Upgrade to 2022-era LLVM LIBCXX

third_party/libcxx/src/algorithm.cpp

@@ -0,0 +1,47 @@
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#include <algorithm>
+#include <bit>
+
+_LIBCPP_BEGIN_NAMESPACE_STD
+
+template <class Comp, class RandomAccessIterator>
+void __sort(RandomAccessIterator first, RandomAccessIterator last, Comp comp) {
+  auto depth_limit = 2 * std::__bit_log2(static_cast<size_t>(last - first));
+
+  // Only use bitset partitioning for arithmetic types.  We should also check
+  // that the default comparator is in use so that we are sure that there are no
+  // branches in the comparator.
+  std::__introsort<_ClassicAlgPolicy,
+                   Comp&,
+                   RandomAccessIterator,
+                   __use_branchless_sort<Comp, RandomAccessIterator>::value>(first, last, comp, depth_limit);
+}
+
+// clang-format off
+template void __sort<__less<char>&, char*>(char*, char*, __less<char>&);
+#ifndef _LIBCPP_HAS_NO_WIDE_CHARACTERS
+template void __sort<__less<wchar_t>&, wchar_t*>(wchar_t*, wchar_t*, __less<wchar_t>&);
+#endif
+template void __sort<__less<signed char>&, signed char*>(signed char*, signed char*, __less<signed char>&);
+template void __sort<__less<unsigned char>&, unsigned char*>(unsigned char*, unsigned char*, __less<unsigned char>&);
+template void __sort<__less<short>&, short*>(short*, short*, __less<short>&);
+template void __sort<__less<unsigned short>&, unsigned short*>(unsigned short*, unsigned short*, __less<unsigned short>&);
+template void __sort<__less<int>&, int*>(int*, int*, __less<int>&);
+template void __sort<__less<unsigned>&, unsigned*>(unsigned*, unsigned*, __less<unsigned>&);
+template void __sort<__less<long>&, long*>(long*, long*, __less<long>&);
+template void __sort<__less<unsigned long>&, unsigned long*>(unsigned long*, unsigned long*, __less<unsigned long>&);
+template void __sort<__less<long long>&, long long*>(long long*, long long*, __less<long long>&);
+template void __sort<__less<unsigned long long>&, unsigned long long*>(unsigned long long*, unsigned long long*, __less<unsigned long long>&);
+template void __sort<__less<float>&, float*>(float*, float*, __less<float>&);
+template void __sort<__less<double>&, double*>(double*, double*, __less<double>&);
+template void __sort<__less<long double>&, long double*>(long double*, long double*, __less<long double>&);
+// clang-format on
+
+_LIBCPP_END_NAMESPACE_STD

third_party/libcxx/src/any.cpp

@@ -0,0 +1,34 @@
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#include <any>
+
+namespace std {
+const char* bad_any_cast::what() const noexcept {
+    return "bad any cast";
+}
+}
+
+
+#include <experimental/__config>
+
+//  Preserve std::experimental::any_bad_cast for ABI compatibility
+//  Even though it no longer exists in a header file
+_LIBCPP_BEGIN_NAMESPACE_LFTS
+
+class _LIBCPP_EXCEPTION_ABI _LIBCPP_AVAILABILITY_BAD_ANY_CAST bad_any_cast : public bad_cast
+{
+public:
+    virtual const char* what() const noexcept;
+};
+
+const char* bad_any_cast::what() const noexcept {
+    return "bad any cast";
+}
+
+_LIBCPP_END_NAMESPACE_LFTS

third_party/libcxx/src/atomic.cpp

@@ -0,0 +1,220 @@
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#include <__config>
+#ifndef _LIBCPP_HAS_NO_THREADS
+
+#include <atomic>
+#include <climits>
+#include <functional>
+#include <thread>
+
+#ifdef __linux__
+
+#include <unistd.h>
+#include <linux/futex.h>
+#include <sys/syscall.h>
+
+// libc++ uses SYS_futex as a universal syscall name. However, on 32 bit architectures
+// with a 64 bit time_t, we need to specify SYS_futex_time64.
+#if !defined(SYS_futex) && defined(SYS_futex_time64)
+# define SYS_futex SYS_futex_time64
+#endif
+
+#elif defined(__FreeBSD__)
+
+#include <sys/types.h>
+#include <sys/umtx.h>
+
+#else // <- Add other operating systems here
+
+// Baseline needs no new headers
+
+#endif
+
+_LIBCPP_BEGIN_NAMESPACE_STD
+
+#ifdef __linux__
+
+static void __libcpp_platform_wait_on_address(__cxx_atomic_contention_t const volatile* __ptr,
+                                              __cxx_contention_t __val)
+{
+    static constexpr timespec __timeout = { 2, 0 };
+    syscall(SYS_futex, __ptr, FUTEX_WAIT_PRIVATE, __val, &__timeout, 0, 0);
+}
+
+static void __libcpp_platform_wake_by_address(__cxx_atomic_contention_t const volatile* __ptr,
+                                              bool __notify_one)
+{
+    syscall(SYS_futex, __ptr, FUTEX_WAKE_PRIVATE, __notify_one ? 1 : INT_MAX, 0, 0, 0);
+}
+
+#elif defined(__APPLE__) && defined(_LIBCPP_USE_ULOCK)
+
+extern "C" int __ulock_wait(uint32_t operation, void *addr, uint64_t value,
+                            uint32_t timeout); /* timeout is specified in microseconds */
+extern "C" int __ulock_wake(uint32_t operation, void *addr, uint64_t wake_value);
+
+#define UL_COMPARE_AND_WAIT 1
+#define ULF_WAKE_ALL        0x00000100
+
+static void __libcpp_platform_wait_on_address(__cxx_atomic_contention_t const volatile* __ptr,
+                                              __cxx_contention_t __val)
+{
+    __ulock_wait(UL_COMPARE_AND_WAIT,
+                 const_cast<__cxx_atomic_contention_t*>(__ptr), __val, 0);
+}
+
+static void __libcpp_platform_wake_by_address(__cxx_atomic_contention_t const volatile* __ptr,
+                                              bool __notify_one)
+{
+    __ulock_wake(UL_COMPARE_AND_WAIT | (__notify_one ? 0 : ULF_WAKE_ALL),
+                 const_cast<__cxx_atomic_contention_t*>(__ptr), 0);
+}
+
+#elif defined(__FreeBSD__) && __SIZEOF_LONG__ == 8
+/*
+ * Since __cxx_contention_t is int64_t even on 32bit FreeBSD
+ * platforms, we have to use umtx ops that work on the long type, and
+ * limit its use to architectures where long and int64_t are synonyms.
+ */
+
+static void __libcpp_platform_wait_on_address(__cxx_atomic_contention_t const volatile* __ptr,
+                                              __cxx_contention_t __val)
+{
+    _umtx_op(const_cast<__cxx_atomic_contention_t*>(__ptr),
+             UMTX_OP_WAIT, __val, NULL, NULL);
+}
+
+static void __libcpp_platform_wake_by_address(__cxx_atomic_contention_t const volatile* __ptr,
+                                              bool __notify_one)
+{
+    _umtx_op(const_cast<__cxx_atomic_contention_t*>(__ptr),
+             UMTX_OP_WAKE, __notify_one ? 1 : INT_MAX, NULL, NULL);
+}
+
+#else // <- Add other operating systems here
+
+// Baseline is just a timed backoff
+
+static void __libcpp_platform_wait_on_address(__cxx_atomic_contention_t const volatile* __ptr,
+                                              __cxx_contention_t __val)
+{
+    __libcpp_thread_poll_with_backoff([=]() -> bool {
+        return !__cxx_nonatomic_compare_equal(__cxx_atomic_load(__ptr, memory_order_relaxed), __val);
+    }, __libcpp_timed_backoff_policy());
+}
+
+static void __libcpp_platform_wake_by_address(__cxx_atomic_contention_t const volatile*, bool) { }
+
+#endif // __linux__
+
+static constexpr size_t __libcpp_contention_table_size = (1 << 8);  /* < there's no magic in this number */
+
+struct alignas(64) /*  aim to avoid false sharing */ __libcpp_contention_table_entry
+{
+    __cxx_atomic_contention_t __contention_state;
+    __cxx_atomic_contention_t __platform_state;
+    inline constexpr __libcpp_contention_table_entry() :
+        __contention_state(0), __platform_state(0) { }
+};
+
+static __libcpp_contention_table_entry __libcpp_contention_table[ __libcpp_contention_table_size ];
+
+static hash<void const volatile*> __libcpp_contention_hasher;
+
+static __libcpp_contention_table_entry* __libcpp_contention_state(void const volatile * p)
+{
+    return &__libcpp_contention_table[__libcpp_contention_hasher(p) & (__libcpp_contention_table_size - 1)];
+}
+
+/* Given an atomic to track contention and an atomic to actually wait on, which may be
+   the same atomic, we try to detect contention to avoid spuriously calling the platform. */
+
+static void __libcpp_contention_notify(__cxx_atomic_contention_t volatile* __contention_state,
+                                       __cxx_atomic_contention_t const volatile* __platform_state,
+                                       bool __notify_one)
+{
+    if(0 != __cxx_atomic_load(__contention_state, memory_order_seq_cst))
+        // We only call 'wake' if we consumed a contention bit here.
+        __libcpp_platform_wake_by_address(__platform_state, __notify_one);
+}
+static __cxx_contention_t __libcpp_contention_monitor_for_wait(__cxx_atomic_contention_t volatile* __contention_state,
+                                                               __cxx_atomic_contention_t const volatile* __platform_state)
+{
+    // We will monitor this value.
+    return __cxx_atomic_load(__platform_state, memory_order_acquire);
+}
+static void __libcpp_contention_wait(__cxx_atomic_contention_t volatile* __contention_state,
+                                     __cxx_atomic_contention_t const volatile* __platform_state,
+                                     __cxx_contention_t __old_value)
+{
+    __cxx_atomic_fetch_add(__contention_state, __cxx_contention_t(1), memory_order_seq_cst);
+    // We sleep as long as the monitored value hasn't changed.
+    __libcpp_platform_wait_on_address(__platform_state, __old_value);
+    __cxx_atomic_fetch_sub(__contention_state, __cxx_contention_t(1), memory_order_release);
+}
+
+/* When the incoming atomic is the wrong size for the platform wait size, need to
+   launder the value sequence through an atomic from our table. */
+
+static void __libcpp_atomic_notify(void const volatile* __location)
+{
+    auto const __entry = __libcpp_contention_state(__location);
+    // The value sequence laundering happens on the next line below.
+    __cxx_atomic_fetch_add(&__entry->__platform_state, __cxx_contention_t(1), memory_order_release);
+    __libcpp_contention_notify(&__entry->__contention_state,
+                               &__entry->__platform_state,
+                               false /* when laundering, we can't handle notify_one */);
+}
+_LIBCPP_EXPORTED_FROM_ABI
+void __cxx_atomic_notify_one(void const volatile* __location)
+    { __libcpp_atomic_notify(__location); }
+_LIBCPP_EXPORTED_FROM_ABI
+void __cxx_atomic_notify_all(void const volatile* __location)
+    { __libcpp_atomic_notify(__location); }
+_LIBCPP_EXPORTED_FROM_ABI
+__cxx_contention_t __libcpp_atomic_monitor(void const volatile* __location)
+{
+    auto const __entry = __libcpp_contention_state(__location);
+    return __libcpp_contention_monitor_for_wait(&__entry->__contention_state, &__entry->__platform_state);
+}
+_LIBCPP_EXPORTED_FROM_ABI
+void __libcpp_atomic_wait(void const volatile* __location, __cxx_contention_t __old_value)
+{
+    auto const __entry = __libcpp_contention_state(__location);
+    __libcpp_contention_wait(&__entry->__contention_state, &__entry->__platform_state, __old_value);
+}
+
+/* When the incoming atomic happens to be the platform wait size, we still need to use the
+   table for the contention detection, but we can use the atomic directly for the wait. */
+
+_LIBCPP_EXPORTED_FROM_ABI
+void __cxx_atomic_notify_one(__cxx_atomic_contention_t const volatile* __location)
+{
+    __libcpp_contention_notify(&__libcpp_contention_state(__location)->__contention_state, __location, true);
+}
+_LIBCPP_EXPORTED_FROM_ABI
+void __cxx_atomic_notify_all(__cxx_atomic_contention_t const volatile* __location)
+{
+    __libcpp_contention_notify(&__libcpp_contention_state(__location)->__contention_state, __location, false);
+}
+_LIBCPP_EXPORTED_FROM_ABI
+__cxx_contention_t __libcpp_atomic_monitor(__cxx_atomic_contention_t const volatile* __location)
+{
+    return __libcpp_contention_monitor_for_wait(&__libcpp_contention_state(__location)->__contention_state, __location);
+}
+_LIBCPP_EXPORTED_FROM_ABI
+void __libcpp_atomic_wait(__cxx_atomic_contention_t const volatile* __location, __cxx_contention_t __old_value)
+{
+    __libcpp_contention_wait(&__libcpp_contention_state(__location)->__contention_state, __location, __old_value);
+}
+
+_LIBCPP_END_NAMESPACE_STD
+
+#endif //_LIBCPP_HAS_NO_THREADS

third_party/libcxx/src/barrier.cpp

@@ -0,0 +1,97 @@
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#include <__config>
+
+#ifndef _LIBCPP_HAS_NO_THREADS
+
+#include <barrier>
+#include <thread>
+
+_LIBCPP_BEGIN_NAMESPACE_STD
+
+#if !defined(_LIBCPP_HAS_NO_TREE_BARRIER)
+
+class __barrier_algorithm_base {
+public:
+    struct alignas(64) /* naturally-align the heap state */ __state_t
+    {
+        struct {
+          __atomic_base<__barrier_phase_t> __phase{0};
+        } __tickets[64];
+    };
+
+    ptrdiff_t&              __expected;
+    unique_ptr<__state_t[]> __state;
+
+    _LIBCPP_HIDDEN
+    __barrier_algorithm_base(ptrdiff_t& __expected)
+        : __expected(__expected)
+    {
+        size_t const __count = (__expected + 1) >> 1;
+        __state = unique_ptr<__state_t[]>(new __state_t[__count]);
+    }
+    _LIBCPP_HIDDEN
+    bool __arrive(__barrier_phase_t __old_phase)
+    {
+        __barrier_phase_t const __half_step = __old_phase + 1,
+                                __full_step = __old_phase + 2;
+        size_t __current_expected = __expected,
+            __current = hash<thread::id>()(this_thread::get_id()) % ((__expected + 1) >> 1);
+        for(int __round = 0;; ++__round) {
+            if(__current_expected <= 1)
+                return true;
+            size_t const __end_node = ((__current_expected + 1) >> 1),
+                         __last_node = __end_node - 1;
+            for(;;++__current) {
+                if(__current == __end_node)
+                __current = 0;
+                __barrier_phase_t expect = __old_phase;
+                if(__current == __last_node && (__current_expected & 1))
+                {
+                    if(__state[__current].__tickets[__round].__phase.compare_exchange_strong(expect, __full_step, memory_order_acq_rel))
+                        break;    // I'm 1 in 1, go to next __round
+                }
+                else if(__state[__current].__tickets[__round].__phase.compare_exchange_strong(expect, __half_step, memory_order_acq_rel))
+                {
+                    return false; // I'm 1 in 2, done with arrival
+                }
+                else if(expect == __half_step)
+                {
+                    if(__state[__current].__tickets[__round].__phase.compare_exchange_strong(expect, __full_step, memory_order_acq_rel))
+                        break;    // I'm 2 in 2, go to next __round
+                }
+            }
+            __current_expected = __last_node + 1;
+            __current >>= 1;
+        }
+    }
+};
+
+_LIBCPP_EXPORTED_FROM_ABI
+__barrier_algorithm_base * __construct_barrier_algorithm_base(ptrdiff_t& __expected)
+{
+    return new __barrier_algorithm_base(__expected);
+}
+_LIBCPP_EXPORTED_FROM_ABI
+bool __arrive_barrier_algorithm_base(__barrier_algorithm_base* __barrier,
+                                     __barrier_phase_t __old_phase)
+{
+    return __barrier->__arrive(__old_phase);
+}
+_LIBCPP_EXPORTED_FROM_ABI
+void __destroy_barrier_algorithm_base(__barrier_algorithm_base* __barrier)
+{
+    delete __barrier;
+}
+
+#endif // !defined(_LIBCPP_HAS_NO_TREE_BARRIER)
+
+_LIBCPP_END_NAMESPACE_STD
+
+#endif //_LIBCPP_HAS_NO_THREADS

third_party/libcxx/src/bind.cpp

@@ -0,0 +1,29 @@
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#include <functional>
+
+_LIBCPP_BEGIN_NAMESPACE_STD
+
+namespace placeholders
+{
+
+const __ph<1>   _1{};
+const __ph<2>   _2{};
+const __ph<3>   _3{};
+const __ph<4>   _4{};
+const __ph<5>   _5{};
+const __ph<6>   _6{};
+const __ph<7>   _7{};
+const __ph<8>   _8{};
+const __ph<9>   _9{};
+const __ph<10> _10{};
+
+}  // placeholders
+
+_LIBCPP_END_NAMESPACE_STD

third_party/libcxx/src/charconv.cpp

@@ -0,0 +1,86 @@
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#include <charconv>
+#include <string.h>
+
+#include "third_party/libcxx/src/include/to_chars_floating_point.h"
+
+_LIBCPP_BEGIN_NAMESPACE_STD
+
+#ifndef _LIBCPP_ABI_DO_NOT_EXPORT_TO_CHARS_BASE_10
+
+namespace __itoa
+{
+
+_LIBCPP_FUNC_VIS char*
+__u32toa(uint32_t value, char* buffer) noexcept
+{
+  return __base_10_u32(buffer, value);
+}
+
+_LIBCPP_FUNC_VIS char*
+__u64toa(uint64_t value, char* buffer) noexcept
+{
+  return __base_10_u64(buffer, value);
+}
+
+}  // namespace __itoa
+
+#endif // _LIBCPP_ABI_DO_NOT_EXPORT_TO_CHARS_BASE_10
+
+// The original version of floating-point to_chars was written by Microsoft and
+// contributed with the following license.
+
+// Copyright (c) Microsoft Corporation.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+
+// This implementation is dedicated to the memory of Mary and Thavatchai.
+
+to_chars_result to_chars(char* __first, char* __last, float __value) {
+  return _Floating_to_chars<_Floating_to_chars_overload::_Plain>(__first, __last, __value, chars_format{}, 0);
+}
+
+to_chars_result to_chars(char* __first, char* __last, double __value) {
+  return _Floating_to_chars<_Floating_to_chars_overload::_Plain>(__first, __last, __value, chars_format{}, 0);
+}
+
+to_chars_result to_chars(char* __first, char* __last, long double __value) {
+  return _Floating_to_chars<_Floating_to_chars_overload::_Plain>(__first, __last, static_cast<double>(__value),
+                                                                 chars_format{}, 0);
+}
+
+to_chars_result to_chars(char* __first, char* __last, float __value, chars_format __fmt) {
+  return _Floating_to_chars<_Floating_to_chars_overload::_Format_only>(__first, __last, __value, __fmt, 0);
+}
+
+to_chars_result to_chars(char* __first, char* __last, double __value, chars_format __fmt) {
+  return _Floating_to_chars<_Floating_to_chars_overload::_Format_only>(__first, __last, __value, __fmt, 0);
+}
+
+to_chars_result to_chars(char* __first, char* __last, long double __value, chars_format __fmt) {
+  return _Floating_to_chars<_Floating_to_chars_overload::_Format_only>(__first, __last, static_cast<double>(__value),
+                                                                       __fmt, 0);
+}
+
+to_chars_result to_chars(char* __first, char* __last, float __value, chars_format __fmt, int __precision) {
+  return _Floating_to_chars<_Floating_to_chars_overload::_Format_precision>(__first, __last, __value, __fmt,
+                                                                            __precision);
+}
+
+to_chars_result to_chars(char* __first, char* __last, double __value, chars_format __fmt, int __precision) {
+  return _Floating_to_chars<_Floating_to_chars_overload::_Format_precision>(__first, __last, __value, __fmt,
+                                                                            __precision);
+}
+
+to_chars_result to_chars(char* __first, char* __last, long double __value, chars_format __fmt, int __precision) {
+  return _Floating_to_chars<_Floating_to_chars_overload::_Format_precision>(
+      __first, __last, static_cast<double>(__value), __fmt, __precision);
+}
+
+_LIBCPP_END_NAMESPACE_STD

third_party/libcxx/src/chrono.cpp

@@ -0,0 +1,254 @@
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#if defined(__MVS__)
+// As part of monotonic clock support on z/OS we need macro _LARGE_TIME_API
+// to be defined before any system header to include definition of struct timespec64.
+#define _LARGE_TIME_API
+#endif
+
+#include <__system_error/system_error.h>
+#include <cerrno> // errno
+#include <chrono>
+
+#if defined(__MVS__)
+#include <__support/ibm/gettod_zos.h> // gettimeofdayMonotonic
+#endif
+
+#include <time.h>        // clock_gettime and CLOCK_{MONOTONIC,REALTIME,MONOTONIC_RAW}
+#include "third_party/libcxx/src/include/apple_availability.h"
+
+#if __has_include(<unistd.h>)
+# include <unistd.h>
+#endif
+
+#if __has_include(<sys/time.h>)
+# include <sys/time.h> // for gettimeofday and timeval
+#endif
+
+#if !defined(__APPLE__) && defined(_POSIX_TIMERS) && _POSIX_TIMERS > 0
+# define _LIBCPP_USE_CLOCK_GETTIME
+#endif
+
+#if defined(_LIBCPP_WIN32API)
+#  define WIN32_LEAN_AND_MEAN
+#  define VC_EXTRA_LEAN
+#  include <windows.h>
+#  if _WIN32_WINNT >= _WIN32_WINNT_WIN8
+#    include <winapifamily.h>
+#  endif
+#endif // defined(_LIBCPP_WIN32API)
+
+#if defined(__Fuchsia__)
+#  include <zircon/syscalls.h>
+#endif
+
+#if __has_include(<mach/mach_time.h>)
+# include <mach/mach_time.h>
+#endif
+
+#if defined(__ELF__) && defined(_LIBCPP_LINK_RT_LIB)
+#  pragma comment(lib, "rt")
+#endif
+
+_LIBCPP_BEGIN_NAMESPACE_STD
+
+namespace chrono
+{
+
+//
+// system_clock
+//
+
+#if defined(_LIBCPP_WIN32API)
+
+#if _WIN32_WINNT < _WIN32_WINNT_WIN8
+
+namespace {
+
+typedef void(WINAPI *GetSystemTimeAsFileTimePtr)(LPFILETIME);
+
+class GetSystemTimeInit {
+public:
+  GetSystemTimeInit() {
+    fp = (GetSystemTimeAsFileTimePtr)GetProcAddress(
+        GetModuleHandleW(L"kernel32.dll"), "GetSystemTimePreciseAsFileTime");
+    if (fp == nullptr)
+      fp = GetSystemTimeAsFileTime;
+  }
+  GetSystemTimeAsFileTimePtr fp;
+};
+
+// Pretend we're inside a system header so the compiler doesn't flag the use of the init_priority
+// attribute with a value that's reserved for the implementation (we're the implementation).
+#include "chrono_system_time_init.h"
+} // namespace
+
+#endif
+
+static system_clock::time_point __libcpp_system_clock_now() {
+  // FILETIME is in 100ns units
+  using filetime_duration =
+      _VSTD::chrono::duration<__int64,
+                              _VSTD::ratio_multiply<_VSTD::ratio<100, 1>,
+                                                    nanoseconds::period>>;
+
+  // The Windows epoch is Jan 1 1601, the Unix epoch Jan 1 1970.
+  static _LIBCPP_CONSTEXPR const seconds nt_to_unix_epoch{11644473600};
+
+  FILETIME ft;
+#if (_WIN32_WINNT >= _WIN32_WINNT_WIN8 && WINAPI_FAMILY_PARTITION(WINAPI_PARTITION_DESKTOP)) || \
+    (_WIN32_WINNT >= _WIN32_WINNT_WIN10)
+  GetSystemTimePreciseAsFileTime(&ft);
+#elif !WINAPI_FAMILY_PARTITION(WINAPI_PARTITION_DESKTOP)
+  GetSystemTimeAsFileTime(&ft);
+#else
+  GetSystemTimeAsFileTimeFunc.fp(&ft);
+#endif
+
+  filetime_duration d{(static_cast<__int64>(ft.dwHighDateTime) << 32) |
+                       static_cast<__int64>(ft.dwLowDateTime)};
+  return system_clock::time_point(duration_cast<system_clock::duration>(d - nt_to_unix_epoch));
+}
+
+#elif defined(CLOCK_REALTIME) && defined(_LIBCPP_USE_CLOCK_GETTIME)
+
+static system_clock::time_point __libcpp_system_clock_now() {
+  struct timespec tp;
+  if (0 != clock_gettime(CLOCK_REALTIME, &tp))
+    __throw_system_error(errno, "clock_gettime(CLOCK_REALTIME) failed");
+  return system_clock::time_point(seconds(tp.tv_sec) + microseconds(tp.tv_nsec / 1000));
+}
+
+#else
+
+static system_clock::time_point __libcpp_system_clock_now() {
+    timeval tv;
+    gettimeofday(&tv, 0);
+    return system_clock::time_point(seconds(tv.tv_sec) + microseconds(tv.tv_usec));
+}
+
+#endif
+
+const bool system_clock::is_steady;
+
+system_clock::time_point
+system_clock::now() noexcept
+{
+    return __libcpp_system_clock_now();
+}
+
+time_t
+system_clock::to_time_t(const time_point& t) noexcept
+{
+    return time_t(duration_cast<seconds>(t.time_since_epoch()).count());
+}
+
+system_clock::time_point
+system_clock::from_time_t(time_t t) noexcept
+{
+    return system_clock::time_point(seconds(t));
+}
+
+//
+// steady_clock
+//
+// Warning:  If this is not truly steady, then it is non-conforming.  It is
+//  better for it to not exist and have the rest of libc++ use system_clock
+//  instead.
+//
+
+#ifndef _LIBCPP_HAS_NO_MONOTONIC_CLOCK
+
+#if defined(__APPLE__)
+
+// On Apple platforms, only CLOCK_UPTIME_RAW, CLOCK_MONOTONIC_RAW or
+// mach_absolute_time are able to time functions in the nanosecond range.
+// Furthermore, only CLOCK_MONOTONIC_RAW is truly monotonic, because it
+// also counts cycles when the system is asleep. Thus, it is the only
+// acceptable implementation of steady_clock.
+static steady_clock::time_point __libcpp_steady_clock_now() {
+    struct timespec tp;
+    if (0 != clock_gettime(CLOCK_MONOTONIC_RAW, &tp))
+        __throw_system_error(errno, "clock_gettime(CLOCK_MONOTONIC_RAW) failed");
+    return steady_clock::time_point(seconds(tp.tv_sec) + nanoseconds(tp.tv_nsec));
+}
+
+#elif defined(_LIBCPP_WIN32API)
+
+// https://msdn.microsoft.com/en-us/library/windows/desktop/ms644905(v=vs.85).aspx says:
+//    If the function fails, the return value is zero. <snip>
+//    On systems that run Windows XP or later, the function will always succeed
+//      and will thus never return zero.
+
+static LARGE_INTEGER
+__QueryPerformanceFrequency()
+{
+    LARGE_INTEGER val;
+    (void) QueryPerformanceFrequency(&val);
+    return val;
+}
+
+static steady_clock::time_point __libcpp_steady_clock_now() {
+  static const LARGE_INTEGER freq = __QueryPerformanceFrequency();
+
+  LARGE_INTEGER counter;
+  (void) QueryPerformanceCounter(&counter);
+  auto seconds = counter.QuadPart / freq.QuadPart;
+  auto fractions = counter.QuadPart % freq.QuadPart;
+  auto dur = seconds * nano::den + fractions * nano::den / freq.QuadPart;
+  return steady_clock::time_point(steady_clock::duration(dur));
+}
+
+#elif defined(__MVS__)
+
+static steady_clock::time_point __libcpp_steady_clock_now() {
+  struct timespec64 ts;
+  if (0 != gettimeofdayMonotonic(&ts))
+    __throw_system_error(errno, "failed to obtain time of day");
+
+  return steady_clock::time_point(seconds(ts.tv_sec) + nanoseconds(ts.tv_nsec));
+}
+
+#  elif defined(__Fuchsia__)
+
+static steady_clock::time_point __libcpp_steady_clock_now() noexcept {
+  // Implicitly link against the vDSO system call ABI without
+  // requiring the final link to specify -lzircon explicitly when
+  // statically linking libc++.
+#    pragma comment(lib, "zircon")
+
+  return steady_clock::time_point(nanoseconds(_zx_clock_get_monotonic()));
+}
+
+#  elif defined(CLOCK_MONOTONIC)
+
+static steady_clock::time_point __libcpp_steady_clock_now() {
+    struct timespec tp;
+    if (0 != clock_gettime(CLOCK_MONOTONIC, &tp))
+        __throw_system_error(errno, "clock_gettime(CLOCK_MONOTONIC) failed");
+    return steady_clock::time_point(seconds(tp.tv_sec) + nanoseconds(tp.tv_nsec));
+}
+
+#  else
+#    error "Monotonic clock not implemented on this platform"
+#  endif
+
+const bool steady_clock::is_steady;
+
+steady_clock::time_point
+steady_clock::now() noexcept
+{
+    return __libcpp_steady_clock_now();
+}
+
+#endif // !_LIBCPP_HAS_NO_MONOTONIC_CLOCK
+
+}
+
+_LIBCPP_END_NAMESPACE_STD

third_party/libcxx/src/chrono_system_time_init.h

@@ -0,0 +1,2 @@
+#pragma GCC system_header
+GetSystemTimeInit GetSystemTimeAsFileTimeFunc _LIBCPP_INIT_PRIORITY_MAX;

