libstdc++-v3/doc/xml/manual/status_cxx2020.xml

   1 <section xmlns="http://docbook.org/ns/docbook" version="5.0"
   2    xml:id="status.iso.2020" xreflabel="Status C++ 2020">
   3 <?dbhtml filename="status_iso_cxx2020.html"?>
   4
   5 <info><title>C++ 2020</title>
   6   <keywordset>
   7     <keyword>ISO C++</keyword>
   8     <keyword>2020</keyword>
   9   </keywordset>
  10 </info>
  11
  12 <para>
  13 In this implementation the <literal>-std=gnu++20</literal> or
  14 <literal>-std=c++20</literal> flag must be used to enable language
  15 and library
  16 features. See <link linkend="manual.intro.using.flags">dialect</link>
  17 options. The pre-defined symbol
  18 <constant>__cplusplus</constant> is used to check for the
  19 presence of the required flag.
  20 </para>
  21
  22 <para>
  23 This section describes the C++20 and library TS support in
  24 mainline GCC, not in any particular release.
  25 </para>
  26
  27 <para>
  28 The following table lists new library features that are included in
  29 the C++20 standard. The "Proposal" column provides a link to the
  30 ISO C++ committee proposal that describes the feature, while the "Status"
  31 column indicates the first version of GCC that contains an implementation of
  32 this feature (if it has been implemented).
  33 A dash (&#x2014;) in the status column indicates that the changes in the proposal
  34 either do not affect the code in libstdc++, or the changes are not required for conformance.
  35 The "SD-6 Feature Test / Notes" column shows the corresponding macro or header from
  36 <link xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="https://isocpp.org/std/standing-documents/sd-6-sg10-feature-test-recommendations">SD-6:
  37 Feature-testing recommendations for C++</link> (where applicable)
  38 or any notes about the implementation.
  39 </para>
  40
  41 <table frame="all" xml:id="table.cxx20_features">
  42 <title>C++ 2020 Library Features</title>
  43
  44 <tgroup cols="4" align="left" colsep="0" rowsep="1">
  45 <colspec colname="c1"/>
  46 <colspec colname="c2"/>
  47 <colspec colname="c3"/>
  48 <colspec colname="c4"/>
  49   <thead>
  50     <row>
  51       <entry>Library Feature</entry>
  52       <entry>Proposal</entry>
  53       <entry>Status</entry>
  54       <entry>SD-6 Feature Test / Notes</entry>
  55     </row>
  56   </thead>
  57
  58   <tbody>
  59
  60     <row>
  61       <entry namest="c1" nameend="c4" align="left">
  62         <emphasis role="bold">Compile-time programming</emphasis>
  63       </entry>
  64     </row>
  65
  66     <row>
  67       <entry>  Add constexpr modifiers to functions in <code>&lt;algorithm&gt;</code> and <code>&lt;utility&gt;</code> Headers </entry>
  68       <entry>
  69         <link xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="https://www.open-std.org/jtc1/sc22/wg21/docs/papers/2017/p0202r3.html">
  70         P0202R3 </link>
  71       </entry>
  72       <entry align="center"> 10.1 </entry>
  73       <entry> <code>__cpp_lib_constexpr_algorithms &gt;= 201703L</code> </entry>
  74     </row>
  75
  76     <row>
  77       <entry>  Constexpr for <code>swap</code> and swap related functions </entry>
  78       <entry>
  79         <link xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="https://www.open-std.org/jtc1/sc22/wg21/docs/papers/2018/p0879r0.html">
  80         P0879R0 </link>
  81       </entry>
  82       <entry align="center"> 10.1 </entry>
  83       <entry> <code>__cpp_lib_constexpr_algorithms &gt;= 201806L</code> </entry>
  84     </row>
  85
  86     <row>
  87       <entry>  Constexpr for <code>std::complex</code> </entry>
  88       <entry>
  89         <link xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="https://www.open-std.org/jtc1/sc22/wg21/docs/papers/2017/p0415r1.html">
  90         P0415R1 </link>
  91       </entry>
  92       <entry align="center"> 9.1 </entry>
  93       <entry> <code>__cpp_lib_constexpr_complex &gt;= 201711L</code> (since 9.4, see Note 1) </entry>
  94     </row>
  95
  96     <row>
  97       <entry>  <code>std::is_constant_evaluated()</code> </entry>
  98       <entry>
  99         <link xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="https://www.open-std.org/jtc1/sc22/wg21/docs/papers/2018/p0595r2.html">
 100         P0595R2 </link>
 101       </entry>
 102       <entry align="center"> 9.1 </entry>
 103       <entry> <code>__cpp_lib_is_constant_evaluated &gt;= 201811L</code> </entry>
 104     </row>
 105
 106     <row>
 107       <entry>  More constexpr containers </entry>
 108       <entry>
 109         <link xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="https://www.open-std.org/jtc1/sc22/wg21/docs/papers/2019/p0784r7.html">
 110         P0784R7 </link>
 111       </entry>
 112       <entry align="center"> 10.1 </entry>
 113       <entry> <code>__cpp_lib_constexpr_dynamic_alloc &gt;= 201907L</code> </entry>
 114     </row>
 115
 116     <row>
 117       <entry>  Making <code>std::string</code> constexpr </entry>
 118       <entry>
 119         <link xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="https://www.open-std.org/jtc1/sc22/wg21/docs/papers/2019/p0980r1.pdf">
 120         P0980R1 </link>
 121       </entry>
 122       <entry align="center"> 12.1 </entry>
 123       <entry> <code>__cpp_lib_constexpr_string &gt;= 201907L</code> </entry>
 124     </row>
 125
 126     <row>
 127       <entry>  Making <code>std::vector</code> constexpr </entry>
 128       <entry>
 129         <link xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="https://www.open-std.org/jtc1/sc22/wg21/docs/papers/2019/p1004r2.pdf">
 130         P1004R2 </link>
 131       </entry>
 132       <entry align="center"> 12.1 </entry>
 133       <entry> <code>__cpp_lib_constexpr_vector &gt;= 201907L</code> </entry>
 134     </row>
 135
 136     <row>
 137       <entry>  Constexpr in <code>std::pointer_traits</code> </entry>
 138       <entry>
 139         <link xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="https://www.open-std.org/jtc1/sc22/wg21/docs/papers/2018/p1006r1.pdf">
 140         P1006R1 </link>
 141       </entry>
 142       <entry align="center"> 9.1 </entry>
 143       <entry> <code>__cpp_lib_constexpr_memory &gt;= 201811L</code> (since 9.4, see Note 1) </entry>
 144     </row>
 145
 146     <row>
 147       <entry>  constexpr for <code>&lt;numeric&gt;</code> algorithms </entry>
 148       <entry>
 149         <link xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="https://www.open-std.org/jtc1/sc22/wg21/docs/papers/2019/p1645r1.html">
 150         P1645R1 </link>
 151       </entry>
 152       <entry align="center"> 10.1 </entry>
 153       <entry> <code>__cpp_lib_constexpr_numeric &gt;= 201911L</code> </entry>
 154     </row>
 155
 156     <row>
 157       <entry>  Constexpr iterator requirements </entry>
 158       <entry>
 159         <link xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="https://www.open-std.org/jtc1/sc22/wg21/docs/papers/2018/p0858r0.html">
 160         P0858R0 </link>
 161       </entry>
 162       <entry align="center"> 9.1 </entry>
 163       <entry>
 164         <informaltable colsep="0" rowsep="0" rowheader="norowheader" frame="none"><tgroup cols="1"><tbody>
 165         <row><entry> <code>__cpp_lib_array_constexpr &gt;= 201803L</code> </entry></row>
 166         <row><entry> <code>__cpp_lib_string_view &gt;= 201803L</code> </entry></row>
 167         <row><entry> (both since 9.4, see Note 1) </entry></row>
 168         </tbody></tgroup></informaltable>
 169       </entry>
 170     </row>
 171
 172     <row>
 173       <entry>  <code>constexpr</code> comparison operators for <code>std::array</code> </entry>
