master
   1// -*- C++ -*-
   2//===----------------------------------------------------------------------===//
   3//
   4// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
   5// See https://llvm.org/LICENSE.txt for license information.
   6// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
   7//
   8//===----------------------------------------------------------------------===//
   9
  10#ifndef _LIBCPP_CHRONO
  11#define _LIBCPP_CHRONO
  12
  13// clang-format off
  14
  15/*
  16    chrono synopsis
  17
  18#include <compare> // C++20
  19
  20namespace std
  21{
  22namespace chrono
  23{
  24
  25template <class ToDuration, class Rep, class Period>
  26constexpr
  27ToDuration
  28duration_cast(const duration<Rep, Period>& fd);
  29
  30template <class Rep> struct treat_as_floating_point : is_floating_point<Rep> {};
  31
  32template <class Rep> inline constexpr bool treat_as_floating_point_v
  33    = treat_as_floating_point<Rep>::value;                       // C++17
  34
  35template <class Rep>
  36struct duration_values
  37{
  38public:
  39    static constexpr Rep zero(); // noexcept in C++20
  40    static constexpr Rep max();  // noexcept in C++20
  41    static constexpr Rep min();  // noexcept in C++20
  42};
  43
  44// duration
  45
  46template <class Rep, class Period = ratio<1>>
  47class duration
  48{
  49    static_assert(!__is_duration<Rep>::value, "A duration representation can not be a duration");
  50    static_assert(__is_ratio<Period>::value, "Second template parameter of duration must be a std::ratio");
  51    static_assert(Period::num > 0, "duration period must be positive");
  52public:
  53    typedef Rep rep;
  54    typedef typename _Period::type period;
  55
  56    constexpr duration() = default;
  57    template <class Rep2>
  58        constexpr explicit duration(const Rep2& r,
  59            typename enable_if
  60            <
  61               is_convertible<const Rep2&, rep>::value &&
  62               (treat_as_floating_point<rep>::value ||
  63               !treat_as_floating_point<rep>::value && !treat_as_floating_point<Rep2>::value)
  64            >::type* = 0);
  65
  66    // conversions
  67    template <class Rep2, class Period2>
  68        constexpr duration(const duration<Rep2, Period2>& d,
  69            typename enable_if
  70            <
  71                treat_as_floating_point<rep>::value ||
  72                ratio_divide<Period2, period>::type::den == 1
  73            >::type* = 0);
  74
  75    // observer
  76
  77    constexpr rep count() const;
  78
  79    // arithmetic
  80
  81    constexpr common_type<duration>::type  operator+() const;
  82    constexpr common_type<duration>::type  operator-() const;
  83    constexpr duration& operator++();    // constexpr in C++17
  84    constexpr duration  operator++(int); // constexpr in C++17
  85    constexpr duration& operator--();    // constexpr in C++17
  86    constexpr duration  operator--(int); // constexpr in C++17
  87
  88    constexpr duration& operator+=(const duration& d);  // constexpr in C++17
  89    constexpr duration& operator-=(const duration& d);  // constexpr in C++17
  90
  91    duration& operator*=(const rep& rhs);       // constexpr in C++17
  92    duration& operator/=(const rep& rhs);       // constexpr in C++17
  93    duration& operator%=(const rep& rhs);       // constexpr in C++17
  94    duration& operator%=(const duration& rhs);  // constexpr in C++17
  95
  96    // special values
  97
  98    static constexpr duration zero(); // noexcept in C++20
  99    static constexpr duration min();  // noexcept in C++20
 100    static constexpr duration max();  // noexcept in C++20
 101};
 102
 103typedef duration<long long,         nano> nanoseconds;
 104typedef duration<long long,        micro> microseconds;
 105typedef duration<long long,        milli> milliseconds;
 106typedef duration<long long              > seconds;
 107typedef duration<     long, ratio<  60> > minutes;
 108typedef duration<     long, ratio<3600> > hours;
 109
 110template <class Clock, class Duration = typename Clock::duration>
 111class time_point
 112{
 113public:
 114    typedef Clock                     clock;
 115    typedef Duration                  duration;
 116    typedef typename duration::rep    rep;
 117    typedef typename duration::period period;
 118private:
 119    duration d_;  // exposition only
 120
 121public:
 122    time_point();  // has value "epoch" // constexpr in C++14
 123    explicit time_point(const duration& d);  // same as time_point() + d // constexpr in C++14
 124
 125    // conversions
 126    template <class Duration2>
 127       time_point(const time_point<clock, Duration2>& t); // constexpr in C++14
 128
 129    // observer
 130
 131    duration time_since_epoch() const; // constexpr in C++14
 132
 133    // arithmetic
 134
 135    constexpr time_point& operator++();    // C++20
 136    constexpr time_point  operator++(int); // C++20
 137    constexpr time_point& operator--();    // C++20
 138    constexpr time_point  operator--(int); // C++20
 139
 140    time_point& operator+=(const duration& d); // constexpr in C++17
 141    time_point& operator-=(const duration& d); // constexpr in C++17
 142
 143    // special values
 144
 145    static constexpr time_point min();  // noexcept in C++20
 146    static constexpr time_point max();  // noexcept in C++20
 147};
 148
 149} // chrono
 150
 151// common_type traits
 152template <class Rep1, class Period1, class Rep2, class Period2>
 153  struct common_type<chrono::duration<Rep1, Period1>, chrono::duration<Rep2, Period2>>;
 154
 155template <class Clock, class Duration1, class Duration2>
 156  struct common_type<chrono::time_point<Clock, Duration1>, chrono::time_point<Clock, Duration2>>;
 157
 158namespace chrono {
 159
 160// duration arithmetic
 161template <class Rep1, class Period1, class Rep2, class Period2>
 162  constexpr
 163  typename common_type<duration<Rep1, Period1>, duration<Rep2, Period2>>::type
 164  operator+(const duration<Rep1, Period1>& lhs, const duration<Rep2, Period2>& rhs);
 165template <class Rep1, class Period1, class Rep2, class Period2>
 166  constexpr
 167  typename common_type<duration<Rep1, Period1>, duration<Rep2, Period2>>::type
 168  operator-(const duration<Rep1, Period1>& lhs, const duration<Rep2, Period2>& rhs);
 169template <class Rep1, class Period, class Rep2>
 170  constexpr
 171  duration<typename common_type<Rep1, Rep2>::type, Period>
 172  operator*(const duration<Rep1, Period>& d, const Rep2& s);