third_party/libcxx/src/condition_variable.cpp

@@ -0,0 +1,96 @@
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#include <__config>
+
+#ifndef _LIBCPP_HAS_NO_THREADS
+
+#include <condition_variable>
+#include <thread>
+
+#if defined(__ELF__) && defined(_LIBCPP_LINK_PTHREAD_LIB)
+#  pragma comment(lib, "pthread")
+#endif
+
+_LIBCPP_PUSH_MACROS
+#include <__undef_macros>
+
+_LIBCPP_BEGIN_NAMESPACE_STD
+
+// ~condition_variable is defined elsewhere.
+
+void
+condition_variable::notify_one() noexcept
+{
+    __libcpp_condvar_signal(&__cv_);
+}
+
+void
+condition_variable::notify_all() noexcept
+{
+    __libcpp_condvar_broadcast(&__cv_);
+}
+
+void
+condition_variable::wait(unique_lock<mutex>& lk) noexcept
+{
+    if (!lk.owns_lock())
+        __throw_system_error(EPERM,
+                                  "condition_variable::wait: mutex not locked");
+    int ec = __libcpp_condvar_wait(&__cv_, lk.mutex()->native_handle());
+    if (ec)
+        __throw_system_error(ec, "condition_variable wait failed");
+}
+
+void
+condition_variable::__do_timed_wait(unique_lock<mutex>& lk,
+     chrono::time_point<chrono::system_clock, chrono::nanoseconds> tp) noexcept
+{
+    using namespace chrono;
+    if (!lk.owns_lock())
+        __throw_system_error(EPERM,
+                            "condition_variable::timed wait: mutex not locked");
+    nanoseconds d = tp.time_since_epoch();
+    if (d > nanoseconds(0x59682F000000E941))
+        d = nanoseconds(0x59682F000000E941);
+    __libcpp_timespec_t ts;
+    seconds s = duration_cast<seconds>(d);
+    typedef decltype(ts.tv_sec) ts_sec;
+    _LIBCPP_CONSTEXPR ts_sec ts_sec_max = numeric_limits<ts_sec>::max();
+    if (s.count() < ts_sec_max)
+    {
+        ts.tv_sec = static_cast<ts_sec>(s.count());
+        ts.tv_nsec = static_cast<decltype(ts.tv_nsec)>((d - s).count());
+    }
+    else
+    {
+        ts.tv_sec = ts_sec_max;
+        ts.tv_nsec = giga::num - 1;
+    }
+    int ec = __libcpp_condvar_timedwait(&__cv_, lk.mutex()->native_handle(), &ts);
+    if (ec != 0 && ec != ETIMEDOUT)
+        __throw_system_error(ec, "condition_variable timed_wait failed");
+}
+
+void
+notify_all_at_thread_exit(condition_variable& cond, unique_lock<mutex> lk)
+{
+    auto& tl_ptr = __thread_local_data();
+    // If this thread was not created using std::thread then it will not have
+    // previously allocated.
+    if (tl_ptr.get() == nullptr) {
+        tl_ptr.set_pointer(new __thread_struct);
+    }
+    __thread_local_data()->notify_all_at_thread_exit(&cond, lk.release());
+}
+
+_LIBCPP_END_NAMESPACE_STD
+
+_LIBCPP_POP_MACROS
+
+#endif // !_LIBCPP_HAS_NO_THREADS

third_party/libcxx/src/condition_variable_destructor.cpp

@@ -0,0 +1,46 @@
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+// Define ~condition_variable.
+//
+// On some platforms ~condition_variable has been made trivial and the
+// definition is only provided for ABI compatibility.
+
+#include <__config>
+#include <__threading_support>
+
+#if !defined(_LIBCPP_HAS_NO_THREADS)
+# if _LIBCPP_ABI_VERSION == 1 || !defined(_LIBCPP_HAS_TRIVIAL_CONDVAR_DESTRUCTION)
+#   define NEEDS_CONDVAR_DESTRUCTOR
+# endif
+#endif
+
+_LIBCPP_BEGIN_NAMESPACE_STD
+
+#ifdef NEEDS_CONDVAR_DESTRUCTOR
+
+class _LIBCPP_TYPE_VIS condition_variable
+{
+    __libcpp_condvar_t __cv_ = _LIBCPP_CONDVAR_INITIALIZER;
+public:
+    _LIBCPP_INLINE_VISIBILITY
+    constexpr condition_variable() noexcept = default;
+
+    ~condition_variable();
+
+    condition_variable(const condition_variable&) = delete;
+    condition_variable& operator=(const condition_variable&)  = delete;
+};
+
+condition_variable::~condition_variable()
+{
+    __libcpp_condvar_destroy(&__cv_);
+}
+#endif
+
+_LIBCPP_END_NAMESPACE_STD

third_party/libcxx/src/debug.cpp

@@ -0,0 +1,559 @@
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#include <__assert>
+#include <__config>
+#include <__debug>
+#include <__hash_table>
+#include <algorithm>
+#include <cstdio>
+#include <functional>
+#include <string>
+
+#ifndef _LIBCPP_HAS_NO_THREADS
+#  include <mutex>
+#  if defined(__ELF__) && defined(_LIBCPP_LINK_PTHREAD_LIB)
+#    pragma comment(lib, "pthread")
+#  endif
+#endif
+
+_LIBCPP_BEGIN_NAMESPACE_STD
+
+_LIBCPP_FUNC_VIS
+__libcpp_db*
+__get_db()
+{
+    static _LIBCPP_NO_DESTROY __libcpp_db db;
+    return &db;
+}
+
+_LIBCPP_FUNC_VIS
+const __libcpp_db*
+__get_const_db()
+{
+    return __get_db();
+}
+
+namespace
+{
+
+#ifndef _LIBCPP_HAS_NO_THREADS
+typedef mutex mutex_type;
+typedef lock_guard<mutex_type> WLock;
+typedef lock_guard<mutex_type> RLock;
+
+mutex_type&
+mut()
+{
+    static _LIBCPP_NO_DESTROY mutex_type m;
+    return m;
+}
+#endif // !_LIBCPP_HAS_NO_THREADS
+
+}  // unnamed namespace
+
+__i_node::~__i_node()
+{
+    if (__next_)
+    {
+        __next_->~__i_node();
+        free(__next_);
+    }
+}
+
+__c_node::~__c_node()
+{
+    free(beg_);
+    if (__next_)
+    {
+        __next_->~__c_node();
+        free(__next_);
+    }
+}
+
+__libcpp_db::__libcpp_db()
+    : __cbeg_(nullptr),
+      __cend_(nullptr),
+      __csz_(0),
+      __ibeg_(nullptr),
+      __iend_(nullptr),
+      __isz_(0)
+{
+}
+
+__libcpp_db::~__libcpp_db()
+{
+    if (__cbeg_)
+    {
+        for (__c_node** p = __cbeg_; p != __cend_; ++p)
+        {
+            if (*p != nullptr)
+            {
+                (*p)->~__c_node();
+                free(*p);
+            }
+        }
+        free(__cbeg_);
+    }
+    if (__ibeg_)
+    {
+        for (__i_node** p = __ibeg_; p != __iend_; ++p)
+        {
+            if (*p != nullptr)
+            {
+                (*p)->~__i_node();
+                free(*p);
+            }
+        }
+        free(__ibeg_);
+    }
+}
+
+void*
+__libcpp_db::__find_c_from_i(void* __i) const
+{
+#ifndef _LIBCPP_HAS_NO_THREADS
+    RLock _(mut());
+#endif
+    __i_node* i = __find_iterator(__i);
+    _LIBCPP_ASSERT(i != nullptr, "iterator not found in debug database.");
+    return i->__c_ != nullptr ? i->__c_->__c_ : nullptr;
+}
+
+void
+__libcpp_db::__insert_ic(void* __i, const void* __c)
+{
+#ifndef _LIBCPP_HAS_NO_THREADS
+    WLock _(mut());
+#endif
+    if (__cbeg_ == __cend_)
+        return;
+    size_t hc = hash<const void*>()(__c) % static_cast<size_t>(__cend_ - __cbeg_);
+    __c_node* c = __cbeg_[hc];
+    if (c == nullptr)
+        return;
+    while (c->__c_ != __c)
+    {
+        c = c->__next_;
+        if (c == nullptr)
+            return;
+    }
+    __i_node* i = __insert_iterator(__i);
+    c->__add(i);
+    i->__c_ = c;
+}
+
+void
+__libcpp_db::__insert_c(void* __c, __libcpp_db::_InsertConstruct *__fn)
+{
+#ifndef _LIBCPP_HAS_NO_THREADS
+    WLock _(mut());
+#endif
+    if (__csz_ + 1 > static_cast<size_t>(__cend_ - __cbeg_))
+    {
+        size_t nc = __next_prime(2*static_cast<size_t>(__cend_ - __cbeg_) + 1);
+        __c_node** cbeg = static_cast<__c_node**>(calloc(nc, sizeof(__c_node*)));
+        if (cbeg == nullptr)
+            __throw_bad_alloc();
+
+        for (__c_node** p = __cbeg_; p != __cend_; ++p)
+        {
+            __c_node* q = *p;
+            while (q != nullptr)
+            {
+                size_t h = hash<void*>()(q->__c_) % nc;
+                __c_node* r = q->__next_;
+                q->__next_ = cbeg[h];
+                cbeg[h] = q;
+                q = r;
+            }
+        }
+        free(__cbeg_);
+        __cbeg_ = cbeg;
+        __cend_ = __cbeg_ + nc;
+    }
+    size_t hc = hash<void*>()(__c) % static_cast<size_t>(__cend_ - __cbeg_);
+    __c_node* p = __cbeg_[hc];
+    void *buf = malloc(sizeof(__c_node));
+    if (buf == nullptr)
+      __throw_bad_alloc();
+    __cbeg_[hc] = __fn(buf, __c, p);
+
+    ++__csz_;
+}
+
+void
+__libcpp_db::__erase_i(void* __i)
+{
+#ifndef _LIBCPP_HAS_NO_THREADS
+    WLock _(mut());
+#endif
+    if (__ibeg_ != __iend_)
+    {
+        size_t hi = hash<void*>()(__i) % static_cast<size_t>(__iend_ - __ibeg_);
+        __i_node* p = __ibeg_[hi];
+        if (p != nullptr)
+        {
+            __i_node* q = nullptr;
+            while (p->__i_ != __i)
+            {
+                q = p;
+                p = p->__next_;
+                if (p == nullptr)
+                    return;
+            }
+            if (q == nullptr)
+                __ibeg_[hi] = p->__next_;
+            else
+                q->__next_ = p->__next_;
+            __c_node* c = p->__c_;
+            --__isz_;
+            if (c != nullptr)
+                c->__remove(p);
+            free(p);
+        }
+    }
+}
+
+void
+__libcpp_db::__invalidate_all(void* __c)
+{
+#ifndef _LIBCPP_HAS_NO_THREADS
+    WLock _(mut());
+#endif
+    if (__cend_ != __cbeg_)
+    {
+        size_t hc = hash<void*>()(__c) % static_cast<size_t>(__cend_ - __cbeg_);
+        __c_node* p = __cbeg_[hc];
+        if (p == nullptr)
+            return;
+        while (p->__c_ != __c)
+        {
+            p = p->__next_;
+            if (p == nullptr)
+                return;
+        }
+        while (p->end_ != p->beg_)
+        {
+            --p->end_;
+            (*p->end_)->__c_ = nullptr;
+        }
+    }
+}
+
+__c_node*
+__libcpp_db::__find_c_and_lock(void* __c) const
+{
+#ifndef _LIBCPP_HAS_NO_THREADS
+    mut().lock();
+#endif
+    if (__cend_ == __cbeg_)
+    {
+#ifndef _LIBCPP_HAS_NO_THREADS
+        mut().unlock();
+#endif
+        return nullptr;
+    }
+    size_t hc = hash<void*>()(__c) % static_cast<size_t>(__cend_ - __cbeg_);
+    __c_node* p = __cbeg_[hc];
+    if (p == nullptr)
+    {
+#ifndef _LIBCPP_HAS_NO_THREADS
+        mut().unlock();
+#endif
+        return nullptr;
+    }
+    while (p->__c_ != __c)
+    {
+        p = p->__next_;
+        if (p == nullptr)
+        {
+#ifndef _LIBCPP_HAS_NO_THREADS
+            mut().unlock();
+#endif
+            return nullptr;
+        }
+    }
+    return p;
+}
+
+__c_node*
+__libcpp_db::__find_c(void* __c) const
+{
+    size_t hc = hash<void*>()(__c) % static_cast<size_t>(__cend_ - __cbeg_);
+    __c_node* p = __cbeg_[hc];
+    _LIBCPP_ASSERT(p != nullptr, "debug mode internal logic error __find_c A");
+    while (p->__c_ != __c)
+    {
+        p = p->__next_;
+        _LIBCPP_ASSERT(p != nullptr, "debug mode internal logic error __find_c B");
+    }
+    return p;
+}
+
+void
+__libcpp_db::unlock() const
+{
+#ifndef _LIBCPP_HAS_NO_THREADS
+    mut().unlock();
+#endif
+}
+
+void
+__libcpp_db::__erase_c(void* __c)
+{
+#ifndef _LIBCPP_HAS_NO_THREADS
+    WLock _(mut());
+#endif
+    if (__cend_ != __cbeg_)
+    {
+        size_t hc = hash<void*>()(__c) % static_cast<size_t>(__cend_ - __cbeg_);
+        __c_node* p = __cbeg_[hc];
+        if (p == nullptr)
+            return;
+        __c_node* q = nullptr;
+        _LIBCPP_ASSERT(p != nullptr, "debug mode internal logic error __erase_c A");
+        while (p->__c_ != __c)
+        {
+            q = p;
+            p = p->__next_;
+            if (p == nullptr)
+                return;
+            _LIBCPP_ASSERT(p != nullptr, "debug mode internal logic error __erase_c B");
+        }
+        if (q == nullptr)
+            __cbeg_[hc] = p->__next_;
+        else
+            q->__next_ = p->__next_;
+        while (p->end_ != p->beg_)
+        {
+            --p->end_;
+            (*p->end_)->__c_ = nullptr;
+        }
+        free(p->beg_);
+        free(p);
+        --__csz_;
+    }
+}
+
+void
+__libcpp_db::__iterator_copy(void* __i, const void* __i0)
+{
+#ifndef _LIBCPP_HAS_NO_THREADS
+    WLock _(mut());
+#endif
+    __i_node* i = __find_iterator(__i);
+    __i_node* i0 = __find_iterator(__i0);
+    __c_node* c0 = i0 != nullptr ? i0->__c_ : nullptr;
+    if (i == nullptr && i0 != nullptr)
+        i = __insert_iterator(__i);
+    __c_node* c = i != nullptr ? i->__c_ : nullptr;
+    if (c != c0)
+    {
+        if (c != nullptr)
+            c->__remove(i);
+        if (i != nullptr)
+        {
+            i->__c_ = nullptr;
+            if (c0 != nullptr)
+            {
+                i->__c_ = c0;
+                i->__c_->__add(i);
+            }
+        }
+    }
+}
+
+bool
+__libcpp_db::__dereferenceable(const void* __i) const
+{
+#ifndef _LIBCPP_HAS_NO_THREADS
+    RLock _(mut());
+#endif
+    __i_node* i = __find_iterator(__i);
+    return i != nullptr && i->__c_ != nullptr && i->__c_->__dereferenceable(__i);
+}
+
+bool
+__libcpp_db::__decrementable(const void* __i) const
+{
+#ifndef _LIBCPP_HAS_NO_THREADS
+    RLock _(mut());
+#endif
+    __i_node* i = __find_iterator(__i);
+    return i != nullptr && i->__c_ != nullptr && i->__c_->__decrementable(__i);
+}
+
+bool
+__libcpp_db::__addable(const void* __i, ptrdiff_t __n) const
+{
+#ifndef _LIBCPP_HAS_NO_THREADS
+    RLock _(mut());
+#endif
+    __i_node* i = __find_iterator(__i);
+    return i != nullptr && i->__c_ != nullptr && i->__c_->__addable(__i, __n);
+}
+
+bool
+__libcpp_db::__subscriptable(const void* __i, ptrdiff_t __n) const
+{
+#ifndef _LIBCPP_HAS_NO_THREADS
+    RLock _(mut());
+#endif
+    __i_node* i = __find_iterator(__i);
+    return i != nullptr && i->__c_ != nullptr && i->__c_->__subscriptable(__i, __n);
+}
+
+bool
+__libcpp_db::__less_than_comparable(const void* __i, const void* __j) const
+{
+#ifndef _LIBCPP_HAS_NO_THREADS
+    RLock _(mut());
+#endif
+    __i_node* i = __find_iterator(__i);
+    __i_node* j = __find_iterator(__j);
+    __c_node* ci = i != nullptr ? i->__c_ : nullptr;
+    __c_node* cj = j != nullptr ? j->__c_ : nullptr;
+    return ci == cj;
+}
+
+void
+__libcpp_db::swap(void* c1, void* c2)
+{
+#ifndef _LIBCPP_HAS_NO_THREADS
+    WLock _(mut());
+#endif
+    size_t hc = hash<void*>()(c1) % static_cast<size_t>(__cend_ - __cbeg_);
+    __c_node* p1 = __cbeg_[hc];
+    _LIBCPP_ASSERT(p1 != nullptr, "debug mode internal logic error swap A");
+    while (p1->__c_ != c1)
+    {
+        p1 = p1->__next_;
+        _LIBCPP_ASSERT(p1 != nullptr, "debug mode internal logic error swap B");
+    }
+    hc = hash<void*>()(c2) % static_cast<size_t>(__cend_ - __cbeg_);
+    __c_node* p2 = __cbeg_[hc];
+    _LIBCPP_ASSERT(p2 != nullptr, "debug mode internal logic error swap C");
+    while (p2->__c_ != c2)
+    {
+        p2 = p2->__next_;
+        _LIBCPP_ASSERT(p2 != nullptr, "debug mode internal logic error swap D");
+    }
+    std::swap(p1->beg_, p2->beg_);
+    std::swap(p1->end_, p2->end_);
+    std::swap(p1->cap_, p2->cap_);
+    for (__i_node** p = p1->beg_; p != p1->end_; ++p)
+        (*p)->__c_ = p1;
+    for (__i_node** p = p2->beg_; p != p2->end_; ++p)
+        (*p)->__c_ = p2;
+}
+
+void
+__libcpp_db::__insert_i(void* __i)
+{
+#ifndef _LIBCPP_HAS_NO_THREADS
+    WLock _(mut());
+#endif
+    __insert_iterator(__i);
+}
+
+void
+__c_node::__add(__i_node* i)
+{
+    if (end_ == cap_)
+    {
+        size_t nc = 2*static_cast<size_t>(cap_ - beg_);
+        if (nc == 0)
+            nc = 1;
+        __i_node** beg =
+           static_cast<__i_node**>(malloc(nc * sizeof(__i_node*)));
+        if (beg == nullptr)
+            __throw_bad_alloc();
+
+        if (nc > 1)
+            memcpy(beg, beg_, nc/2*sizeof(__i_node*));
+        free(beg_);
+        beg_ = beg;
+        end_ = beg_ + nc/2;
+        cap_ = beg_ + nc;
+    }
+    *end_++ = i;
+}
+
+// private api
+
+_LIBCPP_HIDDEN
+__i_node*
+__libcpp_db::__insert_iterator(void* __i)
+{
+    if (__isz_ + 1 > static_cast<size_t>(__iend_ - __ibeg_))
+    {
+        size_t nc = __next_prime(2*static_cast<size_t>(__iend_ - __ibeg_) + 1);
+        __i_node** ibeg = static_cast<__i_node**>(calloc(nc, sizeof(__i_node*)));
+        if (ibeg == nullptr)
+            __throw_bad_alloc();
+
+        for (__i_node** p = __ibeg_; p != __iend_; ++p)
+        {
+            __i_node* q = *p;
+            while (q != nullptr)
+            {
+                size_t h = hash<void*>()(q->__i_) % nc;
+                __i_node* r = q->__next_;
+                q->__next_ = ibeg[h];
+                ibeg[h] = q;
+                q = r;
+            }
+        }
+        free(__ibeg_);
+        __ibeg_ = ibeg;
+        __iend_ = __ibeg_ + nc;
+    }
+    size_t hi = hash<void*>()(__i) % static_cast<size_t>(__iend_ - __ibeg_);
+    __i_node* p = __ibeg_[hi];
+    __i_node* r = __ibeg_[hi] =
+      static_cast<__i_node*>(malloc(sizeof(__i_node)));
+    if (r == nullptr)
+        __throw_bad_alloc();
+
+    ::new(r) __i_node(__i, p, nullptr);
+    ++__isz_;
+    return r;
+}
+
+_LIBCPP_HIDDEN
+__i_node*
+__libcpp_db::__find_iterator(const void* __i) const
+{
+    __i_node* r = nullptr;
+    if (__ibeg_ != __iend_)
+    {
+        size_t h = hash<const void*>()(__i) % static_cast<size_t>(__iend_ - __ibeg_);
+        for (__i_node* nd = __ibeg_[h]; nd != nullptr; nd = nd->__next_)
+        {
+            if (nd->__i_ == __i)
+            {
+                r = nd;
+                break;
+            }
+        }
+    }
+    return r;
+}
+
+_LIBCPP_HIDDEN
+void
+__c_node::__remove(__i_node* p)
+{
+    __i_node** r = find(beg_, end_, p);
+    _LIBCPP_ASSERT(r != end_, "debug mode internal logic error __c_node::__remove");
+    if (--end_ != r)
+        memmove(r, r+1, static_cast<size_t>(end_ - r)*sizeof(__i_node*));
+}
+
+_LIBCPP_END_NAMESPACE_STD

third_party/libcxx/src/exception.cpp

@@ -0,0 +1,35 @@
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#include <exception>
+#include <new>
+#include <typeinfo>
+
+#if defined(LIBCXXRT) || defined(LIBCXX_BUILDING_LIBCXXABI)
+  #include <cxxabi.h>
+  using namespace __cxxabiv1;
+  #define HAVE_DEPENDENT_EH_ABI 1
+#endif
+
+#if defined(_LIBCPP_ABI_MICROSOFT)
+#include "third_party/libcxx/src/support/runtime/exception_msvc.ipp"
+#include "third_party/libcxx/src/support/runtime/exception_pointer_msvc.ipp"
+#elif defined(_LIBCPPABI_VERSION)
+#include "third_party/libcxx/src/support/runtime/exception_libcxxabi.ipp"
+#include "third_party/libcxx/src/support/runtime/exception_pointer_cxxabi.ipp"
+#elif defined(LIBCXXRT)
+#include "third_party/libcxx/src/support/runtime/exception_libcxxrt.ipp"
+#include "third_party/libcxx/src/support/runtime/exception_pointer_cxxabi.ipp"
+#elif defined(__GLIBCXX__)
+#include "third_party/libcxx/src/support/runtime/exception_glibcxx.ipp"
+#include "third_party/libcxx/src/support/runtime/exception_pointer_glibcxx.ipp"
+#else
+#include "third_party/libcxx/src/include/atomic_support.h"
+#include "third_party/libcxx/src/support/runtime/exception_fallback.ipp"
+#include "third_party/libcxx/src/support/runtime/exception_pointer_unimplemented.ipp"
+#endif

third_party/libcxx/src/experimental/memory_resource.cpp

@@ -0,0 +1,149 @@
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#include <experimental/memory_resource>
+
+_LIBCPP_SUPPRESS_DEPRECATED_PUSH
+
+#ifndef _LIBCPP_HAS_NO_ATOMIC_HEADER
+#  include <atomic>
+#elif !defined(_LIBCPP_HAS_NO_THREADS)
+#  include <mutex>
+#  if defined(__ELF__) && defined(_LIBCPP_LINK_PTHREAD_LIB)
+#    pragma comment(lib, "pthread")
+#  endif
+#endif
+
+_LIBCPP_BEGIN_NAMESPACE_LFTS_PMR
+
+// memory_resource
+
+//memory_resource::~memory_resource() {}
+
+// new_delete_resource()
+
+class _LIBCPP_TYPE_VIS __new_delete_memory_resource_imp
+    : public memory_resource
+{
+    void *do_allocate(size_t size, size_t align) override {
+#ifdef _LIBCPP_HAS_NO_ALIGNED_ALLOCATION
+        if (__is_overaligned_for_new(align))
+            __throw_bad_alloc();
+#endif
+        return _VSTD::__libcpp_allocate(size, align);
+    }
+
+    void do_deallocate(void *p, size_t n, size_t align) override {
+      _VSTD::__libcpp_deallocate(p, n, align);
+    }
+
+    bool do_is_equal(memory_resource const & other) const noexcept override
+        { return &other == this; }
+
+public:
+    ~__new_delete_memory_resource_imp() override = default;
+};
+
+// null_memory_resource()
+
+class _LIBCPP_TYPE_VIS __null_memory_resource_imp
+    : public memory_resource
+{
+public:
+    ~__null_memory_resource_imp() = default;
+
+protected:
+    virtual void* do_allocate(size_t, size_t) {
+        __throw_bad_alloc();
+    }
+    virtual void do_deallocate(void *, size_t, size_t) {}
+    virtual bool do_is_equal(memory_resource const & __other) const noexcept
+    { return &__other == this; }
+};
+
+namespace {
+
+union ResourceInitHelper {
+  struct {
+    __new_delete_memory_resource_imp new_delete_res;
+    __null_memory_resource_imp       null_res;
+  } resources;
+  char dummy;
+  _LIBCPP_CONSTEXPR_SINCE_CXX14 ResourceInitHelper() : resources() {}
+  ~ResourceInitHelper() {}
+};
+
+// Pretend we're inside a system header so the compiler doesn't flag the use of the init_priority
+// attribute with a value that's reserved for the implementation (we're the implementation).
+#include "memory_resource_init_helper.h"
+
+} // end namespace
+
+
+memory_resource * new_delete_resource() noexcept {
+    return &res_init.resources.new_delete_res;
+}
+
+memory_resource * null_memory_resource() noexcept {
+    return &res_init.resources.null_res;
+}
+
+// default_memory_resource()
+
+static memory_resource *
+__default_memory_resource(bool set = false, memory_resource * new_res = nullptr) noexcept
+{
+#ifndef _LIBCPP_HAS_NO_ATOMIC_HEADER
+    static constinit atomic<memory_resource*> __res{&res_init.resources.new_delete_res};
+    if (set) {
+        new_res = new_res ? new_res : new_delete_resource();
+        // TODO: Can a weaker ordering be used?
+        return _VSTD::atomic_exchange_explicit(
+            &__res, new_res, memory_order_acq_rel);
+    }
+    else {
+        return _VSTD::atomic_load_explicit(
+            &__res, memory_order_acquire);
+    }
+#elif !defined(_LIBCPP_HAS_NO_THREADS)
+    static constinit memory_resource *res = &res_init.resources.new_delete_res;
+    static mutex res_lock;
+    if (set) {
+        new_res = new_res ? new_res : new_delete_resource();
+        lock_guard<mutex> guard(res_lock);
+        memory_resource * old_res = res;
+        res = new_res;
+        return old_res;
+    } else {
+        lock_guard<mutex> guard(res_lock);
+        return res;
+    }
+#else
+    static constinit memory_resource *res = &res_init.resources.new_delete_res;
+    if (set) {
+        new_res = new_res ? new_res : new_delete_resource();
+        memory_resource * old_res = res;
+        res = new_res;
+        return old_res;
+    } else {
+        return res;
+    }
+#endif
+}
+
+memory_resource * get_default_resource() noexcept
+{
+    return __default_memory_resource();
+}
+
+memory_resource * set_default_resource(memory_resource * __new_res) noexcept
+{
+    return __default_memory_resource(true, __new_res);
+}
+
+_LIBCPP_END_NAMESPACE_LFTS_PMR

third_party/libcxx/src/experimental/memory_resource_init_helper.h

@@ -0,0 +1,2 @@
+#pragma GCC system_header
+static constinit ResourceInitHelper res_init _LIBCPP_INIT_PRIORITY_MAX;

