<p>Change 18.1, paragraph 5, to "If <i>type</i> is not a POD
structure or a POD union the results are undefined."</p>

<p><i>[Copenhagen: straw poll was 7-4 in favor.  It was generally
agreed that requiring a diagnostic was inadvertent, but some LWG
members thought that diagnostics should be required whenever
possible.]</i></p>

<hr>
<a name="307"><h3>307.&nbsp;Lack of reference typedefs in container adaptors</h3></a><p><b>Section:</b>&nbsp;23.2.3 <a href="lib-containers.html#lib.container.adaptors"> [lib.container.adaptors]</a>&nbsp; <b>Status:</b>&nbsp;<a href="lwg-active.html#WP">WP</a>&nbsp; <b>Submitter:</b>&nbsp;Howard Hinnant&nbsp; <b>Date:</b>&nbsp;13 Mar 2001</p>

<p>From reflector message c++std-lib-8330.  See also lib-8317.</p>

<p>
The standard is currently inconsistent in 23.2.3.2 <a href="lib-containers.html#lib.priority.queue"> [lib.priority.queue]</a>
paragraph 1 and 23.2.3.3 <a href="lib-containers.html#lib.stack"> [lib.stack]</a> paragraph 1.
23.2.3.3/1, for example, says:
</p>

<blockquote>
-1- Any sequence supporting operations back(), push_back() and pop_back() 
can be used to instantiate stack. In particular, vector (lib.vector), list 
(lib.list) and deque (lib.deque) can be used. 
</blockquote>

<p>But this is false: vector&lt;bool&gt; can not be used, because the
container adaptors return a T&amp; rather than using the underlying
container's reference type.</p>

<p>This is a contradiction that can be fixed by:</p>

<ol>
<li>Modifying these paragraphs to say that vector&lt;bool&gt;
    is an exception.</li>
<li>Removing the vector&lt;bool&gt; specialization.</li>
<li>Changing the return types of stack and priority_queue to use 
    reference typedef's.</li>
</ol>

<p>
I propose 3.  This does not preclude option 2 if we choose to do it
later (see issue <a href="lwg-active.html#96">96</a>); the issues are independent.  Option
3 offers a small step towards support for proxied containers.  This
small step fixes a current contradiction, is easy for vendors to
implement, is already implemented in at least one popular lib, and
does not break any code.
</p>

<p><b>Proposed resolution:</b></p>
<p>Summary: Add reference and const_reference typedefs to queue,
priority_queue and stack.  Change return types of "value_type&amp;" to
"reference".  Change return types of "const value_type&amp;" to
"const_reference".  Details:</p>

<p>Change 23.2.3.1/1 from:</p>

<pre>
  namespace std {
    template &lt;class T, class Container = deque&lt;T&gt; &gt;
    class queue {
    public:
      typedef typename Container::value_type            value_type;
      typedef typename Container::size_type             size_type;
      typedef          Container                        container_type;
    protected:
      Container c;

    public:
      explicit queue(const Container&amp; = Container());

      bool      empty() const             { return c.empty(); }
      size_type size()  const             { return c.size(); }
      value_type&amp;       front()           { return c.front(); }
      const value_type&amp; front() const     { return c.front(); }
      value_type&amp;       back()            { return c.back(); }
      const value_type&amp; back() const      { return c.back(); }
      void push(const value_type&amp; x)      { c.push_back(x); }
      void pop()                          { c.pop_front(); }
    };
</pre>

<p>to:</p>

<pre>
  namespace std {
    template &lt;class T, class Container = deque&lt;T&gt; &gt;
    class queue {
    public:
      typedef typename Container::value_type            value_type;
      typedef typename Container::reference             reference;
      typedef typename Container::const_reference       const_reference;
      typedef typename Container::value_type            value_type;
      typedef typename Container::size_type             size_type;
      typedef          Container                        container_type;
    protected:
      Container c;

    public:
      explicit queue(const Container&amp; = Container());

      bool      empty() const             { return c.empty(); }
      size_type size()  const             { return c.size(); }
      reference         front()           { return c.front(); }
      const_reference   front() const     { return c.front(); }
      reference         back()            { return c.back(); }
      const_reference   back() const      { return c.back(); }
      void push(const value_type&amp; x)      { c.push_back(x); }
      void pop()                          { c.pop_front(); }
    };
</pre>

<p>Change 23.2.3.2/1 from:</p>

<pre>
  namespace std {
    template &lt;class T, class Container = vector&lt;T&gt;,
              class Compare = less&lt;typename Container::value_type&gt; &gt;
    class priority_queue {
    public:
      typedef typename Container::value_type            value_type;
      typedef typename Container::size_type             size_type;
      typedef          Container                        container_type;
    protected:
      Container c;
      Compare comp;

    public:
      explicit priority_queue(const Compare&amp; x = Compare(),
                              const Container&amp; = Container());
      template &lt;class InputIterator&gt;
        priority_queue(InputIterator first, InputIterator last,
                       const Compare&amp; x = Compare(),
                       const Container&amp; = Container());

      bool      empty() const       { return c.empty(); }
      size_type size()  const       { return c.size(); }
      const value_type&amp; top() const { return c.front(); }
      void push(const value_type&amp; x);
      void pop();
    };
                                  //  no equality is provided
  }
</pre>

<p>to:</p>

<pre>
  namespace std {
    template &lt;class T, class Container = vector&lt;T&gt;,
              class Compare = less&lt;typename Container::value_type&gt; &gt;
    class priority_queue {
    public:
      typedef typename Container::value_type            value_type;
      typedef typename Container::reference             reference;
      typedef typename Container::const_reference       const_reference;
      typedef typename Container::size_type             size_type;
      typedef          Container                        container_type;
    protected:
      Container c;
      Compare comp;

    public:
      explicit priority_queue(const Compare&amp; x = Compare(),
                              const Container&amp; = Container());
      template &lt;class InputIterator&gt;
        priority_queue(InputIterator first, InputIterator last,
                       const Compare&amp; x = Compare(),
                       const Container&amp; = Container());

      bool      empty() const       { return c.empty(); }
      size_type size()  const       { return c.size(); }
      const_reference   top() const { return c.front(); }
      void push(const value_type&amp; x);
      void pop();
    };
                                  //  no equality is provided
  }
</pre>

<p>And change 23.2.3.3/1 from:</p>

<pre>
  namespace std {
    template &lt;class T, class Container = deque&lt;T&gt; &gt;
    class stack {
    public:
      typedef typename Container::value_type            value_type;
      typedef typename Container::size_type             size_type;
      typedef          Container                        container_type;
    protected:
      Container c;

    public:
      explicit stack(const Container&amp; = Container());

      bool      empty() const             { return c.empty(); }
      size_type size()  const             { return c.size(); }
      value_type&amp;       top()             { return c.back(); }
      const value_type&amp; top() const       { return c.back(); }
      void push(const value_type&amp; x)      { c.push_back(x); }
      void pop()                          { c.pop_back(); }
    };

    template &lt;class T, class Container&gt;
      bool operator==(const stack&lt;T, Container&gt;&amp; x,
                      const stack&lt;T, Container&gt;&amp; y);
    template &lt;class T, class Container&gt;
      bool operator&lt; (const stack&lt;T, Container&gt;&amp; x,
                      const stack&lt;T, Container&gt;&amp; y);
    template &lt;class T, class Container&gt;
      bool operator!=(const stack&lt;T, Container&gt;&amp; x,
                      const stack&lt;T, Container&gt;&amp; y);
    template &lt;class T, class Container&gt;
      bool operator&gt; (const stack&lt;T, Container&gt;&amp; x,
                      const stack&lt;T, Container&gt;&amp; y);
    template &lt;class T, class Container&gt;
      bool operator&gt;=(const stack&lt;T, Container&gt;&amp; x,
                      const stack&lt;T, Container&gt;&amp; y);
    template &lt;class T, class Container&gt;
      bool operator&lt;=(const stack&lt;T, Container&gt;&amp; x,
                      const stack&lt;T, Container&gt;&amp; y);
  }
</pre>

<p>to:</p>

<pre>
  namespace std {
    template &lt;class T, class Container = deque&lt;T&gt; &gt;
    class stack {
    public:
      typedef typename Container::value_type            value_type;
      typedef typename Container::reference             reference;
      typedef typename Container::const_reference       const_reference;
      typedef typename Container::size_type             size_type;
      typedef          Container                        container_type;
    protected:
      Container c;

    public:
      explicit stack(const Container&amp; = Container());

      bool      empty() const             { return c.empty(); }
      size_type size()  const             { return c.size(); }
      reference         top()             { return c.back(); }
      const_reference   top() const       { return c.back(); }
      void push(const value_type&amp; x)      { c.push_back(x); }
      void pop()                          { c.pop_back(); }
    };

    template &lt;class T, class Container&gt;
      bool operator==(const stack&lt;T, Container&gt;&amp; x,
                      const stack&lt;T, Container&gt;&amp; y);
    template &lt;class T, class Container&gt;
      bool operator&lt; (const stack&lt;T, Container&gt;&amp; x,
                      const stack&lt;T, Container&gt;&amp; y);
    template &lt;class T, class Container&gt;
      bool operator!=(const stack&lt;T, Container&gt;&amp; x,
                      const stack&lt;T, Container&gt;&amp; y);
    template &lt;class T, class Container&gt;
      bool operator&gt; (const stack&lt;T, Container&gt;&amp; x,
                      const stack&lt;T, Container&gt;&amp; y);
    template &lt;class T, class Container&gt;
      bool operator&gt;=(const stack&lt;T, Container&gt;&amp; x,
                      const stack&lt;T, Container&gt;&amp; y);
    template &lt;class T, class Container&gt;
      bool operator&lt;=(const stack&lt;T, Container&gt;&amp; x,
                      const stack&lt;T, Container&gt;&amp; y);
  }
</pre>

<p><i>[Copenhagen: This change was discussed before the IS was released
and it was deliberately not adopted.  Nevertheless, the LWG believes
(straw poll: 10-2) that it is a genuine defect.]</i></p>

<hr>
<a name="308"><h3>308.&nbsp;Table 82 mentions unrelated headers</h3></a><p><b>Section:</b>&nbsp;27 <a href="lib-iostreams.html#lib.input.output"> [lib.input.output]</a>&nbsp; <b>Status:</b>&nbsp;<a href="lwg-active.html#WP">WP</a>&nbsp; <b>Submitter:</b>&nbsp;Martin Sebor&nbsp; <b>Date:</b>&nbsp;15 Mar 2001</p>
<p>
Table 82 in section 27 mentions the header &lt;cstdlib&gt; for String
streams (27.7 <a href="lib-iostreams.html#lib.string.streams"> [lib.string.streams]</a>) and the headers &lt;cstdio&gt; and
&lt;cwchar&gt; for File streams (27.8 <a href="lib-iostreams.html#lib.file.streams"> [lib.file.streams]</a>). It's not clear
why these headers are mentioned in this context since they do not
define any of the library entities described by the
subclauses. According to 17.4.1.1 <a href="lib-intro.html#lib.contents"> [lib.contents]</a>, only such headers
are to be listed in the summary.
</p>
<p><b>Proposed resolution:</b></p>
<p>Remove &lt;cstdlib&gt; and &lt;cwchar&gt; from
Table 82.</p>

<p><i>[Copenhagen: changed the proposed resolution slightly.  The
original proposed resolution also said to remove &lt;cstdio&gt; from
Table 82.  However, &lt;cstdio&gt; is mentioned several times within
section 27.8 <a href="lib-iostreams.html#lib.file.streams"> [lib.file.streams]</a>, including 27.8.2 <a href="lib-iostreams.html#lib.c.files"> [lib.c.files]</a>.]</i></p>

<hr>
<a name="310"><h3>310.&nbsp;Is errno a macro?</h3></a><p><b>Section:</b>&nbsp;17.4.1.2 <a href="lib-intro.html#lib.headers"> [lib.headers]</a>, 19.3 <a href="lib-diagnostics.html#lib.errno"> [lib.errno]</a>&nbsp; <b>Status:</b>&nbsp;<a href="lwg-active.html#WP">WP</a>&nbsp; <b>Submitter:</b>&nbsp;Steve Clamage&nbsp; <b>Date:</b>&nbsp;21 Mar 2001</p>
  <p>
  Exactly how should errno be declared in a conforming C++ header?
  </p>

  <p>
  The C standard says in 7.1.4 that it is unspecified whether errno is a
  macro or an identifier with external linkage.  In some implementations
  it can be either, depending on compile-time options.  (E.g., on
  Solaris in multi-threading mode, errno is a macro that expands to a
  function call, but is an extern int otherwise.  "Unspecified" allows
  such variability.)
  </p>

  <p>The C++ standard:</p>
  <ul>
  <li>17.4.1.2 says in a note that errno must be macro in C. (false)</li>
  <li>17.4.3.1.3 footnote 166 says errno is reserved as an external 
      name (true), and implies that it is an identifier.</li>
  <li>19.3 simply lists errno as a macro (by what reasoning?) and goes
      on to say that the contents of of C++ &lt;errno.h&gt; are the
      same as in C, begging the question.</li>
  <li>C.2, table 95 lists errno as a macro, without comment.</li>
  </ul>

  <p>I find no other references to errno.</p>

  <p>We should either explicitly say that errno must be a macro, even
  though it need not be a macro in C, or else explicitly leave it
  unspecified.  We also need to say something about namespace std. 
  A user who includes &lt;cerrno&gt; needs to know whether to write
  <tt>errno</tt>, or <tt>::errno</tt>, or <tt>std::errno</tt>, or
  else &lt;cerrno&gt; is useless.</p>

  <p>Two acceptable fixes:</p>
  <ul>
    <li><p>errno must be a macro. This is trivially satisfied by adding<br>
        &nbsp;&nbsp;#define errno (::std::errno)<br>
        to the headers if errno is not already a macro. You then always
        write errno without any scope qualification, and it always expands
        to a correct reference. Since it is always a macro, you know to
        avoid using errno as a local identifer.</p></li>
    <li><p>errno is in the global namespace. This fix is inferior, because
        ::errno is not guaranteed to be well-formed.</p></li>
  </ul>

  <p><i>[
    This issue was first raised in 1999, but it slipped through 
    the cracks.
  ]</i></p>
<p><b>Proposed resolution:</b></p>
  <p>Change the Note in section 17.4.1.2p5 from</p>

    <blockquote>
    Note: the names defined as macros in C include the following:
    assert, errno, offsetof, setjmp, va_arg, va_end, and va_start.
    </blockquote>

  <p>to</p>

    <blockquote>
    Note: the names defined as macros in C include the following:
    assert, offsetof, setjmp, va_arg, va_end, and va_start.
    </blockquote>

  <p>In section 19.3, change paragraph 2 from</p>

    <blockquote>
    The contents are the same as the Standard C library header
    &lt;errno.h&gt;.
    </blockquote>

  <p>to</p>

    <blockquote>
    The contents are the same as the Standard C library header 
    &lt;errno.h&gt;, except that errno shall be defined as a macro.
    </blockquote>
<p><b>Rationale:</b></p>
<p>C++ must not leave it up to the implementation to decide whether or
not a name is a macro; it must explicitly specify exactly which names
are required to be macros.  The only one that really works is for it
to be a macro.</p>

<p><i>[Cura&ccedil;ao: additional rationale added.]</i></p>

<hr>
<a name="311"><h3>311.&nbsp;Incorrect wording in basic_ostream class synopsis</h3></a><p><b>Section:</b>&nbsp;27.6.2.1 <a href="lib-iostreams.html#lib.ostream"> [lib.ostream]</a>&nbsp; <b>Status:</b>&nbsp;<a href="lwg-active.html#WP">WP</a>&nbsp; <b>Submitter:</b>&nbsp;Andy Sawyer&nbsp; <b>Date:</b>&nbsp;21 Mar 2001</p>

<p>In 27.6.2.1 <a href="lib-iostreams.html#lib.ostream"> [lib.ostream]</a>, the synopsis of class basic_ostream says:</p>

<pre>
  // partial specializationss
  template&lt;class traits&gt;
    basic_ostream&lt;char,traits&gt;&amp; operator&lt;&lt;( basic_ostream&lt;char,traits&gt;&amp;,
                                            const char * );
</pre>