 173template <class Rep1, class Period, class Rep2>
 174  constexpr
 175  duration<typename common_type<Rep1, Rep2>::type, Period>
 176  operator*(const Rep1& s, const duration<Rep2, Period>& d);
 177template <class Rep1, class Period, class Rep2>
 178  constexpr
 179  duration<typename common_type<Rep1, Rep2>::type, Period>
 180  operator/(const duration<Rep1, Period>& d, const Rep2& s);
 181template <class Rep1, class Period1, class Rep2, class Period2>
 182  constexpr
 183  typename common_type<Rep1, Rep2>::type
 184  operator/(const duration<Rep1, Period1>& lhs, const duration<Rep2, Period2>& rhs);
 185
 186// duration comparisons
 187template <class Rep1, class Period1, class Rep2, class Period2>
 188   constexpr
 189   bool operator==(const duration<Rep1, Period1>& lhs, const duration<Rep2, Period2>& rhs);
 190template <class Rep1, class Period1, class Rep2, class Period2>
 191   constexpr
 192   bool operator!=(const duration<Rep1, Period1>& lhs, const duration<Rep2, Period2>& rhs); // removed in C++20
 193template <class Rep1, class Period1, class Rep2, class Period2>
 194   constexpr
 195   bool operator< (const duration<Rep1, Period1>& lhs, const duration<Rep2, Period2>& rhs);
 196template <class Rep1, class Period1, class Rep2, class Period2>
 197   constexpr
 198   bool operator<=(const duration<Rep1, Period1>& lhs, const duration<Rep2, Period2>& rhs);
 199template <class Rep1, class Period1, class Rep2, class Period2>
 200   constexpr
 201   bool operator> (const duration<Rep1, Period1>& lhs, const duration<Rep2, Period2>& rhs);
 202template <class Rep1, class Period1, class Rep2, class Period2>
 203   constexpr
 204   bool operator>=(const duration<Rep1, Period1>& lhs, const duration<Rep2, Period2>& rhs);
 205template<class Rep1, class Period1, class Rep2, class Period2>
 206  requires three_way_comparable<typename CT::rep>
 207  constexpr auto operator<=>(const duration<Rep1, Period1>& lhs,
 208                             const duration<Rep2, Period2>& rhs);                           // since C++20
 209
 210// duration_cast
 211template <class ToDuration, class Rep, class Period>
 212  ToDuration duration_cast(const duration<Rep, Period>& d);
 213
 214template <class ToDuration, class Rep, class Period>
 215    constexpr ToDuration floor(const duration<Rep, Period>& d);    // C++17
 216template <class ToDuration, class Rep, class Period>
 217    constexpr ToDuration ceil(const duration<Rep, Period>& d);     // C++17
 218template <class ToDuration, class Rep, class Period>
 219    constexpr ToDuration round(const duration<Rep, Period>& d);    // C++17
 220
 221// duration I/O
 222template<class charT, class traits, class Rep, class Period>       // C++20
 223  basic_ostream<charT, traits>&
 224    operator<<(basic_ostream<charT, traits>& os,
 225               const duration<Rep, Period>& d);
 226
 227// time_point arithmetic (all constexpr in C++14)
 228template <class Clock, class Duration1, class Rep2, class Period2>
 229  time_point<Clock, typename common_type<Duration1, duration<Rep2, Period2>>::type>
 230  operator+(const time_point<Clock, Duration1>& lhs, const duration<Rep2, Period2>& rhs);
 231template <class Rep1, class Period1, class Clock, class Duration2>
 232  time_point<Clock, typename common_type<duration<Rep1, Period1>, Duration2>::type>
 233  operator+(const duration<Rep1, Period1>& lhs, const time_point<Clock, Duration2>& rhs);
 234template <class Clock, class Duration1, class Rep2, class Period2>
 235  time_point<Clock, typename common_type<Duration1, duration<Rep2, Period2>>::type>
 236  operator-(const time_point<Clock, Duration1>& lhs, const duration<Rep2, Period2>& rhs);
 237template <class Clock, class Duration1, class Duration2>
 238  typename common_type<Duration1, Duration2>::type
 239  operator-(const time_point<Clock, Duration1>& lhs, const time_point<Clock, Duration2>& rhs);
 240
 241// time_point comparisons (all constexpr in C++14)
 242template <class Clock, class Duration1, class Duration2>
 243   bool operator==(const time_point<Clock, Duration1>& lhs, const time_point<Clock, Duration2>& rhs);
 244template <class Clock, class Duration1, class Duration2>
 245   bool operator!=(const time_point<Clock, Duration1>& lhs, const time_point<Clock, Duration2>& rhs); // removed in C++20
 246template <class Clock, class Duration1, class Duration2>
 247   bool operator< (const time_point<Clock, Duration1>& lhs, const time_point<Clock, Duration2>& rhs);
 248template <class Clock, class Duration1, class Duration2>
 249   bool operator<=(const time_point<Clock, Duration1>& lhs, const time_point<Clock, Duration2>& rhs);
 250template <class Clock, class Duration1, class Duration2>
 251   bool operator> (const time_point<Clock, Duration1>& lhs, const time_point<Clock, Duration2>& rhs);
 252template <class Clock, class Duration1, class Duration2>
 253   bool operator>=(const time_point<Clock, Duration1>& lhs, const time_point<Clock, Duration2>& rhs);
 254template<class Clock, class Duration1,
 255         three_way_comparable_with<Duration1> Duration2>
 256  constexpr auto operator<=>(const time_point<Clock, Duration1>& lhs,
 257                             const time_point<Clock, Duration2>& rhs);                                // since C++20
 258
 259// time_point_cast (constexpr in C++14)
 260
 261template <class ToDuration, class Clock, class Duration>
 262  time_point<Clock, ToDuration> time_point_cast(const time_point<Clock, Duration>& t);
 263
 264template <class ToDuration, class Clock, class Duration>
 265    constexpr time_point<Clock, ToDuration>
 266    floor(const time_point<Clock, Duration>& tp);                  // C++17
 267
 268template <class ToDuration, class Clock, class Duration>
 269    constexpr time_point<Clock, ToDuration>
 270    ceil(const time_point<Clock, Duration>& tp);                   // C++17
 271
 272template <class ToDuration, class Clock, class Duration>
 273    constexpr time_point<Clock, ToDuration>
 274    round(const time_point<Clock, Duration>& tp);                  // C++17
 275
 276template <class Rep, class Period>
 277    constexpr duration<Rep, Period> abs(duration<Rep, Period> d);  // C++17
 278
 279// Clocks
 280
 281class system_clock
 282{
 283public:
 284    typedef microseconds                     duration;
 285    typedef duration::rep                    rep;
 286    typedef duration::period                 period;
 287    typedef chrono::time_point<system_clock> time_point;
 288    static const bool is_steady =            false; // constexpr in C++14