 174       <entry>
 175         <link xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="https://www.open-std.org/jtc1/sc22/wg21/docs/papers/2018/p1023r0.pdf">
 176         P1023R0 </link>
 177       </entry>
 178       <entry align="center"> 10.1 </entry>
 179       <entry> <code>__cpp_lib_array_constexpr &gt;= 201806</code> </entry>
 180     </row>
 181
 182     <row>
 183       <entry>  Misc constexpr bits </entry>
 184       <entry>
 185         <link xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="https://www.open-std.org/jtc1/sc22/wg21/docs/papers/2018/p1032r1.html">
 186         P1032R1 </link>
 187       </entry>
 188       <entry align="center"> 10.1 </entry>
 189       <entry>
 190         <informaltable colsep="0" rowsep="0" rowheader="norowheader" frame="none"><tgroup cols="1"><tbody>
 191         <row><entry> <code>__cpp_lib_array_constexpr &gt;= 201811L</code> </entry></row>
 192         <row><entry> <code>__cpp_lib_constexpr_functional &gt;= 201811L</code> </entry></row>
 193         <row><entry> <code>__cpp_lib_constexpr_iterator &gt;= 201811L</code> </entry></row>
 194         <row><entry> <code>__cpp_lib_constexpr_string_view &gt;= 201811L</code> </entry></row>
 195         <row><entry> <code>__cpp_lib_constexpr_tuple &gt;= 201811L</code> </entry></row>
 196         <row><entry> <code>__cpp_lib_constexpr_utility &gt;= 201811L</code> </entry></row>
 197         </tbody></tgroup></informaltable>
 198       </entry>
 199     </row>
 200
 201     <row>
 202       <entry>  <code>constexpr <emphasis>INVOKE</emphasis></code> </entry>
 203       <entry>
 204         <link xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="https://www.open-std.org/jtc1/sc22/wg21/docs/papers/2019/p1065r2.html">
 205         P1065R2 </link>
 206       </entry>
 207       <entry align="center"> 10.1 </entry>
 208       <entry> <code>__cpp_lib_constexpr_functional &gt;= 201907L</code> </entry>
 209     </row>
 210
 211
 212     <row>
 213       <entry>  Transformation Trait <code>remove_cvref</code> </entry>
 214       <entry>
 215         <link xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="https://www.open-std.org/jtc1/sc22/wg21/docs/papers/2017/p0550r2.pdf">
 216         P0550R2 </link>
 217       </entry>
 218       <entry align="center"> 9.1 </entry>
 219       <entry> <code>__cpp_lib_remove_cvref &gt;= 201711L</code> (since 9.4, see Note 1) </entry>
 220     </row>
 221
 222     <row>
 223       <entry>  Implicit conversion traits and utility functions </entry>
 224       <entry>
 225         <link xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="https://www.open-std.org/jtc1/sc22/wg21/docs/papers/2018/p0758r1.html">
 226         P0758R1 </link>
 227       </entry>
 228       <entry align="center"> 9.1 </entry>
 229       <entry> <code>__cpp_lib_is_nothrow_convertible &gt;= 201806L</code>  (since 9.4, see Note 1) </entry>
 230     </row>
 231
 232     <row>
 233       <entry>  The <code>identity</code> metafunction </entry>
 234       <entry>
 235         <link xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="https://www.open-std.org/jtc1/sc22/wg21/docs/papers/2018/p0887r1.pdf">
 236         P0887R1 </link>
 237       </entry>
 238       <entry align="center"> 9.1 </entry>
 239       <entry> <code>__cpp_lib_type_identity &gt;= 201806L</code> (since 9.4, see Note 1) </entry>
 240     </row>
 241
 242
 243     <row>
 244       <entry>  <code>unwrap_ref_decay</code> and <code>unwrap_reference</code> </entry>
 245       <entry>
 246         <link xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="https://www.open-std.org/jtc1/sc22/wg21/docs/papers/2018/p0318r1.pdf">
 247         P0318R1 </link>
 248       </entry>
 249       <entry align="center"> 9.1 </entry>
 250       <entry> <code>__cpp_lib_unwrap_ref &gt;= 201811L</code> (since 9.4, see Note 1) </entry>
 251     </row>
 252
 253     <row>
 254       <entry>  Improving Completeness Requirements for Type Traits </entry>
 255       <entry>
 256         <link xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="https://www.open-std.org/jtc1/sc22/wg21/docs/papers/2018/p1285r0.pdf">
 257         P1285R0 </link>
 258       </entry>
 259       <entry align="center"> &#x2014; </entry>
 260       <entry> Most misuses are diagnosed, but not all. </entry>
 261     </row>
 262
 263     <row>
 264       <entry>  Missing feature test macros </entry>
 265       <entry>
 266         <link xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="https://www.open-std.org/jtc1/sc22/wg21/docs/papers/2018/p1353r0.html">
 267         P1353R0 </link>
 268       </entry>
 269       <entry align="center"> 9.1 </entry>
 270       <entry />
 271     </row>
 272
 273     <row>
 274       <entry> Making std::underlying_type SFINAE-friendly </entry>
 275       <entry>
 276         <link xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="https://www.open-std.org/jtc1/sc22/wg21/docs/papers/2019/p0340r3.html">
 277         P0340R3 </link>
 278       </entry>
 279       <entry align="center"> 9.1 </entry>
 280       <entry />
 281     </row>
 282
 283     <row>
 284       <entry> Traits for [Un]bounded Arrays </entry>
 285       <entry>
 286         <link xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="https://www.open-std.org/jtc1/sc22/wg21/docs/papers/2019/p1357r1.pdf">
 287         P1357R1 </link>
 288       </entry>
 289       <entry align="center"> 9.1 </entry>
 290       <entry> <code>__cpp_lib_bounded_array_traits &gt;= 201902L</code> </entry>
 291     </row>
 292
 293     <row>
 294       <entry> Layout-compatibility and pointer-interconvertibility traits </entry>
 295       <entry>
 296         <link xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="https://www.open-std.org/jtc1/sc22/wg21/docs/papers/2019/p0466r5.pdf">
 297         P0466R5 </link>
 298       </entry>
 299       <entry align="center"> 12.1 </entry>
 300       <entry>
 301         <informaltable colsep="0" rowsep="0" rowheader="norowheader" frame="none"><tgroup cols="1"><tbody>
 302         <row><entry> <code>__cpp_lib_is_layout_compatible &gt;= 201907L</code> </entry></row>
 303         <row><entry> <code>__cpp_lib_is_pointer_interconvertible &gt;= 201907L</code> </entry></row>
 304         </tbody></tgroup></informaltable>
 305       </entry>
 306     </row>
 307
 308     <row>
 309       <entry>  Integrating feature-test macros into the C++ WD </entry>
 310       <entry>
 311         <link xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="https://www.open-std.org/jtc1/sc22/wg21/docs/papers/2018/p0941r2.html">
 312         P0941R2 </link>
 313       </entry>
 314       <entry align="center"> 5.1 </entry>
 315       <entry />
 316     </row>
 317
 318     <row>
 319       <entry>  <code>&lt;version&gt;</code> </entry>
 320       <entry>
 321         <link xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="https://www.open-std.org/jtc1/sc22/wg21/docs/papers/2018/p0754r2.pdf">
 322         P0754R2 </link>
 323       </entry>
 324       <entry align="center"> 9.1 </entry>
 325       <entry> <code>__has_include(&lt;version&gt;)</code> </entry>
 326     </row>
 327
 328
 329     <row>
 330       <entry namest="c1" nameend="c4" align="left">
 331         <emphasis role="bold">Synchronization</emphasis>
 332       </entry>
 333     </row>
 334
 335     <row>
 336       <entry>  Atomic Ref </entry>
 337       <entry>
 338         <link xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="https://www.open-std.org/jtc1/sc22/wg21/docs/papers/2018/p0019r8.html">
 339         P0019R8 </link>
 340       </entry>
 341       <entry align="center"> 10.1 </entry>
 342       <entry> <code>__cpp_lib_atomic_ref &gt;= 201806L</code> </entry>