<p>Problems:</p>
<ul>
<li>Too many 's's at the end of "specializationss" </li>
<li>This is an overload, not a partial specialization</li>
</ul>

<p><b>Proposed resolution:</b></p>
<p>In the synopsis in 27.6.2.1 <a href="lib-iostreams.html#lib.ostream"> [lib.ostream]</a>, remove the 
<i>// partial specializationss</i> comment.  Also remove the same 
comment (correctly spelled, but still incorrect) from the synopsis in 
27.6.2.5.4 <a href="lib-iostreams.html#lib.ostream.inserters.character"> [lib.ostream.inserters.character]</a>.
</p>

<p><i>[
Pre-Redmond: added 27.6.2.5.4 <a href="lib-iostreams.html#lib.ostream.inserters.character"> [lib.ostream.inserters.character]</a> because of Martin's
comment in c++std-lib-8939.
]</i></p>

<hr>
<a name="312"><h3>312.&nbsp;Table 27 is missing headers</h3></a><p><b>Section:</b>&nbsp;20 <a href="lib-utilities.html#lib.utilities"> [lib.utilities]</a>&nbsp; <b>Status:</b>&nbsp;<a href="lwg-active.html#WP">WP</a>&nbsp; <b>Submitter:</b>&nbsp;Martin Sebor&nbsp; <b>Date:</b>&nbsp;29 Mar 2001</p>
<p>Table 27 in section 20 lists the header &lt;memory&gt; (only) for
Memory (lib.memory) but neglects to mention the headers
&lt;cstdlib&gt; and &lt;cstring&gt; that are discussed in 20.4.6 <a href="lib-utilities.html#lib.c.malloc"> [lib.c.malloc]</a>.</p>
<p><b>Proposed resolution:</b></p>
<p>Add &lt;cstdlib&gt; and &lt;cstring&gt; to Table 27, in the same row
as &lt;memory&gt;.</p>
<hr>
<a name="315"><h3>315.&nbsp;Bad "range" in list::unique complexity</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#WP">WP</a>&nbsp; <b>Submitter:</b>&nbsp;Andy Sawyer&nbsp; <b>Date:</b>&nbsp;1 May 2001</p>
<p>
23.2.2.4 <a href="lib-containers.html#lib.list.ops"> [lib.list.ops]</a>, Para 21 describes the complexity of
list::unique as: "If the range (last - first) is not empty, exactly
(last - first) -1 applications of the corresponding predicate,
otherwise no applications of the predicate)".
</p>

<p>
"(last - first)" is not a range.
</p>
<p><b>Proposed resolution:</b></p>
<p>
Change the "range" from (last - first) to [first, last).
</p>
<hr>
<a name="316"><h3>316.&nbsp;Vague text in Table 69</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#WP">WP</a>&nbsp; <b>Submitter:</b>&nbsp;Martin Sebor&nbsp; <b>Date:</b>&nbsp;4 May 2001</p>
<p>Table 69 says this about a_uniq.insert(t):</p>

<blockquote>
inserts t if and only if there is no element in the container with key
equivalent to the key of t. The bool component of the returned pair 
indicates whether the insertion takes place and the iterator component of the
pair points to the element with key equivalent to the key of t.
</blockquote>

<p>The description should be more specific about exactly how the bool component
indicates whether the insertion takes place.</p>
<p><b>Proposed resolution:</b></p>
<p>Change the text in question to</p>

<blockquote>
...The bool component of the returned pair is true if and only if the insertion
takes place...
</blockquote>
<hr>
<a name="317"><h3>317.&nbsp;Instantiation vs. specialization of facets</h3></a><p><b>Section:</b>&nbsp;22 <a href="lib-locales.html#lib.localization"> [lib.localization]</a>&nbsp; <b>Status:</b>&nbsp;<a href="lwg-active.html#WP">WP</a>&nbsp; <b>Submitter:</b>&nbsp;Martin Sebor&nbsp; <b>Date:</b>&nbsp;4 May 2001</p>
<p>
The localization section of the standard refers to specializations of
the facet templates as instantiations even though the required facets
are typically specialized rather than explicitly (or implicitly)
instantiated. In the case of ctype&lt;char&gt; and
ctype_byname&lt;char&gt; (and the wchar_t versions), these facets are
actually required to be specialized. The terminology should be
corrected to make it clear that the standard doesn't mandate explicit
instantiation (the term specialization encompasses both explicit
instantiations and specializations).
</p>
<p><b>Proposed resolution:</b></p>
<p>
In the following paragraphs, replace all occurrences of the word
instantiation or instantiations with specialization or specializations,
respectively:
</p>

<blockquote>
22.1.1.1.1, p4, Table 52, 22.2.1.1, p2, 22.2.1.5, p3, 22.2.1.5.1, p5,
22.2.1.5.2, p10, 22.2.2, p2, 22.2.3.1, p1, 22.2.3.1.2, p1, p2 and p3, 
22.2.4.1, p1, 22.2.4.1.2, p1, 22,2,5, p1, 22,2,6, p2, 22.2.6.3.2, p7, and
Footnote 242.
</blockquote>

<p>And change the text in 22.1.1.1.1, p4 from</p>

<blockquote>
    An implementation is required to provide those instantiations
    for facet templates identified as members of a category, and
    for those shown in Table 52:
</blockquote>

<p>to</p>

<blockquote>
    An implementation is required to provide those specializations...
</blockquote>

<p><i>[Nathan will review these changes, and will look for places where
explicit specialization is necessary.]</i></p>

<p><b>Rationale:</b></p>
<p>This is a simple matter of outdated language.  The language to
describe templates was clarified during the standardization process,
but the wording in clause 22 was never updated to reflect that
change.</p>
<hr>
<a name="318"><h3>318.&nbsp;Misleading comment in definition of numpunct_byname</h3></a><p><b>Section:</b>&nbsp;22.2.3.2 <a href="lib-locales.html#lib.locale.numpunct.byname"> [lib.locale.numpunct.byname]</a>&nbsp; <b>Status:</b>&nbsp;<a href="lwg-active.html#WP">WP</a>&nbsp; <b>Submitter:</b>&nbsp;Martin Sebor&nbsp; <b>Date:</b>&nbsp;12 May 2001</p>
<p>The definition of the numpunct_byname template contains the following
comment:</p>

<pre>
    namespace std {
        template &lt;class charT&gt;
        class numpunct_byname : public numpunct&lt;charT&gt; {
    // this class is specialized for char and wchar_t.
        ...
</pre>

<p>There is no documentation of the specializations and it seems
conceivable that an implementation will not explicitly specialize the
template at all, but simply provide the primary template.</p>
<p><b>Proposed resolution:</b></p>
<p>Remove the comment from the text in 22.2.3.2 and from the proposed
resolution of library issue <a href="lwg-defects.html#228">228</a>.</p>
<hr>
<a name="319"><h3>319.&nbsp;Storage allocation wording confuses "Required behavior", "Requires"</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>, 18.4.1.2 <a href="lib-support.html#lib.new.delete.array"> [lib.new.delete.array]</a>&nbsp; <b>Status:</b>&nbsp;<a href="lwg-active.html#WP">WP</a>&nbsp; <b>Submitter:</b>&nbsp;Beman Dawes&nbsp; <b>Date:</b>&nbsp;15 May 2001</p>
<p>The standard specifies 17.3.1.3 <a href="lib-intro.html#lib.structure.specifications"> [lib.structure.specifications]</a> that "Required
behavior" elements describe "the semantics of a function definition
provided by either the implementation or a C++ program."</p>

<p>The standard specifies 17.3.1.3 <a href="lib-intro.html#lib.structure.specifications"> [lib.structure.specifications]</a> that "Requires"
elements describe "the preconditions for calling the function."</p>

<p>In the sections noted below, the current wording specifies
"Required Behavior" for what are actually preconditions, and thus
should be specified as "Requires".</p>

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

<p>In 18.4.1.1 <a href="lib-support.html#lib.new.delete.single"> [lib.new.delete.single]</a> Para 12 Change:</p>
<blockquote>
  <p>Required behavior: accept a value of ptr that is null or that was
  returned by an earlier call ...</p>
</blockquote>
<p>to:</p>
<blockquote>
  <p>Requires: the value of ptr is null or the value returned by an
  earlier call ...</p>
</blockquote>

<p>In 18.4.1.2 <a href="lib-support.html#lib.new.delete.array"> [lib.new.delete.array]</a> Para 11 Change:</p>
<blockquote>
  <p>Required behavior: accept a value of ptr that is null or that was
  returned by an earlier call ...</p>
</blockquote>
<p>to:</p>
<blockquote>
  <p>Requires: the value of ptr is null or the value returned by an
  earlier call ...</p>
</blockquote>

<hr>
<a name="320"><h3>320.&nbsp;list::assign overspecified</h3></a><p><b>Section:</b>&nbsp;23.2.2.1 <a href="lib-containers.html#lib.list.cons"> [lib.list.cons]</a>&nbsp; <b>Status:</b>&nbsp;<a href="lwg-active.html#WP">WP</a>&nbsp; <b>Submitter:</b>&nbsp;Howard Hinnant&nbsp; <b>Date:</b>&nbsp;17 May 2001</p>
<p>
Section 23.2.2.1, paragraphs 6-8 specify that list assign (both forms) have
the "effects" of a call to erase followed by a call to insert.
</p>

<p>
I would like to document that implementers have the freedom to implement 
assign by other methods, as long as the end result is the same and the 
exception guarantee is as good or better than the basic guarantee.
</p>

<p>
The motivation for this is to use T's assignment operator to recycle
existing nodes in the list instead of erasing them and reallocating
them with new values.  It is also worth noting that, with careful
coding, most common cases of assign (everything but assignment with
true input iterators) can elevate the exception safety to strong if
T's assignment has a nothrow guarantee (with no extra memory cost).
Metrowerks does this.  However I do not propose that this subtlety be
standardized.  It is a QoI issue.  </p>

<p>Existing practise:
Metrowerks and SGI recycle nodes, Dinkumware and Rogue Wave don't.
</p>
<p><b>Proposed resolution:</b></p>
<p>Change 23.2.2.1/7 from:</p>

<blockquote>
<p>Effects:</p>

<pre>
   erase(begin(), end());
   insert(begin(), first, last);
</pre>
</blockquote>

<p>to:</p>

<blockquote>
<p>Effects: Replaces the contents of the list with the range [first, last).</p>
</blockquote>

<p>In 23.1.1 <a href="lib-containers.html#lib.sequence.reqmts"> [lib.sequence.reqmts]</a>, in Table 67 (sequence requirements), 
add two new rows:</p>
<pre>
      a.assign(i,j)     void      pre: i,j are not iterators into a.
                                  Replaces elements in a with a copy
                                  of [i, j).

      a.assign(n,t)     void      pre: t is not a reference into a.
                                  Replaces elements in a with n copies
                                  of t.
</pre>

<p>Change 23.2.2.1/8 from:</p>

<blockquote>
<p>Effects:</p>
<pre>
   erase(begin(), end());
   insert(begin(), n, t);
</pre>
</blockquote>
<p>to:</p>

<blockquote>
<p>Effects: Replaces the contents of the list with n copies of t.</p>
</blockquote>

<p><i>[Redmond: Proposed resolution was changed slightly.  Previous
version made explicit statement about exception safety, which wasn't
consistent with the way exception safety is expressed elsewhere.
Also, the change in the sequence requirements is new.  Without that
change, the proposed resolution would have required that assignment of
a subrange would have to work.  That too would have been
overspecification; it would effectively mandate that assignment use a
temporary.  Howard provided wording.
]</i></p>

<p><i>[Cura&ccedil;ao: Made editorial improvement in wording; changed
"Replaces elements in a with copies of elements in [i, j)."
with "Replaces the elements of a with a copy of [i, j)."
Changes not deemed serious enough to requre rereview.]</i></p>

<hr>
<a name="321"><h3>321.&nbsp;Typo in num_get</h3></a><p><b>Section:</b>&nbsp;22.2.2.1.2 <a href="lib-locales.html#lib.facet.num.get.virtuals"> [lib.facet.num.get.virtuals]</a>&nbsp; <b>Status:</b>&nbsp;<a href="lwg-active.html#WP">WP</a>&nbsp; <b>Submitter:</b>&nbsp;Kevin Djang&nbsp; <b>Date:</b>&nbsp;17 May 2001</p>
<p>
Section 22.2.2.1.2 at p7 states that "A length specifier is added to
the conversion function, if needed, as indicated in Table 56."
However, Table 56 uses the term "length modifier", not "length
specifier".
</p>
<p><b>Proposed resolution:</b></p>
<p>
In 22.2.2.1.2 at p7, change the text "A length specifier is added ..."
to be "A length modifier is added ..."
</p>
<p><b>Rationale:</b></p>
<p>C uses the term "length modifier".  We should be consistent.</p>
<hr>
<a name="322"><h3>322.&nbsp;iterator and const_iterator should have the same value type</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#WP">WP</a>&nbsp; <b>Submitter:</b>&nbsp;Matt Austern&nbsp; <b>Date:</b>&nbsp;17 May 2001</p>
<p>
It's widely assumed that, if X is a container,
iterator_traits&lt;X::iterator&gt;::value_type and
iterator_traits&lt;X::const_iterator&gt;::value_type should both be
X::value_type.  However, this is nowhere stated.  The language in
Table 65 is not precise about the iterators' value types (it predates
iterator_traits), and could even be interpreted as saying that
iterator_traits&lt;X::const_iterator&gt;::value_type should be "const
X::value_type".
</p>

<p>Related issue: <a href="lwg-closed.html#279">279</a>.</p>
<p><b>Proposed resolution:</b></p>
<p>In Table 65 ("Container Requirements"), change the return type for
X::iterator to "iterator type whose value type is T".  Change the
return type for X::const_iterator to "constant iterator type whose
value type is T".</p>
<p><b>Rationale:</b></p>
<p>
This belongs as a container requirement, rather than an iterator
requirement, because the whole notion of iterator/const_iterator
pairs is specific to containers' iterator.
</p>
<p>
It is existing practice that (for example) 
iterator_traits&lt;list&lt;int&gt;::const_iterator&gt;::value_type
is "int", rather than "const int".  This is consistent with
the way that const pointers are handled: the standard already 
requires that iterator_traits&lt;const int*&gt;::value_type is int.
</p>
<hr>
<a name="324"><h3>324.&nbsp;Do output iterators have value types?</h3></a><p><b>Section:</b>&nbsp;24.1.2 <a href="lib-iterators.html#lib.output.iterators"> [lib.output.iterators]</a>&nbsp; <b>Status:</b>&nbsp;<a href="lwg-active.html#WP">WP</a>&nbsp; <b>Submitter:</b>&nbsp;Dave Abrahams&nbsp; <b>Date:</b>&nbsp;7 June 2001</p>

<p>Table 73 suggests that output iterators have value types.  It 
requires the expression "*a = t".  Additionally, although Table 73
never lists "a = t" or "X(a) = t" in the "expressions" column, it
contains a note saying that "a = t" and "X(a) = t" have equivalent
(but nowhere specified!) semantics.</p>

<p>According to 24.1/9, t is supposed to be "a value of value type
T":</p>

    <blockquote>
    In the following sections, a and b denote values of X, n denotes a
    value of the difference type Distance, u, tmp, and m denote
    identifiers, r denotes a value of X&amp;, t denotes a value of
    value type T.
    </blockquote>

<p>Two other parts of the standard that are relevant to whether
output iterators have value types:</p>

<ul>
    <li>24.1/1 says "All iterators i support the expression *i,
    resulting in a value of some class, enumeration, or built-in type
    T, called the value type of the iterator".</li>

    <li>
    24.3.1/1, which says "In the case of an output iterator, the types
    iterator_traits&lt;Iterator&gt;::difference_type
    iterator_traits&lt;Iterator&gt;::value_type are both defined as void."
    </li>
</ul>