 289
 290    static time_point now() noexcept;
 291    static time_t     to_time_t  (const time_point& __t) noexcept;
 292    static time_point from_time_t(time_t __t) noexcept;
 293};
 294
 295template <class Duration>
 296  using sys_time  = time_point<system_clock, Duration>; // C++20
 297using sys_seconds = sys_time<seconds>;                  // C++20
 298using sys_days    = sys_time<days>;                     // C++20
 299
 300template<class charT, class traits, class Duration>     // C++20
 301  basic_ostream<charT, traits>&
 302    operator<<(basic_ostream<charT, traits>& os, const sys_time<Duration>& tp);
 303
 304template<class charT, class traits>                    // C++20
 305  basic_ostream<charT, traits>&
 306    operator<<(basic_ostream<charT, traits>& os, const sys_days& dp);
 307
 308// [time.clock.utc], class utc_clock
 309class utc_clock {                                      // C++20
 310public:
 311    using rep                       = a signed arithmetic type;
 312    using period                    = ratio<unspecified, unspecified>;
 313    using duration                  = chrono::duration<rep, period>;
 314    using time_point                = chrono::time_point<utc_clock>;
 315    static constexpr bool is_steady = unspecified;
 316
 317    static time_point now();
 318
 319    template<class Duration>
 320      static sys_time<common_type_t<Duration, seconds>>
 321        to_sys(const utc_time<Duration>& t);
 322    template<class Duration>
 323      static utc_time<common_type_t<Duration, seconds>>
 324        from_sys(const sys_time<Duration>& t);
 325};
 326
 327template<class Duration>
 328using utc_time  = time_point<utc_clock, Duration>;      // C++20
 329using utc_seconds = utc_time<seconds>;                  // C++20
 330
 331template<class charT, class traits, class Duration>     // C++20
 332  basic_ostream<charT, traits>&
 333    operator<<(basic_ostream<charT, traits>& os, const utc_time<Duration>& t);
 334
 335struct leap_second_info {                               // C++20
 336  bool    is_leap_second;
 337  seconds elapsed;
 338};
 339
 340template<class Duration>                                // C++20
 341  leap_second_info get_leap_second_info(const utc_time<Duration>& ut);
 342
 343
 344// [time.clock.tai], class tai_clock
 345class tai_clock {                                      // C++20
 346public:
 347    using rep                       = a signed arithmetic type;
 348    using period                    = ratio<unspecified, unspecified>;
 349    using duration                  = chrono::duration<rep, period>;
 350    using time_point                = chrono::time_point<tai_clock>;
 351    static constexpr bool is_steady = unspecified;
 352
 353    static time_point now();
 354
 355    template<class Duration>
 356      static utc_time<common_type_t<Duration, seconds>>
 357        to_utc(const tai_time<Duration>& t);
 358    template<class Duration>
 359      static tai_time<common_type_t<Duration, seconds>>
 360        from_utc(const utc_time<Duration>& t);
 361};
 362
 363template<class Duration>
 364using tai_time  = time_point<tai_clock, Duration>;      // C++20
 365using tai_seconds = tai_time<seconds>;                  // C++20
 366
 367template<class charT, class traits, class Duration>     // C++20
 368  basic_ostream<charT, traits>&
 369    operator<<(basic_ostream<charT, traits>& os, const tai_time<Duration>& t);
 370
 371// [time.clock.gps], class gps_clock
 372class gps_clock {                                      // C++20
 373public:
 374    using rep                       = a signed arithmetic type;
 375    using period                    = ratio<unspecified, unspecified>;
 376    using duration                  = chrono::duration<rep, period>;
 377    using time_point                = chrono::time_point<gps_clock>;
 378    static constexpr bool is_steady = unspecified;
 379
 380    static time_point now();
 381
 382    template<class Duration>
 383      static utc_time<common_type_t<Duration, seconds>>
 384        to_utc(const gps_time<Duration>& t);
 385    template<class Duration>
 386      static gps_time<common_type_t<Duration, seconds>>
 387        from_utc(const utc_time<Duration>& t);
 388};
 389
 390template<class Duration>
 391using gps_time  = time_point<gps_clock, Duration>;      // C++20
 392using gps_seconds = gps_time<seconds>;                  // C++20
 393
 394template<class charT, class traits, class Duration>     // C++20
 395  basic_ostream<charT, traits>&
 396    operator<<(basic_ostream<charT, traits>& os, const gps_time<Duration>& t);
 397
 398class file_clock                                        // C++20
 399{
 400public:
 401    typedef see-below                      rep;
 402    typedef nano                           period;
 403    typedef chrono::duration<rep, period>  duration;
 404    typedef chrono::time_point<file_clock> time_point;
 405    static constexpr bool is_steady =      false;
 406
 407    static time_point now() noexcept;
 408
 409    template<class Duration>
 410    static sys_time<see-below> to_sys(const file_time<Duration>&);
 411
 412    template<class Duration>
 413    static file_time<see-below> from_sys(const sys_time<Duration>&);
 414};
 415
 416template<class Duration>
 417  using file_time = time_point<file_clock, Duration>;   // C++20
 418
 419template<class charT, class traits, class Duration>     // C++20
 420  basic_ostream<charT, traits>&
 421    operator<<(basic_ostream<charT, traits>& os, const file_time<Duration>& tp);
 422
 423class steady_clock
 424{
 425public:
 426    typedef nanoseconds                                   duration;
 427    typedef duration::rep                                 rep;
 428    typedef duration::period                              period;
 429    typedef chrono::time_point<steady_clock, duration>    time_point;
 430    static const bool is_steady =                         true; // constexpr in C++14
 431
 432    static time_point now() noexcept;
 433};
 434
 435typedef steady_clock high_resolution_clock;
 436
 437// [time.clock.local] local time           // C++20
 438struct local_t {};
 439template<class Duration>
 440  using local_time  = time_point<local_t, Duration>;
 441using local_seconds = local_time<seconds>;
 442using local_days    = local_time<days>;
 443
 444template<class charT, class traits, class Duration>     // C++20
 445  basic_ostream<charT, traits>&
 446    operator<<(basic_ostream<charT, traits>& os, const local_time<Duration>& tp);
 447
 448// [time.cal.last] class last_spec    // C++20