 343     </row>
 344
 345     <row>
 346       <entry>  Floating Point Atomic </entry>
 347       <entry>
 348         <link xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="https://www.open-std.org/jtc1/sc22/wg21/docs/papers/2017/p0020r6.html">
 349         P0020R6 </link>
 350       </entry>
 351       <entry align="center"> 10.1 </entry>
 352       <entry> <code>__cpp_lib_atomic_float &gt;= 201711L</code> </entry>
 353     </row>
 354
 355     <row>
 356       <entry>  C++ Synchronized Buffered Ostream </entry>
 357       <entry>
 358         <link xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="https://www.open-std.org/jtc1/sc22/wg21/docs/papers/2017/p0053r7.pdf">
 359         P0053R7 </link>
 360       </entry>
 361       <entry align="center"> 11.1 </entry>
 362       <entry> <code>__cpp_lib_syncbuf &gt;= 201711L</code> </entry>
 363     </row>
 364
 365     <row>
 366       <entry>  Manipulators for C++ Synchronized Buffered Ostream </entry>
 367       <entry>
 368         <link xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="https://www.open-std.org/jtc1/sc22/wg21/docs/papers/2018/p0753r2.pdf">
 369         P0753R2 </link>
 370       </entry>
 371       <entry align="center"> 11.1 </entry>
 372       <entry> <code>__cpp_lib_syncbuf &gt;= 201803L</code> </entry>
 373     </row>
 374
 375     <row>
 376       <entry>  Make <code>std::memory_order</code> a scoped enumeration </entry>
 377       <entry>
 378         <link xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="https://www.open-std.org/jtc1/sc22/wg21/docs/papers/2016/p0439r0.html">
 379         P0439R0 </link>
 380       </entry>
 381       <entry align="center"> 9.1 </entry>
 382       <entry />
 383     </row>
 384
 385     <row>
 386       <entry>  The Curious Case of Padding Bits, Featuring Atomic Compare-and-Exchange </entry>
 387       <entry>
 388         <link xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="https://www.open-std.org/jtc1/sc22/wg21/docs/papers/2018/p0528r3.html">
 389         P0528R3 </link>
 390       </entry>
 391       <entry align="center"> 13.1 </entry>
 392       <entry />
 393     </row>
 394
 395     <row>
 396       <entry>  Atomic <code>shared_ptr</code> </entry>
 397       <entry>
 398         <link xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="https://www.open-std.org/jtc1/sc22/wg21/docs/papers/2017/p0718r2.html">
 399         P0718R2 </link>
 400       </entry>
 401       <entry align="center"> 12.1 </entry>
 402       <entry> <code> __cpp_lib_atomic_shared_ptr &gt;= 201711L</code> </entry>
 403     </row>
 404
 405     <row>
 406       <entry> std::stop_token and std::jthread </entry>
 407       <entry>
 408         <link xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="https://www.open-std.org/jtc1/sc22/wg21/docs/papers/2019/p0660r10.pdf">
 409         P0660R10 </link>
 410       </entry>
 411       <entry align="center"> 10.1 </entry>
 412       <entry> <code>__cpp_lib_jthread &gt;= 201907L</code> </entry>
 413     </row>
 414
 415     <row>
 416       <entry> Rename <code>condition_variable_any</code> interruptible wait methods </entry>
 417       <entry>
 418         <link xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="https://www.open-std.org/jtc1/sc22/wg21/docs/papers/2019/p1869r1.html">
 419         P1869R1 </link>
 420       </entry>
 421       <entry align="center"> 10.1 </entry>
 422       <entry> <code>__cpp_lib_jthread &gt;= 201911L</code> </entry>
 423     </row>
 424
 425     <row>
 426       <entry> Atomic waiting and notifying, std::semaphore, std::latch and std::barrier </entry>
 427       <entry>
 428         <link xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="https://www.open-std.org/jtc1/sc22/wg21/docs/papers/2019/p1135r6.html">
 429         P1135R6 </link>
 430       </entry>
 431       <entry align="center"> 11.1 </entry>
 432       <entry>
 433         <informaltable colsep="0" rowsep="0" rowheader="norowheader" frame="none"><tgroup cols="1"><tbody>
 434         <row><entry> <code>__cpp_lib_atomic_lock_free_type_aliases &gt;= 201907L</code> </entry></row>
 435         <row><entry> <code>__cpp_lib_atomic_flag_test &gt;= 201907L</code> </entry></row>
 436         <row><entry> <code>__cpp_lib_atomic_wait &gt;= 201907L</code> </entry></row>
 437         <row><entry> <code>__cpp_lib_semaphore &gt;= 201907L</code> </entry></row>
 438         <row><entry> <code>__cpp_lib_latch &gt;= 201907L</code> </entry></row>
 439         <row><entry> <code>__cpp_lib_barrier &gt;= 201907L</code> </entry></row>
 440         </tbody></tgroup></informaltable>
 441       </entry>
 442     </row>
 443
 444     <row>
 445       <entry> Fixing Atomic Initialization </entry>
 446       <entry>
 447         <link xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="https://www.open-std.org/jtc1/sc22/wg21/docs/papers/2019/p0883r2.pdf">
 448         P0883R2 </link>
 449       </entry>
 450       <entry align="center"> 10.1 </entry>
 451       <entry> <code>__cpp_lib_atomic_value_initialization &gt;= 201911L</code> </entry>
 452     </row>
 453
 454
 455
 456     <row>
 457       <entry namest="c1" nameend="c4" align="left">
 458         <emphasis role="bold">Ranges and Concepts</emphasis>
 459       </entry>
 460     </row>
 461
 462     <row>
 463       <entry>  Standard Library Concepts </entry>
 464       <entry>
 465         <link xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="https://www.open-std.org/jtc1/sc22/wg21/docs/papers/2018/p0898r3.pdf">
 466         P0898R3 </link>
 467       </entry>
 468       <entry align="center"> 10.1 </entry>
 469       <entry> <code>__cpp_lib_concepts &gt;= 201806L</code> </entry>
 470     </row>
 471
 472     <row>
 473       <entry>  Rename concepts to standard_case for C++20, while we still can </entry>
 474       <entry>
 475         <link xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="https://www.open-std.org/jtc1/sc22/wg21/docs/papers/2019/p1754r1.pdf">
 476         P1754R1 </link>
 477       </entry>
 478       <entry align="center"> 10.1 </entry>
 479       <entry> <code>__cpp_lib_concepts &gt;= 201907L</code> </entry>
 480     </row>
 481
 482     <row>
 483       <entry>  Wording for <emphasis><code>boolean-testable</code></emphasis> </entry>
 484       <entry>
 485         <link xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="https://www.open-std.org/jtc1/sc22/wg21/docs/papers/2020/p1964r2.html">
 486         P1964R2 </link>
 487       </entry>
 488       <entry align="center"> 10.1 </entry>
 489       <entry> <code>__cpp_lib_concepts &gt;= 202002L</code> </entry>
 490     </row>
 491
 492     <row>
 493       <entry>  The One Ranges Proposal </entry>
 494       <entry>
 495         <link xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="https://www.open-std.org/jtc1/sc22/wg21/docs/papers/2018/p0896r4.pdf">
 496         P0896R4 </link>
 497       </entry>
 498       <entry align="center"> 10.1 </entry>
 499       <entry> <code>__cpp_lib_ranges &gt;= 201811L</code> </entry>
 500     </row>
 501
 502     <row>
 503       <entry>  Input Range Adaptors </entry>
 504       <entry>
 505         <link xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="https://www.open-std.org/jtc1/sc22/wg21/docs/papers/2019/p1035r7.pdf">
 506         P1035R7 </link>
 507       </entry>
 508       <entry align="center"> 10.1 </entry>
 509       <entry> <code>__cpp_lib_ranges &gt;= 201907L</code> </entry>
 510     </row>
 511
 512     <row>
 513       <entry>  <code>ranges</code> compare algorithm are over-constrained </entry>
 514       <entry>