third_party/libcxx/src/filesystem/directory_iterator.cpp

@@ -0,0 +1,332 @@
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#include <__assert>
+#include <__config>
+#include <errno.h>
+#include <filesystem>
+#include <stack>
+
+#include "filesystem_common.h"
+
+_LIBCPP_BEGIN_NAMESPACE_FILESYSTEM
+
+using detail::ErrorHandler;
+
+#if defined(_LIBCPP_WIN32API)
+class __dir_stream {
+public:
+  __dir_stream() = delete;
+  __dir_stream& operator=(const __dir_stream&) = delete;
+
+  __dir_stream(__dir_stream&& __ds) noexcept : __stream_(__ds.__stream_),
+                                               __root_(std::move(__ds.__root_)),
+                                               __entry_(std::move(__ds.__entry_)) {
+    __ds.__stream_ = INVALID_HANDLE_VALUE;
+  }
+
+  __dir_stream(const path& root, directory_options opts, error_code& ec)
+      : __stream_(INVALID_HANDLE_VALUE), __root_(root) {
+    if (root.native().empty()) {
+      ec = make_error_code(errc::no_such_file_or_directory);
+      return;
+    }
+    __stream_ = ::FindFirstFileW((root / "*").c_str(), &__data_);
+    if (__stream_ == INVALID_HANDLE_VALUE) {
+      ec = detail::make_windows_error(GetLastError());
+      const bool ignore_permission_denied =
+          bool(opts & directory_options::skip_permission_denied);
+      if (ignore_permission_denied &&
+          ec.value() == static_cast<int>(errc::permission_denied))
+        ec.clear();
+      return;
+    }
+    if (!assign())
+      advance(ec);
+  }
+
+  ~__dir_stream() noexcept {
+    if (__stream_ == INVALID_HANDLE_VALUE)
+      return;
+    close();
+  }
+
+  bool good() const noexcept { return __stream_ != INVALID_HANDLE_VALUE; }
+
+  bool advance(error_code& ec) {
+    while (::FindNextFileW(__stream_, &__data_)) {
+      if (assign())
+        return true;
+    }
+    close();
+    return false;
+  }
+
+  bool assign() {
+    if (!wcscmp(__data_.cFileName, L".") || !wcscmp(__data_.cFileName, L".."))
+      return false;
+    // FIXME: Cache more of this
+    //directory_entry::__cached_data cdata;
+    //cdata.__type_ = get_file_type(__data_);
+    //cdata.__size_ = get_file_size(__data_);
+    //cdata.__write_time_ = get_write_time(__data_);
+    __entry_.__assign_iter_entry(
+        __root_ / __data_.cFileName,
+        directory_entry::__create_iter_result(detail::get_file_type(__data_)));
+    return true;
+  }
+
+private:
+  error_code close() noexcept {
+    error_code ec;
+    if (!::FindClose(__stream_))
+      ec = detail::make_windows_error(GetLastError());
+    __stream_ = INVALID_HANDLE_VALUE;
+    return ec;
+  }
+
+  HANDLE __stream_{INVALID_HANDLE_VALUE};
+  WIN32_FIND_DATAW __data_;
+
+public:
+  path __root_;
+  directory_entry __entry_;
+};
+#else
+class __dir_stream {
+public:
+  __dir_stream() = delete;
+  __dir_stream& operator=(const __dir_stream&) = delete;
+
+  __dir_stream(__dir_stream&& other) noexcept : __stream_(other.__stream_),
+                                                __root_(std::move(other.__root_)),
+                                                __entry_(std::move(other.__entry_)) {
+    other.__stream_ = nullptr;
+  }
+
+  __dir_stream(const path& root, directory_options opts, error_code& ec)
+      : __stream_(nullptr), __root_(root) {
+    if ((__stream_ = ::opendir(root.c_str())) == nullptr) {
+      ec = detail::capture_errno();
+      const bool allow_eacces =
+          bool(opts & directory_options::skip_permission_denied);
+      if (allow_eacces && ec.value() == EACCES)
+        ec.clear();
+      return;
+    }
+    advance(ec);
+  }
+
+  ~__dir_stream() noexcept {
+    if (__stream_)
+      close();
+  }
+
+  bool good() const noexcept { return __stream_ != nullptr; }
+
+  bool advance(error_code& ec) {
+    while (true) {
+      auto str_type_pair = detail::posix_readdir(__stream_, ec);
+      auto& str = str_type_pair.first;
+      if (str == "." || str == "..") {
+        continue;
+      } else if (ec || str.empty()) {
+        close();
+        return false;
+      } else {
+        __entry_.__assign_iter_entry(
+            __root_ / str,
+            directory_entry::__create_iter_result(str_type_pair.second));
+        return true;
+      }
+    }
+  }
+
+private:
+  error_code close() noexcept {
+    error_code m_ec;
+    if (::closedir(__stream_) == -1)
+      m_ec = detail::capture_errno();
+    __stream_ = nullptr;
+    return m_ec;
+  }
+
+  DIR* __stream_{nullptr};
+
+public:
+  path __root_;
+  directory_entry __entry_;
+};
+#endif
+
+// directory_iterator
+
+directory_iterator::directory_iterator(const path& p, error_code* ec,
+                                       directory_options opts) {
+  ErrorHandler<void> err("directory_iterator::directory_iterator(...)", ec, &p);
+
+  error_code m_ec;
+  __imp_ = make_shared<__dir_stream>(p, opts, m_ec);
+  if (ec)
+    *ec = m_ec;
+  if (!__imp_->good()) {
+    __imp_.reset();
+    if (m_ec)
+      err.report(m_ec);
+  }
+}
+
+directory_iterator& directory_iterator::__increment(error_code* ec) {
+  _LIBCPP_ASSERT(__imp_, "Attempting to increment an invalid iterator");
+  ErrorHandler<void> err("directory_iterator::operator++()", ec);
+
+  error_code m_ec;
+  if (!__imp_->advance(m_ec)) {
+    path root = std::move(__imp_->__root_);
+    __imp_.reset();
+    if (m_ec)
+      err.report(m_ec, "at root " PATH_CSTR_FMT, root.c_str());
+  }
+  return *this;
+}
+
+directory_entry const& directory_iterator::__dereference() const {
+  _LIBCPP_ASSERT(__imp_, "Attempting to dereference an invalid iterator");
+  return __imp_->__entry_;
+}
+
+// recursive_directory_iterator
+
+struct recursive_directory_iterator::__shared_imp {
+  stack<__dir_stream> __stack_;
+  directory_options __options_;
+};
+
+recursive_directory_iterator::recursive_directory_iterator(
+    const path& p, directory_options opt, error_code* ec)
+    : __imp_(nullptr), __rec_(true) {
+  ErrorHandler<void> err("recursive_directory_iterator", ec, &p);
+
+  error_code m_ec;
+  __dir_stream new_s(p, opt, m_ec);
+  if (m_ec)
+    err.report(m_ec);
+  if (m_ec || !new_s.good())
+    return;
+
+  __imp_ = make_shared<__shared_imp>();
+  __imp_->__options_ = opt;
+  __imp_->__stack_.push(std::move(new_s));
+}
+
+void recursive_directory_iterator::__pop(error_code* ec) {
+  _LIBCPP_ASSERT(__imp_, "Popping the end iterator");
+  if (ec)
+    ec->clear();
+  __imp_->__stack_.pop();
+  if (__imp_->__stack_.size() == 0)
+    __imp_.reset();
+  else
+    __advance(ec);
+}
+
+directory_options recursive_directory_iterator::options() const {
+  return __imp_->__options_;
+}
+
+int recursive_directory_iterator::depth() const {
+  return __imp_->__stack_.size() - 1;
+}
+
+const directory_entry& recursive_directory_iterator::__dereference() const {
+  return __imp_->__stack_.top().__entry_;
+}
+
+recursive_directory_iterator&
+recursive_directory_iterator::__increment(error_code* ec) {
+  if (ec)
+    ec->clear();
+  if (recursion_pending()) {
+    if (__try_recursion(ec) || (ec && *ec))
+      return *this;
+  }
+  __rec_ = true;
+  __advance(ec);
+  return *this;
+}
+
+void recursive_directory_iterator::__advance(error_code* ec) {
+  ErrorHandler<void> err("recursive_directory_iterator::operator++()", ec);
+
+  const directory_iterator end_it;
+  auto& stack = __imp_->__stack_;
+  error_code m_ec;
+  while (stack.size() > 0) {
+    if (stack.top().advance(m_ec))
+      return;
+    if (m_ec)
+      break;
+    stack.pop();
+  }
+
+  if (m_ec) {
+    path root = std::move(stack.top().__root_);
+    __imp_.reset();
+    err.report(m_ec, "at root " PATH_CSTR_FMT, root.c_str());
+  } else {
+    __imp_.reset();
+  }
+}
+
+bool recursive_directory_iterator::__try_recursion(error_code* ec) {
+  ErrorHandler<void> err("recursive_directory_iterator::operator++()", ec);
+
+  bool rec_sym = bool(options() & directory_options::follow_directory_symlink);
+
+  auto& curr_it = __imp_->__stack_.top();
+
+  bool skip_rec = false;
+  error_code m_ec;
+  if (!rec_sym) {
+    file_status st(curr_it.__entry_.__get_sym_ft(&m_ec));
+    if (m_ec && status_known(st))
+      m_ec.clear();
+    if (m_ec || is_symlink(st) || !is_directory(st))
+      skip_rec = true;
+  } else {
+    file_status st(curr_it.__entry_.__get_ft(&m_ec));
+    if (m_ec && status_known(st))
+      m_ec.clear();
+    if (m_ec || !is_directory(st))
+      skip_rec = true;
+  }
+
+  if (!skip_rec) {
+    __dir_stream new_it(curr_it.__entry_.path(), __imp_->__options_, m_ec);
+    if (new_it.good()) {
+      __imp_->__stack_.push(std::move(new_it));
+      return true;
+    }
+  }
+  if (m_ec) {
+    const bool allow_eacess =
+        bool(__imp_->__options_ & directory_options::skip_permission_denied);
+    if (m_ec.value() == EACCES && allow_eacess) {
+      if (ec)
+        ec->clear();
+    } else {
+      path at_ent = std::move(curr_it.__entry_.__p_);
+      __imp_.reset();
+      err.report(m_ec, "attempting recursion into " PATH_CSTR_FMT,
+                 at_ent.c_str());
+    }
+  }
+  return false;
+}
+
+_LIBCPP_END_NAMESPACE_FILESYSTEM

third_party/libcxx/src/filesystem/filesystem_common.h

@@ -0,0 +1,611 @@
+//===----------------------------------------------------------------------===////
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===////
+
+#ifndef FILESYSTEM_COMMON_H
+#define FILESYSTEM_COMMON_H
+
+#include <__assert>
+#include <__config>
+#include <array>
+#include <cerrno>
+#include <chrono>
+#include <climits>
+#include <cstdarg>
+#include <ctime>
+#include <filesystem>
+#include <ratio>
+#include <utility>
+#include <system_error>
+
+#if defined(_LIBCPP_WIN32API)
+# define WIN32_LEAN_AND_MEAN
+# define NOMINMAX
+# include <windows.h>
+#else
+# include <dirent.h>   // for DIR & friends
+# include <fcntl.h>    /* values for fchmodat */
+# include <sys/stat.h>
+# include <sys/statvfs.h>
+# include <sys/time.h> // for ::utimes as used in __last_write_time
+# include <unistd.h>
+#endif // defined(_LIBCPP_WIN32API)
+
+// We can use the presence of UTIME_OMIT to detect platforms that provide utimensat.
+#if defined(UTIME_OMIT)
+# define _LIBCPP_USE_UTIMENSAT
+#endif
+
+// TODO: Check whether these functions actually need internal linkage, or if they can be made normal header functions
+_LIBCPP_DIAGNOSTIC_PUSH
+_LIBCPP_GCC_DIAGNOSTIC_IGNORED("-Wunused-function")
+_LIBCPP_CLANG_DIAGNOSTIC_IGNORED("-Wunused-function")
+_LIBCPP_CLANG_DIAGNOSTIC_IGNORED("-Wunused-template")
+
+#if defined(_LIBCPP_WIN32API)
+#  define PATHSTR(x) (L##x)
+#  define PATH_CSTR_FMT "\"%ls\""
+#else
+#  define PATHSTR(x) (x)
+#  define PATH_CSTR_FMT "\"%s\""
+#endif
+
+_LIBCPP_BEGIN_NAMESPACE_FILESYSTEM
+
+namespace detail {
+
+#if defined(_LIBCPP_WIN32API)
+// Non anonymous, to allow access from two translation units.
+errc __win_err_to_errc(int err);
+#endif
+
+namespace {
+
+static _LIBCPP_ATTRIBUTE_FORMAT(__printf__, 1, 0) string
+format_string_impl(const char* msg, va_list ap) {
+  array<char, 256> buf;
+
+  va_list apcopy;
+  va_copy(apcopy, ap);
+  int ret = ::vsnprintf(buf.data(), buf.size(), msg, apcopy);
+  va_end(apcopy);
+
+  string result;
+  if (static_cast<size_t>(ret) < buf.size()) {
+    result.assign(buf.data(), static_cast<size_t>(ret));
+  } else {
+    // we did not provide a long enough buffer on our first attempt. The
+    // return value is the number of bytes (excluding the null byte) that are
+    // needed for formatting.
+    size_t size_with_null = static_cast<size_t>(ret) + 1;
+    result.__resize_default_init(size_with_null - 1);
+    ret = ::vsnprintf(&result[0], size_with_null, msg, ap);
+    _LIBCPP_ASSERT(static_cast<size_t>(ret) == (size_with_null - 1), "TODO");
+  }
+  return result;
+}
+
+static _LIBCPP_ATTRIBUTE_FORMAT(__printf__, 1, 2) string
+format_string(const char* msg, ...) {
+  string ret;
+  va_list ap;
+  va_start(ap, msg);
+#ifndef _LIBCPP_HAS_NO_EXCEPTIONS
+  try {
+#endif // _LIBCPP_HAS_NO_EXCEPTIONS
+    ret = format_string_impl(msg, ap);
+#ifndef _LIBCPP_HAS_NO_EXCEPTIONS
+  } catch (...) {
+    va_end(ap);
+    throw;
+  }
+#endif // _LIBCPP_HAS_NO_EXCEPTIONS
+  va_end(ap);
+  return ret;
+}
+
+error_code capture_errno() {
+  _LIBCPP_ASSERT(errno != 0, "Expected errno to be non-zero");
+  return error_code(errno, generic_category());
+}
+
+#if defined(_LIBCPP_WIN32API)
+error_code make_windows_error(int err) {
+  return make_error_code(__win_err_to_errc(err));
+}
+#endif
+
+template <class T>
+T error_value();
+template <>
+_LIBCPP_CONSTEXPR_SINCE_CXX14 void error_value<void>() {}
+template <>
+bool error_value<bool>() {
+  return false;
+}
+#if __SIZEOF_SIZE_T__ != __SIZEOF_LONG_LONG__
+template <>
+size_t error_value<size_t>() {
+  return size_t(-1);
+}
+#endif
+template <>
+uintmax_t error_value<uintmax_t>() {
+  return uintmax_t(-1);
+}
+template <>
+_LIBCPP_CONSTEXPR_SINCE_CXX14 file_time_type error_value<file_time_type>() {
+  return file_time_type::min();
+}
+template <>
+path error_value<path>() {
+  return {};
+}
+
+template <class T>
+struct ErrorHandler {
+  const char* func_name_;
+  error_code* ec_ = nullptr;
+  const path* p1_ = nullptr;
+  const path* p2_ = nullptr;
+
+  ErrorHandler(const char* fname, error_code* ec, const path* p1 = nullptr,
+               const path* p2 = nullptr)
+      : func_name_(fname), ec_(ec), p1_(p1), p2_(p2) {
+    if (ec_)
+      ec_->clear();
+  }
+
+  T report(const error_code& ec) const {
+    if (ec_) {
+      *ec_ = ec;
+      return error_value<T>();
+    }
+    string what = string("in ") + func_name_;
+    switch (bool(p1_) + bool(p2_)) {
+    case 0:
+      __throw_filesystem_error(what, ec);
+    case 1:
+      __throw_filesystem_error(what, *p1_, ec);
+    case 2:
+      __throw_filesystem_error(what, *p1_, *p2_, ec);
+    }
+    __libcpp_unreachable();
+  }
+
+  _LIBCPP_ATTRIBUTE_FORMAT(__printf__, 3, 0)
+  void report_impl(const error_code& ec, const char* msg, va_list ap) const {
+    if (ec_) {
+      *ec_ = ec;
+      return;
+    }
+    string what =
+        string("in ") + func_name_ + ": " + format_string_impl(msg, ap);
+    switch (bool(p1_) + bool(p2_)) {
+    case 0:
+      __throw_filesystem_error(what, ec);
+    case 1:
+      __throw_filesystem_error(what, *p1_, ec);
+    case 2:
+      __throw_filesystem_error(what, *p1_, *p2_, ec);
+    }
+    __libcpp_unreachable();
+  }
+
+  _LIBCPP_ATTRIBUTE_FORMAT(__printf__, 3, 4)
+  T report(const error_code& ec, const char* msg, ...) const {
+    va_list ap;
+    va_start(ap, msg);
+#ifndef _LIBCPP_HAS_NO_EXCEPTIONS
+    try {
+#endif // _LIBCPP_HAS_NO_EXCEPTIONS
+      report_impl(ec, msg, ap);
+#ifndef _LIBCPP_HAS_NO_EXCEPTIONS
+    } catch (...) {
+      va_end(ap);
+      throw;
+    }
+#endif // _LIBCPP_HAS_NO_EXCEPTIONS
+    va_end(ap);
+    return error_value<T>();
+  }
+
+  T report(errc const& err) const {
+    return report(make_error_code(err));
+  }
+
+  _LIBCPP_ATTRIBUTE_FORMAT(__printf__, 3, 4)
+  T report(errc const& err, const char* msg, ...) const {
+    va_list ap;
+    va_start(ap, msg);
+#ifndef _LIBCPP_HAS_NO_EXCEPTIONS
+    try {
+#endif // _LIBCPP_HAS_NO_EXCEPTIONS
+      report_impl(make_error_code(err), msg, ap);
+#ifndef _LIBCPP_HAS_NO_EXCEPTIONS
+    } catch (...) {
+      va_end(ap);
+      throw;
+    }
+#endif // _LIBCPP_HAS_NO_EXCEPTIONS
+    va_end(ap);
+    return error_value<T>();
+  }
+
+private:
+  ErrorHandler(ErrorHandler const&) = delete;
+  ErrorHandler& operator=(ErrorHandler const&) = delete;
+};
+
+using chrono::duration;
+using chrono::duration_cast;
+
+#if defined(_LIBCPP_WIN32API)
+// Various C runtime versions (UCRT, or the legacy msvcrt.dll used by
+// some mingw toolchains) provide different stat function implementations,
+// with a number of limitations with respect to what we want from the
+// stat function. Instead provide our own (in the anonymous detail namespace
+// in posix_compat.h) which does exactly what we want, along with our own
+// stat structure and flag macros.
+
+struct TimeSpec {
+  int64_t tv_sec;
+  int64_t tv_nsec;
+};
+struct StatT {
+  unsigned st_mode;
+  TimeSpec st_atim;
+  TimeSpec st_mtim;
+  uint64_t st_dev; // FILE_ID_INFO::VolumeSerialNumber
+  struct FileIdStruct {
+    unsigned char id[16]; // FILE_ID_INFO::FileId
+    bool operator==(const FileIdStruct &other) const {
+      for (int i = 0; i < 16; i++)
+        if (id[i] != other.id[i])
+          return false;
+      return true;
+    }
+  } st_ino;
+  uint32_t st_nlink;
+  uintmax_t st_size;
+};
+
+#else
+using TimeSpec = struct timespec;
+using TimeVal = struct timeval;
+using StatT = struct stat;
+#endif
+
+template <class FileTimeT, class TimeT,
+          bool IsFloat = is_floating_point<typename FileTimeT::rep>::value>
+struct time_util_base {
+  using rep = typename FileTimeT::rep;
+  using fs_duration = typename FileTimeT::duration;
+  using fs_seconds = duration<rep>;
+  using fs_nanoseconds = duration<rep, nano>;
+  using fs_microseconds = duration<rep, micro>;
+
+  static constexpr rep max_seconds =
+      duration_cast<fs_seconds>(FileTimeT::duration::max()).count();
+
+  static constexpr rep max_nsec =
+      duration_cast<fs_nanoseconds>(FileTimeT::duration::max() -
+                                    fs_seconds(max_seconds))
+          .count();
+
+  static constexpr rep min_seconds =
+      duration_cast<fs_seconds>(FileTimeT::duration::min()).count();
+
+  static constexpr rep min_nsec_timespec =
+      duration_cast<fs_nanoseconds>(
+          (FileTimeT::duration::min() - fs_seconds(min_seconds)) +
+          fs_seconds(1))
+          .count();
+
+private:
+  static _LIBCPP_CONSTEXPR_SINCE_CXX14 fs_duration get_min_nsecs() {
+    return duration_cast<fs_duration>(
+        fs_nanoseconds(min_nsec_timespec) -
+        duration_cast<fs_nanoseconds>(fs_seconds(1)));
+  }
+  // Static assert that these values properly round trip.
+  static_assert(fs_seconds(min_seconds) + get_min_nsecs() ==
+                    FileTimeT::duration::min(),
+                "value doesn't roundtrip");
+
+  static _LIBCPP_CONSTEXPR_SINCE_CXX14 bool check_range() {
+    // This kinda sucks, but it's what happens when we don't have __int128_t.
+    if (sizeof(TimeT) == sizeof(rep)) {
+      typedef duration<long long, ratio<3600 * 24 * 365> > Years;
+      return duration_cast<Years>(fs_seconds(max_seconds)) > Years(250) &&
+             duration_cast<Years>(fs_seconds(min_seconds)) < Years(-250);
+    }
+    return max_seconds >= numeric_limits<TimeT>::max() &&
+           min_seconds <= numeric_limits<TimeT>::min();
+  }
+  static_assert(check_range(), "the representable range is unacceptable small");
+};
+
+template <class FileTimeT, class TimeT>
+struct time_util_base<FileTimeT, TimeT, true> {
+  using rep = typename FileTimeT::rep;
+  using fs_duration = typename FileTimeT::duration;
+  using fs_seconds = duration<rep>;
+  using fs_nanoseconds = duration<rep, nano>;
+  using fs_microseconds = duration<rep, micro>;
+
+  static const rep max_seconds;
+  static const rep max_nsec;
+  static const rep min_seconds;
+  static const rep min_nsec_timespec;
+};
+
+template <class FileTimeT, class TimeT>
+const typename FileTimeT::rep
+    time_util_base<FileTimeT, TimeT, true>::max_seconds =
+        duration_cast<fs_seconds>(FileTimeT::duration::max()).count();
+
+template <class FileTimeT, class TimeT>
+const typename FileTimeT::rep time_util_base<FileTimeT, TimeT, true>::max_nsec =
+    duration_cast<fs_nanoseconds>(FileTimeT::duration::max() -
+                                  fs_seconds(max_seconds))
+        .count();
+
+template <class FileTimeT, class TimeT>
+const typename FileTimeT::rep
+    time_util_base<FileTimeT, TimeT, true>::min_seconds =
+        duration_cast<fs_seconds>(FileTimeT::duration::min()).count();
+
+template <class FileTimeT, class TimeT>
+const typename FileTimeT::rep
+    time_util_base<FileTimeT, TimeT, true>::min_nsec_timespec =
+        duration_cast<fs_nanoseconds>((FileTimeT::duration::min() -
+                                       fs_seconds(min_seconds)) +
+                                      fs_seconds(1))
+            .count();
+
+template <class FileTimeT, class TimeT, class TimeSpecT>
+struct time_util : time_util_base<FileTimeT, TimeT> {
+  using Base = time_util_base<FileTimeT, TimeT>;
+  using Base::max_nsec;
+  using Base::max_seconds;
+  using Base::min_nsec_timespec;
+  using Base::min_seconds;
+
+  using typename Base::fs_duration;
+  using typename Base::fs_microseconds;
+  using typename Base::fs_nanoseconds;
+  using typename Base::fs_seconds;
+
+public:
+  template <class CType, class ChronoType>
+  static _LIBCPP_CONSTEXPR_SINCE_CXX14 bool checked_set(CType* out,
+                                                        ChronoType time) {
+    using Lim = numeric_limits<CType>;
+    if (time > Lim::max() || time < Lim::min())
+      return false;
+    *out = static_cast<CType>(time);
+    return true;
+  }
+
+  static _LIBCPP_CONSTEXPR_SINCE_CXX14 bool is_representable(TimeSpecT tm) {
+    if (tm.tv_sec >= 0) {
+      return tm.tv_sec < max_seconds ||
+             (tm.tv_sec == max_seconds && tm.tv_nsec <= max_nsec);
+    } else if (tm.tv_sec == (min_seconds - 1)) {
+      return tm.tv_nsec >= min_nsec_timespec;
+    } else {
+      return tm.tv_sec >= min_seconds;
+    }
+  }
+
+  static _LIBCPP_CONSTEXPR_SINCE_CXX14 bool is_representable(FileTimeT tm) {
+    auto secs = duration_cast<fs_seconds>(tm.time_since_epoch());
+    auto nsecs = duration_cast<fs_nanoseconds>(tm.time_since_epoch() - secs);
+    if (nsecs.count() < 0) {
+      secs = secs + fs_seconds(1);
+      nsecs = nsecs + fs_seconds(1);
+    }
+    using TLim = numeric_limits<TimeT>;
+    if (secs.count() >= 0)
+      return secs.count() <= TLim::max();
+    return secs.count() >= TLim::min();
+  }
+
+  static _LIBCPP_CONSTEXPR_SINCE_CXX14 FileTimeT
+  convert_from_timespec(TimeSpecT tm) {
+    if (tm.tv_sec >= 0 || tm.tv_nsec == 0) {
+      return FileTimeT(fs_seconds(tm.tv_sec) +
+                       duration_cast<fs_duration>(fs_nanoseconds(tm.tv_nsec)));
+    } else { // tm.tv_sec < 0
+      auto adj_subsec = duration_cast<fs_duration>(fs_seconds(1) -
+                                                   fs_nanoseconds(tm.tv_nsec));
+      auto Dur = fs_seconds(tm.tv_sec + 1) - adj_subsec;
+      return FileTimeT(Dur);
+    }
+  }
+
+  template <class SubSecT>
+  static _LIBCPP_CONSTEXPR_SINCE_CXX14 bool
+  set_times_checked(TimeT* sec_out, SubSecT* subsec_out, FileTimeT tp) {
+    auto dur = tp.time_since_epoch();
+    auto sec_dur = duration_cast<fs_seconds>(dur);
+    auto subsec_dur = duration_cast<fs_nanoseconds>(dur - sec_dur);
+    // The tv_nsec and tv_usec fields must not be negative so adjust accordingly
+    if (subsec_dur.count() < 0) {
+      if (sec_dur.count() > min_seconds) {
+        sec_dur = sec_dur - fs_seconds(1);
+        subsec_dur = subsec_dur + fs_seconds(1);
+      } else {
+        subsec_dur = fs_nanoseconds::zero();
+      }
+    }
+    return checked_set(sec_out, sec_dur.count()) &&
+           checked_set(subsec_out, subsec_dur.count());
+  }
+  static _LIBCPP_CONSTEXPR_SINCE_CXX14 bool convert_to_timespec(TimeSpecT& dest,
+                                                                FileTimeT tp) {
+    if (!is_representable(tp))
+      return false;
+    return set_times_checked(&dest.tv_sec, &dest.tv_nsec, tp);
+  }
+};
+
+#if defined(_LIBCPP_WIN32API)
+using fs_time = time_util<file_time_type, int64_t, TimeSpec>;
+#else
+using fs_time = time_util<file_time_type, time_t, TimeSpec>;
+#endif
+
+#if defined(__APPLE__)
+inline TimeSpec extract_mtime(StatT const& st) { return st.st_mtimespec; }
+inline TimeSpec extract_atime(StatT const& st) { return st.st_atimespec; }
+#elif defined(__MVS__)
+inline TimeSpec extract_mtime(StatT const& st) {
+  TimeSpec TS = {st.st_mtime, 0};
+  return TS;
+}
+inline TimeSpec extract_atime(StatT const& st) {
+  TimeSpec TS = {st.st_atime, 0};
+  return TS;
+}
+#elif defined(_AIX)
+inline TimeSpec extract_mtime(StatT const& st) {
+  TimeSpec TS = {st.st_mtime, st.st_mtime_n};
+  return TS;
+}
+inline TimeSpec extract_atime(StatT const& st) {
+  TimeSpec TS = {st.st_atime, st.st_atime_n};
+  return TS;
+}
+#else
+inline TimeSpec extract_mtime(StatT const& st) { return st.st_mtim; }
+inline TimeSpec extract_atime(StatT const& st) { return st.st_atim; }
+#endif
+
+#if !defined(_LIBCPP_WIN32API)
+inline TimeVal make_timeval(TimeSpec const& ts) {
+  using namespace chrono;
+  auto Convert = [](long nsec) {
+    using int_type = decltype(std::declval<TimeVal>().tv_usec);
+    auto dur = duration_cast<microseconds>(nanoseconds(nsec)).count();
+    return static_cast<int_type>(dur);
+  };
+  TimeVal TV = {};
+  TV.tv_sec = ts.tv_sec;
+  TV.tv_usec = Convert(ts.tv_nsec);
+  return TV;
+}
+
+inline bool posix_utimes(const path& p, std::array<TimeSpec, 2> const& TS,
+                  error_code& ec) {
+  TimeVal ConvertedTS[2] = {make_timeval(TS[0]), make_timeval(TS[1])};
+  if (::utimes(p.c_str(), ConvertedTS) == -1) {
+    ec = capture_errno();
+    return true;
+  }
+  return false;
+}
+
+#if defined(_LIBCPP_USE_UTIMENSAT)
+bool posix_utimensat(const path& p, std::array<TimeSpec, 2> const& TS,
+                     error_code& ec) {
+  if (::utimensat(AT_FDCWD, p.c_str(), TS.data(), 0) == -1) {
+    ec = capture_errno();
+    return true;
+  }
+  return false;
+}
+#endif
+
+bool set_file_times(const path& p, std::array<TimeSpec, 2> const& TS,
+                    error_code& ec) {
+#if !defined(_LIBCPP_USE_UTIMENSAT)
+  return posix_utimes(p, TS, ec);
+#else
+  return posix_utimensat(p, TS, ec);
+#endif
+}
+
+#if defined(DT_BLK)
+template <class DirEntT, class = decltype(DirEntT::d_type)>
+static file_type get_file_type(DirEntT* ent, int) {
+  switch (ent->d_type) {
+  case DT_BLK:
+    return file_type::block;
+  case DT_CHR:
+    return file_type::character;
+  case DT_DIR:
+    return file_type::directory;
+  case DT_FIFO:
+    return file_type::fifo;
+  case DT_LNK:
+    return file_type::symlink;
+  case DT_REG:
+    return file_type::regular;
+  case DT_SOCK:
+    return file_type::socket;
+  // Unlike in lstat, hitting "unknown" here simply means that the underlying
+  // filesystem doesn't support d_type. Report is as 'none' so we correctly
+  // set the cache to empty.
+  case DT_UNKNOWN:
+    break;
+  }
+  return file_type::none;
+}
+#endif // defined(DT_BLK)
+
+template <class DirEntT>
+static file_type get_file_type(DirEntT*, long) {
+  return file_type::none;
+}
+
+static pair<string_view, file_type> posix_readdir(DIR* dir_stream,
+                                                  error_code& ec) {
+  struct dirent* dir_entry_ptr = nullptr;
+  errno = 0; // zero errno in order to detect errors
+  ec.clear();
+  if ((dir_entry_ptr = ::readdir(dir_stream)) == nullptr) {
+    if (errno)
+      ec = capture_errno();
+    return {};
+  } else {
+    return {dir_entry_ptr->d_name, get_file_type(dir_entry_ptr, 0)};
+  }
+}
+
+#else // _LIBCPP_WIN32API
+
+static file_type get_file_type(const WIN32_FIND_DATAW& data) {
+  if (data.dwFileAttributes & FILE_ATTRIBUTE_REPARSE_POINT &&
+      data.dwReserved0 == IO_REPARSE_TAG_SYMLINK)
+    return file_type::symlink;
+  if (data.dwFileAttributes & FILE_ATTRIBUTE_DIRECTORY)
+    return file_type::directory;
+  return file_type::regular;
+}
+static uintmax_t get_file_size(const WIN32_FIND_DATAW& data) {
+  return (static_cast<uint64_t>(data.nFileSizeHigh) << 32) + data.nFileSizeLow;
+}
+static file_time_type get_write_time(const WIN32_FIND_DATAW& data) {
+  ULARGE_INTEGER tmp;
+  const FILETIME& time = data.ftLastWriteTime;
+  tmp.u.LowPart = time.dwLowDateTime;
+  tmp.u.HighPart = time.dwHighDateTime;
+  return file_time_type(file_time_type::duration(tmp.QuadPart));
+}
+
+#endif // !_LIBCPP_WIN32API
+
+} // namespace
+} // end namespace detail
+
+_LIBCPP_END_NAMESPACE_FILESYSTEM
+
+_LIBCPP_DIAGNOSTIC_POP
+
+#endif // FILESYSTEM_COMMON_H