 449struct last_spec;
 450
 451// [time.cal.day] class day          // C++20
 452
 453class day;
 454constexpr bool operator==(const day& x, const day& y) noexcept;
 455constexpr strong_ordering operator<=>(const day& x, const day& y) noexcept;
 456constexpr day  operator+(const day&  x, const days& y) noexcept;
 457constexpr day  operator+(const days& x, const day&  y) noexcept;
 458constexpr day  operator-(const day&  x, const days& y) noexcept;
 459constexpr days operator-(const day&  x, const day&  y) noexcept;
 460template<class charT, class traits>
 461  basic_ostream<charT, traits>&
 462    operator<<(basic_ostream<charT, traits>& os, const day& d);
 463
 464// [time.cal.month] class month    // C++20
 465class month;
 466constexpr bool operator==(const month& x, const month& y) noexcept;
 467constexpr strong_ordering operator<=>(const month& x, const month& y) noexcept;
 468
 469constexpr month  operator+(const month&  x, const months& y) noexcept;
 470constexpr month  operator+(const months& x,  const month& y) noexcept;
 471constexpr month  operator-(const month&  x, const months& y) noexcept;
 472constexpr months operator-(const month&  x,  const month& y) noexcept;
 473template<class charT, class traits>
 474  basic_ostream<charT, traits>&
 475    operator<<(basic_ostream<charT, traits>& os, const month& m);
 476
 477// [time.cal.year] class year    // C++20
 478class year;
 479constexpr bool operator==(const year& x, const year& y) noexcept;
 480constexpr strong_ordering operator<=>(const year& x, const year& y) noexcept;
 481
 482constexpr year  operator+(const year&  x, const years& y) noexcept;
 483constexpr year  operator+(const years& x, const year&  y) noexcept;
 484constexpr year  operator-(const year&  x, const years& y) noexcept;
 485constexpr years operator-(const year&  x, const year&  y) noexcept;
 486template<class charT, class traits>
 487  basic_ostream<charT, traits>&
 488    operator<<(basic_ostream<charT, traits>& os, const year& y);
 489
 490// [time.cal.wd] class weekday    // C++20
 491class weekday;
 492
 493constexpr bool operator==(const weekday& x, const weekday& y) noexcept;
 494constexpr weekday operator+(const weekday& x, const days&    y) noexcept;
 495constexpr weekday operator+(const days&    x, const weekday& y) noexcept;
 496constexpr weekday operator-(const weekday& x, const days&    y) noexcept;
 497constexpr days    operator-(const weekday& x, const weekday& y) noexcept;
 498template<class charT, class traits>
 499  basic_ostream<charT, traits>&
 500    operator<<(basic_ostream<charT, traits>& os, const weekday& wd);
 501
 502// [time.cal.wdidx] class weekday_indexed    // C++20
 503
 504class weekday_indexed;
 505constexpr bool operator==(const weekday_indexed& x, const weekday_indexed& y) noexcept;
 506
 507template<class charT, class traits>
 508  basic_ostream<charT, traits>&
 509    operator<<(basic_ostream<charT, traits>& os, const weekday_indexed& wdi);
 510
 511// [time.cal.wdlast] class weekday_last    // C++20
 512class weekday_last;
 513
 514constexpr bool operator==(const weekday_last& x, const weekday_last& y) noexcept;
 515
 516template<class charT, class traits>
 517  basic_ostream<charT, traits>&
 518    operator<<(basic_ostream<charT, traits>& os, const weekday_last& wdl);
 519
 520// [time.cal.md] class month_day    // C++20
 521class month_day;
 522
 523constexpr bool operator==(const month_day& x, const month_day& y) noexcept;
 524constexpr strong_ordering operator<=>(const month_day& x, const month_day& y) noexcept;
 525
 526template<class charT, class traits>
 527  basic_ostream<charT, traits>&
 528    operator<<(basic_ostream<charT, traits>& os, const month_day& md);
 529
 530// [time.cal.mdlast] class month_day_last    // C++20
 531class month_day_last;
 532
 533constexpr bool operator==(const month_day_last& x, const month_day_last& y) noexcept;
 534constexpr strong_ordering operator<=>(const month_day_last& x, const month_day_last& y) noexcept;
 535
 536template<class charT, class traits>
 537  basic_ostream<charT, traits>&
 538    operator<<(basic_ostream<charT, traits>& os, const month_day_last& mdl);
 539
 540// [time.cal.mwd] class month_weekday    // C++20
 541class month_weekday;
 542
 543constexpr bool operator==(const month_weekday& x, const month_weekday& y) noexcept;
 544
 545template<class charT, class traits>
 546  basic_ostream<charT, traits>&
 547    operator<<(basic_ostream<charT, traits>& os, const month_weekday& mwd);
 548
 549// [time.cal.mwdlast] class month_weekday_last    // C++20
 550class month_weekday_last;
 551
 552constexpr bool operator==(const month_weekday_last& x, const month_weekday_last& y) noexcept;
 553
 554template<class charT, class traits>
 555  basic_ostream<charT, traits>&
 556    operator<<(basic_ostream<charT, traits>& os, const month_weekday_last& mwdl);
 557
 558
 559// [time.cal.ym] class year_month    // C++20
 560class year_month;
 561
 562constexpr bool operator==(const year_month& x, const year_month& y) noexcept;
 563constexpr strong_ordering operator<=>(const year_month& x, const year_month& y) noexcept;
 564
 565constexpr year_month operator+(const year_month& ym, const months& dm) noexcept;
 566constexpr year_month operator+(const months& dm, const year_month& ym) noexcept;
 567constexpr year_month operator-(const year_month& ym, const months& dm) noexcept;
 568constexpr months operator-(const year_month& x, const year_month& y) noexcept;
 569constexpr year_month operator+(const year_month& ym, const years& dy) noexcept;
 570constexpr year_month operator+(const years& dy, const year_month& ym) noexcept;
 571constexpr year_month operator-(const year_month& ym, const years& dy) noexcept;
 572
 573template<class charT, class traits>
 574  basic_ostream<charT, traits>&
 575    operator<<(basic_ostream<charT, traits>& os, const year_month& ym);
 576
 577// [time.cal.ymd] class year_month_day class    // C++20
 578year_month_day;
 579
 580constexpr bool operator==(const year_month_day& x, const year_month_day& y) noexcept;
 581constexpr strong_ordering operator<=>(const year_month_day& x, const year_month_day& y) noexcept;
 582
 583constexpr year_month_day operator+(const year_month_day& ymd, const months& dm) noexcept;
 584constexpr year_month_day operator+(const months& dm, const year_month_day& ymd) noexcept;
 585constexpr year_month_day operator+(const year_month_day& ymd, const years& dy) noexcept;
 586constexpr year_month_day operator+(const years& dy, const year_month_day& ymd) noexcept;