 515         <link xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="https://www.open-std.org/jtc1/sc22/wg21/docs/papers/2019/p1716r3.html">
 516         P1716R3 </link>
 517       </entry>
 518       <entry align="center"> 10.1 </entry>
 519       <entry> <code>__cpp_lib_ranges &gt;= 201911L</code> </entry>
 520     </row>
 521
 522     <row>
 523       <entry>  Remove CommonReference requirement from StrictWeakOrdering (a.k.a Fixing Relations) </entry>
 524       <entry>
 525         <link xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="https://www.open-std.org/jtc1/sc22/wg21/docs/papers/2018/p1248r1.html">
 526         P1248R1 </link>
 527       </entry>
 528       <entry align="center"> 10.1 </entry>
 529       <entry />
 530     </row>
 531
 532     <row>
 533       <entry> Ranges Design Cleanup </entry>
 534       <entry>
 535         <link xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="https://www.open-std.org/jtc1/sc22/wg21/docs/papers/2019/p1252r2.pdf">
 536         P1252R2 </link>
 537       </entry>
 538       <entry align="center"> 10.1 </entry>
 539       <entry />
 540     </row>
 541
 542     <row>
 543       <entry> Avoid template bloat for <code>safe_ranges</code> in combination with ‘subrange-y’ view adaptors.</entry>
 544       <entry>
 545         <link xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="https://www.open-std.org/jtc1/sc22/wg21/docs/papers/2020/p1739r4.html">
 546         P1739R4 </link>
 547       </entry>
 548       <entry align="center"> 12.1 </entry>
 549       <entry />
 550     </row>
 551
 552
 553     <row>
 554       <entry namest="c1" nameend="c4" align="left">
 555         <emphasis role="bold">Time, dates, calendars, time zones</emphasis>
 556       </entry>
 557     </row>
 558
 559     <row>
 560       <entry>  Extending chrono to Calendars and Time Zones </entry>
 561       <entry>
 562         <link xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="https://www.open-std.org/jtc1/sc22/wg21/docs/papers/2018/p0355r7.html">
 563         P0355R7 </link>
 564       </entry>
 565       <entry> 14.1 (see Note 2) </entry>
 566       <entry> <code>__cpp_lib_chrono &gt;= 201803L</code> </entry>
 567     </row>
 568
 569     <row>
 570       <entry> Miscellaneous minor fixes for chrono </entry>
 571       <entry>
 572         <link xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="https://www.open-std.org/jtc1/sc22/wg21/docs/papers/2019/p1466r3.html">
 573         P1466R3 </link>
 574       </entry>
 575       <entry> 11.1 (see Note 2) </entry>
 576       <entry> <code>__cpp_lib_chrono &gt;= 201907L</code> </entry>
 577     </row>
 578
 579     <row>
 580       <entry>  <code>&lt;chrono&gt;</code> <code>zero()</code>, <code>min()</code>, and <code>max()</code> should be <code>noexcept</code> </entry>
 581       <entry>
 582         <link xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="https://www.open-std.org/jtc1/sc22/wg21/docs/papers/2018/p0972r0.pdf">
 583         P0972R0 </link>
 584       </entry>
 585       <entry align="center"> 9.1 </entry>
 586       <entry />
 587     </row>
 588
 589
 590     <row>
 591       <entry namest="c1" nameend="c4" align="left">
 592         <emphasis role="bold">Three-way comparison</emphasis>
 593       </entry>
 594     </row>
 595
 596     <row>
 597       <entry>  Library Support for the Spaceship (Comparison) Operator </entry>
 598       <entry>
 599         <link xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="https://www.open-std.org/jtc1/sc22/wg21/docs/papers/2017/p0768r1.pdf">
 600         P0768R1 </link>
 601       </entry>
 602       <entry align="center"> 10.1 </entry>
 603       <entry> <code>__cpp_lib_three_way_comparison &gt;= 201711L</code> </entry>
 604     </row>
 605
 606     <row>
 607       <entry>  Symmetry for spaceship </entry>
 608       <entry>
 609         <link xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="https://www.open-std.org/jtc1/sc22/wg21/docs/papers/2018/p0905r1.html">
 610         P0905R1 </link>
 611       </entry>
 612       <entry align="center"> 10.1 </entry>
 613       <entry />
 614     </row>
 615
 616     <row>
 617       <entry> Adding &lt;=&gt; to the standard library </entry>
 618       <entry>
 619         <link xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="https://www.open-std.org/jtc1/sc22/wg21/docs/papers/2019/p1614r2.html">
 620         P1614R2 </link>
 621       </entry>
 622       <entry align="center"> 10.1 </entry>
 623       <entry>
 624         <code>__cpp_lib_three_way_comparison &gt;= 201907L</code>
 625       </entry>
 626     </row>
 627
 628
 629     <row>
 630       <entry namest="c1" nameend="c4" align="left">
 631         <emphasis role="bold">Strings and text</emphasis>
 632       </entry>
 633     </row>
 634
 635     <row>
 636       <entry>  <code>string::reserve</code> Should Not Shrink </entry>
 637       <entry>
 638         <link xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="https://www.open-std.org/jtc1/sc22/wg21/docs/papers/2018/p0966r1.html">
 639         P0966R1 </link>
 640       </entry>
 641       <entry align="center"> 11.1 </entry>
 642       <entry />
 643     </row>
 644
 645     <row>
 646       <entry>  <code>char8_t</code>: A type for UTF-8 characters and strings </entry>
 647       <entry>
 648         <link xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="https://www.open-std.org/jtc1/sc22/wg21/docs/papers/2018/p0482r6.html">
 649         P0482R6 </link>
 650       </entry>
 651       <entry align="center"> 9.1 </entry>
 652       <entry> <code>__cpp_lib_char8_t &gt;= 201811L</code> </entry>
 653     </row>
 654
 655     <row>
 656       <entry>  <code>char8_t</code> backward compatibility remediation </entry>
 657       <entry>
 658         <link xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="https://www.open-std.org/jtc1/sc22/wg21/docs/papers/2019/p1423r3.html">
 659         P1423R3 </link>
 660       </entry>
 661       <entry align="center"> 10.1 </entry>
 662       <entry> <code>__cpp_lib_char8_t &gt;= 201907L</code> </entry>
 663     </row>
 664
 665     <row>
 666       <entry> Text formatting </entry>
 667       <entry>
 668         <link xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="https://www.open-std.org/jtc1/sc22/wg21/docs/papers/2019/p0645r10.html">
 669         P0645R10 </link>
 670       </entry>
 671       <entry align="center"> 13.1 </entry>
 672       <entry>
 673         <code>__cpp_lib_format &gt;= 201907L</code>
 674       </entry>
 675     </row>
 676
 677     <row>
 678       <entry> Integration of chrono with text formatting </entry>
 679       <entry>
 680         <link xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="https://www.open-std.org/jtc1/sc22/wg21/docs/papers/2019/p1361r2.pdf">
 681         P1361R2 </link>
 682       </entry>
 683       <entry align="center"> 13.1 </entry>
 684       <entry>
 685         <code>__cpp_lib_format &gt;= 201907L</code>
 686       </entry>
 687     </row>
 688
 689     <row>
 690       <entry> Printf corner cases in <code>std::format</code> </entry>
 691       <entry>
 692         <link xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="https://www.open-std.org/jtc1/sc22/wg21/docs/papers/2019/p1652r1.html">
 693         P1652R1 </link>
 694       </entry>
 695       <entry align="center"> 13.1 </entry>
 696       <entry>
 697         <code>__cpp_lib_format &gt;= 201907L</code>
 698       </entry>
 699     </row>
 700
 701     <row>
 702       <entry>  String Prefix and Suffix Checking </entry>
 703       <entry>
 704         <link xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="https://www.open-std.org/jtc1/sc22/wg21/docs/papers/2017/p0457r2.html">