third_party/libcxx/src/filesystem/int128_builtins.cpp

@@ -0,0 +1,54 @@
+/*===-- int128_builtins.cpp - Implement __muloti4 --------------------------===
+ *
+ * Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+ * See https://llvm.org/LICENSE.txt for license information.
+ * SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+ *
+ * ===----------------------------------------------------------------------===
+ *
+ * This file implements __muloti4, and is stolen from the compiler_rt library.
+ *
+ * FIXME: we steal and re-compile it into filesystem, which uses __int128_t,
+ * and requires this builtin when sanitized. See llvm.org/PR30643
+ *
+ * ===----------------------------------------------------------------------===
+ */
+#include <__config>
+#include <climits>
+
+#if !defined(_LIBCPP_HAS_NO_INT128)
+
+extern "C" __attribute__((no_sanitize("undefined"))) _LIBCPP_FUNC_VIS
+__int128_t __muloti4(__int128_t a, __int128_t b, int* overflow) {
+  const int N = (int)(sizeof(__int128_t) * CHAR_BIT);
+  const __int128_t MIN = (__int128_t)1 << (N - 1);
+  const __int128_t MAX = ~MIN;
+  *overflow = 0;
+  __int128_t result = a * b;
+  if (a == MIN) {
+    if (b != 0 && b != 1)
+      *overflow = 1;
+    return result;
+  }
+  if (b == MIN) {
+    if (a != 0 && a != 1)
+      *overflow = 1;
+    return result;
+  }
+  __int128_t sa = a >> (N - 1);
+  __int128_t abs_a = (a ^ sa) - sa;
+  __int128_t sb = b >> (N - 1);
+  __int128_t abs_b = (b ^ sb) - sb;
+  if (abs_a < 2 || abs_b < 2)
+    return result;
+  if (sa == sb) {
+    if (abs_a > MAX / abs_b)
+      *overflow = 1;
+  } else {
+    if (abs_a > MIN / -abs_b)
+      *overflow = 1;
+  }
+  return result;
+}
+
+#endif

third_party/libcxx/src/filesystem/posix_compat.h

@@ -0,0 +1,522 @@
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+//
+// POSIX-like portability helper functions.
+//
+// These generally behave like the proper posix functions, with these
+// exceptions:
+// On Windows, they take paths in wchar_t* form, instead of char* form.
+// The symlink() function is split into two frontends, symlink_file()
+// and symlink_dir().
+//
+// These are provided within an anonymous namespace within the detail
+// namespace - callers need to include this header and call them as
+// detail::function(), regardless of platform.
+//
+
+#ifndef POSIX_COMPAT_H
+#define POSIX_COMPAT_H
+
+#include <__assert>
+#include <filesystem>
+
+#include "filesystem_common.h"
+
+#if defined(_LIBCPP_WIN32API)
+# define WIN32_LEAN_AND_MEAN
+# define NOMINMAX
+# include <windows.h>
+# include <io.h>
+# include <winioctl.h>
+#else
+# include <unistd.h>
+# include <sys/stat.h>
+# include <sys/statvfs.h>
+#endif
+#include <time.h>
+
+#if defined(_LIBCPP_WIN32API)
+// This struct isn't defined in the normal Windows SDK, but only in the
+// Windows Driver Kit.
+struct LIBCPP_REPARSE_DATA_BUFFER {
+  unsigned long  ReparseTag;
+  unsigned short ReparseDataLength;
+  unsigned short Reserved;
+  union {
+    struct {
+      unsigned short SubstituteNameOffset;
+      unsigned short SubstituteNameLength;
+      unsigned short PrintNameOffset;
+      unsigned short PrintNameLength;
+      unsigned long  Flags;
+      wchar_t        PathBuffer[1];
+    } SymbolicLinkReparseBuffer;
+    struct {
+      unsigned short SubstituteNameOffset;
+      unsigned short SubstituteNameLength;
+      unsigned short PrintNameOffset;
+      unsigned short PrintNameLength;
+      wchar_t        PathBuffer[1];
+    } MountPointReparseBuffer;
+    struct {
+      unsigned char DataBuffer[1];
+    } GenericReparseBuffer;
+  };
+};
+#endif
+
+_LIBCPP_BEGIN_NAMESPACE_FILESYSTEM
+
+namespace detail {
+namespace {
+
+#if defined(_LIBCPP_WIN32API)
+
+// Various C runtime header sets provide more or less of these. As we
+// provide our own implementation, undef all potential defines from the
+// C runtime headers and provide a complete set of macros of our own.
+
+#undef _S_IFMT
+#undef _S_IFDIR
+#undef _S_IFCHR
+#undef _S_IFIFO
+#undef _S_IFREG
+#undef _S_IFBLK
+#undef _S_IFLNK
+#undef _S_IFSOCK
+
+#define _S_IFMT   0xF000
+#define _S_IFDIR  0x4000
+#define _S_IFCHR  0x2000
+#define _S_IFIFO  0x1000
+#define _S_IFREG  0x8000
+#define _S_IFBLK  0x6000
+#define _S_IFLNK  0xA000
+#define _S_IFSOCK 0xC000
+
+#undef S_ISDIR
+#undef S_ISFIFO
+#undef S_ISCHR
+#undef S_ISREG
+#undef S_ISLNK
+#undef S_ISBLK
+#undef S_ISSOCK
+
+#define S_ISDIR(m)      (((m) & _S_IFMT) == _S_IFDIR)
+#define S_ISCHR(m)      (((m) & _S_IFMT) == _S_IFCHR)
+#define S_ISFIFO(m)     (((m) & _S_IFMT) == _S_IFIFO)
+#define S_ISREG(m)      (((m) & _S_IFMT) == _S_IFREG)
+#define S_ISBLK(m)      (((m) & _S_IFMT) == _S_IFBLK)
+#define S_ISLNK(m)      (((m) & _S_IFMT) == _S_IFLNK)
+#define S_ISSOCK(m)     (((m) & _S_IFMT) == _S_IFSOCK)
+
+#define O_NONBLOCK 0
+
+
+// There were 369 years and 89 leap days from the Windows epoch
+// (1601) to the Unix epoch (1970).
+#define FILE_TIME_OFFSET_SECS (uint64_t(369 * 365 + 89) * (24 * 60 * 60))
+
+TimeSpec filetime_to_timespec(LARGE_INTEGER li) {
+  TimeSpec ret;
+  ret.tv_sec = li.QuadPart / 10000000 - FILE_TIME_OFFSET_SECS;
+  ret.tv_nsec = (li.QuadPart % 10000000) * 100;
+  return ret;
+}
+
+TimeSpec filetime_to_timespec(FILETIME ft) {
+  LARGE_INTEGER li;
+  li.LowPart = ft.dwLowDateTime;
+  li.HighPart = ft.dwHighDateTime;
+  return filetime_to_timespec(li);
+}
+
+FILETIME timespec_to_filetime(TimeSpec ts) {
+  LARGE_INTEGER li;
+  li.QuadPart =
+      ts.tv_nsec / 100 + (ts.tv_sec + FILE_TIME_OFFSET_SECS) * 10000000;
+  FILETIME ft;
+  ft.dwLowDateTime = li.LowPart;
+  ft.dwHighDateTime = li.HighPart;
+  return ft;
+}
+
+int set_errno(int e = GetLastError()) {
+  errno = static_cast<int>(__win_err_to_errc(e));
+  return -1;
+}
+
+class WinHandle {
+public:
+  WinHandle(const wchar_t *p, DWORD access, DWORD flags) {
+    h = CreateFileW(
+        p, access, FILE_SHARE_READ | FILE_SHARE_WRITE | FILE_SHARE_DELETE,
+        nullptr, OPEN_EXISTING, FILE_FLAG_BACKUP_SEMANTICS | flags, nullptr);
+  }
+  ~WinHandle() {
+    if (h != INVALID_HANDLE_VALUE)
+      CloseHandle(h);
+  }
+  operator HANDLE() const { return h; }
+  operator bool() const { return h != INVALID_HANDLE_VALUE; }
+
+private:
+  HANDLE h;
+};
+
+int stat_handle(HANDLE h, StatT *buf) {
+  FILE_BASIC_INFO basic;
+  if (!GetFileInformationByHandleEx(h, FileBasicInfo, &basic, sizeof(basic)))
+    return set_errno();
+  memset(buf, 0, sizeof(*buf));
+  buf->st_mtim = filetime_to_timespec(basic.LastWriteTime);
+  buf->st_atim = filetime_to_timespec(basic.LastAccessTime);
+  buf->st_mode = 0555; // Read-only
+  if (!(basic.FileAttributes & FILE_ATTRIBUTE_READONLY))
+    buf->st_mode |= 0222; // Write
+  if (basic.FileAttributes & FILE_ATTRIBUTE_DIRECTORY) {
+    buf->st_mode |= _S_IFDIR;
+  } else {
+    buf->st_mode |= _S_IFREG;
+  }
+  if (basic.FileAttributes & FILE_ATTRIBUTE_REPARSE_POINT) {
+    FILE_ATTRIBUTE_TAG_INFO tag;
+    if (!GetFileInformationByHandleEx(h, FileAttributeTagInfo, &tag,
+                                      sizeof(tag)))
+      return set_errno();
+    if (tag.ReparseTag == IO_REPARSE_TAG_SYMLINK)
+      buf->st_mode = (buf->st_mode & ~_S_IFMT) | _S_IFLNK;
+  }
+  FILE_STANDARD_INFO standard;
+  if (!GetFileInformationByHandleEx(h, FileStandardInfo, &standard,
+                                    sizeof(standard)))
+    return set_errno();
+  buf->st_nlink = standard.NumberOfLinks;
+  buf->st_size = standard.EndOfFile.QuadPart;
+  BY_HANDLE_FILE_INFORMATION info;
+  if (!GetFileInformationByHandle(h, &info))
+    return set_errno();
+  buf->st_dev = info.dwVolumeSerialNumber;
+  memcpy(&buf->st_ino.id[0], &info.nFileIndexHigh, 4);
+  memcpy(&buf->st_ino.id[4], &info.nFileIndexLow, 4);
+  return 0;
+}
+
+int stat_file(const wchar_t *path, StatT *buf, DWORD flags) {
+  WinHandle h(path, FILE_READ_ATTRIBUTES, flags);
+  if (!h)
+    return set_errno();
+  int ret = stat_handle(h, buf);
+  return ret;
+}
+
+int stat(const wchar_t *path, StatT *buf) { return stat_file(path, buf, 0); }
+
+int lstat(const wchar_t *path, StatT *buf) {
+  return stat_file(path, buf, FILE_FLAG_OPEN_REPARSE_POINT);
+}
+
+int fstat(int fd, StatT *buf) {
+  HANDLE h = reinterpret_cast<HANDLE>(_get_osfhandle(fd));
+  return stat_handle(h, buf);
+}
+
+int mkdir(const wchar_t *path, int permissions) {
+  (void)permissions;
+  return _wmkdir(path);
+}
+
+int symlink_file_dir(const wchar_t *oldname, const wchar_t *newname,
+                     bool is_dir) {
+  path dest(oldname);
+  dest.make_preferred();
+  oldname = dest.c_str();
+  DWORD flags = is_dir ? SYMBOLIC_LINK_FLAG_DIRECTORY : 0;
+  if (CreateSymbolicLinkW(newname, oldname,
+                          flags | SYMBOLIC_LINK_FLAG_ALLOW_UNPRIVILEGED_CREATE))
+    return 0;
+  int e = GetLastError();
+  if (e != ERROR_INVALID_PARAMETER)
+    return set_errno(e);
+  if (CreateSymbolicLinkW(newname, oldname, flags))
+    return 0;
+  return set_errno();
+}
+
+int symlink_file(const wchar_t *oldname, const wchar_t *newname) {
+  return symlink_file_dir(oldname, newname, false);
+}
+
+int symlink_dir(const wchar_t *oldname, const wchar_t *newname) {
+  return symlink_file_dir(oldname, newname, true);
+}
+
+int link(const wchar_t *oldname, const wchar_t *newname) {
+  if (CreateHardLinkW(newname, oldname, nullptr))
+    return 0;
+  return set_errno();
+}
+
+int remove(const wchar_t *path) {
+  detail::WinHandle h(path, DELETE, FILE_FLAG_OPEN_REPARSE_POINT);
+  if (!h)
+    return set_errno();
+  FILE_DISPOSITION_INFO info;
+  info.DeleteFile = TRUE;
+  if (!SetFileInformationByHandle(h, FileDispositionInfo, &info, sizeof(info)))
+    return set_errno();
+  return 0;
+}
+
+int truncate_handle(HANDLE h, off_t length) {
+  LARGE_INTEGER size_param;
+  size_param.QuadPart = length;
+  if (!SetFilePointerEx(h, size_param, 0, FILE_BEGIN))
+    return set_errno();
+  if (!SetEndOfFile(h))
+    return set_errno();
+  return 0;
+}
+
+int ftruncate(int fd, off_t length) {
+  HANDLE h = reinterpret_cast<HANDLE>(_get_osfhandle(fd));
+  return truncate_handle(h, length);
+}
+
+int truncate(const wchar_t *path, off_t length) {
+  detail::WinHandle h(path, GENERIC_WRITE, 0);
+  if (!h)
+    return set_errno();
+  return truncate_handle(h, length);
+}
+
+int rename(const wchar_t *from, const wchar_t *to) {
+  if (!(MoveFileExW(from, to,
+                    MOVEFILE_COPY_ALLOWED | MOVEFILE_REPLACE_EXISTING |
+                        MOVEFILE_WRITE_THROUGH)))
+    return set_errno();
+  return 0;
+}
+
+template <class... Args> int open(const wchar_t *filename, Args... args) {
+  return _wopen(filename, args...);
+}
+int close(int fd) { return _close(fd); }
+int chdir(const wchar_t *path) { return _wchdir(path); }
+
+struct StatVFS {
+  uint64_t f_frsize;
+  uint64_t f_blocks;
+  uint64_t f_bfree;
+  uint64_t f_bavail;
+};
+
+int statvfs(const wchar_t *p, StatVFS *buf) {
+  path dir = p;
+  while (true) {
+    error_code local_ec;
+    const file_status st = status(dir, local_ec);
+    if (!exists(st) || is_directory(st))
+      break;
+    path parent = dir.parent_path();
+    if (parent == dir) {
+      errno = ENOENT;
+      return -1;
+    }
+    dir = parent;
+  }
+  ULARGE_INTEGER free_bytes_available_to_caller, total_number_of_bytes,
+      total_number_of_free_bytes;
+  if (!GetDiskFreeSpaceExW(dir.c_str(), &free_bytes_available_to_caller,
+                           &total_number_of_bytes, &total_number_of_free_bytes))
+    return set_errno();
+  buf->f_frsize = 1;
+  buf->f_blocks = total_number_of_bytes.QuadPart;
+  buf->f_bfree = total_number_of_free_bytes.QuadPart;
+  buf->f_bavail = free_bytes_available_to_caller.QuadPart;
+  return 0;
+}
+
+wchar_t *getcwd(wchar_t *buff, size_t size) { return _wgetcwd(buff, size); }
+
+wchar_t *realpath(const wchar_t *path, wchar_t *resolved_name) {
+  // Only expected to be used with us allocating the buffer.
+  _LIBCPP_ASSERT(resolved_name == nullptr,
+                 "Windows realpath() assumes a null resolved_name");
+
+  WinHandle h(path, FILE_READ_ATTRIBUTES, 0);
+  if (!h) {
+    set_errno();
+    return nullptr;
+  }
+  size_t buff_size = MAX_PATH + 10;
+  std::unique_ptr<wchar_t, decltype(&::free)> buff(
+      static_cast<wchar_t *>(malloc(buff_size * sizeof(wchar_t))), &::free);
+  DWORD retval = GetFinalPathNameByHandleW(
+      h, buff.get(), buff_size, FILE_NAME_NORMALIZED | VOLUME_NAME_DOS);
+  if (retval > buff_size) {
+    buff_size = retval;
+    buff.reset(static_cast<wchar_t *>(malloc(buff_size * sizeof(wchar_t))));
+    retval = GetFinalPathNameByHandleW(h, buff.get(), buff_size,
+                                       FILE_NAME_NORMALIZED | VOLUME_NAME_DOS);
+  }
+  if (!retval) {
+    set_errno();
+    return nullptr;
+  }
+  wchar_t *ptr = buff.get();
+  if (!wcsncmp(ptr, L"\\\\?\\", 4)) {
+    if (ptr[5] == ':') { // \\?\X: -> X:
+      memmove(&ptr[0], &ptr[4], (wcslen(&ptr[4]) + 1) * sizeof(wchar_t));
+    } else if (!wcsncmp(&ptr[4], L"UNC\\", 4)) { // \\?\UNC\server -> \\server
+      wcscpy(&ptr[0], L"\\\\");
+      memmove(&ptr[2], &ptr[8], (wcslen(&ptr[8]) + 1) * sizeof(wchar_t));
+    }
+  }
+  return buff.release();
+}
+
+#define AT_FDCWD -1
+#define AT_SYMLINK_NOFOLLOW 1
+using ModeT = int;
+
+int fchmod_handle(HANDLE h, int perms) {
+  FILE_BASIC_INFO basic;
+  if (!GetFileInformationByHandleEx(h, FileBasicInfo, &basic, sizeof(basic)))
+    return set_errno();
+  DWORD orig_attributes = basic.FileAttributes;
+  basic.FileAttributes &= ~FILE_ATTRIBUTE_READONLY;
+  if ((perms & 0222) == 0)
+    basic.FileAttributes |= FILE_ATTRIBUTE_READONLY;
+  if (basic.FileAttributes != orig_attributes &&
+      !SetFileInformationByHandle(h, FileBasicInfo, &basic, sizeof(basic)))
+    return set_errno();
+  return 0;
+}
+
+int fchmodat(int fd, const wchar_t *path, int perms, int flag) {
+  DWORD attributes = GetFileAttributesW(path);
+  if (attributes == INVALID_FILE_ATTRIBUTES)
+    return set_errno();
+  if (attributes & FILE_ATTRIBUTE_REPARSE_POINT &&
+      !(flag & AT_SYMLINK_NOFOLLOW)) {
+    // If the file is a symlink, and we are supposed to operate on the target
+    // of the symlink, we need to open a handle to it, without the
+    // FILE_FLAG_OPEN_REPARSE_POINT flag, to open the destination of the
+    // symlink, and operate on it via the handle.
+    detail::WinHandle h(path, FILE_READ_ATTRIBUTES | FILE_WRITE_ATTRIBUTES, 0);
+    if (!h)
+      return set_errno();
+    return fchmod_handle(h, perms);
+  } else {
+    // For a non-symlink, or if operating on the symlink itself instead of
+    // its target, we can use SetFileAttributesW, saving a few calls.
+    DWORD orig_attributes = attributes;
+    attributes &= ~FILE_ATTRIBUTE_READONLY;
+    if ((perms & 0222) == 0)
+      attributes |= FILE_ATTRIBUTE_READONLY;
+    if (attributes != orig_attributes && !SetFileAttributesW(path, attributes))
+      return set_errno();
+  }
+  return 0;
+}
+
+int fchmod(int fd, int perms) {
+  HANDLE h = reinterpret_cast<HANDLE>(_get_osfhandle(fd));
+  return fchmod_handle(h, perms);
+}
+
+#define MAX_SYMLINK_SIZE MAXIMUM_REPARSE_DATA_BUFFER_SIZE
+using SSizeT = ::int64_t;
+
+SSizeT readlink(const wchar_t *path, wchar_t *ret_buf, size_t bufsize) {
+  uint8_t buf[MAXIMUM_REPARSE_DATA_BUFFER_SIZE];
+  detail::WinHandle h(path, FILE_READ_ATTRIBUTES, FILE_FLAG_OPEN_REPARSE_POINT);
+  if (!h)
+    return set_errno();
+  DWORD out;
+  if (!DeviceIoControl(h, FSCTL_GET_REPARSE_POINT, nullptr, 0, buf, sizeof(buf),
+                       &out, 0))
+    return set_errno();
+  const auto *reparse = reinterpret_cast<LIBCPP_REPARSE_DATA_BUFFER *>(buf);
+  size_t path_buf_offset = offsetof(LIBCPP_REPARSE_DATA_BUFFER,
+                                    SymbolicLinkReparseBuffer.PathBuffer[0]);
+  if (out < path_buf_offset) {
+    errno = EINVAL;
+    return -1;
+  }
+  if (reparse->ReparseTag != IO_REPARSE_TAG_SYMLINK) {
+    errno = EINVAL;
+    return -1;
+  }
+  const auto &symlink = reparse->SymbolicLinkReparseBuffer;
+  unsigned short name_offset, name_length;
+  if (symlink.PrintNameLength == 0) {
+    name_offset = symlink.SubstituteNameOffset;
+    name_length = symlink.SubstituteNameLength;
+  } else {
+    name_offset = symlink.PrintNameOffset;
+    name_length = symlink.PrintNameLength;
+  }
+  // name_offset/length are expressed in bytes, not in wchar_t
+  if (path_buf_offset + name_offset + name_length > out) {
+    errno = EINVAL;
+    return -1;
+  }
+  if (name_length / sizeof(wchar_t) > bufsize) {
+    errno = ENOMEM;
+    return -1;
+  }
+  memcpy(ret_buf, &symlink.PathBuffer[name_offset / sizeof(wchar_t)],
+         name_length);
+  return name_length / sizeof(wchar_t);
+}
+
+#else
+int symlink_file(const char *oldname, const char *newname) {
+  return ::symlink(oldname, newname);
+}
+int symlink_dir(const char *oldname, const char *newname) {
+  return ::symlink(oldname, newname);
+}
+using ::chdir;
+using ::close;
+using ::fchmod;
+#if defined(AT_SYMLINK_NOFOLLOW) && defined(AT_FDCWD)
+using ::fchmodat;
+#endif
+using ::fstat;
+using ::ftruncate;
+using ::getcwd;
+using ::link;
+using ::lstat;
+using ::mkdir;
+using ::open;
+using ::readlink;
+using ::realpath;
+using ::remove;
+using ::rename;
+using ::stat;
+using ::statvfs;
+using ::truncate;
+
+#define O_BINARY 0
+
+using StatVFS = struct statvfs;
+using ModeT = ::mode_t;
+using SSizeT = ::ssize_t;
+
+#endif
+
+} // namespace
+} // end namespace detail
+
+_LIBCPP_END_NAMESPACE_FILESYSTEM
+
+#endif // POSIX_COMPAT_H

third_party/libcxx/src/functional.cpp

@@ -0,0 +1,27 @@
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#include <functional>
+
+_LIBCPP_BEGIN_NAMESPACE_STD
+
+#ifdef _LIBCPP_ABI_BAD_FUNCTION_CALL_KEY_FUNCTION
+bad_function_call::~bad_function_call() noexcept
+{
+}
+#endif
+
+#ifdef _LIBCPP_ABI_BAD_FUNCTION_CALL_GOOD_WHAT_MESSAGE
+const char*
+bad_function_call::what() const noexcept
+{
+    return "std::bad_function_call";
+}
+#endif
+
+_LIBCPP_END_NAMESPACE_STD

third_party/libcxx/src/future.cpp

@@ -0,0 +1,269 @@
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#include <__config>
+
+#ifndef _LIBCPP_HAS_NO_THREADS
+
+#include <future>
+#include <string>
+
+_LIBCPP_BEGIN_NAMESPACE_STD
+
+class _LIBCPP_HIDDEN __future_error_category
+    : public __do_message
+{
+public:
+    virtual const char* name() const noexcept;
+    virtual string message(int ev) const;
+};
+
+const char*
+__future_error_category::name() const noexcept
+{
+    return "future";
+}
+
+_LIBCPP_DIAGNOSTIC_PUSH
+_LIBCPP_CLANG_DIAGNOSTIC_IGNORED("-Wswitch")
+_LIBCPP_GCC_DIAGNOSTIC_IGNORED("-Wswitch")
+
+string
+__future_error_category::message(int ev) const
+{
+    switch (static_cast<future_errc>(ev))
+    {
+    case future_errc(0):  // For backwards compatibility with C++11 (LWG 2056)
+    case future_errc::broken_promise:
+        return string("The associated promise has been destructed prior "
+                      "to the associated state becoming ready.");
+    case future_errc::future_already_retrieved:
+        return string("The future has already been retrieved from "
+                      "the promise or packaged_task.");
+    case future_errc::promise_already_satisfied:
+        return string("The state of the promise has already been set.");
+    case future_errc::no_state:
+        return string("Operation not permitted on an object without "
+                      "an associated state.");
+    }
+    return string("unspecified future_errc value\n");
+}
+
+_LIBCPP_DIAGNOSTIC_POP
+
+const error_category&
+future_category() noexcept
+{
+    static __future_error_category __f;
+    return __f;
+}
+
+future_error::future_error(error_code __ec)
+    : logic_error(__ec.message()),
+      __ec_(__ec)
+{
+}
+
+future_error::~future_error() noexcept
+{
+}
+
+void
+__assoc_sub_state::__on_zero_shared() noexcept
+{
+    delete this;
+}
+
+void
+__assoc_sub_state::set_value()
+{
+    unique_lock<mutex> __lk(__mut_);
+    if (__has_value())
+        __throw_future_error(future_errc::promise_already_satisfied);
+    __state_ |= __constructed | ready;
+    __cv_.notify_all();
+}
+
+void
+__assoc_sub_state::set_value_at_thread_exit()
+{
+    unique_lock<mutex> __lk(__mut_);
+    if (__has_value())
+        __throw_future_error(future_errc::promise_already_satisfied);
+    __state_ |= __constructed;
+    __thread_local_data()->__make_ready_at_thread_exit(this);
+}
+
+void
+__assoc_sub_state::set_exception(exception_ptr __p)
+{
+    unique_lock<mutex> __lk(__mut_);
+    if (__has_value())
+        __throw_future_error(future_errc::promise_already_satisfied);
+    __exception_ = __p;
+    __state_ |= ready;
+    __cv_.notify_all();
+}
+
+void
+__assoc_sub_state::set_exception_at_thread_exit(exception_ptr __p)
+{
+    unique_lock<mutex> __lk(__mut_);
+    if (__has_value())
+        __throw_future_error(future_errc::promise_already_satisfied);
+    __exception_ = __p;
+    __thread_local_data()->__make_ready_at_thread_exit(this);
+}
+
+void
+__assoc_sub_state::__make_ready()
+{
+    unique_lock<mutex> __lk(__mut_);
+    __state_ |= ready;
+    __cv_.notify_all();
+}
+
+void
+__assoc_sub_state::copy()
+{
+    unique_lock<mutex> __lk(__mut_);
+    __sub_wait(__lk);
+    if (__exception_ != nullptr)
+        rethrow_exception(__exception_);
+}
+
+void
+__assoc_sub_state::wait()
+{
+    unique_lock<mutex> __lk(__mut_);
+    __sub_wait(__lk);
+}
+
+void
+__assoc_sub_state::__sub_wait(unique_lock<mutex>& __lk)
+{
+    if (!__is_ready())
+    {
+        if (__state_ & static_cast<unsigned>(deferred))
+        {
+            __state_ &= ~static_cast<unsigned>(deferred);
+            __lk.unlock();
+            __execute();
+        }
+        else
+            while (!__is_ready())
+                __cv_.wait(__lk);
+    }
+}
+
+void
+__assoc_sub_state::__execute()
+{
+    __throw_future_error(future_errc::no_state);
+}
+
+future<void>::future(__assoc_sub_state* __state)
+    : __state_(__state)
+{
+    __state_->__attach_future();
+}
+
+future<void>::~future()
+{
+    if (__state_)
+        __state_->__release_shared();
+}
+
+void
+future<void>::get()
+{
+    unique_ptr<__shared_count, __release_shared_count> __(__state_);
+    __assoc_sub_state* __s = __state_;
+    __state_ = nullptr;
+    __s->copy();
+}
+
+promise<void>::promise()
+    : __state_(new __assoc_sub_state)
+{
+}
+
+promise<void>::~promise()
+{
+    if (__state_)
+    {
+#ifndef _LIBCPP_HAS_NO_EXCEPTIONS
+        if (!__state_->__has_value() && __state_->use_count() > 1)
+            __state_->set_exception(make_exception_ptr(
+                      future_error(make_error_code(future_errc::broken_promise))
+                                                      ));
+#endif // _LIBCPP_HAS_NO_EXCEPTIONS
+        __state_->__release_shared();
+    }
+}
+
+future<void>
+promise<void>::get_future()
+{
+    if (__state_ == nullptr)
+        __throw_future_error(future_errc::no_state);
+    return future<void>(__state_);
+}
+
+void
+promise<void>::set_value()
+{
+    if (__state_ == nullptr)
+        __throw_future_error(future_errc::no_state);
+    __state_->set_value();
+}
+
+void
+promise<void>::set_exception(exception_ptr __p)
+{
+    if (__state_ == nullptr)
+        __throw_future_error(future_errc::no_state);
+    __state_->set_exception(__p);
+}
+
+void
+promise<void>::set_value_at_thread_exit()
+{
+    if (__state_ == nullptr)
+        __throw_future_error(future_errc::no_state);
+    __state_->set_value_at_thread_exit();
+}
+
+void
+promise<void>::set_exception_at_thread_exit(exception_ptr __p)
+{
+    if (__state_ == nullptr)
+        __throw_future_error(future_errc::no_state);
+    __state_->set_exception_at_thread_exit(__p);
+}
+
+shared_future<void>::~shared_future()
+{
+    if (__state_)
+        __state_->__release_shared();
+}
+
+shared_future<void>&
+shared_future<void>::operator=(const shared_future& __rhs)
+{
+    if (__rhs.__state_)
+        __rhs.__state_->__add_shared();
+    if (__state_)
+        __state_->__release_shared();
+    __state_ = __rhs.__state_;
+    return *this;
+}
+
+_LIBCPP_END_NAMESPACE_STD
+
+#endif // !_LIBCPP_HAS_NO_THREADS