 587constexpr year_month_day operator-(const year_month_day& ymd, const months& dm) noexcept;
 588constexpr year_month_day operator-(const year_month_day& ymd, const years& dy) noexcept;
 589
 590template<class charT, class traits>
 591  basic_ostream<charT, traits>&
 592    operator<<(basic_ostream<charT, traits>& os, const year_month_day& ymd);
 593
 594// [time.cal.ymdlast] class year_month_day_last    // C++20
 595class year_month_day_last;
 596
 597constexpr bool operator==(const year_month_day_last& x, const year_month_day_last& y) noexcept;
 598constexpr strong_ordering operator<=>(const year_month_day_last_day& x, const year_month_day_last_day& y) noexcept;
 599
 600constexpr year_month_day_last
 601  operator+(const year_month_day_last& ymdl, const months& dm) noexcept;
 602constexpr year_month_day_last
 603  operator+(const months& dm, const year_month_day_last& ymdl) noexcept;
 604constexpr year_month_day_last
 605  operator+(const year_month_day_last& ymdl, const years& dy) noexcept;
 606constexpr year_month_day_last
 607  operator+(const years& dy, const year_month_day_last& ymdl) noexcept;
 608constexpr year_month_day_last
 609  operator-(const year_month_day_last& ymdl, const months& dm) noexcept;
 610constexpr year_month_day_last
 611  operator-(const year_month_day_last& ymdl, const years& dy) noexcept;
 612
 613template<class charT, class traits>
 614  basic_ostream<charT, traits>&
 615    operator<<(basic_ostream<charT, traits>& os, const year_month_day_last& ymdl);
 616
 617// [time.cal.ymwd] class year_month_weekday    // C++20
 618class year_month_weekday;
 619
 620constexpr bool operator==(const year_month_weekday& x,
 621                          const year_month_weekday& y) noexcept;
 622
 623constexpr year_month_weekday
 624  operator+(const year_month_weekday& ymwd, const months& dm) noexcept;
 625constexpr year_month_weekday
 626  operator+(const months& dm, const year_month_weekday& ymwd) noexcept;
 627constexpr year_month_weekday
 628  operator+(const year_month_weekday& ymwd, const years& dy) noexcept;
 629constexpr year_month_weekday
 630  operator+(const years& dy, const year_month_weekday& ymwd) noexcept;
 631constexpr year_month_weekday
 632  operator-(const year_month_weekday& ymwd, const months& dm) noexcept;
 633constexpr year_month_weekday
 634  operator-(const year_month_weekday& ymwd, const years& dy) noexcept;
 635
 636template<class charT, class traits>
 637  basic_ostream<charT, traits>&
 638    operator<<(basic_ostream<charT, traits>& os, const year_month_weekday& ymwd);
 639
 640// [time.cal.ymwdlast] class year_month_weekday_last    // C++20
 641class year_month_weekday_last;
 642
 643constexpr bool operator==(const year_month_weekday_last& x,
 644                          const year_month_weekday_last& y) noexcept;
 645constexpr year_month_weekday_last
 646  operator+(const year_month_weekday_last& ymwdl, const months& dm) noexcept;
 647constexpr year_month_weekday_last
 648  operator+(const months& dm, const year_month_weekday_last& ymwdl) noexcept;
 649constexpr year_month_weekday_last
 650  operator+(const year_month_weekday_last& ymwdl, const years& dy) noexcept;
 651constexpr year_month_weekday_last
 652  operator+(const years& dy, const year_month_weekday_last& ymwdl) noexcept;
 653constexpr year_month_weekday_last
 654  operator-(const year_month_weekday_last& ymwdl, const months& dm) noexcept;
 655constexpr year_month_weekday_last
 656  operator-(const year_month_weekday_last& ymwdl, const years& dy) noexcept;
 657
 658template<class charT, class traits>
 659  basic_ostream<charT, traits>&
 660    operator<<(basic_ostream<charT, traits>& os, const year_month_weekday_last& ymwdl);
 661
 662// [time.cal.operators] civil calendar conventional syntax operators    // C++20
 663constexpr year_month
 664  operator/(const year& y, const month& m) noexcept;
 665constexpr year_month
 666  operator/(const year& y, int m) noexcept;
 667constexpr month_day
 668  operator/(const month& m, const day& d) noexcept;
 669constexpr month_day
 670  operator/(const month& m, int d) noexcept;
 671constexpr month_day
 672  operator/(int m, const day& d) noexcept;
 673constexpr month_day
 674  operator/(const day& d, const month& m) noexcept;
 675constexpr month_day
 676  operator/(const day& d, int m) noexcept;
 677constexpr month_day_last
 678  operator/(const month& m, last_spec) noexcept;
 679constexpr month_day_last
 680  operator/(int m, last_spec) noexcept;
 681constexpr month_day_last
 682  operator/(last_spec, const month& m) noexcept;
 683constexpr month_day_last
 684  operator/(last_spec, int m) noexcept;
 685constexpr month_weekday
 686  operator/(const month& m, const weekday_indexed& wdi) noexcept;
 687constexpr month_weekday
 688  operator/(int m, const weekday_indexed& wdi) noexcept;
 689constexpr month_weekday
 690  operator/(const weekday_indexed& wdi, const month& m) noexcept;
 691constexpr month_weekday
 692  operator/(const weekday_indexed& wdi, int m) noexcept;
 693constexpr month_weekday_last
 694  operator/(const month& m, const weekday_last& wdl) noexcept;
 695constexpr month_weekday_last
 696  operator/(int m, const weekday_last& wdl) noexcept;
 697constexpr month_weekday_last
 698  operator/(const weekday_last& wdl, const month& m) noexcept;
 699constexpr month_weekday_last
 700  operator/(const weekday_last& wdl, int m) noexcept;
 701constexpr year_month_day
 702  operator/(const year_month& ym, const day& d) noexcept;
 703constexpr year_month_day
 704  operator/(const year_month& ym, int d) noexcept;
 705constexpr year_month_day
 706  operator/(const year& y, const month_day& md) noexcept;
 707constexpr year_month_day
 708  operator/(int y, const month_day& md) noexcept;
 709constexpr year_month_day
 710  operator/(const month_day& md, const year& y) noexcept;
 711constexpr year_month_day
 712  operator/(const month_day& md, int y) noexcept;
 713constexpr year_month_day_last
 714  operator/(const year_month& ym, last_spec) noexcept;
 715constexpr year_month_day_last
 716  operator/(const year& y, const month_day_last& mdl) noexcept;
 717constexpr year_month_day_last
 718  operator/(int y, const month_day_last& mdl) noexcept;
 719constexpr year_month_day_last
 720  operator/(const month_day_last& mdl, const year& y) noexcept;
 721constexpr year_month_day_last
 722  operator/(const month_day_last& mdl, int y) noexcept;
 723constexpr year_month_weekday
 724  operator/(const year_month& ym, const weekday_indexed& wdi) noexcept;
 725constexpr year_month_weekday
 726  operator/(const year& y, const month_weekday& mwd) noexcept;