 705         P0457R2 </link>
 706       </entry>
 707       <entry align="center"> 9.1 </entry>
 708       <entry> <code>__cpp_lib_starts_ends_with &gt;= 201711L</code> (since 9.4, see Note 1) </entry>
 709     </row>
 710
 711     <row>
 712       <entry>  Update The Reference To The Unicode Standard </entry>
 713       <entry>
 714         <link xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="https://www.open-std.org/jtc1/sc22/wg21/docs/papers/2018/p1025r1.html">
 715         P1025R1 </link>
 716       </entry>
 717       <entry align="center"> &#x2014;</entry>
 718       <entry />
 719     </row>
 720
 721
 722     <row>
 723       <entry namest="c1" nameend="c4" align="left">
 724         <emphasis role="bold">Containers</emphasis>
 725       </entry>
 726     </row>
 727
 728     <row>
 729       <entry> span: bounds-safe views for sequences of objects </entry>
 730       <entry>
 731         <link xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="https://www.open-std.org/jtc1/sc22/wg21/docs/papers/2018/p0122r7.pdf">
 732         P0122R7 </link>
 733       </entry>
 734       <entry align="center"> 10.1 </entry>
 735       <entry> <code>__cpp_lib_span &gt;= 201803L</code> </entry>
 736     </row>
 737
 738     <row>
 739       <entry>
 740         Usability Enhancements for <classname>std::span</classname>
 741       </entry>
 742       <entry>
 743         <link xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="https://www.open-std.org/jtc1/sc22/wg21/docs/papers/2019/p1024r3.pdf">
 744         P1024R3 </link>
 745       </entry>
 746       <entry align="center"> 10.1 </entry>
 747       <entry> <code>__cpp_lib_span &gt;= 201902L</code> </entry>
 748     </row>
 749
 750     <row>
 751       <entry>  Should Span be Regular? </entry>
 752       <entry>
 753         <link xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="https://www.open-std.org/jtc1/sc22/wg21/docs/papers/2018/p1085r2.md">
 754         P1085R2 </link>
 755       </entry>
 756       <entry align="center"> 10.1 </entry>
 757       <entry/>
 758     </row>
 759
 760     <row>
 761       <entry> Fixed-size <code>&lt;span&gt;</code> construction from dynamic range </entry>
 762       <entry>
 763         <link xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="https://www.open-std.org/jtc1/sc22/wg21/docs/papers/2020/p1976r2.html">
 764         P1976R2 </link>
 765       </entry>
 766       <entry align="center"> 10.1 </entry>
 767       <entry> <code>__cpp_lib_span &gt;= 202002L</code> </entry>
 768     </row>
 769
 770     <row>
 771       <entry> <code>std::to_array</code> </entry>
 772       <entry>
 773         <link xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="https://www.open-std.org/jtc1/sc22/wg21/docs/papers/2019/p0325r4.html">
 774         P0325R4 </link>
 775       </entry>
 776       <entry align="center"> 10.1 </entry>
 777       <entry> <code>__cpp_lib_to_array &gt;= 201907L</code> </entry>
 778     </row>
 779
 780     <row>
 781       <entry>  Checking for Existence of an Element in Associative Containers </entry>
 782       <entry>
 783         <link xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="https://www.open-std.org/jtc1/sc22/wg21/docs/papers/2018/p0458r2.html">
 784         P0458R2 </link>
 785       </entry>
 786       <entry align="center"> 9.1 </entry>
 787       <entry />
 788     </row>
 789
 790     <row>
 791       <entry>  Comparing Unordered Containers </entry>
 792       <entry>
 793         <link xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="https://www.open-std.org/jtc1/sc22/wg21/docs/papers/2018/p0809r0.pdf">
 794         P0809R0 </link>
 795       </entry>
 796       <entry align="center"> &#x2014; </entry>
 797       <entry />
 798     </row>
 799
 800     <row>
 801       <entry>  Heterogeneous lookup for unordered containers </entry>
 802       <entry>
 803         <link xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="https://www.open-std.org/jtc1/sc22/wg21/docs/papers/2018/p0919r3.html">
 804         P0919R3 </link>
 805       </entry>
 806       <entry align="center"> 11.1 </entry>
 807       <entry> <code>__cpp_lib_generic_unordered_lookup &gt;= 201811</code> </entry>
 808     </row>
 809
 810     <row>
 811       <entry> Refinement Proposal for P0919 </entry>
 812       <entry>
 813         <link xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="https://www.open-std.org/jtc1/sc22/wg21/docs/papers/2019/p1690r1.html">
 814         P1690R1 </link>
 815       </entry>
 816       <entry align="center"> 11.1 </entry>
 817       <entry/>
 818     </row>
 819
 820     <row>
 821       <entry>  Adopt Consistent Container Erasure from Library Fundamentals 2 for C++20 </entry>
 822       <entry>
 823         <link xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="https://www.open-std.org/jtc1/sc22/wg21/docs/papers/2018/p1209r0.html">
 824         P1209R0 </link>
 825       </entry>
 826       <entry align="center"> 9.1 </entry>
 827       <entry> <code>__cpp_lib_erase_if &gt;= 201811L</code> </entry>
 828     </row>
 829
 830     <row>
 831       <entry>  Improving the Return Value of Erase-Like Algorithms </entry>
 832       <entry>
 833         <link xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="https://www.open-std.org/jtc1/sc22/wg21/docs/papers/2018/p0646r1.pdf">
 834         P0646R1 </link>
 835       </entry>
 836       <entry align="center"> 9.1 </entry>
 837       <entry> <code>__cpp_lib_list_remove_return_type &gt;= 201806L</code> </entry>
 838     </row>
 839
 840     <row>
 841       <entry>  Improving the Return Value of Erase-Like Algorithms II: Free <code>erase</code>/<code>erase_if</code> </entry>
 842       <entry>
 843         <link xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="https://www.open-std.org/jtc1/sc22/wg21/docs/papers/2019/p1115r3.pdf">
 844         P1115R3 </link>
 845       </entry>
 846       <entry align="center"> 9.1 </entry>
 847       <entry>
 848         <informaltable colsep="0" rowsep="0" rowheader="norowheader" frame="none"><tgroup cols="1"><tbody>
 849         <row><entry> <code>__cpp_lib_erase_if &gt;= 202002L</code> </entry></row>
 850         <row><entry> (defined to <code>201900L</code> for GCC 9.1 and 9.2 so use <code>&gt; 201811L</code>) </entry></row>
 851         </tbody></tgroup></informaltable>
 852       </entry>
 853     </row>
 854
 855     <row>
 856       <entry> Signed ssize() functions, unsigned size() functions </entry>
 857       <entry>
 858         <link xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="https://www.open-std.org/jtc1/sc22/wg21/docs/papers/2019/p1227r2.html">
 859         P1227R2 </link>
 860       </entry>
 861       <entry align="center"> 10.1 </entry>
 862       <entry> <code>__cpp_lib_ssize &gt;= 201902L</code> </entry>
 863     </row>
 864
 865
 866     <row>
 867       <entry namest="c1" nameend="c4" align="left">
 868         <emphasis role="bold">Memory management</emphasis>
 869       </entry>
 870     </row>
 871
 872     <row>
 873       <entry>  Utility to convert a pointer to a raw pointer </entry>
 874       <entry>
 875         <link xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="https://www.open-std.org/jtc1/sc22/wg21/docs/papers/2017/p0653r2.html">
 876         P0653R2 </link>
 877       </entry>
 878       <entry align="center"> 8.1 </entry>
 879       <entry> <code>__cpp_lib_to_address &gt;= 201711L</code> (since 9.4, see Note 1) </entry>
 880     </row>
 881
 882     <row>
 883       <entry>  Extending <code>make_shared</code> to Support Arrays </entry>
 884       <entry>
 885         <link xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="https://www.open-std.org/jtc1/sc22/wg21/docs/papers/2017/p0674r1.html">