<p>The first of these passages suggests that "*i" is supposed to
return a useful value, which contradicts the note in 24.1.2/2 saying
that the only valid use of "*i" for output iterators is in an
expression of the form "*i = t".  The second of these passages appears
to contradict Table 73, because it suggests that "*i"'s return value
should be void.  The second passage is also broken in the case of a an
iterator type, like non-const pointers, that satisfies both the output
iterator requirements and the forward iterator requirements.</p>

<p>What should the standard say about <tt>*i</tt>'s return value when
i is an output iterator, and what should it say about that t is in the
expression "*i = t"?  Finally, should the standard say anything about
output iterators' pointer and reference types?</p>

<p><b>Proposed resolution:</b></p>
<p>24.1 p1, change</p>

<blockquote>
<p>All iterators <tt>i</tt> support the expression <tt>*i</tt>, resulting
in a value of some class, enumeration, or built-in type <tt>T</tt>,
called the value type of the iterator.</p>
</blockquote>

<p>to</p>

<blockquote>
<p>All input iterators <tt>i</tt> support the expression <tt>*i</tt>,
resulting in a value of some class, enumeration, or built-in type
<tt>T</tt>, called the value type of the iterator. All output
iterators support the expression <tt>*i = o</tt> where <tt>o</tt> is a
value of some type that is in the set of types that are <i>writable</i> to
the particular iterator type of <tt>i</tt>.
</p>
</blockquote>

<p>24.1 p9, add</p>

<blockquote>
<p><tt>o</tt> denotes a value of some type that is writable to the
output iterator.
</p>
</blockquote>

<p>Table 73, change</p>

<blockquote>
<pre>
*a = t
</pre>
</blockquote>

<p>to</p>

<blockquote>
<pre>
*r = o
</pre>
</blockquote>

<p>and change</p>

<blockquote>
<pre>
*r++ = t
</pre>
</blockquote>

<p>to</p>

<blockquote>
<pre>
*r++ = o
</pre>
</blockquote>

<p><i>[post-Redmond: Jeremy provided wording]</i></p>

<p><b>Rationale:</b></p>
<p>The LWG considered two options: change all of the language that
seems to imply that output iterators have value types, thus making it
clear that output iterators have no value types, or else define value
types for output iterator consistently.  The LWG chose the former
option, because it seems clear that output iterators were never
intended to have value types.  This was a deliberate design decision,
and any language suggesting otherwise is simply a mistake.</p>

<p>A future revision of the standard may wish to revisit this design
decision.</p>
<hr>
<a name="325"><h3>325.&nbsp;Misleading text in moneypunct&lt;&gt;::do_grouping</h3></a><p><b>Section:</b>&nbsp;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#WP">WP</a>&nbsp; <b>Submitter:</b>&nbsp;Martin Sebor&nbsp; <b>Date:</b>&nbsp;02 Jul 2001</p>
<p>The Returns clause in 22.2.6.3.2, p3 says about
moneypunct&lt;charT&gt;::do_grouping()
</p>

<blockquote>
    Returns: A pattern defined identically as the result of
    numpunct&lt;charT&gt;::do_grouping().241)
</blockquote>

<p>Footnote 241 then reads</p>

<blockquote>
    This is most commonly the value "\003" (not "3").
</blockquote>

<p>
The returns clause seems to imply that the two member functions must
return an identical value which in reality may or may not be true,
since the facets are usually implemented in terms of struct std::lconv
and return the value of the grouping and mon_grouping, respectively.
The footnote also implies that the member function of the moneypunct
facet (rather than the overridden virtual functions in moneypunct_byname)
most commonly return "\003", which contradicts the C standard which
specifies the value of "" for the (most common) C locale.
</p>

<p><b>Proposed resolution:</b></p>
<p>Replace the text in Returns clause in 22.2.6.3.2, p3 with the following:</p>

<blockquote>
    Returns: A pattern defined identically as, but not necessarily
    equal to, the result of numpunct&lt;charT&gt;::do_grouping().241)
</blockquote>

<p>and replace the text in Footnote 241 with the following:</p>

<blockquote>
    To specify grouping by 3s the value is "\003", not "3".
</blockquote>
<p><b>Rationale:</b></p>
<p>
The fundamental problem is that the description of the locale facet
virtuals serves two purposes: describing the behavior of the base
class, and describing the meaning of and constraints on the behavior
in arbitrary derived classes.  The new wording makes that separation a
little bit clearer.  The footnote (which is nonnormative) is not
supposed to say what the grouping is in the "C" locale or in any other
locale. It is just a reminder that the values are interpreted as small
integers, not ASCII characters.
</p>
<hr>
<a name="327"><h3>327.&nbsp;Typo in time_get facet in table 52</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#WP">WP</a>&nbsp; <b>Submitter:</b>&nbsp;Tiki Wan&nbsp; <b>Date:</b>&nbsp;06 Jul 2001</p>
<p>The <tt>wchar_t</tt> versions of <tt>time_get</tt> and
<tt>time_get_byname</tt> are listed incorrectly in table 52,
required instantiations.  In both cases the second template
parameter is given as OutputIterator.  It should instead be
InputIterator, since these are input facets.</p>
<p><b>Proposed resolution:</b></p>
<p>
In table 52, required instantiations, in 
22.1.1.1.1 <a href="lib-locales.html#lib.locale.category"> [lib.locale.category]</a>, change</p>
<pre>
    time_get&lt;wchar_t, OutputIterator&gt;
    time_get_byname&lt;wchar_t, OutputIterator&gt;
</pre>
<p>to</p>
<pre>
    time_get&lt;wchar_t, InputIterator&gt;
    time_get_byname&lt;wchar_t, InputIterator&gt;
</pre>

<p><i>[Redmond: Very minor change in proposed resolution.  Original had
a typo, wchart instead of wchar_t.]</i></p>

<hr>
<a name="328"><h3>328.&nbsp;Bad sprintf format modifier in money_put&lt;&gt;::do_put()</h3></a><p><b>Section:</b>&nbsp;22.2.6.2.2 <a href="lib-locales.html#lib.locale.money.put.virtuals"> [lib.locale.money.put.virtuals]</a>&nbsp; <b>Status:</b>&nbsp;<a href="lwg-active.html#WP">WP</a>&nbsp; <b>Submitter:</b>&nbsp;Martin Sebor&nbsp; <b>Date:</b>&nbsp;07 Jul 2001</p>
<p>The sprintf format string , "%.01f" (that's the digit one), in the
description of the do_put() member functions of the money_put facet in
22.2.6.2.2, p1 is incorrect. First, the f format specifier is wrong
for values of type long double, and second, the precision of 01
doesn't seem to make sense. What was most likely intended was
"%.0Lf"., that is a precision of zero followed by the L length
modifier.</p>
<p><b>Proposed resolution:</b></p>
<p>Change the format string to "%.0Lf".</p>
<p><b>Rationale:</b></p>
<p>Fixes an obvious typo</p>
<hr>
<a name="329"><h3>329.&nbsp;vector capacity, reserve and reallocation</h3></a><p><b>Section:</b>&nbsp;23.2.4.2 <a href="lib-containers.html#lib.vector.capacity"> [lib.vector.capacity]</a>, 23.2.4.3 <a href="lib-containers.html#lib.vector.modifiers"> [lib.vector.modifiers]</a>&nbsp; <b>Status:</b>&nbsp;<a href="lwg-active.html#WP">WP</a>&nbsp; <b>Submitter:</b>&nbsp;Anthony Williams&nbsp; <b>Date:</b>&nbsp;13 Jul 2001</p>
<p>
There is an apparent contradiction about which circumstances can cause
a reallocation of a vector in Section 23.2.4.2 <a href="lib-containers.html#lib.vector.capacity"> [lib.vector.capacity]</a> and
section 23.2.4.3 <a href="lib-containers.html#lib.vector.modifiers"> [lib.vector.modifiers]</a>.
</p>

<p>23.2.4.2p5 says:</p>
<blockquote>
Notes: Reallocation invalidates all the references, pointers, and iterators
referring to the elements in the sequence. It is guaranteed that no
reallocation takes place during insertions that happen after a call to
reserve() until the time when an insertion would make the size of the vector
greater than the size specified in the most recent call to reserve().
</blockquote>

<p>Which implies if I do</p>

<pre>
  std::vector&lt;int&gt; vec;
  vec.reserve(23);
  vec.reserve(0);
  vec.insert(vec.end(),1);
</pre>

<p>then the implementation may reallocate the vector for the insert,
as the size specified in the previous call to reserve was zero.</p>

<p>However, the previous paragraphs (23.2.4.2, p1-2) state:</p>
<blockquote>
<p>
(capacity) Returns: The total number of elements the vector
can hold without requiring reallocation
</p>
<p>
...After reserve(), capacity() is greater or equal to the
argument of reserve if reallocation happens; and equal to the previous value
of capacity() otherwise...
</p>
</blockquote>

<p>
This implies that vec.capacity() is still 23, and so the insert()
should not require a reallocation, as vec.size() is 0. This is backed
up by 23.2.4.3p1:
</p>
<blockquote>
(insert) Notes: Causes reallocation if the new size is greater than the old
capacity.
</blockquote>

<p>
Though this doesn't rule out reallocation if the new size is less
than the old capacity, I think the intent is clear.
</p>

<p><b>Proposed resolution:</b></p>
<p>Change the wording of 23.2.4.2 <a href="lib-containers.html#lib.vector.capacity"> [lib.vector.capacity]</a> paragraph 5 to:</p>

<blockquote>
Notes: Reallocation invalidates all the references, pointers, and
iterators referring to the elements in the sequence. It is guaranteed
that no reallocation takes place during insertions that happen after a
call to reserve() until the time when an insertion would make the size
of the vector greater than the value of capacity().
</blockquote>

<p><i>[Redmond: original proposed resolution was modified slightly.  In
the original, the guarantee was that there would be no reallocation
until the size would be greater than the value of capacity() after the
most recent call to reserve().  The LWG did not believe that the
"after the most recent call to reserve()" added any useful
information.]</i></p>

<p><b>Rationale:</b></p>
<p>There was general agreement that, when reserve() is called twice in
succession and the argument to the second invocation is smaller than
the argument to the first, the intent was for the second invocation to
have no effect.  Wording implying that such cases have an effect on
reallocation guarantees was inadvertant.</p>
<hr>
<a name="331"><h3>331.&nbsp;bad declaration of destructor for ios_base::failure</h3></a><p><b>Section:</b>&nbsp;27.4.2.1.1 <a href="lib-iostreams.html#lib.ios::failure"> [lib.ios::failure]</a>&nbsp; <b>Status:</b>&nbsp;<a href="lwg-active.html#WP">WP</a>&nbsp; <b>Submitter:</b>&nbsp;PremAnand M. Rao&nbsp; <b>Date:</b>&nbsp;23 Aug 2001</p>
<p>
With the change in 17.4.4.8 <a href="lib-intro.html#lib.res.on.exception.handling"> [lib.res.on.exception.handling]</a> to state
   "An implementation may strengthen the exception-specification for a 
    non-virtual function by removing listed exceptions."
(issue <a href="lwg-defects.html#119">119</a>)
and the following declaration of ~failure() in ios_base::failure
</p>
<pre>
    namespace std {
       class ios_base::failure : public exception {
       public:
           ...
           virtual ~failure();
           ...
       };
     }
</pre>
<p>the class failure cannot be implemented since in 18.6.1 <a href="lib-support.html#lib.exception"> [lib.exception]</a> the destructor of class exception has an empty
exception specification:</p>
<pre>
    namespace std {
       class exception {
       public:
         ...
         virtual ~exception() throw();
         ...
       };
     }
</pre>
<p><b>Proposed resolution:</b></p>
<p>Remove the declaration of ~failure().</p>
<p><b>Rationale:</b></p>
<p>The proposed resolution is consistent with the way that destructors
of other classes derived from <tt>exception</tt> are handled.</p>
<hr>
<a name="333"><h3>333.&nbsp;does endl imply synchronization with the device?</h3></a><p><b>Section:</b>&nbsp;27.6.2.7 <a href="lib-iostreams.html#lib.ostream.manip"> [lib.ostream.manip]</a>&nbsp; <b>Status:</b>&nbsp;<a href="lwg-active.html#WP">WP</a>&nbsp; <b>Submitter:</b>&nbsp;PremAnand M. Rao&nbsp; <b>Date:</b>&nbsp;27 Aug 2001</p>
<p>A footnote in 27.6.2.7 <a href="lib-iostreams.html#lib.ostream.manip"> [lib.ostream.manip]</a> states:</p>
<blockquote>
    [Footnote: The effect of executing cout &lt;&lt; endl is to insert a 
     newline character in the output sequence controlled by cout, then 
     synchronize it with any external file with which it might be 
     associated. --- end foonote]
</blockquote>

<p>
Does the term "file" here refer to the external device?
This leads to some implementation ambiguity on systems with fully 
buffered files where a newline does not cause a flush to the device.
</p>

<p>
Choosing to sync with the device leads to significant performance
penalties for each call to endl, while not sync-ing leads to
errors under special circumstances.
</p>

<p>
I could not find any other statement that explicitly defined
the behavior one way or the other.
</p>
<p><b>Proposed resolution:</b></p>
<p>Remove footnote 300 from section 27.6.2.7 <a href="lib-iostreams.html#lib.ostream.manip"> [lib.ostream.manip]</a>.</p>
<p><b>Rationale:</b></p>
<p>We already have normative text saying what <tt>endl</tt> does: it
inserts a newline character and calls <tt>flush</tt>.  This footnote
is at best redundant, at worst (as this issue says) misleading,
because it appears to make promises about what <tt>flush</tt>
does.</p>
<hr>
<a name="334"><h3>334.&nbsp;map::operator[] specification forces inefficient implementation</h3></a><p><b>Section:</b>&nbsp;23.3.1.2 <a href="lib-containers.html#lib.map.access"> [lib.map.access]</a>&nbsp; <b>Status:</b>&nbsp;<a href="lwg-active.html#WP">WP</a>&nbsp; <b>Submitter:</b>&nbsp;Andrea Griffini&nbsp; <b>Date:</b>&nbsp;02 Sep 2001</p>
<p>
The current standard describes map::operator[] using a
code example. That code example is however quite
inefficient because it requires several useless copies
of both the passed key_type value and of default
constructed mapped_type instances.
My opinion is that was not meant by the comitee to
require all those temporary copies. 
</p>

<p>Currently map::operator[] behaviour is specified as: </p>
<pre>
  Returns:
    (*((insert(make_pair(x, T()))).first)).second.
</pre>
  
<p>
This specification however uses make_pair that is a
template function of which parameters in this case
will be deduced being of type const key_type&amp; and
const T&amp;. This will create a pair&lt;key_type,T&gt; that
isn't the correct type expected by map::insert so
another copy will be required using the template
conversion constructor available in pair to build
the required pair&lt;const key_type,T&gt; instance.
</p>

<p>If we consider calling of key_type copy constructor
and mapped_type default constructor and copy
constructor as observable behaviour (as I think we
should) then the standard is in this place requiring
two copies of a key_type element plus a default
construction and two copy construction of a mapped_type
(supposing the addressed element is already present
in the map; otherwise at least another copy
construction for each type). 
</p>

<p>A simple (half) solution would be replacing the description with:</p>
<pre>
  Returns:
    (*((insert(value_type(x, T()))).first)).second.
</pre>

<p>This will remove the wrong typed pair construction that
requires one extra copy of both key and value.</p>

<p>However still the using of map::insert requires temporary
objects while the operation, from a logical point of view,
doesn't require any. </p>

<p>I think that a better solution would be leaving free an
implementer to use a different approach than map::insert
that, because of its interface, forces default constructed
temporaries and copies in this case.
The best solution in my opinion would be just requiring
map::operator[] to return a reference to the mapped_type
part of the contained element creating a default element
with the specified key if no such an element is already
present in the container. Also a logarithmic complexity
requirement should be specified for the operation.
</p>

<p>
This would allow library implementers to write alternative
implementations not using map::insert and reaching optimal
performance in both cases of the addressed element being
present or absent from the map (no temporaries at all and
just the creation of a new pair inside the container if
the element isn't present).
Some implementer has already taken this option but I think
that the current wording of the standard rules that as
non-conforming. 
</p>