third_party/libcxx/src/hash.cpp

@@ -0,0 +1,559 @@
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#include <__hash_table>
+#include <algorithm>
+#include <stdexcept>
+#include <type_traits>
+
+_LIBCPP_CLANG_DIAGNOSTIC_IGNORED("-Wtautological-constant-out-of-range-compare")
+
+_LIBCPP_BEGIN_NAMESPACE_STD
+
+namespace {
+
+// handle all next_prime(i) for i in [1, 210), special case 0
+const unsigned small_primes[] =
+{
+    0,
+    2,
+    3,
+    5,
+    7,
+    11,
+    13,
+    17,
+    19,
+    23,
+    29,
+    31,
+    37,
+    41,
+    43,
+    47,
+    53,
+    59,
+    61,
+    67,
+    71,
+    73,
+    79,
+    83,
+    89,
+    97,
+    101,
+    103,
+    107,
+    109,
+    113,
+    127,
+    131,
+    137,
+    139,
+    149,
+    151,
+    157,
+    163,
+    167,
+    173,
+    179,
+    181,
+    191,
+    193,
+    197,
+    199,
+    211
+};
+
+// potential primes = 210*k + indices[i], k >= 1
+//   these numbers are not divisible by 2, 3, 5 or 7
+//   (or any integer 2 <= j <= 10 for that matter).
+const unsigned indices[] =
+{
+    1,
+    11,
+    13,
+    17,
+    19,
+    23,
+    29,
+    31,
+    37,
+    41,
+    43,
+    47,
+    53,
+    59,
+    61,
+    67,
+    71,
+    73,
+    79,
+    83,
+    89,
+    97,
+    101,
+    103,
+    107,
+    109,
+    113,
+    121,
+    127,
+    131,
+    137,
+    139,
+    143,
+    149,
+    151,
+    157,
+    163,
+    167,
+    169,
+    173,
+    179,
+    181,
+    187,
+    191,
+    193,
+    197,
+    199,
+    209
+};
+
+}
+
+// Returns:  If n == 0, returns 0.  Else returns the lowest prime number that
+// is greater than or equal to n.
+//
+// The algorithm creates a list of small primes, plus an open-ended list of
+// potential primes.  All prime numbers are potential prime numbers.  However
+// some potential prime numbers are not prime.  In an ideal world, all potential
+// prime numbers would be prime.  Candidate prime numbers are chosen as the next
+// highest potential prime.  Then this number is tested for prime by dividing it
+// by all potential prime numbers less than the sqrt of the candidate.
+//
+// This implementation defines potential primes as those numbers not divisible
+// by 2, 3, 5, and 7.  Other (common) implementations define potential primes
+// as those not divisible by 2.  A few other implementations define potential
+// primes as those not divisible by 2 or 3.  By raising the number of small
+// primes which the potential prime is not divisible by, the set of potential
+// primes more closely approximates the set of prime numbers.  And thus there
+// are fewer potential primes to search, and fewer potential primes to divide
+// against.
+
+template <size_t _Sz = sizeof(size_t)>
+inline _LIBCPP_INLINE_VISIBILITY
+typename enable_if<_Sz == 4, void>::type
+__check_for_overflow(size_t N)
+{
+    if (N > 0xFFFFFFFB)
+        __throw_overflow_error("__next_prime overflow");
+}
+
+template <size_t _Sz = sizeof(size_t)>
+inline _LIBCPP_INLINE_VISIBILITY
+typename enable_if<_Sz == 8, void>::type
+__check_for_overflow(size_t N)
+{
+    if (N > 0xFFFFFFFFFFFFFFC5ull)
+        __throw_overflow_error("__next_prime overflow");
+}
+
+size_t
+__next_prime(size_t n)
+{
+    const size_t L = 210;
+    const size_t N = sizeof(small_primes) / sizeof(small_primes[0]);
+    // If n is small enough, search in small_primes
+    if (n <= small_primes[N-1])
+        return *std::lower_bound(small_primes, small_primes + N, n);
+    // Else n > largest small_primes
+    // Check for overflow
+    __check_for_overflow(n);
+    // Start searching list of potential primes: L * k0 + indices[in]
+    const size_t M = sizeof(indices) / sizeof(indices[0]);
+    // Select first potential prime >= n
+    //   Known a-priori n >= L
+    size_t k0 = n / L;
+    size_t in = static_cast<size_t>(std::lower_bound(indices, indices + M, n - k0 * L)
+                                    - indices);
+    n = L * k0 + indices[in];
+    while (true)
+    {
+        // Divide n by all primes or potential primes (i) until:
+        //    1.  The division is even, so try next potential prime.
+        //    2.  The i > sqrt(n), in which case n is prime.
+        // It is known a-priori that n is not divisible by 2, 3, 5 or 7,
+        //    so don't test those (j == 5 ->  divide by 11 first).  And the
+        //    potential primes start with 211, so don't test against the last
+        //    small prime.
+        for (size_t j = 5; j < N - 1; ++j)
+        {
+            const std::size_t p = small_primes[j];
+            const std::size_t q = n / p;
+            if (q < p)
+                return n;
+            if (n == q * p)
+                goto next;
+        }
+        // n wasn't divisible by small primes, try potential primes
+        {
+            size_t i = 211;
+            while (true)
+            {
+                std::size_t q = n / i;
+                if (q < i)
+                    return n;
+                if (n == q * i)
+                    break;
+
+                i += 10;
+                q = n / i;
+                if (q < i)
+                    return n;
+                if (n == q * i)
+                    break;
+
+                i += 2;
+                q = n / i;
+                if (q < i)
+                    return n;
+                if (n == q * i)
+                    break;
+
+                i += 4;
+                q = n / i;
+                if (q < i)
+                    return n;
+                if (n == q * i)
+                    break;
+
+                i += 2;
+                q = n / i;
+                if (q < i)
+                    return n;
+                if (n == q * i)
+                    break;
+
+                i += 4;
+                q = n / i;
+                if (q < i)
+                    return n;
+                if (n == q * i)
+                    break;
+
+                i += 6;
+                q = n / i;
+                if (q < i)
+                    return n;
+                if (n == q * i)
+                    break;
+
+                i += 2;
+                q = n / i;
+                if (q < i)
+                    return n;
+                if (n == q * i)
+                    break;
+
+                i += 6;
+                q = n / i;
+                if (q < i)
+                    return n;
+                if (n == q * i)
+                    break;
+
+                i += 4;
+                q = n / i;
+                if (q < i)
+                    return n;
+                if (n == q * i)
+                    break;
+
+                i += 2;
+                q = n / i;
+                if (q < i)
+                    return n;
+                if (n == q * i)
+                    break;
+
+                i += 4;
+                q = n / i;
+                if (q < i)
+                    return n;
+                if (n == q * i)
+                    break;
+
+                i += 6;
+                q = n / i;
+                if (q < i)
+                    return n;
+                if (n == q * i)
+                    break;
+
+                i += 6;
+                q = n / i;
+                if (q < i)
+                    return n;
+                if (n == q * i)
+                    break;
+
+                i += 2;
+                q = n / i;
+                if (q < i)
+                    return n;
+                if (n == q * i)
+                    break;
+
+                i += 6;
+                q = n / i;
+                if (q < i)
+                    return n;
+                if (n == q * i)
+                    break;
+
+                i += 4;
+                q = n / i;
+                if (q < i)
+                    return n;
+                if (n == q * i)
+                    break;
+
+                i += 2;
+                q = n / i;
+                if (q < i)
+                    return n;
+                if (n == q * i)
+                    break;
+
+                i += 6;
+                q = n / i;
+                if (q < i)
+                    return n;
+                if (n == q * i)
+                    break;
+
+                i += 4;
+                q = n / i;
+                if (q < i)
+                    return n;
+                if (n == q * i)
+                    break;
+
+                i += 6;
+                q = n / i;
+                if (q < i)
+                    return n;
+                if (n == q * i)
+                    break;
+
+                i += 8;
+                q = n / i;
+                if (q < i)
+                    return n;
+                if (n == q * i)
+                    break;
+
+                i += 4;
+                q = n / i;
+                if (q < i)
+                    return n;
+                if (n == q * i)
+                    break;
+
+                i += 2;
+                q = n / i;
+                if (q < i)
+                    return n;
+                if (n == q * i)
+                    break;
+
+                i += 4;
+                q = n / i;
+                if (q < i)
+                    return n;
+                if (n == q * i)
+                    break;
+
+                i += 2;
+                q = n / i;
+                if (q < i)
+                    return n;
+                if (n == q * i)
+                    break;
+
+                i += 4;
+                q = n / i;
+                if (q < i)
+                    return n;
+                if (n == q * i)
+                    break;
+
+                i += 8;
+                q = n / i;
+                if (q < i)
+                    return n;
+                if (n == q * i)
+                    break;
+
+                i += 6;
+                q = n / i;
+                if (q < i)
+                    return n;
+                if (n == q * i)
+                    break;
+
+                i += 4;
+                q = n / i;
+                if (q < i)
+                    return n;
+                if (n == q * i)
+                    break;
+
+                i += 6;
+                q = n / i;
+                if (q < i)
+                    return n;
+                if (n == q * i)
+                    break;
+
+                i += 2;
+                q = n / i;
+                if (q < i)
+                    return n;
+                if (n == q * i)
+                    break;
+
+                i += 4;
+                q = n / i;
+                if (q < i)
+                    return n;
+                if (n == q * i)
+                    break;
+
+                i += 6;
+                q = n / i;
+                if (q < i)
+                    return n;
+                if (n == q * i)
+                    break;
+
+                i += 2;
+                q = n / i;
+                if (q < i)
+                    return n;
+                if (n == q * i)
+                    break;
+
+                i += 6;
+                q = n / i;
+                if (q < i)
+                    return n;
+                if (n == q * i)
+                    break;
+
+                i += 6;
+                q = n / i;
+                if (q < i)
+                    return n;
+                if (n == q * i)
+                    break;
+
+                i += 4;
+                q = n / i;
+                if (q < i)
+                    return n;
+                if (n == q * i)
+                    break;
+
+                i += 2;
+                q = n / i;
+                if (q < i)
+                    return n;
+                if (n == q * i)
+                    break;
+
+                i += 4;
+                q = n / i;
+                if (q < i)
+                    return n;
+                if (n == q * i)
+                    break;
+
+                i += 6;
+                q = n / i;
+                if (q < i)
+                    return n;
+                if (n == q * i)
+                    break;
+
+                i += 2;
+                q = n / i;
+                if (q < i)
+                    return n;
+                if (n == q * i)
+                    break;
+
+                i += 6;
+                q = n / i;
+                if (q < i)
+                    return n;
+                if (n == q * i)
+                    break;
+
+                i += 4;
+                q = n / i;
+                if (q < i)
+                    return n;
+                if (n == q * i)
+                    break;
+
+                i += 2;
+                q = n / i;
+                if (q < i)
+                    return n;
+                if (n == q * i)
+                    break;
+
+                i += 4;
+                q = n / i;
+                if (q < i)
+                    return n;
+                if (n == q * i)
+                    break;
+
+                i += 2;
+                q = n / i;
+                if (q < i)
+                    return n;
+                if (n == q * i)
+                    break;
+
+                i += 10;
+                q = n / i;
+                if (q < i)
+                    return n;
+                if (n == q * i)
+                    break;
+
+                // This will loop i to the next "plane" of potential primes
+                i += 2;
+            }
+        }
+next:
+        // n is not prime.  Increment n to next potential prime.
+        if (++in == M)
+        {
+            ++k0;
+            in = 0;
+        }
+        n = L * k0 + indices[in];
+    }
+}
+
+_LIBCPP_END_NAMESPACE_STD

third_party/libcxx/src/include/apple_availability.h

@@ -0,0 +1,34 @@
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef _LIBCPP_SRC_INCLUDE_APPLE_AVAILABILITY_H
+#define _LIBCPP_SRC_INCLUDE_APPLE_AVAILABILITY_H
+
+#if defined(__APPLE__)
+
+#if defined(__ENVIRONMENT_MAC_OS_X_VERSION_MIN_REQUIRED__)
+#if __ENVIRONMENT_MAC_OS_X_VERSION_MIN_REQUIRED__ >= 101500
+#define _LIBCPP_USE_ULOCK
+#endif
+#elif defined(__ENVIRONMENT_IPHONE_OS_VERSION_MIN_REQUIRED__)
+#if __ENVIRONMENT_IPHONE_OS_VERSION_MIN_REQUIRED__ >= 130000
+#define _LIBCPP_USE_ULOCK
+#endif
+#elif defined(__ENVIRONMENT_TV_OS_VERSION_MIN_REQUIRED__)
+#if __ENVIRONMENT_TV_OS_VERSION_MIN_REQUIRED__ >= 130000
+#define _LIBCPP_USE_ULOCK
+#endif
+#elif defined(__ENVIRONMENT_WATCH_OS_VERSION_MIN_REQUIRED__)
+#if __ENVIRONMENT_WATCH_OS_VERSION_MIN_REQUIRED__ >= 60000
+#define _LIBCPP_USE_ULOCK
+#endif
+#endif // __ENVIRONMENT_.*_VERSION_MIN_REQUIRED__
+
+#endif // __APPLE__
+
+#endif // _LIBCPP_SRC_INCLUDE_APPLE_AVAILABILITY_H

third_party/libcxx/src/include/atomic_support.h

@@ -0,0 +1,176 @@
+//===----------------------------------------------------------------------===////
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===////
+
+#ifndef ATOMIC_SUPPORT_H
+#define ATOMIC_SUPPORT_H
+
+#include <__config>
+#include <memory> // for __libcpp_relaxed_load
+
+#if defined(__clang__) && __has_builtin(__atomic_load_n)             \
+                       && __has_builtin(__atomic_store_n)            \
+                       && __has_builtin(__atomic_add_fetch)          \
+                       && __has_builtin(__atomic_exchange_n)         \
+                       && __has_builtin(__atomic_compare_exchange_n) \
+                       && defined(__ATOMIC_RELAXED)                  \
+                       && defined(__ATOMIC_CONSUME)                  \
+                       && defined(__ATOMIC_ACQUIRE)                  \
+                       && defined(__ATOMIC_RELEASE)                  \
+                       && defined(__ATOMIC_ACQ_REL)                  \
+                       && defined(__ATOMIC_SEQ_CST)
+#   define _LIBCPP_HAS_ATOMIC_BUILTINS
+#elif defined(_LIBCPP_COMPILER_GCC)
+#   define _LIBCPP_HAS_ATOMIC_BUILTINS
+#endif
+
+#if !defined(_LIBCPP_HAS_ATOMIC_BUILTINS) && !defined(_LIBCPP_HAS_NO_THREADS)
+# if defined(_LIBCPP_WARNING)
+    _LIBCPP_WARNING("Building libc++ without __atomic builtins is unsupported")
+# else
+#   warning Building libc++ without __atomic builtins is unsupported
+# endif
+#endif
+
+_LIBCPP_BEGIN_NAMESPACE_STD
+
+namespace {
+
+#if defined(_LIBCPP_HAS_ATOMIC_BUILTINS) && !defined(_LIBCPP_HAS_NO_THREADS)
+
+enum __libcpp_atomic_order {
+    _AO_Relaxed = __ATOMIC_RELAXED,
+    _AO_Consume = __ATOMIC_CONSUME,
+    _AO_Acquire = __ATOMIC_ACQUIRE,
+    _AO_Release = __ATOMIC_RELEASE,
+    _AO_Acq_Rel = __ATOMIC_ACQ_REL,
+    _AO_Seq     = __ATOMIC_SEQ_CST
+};
+
+template <class _ValueType, class _FromType>
+inline _LIBCPP_INLINE_VISIBILITY
+void __libcpp_atomic_store(_ValueType* __dest, _FromType __val,
+                           int __order = _AO_Seq)
+{
+    __atomic_store_n(__dest, __val, __order);
+}
+
+template <class _ValueType, class _FromType>
+inline _LIBCPP_INLINE_VISIBILITY
+void __libcpp_relaxed_store(_ValueType* __dest, _FromType __val)
+{
+    __atomic_store_n(__dest, __val, _AO_Relaxed);
+}
+
+template <class _ValueType>
+inline _LIBCPP_INLINE_VISIBILITY
+_ValueType __libcpp_atomic_load(_ValueType const* __val,
+                                int __order = _AO_Seq)
+{
+    return __atomic_load_n(__val, __order);
+}
+
+template <class _ValueType, class _AddType>
+inline _LIBCPP_INLINE_VISIBILITY
+_ValueType __libcpp_atomic_add(_ValueType* __val, _AddType __a,
+                               int __order = _AO_Seq)
+{
+    return __atomic_add_fetch(__val, __a, __order);
+}
+
+template <class _ValueType>
+inline _LIBCPP_INLINE_VISIBILITY
+_ValueType __libcpp_atomic_exchange(_ValueType* __target,
+                                    _ValueType __value, int __order = _AO_Seq)
+{
+    return __atomic_exchange_n(__target, __value, __order);
+}
+
+template <class _ValueType>
+inline _LIBCPP_INLINE_VISIBILITY
+bool __libcpp_atomic_compare_exchange(_ValueType* __val,
+    _ValueType* __expected, _ValueType __after,
+    int __success_order = _AO_Seq,
+    int __fail_order = _AO_Seq)
+{
+    return __atomic_compare_exchange_n(__val, __expected, __after, true,
+                                       __success_order, __fail_order);
+}
+
+#else // _LIBCPP_HAS_NO_THREADS
+
+enum __libcpp_atomic_order {
+    _AO_Relaxed,
+    _AO_Consume,
+    _AO_Acquire,
+    _AO_Release,
+    _AO_Acq_Rel,
+    _AO_Seq
+};
+
+template <class _ValueType, class _FromType>
+inline _LIBCPP_INLINE_VISIBILITY
+void __libcpp_atomic_store(_ValueType* __dest, _FromType __val,
+                           int = 0)
+{
+    *__dest = __val;
+}
+
+template <class _ValueType, class _FromType>
+inline _LIBCPP_INLINE_VISIBILITY
+void __libcpp_relaxed_store(_ValueType* __dest, _FromType __val)
+{
+    *__dest = __val;
+}
+
+template <class _ValueType>
+inline _LIBCPP_INLINE_VISIBILITY
+_ValueType __libcpp_atomic_load(_ValueType const* __val,
+                                int = 0)
+{
+    return *__val;
+}
+
+template <class _ValueType, class _AddType>
+inline _LIBCPP_INLINE_VISIBILITY
+_ValueType __libcpp_atomic_add(_ValueType* __val, _AddType __a,
+                               int = 0)
+{
+    return *__val += __a;
+}
+
+template <class _ValueType>
+inline _LIBCPP_INLINE_VISIBILITY
+_ValueType __libcpp_atomic_exchange(_ValueType* __target,
+                                    _ValueType __value, int = _AO_Seq)
+{
+    _ValueType old = *__target;
+    *__target = __value;
+    return old;
+}
+
+template <class _ValueType>
+inline _LIBCPP_INLINE_VISIBILITY
+bool __libcpp_atomic_compare_exchange(_ValueType* __val,
+    _ValueType* __expected, _ValueType __after,
+    int = 0, int = 0)
+{
+    if (*__val == *__expected) {
+        *__val = __after;
+        return true;
+    }
+    *__expected = *__val;
+    return false;
+}
+
+#endif // _LIBCPP_HAS_NO_THREADS
+
+} // end namespace
+
+_LIBCPP_END_NAMESPACE_STD
+
+#endif // ATOMIC_SUPPORT_H

third_party/libcxx/src/include/config_elast.h

@@ -0,0 +1,51 @@
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef _LIBCPP_CONFIG_ELAST
+#define _LIBCPP_CONFIG_ELAST
+
+#include <__config>
+
+#if defined(_LIBCPP_MSVCRT_LIKE)
+#include <stdlib.h>
+#else
+#include <errno.h>
+#endif
+
+// Note: _LIBCPP_ELAST needs to be defined only on platforms
+// where strerror/strerror_r can't handle out-of-range errno values.
+#if defined(ELAST)
+#define _LIBCPP_ELAST ELAST
+#elif defined(_NEWLIB_VERSION)
+#define _LIBCPP_ELAST __ELASTERROR
+#elif defined(__NuttX__)
+// No _LIBCPP_ELAST needed on NuttX
+#elif defined(__Fuchsia__)
+// No _LIBCPP_ELAST needed on Fuchsia
+#elif defined(__wasi__)
+// No _LIBCPP_ELAST needed on WASI
+#elif defined(__EMSCRIPTEN__)
+// No _LIBCPP_ELAST needed on Emscripten
+#elif defined(__COSMOPOLITAN__)
+#define _LIBCPP_ELAST 65535
+#elif defined(__linux__) || defined(_LIBCPP_HAS_MUSL_LIBC)
+#define _LIBCPP_ELAST 4095
+#elif defined(__APPLE__)
+// No _LIBCPP_ELAST needed on Apple
+#elif defined(__MVS__)
+#define _LIBCPP_ELAST 1160
+#elif defined(_LIBCPP_MSVCRT_LIKE)
+#define _LIBCPP_ELAST (_sys_nerr - 1)
+#elif defined(_AIX)
+#define _LIBCPP_ELAST 127
+#else
+// Warn here so that the person doing the libcxx port has an easier time:
+#warning ELAST for this platform not yet implemented
+#endif
+
+#endif // _LIBCPP_CONFIG_ELAST

third_party/libcxx/src/include/refstring.h

@@ -0,0 +1,140 @@
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef _LIBCPP_REFSTRING_H
+#define _LIBCPP_REFSTRING_H
+
+#include <__config>
+#include <stdexcept>
+#include <cstddef>
+#include <cstring>
+#include "atomic_support.h"
+
+// MacOS and iOS used to ship with libstdc++, and still support old applications
+// linking against libstdc++. The libc++ and libstdc++ exceptions are supposed
+// to be ABI compatible, such that they can be thrown from one library and caught
+// in the other.
+//
+// For that reason, we must look for libstdc++ in the same process and if found,
+// check the string stored in the exception object to see if it is the GCC empty
+// string singleton before manipulating the reference count. This is done so that
+// if an exception is created with a zero-length string in libstdc++, libc++abi
+// won't try to delete the memory.
+#if defined(__ENVIRONMENT_MAC_OS_X_VERSION_MIN_REQUIRED__) || \
+    defined(__ENVIRONMENT_IPHONE_OS_VERSION_MIN_REQUIRED__)
+#   define _LIBCPP_CHECK_FOR_GCC_EMPTY_STRING_STORAGE
+#   include <dlfcn.h>
+#   include <mach-o/dyld.h>
+#endif
+
+_LIBCPP_BEGIN_NAMESPACE_STD
+
+namespace __refstring_imp { namespace {
+typedef int count_t;
+
+struct _Rep_base {
+    std::size_t len;
+    std::size_t cap;
+    count_t     count;
+};
+
+inline _Rep_base* rep_from_data(const char *data_) noexcept {
+    char *data = const_cast<char *>(data_);
+    return reinterpret_cast<_Rep_base *>(data - sizeof(_Rep_base));
+}
+
+inline char * data_from_rep(_Rep_base *rep) noexcept {
+    char *data = reinterpret_cast<char *>(rep);
+    return data + sizeof(*rep);
+}
+
+#if defined(_LIBCPP_CHECK_FOR_GCC_EMPTY_STRING_STORAGE)
+inline
+const char* compute_gcc_empty_string_storage() noexcept
+{
+    void* handle = dlopen("/usr/lib/libstdc++.6.dylib", RTLD_NOLOAD);
+    if (handle == nullptr)
+        return nullptr;
+    void* sym = dlsym(handle, "_ZNSs4_Rep20_S_empty_rep_storageE");
+    if (sym == nullptr)
+        return nullptr;
+    return data_from_rep(reinterpret_cast<_Rep_base *>(sym));
+}
+
+inline
+const char*
+get_gcc_empty_string_storage() noexcept
+{
+    static const char* p = compute_gcc_empty_string_storage();
+    return p;
+}
+#endif
+
+}} // namespace __refstring_imp
+
+using namespace __refstring_imp;
+
+inline
+__libcpp_refstring::__libcpp_refstring(const char* msg) {
+    std::size_t len = strlen(msg);
+    _Rep_base* rep = static_cast<_Rep_base *>(::operator new(sizeof(*rep) + len + 1));
+    rep->len = len;
+    rep->cap = len;
+    rep->count = 0;
+    char *data = data_from_rep(rep);
+    std::memcpy(data, msg, len + 1);
+    __imp_ = data;
+}
+
+inline
+__libcpp_refstring::__libcpp_refstring(const __libcpp_refstring &s) noexcept
+    : __imp_(s.__imp_)
+{
+    if (__uses_refcount())
+        __libcpp_atomic_add(&rep_from_data(__imp_)->count, 1);
+}
+
+inline
+__libcpp_refstring& __libcpp_refstring::operator=(__libcpp_refstring const& s) noexcept {
+    bool adjust_old_count = __uses_refcount();
+    struct _Rep_base *old_rep = rep_from_data(__imp_);
+    __imp_ = s.__imp_;
+    if (__uses_refcount())
+        __libcpp_atomic_add(&rep_from_data(__imp_)->count, 1);
+    if (adjust_old_count)
+    {
+        if (__libcpp_atomic_add(&old_rep->count, count_t(-1)) < 0)
+        {
+            ::operator delete(old_rep);
+        }
+    }
+    return *this;
+}
+
+inline
+__libcpp_refstring::~__libcpp_refstring() {
+    if (__uses_refcount()) {
+        _Rep_base* rep = rep_from_data(__imp_);
+        if (__libcpp_atomic_add(&rep->count, count_t(-1)) < 0) {
+            ::operator delete(rep);
+        }
+    }
+}
+
+inline
+bool __libcpp_refstring::__uses_refcount() const {
+#if defined(_LIBCPP_CHECK_FOR_GCC_EMPTY_STRING_STORAGE)
+    return __imp_ != get_gcc_empty_string_storage();
+#else
+    return true;
+#endif
+}
+
+_LIBCPP_END_NAMESPACE_STD
+
+#endif //_LIBCPP_REFSTRING_H

third_party/libcxx/src/include/ryu/common.h

@@ -0,0 +1,109 @@
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+// Copyright (c) Microsoft Corporation.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+
+// Copyright 2018 Ulf Adams
+// Copyright (c) Microsoft Corporation. All rights reserved.
+
+// Boost Software License - Version 1.0 - August 17th, 2003
+
+// Permission is hereby granted, free of charge, to any person or organization
+// obtaining a copy of the software and accompanying documentation covered by
+// this license (the "Software") to use, reproduce, display, distribute,
+// execute, and transmit the Software, and to prepare derivative works of the
+// Software, and to permit third-parties to whom the Software is furnished to
+// do so, all subject to the following:
+
+// The copyright notices in the Software and this entire statement, including
+// the above license grant, this restriction and the following disclaimer,
+// must be included in all copies of the Software, in whole or in part, and
+// all derivative works of the Software, unless such copies or derivative
+// works are solely in the form of machine-executable object code generated by
+// a source language processor.
+
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+// FITNESS FOR A PARTICULAR PURPOSE, TITLE AND NON-INFRINGEMENT. IN NO EVENT
+// SHALL THE COPYRIGHT HOLDERS OR ANYONE DISTRIBUTING THE SOFTWARE BE LIABLE
+// FOR ANY DAMAGES OR OTHER LIABILITY, WHETHER IN CONTRACT, TORT OR OTHERWISE,
+// ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
+// DEALINGS IN THE SOFTWARE.
+
+#ifndef _LIBCPP_SRC_INCLUDE_RYU_COMMON_H
+#define _LIBCPP_SRC_INCLUDE_RYU_COMMON_H
+
+// Avoid formatting to keep the changes with the original code minimal.
+// clang-format off
+
+#include <__assert>
+#include <__config>
+#include <cstring>
+
+_LIBCPP_BEGIN_NAMESPACE_STD
+
+[[nodiscard]] _LIBCPP_HIDE_FROM_ABI inline uint32_t __decimalLength9(const uint32_t __v) {
+  // Function precondition: __v is not a 10-digit number.
+  // (f2s: 9 digits are sufficient for round-tripping.)
+  // (d2fixed: We print 9-digit blocks.)
+  _LIBCPP_ASSERT(__v < 1000000000, "");
+  if (__v >= 100000000) { return 9; }
+  if (__v >= 10000000) { return 8; }
+  if (__v >= 1000000) { return 7; }
+  if (__v >= 100000) { return 6; }
+  if (__v >= 10000) { return 5; }
+  if (__v >= 1000) { return 4; }
+  if (__v >= 100) { return 3; }
+  if (__v >= 10) { return 2; }
+  return 1;
+}
+
+// Returns __e == 0 ? 1 : ceil(log_2(5^__e)).
+[[nodiscard]] _LIBCPP_HIDE_FROM_ABI  inline int32_t __pow5bits(const int32_t __e) {
+  // This approximation works up to the point that the multiplication overflows at __e = 3529.
+  // If the multiplication were done in 64 bits, it would fail at 5^4004 which is just greater
+  // than 2^9297.
+  _LIBCPP_ASSERT(__e >= 0, "");
+  _LIBCPP_ASSERT(__e <= 3528, "");
+  return static_cast<int32_t>(((static_cast<uint32_t>(__e) * 1217359) >> 19) + 1);
+}
+
+// Returns floor(log_10(2^__e)).
+[[nodiscard]] _LIBCPP_HIDE_FROM_ABI  inline uint32_t __log10Pow2(const int32_t __e) {
+  // The first value this approximation fails for is 2^1651 which is just greater than 10^297.
+  _LIBCPP_ASSERT(__e >= 0, "");
+  _LIBCPP_ASSERT(__e <= 1650, "");
+  return (static_cast<uint32_t>(__e) * 78913) >> 18;
+}
+
+// Returns floor(log_10(5^__e)).
+[[nodiscard]] _LIBCPP_HIDE_FROM_ABI inline uint32_t __log10Pow5(const int32_t __e) {
+  // The first value this approximation fails for is 5^2621 which is just greater than 10^1832.
+  _LIBCPP_ASSERT(__e >= 0, "");
+  _LIBCPP_ASSERT(__e <= 2620, "");
+  return (static_cast<uint32_t>(__e) * 732923) >> 20;
+}
+
+[[nodiscard]] _LIBCPP_HIDE_FROM_ABI inline uint32_t __float_to_bits(const float __f) {
+  uint32_t __bits = 0;
+  std::memcpy(&__bits, &__f, sizeof(float));
+  return __bits;
+}
+
+[[nodiscard]] _LIBCPP_HIDE_FROM_ABI inline uint64_t __double_to_bits(const double __d) {
+  uint64_t __bits = 0;
+  std::memcpy(&__bits, &__d, sizeof(double));
+  return __bits;
+}
+
+_LIBCPP_END_NAMESPACE_STD
+
+// clang-format on
+
+#endif // _LIBCPP_SRC_INCLUDE_RYU_COMMON_H