 727constexpr year_month_weekday
 728  operator/(int y, const month_weekday& mwd) noexcept;
 729constexpr year_month_weekday
 730  operator/(const month_weekday& mwd, const year& y) noexcept;
 731constexpr year_month_weekday
 732  operator/(const month_weekday& mwd, int y) noexcept;
 733constexpr year_month_weekday_last
 734  operator/(const year_month& ym, const weekday_last& wdl) noexcept;
 735constexpr year_month_weekday_last
 736  operator/(const year& y, const month_weekday_last& mwdl) noexcept;
 737constexpr year_month_weekday_last
 738  operator/(int y, const month_weekday_last& mwdl) noexcept;
 739constexpr year_month_weekday_last
 740  operator/(const month_weekday_last& mwdl, const year& y) noexcept;
 741constexpr year_month_weekday_last
 742  operator/(const month_weekday_last& mwdl, int y) noexcept;
 743
 744// 26.9, class template hh_mm_ss
 745template <class Duration>
 746class hh_mm_ss
 747{
 748    bool            is_neg; // exposition only
 749    chrono::hours   h;      // exposition only
 750    chrono::minutes m;      // exposition only
 751    chrono::seconds s;      // exposition only
 752    precision       ss;     // exposition only
 753
 754public:
 755    static unsigned constexpr fractional_width = see below;
 756    using precision                            = see below;
 757
 758    constexpr hh_mm_ss() noexcept : hh_mm_ss{Duration::zero()} {}
 759    constexpr explicit hh_mm_ss(Duration d) noexcept;
 760
 761    constexpr bool is_negative() const noexcept;
 762    constexpr chrono::hours hours() const noexcept;
 763    constexpr chrono::minutes minutes() const noexcept;
 764    constexpr chrono::seconds seconds() const noexcept;
 765    constexpr precision subseconds() const noexcept;
 766
 767    constexpr explicit operator  precision()   const noexcept;
 768    constexpr          precision to_duration() const noexcept;
 769};
 770
 771template<class charT, class traits, class Duration>
 772  basic_ostream<charT, traits>&
 773    operator<<(basic_ostream<charT, traits>& os, const hh_mm_ss<Duration>& hms); // C++20
 774
 775// 26.10, 12/24 hour functions
 776constexpr bool is_am(hours const& h) noexcept;
 777constexpr bool is_pm(hours const& h) noexcept;
 778constexpr hours make12(const hours& h) noexcept;
 779constexpr hours make24(const hours& h, bool is_pm) noexcept;
 780
 781// [time.zone.db], time zone database
 782struct tzdb {                                                                    // C++20
 783  string                 version;
 784  vector<time_zone>      zones;
 785  vector<time_zone_link> links;
 786  vector<leap_second>    leap_seconds;
 787
 788  const time_zone* locate_zone(string_view tz_name) const;
 789  const time_zone* current_zone() const;
 790};
 791
 792class tzdb_list {                                                                // C++20
 793public:
 794  tzdb_list(const tzdb_list&) = delete;
 795  tzdb_list& operator=(const tzdb_list&) = delete;
 796
 797  // unspecified additional constructors
 798
 799  class const_iterator;
 800
 801  const tzdb& front() const noexcept;
 802
 803  const_iterator erase_after(const_iterator p);
 804
 805  const_iterator begin() const noexcept;
 806  const_iterator end()   const noexcept;
 807
 808  const_iterator cbegin() const noexcept;
 809  const_iterator cend()   const noexcept;
 810};
 811
 812// [time.zone.db.access], time zone database access
 813const tzdb& get_tzdb();                                                          // C++20
 814tzdb_list& get_tzdb_list();                                                      // C++20
 815const time_zone* locate_zone(string_view tz_name);                               // C++20
 816const time_zone* current_zone()                                                  // C++20
 817
 818// [time.zone.db.remote], remote time zone database support
 819const tzdb& reload_tzdb();                                                       // C++20
 820string remote_version();                                                         // C++20
 821
 822// [time.zone.exception], exception classes
 823class nonexistent_local_time;                                                    // C++20
 824class ambiguous_local_time;                                                      // C++20
 825
 826// [time.zone.info], information classes
 827struct sys_info {                                                                // C++20
 828  sys_seconds   begin;
 829  sys_seconds   end;
 830  seconds       offset;
 831  minutes       save;
 832  string        abbrev;
 833};
 834
 835template<class charT, class traits>                                              // C++20
 836  basic_ostream<charT, traits>&
 837    operator<<(basic_ostream<charT, traits>& os, const sys_info& si);
 838
 839struct local_info {                                                             // C++20
 840  static constexpr int unique      = 0;
 841  static constexpr int nonexistent = 1;
 842  static constexpr int ambiguous   = 2;
 843
 844  int result;
 845  sys_info first;
 846  sys_info second;
 847};
 848
 849template<class charT, class traits>                                              // C++20
 850  basic_ostream<charT, traits>&
 851    operator<<(basic_ostream<charT, traits>& os, const local_info& li);
 852
 853// [time.zone.timezone] class time_zone                                                      // C++20
 854enum class choose {earliest, latest};
 855class time_zone {
 856  time_zone(time_zone&&) = default;
 857  time_zone& operator=(time_zone&&) = default;
 858
 859  // unspecified additional constructors
 860
 861  string_view name() const noexcept;
 862
 863  template<class Duration>
 864  sys_info get_info(const sys_time<Duration>& st) const;
 865
 866  template<class Duration>
 867  local_info get_info(const local_time<Duration>& tp) const;
 868
 869  template<class Duration>
 870  sys_time<common_type_t<Duration, seconds>>
 871    to_sys(const local_time<Duration>& tp) const;
 872
 873  template<class Duration>
 874  sys_time<common_type_t<Duration, seconds>>
 875    to_sys(const local_time<Duration>& tp, choose z) const;
 876
 877  template<class Duration>
 878  local_time<common_type_t<Duration, seconds>>
 879    to_local(const sys_time<Duration>& tp) const;
 880};
 881bool operator==(const time_zone& x, const time_zone& y) noexcept;                // C++20
 882strong_ordering operator<=>(const time_zone& x, const time_zone& y) noexcept;    // C++20
 883
 884// [time.zone.zonedtraits], class template zoned_traits