 886         P0674R1 </link>
 887       </entry>
 888       <entry align="center"> 12.1 </entry>
 889       <entry> <code>__cpp_lib_shared_ptr_arrays &gt;= 201707L</code> </entry>
 890     </row>
 891
 892     <row>
 893       <entry>  Efficient sized delete for variable sized classes </entry>
 894       <entry>
 895         <link xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="https://www.open-std.org/jtc1/sc22/wg21/docs/papers/2018/p0722r3.html">
 896         P0722R3 </link>
 897       </entry>
 898       <entry align="center"> 9.1 </entry>
 899       <entry> <code>__cpp_lib_destroying_delete &gt;= 201806L</code> </entry>
 900     </row>
 901
 902     <row>
 903       <entry>  Utility functions to implement uses-allocator construction </entry>
 904       <entry>
 905         <link xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="https://www.open-std.org/jtc1/sc22/wg21/docs/papers/2018/p0591r4.pdf">
 906         P0591R4 </link>
 907       </entry>
 908       <entry align="center"> 9.1 </entry>
 909       <entry>
 910         <code>std::scoped_allocator_adaptor</code> changes missing in 9.1.0
 911       </entry>
 912     </row>
 913
 914     <row>
 915       <entry>  <code>std::assume_aligned</code> </entry>
 916       <entry>
 917         <link xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="https://www.open-std.org/jtc1/sc22/wg21/docs/papers/2018/p1007r3.pdf">
 918         P1007R3 </link>
 919       </entry>
 920       <entry align="center"> 9.1 </entry>
 921       <entry> <code>__cpp_lib_assume_aligned &gt;= 201811L</code> (since 9.4, see Note 1) </entry>
 922     </row>
 923
 924     <row>
 925       <entry>  Smart pointer creation with default initialization </entry>
 926       <entry>
 927         <link xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="https://www.open-std.org/jtc1/sc22/wg21/docs/papers/2018/p1020r1.html">
 928         P1020R1 </link>
 929       </entry>
 930       <entry align="center"> 12.1 </entry>
 931       <entry> <code>__cpp_lib_smart_ptr_for_overwrite &gt;= 201811L</code> </entry>
 932     </row>
 933
 934     <row>
 935       <entry>  Rename "default_init" Functions </entry>
 936       <entry>
 937         <link xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="https://www.open-std.org/jtc1/sc22/wg21/docs/papers/2020/p1973r1.pdf">
 938         P1973R1 </link>
 939       </entry>
 940       <entry align="center"> 12.1 </entry>
 941       <entry> <code>__cpp_lib_smart_ptr_for_overwrite &gt;= 201811L</code> </entry>
 942     </row>
 943
 944     <row>
 945       <entry>  Make stateful allocator propagation more consistent for <code>operator+(basic_string)</code> </entry>
 946       <entry>
 947         <link xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="https://www.open-std.org/jtc1/sc22/wg21/docs/papers/2018/p1165r1.html">
 948         P1165R1 </link>
 949       </entry>
 950       <entry align="center"> 10.1 </entry>
 951       <entry />
 952     </row>
 953
 954     <row>
 955       <entry>
 956         <classname>polymorphic_allocator&lt;&gt;</classname> as a vocabulary type
 957       </entry>
 958       <entry>
 959         <link xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="https://www.open-std.org/jtc1/sc22/wg21/docs/papers/2019/p0339r6.pdf">
 960         P0339R6 </link>
 961       </entry>
 962       <entry align="center"> 9.1 </entry>
 963       <entry>
 964       <code>__cpp_lib_polymorphic_allocator &gt;= 201902L</code> (since 9.4, see Note 1)
 965       </entry>
 966     </row>
 967
 968     <row>
 969       <entry>  LWG 2511: guaranteed copy elision for piecewise construction </entry>
 970       <entry>
 971         <link xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="https://www.open-std.org/jtc1/sc22/wg21/docs/papers/2018/p0475r1.html">
 972         P0475R1 </link>
 973       </entry>
 974       <entry align="center"> 7.1 </entry>
 975       <entry />
 976     </row>
 977
 978
 979     <row>
 980       <entry namest="c1" nameend="c4" align="left">
 981         <emphasis role="bold">Miscellaneous</emphasis>
 982       </entry>
 983     </row>
 984
 985     <row>
 986       <entry>  <code>nodiscard</code> in the Library </entry>
 987       <entry>
 988         <link xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="https://www.open-std.org/jtc1/sc22/wg21/docs/papers/2017/p0600r1.pdf">
 989         P0600R1 </link>
 990       </entry>
 991       <entry align="center"> 9.1 </entry>
 992       <entry />
 993     </row>
 994
 995     <row>
 996       <entry>  de-pessimize legacy algorithms with <code>std::move</code> </entry>
 997       <entry>
 998         <link xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="https://www.open-std.org/jtc1/sc22/wg21/docs/papers/2017/p0616r0.pdf">
 999         P0616R0 </link>
1000       </entry>
1001       <entry align="center"> 9.1 </entry>
1002       <entry />
1003     </row>
1004
1005     <row>
1006       <entry>  Deprecate POD </entry>
1007       <entry>
1008         <link xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="https://www.open-std.org/jtc1/sc22/wg21/docs/papers/2017/p0767r1.html">
1009         P0767R1 </link>
1010       </entry>
1011       <entry align="center"> 10.1 </entry>
1012       <entry />
1013     </row>
1014
1015     <row>
1016       <entry>  Treating Unnecessary <code>decay</code> </entry>
1017       <entry>
1018         <link xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="https://www.open-std.org/jtc1/sc22/wg21/docs/papers/2017/p0777r1.pdf">
1019         P0777R1 </link>
1020       </entry>
1021       <entry align="center"> 9.1 </entry>
1022       <entry />
1023     </row>
1024
1025     <row>
1026       <?dbhtml bgcolor="#C8B0B0" ?>
1027       <entry>  Thou Shalt Not Specialize std Function Templates! </entry>
1028       <entry>
1029         <link xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="https://www.open-std.org/jtc1/sc22/wg21/docs/papers/2018/p0551r3.pdf">
1030         P0551R3 </link>
1031       </entry>
1032       <entry align="center"> </entry>
1033       <entry>These changes will not be implemented.</entry>
1034     </row>
1035
1036     <row>
1037       <entry>  Bit-casting object representations </entry>
1038       <entry>
1039         <link xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="https://www.open-std.org/jtc1/sc22/wg21/docs/papers/2018/p0476r2.html">
1040         P0476R2 </link>
1041       </entry>
1042       <entry align="center"> 11.1 </entry>
1043       <entry> <code>__cpp_lib_bit_cast &gt;= 201806L</code> </entry>
1044     </row>
1045
1046     <row>
1047       <entry>  Integral power-of-2 operations </entry>
1048       <entry>
1049         <link xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="https://www.open-std.org/jtc1/sc22/wg21/docs/papers/2018/p0556r3.html">
1050         P0556R3 </link>
1051       </entry>
1052       <entry align="center"> 9.1 </entry>
1053       <entry> <code>__cpp_lib_int_pow2 &gt;= 201806L</code> (since 9.4, see Note 1) </entry>
1054     </row>
1055
1056     <row>
1057       <entry> On the names of low-level bit manipulation functions </entry>
1058       <entry>
1059         <link xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="https://www.open-std.org/jtc1/sc22/wg21/docs/papers/2020/p1956r1.pdf">
1060         P1956R1 </link>
1061       </entry>
1062       <entry align="center"> 10.1 </entry>
1063       <entry> <code>__cpp_lib_int_pow2 &gt;= 202002L</code> </entry>
1064     </row>
1065
1066     <row>
1067       <entry> Safe integral comparisons </entry>
1068       <entry>
1069         <link xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="https://www.open-std.org/jtc1/sc22/wg21/docs/papers/2020/p0586r2.html">