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

<p>
Replace 23.3.1.2 <a href="lib-containers.html#lib.map.access"> [lib.map.access]</a> paragraph 1 with
</p>
<blockquote>
<p>
-1- Effects:  If there is no key equivalent to x in the map, inserts 
value_type(x, T()) into the map.
</p>
<p>
-2- Returns: A reference to the mapped_type corresponding to x in *this.
</p>
<p>
-3- Complexity: logarithmic.
</p>
</blockquote>

<p><i>[This is the second option mentioned above.  Howard provided
wording.  We may also wish to have a blanket statement somewhere in
clause 17 saying that we do not intend the semantics of sample code
fragments to be interpreted as specifing exactly how many copies are
made.  See issue <a href="lwg-defects.html#98">98</a> for a similar problem.]</i></p>

<p><b>Rationale:</b></p>
<p>
This is the second solution described above; as noted, it is
consistent with existing practice.
</p>

<p>Note that we now need to specify the complexity explicitly, because
we are no longer defining <tt>operator[]</tt> in terms of
<tt>insert</tt>.</p>
<hr>
<a name="335"><h3>335.&nbsp;minor issue with char_traits, table 37</h3></a><p><b>Section:</b>&nbsp;21.1.1 <a href="lib-strings.html#lib.char.traits.require"> [lib.char.traits.require]</a>&nbsp; <b>Status:</b>&nbsp;<a href="lwg-active.html#WP">WP</a>&nbsp; <b>Submitter:</b>&nbsp;Andy Sawyer&nbsp; <b>Date:</b>&nbsp;06 Sep 2001</p>
<p>
Table 37, in 21.1.1 <a href="lib-strings.html#lib.char.traits.require"> [lib.char.traits.require]</a>, descibes char_traits::assign
as:
</p>
<pre>
  X::assign(c,d)   assigns c = d.
</pre>

<p>And para 1 says:</p>

<blockquote>
 [...] c and d denote values of type CharT [...]
</blockquote>

<p>
Naturally, if c and d are <i>values</i>, then the assignment is
(effectively) meaningless. It's clearly intended that (in the case of
assign, at least), 'c' is intended to be a reference type.
</p>

<p>I did a quick survey of the four implementations I happened to have
lying around, and sure enough they all have signatures:</p>
<pre>
    assign( charT&amp;, const charT&amp; );
</pre>

<p>(or the equivalent). It's also described this way in Nico's book.
(Not to mention the synopses of char_traits&lt;char&gt; in 21.1.3.1
and char_traits&lt;wchar_t&gt; in 21.1.3.2...)
</p>
<p><b>Proposed resolution:</b></p>
<p>Add the following to 21.1.1 para 1:</p>
<blockquote>
 r denotes an lvalue of CharT
</blockquote>

<p>and change the description of assign in the table to:</p>
<pre>
  X::assign(r,d)   assigns r = d
</pre>
<hr>
<a name="336"><h3>336.&nbsp;Clause 17 lack of references to deprecated headers</h3></a><p><b>Section:</b>&nbsp;17 <a href="lib-intro.html#lib.library"> [lib.library]</a>&nbsp; <b>Status:</b>&nbsp;<a href="lwg-active.html#WP">WP</a>&nbsp; <b>Submitter:</b>&nbsp;Detlef Vollmann&nbsp; <b>Date:</b>&nbsp;05 Sep 2001</p>
<p>From c++std-edit-873:</p>

<p>17.4.1.2 <a href="lib-intro.html#lib.headers"> [lib.headers]</a>, Table 11.  In this table, the header
&lt;strstream&gt; is missing.</p>

<p>This shows a general problem: The whole clause 17 refers quite
often to clauses 18 through 27, but D.7 is also a part of the standard
library (though a deprecated one).</p>

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

<p>To 17.4.1.2 <a href="lib-intro.html#lib.headers"> [lib.headers]</a> Table 11, C++ Library Headers, add
"&lt;strstream&gt;".</p>

<p>In the following places, change "clauses 17 through 27" to "clauses
17 through 27 and Annex D":</p>

<ul>
<li>1.2 <a href="intro.html#intro.refs"> [intro.refs]</a> Normative references/1/footnote 1</li>
<li>1.3 <a href="intro.html#intro.defs"> [intro.defs]</a> Definitions/1</li>
<li>7 <a href="dcl.html#dcl.dcl"> [dcl.dcl]</a> Library introduction/9</li>
<li>17.3 <a href="lib-intro.html#lib.description"> [lib.description]</a> Method of description (Informative)/1</li>
<li>17.3.2.1.3 <a href="lib-intro.html#lib.character.seq"> [lib.character.seq]</a> Character sequences/1/bullet 2</li>
<li>17.3.2.2 <a href="lib-intro.html#lib.functions.within.classes"> [lib.functions.within.classes]</a> Functions within classes/1</li>
<li>17.3.2.3 <a href="lib-intro.html#lib.objects.within.classes"> [lib.objects.within.classes]</a> Private members/1/(2 places)</li>
<li>17.4 <a href="lib-intro.html#lib.requirements"> [lib.requirements]</a> Library-wide requirements/1</li>
<li>17.4.1.2 <a href="lib-intro.html#lib.headers"> [lib.headers]</a> Headers/4</li>
<li>17.4.3.4 <a href="lib-intro.html#lib.replacement.functions"> [lib.replacement.functions]</a> Replacement functions/1</li>
<li>17.4.4.3 <a href="lib-intro.html#lib.global.functions"> [lib.global.functions]</a> Global or non-member functions/2</li>
<li>17.4.4.6 <a href="lib-intro.html#lib.protection.within.classes"> [lib.protection.within.classes]</a> Protection within classes/1</li>
</ul>


<hr>
<a name="337"><h3>337.&nbsp;replace_copy_if's template parameter should be InputIterator</h3></a><p><b>Section:</b>&nbsp;25.2.4 <a href="lib-algorithms.html#lib.alg.replace"> [lib.alg.replace]</a>&nbsp; <b>Status:</b>&nbsp;<a href="lwg-active.html#WP">WP</a>&nbsp; <b>Submitter:</b>&nbsp;Detlef Vollmann&nbsp; <b>Date:</b>&nbsp;07 Sep 2001</p>
<p>From c++std-edit-876:</p>

<p>
In section 25.2.4 <a href="lib-algorithms.html#lib.alg.replace"> [lib.alg.replace]</a> before p4: The name of the first
parameter of template replace_copy_if should be "InputIterator"
instead of "Iterator".  According to 17.3.2.1 <a href="lib-intro.html#lib.type.descriptions"> [lib.type.descriptions]</a> p1 the
parameter name conveys real normative meaning.
</p>
<p><b>Proposed resolution:</b></p>
<p>Change <tt>Iterator</tt> to <tt>InputIterator</tt>.</p>
<hr>
<a name="338"><h3>338.&nbsp; is whitespace allowed between `-' and a digit?</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#WP">WP</a>&nbsp; <b>Submitter:</b>&nbsp;Martin Sebor&nbsp; <b>Date:</b>&nbsp;17 Sep 2001</p>
<p>
From Stage 2 processing in 22.2.2.1.2 <a href="lib-locales.html#lib.facet.num.get.virtuals"> [lib.facet.num.get.virtuals]</a>, p8 and 9 (the
original text or the text corrected by the proposed resolution of
issue <a href="lwg-defects.html#221">221</a>) it seems clear that no whitespace is allowed
within a number, but 22.2.3.1 <a href="lib-locales.html#lib.locale.numpunct"> [lib.locale.numpunct]</a>, p2, which gives the
format for integer and floating point values, says that whitespace is
optional between a plusminus and a sign.
</p>

<p>
The text needs to be clarified to either consistently allow or
disallow whitespace between a plusminus and a sign. It might be
worthwhile to consider the fact that the C library stdio facility does
not permit whitespace embedded in numbers and neither does the C or
C++ core language (the syntax of integer-literals is given in 2.13.1 <a href="lex.html#lex.icon"> [lex.icon]</a>, that of floating-point-literals in 2.13.3 <a href="lex.html#lex.fcon"> [lex.fcon]</a> of the C++ standard).
</p>
<p><b>Proposed resolution:</b></p>
<p>Change the first part of 22.2.3.1 <a href="lib-locales.html#lib.locale.numpunct"> [lib.locale.numpunct]</a> paragraph 2 from:</p>
<blockquote>
<p>
The syntax for number formats is as follows, where <tt>digit</tt>
represents the radix set specified by the <tt>fmtflags</tt> argument
value, <tt>whitespace</tt> is as determined by the facet
<tt>ctype&lt;charT&gt;</tt> (22.2.1.1), and <tt>thousands-sep</tt> and
<tt>decimal-point</tt> are the results of corresponding
<tt>numpunct&lt;charT&gt;</tt> members.  Integer values have the
format:
</p>
<pre>
  integer   ::= [sign] units
  sign      ::= plusminus [whitespace]
  plusminus ::= '+' | '-'
  units     ::= digits [thousands-sep units]
  digits    ::= digit [digits]
</pre>
</blockquote>
<p>to:</p>
<blockquote>
<p>
The syntax for number formats is as follows, where <tt>digit</tt>
represents the radix set specified by the <tt>fmtflags</tt> argument
value, and <tt>thousands-sep</tt> and <tt>decimal-point</tt> are the
results of corresponding <tt>numpunct&lt;charT&gt;</tt> members.
Integer values have the format:
</p>
<pre>
  integer   ::= [sign] units
  sign      ::= plusminus
  plusminus ::= '+' | '-'
  units     ::= digits [thousands-sep units]
  digits    ::= digit [digits]
</pre>
</blockquote>
<p><b>Rationale:</b></p>
<p>It's not clear whether the format described in 22.2.3.1 <a href="lib-locales.html#lib.locale.numpunct"> [lib.locale.numpunct]</a> paragraph 2 has any normative weight: nothing in the
standard says how, or whether, it's used.  However, there's no reason
for it to differ gratuitously from the very specific description of
numeric processing in 22.2.2.1.2 <a href="lib-locales.html#lib.facet.num.get.virtuals"> [lib.facet.num.get.virtuals]</a>.  The proposed
resolution removes all mention of "whitespace" from that format.</p>
<hr>
<a name="339"><h3>339.&nbsp;definition of bitmask type restricted to clause 27</h3></a><p><b>Section:</b>&nbsp;22.2.1 <a href="lib-locales.html#lib.category.ctype"> [lib.category.ctype]</a>, 17.3.2.1.2 <a href="lib-intro.html#lib.bitmask.types"> [lib.bitmask.types]</a>&nbsp; <b>Status:</b>&nbsp;<a href="lwg-active.html#WP">WP</a>&nbsp; <b>Submitter:</b>&nbsp;Martin Sebor&nbsp; <b>Date:</b>&nbsp;17 September 2001</p>
<p>
The ctype_category::mask type is declared to be an enum in 22.2.1 <a href="lib-locales.html#lib.category.ctype"> [lib.category.ctype]</a> with p1 then stating that it is a bitmask type, most
likely referring to the definition of bitmask type in 17.3.2.1.2 <a href="lib-intro.html#lib.bitmask.types"> [lib.bitmask.types]</a>, p1. However, the said definition only applies to
clause 27, making the reference in 22.2.1 somewhat dubious.
</p>
<p><b>Proposed resolution:</b></p>
<p>Clarify 17.3.2.1.2, p1 by changing the current text from</p>
    <blockquote>
    Several types defined in clause 27 are bitmask types. Each bitmask type
    can be implemented as an enumerated type that overloads certain operators,
    as an integer type, or as a bitset (23.3.5 <a href="lib-containers.html#lib.template.bitset"> [lib.template.bitset]</a>).
    </blockquote>
<p>to read</p>
    <blockquote>
    Several types defined in clauses lib.language.support through 
    lib.input.output and Annex D are bitmask types. Each bitmask type can
    be implemented as an enumerated type that overloads certain operators,
    as an integer  type, or as a bitset (lib.template.bitset).
    </blockquote>

<p>
Additionally, change the definition in 22.2.1 to adopt the same
convention as in clause 27 by replacing the existing text with the
following (note, in particluar, the cross-reference to 17.3.2.1.2 in
22.2.1, p1):
</p>

<blockquote>
<p>22.2.1 The ctype category [lib.category.ctype]</p>
<pre>
namespace std {
    class ctype_base {
    public:
        typedef <b><i>T</i></b> mask;

        // numeric values are for exposition only.
        static const mask space = 1 &lt;&lt; 0;
        static const mask print = 1 &lt;&lt; 1;
        static const mask cntrl = 1 &lt;&lt; 2;
        static const mask upper = 1 &lt;&lt; 3;
        static const mask lower = 1 &lt;&lt; 4;
        static const mask alpha = 1 &lt;&lt; 5;
        static const mask digit = 1 &lt;&lt; 6;
        static const mask punct = 1 &lt;&lt; 7;
        static const mask xdigit = 1 &lt;&lt; 8;
        static const mask alnum = alpha | digit;
        static const mask graph = alnum | punct;
    };
}
</pre>

<p>The type <tt>mask</tt> is a bitmask type (17.3.2.1.2 <a href="lib-intro.html#lib.bitmask.types"> [lib.bitmask.types]</a>).</p>
</blockquote>

<p><i>[Cura&ccedil;ao: The LWG notes that T above should be bold-italics to be
consistent with the rest of the standard.]</i></p>

<hr>
<a name="340"><h3>340.&nbsp;interpretation of <tt>has_facet&lt;Facet&gt;(loc)</tt>
</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#WP">WP</a>&nbsp; <b>Submitter:</b>&nbsp;Martin Sebor&nbsp; <b>Date:</b>&nbsp;18 Sep 2001</p>
<p>
It's unclear whether 22.1.1.1.1, p3 says that
<tt>has_facet&lt;Facet&gt;(loc)</tt> returns true for any <tt>Facet</tt>
from Table 51 or whether it includes Table 52 as well:
</p>

<blockquote>
For any locale <tt>loc</tt> either constructed, or returned by
locale::classic(), and any facet <tt>Facet</tt> that is a member of a
standard category, <tt>has_facet&lt;Facet&gt;(loc)</tt> is true. Each
locale member function which takes a <tt>locale::category</tt>
argument operates on the corresponding set of facets.
</blockquote>

<p>
It seems that it comes down to which facets are considered to be members of a
standard category. Intuitively, I would classify all the facets in Table 52 as
members of their respective standard categories, but there are an unbounded set
of them...
</p>

<p>
The paragraph implies that, for instance, <tt>has_facet&lt;num_put&lt;C,
OutputIterator&gt; &gt;(loc)</tt> must always return true. I don't think that's
possible. If it were, then <tt>use_facet&lt;num_put&lt;C, OutputIterator&gt;
&gt;(loc)</tt> would have to return a reference to a distinct object for each
valid specialization of <tt>num_put&lt;C, OutputIteratory&gt;</tt>, which is
clearly impossible.
</p>

<p>
On the other hand, if none of the facets in Table 52 is a member of a standard
category then none of the locale member functions that operate on entire
categories of facets will work properly.
</p>

<p>
It seems that what p3 should mention that it's required (permitted?)
to hold only for specializations of <tt>Facet</tt> from Table 52 on
<tt>C</tt> from the set { <tt>char</tt>, <tt>wchar_t</tt> }, and
<tt>InputIterator</tt> and <tt>OutputIterator</tt> from the set of
{
{i,o}<tt>streambuf_iterator</tt>&lt;{<tt>char</tt>,<tt>wchar_t</tt>}<tt>&gt;</tt>
}.
</p>
<p><b>Proposed resolution:</b></p>
<p>In 22.1.1.1.1 <a href="lib-locales.html#lib.locale.category"> [lib.locale.category]</a>, paragraph 3, change
"that is a member of a standard category" to "shown in Table 51".</p>
<p><b>Rationale:</b></p>
<p>The facets in Table 52 are an unbounded set.  Locales should not be
required to contain an infinite number of facets.</p> 