third_party/libcxx/src/include/ryu/d2fixed.h

@@ -0,0 +1,60 @@
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+// Copyright (c) Microsoft Corporation.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+
+// Copyright 2018 Ulf Adams
+// Copyright (c) Microsoft Corporation. All rights reserved.
+
+// Boost Software License - Version 1.0 - August 17th, 2003
+
+// Permission is hereby granted, free of charge, to any person or organization
+// obtaining a copy of the software and accompanying documentation covered by
+// this license (the "Software") to use, reproduce, display, distribute,
+// execute, and transmit the Software, and to prepare derivative works of the
+// Software, and to permit third-parties to whom the Software is furnished to
+// do so, all subject to the following:
+
+// The copyright notices in the Software and this entire statement, including
+// the above license grant, this restriction and the following disclaimer,
+// must be included in all copies of the Software, in whole or in part, and
+// all derivative works of the Software, unless such copies or derivative
+// works are solely in the form of machine-executable object code generated by
+// a source language processor.
+
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+// FITNESS FOR A PARTICULAR PURPOSE, TITLE AND NON-INFRINGEMENT. IN NO EVENT
+// SHALL THE COPYRIGHT HOLDERS OR ANYONE DISTRIBUTING THE SOFTWARE BE LIABLE
+// FOR ANY DAMAGES OR OTHER LIABILITY, WHETHER IN CONTRACT, TORT OR OTHERWISE,
+// ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
+// DEALINGS IN THE SOFTWARE.
+
+#ifndef _LIBCPP_SRC_INCLUDE_RYU_D2FIXED_H
+#define _LIBCPP_SRC_INCLUDE_RYU_D2FIXED_H
+
+// Avoid formatting to keep the changes with the original code minimal.
+// clang-format off
+
+#include <__config>
+#include <cstdint>
+
+_LIBCPP_BEGIN_NAMESPACE_STD
+
+void __append_n_digits(const uint32_t __olength, uint32_t __digits, char* const __result);
+void __append_nine_digits(uint32_t __digits, char* const __result);
+
+[[nodiscard]] to_chars_result __d2fixed_buffered_n(char* _First, char* const _Last, const double __d, const uint32_t __precision);
+[[nodiscard]] to_chars_result __d2exp_buffered_n(char* _First, char* const _Last, const double __d, uint32_t __precision);
+
+_LIBCPP_END_NAMESPACE_STD
+
+// clang-format on
+
+#endif // _LIBCPP_SRC_INCLUDE_RYU_D2FIXED_H

third_party/libcxx/src/include/ryu/d2s.h

@@ -0,0 +1,62 @@
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+// Copyright (c) Microsoft Corporation.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+
+// Copyright 2018 Ulf Adams
+// Copyright (c) Microsoft Corporation. All rights reserved.
+
+// Boost Software License - Version 1.0 - August 17th, 2003
+
+// Permission is hereby granted, free of charge, to any person or organization
+// obtaining a copy of the software and accompanying documentation covered by
+// this license (the "Software") to use, reproduce, display, distribute,
+// execute, and transmit the Software, and to prepare derivative works of the
+// Software, and to permit third-parties to whom the Software is furnished to
+// do so, all subject to the following:
+
+// The copyright notices in the Software and this entire statement, including
+// the above license grant, this restriction and the following disclaimer,
+// must be included in all copies of the Software, in whole or in part, and
+// all derivative works of the Software, unless such copies or derivative
+// works are solely in the form of machine-executable object code generated by
+// a source language processor.
+
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+// FITNESS FOR A PARTICULAR PURPOSE, TITLE AND NON-INFRINGEMENT. IN NO EVENT
+// SHALL THE COPYRIGHT HOLDERS OR ANYONE DISTRIBUTING THE SOFTWARE BE LIABLE
+// FOR ANY DAMAGES OR OTHER LIABILITY, WHETHER IN CONTRACT, TORT OR OTHERWISE,
+// ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
+// DEALINGS IN THE SOFTWARE.
+
+#ifndef _LIBCPP_SRC_INCLUDE_RYU_DS2_H
+#define _LIBCPP_SRC_INCLUDE_RYU_DS2_H
+
+// Avoid formatting to keep the changes with the original code minimal.
+// clang-format off
+
+#include <__config>
+
+_LIBCPP_BEGIN_NAMESPACE_STD
+
+inline constexpr int __DOUBLE_MANTISSA_BITS = 52;
+inline constexpr int __DOUBLE_EXPONENT_BITS = 11;
+inline constexpr int __DOUBLE_BIAS = 1023;
+
+inline constexpr int __DOUBLE_POW5_INV_BITCOUNT = 122;
+inline constexpr int __DOUBLE_POW5_BITCOUNT = 121;
+
+[[nodiscard]] to_chars_result __d2s_buffered_n(char* const _First, char* const _Last, const double __f, const chars_format _Fmt);
+
+_LIBCPP_END_NAMESPACE_STD
+
+// clang-format on
+
+#endif // _LIBCPP_SRC_INCLUDE_RYU_DS2_H

third_party/libcxx/src/include/ryu/d2s_full_table.h

@@ -0,0 +1,368 @@
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+// Copyright (c) Microsoft Corporation.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+
+// Copyright 2018 Ulf Adams
+// Copyright (c) Microsoft Corporation. All rights reserved.
+
+// Boost Software License - Version 1.0 - August 17th, 2003
+
+// Permission is hereby granted, free of charge, to any person or organization
+// obtaining a copy of the software and accompanying documentation covered by
+// this license (the "Software") to use, reproduce, display, distribute,
+// execute, and transmit the Software, and to prepare derivative works of the
+// Software, and to permit third-parties to whom the Software is furnished to
+// do so, all subject to the following:
+
+// The copyright notices in the Software and this entire statement, including
+// the above license grant, this restriction and the following disclaimer,
+// must be included in all copies of the Software, in whole or in part, and
+// all derivative works of the Software, unless such copies or derivative
+// works are solely in the form of machine-executable object code generated by
+// a source language processor.
+
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+// FITNESS FOR A PARTICULAR PURPOSE, TITLE AND NON-INFRINGEMENT. IN NO EVENT
+// SHALL THE COPYRIGHT HOLDERS OR ANYONE DISTRIBUTING THE SOFTWARE BE LIABLE
+// FOR ANY DAMAGES OR OTHER LIABILITY, WHETHER IN CONTRACT, TORT OR OTHERWISE,
+// ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
+// DEALINGS IN THE SOFTWARE.
+
+#ifndef _LIBCPP_SRC_INCLUDE_RYU_D2S_FULL_TABLE_H
+#define _LIBCPP_SRC_INCLUDE_RYU_D2S_FULL_TABLE_H
+
+// Avoid formatting to keep the changes with the original code minimal.
+// clang-format off
+
+#include <__config>
+
+_LIBCPP_BEGIN_NAMESPACE_STD
+
+inline constexpr uint64_t __DOUBLE_POW5_INV_SPLIT[292][2] = {
+  {                    1u, 288230376151711744u }, {  3689348814741910324u, 230584300921369395u },
+  {  2951479051793528259u, 184467440737095516u }, { 17118578500402463900u, 147573952589676412u },
+  { 12632330341676300947u, 236118324143482260u }, { 10105864273341040758u, 188894659314785808u },
+  { 15463389048156653253u, 151115727451828646u }, { 17362724847566824558u, 241785163922925834u },
+  { 17579528692795369969u, 193428131138340667u }, {  6684925324752475329u, 154742504910672534u },
+  { 18074578149087781173u, 247588007857076054u }, { 18149011334012135262u, 198070406285660843u },
+  {  3451162622983977240u, 158456325028528675u }, {  5521860196774363583u, 253530120045645880u },
+  {  4417488157419490867u, 202824096036516704u }, {  7223339340677503017u, 162259276829213363u },
+  {  7867994130342094503u, 259614842926741381u }, {  2605046489531765280u, 207691874341393105u },
+  {  2084037191625412224u, 166153499473114484u }, { 10713157136084480204u, 265845599156983174u },
+  { 12259874523609494487u, 212676479325586539u }, { 13497248433629505913u, 170141183460469231u },
+  { 14216899864323388813u, 272225893536750770u }, { 11373519891458711051u, 217780714829400616u },
+  {  5409467098425058518u, 174224571863520493u }, {  4965798542738183305u, 278759314981632789u },
+  {  7661987648932456967u, 223007451985306231u }, {  2440241304404055250u, 178405961588244985u },
+  {  3904386087046488400u, 285449538541191976u }, { 17880904128604832013u, 228359630832953580u },
+  { 14304723302883865611u, 182687704666362864u }, { 15133127457049002812u, 146150163733090291u },
+  { 16834306301794583852u, 233840261972944466u }, {  9778096226693756759u, 187072209578355573u },
+  { 15201174610838826053u, 149657767662684458u }, {  2185786488890659746u, 239452428260295134u },
+  {  5437978005854438120u, 191561942608236107u }, { 15418428848909281466u, 153249554086588885u },
+  {  6222742084545298729u, 245199286538542217u }, { 16046240111861969953u, 196159429230833773u },
+  {  1768945645263844993u, 156927543384667019u }, { 10209010661905972635u, 251084069415467230u },
+  {  8167208529524778108u, 200867255532373784u }, { 10223115638361732810u, 160693804425899027u },
+  {  1599589762411131202u, 257110087081438444u }, {  4969020624670815285u, 205688069665150755u },
+  {  3975216499736652228u, 164550455732120604u }, { 13739044029062464211u, 263280729171392966u },
+  {  7301886408508061046u, 210624583337114373u }, { 13220206756290269483u, 168499666669691498u },
+  { 17462981995322520850u, 269599466671506397u }, {  6591687966774196033u, 215679573337205118u },
+  { 12652048002903177473u, 172543658669764094u }, {  9175230360419352987u, 276069853871622551u },
+  {  3650835473593572067u, 220855883097298041u }, { 17678063637842498946u, 176684706477838432u },
+  { 13527506561580357021u, 282695530364541492u }, {  3443307619780464970u, 226156424291633194u },
+  {  6443994910566282300u, 180925139433306555u }, {  5155195928453025840u, 144740111546645244u },
+  { 15627011115008661990u, 231584178474632390u }, { 12501608892006929592u, 185267342779705912u },
+  {  2622589484121723027u, 148213874223764730u }, {  4196143174594756843u, 237142198758023568u },
+  { 10735612169159626121u, 189713759006418854u }, { 12277838550069611220u, 151771007205135083u },
+  { 15955192865369467629u, 242833611528216133u }, {  1696107848069843133u, 194266889222572907u },
+  { 12424932722681605476u, 155413511378058325u }, {  1433148282581017146u, 248661618204893321u },
+  { 15903913885032455010u, 198929294563914656u }, {  9033782293284053685u, 159143435651131725u },
+  { 14454051669254485895u, 254629497041810760u }, { 11563241335403588716u, 203703597633448608u },
+  { 16629290697806691620u, 162962878106758886u }, {   781423413297334329u, 260740604970814219u },
+  {  4314487545379777786u, 208592483976651375u }, {  3451590036303822229u, 166873987181321100u },
+  {  5522544058086115566u, 266998379490113760u }, {  4418035246468892453u, 213598703592091008u },
+  { 10913125826658934609u, 170878962873672806u }, { 10082303693170474728u, 273406340597876490u },
+  {  8065842954536379782u, 218725072478301192u }, { 17520720807854834795u, 174980057982640953u },
+  {  5897060404116273733u, 279968092772225526u }, {  1028299508551108663u, 223974474217780421u },
+  { 15580034865808528224u, 179179579374224336u }, { 17549358155809824511u, 286687326998758938u },
+  {  2971440080422128639u, 229349861599007151u }, { 17134547323305344204u, 183479889279205720u },
+  { 13707637858644275364u, 146783911423364576u }, { 14553522944347019935u, 234854258277383322u },
+  {  4264120725993795302u, 187883406621906658u }, { 10789994210278856888u, 150306725297525326u },
+  {  9885293106962350374u, 240490760476040522u }, {   529536856086059653u, 192392608380832418u },
+  {  7802327114352668369u, 153914086704665934u }, {  1415676938738538420u, 246262538727465495u },
+  {  1132541550990830736u, 197010030981972396u }, { 15663428499760305882u, 157608024785577916u },
+  { 17682787970132668764u, 252172839656924666u }, { 10456881561364224688u, 201738271725539733u },
+  { 15744202878575200397u, 161390617380431786u }, { 17812026976236499989u, 258224987808690858u },
+  {  3181575136763469022u, 206579990246952687u }, { 13613306553636506187u, 165263992197562149u },
+  { 10713244041592678929u, 264422387516099439u }, { 12259944048016053467u, 211537910012879551u },
+  {  6118606423670932450u, 169230328010303641u }, {  2411072648389671274u, 270768524816485826u },
+  { 16686253377679378312u, 216614819853188660u }, { 13349002702143502650u, 173291855882550928u },
+  { 17669055508687693916u, 277266969412081485u }, { 14135244406950155133u, 221813575529665188u },
+  {   240149081334393137u, 177450860423732151u }, { 11452284974360759988u, 283921376677971441u },
+  {  5472479164746697667u, 227137101342377153u }, { 11756680961281178780u, 181709681073901722u },
+  {  2026647139541122378u, 145367744859121378u }, { 18000030682233437097u, 232588391774594204u },
+  { 18089373360528660001u, 186070713419675363u }, {  3403452244197197031u, 148856570735740291u },
+  { 16513570034941246220u, 238170513177184465u }, { 13210856027952996976u, 190536410541747572u },
+  {  3189987192878576934u, 152429128433398058u }, {  1414630693863812771u, 243886605493436893u },
+  {  8510402184574870864u, 195109284394749514u }, { 10497670562401807014u, 156087427515799611u },
+  {  9417575270359070576u, 249739884025279378u }, { 14912757845771077107u, 199791907220223502u },
+  {  4551508647133041040u, 159833525776178802u }, { 10971762650154775986u, 255733641241886083u },
+  { 16156107749607641435u, 204586912993508866u }, {  9235537384944202825u, 163669530394807093u },
+  { 11087511001168814197u, 261871248631691349u }, { 12559357615676961681u, 209496998905353079u },
+  { 13736834907283479668u, 167597599124282463u }, { 18289587036911657145u, 268156158598851941u },
+  { 10942320814787415393u, 214524926879081553u }, { 16132554281313752961u, 171619941503265242u },
+  { 11054691591134363444u, 274591906405224388u }, { 16222450902391311402u, 219673525124179510u },
+  { 12977960721913049122u, 175738820099343608u }, { 17075388340318968271u, 281182112158949773u },
+  {  2592264228029443648u, 224945689727159819u }, {  5763160197165465241u, 179956551781727855u },
+  {  9221056315464744386u, 287930482850764568u }, { 14755542681855616155u, 230344386280611654u },
+  { 15493782960226403247u, 184275509024489323u }, {  1326979923955391628u, 147420407219591459u },
+  {  9501865507812447252u, 235872651551346334u }, { 11290841220991868125u, 188698121241077067u },
+  {  1653975347309673853u, 150958496992861654u }, { 10025058185179298811u, 241533595188578646u },
+  {  4330697733401528726u, 193226876150862917u }, { 14532604630946953951u, 154581500920690333u },
+  {  1116074521063664381u, 247330401473104534u }, {  4582208431592841828u, 197864321178483627u },
+  { 14733813189500004432u, 158291456942786901u }, { 16195403473716186445u, 253266331108459042u },
+  {  5577625149489128510u, 202613064886767234u }, {  8151448934333213131u, 162090451909413787u },
+  { 16731667109675051333u, 259344723055062059u }, { 17074682502481951390u, 207475778444049647u },
+  {  6281048372501740465u, 165980622755239718u }, {  6360328581260874421u, 265568996408383549u },
+  {  8777611679750609860u, 212455197126706839u }, { 10711438158542398211u, 169964157701365471u },
+  {  9759603424184016492u, 271942652322184754u }, { 11497031554089123517u, 217554121857747803u },
+  { 16576322872755119460u, 174043297486198242u }, { 11764721337440549842u, 278469275977917188u },
+  { 16790474699436260520u, 222775420782333750u }, { 13432379759549008416u, 178220336625867000u },
+  {  3045063541568861850u, 285152538601387201u }, { 17193446092222730773u, 228122030881109760u },
+  { 13754756873778184618u, 182497624704887808u }, { 18382503128506368341u, 145998099763910246u },
+  {  3586563302416817083u, 233596959622256395u }, {  2869250641933453667u, 186877567697805116u },
+  { 17052795772514404226u, 149502054158244092u }, { 12527077977055405469u, 239203286653190548u },
+  { 17400360011128145022u, 191362629322552438u }, {  2852241564676785048u, 153090103458041951u },
+  { 15631632947708587046u, 244944165532867121u }, {  8815957543424959314u, 195955332426293697u },
+  { 18120812478965698421u, 156764265941034957u }, { 14235904707377476180u, 250822825505655932u },
+  {  4010026136418160298u, 200658260404524746u }, { 17965416168102169531u, 160526608323619796u },
+  {  2919224165770098987u, 256842573317791675u }, {  2335379332616079190u, 205474058654233340u },
+  {  1868303466092863352u, 164379246923386672u }, {  6678634360490491686u, 263006795077418675u },
+  {  5342907488392393349u, 210405436061934940u }, {  4274325990713914679u, 168324348849547952u },
+  { 10528270399884173809u, 269318958159276723u }, { 15801313949391159694u, 215455166527421378u },
+  {  1573004715287196786u, 172364133221937103u }, { 17274202803427156150u, 275782613155099364u },
+  { 17508711057483635243u, 220626090524079491u }, { 10317620031244997871u, 176500872419263593u },
+  { 12818843235250086271u, 282401395870821749u }, { 13944423402941979340u, 225921116696657399u },
+  { 14844887537095493795u, 180736893357325919u }, { 15565258844418305359u, 144589514685860735u },
+  {  6457670077359736959u, 231343223497377177u }, { 16234182506113520537u, 185074578797901741u },
+  {  9297997190148906106u, 148059663038321393u }, { 11187446689496339446u, 236895460861314229u },
+  { 12639306166338981880u, 189516368689051383u }, { 17490142562555006151u, 151613094951241106u },
+  {  2158786396894637579u, 242580951921985771u }, { 16484424376483351356u, 194064761537588616u },
+  {  9498190686444770762u, 155251809230070893u }, { 11507756283569722895u, 248402894768113429u },
+  { 12895553841597688639u, 198722315814490743u }, { 17695140702761971558u, 158977852651592594u },
+  { 17244178680193423523u, 254364564242548151u }, { 10105994129412828495u, 203491651394038521u },
+  {  4395446488788352473u, 162793321115230817u }, { 10722063196803274280u, 260469313784369307u },
+  {  1198952927958798777u, 208375451027495446u }, { 15716557601334680315u, 166700360821996356u },
+  { 17767794532651667857u, 266720577315194170u }, { 14214235626121334286u, 213376461852155336u },
+  {  7682039686155157106u, 170701169481724269u }, {  1223217053622520399u, 273121871170758831u },
+  { 15735968901865657612u, 218497496936607064u }, { 16278123936234436413u, 174797997549285651u },
+  {   219556594781725998u, 279676796078857043u }, {  7554342905309201445u, 223741436863085634u },
+  {  9732823138989271479u, 178993149490468507u }, {   815121763415193074u, 286389039184749612u },
+  { 11720143854957885429u, 229111231347799689u }, { 13065463898708218666u, 183288985078239751u },
+  {  6763022304224664610u, 146631188062591801u }, {  3442138057275642729u, 234609900900146882u },
+  { 13821756890046245153u, 187687920720117505u }, { 11057405512036996122u, 150150336576094004u },
+  {  6623802375033462826u, 240240538521750407u }, { 16367088344252501231u, 192192430817400325u },
+  { 13093670675402000985u, 153753944653920260u }, {  2503129006933649959u, 246006311446272417u },
+  { 13070549649772650937u, 196805049157017933u }, { 17835137349301941396u, 157444039325614346u },
+  {  2710778055689733971u, 251910462920982955u }, {  2168622444551787177u, 201528370336786364u },
+  {  5424246770383340065u, 161222696269429091u }, {  1300097203129523457u, 257956314031086546u },
+  { 15797473021471260058u, 206365051224869236u }, {  8948629602435097724u, 165092040979895389u },
+  {  3249760919670425388u, 264147265567832623u }, {  9978506365220160957u, 211317812454266098u },
+  { 15361502721659949412u, 169054249963412878u }, {  2442311466204457120u, 270486799941460606u },
+  { 16711244431931206989u, 216389439953168484u }, { 17058344360286875914u, 173111551962534787u },
+  { 12535955717491360170u, 276978483140055660u }, { 10028764573993088136u, 221582786512044528u },
+  { 15401709288678291155u, 177266229209635622u }, {  9885339602917624555u, 283625966735416996u },
+  {  4218922867592189321u, 226900773388333597u }, { 14443184738299482427u, 181520618710666877u },
+  {  4175850161155765295u, 145216494968533502u }, { 10370709072591134795u, 232346391949653603u },
+  { 15675264887556728482u, 185877113559722882u }, {  5161514280561562140u, 148701690847778306u },
+  {   879725219414678777u, 237922705356445290u }, {   703780175531743021u, 190338164285156232u },
+  { 11631070584651125387u, 152270531428124985u }, {   162968861732249003u, 243632850284999977u },
+  { 11198421533611530172u, 194906280227999981u }, {  5269388412147313814u, 155925024182399985u },
+  {  8431021459435702103u, 249480038691839976u }, {  3055468352806651359u, 199584030953471981u },
+  { 17201769941212962380u, 159667224762777584u }, { 16454785461715008838u, 255467559620444135u },
+  { 13163828369372007071u, 204374047696355308u }, { 17909760324981426303u, 163499238157084246u },
+  {  2830174816776909822u, 261598781051334795u }, {  2264139853421527858u, 209279024841067836u },
+  { 16568707141704863579u, 167423219872854268u }, {  4373838538276319787u, 267877151796566830u },
+  {  3499070830621055830u, 214301721437253464u }, {  6488605479238754987u, 171441377149802771u },
+  {  3003071137298187333u, 274306203439684434u }, {  6091805724580460189u, 219444962751747547u },
+  { 15941491023890099121u, 175555970201398037u }, { 10748990379256517301u, 280889552322236860u },
+  {  8599192303405213841u, 224711641857789488u }, { 14258051472207991719u, 179769313486231590u }
+};
+
+inline constexpr uint64_t __DOUBLE_POW5_SPLIT[326][2] = {
+  {                    0u,  72057594037927936u }, {                    0u,  90071992547409920u },
+  {                    0u, 112589990684262400u }, {                    0u, 140737488355328000u },
+  {                    0u,  87960930222080000u }, {                    0u, 109951162777600000u },
+  {                    0u, 137438953472000000u }, {                    0u,  85899345920000000u },
+  {                    0u, 107374182400000000u }, {                    0u, 134217728000000000u },
+  {                    0u,  83886080000000000u }, {                    0u, 104857600000000000u },
+  {                    0u, 131072000000000000u }, {                    0u,  81920000000000000u },
+  {                    0u, 102400000000000000u }, {                    0u, 128000000000000000u },
+  {                    0u,  80000000000000000u }, {                    0u, 100000000000000000u },
+  {                    0u, 125000000000000000u }, {                    0u,  78125000000000000u },
+  {                    0u,  97656250000000000u }, {                    0u, 122070312500000000u },
+  {                    0u,  76293945312500000u }, {                    0u,  95367431640625000u },
+  {                    0u, 119209289550781250u }, {  4611686018427387904u,  74505805969238281u },
+  { 10376293541461622784u,  93132257461547851u }, {  8358680908399640576u, 116415321826934814u },
+  {   612489549322387456u,  72759576141834259u }, { 14600669991935148032u,  90949470177292823u },
+  { 13639151471491547136u, 113686837721616029u }, {  3213881284082270208u, 142108547152020037u },
+  {  4314518811765112832u,  88817841970012523u }, {   781462496279003136u, 111022302462515654u },
+  { 10200200157203529728u, 138777878078144567u }, { 13292654125893287936u,  86736173798840354u },
+  {  7392445620511834112u, 108420217248550443u }, {  4628871007212404736u, 135525271560688054u },
+  { 16728102434789916672u,  84703294725430033u }, {  7075069988205232128u, 105879118406787542u },
+  { 18067209522111315968u, 132348898008484427u }, {  8986162942105878528u,  82718061255302767u },
+  {  6621017659204960256u, 103397576569128459u }, {  3664586055578812416u, 129246970711410574u },
+  { 16125424340018921472u,  80779356694631608u }, {  1710036351314100224u, 100974195868289511u },
+  { 15972603494424788992u, 126217744835361888u }, {  9982877184015493120u,  78886090522101180u },
+  { 12478596480019366400u,  98607613152626475u }, { 10986559581596820096u, 123259516440783094u },
+  {  2254913720070624656u,  77037197775489434u }, { 12042014186943056628u,  96296497219361792u },
+  { 15052517733678820785u, 120370621524202240u }, {  9407823583549262990u,  75231638452626400u },
+  { 11759779479436578738u,  94039548065783000u }, { 14699724349295723422u, 117549435082228750u },
+  {  4575641699882439235u,  73468396926392969u }, { 10331238143280436948u,  91835496157991211u },
+  {  8302361660673158281u, 114794370197489014u }, {  1154580038986672043u, 143492962746861268u },
+  {  9944984561221445835u,  89683101716788292u }, { 12431230701526807293u, 112103877145985365u },
+  {  1703980321626345405u, 140129846432481707u }, { 17205888765512323542u,  87581154020301066u },
+  { 12283988920035628619u, 109476442525376333u }, {  1519928094762372062u, 136845553156720417u },
+  { 12479170105294952299u,  85528470722950260u }, { 15598962631618690374u, 106910588403687825u },
+  {  5663645234241199255u, 133638235504609782u }, { 17374836326682913246u,  83523897190381113u },
+  {  7883487353071477846u, 104404871487976392u }, {  9854359191339347308u, 130506089359970490u },
+  { 10770660513014479971u,  81566305849981556u }, { 13463325641268099964u, 101957882312476945u },
+  {  2994098996302961243u, 127447352890596182u }, { 15706369927971514489u,  79654595556622613u },
+  {  5797904354682229399u,  99568244445778267u }, {  2635694424925398845u, 124460305557222834u },
+  {  6258995034005762182u,  77787690973264271u }, {  3212057774079814824u,  97234613716580339u },
+  { 17850130272881932242u, 121543267145725423u }, { 18073860448192289507u,  75964541966078389u },
+  {  8757267504958198172u,  94955677457597987u }, {  6334898362770359811u, 118694596821997484u },
+  { 13182683513586250689u,  74184123013748427u }, { 11866668373555425458u,  92730153767185534u },
+  {  5609963430089506015u, 115912692208981918u }, { 17341285199088104971u,  72445432630613698u },
+  { 12453234462005355406u,  90556790788267123u }, { 10954857059079306353u, 113195988485333904u },
+  { 13693571323849132942u, 141494985606667380u }, { 17781854114260483896u,  88434366004167112u },
+  {  3780573569116053255u, 110542957505208891u }, {   114030942967678664u, 138178696881511114u },
+  {  4682955357782187069u,  86361685550944446u }, { 15077066234082509644u, 107952106938680557u },
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+  {  1794409976670715490u, 118305218616677471u }, {  8039035263060279037u,  73940761635423419u },
+  {  5437108060397960892u,  92425952044279274u }, { 16019757112352226923u, 115532440055349092u },
+  {   788976158365366019u,  72207775034593183u }, { 14821278253238871236u,  90259718793241478u },
+  {  9303225779693813237u, 112824648491551848u }, { 11629032224617266546u, 141030810614439810u },
+  { 11879831158813179495u,  88144256634024881u }, {  1014730893234310657u, 110180320792531102u },
+  { 10491785653397664129u, 137725400990663877u }, {  8863209042587234033u,  86078375619164923u },
+  {  6467325284806654637u, 107597969523956154u }, { 17307528642863094104u, 134497461904945192u },
+  { 10817205401789433815u,  84060913690590745u }, { 18133192770664180173u, 105076142113238431u },
+  { 18054804944902837312u, 131345177641548039u }, { 18201782118205355176u,  82090736025967524u },
+  {  4305483574047142354u, 102613420032459406u }, { 14605226504413703751u, 128266775040574257u },
+  {  2210737537617482988u,  80166734400358911u }, { 16598479977304017447u, 100208418000448638u },
+  { 11524727934775246001u, 125260522500560798u }, {  2591268940807140847u,  78287826562850499u },
+  { 17074144231291089770u,  97859783203563123u }, { 16730994270686474309u, 122324729004453904u },
+  { 10456871419179046443u,  76452955627783690u }, {  3847717237119032246u,  95566194534729613u },
+  {  9421332564826178211u, 119457743168412016u }, {  5888332853016361382u,  74661089480257510u },
+  { 16583788103125227536u,  93326361850321887u }, { 16118049110479146516u, 116657952312902359u },
+  { 16991309721690548428u,  72911220195563974u }, { 12015765115258409727u,  91139025244454968u },
+  { 15019706394073012159u, 113923781555568710u }, {  9551260955736489391u, 142404726944460888u },
+  {  5969538097335305869u,  89002954340288055u }, {  2850236603241744433u, 111253692925360069u }
+};
+
+_LIBCPP_END_NAMESPACE_STD
+
+// clang-format on
+
+#endif // _LIBCPP_SRC_INCLUDE_RYU_D2S_FULL_TABLE_H