1070         P0586R2 </link>
1071       </entry>
1072       <entry align="center"> 10.1 </entry>
1073       <entry> <code>__cpp_lib_integer_comparison_functions &gt;= 202002L</code> </entry>
1074     </row>
1075
1076     <row>
1077       <entry>  Reviewing Deprecated Facilities of C++17 for C++20 </entry>
1078       <entry>
1079         <link xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="https://www.open-std.org/jtc1/sc22/wg21/docs/papers/2018/p0619r4.html">
1080         P0619R4 </link>
1081       </entry>
1082       <entry align="center"> 12.1 </entry>
1083       <entry />
1084     </row>
1085
1086     <row>
1087       <entry>  <code>fpos</code> Requirements </entry>
1088       <entry>
1089         <link xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="https://www.open-std.org/jtc1/sc22/wg21/docs/papers/2018/p0759r1.html">
1090         P0759R1 </link>
1091       </entry>
1092       <entry align="center"> &#x2014; </entry>
1093       <entry />
1094     </row>
1095
1096     <row>
1097       <entry>  Add <code>shift</code> to <code>&lt;algorithm&gt;</code> </entry>
1098       <entry>
1099         <link xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="https://www.open-std.org/jtc1/sc22/wg21/docs/papers/2018/p0769r2.pdf">
1100         P0769R2 </link>
1101       </entry>
1102       <entry align="center"> 10.1 </entry>
1103       <entry> <code>__cpp_lib_shift &gt;= 201806L</code> </entry>
1104     </row>
1105
1106     <row>
1107       <entry>  Standard Library Specification in a Concepts and Contracts World </entry>
1108       <entry>
1109         <link xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="https://www.open-std.org/jtc1/sc22/wg21/docs/papers/2018/p0788r3.pdf">
1110         P0788R3 </link>
1111       </entry>
1112       <entry align="center"> &#x2014; </entry>
1113       <entry />
1114     </row>
1115
1116     <row>
1117       <entry>  <code>explicit(bool)</code> </entry>
1118       <entry>
1119         <link xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="https://www.open-std.org/jtc1/sc22/wg21/docs/papers/2018/p0892r2.html">
1120         P0892R2 </link>
1121       </entry>
1122       <entry align="center"> &#x2014; </entry>
1123       <entry />
1124     </row>
1125
1126     <row>
1127       <entry>  Eradicating unnecessarily explicit default constructors from the standard library </entry>
1128       <entry>
1129         <link xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="https://www.open-std.org/jtc1/sc22/wg21/docs/papers/2018/p0935r0.html">
1130         P0935R0 </link>
1131       </entry>
1132       <entry align="center"> 9.1 </entry>
1133       <entry />
1134     </row>
1135
1136     <row>
1137       <entry>  <code>std::function</code> move constructor should be <code>noexcept</code> </entry>
1138       <entry>
1139         <link xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="https://www.open-std.org/jtc1/sc22/wg21/docs/papers/2018/p0771r1.pdf">
1140         P0771R1 </link>
1141       </entry>
1142       <entry align="center"> 7.2 </entry>
1143       <entry />
1144     </row>
1145
1146     <row>
1147       <entry>  Simplified partial function application </entry>
1148       <entry>
1149         <link xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="https://www.open-std.org/jtc1/sc22/wg21/docs/papers/2018/p0356r5.html">
1150         P0356R5 </link>
1151       </entry>
1152       <entry align="center"> 9.1 </entry>
1153       <entry> <code>__cpp_lib_bind_front &gt;= 201811L</code> </entry>
1154     </row>
1155
1156     <row>
1157       <entry>  <code>bind_front</code> should not unwrap <code>reference_wrapper</code> </entry>
1158       <entry>
1159         <link xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="https://www.open-std.org/jtc1/sc22/wg21/docs/papers/2019/p1651r0.html">
1160         P1651R0 </link>
1161       </entry>
1162       <entry align="center"> 9.3 </entry>
1163       <entry> <code>__cpp_lib_bind_front &gt;= 201907L</code> </entry>
1164     </row>
1165
1166     <row>
1167       <entry>  <code>reference_wrapper</code> for incomplete types </entry>
1168       <entry>
1169         <link xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="https://www.open-std.org/jtc1/sc22/wg21/docs/papers/2018/p0357r3.html">
1170         P0357R3 </link>
1171       </entry>
1172       <entry align="center"> 9.1 </entry>
1173       <entry />
1174     </row>
1175
1176     <row>
1177       <entry>  Fixing <code>operator&gt;&gt;(basic_istream&amp;, CharT*)</code> (LWG 2499) </entry>
1178       <entry>
1179         <link xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="https://www.open-std.org/jtc1/sc22/wg21/docs/papers/2018/p0487r1.html">
1180         P0487R1 </link>
1181       </entry>
1182       <entry align="center"> 11.1 </entry>
1183       <entry />
1184     </row>
1185
1186     <row>
1187       <entry>  <code>variant</code> and <code>optional</code> should propagate copy/move triviality </entry>
1188       <entry>
1189         <link xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="https://www.open-std.org/jtc1/sc22/wg21/docs/papers/2018/p0602r4.html">
1190         P0602R4 </link>
1191       </entry>
1192       <entry align="center"> 8.3 </entry>
1193       <entry />
1194     </row>
1195
1196     <row>
1197       <entry>  A sane <code>variant</code> converting constructor </entry>
1198       <entry>
1199         <link xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="https://www.open-std.org/jtc1/sc22/wg21/docs/papers/2018/p0608r3.html">
1200         P0608R3 </link>
1201       </entry>
1202       <entry align="center"> 10.1 </entry>
1203       <entry />
1204     </row>
1205
1206     <row>
1207       <entry>  <code>visit&lt;R&gt;</code>: Explicit Return Type for <code>visit</code> </entry>
1208       <entry>
1209         <link xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="https://www.open-std.org/jtc1/sc22/wg21/docs/papers/2018/p0655r1.pdf">
1210         P0655R1 </link>
1211       </entry>
1212       <entry align="center"> 9.1 </entry>
1213       <entry />
1214     </row>
1215
1216     <row>
1217       <entry>  P0899R1 - LWG 3016 is not a defect </entry>
1218       <entry>
1219         <link xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="https://www.open-std.org/jtc1/sc22/wg21/docs/papers/2018/p0899r1.html">
1220         P0899R1 </link>
1221       </entry>
1222       <entry align="center"> 7.1 </entry>
1223       <entry />
1224     </row>
1225
1226     <row>
1227       <entry>  Editorial Guidance for merging P0019r8 and P0528r3 </entry>
1228       <entry>
1229         <link xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="https://www.open-std.org/jtc1/sc22/wg21/docs/papers/2018/p1123r0.html">
1230         P1123R0 </link>
1231       </entry>
1232       <entry align="center"> &#x2014; </entry>
1233       <entry />
1234     </row>
1235
1236     <row>
1237       <entry>  Cleaning up Clause 20 </entry>
1238       <entry>
1239         <link xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="https://www.open-std.org/jtc1/sc22/wg21/docs/papers/2018/p1148r0.pdf">
1240         P1148R0 </link>
1241       </entry>
1242       <entry align="center"> &#x2014; </entry>
1243       <entry />
1244     </row>
1245
1246     <row>
1247       <?dbhtml bgcolor="#C8B0B0" ?>
1248       <entry>  Completing the Rebase of Library Fundamentals, Version 3, Working Draft </entry>
1249       <entry>
1250         <link xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="https://www.open-std.org/jtc1/sc22/wg21/docs/papers/2018/p1210r0.html">
1251         P1210R0 </link>
1252       </entry>