<p>It's not necessary to talk about which values of InputIterator and
OutputIterator must be supported.  Table 51 already contains a
complete list of the ones we need.</p>
<hr>
<a name="341"><h3>341.&nbsp;Vector reallocation and swap</h3></a><p><b>Section:</b>&nbsp;23.2.4.2 <a href="lib-containers.html#lib.vector.capacity"> [lib.vector.capacity]</a>&nbsp; <b>Status:</b>&nbsp;<a href="lwg-active.html#WP">WP</a>&nbsp; <b>Submitter:</b>&nbsp;Anthony Williams&nbsp; <b>Date:</b>&nbsp;27 Sep 2001</p>
<p>It is a common idiom to reduce the capacity of a vector by swapping it with
an empty one:</p>
<pre>
  std::vector&lt;SomeType&gt; vec;
  // fill vec with data
  std::vector&lt;SomeType&gt;().swap(vec);
  // vec is now empty, with minimal capacity
</pre>

<p>However, the wording of 23.2.4.2 <a href="lib-containers.html#lib.vector.capacity"> [lib.vector.capacity]</a>paragraph 5 prevents
the capacity of a vector being reduced, following a call to
reserve(). This invalidates the idiom, as swap() is thus prevented
from reducing the capacity. The proposed wording for issue <a href="lwg-defects.html#329">329</a> does not affect this.  Consequently, the example above
requires the temporary to be expanded to cater for the contents of
vec, and the contents be copied across. This is a linear-time
operation.</p>

<p>However, the container requirements state that swap must have constant
complexity (23.1 <a href="lib-containers.html#lib.container.requirements"> [lib.container.requirements]</a> note to table 65).</p>

<p>This is an important issue, as reallocation affects the validity of
references and iterators.</p>

<p>If the wording of 23.2.4.2p5 is taken to be the desired intent, then
references and iterators remain valid after a call to swap, if they refer to
an element before the new end() of the vector into which they originally
pointed, in which case they refer to the element at the same index position.
Iterators and references that referred to an element whose index position
was beyond the new end of the vector are invalidated.</p>

<p>If the note to table 65 is taken as the desired intent, then there are two
possibilities with regard to iterators and references:</p>

<ol>
<li>All Iterators and references into both vectors are invalidated.</li>
<li>Iterators and references into either vector remain valid, and remain
pointing to the same element. Consequently iterators and references that
referred to one vector now refer to the other, and vice-versa.</li>
</ol>
<p><b>Proposed resolution:</b></p>
<p>Add a new paragraph after 23.2.4.2 <a href="lib-containers.html#lib.vector.capacity"> [lib.vector.capacity]</a> paragraph 5:</p>
<blockquote>
<pre>
  void swap(vector&lt;T,Allocator&gt;&amp; x);
</pre>
<p><b>Effects:</b> Exchanges the contents and capacity() of <tt>*this</tt>
with that of <tt>x</tt>.</p>
<p><b>Complexity:</b> Constant time.</p>
</blockquote>

<p><i>[This solves the problem reported for this issue.  We may also
have a problem with a circular definition of swap() for other
containers.]</i></p>

<p><b>Rationale:</b></p>
<p>
swap should be constant time.  The clear intent is that it should just
do pointer twiddling, and that it should exchange all properties of
the two vectors, including their reallocation guarantees.
</p>
<hr>
<a name="345"><h3>345.&nbsp;type tm in &lt;cwchar&gt;</h3></a><p><b>Section:</b>&nbsp;21.4 <a href="lib-strings.html#lib.c.strings"> [lib.c.strings]</a>&nbsp; <b>Status:</b>&nbsp;<a href="lwg-active.html#WP">WP</a>&nbsp; <b>Submitter:</b>&nbsp;Clark Nelson&nbsp; <b>Date:</b>&nbsp;19 Oct 2001</p>
<p>
C99, and presumably amendment 1 to C90, specify that &lt;wchar.h&gt;
declares struct tm as an incomplete type. However, table 48 in 21.4 <a href="lib-strings.html#lib.c.strings"> [lib.c.strings]</a> does not mention the type tm as being declared in
&lt;cwchar&gt;. Is this omission intentional or accidental?
</p>
<p><b>Proposed resolution:</b></p>
<p>In section 21.4 <a href="lib-strings.html#lib.c.strings"> [lib.c.strings]</a>, add "tm" to table 48.</p>
<hr>
<a name="346"><h3>346.&nbsp;Some iterator member functions should be const</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#WP">WP</a>&nbsp; <b>Submitter:</b>&nbsp;Jeremy Siek&nbsp; <b>Date:</b>&nbsp;20 Oct 2001</p>
<p>Iterator member functions and operators that do not change the state
of the iterator should be defined as const member functions or as
functions that take iterators either by const reference or by
value. The standard does not explicitly state which functions should
be const.  Since this a fairly common mistake, the following changes
are suggested to make this explicit.</p>

<p>The tables almost indicate constness properly through naming: r
for non-const and a,b for const iterators. The following changes
make this more explicit and also fix a couple problems.</p>
<p><b>Proposed resolution:</b></p>
<p>In 24.1 <a href="lib-iterators.html#lib.iterator.requirements"> [lib.iterator.requirements]</a> Change the first section of p9 from
"In the following sections, a and b denote values of X..." to
"In the following sections, a and b denote values of type const X...".</p>

<p>In Table 73, change</p>
<pre>
    a-&gt;m   U&amp;         ...
</pre>

<p>to</p>

<pre>
    a-&gt;m   const U&amp;   ...
    r-&gt;m   U&amp;         ...
</pre>

<p>In Table 73 expression column, change</p>

<pre>
    *a = t
</pre>

<p>to</p>

<pre>
    *r = t
</pre>

<p><i>[Redmond: The container requirements should be reviewed to see if
the same problem appears there.]</i></p>

<hr>
<a name="347"><h3>347.&nbsp;locale::category and bitmask requirements</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#WP">WP</a>&nbsp; <b>Submitter:</b>&nbsp;P.J. Plauger, Nathan Myers&nbsp; <b>Date:</b>&nbsp;23 Oct 2001</p>
<p>
In 22.1.1.1.1 <a href="lib-locales.html#lib.locale.category"> [lib.locale.category]</a> paragraph 1, the category members
are described as bitmask elements.  In fact, the bitmask requirements
in 17.3.2.1.2 <a href="lib-intro.html#lib.bitmask.types"> [lib.bitmask.types]</a> don't seem quite right: <tt>none</tt>
and <tt>all</tt> are bitmask constants, not bitmask elements.</p>

<p>In particular, the requirements for <tt>none</tt> interact poorly
with the requirement that the LC_* constants from the C library must
be recognizable as C++ locale category constants.  LC_* values should
not be mixed with these values to make category values.</p>

<p>We have two options for the proposed resolution.  Informally:
option 1 removes the requirement that LC_* values be recognized as
category arguments.  Option 2 changes the category type so that this
requirement is implementable, by allowing <tt>none</tt> to be some
value such as 0x1000 instead of 0.</p>

<p>Nathan writes: "I believe my proposed resolution [Option 2] merely
re-expresses the status quo more clearly, without introducing any
changes beyond resolving the DR.</p>

<p><b>Proposed resolution:</b></p>
<p>Replace the first two paragraphs of 22.1.1.1 <a href="lib-locales.html#lib.locale.types"> [lib.locale.types]</a> with:</p>
<blockquote>
<pre>
    typedef int category;
</pre>

<p>Valid category values include the <tt>locale</tt> member bitmask
elements <tt>collate</tt>, <tt>ctype</tt>, <tt>monetary</tt>,
<tt>numeric</tt>, <tt>time</tt>, and <tt>messages</tt>, each of which
represents a single locale category. In addition, <tt>locale</tt> member
bitmask constant <tt>none</tt> is defined as zero and represents no
category. And locale member bitmask constant <tt>all</tt> is defined such that
the expression</p>
<pre>
    (collate | ctype | monetary | numeric | time | messages | all) == all
</pre>
<p>
is <tt>true</tt>, and represents the union of all categories.  Further
the expression <tt>(X | Y)</tt>, where <tt>X</tt> and <tt>Y</tt> each
represent a single category, represents the union of the two
categories.
</p>

<p>
<tt>locale</tt> member functions expecting a <tt>category</tt>
argument require one of the <tt>category</tt> values defined above, or
the union of two or more such values. Such a <tt>category</tt>
argument identifies a set of locale categories. Each locale category,
in turn, identifies a set of locale facets, including at least those
shown in Table 51:
</p>
</blockquote>
<p><i>[Cura&ccedil;ao: need input from locale experts.]</i></p>

<p><b>Rationale:</b></p>

<p>The LWG considered, and rejected, an alternate proposal (described
  as "Option 2" in the discussion).  The main reason for rejecting it
  was that library implementors were concerened about implementation
  difficult, given that getting a C++ library to work smoothly with a
  separately written C library is already a delicate business.  Some
  library implementers were also concerned about the issue of adding
  extra locale categories.</p>

<blockquote>
<p><b>Option 2:</b> <br>
Replace the first paragraph of 22.1.1.1 <a href="lib-locales.html#lib.locale.types"> [lib.locale.types]</a> with:</p>
<blockquote>
<p>
Valid category values include the enumerated values.  In addition, the
result of applying commutative operators | and &amp; to any two valid 
values is valid, and results in the setwise union and intersection, 
respectively, of the argument categories.  The values <tt>all</tt> and 
<tt>none</tt> are defined such that for any valid value <tt>cat</tt>, the
expressions <tt>(cat | all == all)</tt>, <tt>(cat &amp; all == cat)</tt>,
<tt>(cat | none == cat)</tt> and <tt>(cat &amp; none == none)</tt> are 
true.  For non-equal values <tt>cat1</tt> and <tt>cat2</tt> of the
remaining enumerated values, <tt>(cat1 &amp; cat2 == none)</tt> is true.
For any valid categories <tt>cat1</tt> and <tt>cat2</tt>, the result
of <tt>(cat1 &amp; ~cat2)</tt> is valid, and equals the setwise union of 
those categories found in <tt>cat1</tt> but not found in <tt>cat2</tt>.
[Footnote: it is not required that <tt>all</tt> equal the setwise union
of the other enumerated values; implementations may add extra categories.]
</p>
</blockquote>
</blockquote>
<hr>
<a name="349"><h3>349.&nbsp;Minor typographical error in ostream_iterator</h3></a><p><b>Section:</b>&nbsp;24.5.2 <a href="lib-iterators.html#lib.ostream.iterator"> [lib.ostream.iterator]</a>&nbsp; <b>Status:</b>&nbsp;<a href="lwg-active.html#WP">WP</a>&nbsp; <b>Submitter:</b>&nbsp;Andy Sawyer&nbsp; <b>Date:</b>&nbsp;24 Oct 2001</p>
<p>24.5.2 [lib.ostream.iterator] states:</p>
<pre>
    [...]

    private:
    // basic_ostream&lt;charT,traits&gt;* out_stream; exposition only
    // const char* delim; exposition only
</pre>

<p>Whilst it's clearly marked "exposition only", I suspect 'delim'
should be of type 'const charT*'.</p>
<p><b>Proposed resolution:</b></p>
<p>
In 24.5.2 <a href="lib-iterators.html#lib.ostream.iterator"> [lib.ostream.iterator]</a>, replace <tt>const char* delim</tt> with
<tt>const charT* delim</tt>.
</p>
<hr>
<a name="352"><h3>352.&nbsp;missing fpos requirements</h3></a><p><b>Section:</b>&nbsp;21.1.2 <a href="lib-strings.html#lib.char.traits.typedefs"> [lib.char.traits.typedefs]</a>&nbsp; <b>Status:</b>&nbsp;<a href="lwg-active.html#WP">WP</a>&nbsp; <b>Submitter:</b>&nbsp;Martin Sebor&nbsp; <b>Date:</b>&nbsp;2 Dec 2001</p>
<p>
<i>(1)</i>
There are no requirements on the <tt>stateT</tt> template parameter of
<tt>fpos</tt> listed in 27.4.3. The interface appears to require that
the type be at least Assignable and CopyConstructible (27.4.3.1, p1),
and I think also DefaultConstructible (to implement the operations in
Table 88).
</p>
<p>
21.1.2, p3, however, only requires that
<tt>char_traits&lt;charT&gt;::state_type</tt> meet the requirements of
CopyConstructible types.
</p>
<p>
<i>(2)</i>
Additionally, the <tt>stateT</tt> template argument has no
corresponding typedef in fpos which might make it difficult to use in
generic code.
</p>
<p><b>Proposed resolution:</b></p>
<p>
Modify 21.1.2, p4 from
</p>
<p>
    Requires: <tt>state_type</tt> shall meet the requirements of
              CopyConstructible types (20.1.3).
</p>
<p>
    Requires: state_type shall meet the requirements of Assignable
              (23.1, p4), CopyConstructible (20.1.3), and
              DefaultConstructible  (20.1.4) types.
</p>

<p><b>Rationale:</b></p>
<p>The LWG feels this is two issues, as indicated above. The first is
a defect---std::basic_fstream is unimplementable without these
additional requirements---and the proposed resolution fixes it.  The
second is questionable; who would use that typedef?  The class
template fpos is used only in a very few places, all of which know the
state type already.  Unless motivation is provided, the second should
be considered NAD.</p>
<hr>
<a name="354"><h3>354.&nbsp;Associative container lower/upper bound requirements</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#WP">WP</a>&nbsp; <b>Submitter:</b>&nbsp;Hans Aberg&nbsp; <b>Date:</b>&nbsp;17 Dec 2001</p>
<p>
Discussions in the thread "Associative container lower/upper bound
requirements" on comp.std.c++ suggests that there is a defect in the
C++ standard, Table 69 of section 23.1.2, "Associative containers",
[lib.associative.reqmts].  It currently says:</p>

<blockquote>
<p>
a.find(k): returns an iterator pointing to an element with the key equivalent to
k, or a.end() if such an element is not found.
</p>

<p>
a.lower_bound(k): returns an iterator pointing to the first element with
key not less than k.
</p>

<p>
a.upper_bound(k): returns an iterator pointing to the first element with
key greater than k.
</p>
</blockquote>

<p>
We have "or a.end() if such an element is not found" for
<tt>find</tt>, but not for <tt>upper_bound</tt> or
<tt>lower_bound</tt>.  As the text stands, one would be forced to
insert a new element into the container and return an iterator to that
in case the sought iterator does not exist, which does not seem to be
the intention (and not possible with the "const" versions).
</p>
<p><b>Proposed resolution:</b></p>

<p>Change Table 69 of section 23.1.2 <a href="lib-containers.html#lib.associative.reqmts"> [lib.associative.reqmts]</a> indicated entries
to:</p>

<blockquote>
<p>
a.lower_bound(k): returns an iterator pointing to the first element with
key not less than k, or a.end() if such an element is not found.
</p>

<p>
a.upper_bound(k): returns an iterator pointing to the first element with
key greater than k, or a.end() if such an element is not found.
</p>
</blockquote>

<p><i>[Cura&ccedil;ao: LWG reviewed PR.]</i></p>

<hr>
<a name="355"><h3>355.&nbsp;Operational semantics for a.back()</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#WP">WP</a>&nbsp; <b>Submitter:</b>&nbsp;Yaroslav Mironov&nbsp; <b>Date:</b>&nbsp;23 Jan 2002</p>

<p>Table 68 "Optional Sequence Operations" in 23.1.1/12
specifies operational semantics for "a.back()" as
"*--a.end()", which may be ill-formed <i>[because calling
operator-- on a temporary (the return) of a built-in type is
ill-formed]</i>, provided a.end() returns a simple pointer rvalue
(this is almost always the case for std::vector::end(), for
example). Thus, the specification is not only incorrect, it
demonstrates a dangerous construct: "--a.end()" may
successfully compile and run as intended, but after changing the type
of the container or the mode of compilation it may produce
compile-time error. </p>

<p><b>Proposed resolution:</b></p>
<p>Change the specification in table 68 "Optional Sequence
Operations" in 23.1.1/12 for "a.back()" from</p>


<blockquote>
*--a.end()
</blockquote>

<p>to</p>

<blockquote>
  { iterator tmp = a.end(); --tmp; return *tmp; }
</blockquote>

<p>and the specification for "a.pop_back()" from</p>

<blockquote>
a.erase(--a.end())
</blockquote>

<p>to</p>

<blockquote>
  { iterator tmp = a.end(); --tmp; a.erase(tmp); }
</blockquote>

<p><i>[Cura&ccedil;ao: LWG changed PR from "{ X::iterator tmp =
a.end(); return *--tmp; }" to "*a.rbegin()", and from
"{ X::iterator tmp = a.end(); a.erase(--tmp); }" to
"a.erase(rbegin())".]</i></p>