third_party/libcxx/src/include/ryu/d2s_intrinsics.h

@@ -0,0 +1,260 @@
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+// Copyright (c) Microsoft Corporation.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+
+// Copyright 2018 Ulf Adams
+// Copyright (c) Microsoft Corporation. All rights reserved.
+
+// Boost Software License - Version 1.0 - August 17th, 2003
+
+// Permission is hereby granted, free of charge, to any person or organization
+// obtaining a copy of the software and accompanying documentation covered by
+// this license (the "Software") to use, reproduce, display, distribute,
+// execute, and transmit the Software, and to prepare derivative works of the
+// Software, and to permit third-parties to whom the Software is furnished to
+// do so, all subject to the following:
+
+// The copyright notices in the Software and this entire statement, including
+// the above license grant, this restriction and the following disclaimer,
+// must be included in all copies of the Software, in whole or in part, and
+// all derivative works of the Software, unless such copies or derivative
+// works are solely in the form of machine-executable object code generated by
+// a source language processor.
+
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+// FITNESS FOR A PARTICULAR PURPOSE, TITLE AND NON-INFRINGEMENT. IN NO EVENT
+// SHALL THE COPYRIGHT HOLDERS OR ANYONE DISTRIBUTING THE SOFTWARE BE LIABLE
+// FOR ANY DAMAGES OR OTHER LIABILITY, WHETHER IN CONTRACT, TORT OR OTHERWISE,
+// ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
+// DEALINGS IN THE SOFTWARE.
+
+#ifndef _LIBCPP_SRC_INCLUDE_RYU_DS2_INTRINSICS_H
+#define _LIBCPP_SRC_INCLUDE_RYU_DS2_INTRINSICS_H
+
+// Avoid formatting to keep the changes with the original code minimal.
+// clang-format off
+
+#include <__assert>
+#include <__config>
+
+#include "third_party/libcxx/src/include/ryu/ryu.h"
+
+_LIBCPP_BEGIN_NAMESPACE_STD
+
+#if defined(_M_X64) && defined(_MSC_VER)
+#define _LIBCPP_INTRINSIC128 1
+[[nodiscard]] _LIBCPP_HIDE_FROM_ABI inline uint64_t __ryu_umul128(const uint64_t __a, const uint64_t __b, uint64_t* const __productHi) {
+  return _umul128(__a, __b, __productHi);
+}
+
+[[nodiscard]] _LIBCPP_HIDE_FROM_ABI inline uint64_t __ryu_shiftright128(const uint64_t __lo, const uint64_t __hi, const uint32_t __dist) {
+  // For the __shiftright128 intrinsic, the shift value is always
+  // modulo 64.
+  // In the current implementation of the double-precision version
+  // of Ryu, the shift value is always < 64.
+  // (The shift value is in the range [49, 58].)
+  // Check this here in case a future change requires larger shift
+  // values. In this case this function needs to be adjusted.
+  _LIBCPP_ASSERT(__dist < 64, "");
+  return __shiftright128(__lo, __hi, static_cast<unsigned char>(__dist));
+}
+
+// ^^^ intrinsics available ^^^ / vvv __int128 available vvv
+#elif defined(__SIZEOF_INT128__) && ( \
+    (defined(__clang__) && !defined(_MSC_VER)) || \
+    (defined(__GNUC__) && !defined(__clang__) && !defined(__CUDACC__)))
+#define _LIBCPP_INTRINSIC128 1
+  // We have __uint128 support in clang or gcc
+[[nodiscard]] _LIBCPP_HIDE_FROM_ABI inline uint64_t __ryu_umul128(const uint64_t __a, const uint64_t __b, uint64_t* const __productHi) {
+  auto __temp = __a * (unsigned __int128)__b;
+  *__productHi = __temp >> 64;
+  return static_cast<uint64_t>(__temp);
+}
+
+[[nodiscard]] _LIBCPP_HIDE_FROM_ABI inline uint64_t __ryu_shiftright128(const uint64_t __lo, const uint64_t __hi, const uint32_t __dist) {
+  // In the current implementation of the double-precision version
+  // of Ryu, the shift value is always < 64.
+  // (The shift value is in the range [49, 58].)
+  // Check this here in case a future change requires larger shift
+  // values. In this case this function needs to be adjusted.
+  _LIBCPP_ASSERT(__dist < 64, "");
+  auto __temp = __lo | ((unsigned __int128)__hi << 64);
+  // For x64 128-bit shfits using the `shrd` instruction and two 64-bit
+  // registers, the shift value is modulo 64.  Thus the `& 63` is free.
+  return static_cast<uint64_t>(__temp >> (__dist & 63));
+}
+#else // ^^^ __int128 available ^^^ / vvv intrinsics unavailable vvv
+
+[[nodiscard]] _LIBCPP_HIDE_FROM_ABI inline _LIBCPP_ALWAYS_INLINE uint64_t __ryu_umul128(const uint64_t __a, const uint64_t __b, uint64_t* const __productHi) {
+  // TRANSITION, VSO-634761
+  // The casts here help MSVC to avoid calls to the __allmul library function.
+  const uint32_t __aLo = static_cast<uint32_t>(__a);
+  const uint32_t __aHi = static_cast<uint32_t>(__a >> 32);
+  const uint32_t __bLo = static_cast<uint32_t>(__b);
+  const uint32_t __bHi = static_cast<uint32_t>(__b >> 32);
+
+  const uint64_t __b00 = static_cast<uint64_t>(__aLo) * __bLo;
+  const uint64_t __b01 = static_cast<uint64_t>(__aLo) * __bHi;
+  const uint64_t __b10 = static_cast<uint64_t>(__aHi) * __bLo;
+  const uint64_t __b11 = static_cast<uint64_t>(__aHi) * __bHi;
+
+  const uint32_t __b00Lo = static_cast<uint32_t>(__b00);
+  const uint32_t __b00Hi = static_cast<uint32_t>(__b00 >> 32);
+
+  const uint64_t __mid1 = __b10 + __b00Hi;
+  const uint32_t __mid1Lo = static_cast<uint32_t>(__mid1);
+  const uint32_t __mid1Hi = static_cast<uint32_t>(__mid1 >> 32);
+
+  const uint64_t __mid2 = __b01 + __mid1Lo;
+  const uint32_t __mid2Lo = static_cast<uint32_t>(__mid2);
+  const uint32_t __mid2Hi = static_cast<uint32_t>(__mid2 >> 32);
+
+  const uint64_t __pHi = __b11 + __mid1Hi + __mid2Hi;
+  const uint64_t __pLo = (static_cast<uint64_t>(__mid2Lo) << 32) | __b00Lo;
+
+  *__productHi = __pHi;
+  return __pLo;
+}
+
+[[nodiscard]] _LIBCPP_HIDE_FROM_ABI inline uint64_t __ryu_shiftright128(const uint64_t __lo, const uint64_t __hi, const uint32_t __dist) {
+  // We don't need to handle the case __dist >= 64 here (see above).
+  _LIBCPP_ASSERT(__dist < 64, "");
+#ifdef _LIBCPP_64_BIT
+  _LIBCPP_ASSERT(__dist > 0, "");
+  return (__hi << (64 - __dist)) | (__lo >> __dist);
+#else // ^^^ 64-bit ^^^ / vvv 32-bit vvv
+  // Avoid a 64-bit shift by taking advantage of the range of shift values.
+  _LIBCPP_ASSERT(__dist >= 32, "");
+  return (__hi << (64 - __dist)) | (static_cast<uint32_t>(__lo >> 32) >> (__dist - 32));
+#endif // ^^^ 32-bit ^^^
+}
+
+#endif // ^^^ intrinsics unavailable ^^^
+
+#ifndef _LIBCPP_64_BIT
+
+// Returns the high 64 bits of the 128-bit product of __a and __b.
+[[nodiscard]] _LIBCPP_HIDE_FROM_ABI inline uint64_t __umulh(const uint64_t __a, const uint64_t __b) {
+  // Reuse the __ryu_umul128 implementation.
+  // Optimizers will likely eliminate the instructions used to compute the
+  // low part of the product.
+  uint64_t __hi;
+  (void) __ryu_umul128(__a, __b, &__hi);
+  return __hi;
+}
+
+// On 32-bit platforms, compilers typically generate calls to library
+// functions for 64-bit divisions, even if the divisor is a constant.
+//
+// TRANSITION, LLVM-37932
+//
+// The functions here perform division-by-constant using multiplications
+// in the same way as 64-bit compilers would do.
+//
+// NB:
+// The multipliers and shift values are the ones generated by clang x64
+// for expressions like x/5, x/10, etc.
+
+[[nodiscard]] _LIBCPP_HIDE_FROM_ABI inline uint64_t __div5(const uint64_t __x) {
+  return __umulh(__x, 0xCCCCCCCCCCCCCCCDu) >> 2;
+}
+
+[[nodiscard]] _LIBCPP_HIDE_FROM_ABI inline uint64_t __div10(const uint64_t __x) {
+  return __umulh(__x, 0xCCCCCCCCCCCCCCCDu) >> 3;
+}
+
+[[nodiscard]] _LIBCPP_HIDE_FROM_ABI inline uint64_t __div100(const uint64_t __x) {
+  return __umulh(__x >> 2, 0x28F5C28F5C28F5C3u) >> 2;
+}
+
+[[nodiscard]] _LIBCPP_HIDE_FROM_ABI inline uint64_t __div1e8(const uint64_t __x) {
+  return __umulh(__x, 0xABCC77118461CEFDu) >> 26;
+}
+
+[[nodiscard]] _LIBCPP_HIDE_FROM_ABI inline uint64_t __div1e9(const uint64_t __x) {
+  return __umulh(__x >> 9, 0x44B82FA09B5A53u) >> 11;
+}
+
+[[nodiscard]] _LIBCPP_HIDE_FROM_ABI inline uint32_t __mod1e9(const uint64_t __x) {
+  // Avoid 64-bit math as much as possible.
+  // Returning static_cast<uint32_t>(__x - 1000000000 * __div1e9(__x)) would
+  // perform 32x64-bit multiplication and 64-bit subtraction.
+  // __x and 1000000000 * __div1e9(__x) are guaranteed to differ by
+  // less than 10^9, so their highest 32 bits must be identical,
+  // so we can truncate both sides to uint32_t before subtracting.
+  // We can also simplify static_cast<uint32_t>(1000000000 * __div1e9(__x)).
+  // We can truncate before multiplying instead of after, as multiplying
+  // the highest 32 bits of __div1e9(__x) can't affect the lowest 32 bits.
+  return static_cast<uint32_t>(__x) - 1000000000 * static_cast<uint32_t>(__div1e9(__x));
+}
+
+#else // ^^^ 32-bit ^^^ / vvv 64-bit vvv
+
+[[nodiscard]] _LIBCPP_HIDE_FROM_ABI inline uint64_t __div5(const uint64_t __x) {
+  return __x / 5;
+}
+
+[[nodiscard]] _LIBCPP_HIDE_FROM_ABI inline uint64_t __div10(const uint64_t __x) {
+  return __x / 10;
+}
+
+[[nodiscard]] _LIBCPP_HIDE_FROM_ABI inline uint64_t __div100(const uint64_t __x) {
+  return __x / 100;
+}
+
+[[nodiscard]] _LIBCPP_HIDE_FROM_ABI inline uint64_t __div1e8(const uint64_t __x) {
+  return __x / 100000000;
+}
+
+[[nodiscard]] _LIBCPP_HIDE_FROM_ABI inline uint64_t __div1e9(const uint64_t __x) {
+  return __x / 1000000000;
+}
+
+[[nodiscard]] _LIBCPP_HIDE_FROM_ABI inline uint32_t __mod1e9(const uint64_t __x) {
+  return static_cast<uint32_t>(__x - 1000000000 * __div1e9(__x));
+}
+
+#endif // ^^^ 64-bit ^^^
+
+[[nodiscard]] _LIBCPP_HIDE_FROM_ABI inline uint32_t __pow5Factor(uint64_t __value) {
+  uint32_t __count = 0;
+  for (;;) {
+    _LIBCPP_ASSERT(__value != 0, "");
+    const uint64_t __q = __div5(__value);
+    const uint32_t __r = static_cast<uint32_t>(__value) - 5 * static_cast<uint32_t>(__q);
+    if (__r != 0) {
+      break;
+    }
+    __value = __q;
+    ++__count;
+  }
+  return __count;
+}
+
+// Returns true if __value is divisible by 5^__p.
+[[nodiscard]] _LIBCPP_HIDE_FROM_ABI inline bool __multipleOfPowerOf5(const uint64_t __value, const uint32_t __p) {
+  // I tried a case distinction on __p, but there was no performance difference.
+  return __pow5Factor(__value) >= __p;
+}
+
+// Returns true if __value is divisible by 2^__p.
+[[nodiscard]] _LIBCPP_HIDE_FROM_ABI inline bool __multipleOfPowerOf2(const uint64_t __value, const uint32_t __p) {
+  _LIBCPP_ASSERT(__value != 0, "");
+  _LIBCPP_ASSERT(__p < 64, "");
+  // __builtin_ctzll doesn't appear to be faster here.
+  return (__value & ((1ull << __p) - 1)) == 0;
+}
+
+_LIBCPP_END_NAMESPACE_STD
+
+// clang-format on
+
+#endif // _LIBCPP_SRC_INCLUDE_RYU_DS2_INTRINSICS_H

third_party/libcxx/src/include/ryu/digit_table.h

@@ -0,0 +1,57 @@
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+// Copyright (c) Microsoft Corporation.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+
+// Copyright 2018 Ulf Adams
+// Copyright (c) Microsoft Corporation. All rights reserved.
+
+// Boost Software License - Version 1.0 - August 17th, 2003
+
+// Permission is hereby granted, free of charge, to any person or organization
+// obtaining a copy of the software and accompanying documentation covered by
+// this license (the "Software") to use, reproduce, display, distribute,
+// execute, and transmit the Software, and to prepare derivative works of the
+// Software, and to permit third-parties to whom the Software is furnished to
+// do so, all subject to the following:
+
+// The copyright notices in the Software and this entire statement, including
+// the above license grant, this restriction and the following disclaimer,
+// must be included in all copies of the Software, in whole or in part, and
+// all derivative works of the Software, unless such copies or derivative
+// works are solely in the form of machine-executable object code generated by
+// a source language processor.
+
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+// FITNESS FOR A PARTICULAR PURPOSE, TITLE AND NON-INFRINGEMENT. IN NO EVENT
+// SHALL THE COPYRIGHT HOLDERS OR ANYONE DISTRIBUTING THE SOFTWARE BE LIABLE
+// FOR ANY DAMAGES OR OTHER LIABILITY, WHETHER IN CONTRACT, TORT OR OTHERWISE,
+// ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
+// DEALINGS IN THE SOFTWARE.
+
+#ifndef _LIBCPP_SRC_INCLUDE_RYU_DIGIT_TABLE_H
+#define _LIBCPP_SRC_INCLUDE_RYU_DIGIT_TABLE_H
+
+#include <__charconv/tables.h>
+#include <__config>
+
+_LIBCPP_BEGIN_NAMESPACE_STD
+
+// A table of all two-digit numbers. This is used to speed up decimal digit
+// generation by copying pairs of digits into the final output.
+//
+// In order to minimize the diff in the Ryu code between MSVC STL and libc++
+// the code uses the name __DIGIT_TABLE. In order to avoid code duplication it
+// reuses the table already available in libc++.
+inline constexpr auto& __DIGIT_TABLE = __itoa::__digits_base_10;
+
+_LIBCPP_END_NAMESPACE_STD
+
+#endif // _LIBCPP_SRC_INCLUDE_RYU_DIGIT_TABLE_H

third_party/libcxx/src/include/ryu/f2s.h

@@ -0,0 +1,55 @@
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+// Copyright (c) Microsoft Corporation.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+
+// Copyright 2018 Ulf Adams
+// Copyright (c) Microsoft Corporation. All rights reserved.
+
+// Boost Software License - Version 1.0 - August 17th, 2003
+
+// Permission is hereby granted, free of charge, to any person or organization
+// obtaining a copy of the software and accompanying documentation covered by
+// this license (the "Software") to use, reproduce, display, distribute,
+// execute, and transmit the Software, and to prepare derivative works of the
+// Software, and to permit third-parties to whom the Software is furnished to
+// do so, all subject to the following:
+
+// The copyright notices in the Software and this entire statement, including
+// the above license grant, this restriction and the following disclaimer,
+// must be included in all copies of the Software, in whole or in part, and
+// all derivative works of the Software, unless such copies or derivative
+// works are solely in the form of machine-executable object code generated by
+// a source language processor.
+
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+// FITNESS FOR A PARTICULAR PURPOSE, TITLE AND NON-INFRINGEMENT. IN NO EVENT
+// SHALL THE COPYRIGHT HOLDERS OR ANYONE DISTRIBUTING THE SOFTWARE BE LIABLE
+// FOR ANY DAMAGES OR OTHER LIABILITY, WHETHER IN CONTRACT, TORT OR OTHERWISE,
+// ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
+// DEALINGS IN THE SOFTWARE.
+
+#ifndef _LIBCPP_SRC_INCLUDE_RYU_FS2_H
+#define _LIBCPP_SRC_INCLUDE_RYU_FS2_H
+
+// Avoid formatting to keep the changes with the original code minimal.
+// clang-format off
+
+#include <__config>
+
+_LIBCPP_BEGIN_NAMESPACE_STD
+
+[[nodiscard]] to_chars_result __f2s_buffered_n(char* const _First, char* const _Last, const float __f, const chars_format _Fmt);
+
+_LIBCPP_END_NAMESPACE_STD
+
+// clang-format on
+
+#endif // _LIBCPP_SRC_INCLUDE_RYU_FS2_H

third_party/libcxx/src/include/ryu/ryu.h

@@ -0,0 +1,149 @@
+// -*- C++ -*-
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+// Copyright (c) Microsoft Corporation.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+
+
+// Copyright 2018 Ulf Adams
+// Copyright (c) Microsoft Corporation. All rights reserved.
+
+// Boost Software License - Version 1.0 - August 17th, 2003
+
+// Permission is hereby granted, free of charge, to any person or organization
+// obtaining a copy of the software and accompanying documentation covered by
+// this license (the "Software") to use, reproduce, display, distribute,
+// execute, and transmit the Software, and to prepare derivative works of the
+// Software, and to permit third-parties to whom the Software is furnished to
+// do so, all subject to the following:
+
+// The copyright notices in the Software and this entire statement, including
+// the above license grant, this restriction and the following disclaimer,
+// must be included in all copies of the Software, in whole or in part, and
+// all derivative works of the Software, unless such copies or derivative
+// works are solely in the form of machine-executable object code generated by
+// a source language processor.
+
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+// FITNESS FOR A PARTICULAR PURPOSE, TITLE AND NON-INFRINGEMENT. IN NO EVENT
+// SHALL THE COPYRIGHT HOLDERS OR ANYONE DISTRIBUTING THE SOFTWARE BE LIABLE
+// FOR ANY DAMAGES OR OTHER LIABILITY, WHETHER IN CONTRACT, TORT OR OTHERWISE,
+// ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
+// DEALINGS IN THE SOFTWARE.
+
+#ifndef _LIBCPP_SRC_INCLUDE_RYU_RYU_H
+#define _LIBCPP_SRC_INCLUDE_RYU_RYU_H
+
+// Avoid formatting to keep the changes with the original code minimal.
+// clang-format off
+
+#include <__charconv/chars_format.h>
+#include <__charconv/to_chars_result.h>
+#include <__config>
+#include <__debug>
+#include <__system_error/errc.h>
+#include <cstdint>
+#include <cstring>
+#include <type_traits>
+
+#include "third_party/libcxx/src/include/ryu/f2s.h"
+#include "third_party/libcxx/src/include/ryu/d2s.h"
+#include "third_party/libcxx/src/include/ryu/d2fixed.h"
+
+#if defined(_MSC_VER)
+#include <intrin.h> // for _umul128(), __shiftright128(), _BitScanForward{,64}
+#endif // defined(_MSC_VER)
+
+#if defined(_WIN64) || defined(_M_AMD64) || defined(__x86_64__) ||  defined(__aarch64__)
+#define _LIBCPP_64_BIT
+#endif
+
+_LIBCPP_BEGIN_NAMESPACE_STD
+
+// https://github.com/ulfjack/ryu/tree/59661c3/ryu
+
+#if !defined(_MSC_VER)
+_LIBCPP_HIDE_FROM_ABI inline unsigned char _BitScanForward64(unsigned long* __index, unsigned long long __mask) {
+  if (__mask == 0) {
+    return false;
+  }
+  *__index = __builtin_ctzll(__mask);
+  return true;
+}
+
+_LIBCPP_HIDE_FROM_ABI inline unsigned char _BitScanForward(unsigned long* __index, unsigned int __mask) {
+  if (__mask == 0) {
+    return false;
+  }
+  *__index = __builtin_ctz(__mask);
+  return true;
+}
+#endif  // !_MSC_VER
+
+template <class _Floating>
+[[nodiscard]] to_chars_result _Floating_to_chars_ryu(
+    char* const _First, char* const _Last, const _Floating _Value, const chars_format _Fmt) noexcept {
+    if constexpr (_IsSame<_Floating, float>::value) {
+        return __f2s_buffered_n(_First, _Last, _Value, _Fmt);
+    } else {
+        return __d2s_buffered_n(_First, _Last, _Value, _Fmt);
+    }
+}
+
+template <class _Floating>
+[[nodiscard]] _LIBCPP_HIDE_FROM_ABI to_chars_result _Floating_to_chars_scientific_precision(
+    char* const _First, char* const _Last, const _Floating _Value, int _Precision) noexcept {
+
+    // C11 7.21.6.1 "The fprintf function"/5:
+    // "A negative precision argument is taken as if the precision were omitted."
+    // /8: "e,E [...] if the precision is missing, it is taken as 6"
+
+    if (_Precision < 0) {
+        _Precision = 6;
+    } else if (_Precision < 1'000'000'000) { // Match ' to fix compilation with GCC in C++11 mode
+        // _Precision is ok.
+    } else {
+        // Avoid integer overflow.
+        // (This defensive check is slightly nonconformant; it can be carefully improved in the future.)
+        return {_Last, errc::value_too_large};
+    }
+
+    return __d2exp_buffered_n(_First, _Last, _Value, static_cast<uint32_t>(_Precision));
+}
+
+template <class _Floating>
+[[nodiscard]] _LIBCPP_HIDE_FROM_ABI to_chars_result _Floating_to_chars_fixed_precision(
+    char* const _First, char* const _Last, const _Floating _Value, int _Precision) noexcept {
+
+    // C11 7.21.6.1 "The fprintf function"/5:
+    // "A negative precision argument is taken as if the precision were omitted."
+    // /8: "f,F [...] If the precision is missing, it is taken as 6"
+
+    if (_Precision < 0) {
+        _Precision = 6;
+    } else if (_Precision < 1'000'000'000) { // Match ' to fix compilation with GCC in C++11 mode
+        // _Precision is ok.
+    } else {
+        // Avoid integer overflow.
+        // (This defensive check is slightly nonconformant; it can be carefully improved in the future.)
+        return {_Last, errc::value_too_large};
+    }
+
+    return __d2fixed_buffered_n(_First, _Last, _Value, static_cast<uint32_t>(_Precision));
+}
+
+#undef _LIBCPP_64_BIT
+#undef _LIBCPP_INTRINSIC128
+
+_LIBCPP_END_NAMESPACE_STD
+
+// clang-format on
+
+#endif // _LIBCPP_SRC_INCLUDE_RYU_RYU_H

third_party/libcxx/src/include/sso_allocator.h

@@ -0,0 +1,82 @@
+// -*- C++ -*-
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef _LIBCPP_SSO_ALLOCATOR_H
+#define _LIBCPP_SSO_ALLOCATOR_H
+
+#include <__config>
+#include <memory>
+#include <new>
+#include <type_traits>
+
+#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
+#pragma GCC system_header
+#endif
+
+_LIBCPP_BEGIN_NAMESPACE_STD
+
+template <class _Tp, size_t _Np> class _LIBCPP_HIDDEN __sso_allocator;
+
+template <size_t _Np>
+class _LIBCPP_HIDDEN __sso_allocator<void, _Np>
+{
+public:
+    typedef const void*       const_pointer;
+    typedef void              value_type;
+};
+
+template <class _Tp, size_t _Np>
+class _LIBCPP_HIDDEN __sso_allocator
+{
+    typename aligned_storage<sizeof(_Tp) * _Np>::type buf_;
+    bool __allocated_;
+public:
+    typedef size_t            size_type;
+    typedef _Tp*              pointer;
+    typedef _Tp               value_type;
+
+    template <class U>
+    struct rebind {
+        using other = __sso_allocator<U, _Np>;
+    };
+
+    _LIBCPP_INLINE_VISIBILITY __sso_allocator() throw() : __allocated_(false) {}
+    _LIBCPP_INLINE_VISIBILITY __sso_allocator(const __sso_allocator&) throw() : __allocated_(false) {}
+    template <class _Up> _LIBCPP_INLINE_VISIBILITY __sso_allocator(const __sso_allocator<_Up, _Np>&) throw()
+         : __allocated_(false) {}
+private:
+    __sso_allocator& operator=(const __sso_allocator&);
+public:
+    _LIBCPP_INLINE_VISIBILITY pointer allocate(size_type __n, typename __sso_allocator<void, _Np>::const_pointer = nullptr)
+    {
+        if (!__allocated_ && __n <= _Np)
+        {
+            __allocated_ = true;
+            return (pointer)&buf_;
+        }
+        return allocator<_Tp>().allocate(__n);
+    }
+    _LIBCPP_INLINE_VISIBILITY void deallocate(pointer __p, size_type __n)
+    {
+        if (__p == (pointer)&buf_)
+            __allocated_ = false;
+        else
+            allocator<_Tp>().deallocate(__p, __n);
+    }
+    _LIBCPP_INLINE_VISIBILITY size_type max_size() const throw() {return size_type(~0) / sizeof(_Tp);}
+
+    _LIBCPP_INLINE_VISIBILITY
+    bool operator==(const __sso_allocator& __a) const {return &buf_ == &__a.buf_;}
+    _LIBCPP_INLINE_VISIBILITY
+    bool operator!=(const __sso_allocator& __a) const {return &buf_ != &__a.buf_;}
+};
+
+_LIBCPP_END_NAMESPACE_STD
+
+#endif // _LIBCPP_SSO_ALLOCATOR_H