1253       <entry align="center"> </entry>
1254       <entry />
1255     </row>
1256
1257     <row>
1258       <entry>  Alternative Wording for P0907R4 Signed Integers are Two's Complement </entry>
1259       <entry>
1260         <link xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="https://www.open-std.org/jtc1/sc22/wg21/docs/papers/2018/p1236r1.html">
1261         P1236R1 </link>
1262       </entry>
1263       <entry align="center"> &#x2014; </entry>
1264       <entry/>
1265     </row>
1266
1267     <row>
1268       <entry>
1269         I Stream, You Stream, We All Stream for
1270         <classname>istream_iterator</classname>
1271       </entry>
1272       <entry>
1273         <link xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="https://www.open-std.org/jtc1/sc22/wg21/docs/papers/2019/p0738r2.html">
1274         P0738R2 </link>
1275       </entry>
1276       <entry align="center"> 10.1 </entry>
1277       <entry />
1278     </row>
1279
1280     <row>
1281       <entry>
1282         Mandating the Standard Library:
1283         Clause 16 - Language support library
1284       </entry>
1285       <entry>
1286         <link xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="https://www.open-std.org/jtc1/sc22/wg21/docs/papers/2019/p1458r1.pdf">
1287         P1458R1 </link>
1288       </entry>
1289       <entry align="center"> &#x2014; </entry>
1290       <entry/>
1291     </row>
1292
1293     <row>
1294       <entry>
1295         Mandating the Standard Library:
1296         Clause 18 - Diagnostics library
1297       </entry>
1298       <entry>
1299         <link xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="https://www.open-std.org/jtc1/sc22/wg21/docs/papers/2019/p1458r1.pdf">
1300         P1459R1 </link>
1301       </entry>
1302       <entry align="center"> &#x2014; </entry>
1303       <entry/>
1304     </row>
1305
1306     <row>
1307       <entry>
1308         Mandating the Standard Library:
1309         Clause 20 - Strings library
1310       </entry>
1311       <entry>
1312         <link xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="https://www.open-std.org/jtc1/sc22/wg21/docs/papers/2019/p1462r1.html">
1313         P1462R1 </link>
1314       </entry>
1315       <entry align="center"> &#x2014; </entry>
1316       <entry/>
1317     </row>
1318
1319     <row>
1320       <entry>
1321         Mandating the Standard Library:
1322         Clause 21 - Containers library
1323       </entry>
1324       <entry>
1325         <link xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="https://www.open-std.org/jtc1/sc22/wg21/docs/papers/2019/p1463r1.pdf">
1326         P1463R1 </link>
1327       </entry>
1328       <entry align="center"> 10.1 </entry>
1329       <entry/>
1330     </row>
1331
1332     <row>
1333       <entry>
1334         Mandating the Standard Library:
1335         Clause 22 - Iterators library
1336       </entry>
1337       <entry>
1338         <link xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="https://www.open-std.org/jtc1/sc22/wg21/docs/papers/2019/p1464r1.pdf">
1339         P1464R1 </link>
1340       </entry>
1341       <entry align="center"> &#x2014; </entry>
1342       <entry />
1343     </row>
1344
1345     <row>
1346       <entry> Make <code>create_directory()</code> Intuitive </entry>
1347       <entry>
1348         <link xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="https://www.open-std.org/jtc1/sc22/wg21/docs/papers/2019/p1164r1.pdf">
1349         P1164R1
1350   </link>
1351       </entry>
1352       <entry align="center"> 8.3 </entry>
1353       <entry> Treated as a DR for C++17 </entry>
1354     </row>
1355
1356     <row>
1357       <entry>
1358         Target Vectorization Policies from Parallelism V2 TS to C++20
1359       </entry>
1360       <entry>
1361         <link xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="https://www.open-std.org/jtc1/sc22/wg21/docs/papers/2019/p1001r2.html">
1362         P1001R2 </link>
1363       </entry>
1364       <entry align="center"> 9.1 </entry>
1365       <entry> <code>__cpp_lib_execution &gt;= 201902L</code> (since 9.4, see Note 1)</entry>
1366     </row>
1367
1368     <row>
1369       <entry> Merge Coroutines TS into C++20 working draft </entry>
1370       <entry>
1371         <link xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="https://www.open-std.org/jtc1/sc22/wg21/docs/papers/2019/p0912r5.html">
1372         P0912R5 </link>
1373       </entry>
1374       <entry align="center"> 10.1 </entry>
1375       <entry> <code>__cpp_lib_coroutines &gt;= 201902L</code> </entry>
1376     </row>
1377
1378     <row>
1379       <entry>  Endian just Endian </entry>
1380       <entry>
1381         <link xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="https://www.open-std.org/jtc1/sc22/wg21/docs/papers/2017/p0463r1.html">
1382         P0463R1 </link>
1383       </entry>
1384       <entry align="center"> 8.1 </entry>
1385       <entry> <code>__cpp_lib_endian &gt;= 201907L</code> </entry>
1386     </row>
1387
1388     <row>
1389       <entry> Bit operations </entry>
1390       <entry>
1391         <link xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="https://www.open-std.org/jtc1/sc22/wg21/docs/papers/2019/p0553r4.html">
1392         P0553R4 </link>
1393       </entry>
1394       <entry align="center"> 9.1 </entry>
1395       <entry> <code>__cpp_lib_bitops &gt;= 201907L</code> (since 9.4, see Note 1) </entry>
1396     </row>
1397
1398     <row>
1399       <entry>  Well-behaved interpolation for numbers and pointers </entry>
1400       <entry>
1401         <link xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="https://www.open-std.org/jtc1/sc22/wg21/docs/papers/2019/p0811r3.html">
1402         P0811R3 </link>
1403       </entry>
1404       <entry align="center"> 9.1 </entry>
1405       <entry> <code>__cpp_lib_interpolate &gt;= 201902L</code> </entry>
1406     </row>
1407
1408     <row>
1409       <entry> Mathematical constants </entry>
1410       <entry>
1411         <link xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="https://www.open-std.org/jtc1/sc22/wg21/docs/papers/2019/p0631r8.pdf">
1412         P0631R8 </link>
1413       </entry>
1414       <entry align="center"> 10.1 </entry>
1415       <entry> <code>__cpp_lib_math_constants &gt;= 201907L</code> </entry>
1416     </row>
1417
1418     <row>
1419       <entry> std::source_location </entry>
1420       <entry>
1421         <link xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="https://www.open-std.org/jtc1/sc22/wg21/docs/papers/2019/p1208r6.pdf">
1422         P1208R6 </link>
1423       </entry>
1424       <entry align="center"> 11.1 </entry>
1425       <entry>
1426         <code>__cpp_lib_source_location &gt;= 201907L</code>
1427       </entry>
1428     </row>
1429
1430     <row>
1431       <entry> Efficient access to std::basic_stringbuf's Buffer </entry>
1432       <entry>
1433         <link xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="https://www.open-std.org/jtc1/sc22/wg21/docs/papers/2019/p0408r7.pdf">
1434         P0408R7 </link>
1435       </entry>
1436       <entry align="center"> 11.1 </entry>
1437       <entry />
1438     </row>
1439
1440   </tbody>
1441 </tgroup>
1442 </table>
1443
1444 <para>
1445 Note 1: This feature is supported in older releases but the
1446 <code>__cpp_lib</code> macro is not defined to the right value
1447 (or not defined at all) until the version shown in parentheses.
1448 </para>
1449
1450 <para>
1451 Note 2: The C++20 calendar types are supported since 11.1,
1452 time zones and UTC are supported since 13.1,
1453 and <function>chrono::parse</function> is supported since 14.1.
1454 </para>
1455
1456 </section>