<p><i>[There is a second possible defect; table 68 "Optional
Sequence Operations" in the "Operational Semantics"
column uses operations present only in the "Reversible
Container" requirements, yet there is no stated dependency
between these separate requirements tables. Ask in Santa Cruz if the
LWG would like a new issue opened.]</i></p>

<p><i>[Santa Cruz: the proposed resolution is even worse than what's in
  the current standard: erase is undefined for reverse iterator.  If
  we're going to make the change, we need to define a temporary and
  use operator--.  Additionally, we don't know how prevalent this is:
  do we need to make this change in more than one place?  Martin has
  volunteered to review the standard and see if this problem occurs
  elsewhere.]</i></p>

<p><i>[Oxford: Matt provided new wording to address the concerns raised
  in Santa Cruz.  It does not appear that this problem appears
  anywhere else in clauses 23 or 24.]</i></p>

<p><i>[Kona: In definition of operational semantics of back(), change
"*tmp" to "return *tmp;"]</i></p>

<hr>
<a name="358"><h3>358.&nbsp;interpreting <tt>thousands_sep</tt> after a <tt>decimal_point</tt>
</h3></a><p><b>Section:</b>&nbsp;22.2.2.1.2 <a href="lib-locales.html#lib.facet.num.get.virtuals"> [lib.facet.num.get.virtuals]</a>&nbsp; <b>Status:</b>&nbsp;<a href="lwg-active.html#WP">WP</a>&nbsp; <b>Submitter:</b>&nbsp;Martin Sebor&nbsp; <b>Date:</b>&nbsp;12 Mar 2002</p>
<p>
I don't think <tt>thousands_sep</tt> is being treated correctly after
decimal_point has been seen. Since grouping applies only to the
integral part of the number, the first such occurrence should, IMO,
terminate Stage 2. (If it does not terminate it, then 22.2.2.1.2, p12
and 22.2.3.1.2, p3 need to explain how <tt>thousands_sep</tt> is to be
interpreted in the fractional part of a number.)
</p>

<p>
The easiest change I can think of that resolves this issue would be
something like below.
</p>
<p><b>Proposed resolution:</b></p>
<p>
Change the first sentence of 22.2.2.1.2, p9 from
</p>

<blockquote>
    If discard is true then the position of the character is
    remembered, but the character is otherwise ignored. If it is not
    discarded, then a check is made to determine if c is allowed as
    the next character of an input field of the conversion specifier
    returned by stage 1. If so it is accumulated.
</blockquote>

<p>to</p>

<blockquote>
    If <tt>discard</tt> is true, then if <tt>'.'</tt> has not yet been
    accumulated, then the position of the character is remembered, but
    the character is otherwise ignored. Otherwise, if <tt>'.'</tt> has
    already been accumulated, the character is discarded and Stage 2
     terminates. ...
</blockquote>

<p><b>Rationale:</b></p>
<p>We believe this reflects the intent of the Standard.  Thousands sep
  characters after the decimal point are not useful in any locale.
  Some formatting conventions do group digits that follow the decimal
  point, but they usually introduce a different grouping character
  instead of reusing the thousand sep character.  If we want to add
  support for such conventions, we need to do so explicitly.</p>

<hr>
<a name="359"><h3>359.&nbsp;num_put&lt;&gt;::do_put (..., bool) undocumented</h3></a><p><b>Section:</b>&nbsp;22.2.2.2.1 <a href="lib-locales.html#lib.facet.num.put.members"> [lib.facet.num.put.members]</a>&nbsp; <b>Status:</b>&nbsp;<a href="lwg-active.html#WP">WP</a>&nbsp; <b>Submitter:</b>&nbsp;Martin Sebor&nbsp; <b>Date:</b>&nbsp;12 Mar 2002</p>
<p>22.2.2.2.1, p1:</p>

    <pre>
    iter_type put (iter_type out, ios_base&amp; str, char_type fill,
                   bool val) const;
    ...

    1   Returns: do_put (out, str, fill, val).
    </pre>

<p>AFAICS, the behavior of do_put (..., bool) is not documented anywhere,
however, 22.2.2.2.2, p23:</p>

<blockquote>
<pre>
iter_type put (iter_type out, ios_base&amp; str, char_type fill,
               bool val) const;
</pre>


        Effects: If (str.flags() &amp; ios_base::boolalpha) == 0 then do
             out = do_put(out, str, fill, (int)val)
           Otherwise do
<pre>
             string_type s =
                 val ? use_facet&lt;ctype&lt;charT&gt; &gt;(loc).truename()
                     : use_facet&lt;ctype&lt;charT&gt; &gt;(loc).falsename();
</pre>
           and then insert the characters of s into out. <i>out</i>.
</blockquote>

<p>
This means that the bool overload of <tt>do_put()</tt> will never be called,
which contradicts the first paragraph. Perhaps the declaration
should read <tt>do_put()</tt>, and not <tt>put()</tt>?
</p>

<p>
Note also that there is no <b>Returns</b> clause for this function, which
should probably be corrected, just as should the second occurrence
of <i>"out."</i> in the text.
</p>

<p>
I think the least invasive change to fix it would be something like
the following:
</p>
<p><b>Proposed resolution:</b></p>
<p>In 22.2.2.2.2 <a href="lib-locales.html#lib.facet.num.put.virtuals"> [lib.facet.num.put.virtuals]</a>, just above paragraph 1, remove
  the <tt>bool</tt> overload.</p>

<p>
In 22.2.2.2.2 <a href="lib-locales.html#lib.facet.num.put.virtuals"> [lib.facet.num.put.virtuals]</a>, p23, make the following changes
</p>

<blockquote>
     Replace <tt>put()</tt> with <tt>do_put()</tt> in the declaration
     of the member function.
</blockquote>

<blockquote>
    Change the <b>Effects</b> clause to a <b>Returns</b> clause (to
    avoid the requirement to call <tt>do_put(..., int)</tt> from <tt>
    do_put (..., bool))</tt>
    like so:
</blockquote>

<blockquote>
    23   <b>Returns</b>: If <tt>(str.flags() &amp;
         ios_base::boolalpha) == 0</tt> then
         <tt>do_put (out, str, fill, (long)val)</tt>
         Otherwise the function obtains a string <tt>s</tt> as if by
<pre>
             string_type s =
                val ? use_facet&lt;ctype&lt;charT&gt; &gt;(loc).truename()
                    : use_facet&lt;ctype&lt;charT&gt; &gt;(loc).falsename();
</pre>
         and then inserts each character <tt>c</tt> of s into out via
           <tt>*out++ = c</tt>
         and returns <tt>out</tt>.
</blockquote>

<p><b>Rationale:</b></p>
<p>
This fixes a couple of obvious typos, and also fixes what appears to
be a requirement of gratuitous inefficiency.
</p>
<hr>
<a name="360"><h3>360.&nbsp;locale mandates inefficient implementation</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#WP">WP</a>&nbsp; <b>Submitter:</b>&nbsp;Martin Sebor&nbsp; <b>Date:</b>&nbsp;12 Mar 2002</p>
<p>
22.1.1, p7 (copied below) allows iostream formatters and extractors
to make assumptions about the values returned from facet members.
However, such assumptions are apparently not guaranteed to hold
in other cases (e.g., when the facet members are being called directly
rather than as a result of iostream calls, or between successive
calls to the same iostream functions with no interevening calls to
<tt>imbue()</tt>, or even when the facet member functions are called
from other member functions of other facets). This restriction
prevents locale from being implemented efficiently.
</p>
<p><b>Proposed resolution:</b></p>
<p>Change the first sentence in 22.1.1, p7 from</p>
<blockquote>
    In successive calls to a locale facet member function during
    a call to an iostream inserter or extractor or a streambuf member
    function, the returned result shall be identical. [Note: This
    implies that such results may safely be reused without calling
    the locale facet member function again, and that member functions
    of iostream classes cannot safely call <tt>imbue()</tt>
    themselves, except as specified elsewhere. --end note]
</blockquote>

<p>to</p>

<blockquote>
    In successive calls to a locale facet member function on a facet
    object installed in the same locale, the returned result shall be
    identical. ...
</blockquote>

<p><b>Rationale:</b></p>
<p>This change is reasonable becuase it clarifies the intent of this
  part of the standard.</p>
<hr>
<a name="363"><h3>363.&nbsp;Missing exception specification in 27.4.2.1.1</h3></a><p><b>Section:</b>&nbsp;27.4.2.1.1 <a href="lib-iostreams.html#lib.ios::failure"> [lib.ios::failure]</a>&nbsp; <b>Status:</b>&nbsp;<a href="lwg-active.html#WP">WP</a>&nbsp; <b>Submitter:</b>&nbsp;Walter Brown and Marc Paterno&nbsp; <b>Date:</b>&nbsp;20 May 2002</p>
<p>
The destructor of ios_base::failure should have an empty throw
specification, because the destructor of its base class, exception, is
declared in this way.
</p>
<p><b>Proposed resolution:</b></p>
<p>Change the destructor to</p>
<pre>
  virtual ~failure() throw();
</pre>
<p><b>Rationale:</b></p>
<p>Fixes an obvious glitch.  This is almost editorial.</p>
<hr>
<a name="364"><h3>364.&nbsp;Inconsistent wording in 27.5.2.4.2</h3></a><p><b>Section:</b>&nbsp;27.5.2.4.2 <a href="lib-iostreams.html#lib.streambuf.virt.buffer"> [lib.streambuf.virt.buffer]</a>&nbsp; <b>Status:</b>&nbsp;<a href="lwg-active.html#WP">WP</a>&nbsp; <b>Submitter:</b>&nbsp;Walter Brown, Marc Paterno&nbsp; <b>Date:</b>&nbsp;10 May 2002</p>
<p>
27.5.2.4.2 <a href="lib-iostreams.html#lib.streambuf.virt.buffer"> [lib.streambuf.virt.buffer]</a> paragraph 1 is inconsistent with the Effects
clause for seekoff.
</p>
<p><b>Proposed resolution:</b></p>
<p>
Make this paragraph, the Effects clause for setbuf, consistent in wording
with the Effects clause for seekoff in paragraph 3 by amending paragraph 1
to indicate the purpose of setbuf:
</p>

<p>Original text:</p>

<blockquote>
1 Effects: Performs an operation that is defined separately for each
class derived from basic_streambuf in this clause (27.7.1.3, 27.8.1.4).
</blockquote>

<p>Proposed text:</p>

<blockquote>
1 Effects: Influences stream buffering in a way that is defined separately
for each class derived from basic_streambuf in this clause
(27.7.1.3, 27.8.1.4).
</blockquote>

<p><b>Rationale:</b></p>
<p>The LWG doesn't believe there is any normative difference between
  the existing wording and what's in the proposed resolution, but the
  change may make the intent clearer.</p>
<hr>
<a name="365"><h3>365.&nbsp;Lack of const-qualification in clause 27</h3></a><p><b>Section:</b>&nbsp;27 <a href="lib-iostreams.html#lib.input.output"> [lib.input.output]</a>&nbsp; <b>Status:</b>&nbsp;<a href="lwg-active.html#WP">WP</a>&nbsp; <b>Submitter:</b>&nbsp;Walter Brown, Marc Paterno&nbsp; <b>Date:</b>&nbsp;10 May 2002</p>
<p>
Some stream and streambuf member functions are declared non-const,
even thought they appear only to report information rather than to
change an object's logical state.  They should be declared const.  See
document N1360 for details and rationale.
</p>

<p>The list of member functions under discussion: <tt>in_avail</tt>,
<tt>showmanyc</tt>, <tt>tellg</tt>, <tt>tellp</tt>, <tt>is_open</tt>.</p>

<p>Related issue: <a href="lwg-closed.html#73">73</a></p>

<p><b>Proposed resolution:</b></p>
<p>In 27.8.1.5, 27.8.1.7, 27.8.1.8, 27.8.1.10, 27.8.1.11, and 27.8.1.13</p>
<p>Replace</p>
<pre>
  bool is_open();
</pre>
<p>with</p>
<pre>
  bool is_open() const;
</pre>
<p><b>Rationale:</b></p>
<p>Of the changes proposed in N1360, the only one that is safe is
changing the filestreams' is_open to const.  The LWG believed that
this was NAD the first time it considered this issue (issue <a href="lwg-closed.html#73">73</a>), but now thinks otherwise.  The corresponding streambuf
member function, after all,is already const.</p>

<p>The other proposed changes are less safe, because some streambuf
functions that appear merely to report a value do actually perform
mutating operations.  It's not even clear that they should be
considered "logically const", because streambuf has two interfaces, a
public one and a protected one.  These functions may, and often do,
change the state as exposed by the protected interface, even if the
state exposed by the public interface is unchanged.</p>

<p>Note that implementers can make this change in a binary compatible
way by providing both overloads; this would be a conforming extension.</p>

<hr>
<a name="370"><h3>370.&nbsp;Minor error in basic_istream::get</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#WP">WP</a>&nbsp; <b>Submitter:</b>&nbsp;Ray Lischner&nbsp; <b>Date:</b>&nbsp;15 Jul 2002</p>
<p>Defect report for description of basic_istream::get (section 27.6.1.3 <a href="lib-iostreams.html#lib.istream.unformatted"> [lib.istream.unformatted]</a>), paragraph 15. The description for the get function
with the following signature:</p>

<pre>
  basic_istream&lt;charT,traits&gt;&amp; get(basic_streambuf&lt;char_type,traits&gt;&amp;
  sb);
</pre>

<p>is incorrect. It reads</p>

<blockquote>
  Effects: Calls get(s,n,widen('\n'))
</blockquote>

<p>which I believe should be:</p>

<blockquote>
  Effects: Calls get(sb,widen('\n'))
</blockquote>
<p><b>Proposed resolution:</b></p>
<p>Change the <b>Effects</b> paragraph to:</p>
<blockquote>
  Effects: Calls get(sb,this-&gt;widen('\n'))
</blockquote>

<p><i>[Pre-Oxford: Minor correction from Howard: replaced 'widen' 
      with 'this-&gt;widen'.]</i></p>

<p><b>Rationale:</b></p>
<p>Fixes an obvious typo.</p>
<hr>
<a name="373"><h3>373.&nbsp;Are basic_istream and basic_ostream to use (exceptions()&amp;badbit) != 0 ?</h3></a><p><b>Section:</b>&nbsp;27.6.1.2.1 <a href="lib-iostreams.html#lib.istream.formatted.reqmts"> [lib.istream.formatted.reqmts]</a>, 27.6.2.5.1 <a href="lib-iostreams.html#lib.ostream.formatted.reqmts"> [lib.ostream.formatted.reqmts]</a>&nbsp; <b>Status:</b>&nbsp;<a href="lwg-active.html#WP">WP</a>&nbsp; <b>Submitter:</b>&nbsp;Keith Baker&nbsp; <b>Date:</b>&nbsp;23 Jul 2002</p>

<p>
In 27.6.1.2.1 <a href="lib-iostreams.html#lib.istream.formatted.reqmts"> [lib.istream.formatted.reqmts]</a> and 27.6.2.5.1 <a href="lib-iostreams.html#lib.ostream.formatted.reqmts"> [lib.ostream.formatted.reqmts]</a>
(exception()&amp;badbit) != 0 is used in testing for rethrow, yet
exception() is the constructor to class std::exception in 18.6.1 <a href="lib-support.html#lib.exception"> [lib.exception]</a> that has no return type. Should member function
exceptions() found in 27.4.4 <a href="lib-iostreams.html#lib.ios"> [lib.ios]</a> be used instead?
</p>