 885template<class T> struct zoned_traits;                                           // C++20
 886
 887// [time.zone.zonedtime], class template zoned_time
 888template<class Duration, class TimeZonePtr = const time_zone*>                   // C++20
 889class zoned_time;
 890
 891using zoned_seconds = zoned_time<seconds>;                                       // C++20
 892
 893template<class Duration1, class Duration2, class TimeZonePtr>                    // C++20
 894  bool operator==(const zoned_time<Duration1, TimeZonePtr>& x,
 895                  const zoned_time<Duration2, TimeZonePtr>& y);
 896
 897template<class charT, class traits, class Duration, class TimeZonePtr>           // C++20
 898  basic_ostream<charT, traits>&
 899    operator<<(basic_ostream<charT, traits>& os,
 900               const zoned_time<Duration, TimeZonePtr>& t);
 901
 902// [time.zone.leap], leap second support
 903class leap_second {                                                              // C++20
 904public:
 905  leap_second(const leap_second&)            = default;
 906  leap_second& operator=(const leap_second&) = default;
 907
 908  // unspecified additional constructors
 909
 910  constexpr sys_seconds date() const noexcept;
 911  constexpr seconds value() const noexcept;
 912};
 913
 914constexpr bool operator==(const leap_second& x, const leap_second& y);           // C++20
 915constexpr strong_ordering operator<=>(const leap_second& x, const leap_second& y);
 916
 917template<class Duration>                                                         // C++20
 918  constexpr bool operator==(const leap_second& x, const sys_time<Duration>& y);
 919template<class Duration>                                                         // C++20
 920  constexpr bool operator< (const leap_second& x, const sys_time<Duration>& y);
 921template<class Duration>                                                         // C++20
 922  constexpr bool operator< (const sys_time<Duration>& x, const leap_second& y);
 923template<class Duration>                                                         // C++20
 924  constexpr bool operator> (const leap_second& x, const sys_time<Duration>& y);
 925template<class Duration>                                                         // C++20
 926  constexpr bool operator> (const sys_time<Duration>& x, const leap_second& y);
 927template<class Duration>                                                         // C++20
 928  constexpr bool operator<=(const leap_second& x, const sys_time<Duration>& y);
 929template<class Duration>                                                         // C++20
 930  constexpr bool operator<=(const sys_time<Duration>& x, const leap_second& y);
 931template<class Duration>                                                         // C++20
 932  constexpr bool operator>=(const leap_second& x, const sys_time<Duration>& y);
 933template<class Duration>                                                         // C++20
 934  constexpr bool operator>=(const sys_time<Duration>& x, const leap_second& y);
 935template<class Duration>                                                         // C++20
 936  requires three_way_comparable_with<sys_seconds, sys_time<Duration>>
 937  constexpr auto operator<=>(const leap_second& x, const sys_time<Duration>& y);
 938
 939// [time.zone.link], class time_zone_link
 940class time_zone_link {                                                           // C++20
 941public:
 942  time_zone_link(time_zone_link&&)            = default;
 943  time_zone_link& operator=(time_zone_link&&) = default;
 944
 945  // unspecified additional constructors
 946
 947  string_view name()   const noexcept;
 948  string_view target() const noexcept;
 949};
 950
 951bool operator==(const time_zone_link& x, const time_zone_link& y);               // C++20
 952strong_ordering operator<=>(const time_zone_link& x, const time_zone_link& y);   // C++20
 953
 954}  // chrono
 955
 956namespace std {
 957  template<class Rep, class Period, class charT>
 958    struct formatter<chrono::duration<Rep, Period>, charT>;                       // C++20
 959  template<class Duration, class charT>
 960    struct formatter<chrono::sys_time<Duration>, charT>;                          // C++20
 961  template<class Duration, class charT>
 962    struct formatter<chrono::utc_time<Duration>, charT>;                          // C++20
 963  template<class Duration, class charT>
 964    struct formatter<chrono::tai_time<Duration>, charT>;                          // C++20
 965  template<class Duration, class charT>
 966    struct formatter<chrono::gps_time<Duration>, charT>;                          // C++20
 967  template<class Duration, class charT>
 968    struct formatter<chrono::file_time<Duration>, charT>;                         // C++20
 969  template<class Duration, class charT>
 970    struct formatter<chrono::local_time<Duration>, charT>;                        // C++20
 971  template<class charT> struct formatter<chrono::day, charT>;                     // C++20
 972  template<class charT> struct formatter<chrono::month, charT>;                   // C++20
 973  template<class charT> struct formatter<chrono::year, charT>;                    // C++20
 974  template<class charT> struct formatter<chrono::weekday, charT>;                 // C++20
 975  template<class charT> struct formatter<chrono::weekday_indexed, charT>;         // C++20
 976  template<class charT> struct formatter<chrono::weekday_last, charT>;            // C++20
 977  template<class charT> struct formatter<chrono::month_day, charT>;               // C++20
 978  template<class charT> struct formatter<chrono::month_day_last, charT>;          // C++20
 979  template<class charT> struct formatter<chrono::month_weekday, charT>;           // C++20
 980  template<class charT> struct formatter<chrono::month_weekday_last, charT>;      // C++20
 981  template<class charT> struct formatter<chrono::year_month, charT>;              // C++20
 982  template<class charT> struct formatter<chrono::year_month_day, charT>;          // C++20
 983  template<class charT> struct formatter<chrono::year_month_day_last, charT>;     // C++20
 984  template<class charT> struct formatter<chrono::year_month_weekday, charT>;      // C++20
 985  template<class charT> struct formatter<chrono::year_month_weekday_last, charT>; // C++20
 986  template<class Rep, class Period, class charT>
 987    struct formatter<chrono::hh_mm_ss<duration<Rep, Period>>, charT>;             // C++20