<p><b>Proposed resolution:</b></p>
<p>
In 27.6.1.2.1 <a href="lib-iostreams.html#lib.istream.formatted.reqmts"> [lib.istream.formatted.reqmts]</a> and 27.6.2.5.1 <a href="lib-iostreams.html#lib.ostream.formatted.reqmts"> [lib.ostream.formatted.reqmts]</a>, change
"(exception()&amp;badbit) != 0" to "(exceptions()&amp;badbit) != 0".
</p>
<p><b>Rationale:</b></p>
<p>Fixes an obvious typo.</p>
<hr>
<a name="375"><h3>375.&nbsp;basic_ios should be ios_base in 27.7.1.3</h3></a><p><b>Section:</b>&nbsp;27.7.1.3 <a href="lib-iostreams.html#lib.stringbuf.virtuals"> [lib.stringbuf.virtuals]</a>&nbsp; <b>Status:</b>&nbsp;<a href="lwg-active.html#WP">WP</a>&nbsp; <b>Submitter:</b>&nbsp;Ray Lischner&nbsp; <b>Date:</b>&nbsp;14 Aug 2002</p>
<p>
In Section 27.7.1.3 <a href="lib-iostreams.html#lib.stringbuf.virtuals"> [lib.stringbuf.virtuals]</a>: Table 90, Table 91, and paragraph
14 all contain references to "basic_ios::" which should be
"ios_base::".
</p>
<p><b>Proposed resolution:</b></p>
<p>
Change all references to "basic_ios" in Table 90, Table 91, and
paragraph 14 to "ios_base".
</p>
<p><b>Rationale:</b></p>
<p>Fixes an obvious typo.</p>
<hr>
<a name="379"><h3>379.&nbsp;nonsensical ctype::do_widen() requirement</h3></a><p><b>Section:</b>&nbsp;22.2.1.1.2 <a href="lib-locales.html#lib.locale.ctype.virtuals"> [lib.locale.ctype.virtuals]</a>&nbsp; <b>Status:</b>&nbsp;<a href="lwg-active.html#WP">WP</a>&nbsp; <b>Submitter:</b>&nbsp;Martin Sebor&nbsp; <b>Date:</b>&nbsp;6 Sep 2002</p>
<p>
The last sentence in 22.2.1.1.2, p11 below doesn't seem to make sense.
</p>
<pre>
  charT do_widen (char c) const;

  -11- Effects: Applies the simplest reasonable transformation from
       a char value or sequence of char values to the corresponding
       charT value or values. The only characters for which unique
       transformations are required are those in the basic source
       character set (2.2). For any named ctype category with a
       ctype&lt;charT&gt; facet ctw and valid ctype_base::mask value
       M (is(M, c) || !ctw.is(M, do_widen(c))) is true.
</pre>
<p>
Shouldn't the last sentence instead read
</p>
<pre>
       For any named ctype category with a ctype&lt;char&gt; facet ctc
       and valid ctype_base::mask value M
       (ctc.is(M, c) || !is(M, do_widen(c))) is true.
</pre>
<p>
I.e., if the narrow character c is not a member of a class of
characters then neither is the widened form of c. (To paraphrase
footnote 224.)
</p>
<p><b>Proposed resolution:</b></p>
<p>
Replace the last sentence of 22.2.1.1.2 <a href="lib-locales.html#lib.locale.ctype.virtuals"> [lib.locale.ctype.virtuals]</a>, p11 with the
following text:
</p>
<pre>
       For any named ctype category with a ctype&lt;char&gt; facet ctc
       and valid ctype_base::mask value M,
       (ctc.is(M, c) || !is(M, do_widen(c))) is true.
</pre>

<p><i>[Kona: Minor edit. Added a comma after the <i>M</i> for clarity.]</i></p>

<p><b>Rationale:</b></p>
<p>The LWG believes this is just a typo, and that this is the correct fix.</p>
<hr>
<a name="380"><h3>380.&nbsp;typos in codecvt tables 53 and 54</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#WP">WP</a>&nbsp; <b>Submitter:</b>&nbsp;Martin Sebor&nbsp; <b>Date:</b>&nbsp;6 Sep 2002</p>
<p>
Tables 53 and 54 in 22.2.1.5.2 <a href="lib-locales.html#lib.locale.codecvt.virtuals"> [lib.locale.codecvt.virtuals]</a> are both titled "convert
result values," when surely "do_in/do_out result values" must have
been intended for Table 53 and "do_unshift result values" for Table
54.
</p>
<p>
Table 54, row 3 says that the meaning of partial is "more characters
needed to be supplied to complete termination." The function is not
supplied any characters, it is given a buffer which it fills with
characters or, more precisely, destination elements (i.e., an escape
sequence). So partial means that space for more than (to_limit - to)
destination elements was needed to terminate a sequence given the
value of state.
</p>
<p><b>Proposed resolution:</b></p>
<p>
Change the title of Table 53 to "do_in/do_out result values" and
the title of Table 54 to "do_unshift result values."
</p>
<p>
Change the text in Table 54, row 3 (the <b>partial</b> row), under the
heading Meaning, to "space for more than (to_limit - to) destination
elements was needed to terminate a sequence given the value of state."
</p>
<hr>
<a name="381"><h3>381.&nbsp;detection of invalid mbstate_t in codecvt</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#WP">WP</a>&nbsp; <b>Submitter:</b>&nbsp;Martin Sebor&nbsp; <b>Date:</b>&nbsp;6 Sep 2002</p>
<p>
All but one codecvt member functions that take a state_type argument
list as one of their preconditions that the state_type argument have
a valid value. However, according to 22.2.1.5.2, p6,
codecvt::do_unshift() is the only codecvt member that is supposed to
return error if the state_type object is invalid.
</p>

<p>
It seems to me that the treatment of state_type by all codecvt member
functions should be the same and the current requirements should be
changed. Since the detection of invalid state_type values may be
difficult in general or computationally expensive in some specific
cases, I propose the following:
</p>
<p><b>Proposed resolution:</b></p>
<p>
Add a new paragraph before 22.2.1.5.2, p5, and after the function
declaration below
</p>
<pre>
    result do_unshift(stateT&amp; state,
    externT* to, externT* to_limit, externT*&amp; to_next) const;
</pre>
<p>
as follows:
</p>
<pre>
    Requires: (to &lt;= to_end) well defined and true; state initialized,
    if at the beginning of a sequence, or else equal to the result of
    converting the preceding characters in the sequence.
</pre>
<p>
and change the text in Table 54, row 4, the <b>error</b> row, under
the heading Meaning, from
</p>
<pre>
    state has invalid value
</pre>
<p>
to
</p>
<pre>
    an unspecified error has occurred
</pre>
<p><b>Rationale:</b></p>
<p>The intent is that implementations should not be required to detect
invalid state values; such a requirement appears nowhere else.  An
invalid state value is a precondition violation, <i>i.e.</i> undefined
behavior.  Implementations that do choose to detect invalid state
values, or that choose to detect any other kind of error, may return
<b>error</b> as an indication.</p>
<hr>
<a name="383"><h3>383.&nbsp;Bidirectional iterator assertion typo</h3></a><p><b>Section:</b>&nbsp;24.1.4 <a href="lib-iterators.html#lib.bidirectional.iterators"> [lib.bidirectional.iterators]</a>&nbsp; <b>Status:</b>&nbsp;<a href="lwg-active.html#WP">WP</a>&nbsp; <b>Submitter:</b>&nbsp;ysapir (submitted via comp.std.c++)&nbsp; <b>Date:</b>&nbsp;17 Oct 2002</p>
<p>
Following a discussion on the boost list regarding end iterators and
the possibility of performing operator--() on them, it seems to me
that there is a typo in the standard.  This typo has nothing to do
with that discussion.
</p>

<p>
I have checked this newsgroup, as well as attempted a search of the
Active/Defect/Closed Issues List on the site for the words "s is
derefer" so I believe this has not been proposed before.  Furthermore,
the "Lists by Index" mentions only DR <a href="lwg-active.html#299">299</a> on section
24.1.4, and DR <a href="lwg-active.html#299">299</a> is not related to this issue.
</p>

<p>
The standard makes the following assertion on bidirectional iterators,
in section 24.1.4 [lib.bidirectional.iterators], Table 75:
</p>

<pre>
                         operational  assertion/note
expression  return type   semantics    pre/post-condition

--r          X&amp;                        pre: there exists s such
                                       that r == ++s.
                                       post: s is dereferenceable.
                                       --(++r) == r.
                                       --r == --s implies r == s.
                                       &amp;r == &amp;--r.
</pre>

<p>
(See <a href="http://aspn.activestate.com/ASPN/Mail/Message/boost/1395763">http://aspn.activestate.com/ASPN/Mail/Message/boost/1395763</a>.)
</p>

<p>
In particular, "s is dereferenceable" seems to be in error.  It seems
that the intention was to say "r is dereferenceable".
</p>

<p>
If it were to say "r is dereferenceable" it would
make perfect sense.  Since s must be dereferenceable prior to
operator++, then the natural result of operator-- (to undo operator++)
would be to make r dereferenceable.  Furthermore, without other
assertions, and basing only on precondition and postconditions, we
could not otherwise know this.  So it is also interesting information.
</p>

<p><b>Proposed resolution:</b></p>
<p>
Change the guarantee to "postcondition: r is dereferenceable."
</p>
<p><b>Rationale:</b></p>
<p>Fixes an obvious typo</p>
<hr>
<a name="389"><h3>389.&nbsp;Const overload of valarray::operator[] returns by value</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#WP">WP</a>&nbsp; <b>Submitter:</b>&nbsp;Gabriel Dos Reis&nbsp; <b>Date:</b>&nbsp;8 Nov 2002</p>
<p>Consider the following program:</p>
<pre>
    #include &lt;iostream&gt;
    #include &lt;ostream&gt;
    #include &lt;vector&gt;
    #include &lt;valarray&gt;
    #include &lt;algorithm&gt;
    #include &lt;iterator&gt;
    template&lt;typename Array&gt;
    void print(const Array&amp; a)
    {
    using namespace std;
    typedef typename Array::value_type T;
    copy(&amp;a[0], &amp;a[0] + a.size(),
    ostream_iterator&lt;T&gt;(std::cout, " "));
    }
    template&lt;typename T, unsigned N&gt;
    unsigned size(T(&amp;)[N]) { return N; }
    int main()
    {
    double array[] = { 0.89, 9.3, 7, 6.23 };
    std::vector&lt;double&gt; v(array, array + size(array));
    std::valarray&lt;double&gt; w(array, size(array));
    print(v); // #1
    std::cout &lt;&lt; std::endl;
    print(w); // #2
    std::cout &lt;&lt; std::endl;
    }
</pre>

<p>While the call numbered #1 succeeds, the call numbered #2 fails
because the const version of the member function
valarray&lt;T&gt;::operator[](size_t) returns a value instead of a
const-reference. That seems to be so for no apparent reason, no
benefit. Not only does that defeats users' expectation but it also
does hinder existing software (written either in C or Fortran)
integration within programs written in C++.  There is no reason why
subscripting an expression of type valarray&lt;T&gt; that is const-qualified
should not return a const T&amp;.</p>
<p><b>Proposed resolution:</b></p>
<p>In the class synopsis in 26.3.2 <a href="lib-numerics.html#lib.template.valarray"> [lib.template.valarray]</a>, and in
26.3.2.3 <a href="lib-numerics.html#lib.valarray.access"> [lib.valarray.access]</a> just above paragraph 1, change</p>
<pre>
  T operator[](size_t const);
</pre>
<p>to</p>
<pre>
  const T&amp; operator[](size_t const);
</pre>

<p><i>[Kona: fixed a minor typo: put semicolon at the end of the line
  wehre it belongs.]</i></p>

<p><b>Rationale:</b></p>
<p>Return by value seems to serve no purpose.  Valaray was explicitly
designed to have a specified layout so that it could easily be
integrated with libraries in other languages, and return by value
defeats that purpose.  It is believed that this change will have no
impact on allowable optimizations.</p>
<hr>
<a name="391"><h3>391.&nbsp;non-member functions specified as const</h3></a><p><b>Section:</b>&nbsp;22.1.3.2 <a href="lib-locales.html#lib.conversions"> [lib.conversions]</a>&nbsp; <b>Status:</b>&nbsp;<a href="lwg-active.html#WP">WP</a>&nbsp; <b>Submitter:</b>&nbsp;James Kanze&nbsp; <b>Date:</b>&nbsp;10 Dec 2002</p>
<p>
The specifications of toupper and tolower both specify the functions as
const, althought they are not member functions, and are not specified as
const in the header file synopsis in section 22.1 <a href="lib-locales.html#lib.locales"> [lib.locales]</a>.
</p>
<p><b>Proposed resolution:</b></p>
<p>In 22.1.3.2 <a href="lib-locales.html#lib.conversions"> [lib.conversions]</a>, remove <tt>const</tt> from the function
  declarations of std::toupper and std::tolower</p>
<p><b>Rationale:</b></p>
<p>Fixes an obvious typo</p>
<hr>
<a name="395"><h3>395.&nbsp;inconsistencies in the definitions of rand() and random_shuffle()</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#WP">WP</a>&nbsp; <b>Submitter:</b>&nbsp;James Kanze&nbsp; <b>Date:</b>&nbsp;3 Jan 2003</p>
<p>
In 26.5 <a href="lib-numerics.html#lib.c.math"> [lib.c.math]</a>, the C++ standard refers to the C standard for the
definition of rand(); in the C standard, it is written that "The
implementation shall behave as if no library function calls the rand
function."
</p>

<p>
In 25.2.11 <a href="lib-algorithms.html#lib.alg.random.shuffle"> [lib.alg.random.shuffle]</a>, there is no specification as to
how the two parameter version of the function generates its random
value.  I believe that all current implementations in fact call rand()
(in contradiction with the requirement avove); if an implementation does
not call rand(), there is the question of how whatever random generator
it does use is seeded.  Something is missing.
</p>

<p><b>Proposed resolution:</b></p>
<p>
In [lib.c.math], add a paragraph specifying that the C definition of
rand shal be modified to say that "Unless otherwise specified, the
implementation shall behave as if no library function calls the rand
function."
</p>

<p>
In [lib.alg.random.shuffle], add a sentence to the effect that "In
the two argument form of the function, the underlying source of
random numbers is implementation defined. [Note: in particular, an
implementation is permitted to use <tt>rand</tt>.]
</p>
<p><b>Rationale:</b></p>
<p>The original proposed resolution proposed requiring the
  two-argument from of <tt>random_shuffle</tt> to
  use <tt>rand</tt>. We don't want to do that, because some existing
  implementations already use something else: gcc
  uses <tt>lrand48</tt>, for example.  Using <tt>rand</tt> presents a
  problem if the number of elements in the sequence is greater than
  RAND_MAX.</p> 
<hr>
<a name="400"><h3>400.&nbsp;redundant type cast in lib.allocator.members</h3></a><p><b>Section:</b>&nbsp;20.4.1.1 <a href="lib-utilities.html#lib.allocator.members"> [lib.allocator.members]</a>&nbsp; <b>Status:</b>&nbsp;<a href="lwg-active.html#WP">WP</a>&nbsp; <b>Submitter:</b>&nbsp;Markus Mauhart&nbsp; <b>Date:</b>&nbsp;27 Feb 2003</p>
<p>
20.4.1.1 <a href="lib-utilities.html#lib.allocator.members"> [lib.allocator.members]</a> allocator members, contains
the following 3 lines:
</p>

<pre>
  12 Returns: new((void *) p) T( val)
     void destroy(pointer p);
  13 Returns: ((T*) p)-&gt;~T()
</pre>

<p>
The type cast "(T*) p" in the last line is redundant cause
we know that std::allocator&lt;T&gt;::pointer is a typedef for T*.
</p>
<p><b>Proposed resolution:</b></p>
<p>
Replace "((T*) p)" with "p".
</p>
<p><b>Rationale:</b></p>
<p>Just a typo, this is really editorial.</p>
<hr>
<a name="402"><h3>402.&nbsp;wrong new expression in [some_]allocator::construct</h3></a><p><b>Section:</b>&nbsp;20.1.5 <a href="lib-utilities.html#lib.allocator.requirements"> [lib.allocator.requirements]</a>, 20.4.1.1 <a href="lib-utilities.html#lib.allocator.members"> [lib.allocator.members]</a>, &nbsp; <b>Status:</b>&nbsp;<a href="lwg-active.html#WP">WP</a>&nbsp; <b>Submitter:</b>&nbsp;Markus Mauhart&nbsp; <b>Date:</b>&nbsp;27 Feb 2003</p>
<p>
This applies to the new expression that is contained in both par12 of
20.4.1.1 <a href="lib-utilities.html#lib.allocator.members"> [lib.allocator.members]</a> and in par2 (table 32) of 20.1.5 <a href="lib-utilities.html#lib.allocator.requirements"> [lib.allocator.requirements]</a>.
I think this new expression is wrong, involving unintended side
effects.
</p>