 988  template<class charT> struct formatter<chrono::sys_info, charT>;                // C++20
 989  template<class charT> struct formatter<chrono::local_info, charT>;              // C++20
 990  template<class Duration, class TimeZonePtr, class charT>                        // C++20
 991    struct formatter<chrono::zoned_time<Duration, TimeZonePtr>, charT>;
 992} // namespace std
 993
 994namespace chrono {
 995// calendrical constants
 996inline constexpr last_spec                              last{};       // C++20
 997inline constexpr chrono::weekday                        Sunday{0};    // C++20
 998inline constexpr chrono::weekday                        Monday{1};    // C++20
 999inline constexpr chrono::weekday                        Tuesday{2};   // C++20
1000inline constexpr chrono::weekday                        Wednesday{3}; // C++20
1001inline constexpr chrono::weekday                        Thursday{4};  // C++20
1002inline constexpr chrono::weekday                        Friday{5};    // C++20
1003inline constexpr chrono::weekday                        Saturday{6};  // C++20
1004
1005inline constexpr chrono::month                          January{1};   // C++20
1006inline constexpr chrono::month                          February{2};  // C++20
1007inline constexpr chrono::month                          March{3};     // C++20
1008inline constexpr chrono::month                          April{4};     // C++20
1009inline constexpr chrono::month                          May{5};       // C++20
1010inline constexpr chrono::month                          June{6};      // C++20
1011inline constexpr chrono::month                          July{7};      // C++20
1012inline constexpr chrono::month                          August{8};    // C++20
1013inline constexpr chrono::month                          September{9}; // C++20
1014inline constexpr chrono::month                          October{10};  // C++20
1015inline constexpr chrono::month                          November{11}; // C++20
1016inline constexpr chrono::month                          December{12}; // C++20
1017}  // chrono
1018
1019inline namespace literals {
1020  inline namespace chrono_literals {
1021constexpr chrono::hours                                 operator ""h(unsigned long long); // C++14
1022constexpr chrono::duration<unspecified , ratio<3600,1>> operator ""h(long double); // C++14
1023constexpr chrono::minutes                               operator ""min(unsigned long long); // C++14
1024constexpr chrono::duration<unspecified , ratio<60,1>>   operator ""min(long double); // C++14
1025constexpr chrono::seconds                               operator ""s(unsigned long long); // C++14
1026constexpr chrono::duration<unspecified >                operator ""s(long double); // C++14
1027constexpr chrono::milliseconds                          operator ""ms(unsigned long long); // C++14
1028constexpr chrono::duration<unspecified , milli>         operator ""ms(long double); // C++14
1029constexpr chrono::microseconds                          operator ""us(unsigned long long); // C++14
1030constexpr chrono::duration<unspecified , micro>         operator ""us(long double); // C++14
1031constexpr chrono::nanoseconds                           operator ""ns(unsigned long long); // C++14
1032constexpr chrono::duration<unspecified , nano>          operator ""ns(long double); // C++14
1033constexpr chrono::day                                   operator ""d(unsigned long long d) noexcept; // C++20
1034constexpr chrono::year                                  operator ""y(unsigned long long y) noexcept; // C++20
1035}  // chrono_literals
1036}  // literals
1037
1038}  // std
1039*/
1040
1041// clang-format on
1042
1043#if __cplusplus < 201103L && defined(_LIBCPP_USE_FROZEN_CXX03_HEADERS)
1044#  include <__cxx03/chrono>
1045#else
1046#  include <__config>
1047
1048#  include <__chrono/duration.h>
1049#  include <__chrono/file_clock.h>
1050#  include <__chrono/high_resolution_clock.h>
1051#  include <__chrono/steady_clock.h>
1052#  include <__chrono/system_clock.h>
1053#  include <__chrono/time_point.h>
1054
1055#  if _LIBCPP_STD_VER >= 20
1056#    include <__chrono/calendar.h>
1057#    include <__chrono/day.h>
1058#    include <__chrono/exception.h>
1059#    include <__chrono/hh_mm_ss.h>
1060#    include <__chrono/literals.h>
1061#    include <__chrono/local_info.h>
1062#    include <__chrono/month.h>
1063#    include <__chrono/month_weekday.h>
1064#    include <__chrono/monthday.h>
1065#    include <__chrono/sys_info.h>
1066#    include <__chrono/weekday.h>
1067#    include <__chrono/year.h>
1068#    include <__chrono/year_month.h>
1069#    include <__chrono/year_month_day.h>
1070#    include <__chrono/year_month_weekday.h>
1071
1072#    if _LIBCPP_HAS_LOCALIZATION
1073#      include <__chrono/formatter.h>
1074#      include <__chrono/ostream.h>
1075#      include <__chrono/parser_std_format_spec.h>
1076#      include <__chrono/statically_widen.h>
1077#    endif
1078
1079#    if _LIBCPP_HAS_TIME_ZONE_DATABASE && _LIBCPP_HAS_FILESYSTEM && _LIBCPP_HAS_LOCALIZATION
1080#      include <__chrono/gps_clock.h>
1081#      include <__chrono/leap_second.h>
1082#      include <__chrono/tai_clock.h>
1083#      include <__chrono/time_zone.h>
1084#      include <__chrono/time_zone_link.h>
1085#      include <__chrono/tzdb.h>
1086#      include <__chrono/tzdb_list.h>
1087#      include <__chrono/utc_clock.h>
1088#      include <__chrono/zoned_time.h>
1089#    endif
1090
1091#  endif
1092
1093#  include <version>
1094
1095// standard-mandated includes
1096
1097// [time.syn]
1098#  include <compare>
1099
1100#  if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
1101#    pragma GCC system_header
1102#  endif
1103
1104#  if !defined(_LIBCPP_REMOVE_TRANSITIVE_INCLUDES) && _LIBCPP_STD_VER <= 17
1105#    include <cstdint>
1106#    include <stdexcept>
1107#    include <string_view>
1108#  endif
1109
1110#  if !defined(_LIBCPP_REMOVE_TRANSITIVE_INCLUDES) && _LIBCPP_STD_VER <= 20
1111#    include <bit>
1112#    include <concepts>
1113#    include <cstring>
1114#    include <forward_list>
1115#    include <string>
1116#    include <tuple>
1117#    include <vector>
1118#  endif
1119
1120#  if !defined(_LIBCPP_REMOVE_TRANSITIVE_INCLUDES) && _LIBCPP_STD_VER == 20
1121#    include <charconv>
1122#    if _LIBCPP_HAS_LOCALIZATION
1123#      include <locale>
1124#      include <ostream>
1125#    endif
1126#  endif
1127#endif // __cplusplus < 201103L && defined(_LIBCPP_USE_FROZEN_CXX03_HEADERS)
1128
1129#endif // _LIBCPP_CHRONO