<p>20.4.1.1 <a href="lib-utilities.html#lib.allocator.members"> [lib.allocator.members]</a>  contains the following 3 lines:</p>

<pre>
  11 Returns: the largest value N for which the call allocate(N,0) might succeed.
     void construct(pointer p, const_reference val);
  12 Returns: new((void *) p) T( val)
</pre>


<p>20.1.5 <a href="lib-utilities.html#lib.allocator.requirements"> [lib.allocator.requirements]</a> in table 32 has the following line:</p>
<pre>
  a.construct(p,t)   Effect: new((void*)p) T(t)
</pre>

<p>
.... with the prerequisits coming from the preceding two paragraphs,
especially from table 31:
</p>

<pre>
  alloc&lt;T&gt;             a     ;// an allocator for T
  alloc&lt;T&gt;::pointer    p     ;// random access iterator
                              // (may be different from T*)
  alloc&lt;T&gt;::reference  r = *p;// T&amp;
  T const&amp;             t     ;
</pre>

<p>
Cause of using "new" but not "::new", any existing "T::operator new"
function will hide the global placement new function. When there is no
"T::operator new" with adequate signature,
every_alloc&lt;T&gt;::construct(..) is ill-formed, and most
std::container&lt;T,every_alloc&lt;T&gt;&gt; use it; a workaround
would be adding placement new and delete functions with adequate
signature and semantic to class T, but class T might come from another
party. Maybe even worse is the case when T has placement new and
delete functions with adequate signature but with "unknown" semantic:
I dont like to speculate about it, but whoever implements
any_container&lt;T,any_alloc&gt; and wants to use construct(..)
probably must think about it.
</p>
<p><b>Proposed resolution:</b></p>
<p>
Replace "new" with "::new" in both cases.
</p>
<hr>
<a name="403"><h3>403.&nbsp;basic_string::swap should not throw exceptions</h3></a><p><b>Section:</b>&nbsp;21.3.5.8 <a href="lib-strings.html#lib.string::swap"> [lib.string::swap]</a>&nbsp; <b>Status:</b>&nbsp;<a href="lwg-active.html#WP">WP</a>&nbsp; <b>Submitter:</b>&nbsp;Beman Dawes&nbsp; <b>Date:</b>&nbsp;25 Mar 2003</p>

<p>
std::basic_string, 21.3 <a href="lib-strings.html#lib.basic.string"> [lib.basic.string]</a> paragraph 2 says that
basic_string "conforms to the requirements of a Sequence, as specified
in (23.1.1)." The sequence requirements specified in (23.1.1) to not
include any prohibition on swap members throwing exceptions.
</p>

<p>
Section 23.1 <a href="lib-containers.html#lib.container.requirements"> [lib.container.requirements]</a> paragraph 10 does limit conditions under
which exceptions may be thrown, but applies only to "all container
types defined in this clause" and so excludes basic_string::swap
because it is defined elsewhere.
</p>

<p>
Eric Niebler points out that 21.3 <a href="lib-strings.html#lib.basic.string"> [lib.basic.string]</a> paragraph 5 explicitly
permits basic_string::swap to invalidates iterators, which is
disallowed by 23.1 <a href="lib-containers.html#lib.container.requirements"> [lib.container.requirements]</a> paragraph 10. Thus the standard would
be contradictory if it were read or extended to read as having
basic_string meet 23.1 <a href="lib-containers.html#lib.container.requirements"> [lib.container.requirements]</a> paragraph 10 requirements.
</p>

<p>
Yet several LWG members have expressed the belief that the original
intent was that basic_string::swap should not throw exceptions as
specified by 23.1 <a href="lib-containers.html#lib.container.requirements"> [lib.container.requirements]</a> paragraph 10, and that the standard is
unclear on this issue. The complexity of basic_string::swap is
specified as "constant time", indicating the intent was to avoid
copying (which could cause a bad_alloc or other exception). An
important use of swap is to ensure that exceptions are not thrown in
exception-safe code.
</p>

<p>
Note: There remains long standing concern over whether or not it is
possible to reasonably meet the 23.1 <a href="lib-containers.html#lib.container.requirements"> [lib.container.requirements]</a> paragraph 10 swap
requirements when allocators are unequal. The specification of
basic_string::swap exception requirements is in no way intended to
address, prejudice, or otherwise impact that concern.
</p>





<p><b>Proposed resolution:</b></p>
<p>
In 21.3.5.8 <a href="lib-strings.html#lib.string::swap"> [lib.string::swap]</a>, add a throws clause:
</p>

<p>
Throws: Shall not throw exceptions.
</p>
<hr>
<a name="404"><h3>404.&nbsp;May a replacement allocation function be declared inline?</h3></a><p><b>Section:</b>&nbsp;17.4.3.4 <a href="lib-intro.html#lib.replacement.functions"> [lib.replacement.functions]</a>, 18.4.1 <a href="lib-support.html#lib.new.delete"> [lib.new.delete]</a>&nbsp; <b>Status:</b>&nbsp;<a href="lwg-active.html#WP">WP</a>&nbsp; <b>Submitter:</b>&nbsp;Matt Austern&nbsp; <b>Date:</b>&nbsp;24 Apr 2003</p>
<p>
The eight basic dynamic memory allocation functions (single-object
and array versions of ::operator new and ::operator delete, in the
ordinary and nothrow forms) are replaceable.  A C++ program may
provide an alternative definition for any of them, which will be used
in preference to the implementation's definition.  
</p>

<p>
Three different parts of the standard mention requirements on
replacement functions: 17.4.3.4 <a href="lib-intro.html#lib.replacement.functions"> [lib.replacement.functions]</a>, 18.4.1.1 <a href="lib-support.html#lib.new.delete.single"> [lib.new.delete.single]</a>
and 18.4.1.2 <a href="lib-support.html#lib.new.delete.array"> [lib.new.delete.array]</a>, and 3.7.3 <a href="basic.html#basic.stc.dynamic"> [basic.stc.dynamic]</a>.
</p>

<p>None of these three places say whether a replacement function may
  be declared inline.  18.4.1.1 <a href="lib-support.html#lib.new.delete.single"> [lib.new.delete.single]</a> paragraph 2 specifies a
  signature for the replacement function, but that's not enough:
  the <tt>inline</tt> specifier is not part of a function's signature.
  One might also reason from 7.1.2 <a href="dcl.html#dcl.fct.spec"> [dcl.fct.spec]</a> paragraph 2, which
  requires that "an inline function shall be defined in every
  translation unit in which it is used," but this may not be quite
  specific enough either.  We should either explicitly allow or
  explicitly forbid inline replacement memory allocation
  functions.</p>
<p><b>Proposed resolution:</b></p>
<p>
Add a new sentence to the end of 17.4.3.4 <a href="lib-intro.html#lib.replacement.functions"> [lib.replacement.functions]</a> paragraph 3:
"The program's definitions shall not be specified as <tt>inline</tt>.
No diagnostic is required."
</p>

<p><i>[Kona: added "no diagnostic is required"]</i></p>

<p><b>Rationale:</b></p>
<p>
The fact that <tt>inline</tt> isn't mentioned appears to have been
nothing more than an oversight.  Existing implementations do not
permit inline functions as replacement memory allocation functions.
Providing this functionality would be difficult in some cases, and is
believed to be of limited value.
</p>
<hr>
<a name="407"><h3>407.&nbsp;Can singular iterators be destroyed?</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#WP">WP</a>&nbsp; <b>Submitter:</b>&nbsp;Nathan Myers&nbsp; <b>Date:</b>&nbsp;3 June 2003</p>
<p>
Clause 24.1 <a href="lib-iterators.html#lib.iterator.requirements"> [lib.iterator.requirements]</a>, paragraph 5, says that the only expression
that is defined for a singular iterator is "an assignment of a
non-singular value to an iterator that holds a singular value".  This 
means that destroying a singular iterator (e.g. letting an automatic
variable go out of scope) is technically undefined behavior.  This
seems overly strict, and probably unintentional.
</p>
<p><b>Proposed resolution:</b></p>
<p>
Change the sentence in question to "... the only exceptions are
destroying an iterator that holds a singular value, or the assignment
of a non-singular value to an iterator that holds a singular value."
</p>
<hr>
<a name="411"><h3>411.&nbsp;Wrong names of set member functions</h3></a><p><b>Section:</b>&nbsp;25.3.5 <a href="lib-algorithms.html#lib.alg.set.operations"> [lib.alg.set.operations]</a>&nbsp; <b>Status:</b>&nbsp;<a href="lwg-active.html#WP">WP</a>&nbsp; <b>Submitter:</b>&nbsp;Daniel Frey&nbsp; <b>Date:</b>&nbsp;9 Jul 2003</p>
<p>
25.3.5 <a href="lib-algorithms.html#lib.alg.set.operations"> [lib.alg.set.operations]</a> paragraph 1 reads:
"The semantics of the set operations are generalized to multisets in a 
standard way by defining union() to contain the maximum number of 
occurrences of every element, intersection() to contain the minimum, and 
so on."
</p>

<p>
This is wrong.  The name of the functions are set_union() and
set_intersection(), not union() and intersection().
</p>
<p><b>Proposed resolution:</b></p>
<p>Change that sentence to use the correct names.</p>
<hr>
<a name="414"><h3>414.&nbsp;Which iterators are invalidated by v.erase()?</h3></a><p><b>Section:</b>&nbsp;23.2.4.3 <a href="lib-containers.html#lib.vector.modifiers"> [lib.vector.modifiers]</a>&nbsp; <b>Status:</b>&nbsp;<a href="lwg-active.html#WP">WP</a>&nbsp; <b>Submitter:</b>&nbsp;Matt Austern&nbsp; <b>Date:</b>&nbsp;19 Aug 2003</p>
<p>
Consider the following code fragment:
</p>
<blockquote>
<pre>
int A[8] = { 1,3,5,7,9,8,4,2 };
std::vector&lt;int&gt; v(A, A+8);

std::vector&lt;int&gt;::iterator i1 = v.begin() + 3;
std::vector&lt;int&gt;::iterator i2 = v.begin() + 4;
v.erase(i1);
</pre>
</blockquote>

<p>
Which iterators are invalidated by <tt>v.erase(i1)</tt>: i1, i2,
both, or neither?
</p>

<p>
On all existing implementations that I know of, the status of i1 and
i2 is the same: both of them will be iterators that point to some
elements of the vector (albeit not the same elements they did
before).  You won't get a crash if you use them.  Depending on 
exactly what you mean by "invalidate", you might say that neither one
has been invalidated because they still point to <i>something</i>,
or you might say that both have been invalidated because in both
cases the elements they point to have been changed out from under the
iterator.
</p>

<p>
The standard doesn't say either of those things.  It says that erase
invalidates all iterators and references "after the point of the
erase".  This doesn't include i1, since it's at the point of the
erase instead of after it.  I can't think of any sensible definition
of invalidation by which one can say that i2 is invalidated but i1
isn't.
</p>

<p>
(This issue is important if you try to reason about iterator validity
based only on the guarantees in the standard, rather than reasoning
from typical implementation techniques.  Strict debugging modes,
which some programmers find useful, do not use typical implementation
techniques.)
</p>
<p><b>Proposed resolution:</b></p>
<p>
In 23.2.4.3 <a href="lib-containers.html#lib.vector.modifiers"> [lib.vector.modifiers]</a> paragraph 3, change "Invalidates all the
iterators and references after the point of the erase" to
"Invalidates iterators and references at or after the point of the
erase". 
</p>
<p><b>Rationale:</b></p>
<p>I believe this was essentially a typographical error, and that it
  was taken for granted that erasing an element invalidates iterators
  that point to it.  The effects clause in question treats iterators
  and references in parallel, and it would seem counterintuitive to
  say that a reference to an erased value remains valid.</p>
<hr>
<a name="420"><h3>420.&nbsp;is std::FILE a complete type?</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#WP">WP</a>&nbsp; <b>Submitter:</b>&nbsp;Martin Sebor&nbsp; <b>Date:</b>&nbsp;18 Sep 2003</p>
<p>
7.19.1, p2, of C99 requires that the FILE type only be declared in
&lt;stdio.h&gt;.  None of the (implementation-defined) members of the
struct is mentioned anywhere for obvious reasons.
</p>

<p>
C++ says in 27.8.1, p2 that FILE is a type that's defined in &lt;cstdio&gt;. Is
it really the intent that FILE be a complete type or is an implementation
allowed to just declare it without providing a full definition?
</p>
<p><b>Proposed resolution:</b></p>
<p>In the first sentence of 27.8.1 <a href="lib-iostreams.html#lib.fstreams"> [lib.fstreams]</a> paragraph 2, change
  "defined" to "declared".</p>
<p><b>Rationale:</b></p>
<p>We don't want to impose any restrictions beyond what the C standard
  already says. We don't want to make anything implementation defined,
  because that imposes new requirements in implementations.</p>
<hr>
<a name="428"><h3>428.&nbsp;string::erase(iterator) validity</h3></a><p><b>Section:</b>&nbsp;21.3.5.5 <a href="lib-strings.html#lib.string::erase"> [lib.string::erase]</a>&nbsp; <b>Status:</b>&nbsp;<a href="lwg-active.html#WP">WP</a>&nbsp; <b>Submitter:</b>&nbsp;Martin Sebor&nbsp; <b>Date:</b>&nbsp;18 Sep 2003</p>
<p>
23.1.1, p3 along with Table 67 specify as a prerequisite for a.erase(q)
that q must be a valid dereferenceable iterator into the sequence a.
</p>

<p>
However, 21.3.5.5, p5 describing string::erase(p) only requires that
p be a valid iterator.
</p>

<p>
This may be interepreted as a relaxation of the general requirement,
which is most likely not the intent.
</p>
<p><b>Proposed resolution:</b></p>
<p>Remove 21.3.5.5 <a href="lib-strings.html#lib.string::erase"> [lib.string::erase]</a> paragraph 5.</p>
<p><b>Rationale:</b></p>
<p>The LWG considered two options: changing the string requirements to
  match the general container requirements, or just removing the
  erroneous string requirements altogether.  The LWG chose the latter
  option, on the grounds that duplicating text always risks the
  possibility that it might be duplicated incorrectly.</p>
<hr>
<a name="436"><h3>436.&nbsp;are cv-qualified facet types valid facets?</h3></a><p><b>Section:</b>&nbsp;22.1.1.1.2 <a href="lib-locales.html#lib.locale.facet"> [lib.locale.facet]</a>&nbsp; <b>Status:</b>&nbsp;<a href="lwg-active.html#WP">WP</a>&nbsp; <b>Submitter:</b>&nbsp;Martin Sebor&nbsp; <b>Date:</b>&nbsp;15 Oct 2003</p>
<p>
Is "const std::ctype&lt;char&gt;" a valid template argument to has_facet, use_facet,
and the locale template ctor? And if so, does it designate the same Facet as
the non-const "std::ctype&lt;char&gt;?" What about "volatile std::ctype&lt;char&gt;?"
Different implementations behave differently: some fail to compile, others
accept such types but behave inconsistently.
</p>
<p><b>Proposed resolution:</b></p>
<p>Change 22.1.1.1.2, p1 to read:</p>

<p>Template parameters in this clause which are required to be facets
are those named Facet in declarations. A program that passes a type
that is not a facet, or a type that refers to volatile-qualified
facet, as an (explicit or deduced) template parameter to a locale
function expecting a facet, is ill-formed.  A const-qualified facet is
a valid template argument to any locale function that expects a Facet
template parameter.</p>

<p><i>[Kona: changed the last sentence from a footnote to normative
text.]</i></p>

<p>----- End of document -----</p>
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