third_party/libcxx/src/ios.cpp

@@ -0,0 +1,443 @@
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#include <__config>
+#include <__locale>
+#include <algorithm>
+#include <ios>
+#include <limits>
+#include <memory>
+#include <new>
+#include <stdlib.h>
+#include <string>
+
+#include "third_party/libcxx/src/include/config_elast.h"
+
+_LIBCPP_PUSH_MACROS
+#include <__undef_macros>
+
+_LIBCPP_BEGIN_NAMESPACE_STD
+
+class _LIBCPP_HIDDEN __iostream_category
+    : public __do_message
+{
+public:
+    virtual const char* name() const noexcept;
+    virtual string message(int ev) const;
+};
+
+const char*
+__iostream_category::name() const noexcept
+{
+    return "iostream";
+}
+
+string
+__iostream_category::message(int ev) const
+{
+    if (ev != static_cast<int>(io_errc::stream)
+#ifdef _LIBCPP_ELAST
+        && ev <= _LIBCPP_ELAST
+#endif // _LIBCPP_ELAST
+        )
+        return __do_message::message(ev);
+    return string("unspecified iostream_category error");
+}
+
+const error_category&
+iostream_category() noexcept
+{
+    static __iostream_category s;
+    return s;
+}
+
+// ios_base::failure
+
+ios_base::failure::failure(const string& msg, const error_code& ec)
+    : system_error(ec, msg)
+{
+}
+
+ios_base::failure::failure(const char* msg, const error_code& ec)
+    : system_error(ec, msg)
+{
+}
+
+ios_base::failure::~failure() throw()
+{
+}
+
+// ios_base locale
+
+const ios_base::fmtflags ios_base::boolalpha;
+const ios_base::fmtflags ios_base::dec;
+const ios_base::fmtflags ios_base::fixed;
+const ios_base::fmtflags ios_base::hex;
+const ios_base::fmtflags ios_base::internal;
+const ios_base::fmtflags ios_base::left;
+const ios_base::fmtflags ios_base::oct;
+const ios_base::fmtflags ios_base::right;
+const ios_base::fmtflags ios_base::scientific;
+const ios_base::fmtflags ios_base::showbase;
+const ios_base::fmtflags ios_base::showpoint;
+const ios_base::fmtflags ios_base::showpos;
+const ios_base::fmtflags ios_base::skipws;
+const ios_base::fmtflags ios_base::unitbuf;
+const ios_base::fmtflags ios_base::uppercase;
+const ios_base::fmtflags ios_base::adjustfield;
+const ios_base::fmtflags ios_base::basefield;
+const ios_base::fmtflags ios_base::floatfield;
+
+const ios_base::iostate ios_base::badbit;
+const ios_base::iostate ios_base::eofbit;
+const ios_base::iostate ios_base::failbit;
+const ios_base::iostate ios_base::goodbit;
+
+const ios_base::openmode ios_base::app;
+const ios_base::openmode ios_base::ate;
+const ios_base::openmode ios_base::binary;
+const ios_base::openmode ios_base::in;
+const ios_base::openmode ios_base::out;
+const ios_base::openmode ios_base::trunc;
+
+void
+ios_base::__call_callbacks(event ev)
+{
+    for (size_t i = __event_size_; i;)
+    {
+        --i;
+        __fn_[i](ev, *this, __index_[i]);
+    }
+}
+
+// locale
+
+locale
+ios_base::imbue(const locale& newloc)
+{
+    static_assert(sizeof(locale) == sizeof(__loc_), "");
+    locale& loc_storage = *reinterpret_cast<locale*>(&__loc_);
+    locale oldloc = loc_storage;
+    loc_storage = newloc;
+    __call_callbacks(imbue_event);
+    return oldloc;
+}
+
+locale
+ios_base::getloc() const
+{
+    const locale& loc_storage = *reinterpret_cast<const locale*>(&__loc_);
+    return loc_storage;
+}
+
+// xalloc
+#if defined(_LIBCPP_HAS_C_ATOMIC_IMP) && !defined(_LIBCPP_HAS_NO_THREADS)
+atomic<int> ios_base::__xindex_{0};
+#else
+int ios_base::__xindex_ = 0;
+#endif
+
+template <typename _Tp>
+static size_t __ios_new_cap(size_t __req_size, size_t __current_cap)
+{ // Precondition: __req_size > __current_cap
+    const size_t mx = std::numeric_limits<size_t>::max() / sizeof(_Tp);
+    if (__req_size < mx/2)
+        return _VSTD::max(2 * __current_cap, __req_size);
+    else
+        return mx;
+}
+
+int
+ios_base::xalloc()
+{
+    return __xindex_++;
+}
+
+long&
+ios_base::iword(int index)
+{
+    size_t req_size = static_cast<size_t>(index)+1;
+    if (req_size > __iarray_cap_)
+    {
+        size_t newcap = __ios_new_cap<long>(req_size, __iarray_cap_);
+        long* iarray = static_cast<long*>(realloc(__iarray_, newcap * sizeof(long)));
+        if (iarray == 0)
+        {
+            setstate(badbit);
+            static long error;
+            error = 0;
+            return error;
+        }
+        __iarray_ = iarray;
+        for (long* p = __iarray_ + __iarray_size_; p < __iarray_ + newcap; ++p)
+            *p = 0;
+        __iarray_cap_ = newcap;
+    }
+    __iarray_size_ = max<size_t>(__iarray_size_, req_size);
+    return __iarray_[index];
+}
+
+void*&
+ios_base::pword(int index)
+{
+    size_t req_size = static_cast<size_t>(index)+1;
+    if (req_size > __parray_cap_)
+    {
+        size_t newcap = __ios_new_cap<void *>(req_size, __iarray_cap_);
+        void** parray = static_cast<void**>(realloc(__parray_, newcap * sizeof(void *)));
+        if (parray == 0)
+        {
+            setstate(badbit);
+            static void* error;
+            error = 0;
+            return error;
+        }
+        __parray_ = parray;
+        for (void** p = __parray_ + __parray_size_; p < __parray_ + newcap; ++p)
+            *p = 0;
+        __parray_cap_ = newcap;
+    }
+    __parray_size_ = max<size_t>(__parray_size_, req_size);
+    return __parray_[index];
+}
+
+// register_callback
+
+void
+ios_base::register_callback(event_callback fn, int index)
+{
+    size_t req_size = __event_size_ + 1;
+    if (req_size > __event_cap_)
+    {
+        size_t newcap = __ios_new_cap<event_callback>(req_size, __event_cap_);
+        event_callback* fns = static_cast<event_callback*>(realloc(__fn_, newcap * sizeof(event_callback)));
+        if (fns == 0)
+            setstate(badbit);
+        __fn_ = fns;
+        int* indxs = static_cast<int *>(realloc(__index_, newcap * sizeof(int)));
+        if (indxs == 0)
+            setstate(badbit);
+        __index_ = indxs;
+        __event_cap_ = newcap;
+    }
+    __fn_[__event_size_] = fn;
+    __index_[__event_size_] = index;
+    ++__event_size_;
+}
+
+ios_base::~ios_base()
+{
+    __call_callbacks(erase_event);
+    locale& loc_storage = *reinterpret_cast<locale*>(&__loc_);
+    loc_storage.~locale();
+    free(__fn_);
+    free(__index_);
+    free(__iarray_);
+    free(__parray_);
+}
+
+// iostate
+
+void
+ios_base::clear(iostate state)
+{
+    if (__rdbuf_)
+        __rdstate_ = state;
+    else
+        __rdstate_ = state | badbit;
+
+    if (((state | (__rdbuf_ ? goodbit : badbit)) & __exceptions_) != 0)
+        __throw_failure("ios_base::clear");
+}
+
+// init
+
+void
+ios_base::init(void* sb)
+{
+    __rdbuf_ = sb;
+    __rdstate_ = __rdbuf_ ? goodbit : badbit;
+    __exceptions_ = goodbit;
+    __fmtflags_ = skipws | dec;
+    __width_ = 0;
+    __precision_ = 6;
+    __fn_ = 0;
+    __index_ = 0;
+    __event_size_ = 0;
+    __event_cap_ = 0;
+    __iarray_ = 0;
+    __iarray_size_ = 0;
+    __iarray_cap_ = 0;
+    __parray_ = 0;
+    __parray_size_ = 0;
+    __parray_cap_ = 0;
+    ::new(&__loc_) locale;
+}
+
+void
+ios_base::copyfmt(const ios_base& rhs)
+{
+    // If we can't acquire the needed resources, throw bad_alloc (can't set badbit)
+    // Don't alter *this until all needed resources are acquired
+    unique_ptr<event_callback, void (*)(void*)> new_callbacks(0, free);
+    unique_ptr<int, void (*)(void*)> new_ints(0, free);
+    unique_ptr<long, void (*)(void*)> new_longs(0, free);
+    unique_ptr<void*, void (*)(void*)> new_pointers(0, free);
+    if (__event_cap_ < rhs.__event_size_)
+    {
+        size_t newesize = sizeof(event_callback) * rhs.__event_size_;
+        new_callbacks.reset(static_cast<event_callback*>(malloc(newesize)));
+        if (!new_callbacks)
+            __throw_bad_alloc();
+
+        size_t newisize = sizeof(int) * rhs.__event_size_;
+        new_ints.reset(static_cast<int *>(malloc(newisize)));
+        if (!new_ints)
+            __throw_bad_alloc();
+    }
+    if (__iarray_cap_ < rhs.__iarray_size_)
+    {
+        size_t newsize = sizeof(long) * rhs.__iarray_size_;
+        new_longs.reset(static_cast<long*>(malloc(newsize)));
+        if (!new_longs)
+            __throw_bad_alloc();
+    }
+    if (__parray_cap_ < rhs.__parray_size_)
+    {
+        size_t newsize = sizeof(void*) * rhs.__parray_size_;
+        new_pointers.reset(static_cast<void**>(malloc(newsize)));
+        if (!new_pointers)
+            __throw_bad_alloc();
+    }
+    // Got everything we need.  Copy everything but __rdstate_, __rdbuf_ and __exceptions_
+    __fmtflags_ = rhs.__fmtflags_;
+    __precision_ = rhs.__precision_;
+    __width_ = rhs.__width_;
+    locale& lhs_loc = *reinterpret_cast<locale*>(&__loc_);
+    const locale& rhs_loc = *reinterpret_cast<const locale*>(&rhs.__loc_);
+    lhs_loc = rhs_loc;
+    if (__event_cap_ < rhs.__event_size_)
+    {
+        free(__fn_);
+        __fn_ = new_callbacks.release();
+        free(__index_);
+        __index_ = new_ints.release();
+        __event_cap_ = rhs.__event_size_;
+    }
+    for (__event_size_ = 0; __event_size_ < rhs.__event_size_; ++__event_size_)
+    {
+        __fn_[__event_size_] = rhs.__fn_[__event_size_];
+        __index_[__event_size_] = rhs.__index_[__event_size_];
+    }
+    if (__iarray_cap_ < rhs.__iarray_size_)
+    {
+        free(__iarray_);
+        __iarray_ = new_longs.release();
+        __iarray_cap_ = rhs.__iarray_size_;
+    }
+    for (__iarray_size_ = 0; __iarray_size_ < rhs.__iarray_size_; ++__iarray_size_)
+        __iarray_[__iarray_size_] = rhs.__iarray_[__iarray_size_];
+    if (__parray_cap_ < rhs.__parray_size_)
+    {
+        free(__parray_);
+        __parray_ = new_pointers.release();
+        __parray_cap_ = rhs.__parray_size_;
+    }
+    for (__parray_size_ = 0; __parray_size_ < rhs.__parray_size_; ++__parray_size_)
+        __parray_[__parray_size_] = rhs.__parray_[__parray_size_];
+}
+
+void
+ios_base::move(ios_base& rhs)
+{
+    // *this is uninitialized
+    __fmtflags_ = rhs.__fmtflags_;
+    __precision_ = rhs.__precision_;
+    __width_ = rhs.__width_;
+    __rdstate_ = rhs.__rdstate_;
+    __exceptions_ = rhs.__exceptions_;
+    __rdbuf_ = 0;
+    locale& rhs_loc = *reinterpret_cast<locale*>(&rhs.__loc_);
+    ::new(&__loc_) locale(rhs_loc);
+    __fn_ = rhs.__fn_;
+    rhs.__fn_ = 0;
+    __index_ = rhs.__index_;
+    rhs.__index_ = 0;
+    __event_size_ = rhs.__event_size_;
+    rhs.__event_size_ = 0;
+    __event_cap_ = rhs.__event_cap_;
+    rhs.__event_cap_ = 0;
+    __iarray_ = rhs.__iarray_;
+    rhs.__iarray_ = 0;
+    __iarray_size_ = rhs.__iarray_size_;
+    rhs.__iarray_size_ = 0;
+    __iarray_cap_ = rhs.__iarray_cap_;
+    rhs.__iarray_cap_ = 0;
+    __parray_ = rhs.__parray_;
+    rhs.__parray_ = 0;
+    __parray_size_ = rhs.__parray_size_;
+    rhs.__parray_size_ = 0;
+    __parray_cap_ = rhs.__parray_cap_;
+    rhs.__parray_cap_ = 0;
+}
+
+void
+ios_base::swap(ios_base& rhs) noexcept
+{
+    _VSTD::swap(__fmtflags_, rhs.__fmtflags_);
+    _VSTD::swap(__precision_, rhs.__precision_);
+    _VSTD::swap(__width_, rhs.__width_);
+    _VSTD::swap(__rdstate_, rhs.__rdstate_);
+    _VSTD::swap(__exceptions_, rhs.__exceptions_);
+    locale& lhs_loc = *reinterpret_cast<locale*>(&__loc_);
+    locale& rhs_loc = *reinterpret_cast<locale*>(&rhs.__loc_);
+    _VSTD::swap(lhs_loc, rhs_loc);
+    _VSTD::swap(__fn_, rhs.__fn_);
+    _VSTD::swap(__index_, rhs.__index_);
+    _VSTD::swap(__event_size_, rhs.__event_size_);
+    _VSTD::swap(__event_cap_, rhs.__event_cap_);
+    _VSTD::swap(__iarray_, rhs.__iarray_);
+    _VSTD::swap(__iarray_size_, rhs.__iarray_size_);
+    _VSTD::swap(__iarray_cap_, rhs.__iarray_cap_);
+    _VSTD::swap(__parray_, rhs.__parray_);
+    _VSTD::swap(__parray_size_, rhs.__parray_size_);
+    _VSTD::swap(__parray_cap_, rhs.__parray_cap_);
+}
+
+void
+ios_base::__set_badbit_and_consider_rethrow()
+{
+    __rdstate_ |= badbit;
+#ifndef _LIBCPP_HAS_NO_EXCEPTIONS
+    if (__exceptions_ & badbit)
+        throw;
+#endif // _LIBCPP_HAS_NO_EXCEPTIONS
+}
+
+void
+ios_base::__set_failbit_and_consider_rethrow()
+{
+    __rdstate_ |= failbit;
+#ifndef _LIBCPP_HAS_NO_EXCEPTIONS
+    if (__exceptions_ & failbit)
+        throw;
+#endif // _LIBCPP_HAS_NO_EXCEPTIONS
+}
+
+bool
+ios_base::sync_with_stdio(bool sync)
+{
+    static bool previous_state = true;
+    bool r = previous_state;
+    previous_state = sync;
+    return r;
+}
+
+_LIBCPP_END_NAMESPACE_STD
+
+_LIBCPP_POP_MACROS

third_party/libcxx/src/ios.instantiations.cpp

@@ -0,0 +1,48 @@
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#include <__config>
+#include <fstream>
+#include <ios>
+#include <istream>
+#include <ostream>
+#include <sstream>
+#include <streambuf>
+
+_LIBCPP_BEGIN_NAMESPACE_STD
+
+// Original explicit instantiations provided in the library
+template class _LIBCPP_CLASS_TEMPLATE_INSTANTIATION_VIS basic_ios<char>;
+template class _LIBCPP_CLASS_TEMPLATE_INSTANTIATION_VIS basic_streambuf<char>;
+template class _LIBCPP_CLASS_TEMPLATE_INSTANTIATION_VIS basic_istream<char>;
+template class _LIBCPP_CLASS_TEMPLATE_INSTANTIATION_VIS basic_ostream<char>;
+template class _LIBCPP_CLASS_TEMPLATE_INSTANTIATION_VIS basic_iostream<char>;
+
+#ifndef _LIBCPP_HAS_NO_WIDE_CHARACTERS
+template class _LIBCPP_CLASS_TEMPLATE_INSTANTIATION_VIS basic_ios<wchar_t>;
+template class _LIBCPP_CLASS_TEMPLATE_INSTANTIATION_VIS basic_streambuf<wchar_t>;
+template class _LIBCPP_CLASS_TEMPLATE_INSTANTIATION_VIS basic_istream<wchar_t>;
+template class _LIBCPP_CLASS_TEMPLATE_INSTANTIATION_VIS basic_ostream<wchar_t>;
+#endif
+
+// Additional instantiations added later. Whether programs rely on these being
+// available is protected by _LIBCPP_ABI_ENABLE_ADDITIONAL_IOSTREAM_EXPLICIT_INSTANTIATIONS_1.
+template class _LIBCPP_CLASS_TEMPLATE_INSTANTIATION_VIS basic_stringbuf<char>;
+template class _LIBCPP_CLASS_TEMPLATE_INSTANTIATION_VIS basic_stringstream<char>;
+template class _LIBCPP_CLASS_TEMPLATE_INSTANTIATION_VIS basic_ostringstream<char>;
+template class _LIBCPP_CLASS_TEMPLATE_INSTANTIATION_VIS basic_istringstream<char>;
+
+#ifndef _LIBCPP_HAS_NO_FSTREAM
+template class _LIBCPP_CLASS_TEMPLATE_INSTANTIATION_VIS basic_ifstream<char>;
+template class _LIBCPP_CLASS_TEMPLATE_INSTANTIATION_VIS basic_ofstream<char>;
+template class _LIBCPP_CLASS_TEMPLATE_INSTANTIATION_VIS basic_filebuf<char>;
+#endif
+
+// Add more here if needed...
+
+_LIBCPP_END_NAMESPACE_STD

third_party/libcxx/src/iostream.cpp

@@ -0,0 +1,168 @@
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#include <__locale>
+#include "std_stream.h"
+#include <new>
+#include <string>
+
+#ifdef _LIBCPP_MSVCRT_LIKE
+#  include <__locale_dir/locale_base_api/locale_guard.h>
+#endif
+
+#define _str(s) #s
+#define str(s) _str(s)
+#define _LIBCPP_ABI_NAMESPACE_STR str(_LIBCPP_ABI_NAMESPACE)
+
+_LIBCPP_BEGIN_NAMESPACE_STD
+
+_ALIGNAS_TYPE (istream) _LIBCPP_FUNC_VIS char cin[sizeof(istream)]
+#if defined(_LIBCPP_ABI_MICROSOFT) && defined(__clang__)
+__asm__("?cin@" _LIBCPP_ABI_NAMESPACE_STR "@std@@3V?$basic_istream@DU?$char_traits@D@" _LIBCPP_ABI_NAMESPACE_STR "@std@@@12@A")
+#endif
+;
+_ALIGNAS_TYPE (__stdinbuf<char> ) static char __cin[sizeof(__stdinbuf <char>)];
+static mbstate_t mb_cin;
+
+#ifndef _LIBCPP_HAS_NO_WIDE_CHARACTERS
+_ALIGNAS_TYPE (wistream) _LIBCPP_FUNC_VIS char wcin[sizeof(wistream)]
+#if defined(_LIBCPP_ABI_MICROSOFT) && defined(__clang__)
+__asm__("?wcin@" _LIBCPP_ABI_NAMESPACE_STR "@std@@3V?$basic_istream@_WU?$char_traits@_W@" _LIBCPP_ABI_NAMESPACE_STR "@std@@@12@A")
+#endif
+;
+_ALIGNAS_TYPE (__stdinbuf<wchar_t> ) static char __wcin[sizeof(__stdinbuf <wchar_t>)];
+static mbstate_t mb_wcin;
+#endif // _LIBCPP_HAS_NO_WIDE_CHARACTERS
+
+_ALIGNAS_TYPE (ostream) _LIBCPP_FUNC_VIS char cout[sizeof(ostream)]
+#if defined(_LIBCPP_ABI_MICROSOFT) && defined(__clang__)
+__asm__("?cout@" _LIBCPP_ABI_NAMESPACE_STR "@std@@3V?$basic_ostream@DU?$char_traits@D@" _LIBCPP_ABI_NAMESPACE_STR "@std@@@12@A")
+#endif
+;
+_ALIGNAS_TYPE (__stdoutbuf<char>) static char __cout[sizeof(__stdoutbuf<char>)];
+static mbstate_t mb_cout;
+
+#ifndef _LIBCPP_HAS_NO_WIDE_CHARACTERS
+_ALIGNAS_TYPE (wostream) _LIBCPP_FUNC_VIS char wcout[sizeof(wostream)]
+#if defined(_LIBCPP_ABI_MICROSOFT) && defined(__clang__)
+__asm__("?wcout@" _LIBCPP_ABI_NAMESPACE_STR "@std@@3V?$basic_ostream@_WU?$char_traits@_W@" _LIBCPP_ABI_NAMESPACE_STR "@std@@@12@A")
+#endif
+;
+_ALIGNAS_TYPE (__stdoutbuf<wchar_t>) static char __wcout[sizeof(__stdoutbuf<wchar_t>)];
+static mbstate_t mb_wcout;
+#endif // _LIBCPP_HAS_NO_WIDE_CHARACTERS
+
+_ALIGNAS_TYPE (ostream) _LIBCPP_FUNC_VIS char cerr[sizeof(ostream)]
+#if defined(_LIBCPP_ABI_MICROSOFT) && defined(__clang__)
+__asm__("?cerr@" _LIBCPP_ABI_NAMESPACE_STR "@std@@3V?$basic_ostream@DU?$char_traits@D@" _LIBCPP_ABI_NAMESPACE_STR "@std@@@12@A")
+#endif
+;
+_ALIGNAS_TYPE (__stdoutbuf<char>) static char __cerr[sizeof(__stdoutbuf<char>)];
+static mbstate_t mb_cerr;
+
+#ifndef _LIBCPP_HAS_NO_WIDE_CHARACTERS
+_ALIGNAS_TYPE (wostream) _LIBCPP_FUNC_VIS char wcerr[sizeof(wostream)]
+#if defined(_LIBCPP_ABI_MICROSOFT) && defined(__clang__)
+__asm__("?wcerr@" _LIBCPP_ABI_NAMESPACE_STR "@std@@3V?$basic_ostream@_WU?$char_traits@_W@" _LIBCPP_ABI_NAMESPACE_STR "@std@@@12@A")
+#endif
+;
+_ALIGNAS_TYPE (__stdoutbuf<wchar_t>) static char __wcerr[sizeof(__stdoutbuf<wchar_t>)];
+static mbstate_t mb_wcerr;
+#endif // _LIBCPP_HAS_NO_WIDE_CHARACTERS
+
+_ALIGNAS_TYPE (ostream) _LIBCPP_FUNC_VIS char clog[sizeof(ostream)]
+#if defined(_LIBCPP_ABI_MICROSOFT) && defined(__clang__)
+__asm__("?clog@" _LIBCPP_ABI_NAMESPACE_STR "@std@@3V?$basic_ostream@DU?$char_traits@D@" _LIBCPP_ABI_NAMESPACE_STR "@std@@@12@A")
+#endif
+;
+
+#ifndef _LIBCPP_HAS_NO_WIDE_CHARACTERS
+_ALIGNAS_TYPE (wostream) _LIBCPP_FUNC_VIS char wclog[sizeof(wostream)]
+#if defined(_LIBCPP_ABI_MICROSOFT) && defined(__clang__)
+__asm__("?wclog@" _LIBCPP_ABI_NAMESPACE_STR "@std@@3V?$basic_ostream@_WU?$char_traits@_W@" _LIBCPP_ABI_NAMESPACE_STR "@std@@@12@A")
+#endif
+;
+#endif // _LIBCPP_HAS_NO_WIDE_CHARACTERS
+
+// Pretend we're inside a system header so the compiler doesn't flag the use of the init_priority
+// attribute with a value that's reserved for the implementation (we're the implementation).
+#include "iostream_init.h"
+
+// On Windows the TLS storage for locales needs to be initialized before we create
+// the standard streams, otherwise it may not be alive during program termination
+// when we flush the streams.
+static void force_locale_initialization() {
+#if defined(_LIBCPP_MSVCRT_LIKE)
+  static bool once = []() {
+    auto loc = newlocale(LC_ALL_MASK, "C", 0);
+    {
+        __libcpp_locale_guard g(loc); // forces initialization of locale TLS
+        ((void)g);
+    }
+    freelocale(loc);
+    return true;
+  }();
+  ((void)once);
+#endif
+}
+
+class DoIOSInit {
+public:
+    DoIOSInit();
+    ~DoIOSInit();
+};
+
+DoIOSInit::DoIOSInit()
+{
+    force_locale_initialization();
+
+    istream* cin_ptr  = ::new(cin)  istream(::new(__cin)  __stdinbuf <char>(stdin, &mb_cin));
+    ostream* cout_ptr = ::new(cout) ostream(::new(__cout) __stdoutbuf<char>(stdout, &mb_cout));
+    ostream* cerr_ptr = ::new(cerr) ostream(::new(__cerr) __stdoutbuf<char>(stderr, &mb_cerr));
+                        ::new(clog) ostream(cerr_ptr->rdbuf());
+    cin_ptr->tie(cout_ptr);
+    _VSTD::unitbuf(*cerr_ptr);
+    cerr_ptr->tie(cout_ptr);
+
+#ifndef _LIBCPP_HAS_NO_WIDE_CHARACTERS
+    wistream* wcin_ptr  = ::new(wcin)  wistream(::new(__wcin)  __stdinbuf <wchar_t>(stdin, &mb_wcin));
+    wostream* wcout_ptr = ::new(wcout) wostream(::new(__wcout) __stdoutbuf<wchar_t>(stdout, &mb_wcout));
+    wostream* wcerr_ptr = ::new(wcerr) wostream(::new(__wcerr) __stdoutbuf<wchar_t>(stderr, &mb_wcerr));
+                          ::new(wclog) wostream(wcerr_ptr->rdbuf());
+
+    wcin_ptr->tie(wcout_ptr);
+    _VSTD::unitbuf(*wcerr_ptr);
+    wcerr_ptr->tie(wcout_ptr);
+#endif
+}
+
+DoIOSInit::~DoIOSInit()
+{
+    ostream* cout_ptr = reinterpret_cast<ostream*>(cout);
+    cout_ptr->flush();
+    ostream* clog_ptr = reinterpret_cast<ostream*>(clog);
+    clog_ptr->flush();
+
+#ifndef _LIBCPP_HAS_NO_WIDE_CHARACTERS
+    wostream* wcout_ptr = reinterpret_cast<wostream*>(wcout);
+    wcout_ptr->flush();
+    wostream* wclog_ptr = reinterpret_cast<wostream*>(wclog);
+    wclog_ptr->flush();
+#endif
+}
+
+ios_base::Init::Init()
+{
+    static DoIOSInit init_the_streams; // gets initialized once
+}
+
+ios_base::Init::~Init()
+{
+}
+
+_LIBCPP_END_NAMESPACE_STD

third_party/libcxx/src/iostream_init.h

@@ -0,0 +1,2 @@
+#pragma GCC system_header
+_LIBCPP_HIDDEN ios_base::Init __start_std_streams _LIBCPP_INIT_PRIORITY_MAX;

third_party/libcxx/src/legacy_debug_handler.cpp

@@ -0,0 +1,54 @@
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#include <__config>
+#include <cstdio>
+#include <cstdlib>
+#include <string>
+
+// This file defines the legacy default debug handler and related mechanisms
+// to set it. This is for backwards ABI compatibility with code that has been
+// using this debug handler previously.
+
+_LIBCPP_BEGIN_NAMESPACE_STD
+
+struct _LIBCPP_TEMPLATE_VIS __libcpp_debug_info {
+  _LIBCPP_EXPORTED_FROM_ABI string what() const;
+
+  const char* __file_;
+  int __line_;
+  const char* __pred_;
+  const char* __msg_;
+};
+
+std::string __libcpp_debug_info::what() const {
+  string msg = __file_;
+  msg += ":" + std::to_string(__line_) + ": _LIBCPP_ASSERT '";
+  msg += __pred_;
+  msg += "' failed. ";
+  msg += __msg_;
+  return msg;
+}
+
+_LIBCPP_NORETURN _LIBCPP_EXPORTED_FROM_ABI void __libcpp_abort_debug_function(__libcpp_debug_info const& info) {
+  std::fprintf(stderr, "%s\n", info.what().c_str());
+  std::abort();
+}
+
+typedef void (*__libcpp_debug_function_type)(__libcpp_debug_info const&);
+
+_LIBCPP_EXPORTED_FROM_ABI
+constinit __libcpp_debug_function_type __libcpp_debug_function = __libcpp_abort_debug_function;
+
+_LIBCPP_EXPORTED_FROM_ABI
+bool __libcpp_set_debug_function(__libcpp_debug_function_type __func) {
+  __libcpp_debug_function = __func;
+  return true;
+}
+
+_LIBCPP_END_NAMESPACE_STD

third_party/libcxx/src/legacy_pointer_safety.cpp

@@ -0,0 +1,23 @@
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#include <__config>
+#include <memory>
+
+// Support for garbage collection was removed in C++23 by https://wg21.link/P2186R2. Libc++ implements
+// that removal as an extension in all Standard versions. However, we still define the functions that
+// were once part of the library's ABI for backwards compatibility.
+
+_LIBCPP_BEGIN_NAMESPACE_STD
+
+_LIBCPP_FUNC_VIS void declare_reachable(void*) {}
+_LIBCPP_FUNC_VIS void declare_no_pointers(char*, size_t) {}
+_LIBCPP_FUNC_VIS void undeclare_no_pointers(char*, size_t) {}
+_LIBCPP_FUNC_VIS void* __undeclare_reachable(void* p) { return p; }
+
+_LIBCPP_END_NAMESPACE_STD

third_party/libcxx/src/memory.cpp

@@ -0,0 +1,207 @@
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#include <__config>
+#ifdef _LIBCPP_DEPRECATED_ABI_LEGACY_LIBRARY_DEFINITIONS_FOR_INLINE_FUNCTIONS
+#   define _LIBCPP_SHARED_PTR_DEFINE_LEGACY_INLINE_FUNCTIONS
+#endif
+
+#include <memory>
+
+#ifndef _LIBCPP_HAS_NO_THREADS
+#  include <mutex>
+#  include <thread>
+#  if defined(__ELF__) && defined(_LIBCPP_LINK_PTHREAD_LIB)
+#    pragma comment(lib, "pthread")
+#  endif
+#endif
+
+#include "third_party/libcxx/src/include/atomic_support.h"
+
+_LIBCPP_BEGIN_NAMESPACE_STD
+
+bad_weak_ptr::~bad_weak_ptr() noexcept {}
+
+const char*
+bad_weak_ptr::what() const noexcept
+{
+    return "bad_weak_ptr";
+}
+
+__shared_count::~__shared_count()
+{
+}
+
+__shared_weak_count::~__shared_weak_count()
+{
+}
+
+#if defined(_LIBCPP_SHARED_PTR_DEFINE_LEGACY_INLINE_FUNCTIONS)
+void
+__shared_count::__add_shared() noexcept
+{
+    __libcpp_atomic_refcount_increment(__shared_owners_);
+}
+
+bool
+__shared_count::__release_shared() noexcept
+{
+    if (__libcpp_atomic_refcount_decrement(__shared_owners_) == -1)
+    {
+        __on_zero_shared();
+        return true;
+    }
+    return false;
+}
+
+void
+__shared_weak_count::__add_shared() noexcept
+{
+    __shared_count::__add_shared();
+}
+
+void
+__shared_weak_count::__add_weak() noexcept
+{
+    __libcpp_atomic_refcount_increment(__shared_weak_owners_);
+}
+
+void
+__shared_weak_count::__release_shared() noexcept
+{
+    if (__shared_count::__release_shared())
+        __release_weak();
+}
+#endif // _LIBCPP_SHARED_PTR_DEFINE_LEGACY_INLINE_FUNCTIONS
+
+void
+__shared_weak_count::__release_weak() noexcept
+{
+    // NOTE: The acquire load here is an optimization of the very
+    // common case where a shared pointer is being destructed while
+    // having no other contended references.
+    //
+    // BENEFIT: We avoid expensive atomic stores like XADD and STREX
+    // in a common case.  Those instructions are slow and do nasty
+    // things to caches.
+    //
+    // IS THIS SAFE?  Yes.  During weak destruction, if we see that we
+    // are the last reference, we know that no-one else is accessing
+    // us. If someone were accessing us, then they would be doing so
+    // while the last shared / weak_ptr was being destructed, and
+    // that's undefined anyway.
+    //
+    // If we see anything other than a 0, then we have possible
+    // contention, and need to use an atomicrmw primitive.
+    // The same arguments don't apply for increment, where it is legal
+    // (though inadvisable) to share shared_ptr references between
+    // threads, and have them all get copied at once.  The argument
+    // also doesn't apply for __release_shared, because an outstanding
+    // weak_ptr::lock() could read / modify the shared count.
+    if (__libcpp_atomic_load(&__shared_weak_owners_, _AO_Acquire) == 0)
+    {
+        // no need to do this store, because we are about
+        // to destroy everything.
+        //__libcpp_atomic_store(&__shared_weak_owners_, -1, _AO_Release);
+        __on_zero_shared_weak();
+    }
+    else if (__libcpp_atomic_refcount_decrement(__shared_weak_owners_) == -1)
+        __on_zero_shared_weak();
+}
+
+__shared_weak_count*
+__shared_weak_count::lock() noexcept
+{
+    long object_owners = __libcpp_atomic_load(&__shared_owners_);
+    while (object_owners != -1)
+    {
+        if (__libcpp_atomic_compare_exchange(&__shared_owners_,
+                                             &object_owners,
+                                             object_owners+1))
+            return this;
+    }
+    return nullptr;
+}
+
+const void*
+__shared_weak_count::__get_deleter(const type_info&) const noexcept
+{
+    return nullptr;
+}
+
+#if !defined(_LIBCPP_HAS_NO_THREADS)
+
+static constexpr std::size_t __sp_mut_count = 32;
+static constinit __libcpp_mutex_t mut_back[__sp_mut_count] =
+{
+    _LIBCPP_MUTEX_INITIALIZER, _LIBCPP_MUTEX_INITIALIZER, _LIBCPP_MUTEX_INITIALIZER, _LIBCPP_MUTEX_INITIALIZER,
+    _LIBCPP_MUTEX_INITIALIZER, _LIBCPP_MUTEX_INITIALIZER, _LIBCPP_MUTEX_INITIALIZER, _LIBCPP_MUTEX_INITIALIZER,
+    _LIBCPP_MUTEX_INITIALIZER, _LIBCPP_MUTEX_INITIALIZER, _LIBCPP_MUTEX_INITIALIZER, _LIBCPP_MUTEX_INITIALIZER,
+    _LIBCPP_MUTEX_INITIALIZER, _LIBCPP_MUTEX_INITIALIZER, _LIBCPP_MUTEX_INITIALIZER, _LIBCPP_MUTEX_INITIALIZER,
+    _LIBCPP_MUTEX_INITIALIZER, _LIBCPP_MUTEX_INITIALIZER, _LIBCPP_MUTEX_INITIALIZER, _LIBCPP_MUTEX_INITIALIZER,
+    _LIBCPP_MUTEX_INITIALIZER, _LIBCPP_MUTEX_INITIALIZER, _LIBCPP_MUTEX_INITIALIZER, _LIBCPP_MUTEX_INITIALIZER,
+    _LIBCPP_MUTEX_INITIALIZER, _LIBCPP_MUTEX_INITIALIZER, _LIBCPP_MUTEX_INITIALIZER, _LIBCPP_MUTEX_INITIALIZER,
+    _LIBCPP_MUTEX_INITIALIZER, _LIBCPP_MUTEX_INITIALIZER, _LIBCPP_MUTEX_INITIALIZER, _LIBCPP_MUTEX_INITIALIZER
+};
+
+_LIBCPP_CONSTEXPR __sp_mut::__sp_mut(void* p) noexcept
+   : __lx_(p)
+{
+}
+
+void
+__sp_mut::lock() noexcept
+{
+    auto m = static_cast<__libcpp_mutex_t*>(__lx_);
+    __libcpp_mutex_lock(m);
+}
+
+void
+__sp_mut::unlock() noexcept
+{
+    __libcpp_mutex_unlock(static_cast<__libcpp_mutex_t*>(__lx_));
+}
+
+__sp_mut&
+__get_sp_mut(const void* p)
+{
+    static constinit __sp_mut muts[__sp_mut_count] = {
+        &mut_back[ 0], &mut_back[ 1], &mut_back[ 2], &mut_back[ 3],
+        &mut_back[ 4], &mut_back[ 5], &mut_back[ 6], &mut_back[ 7],
+        &mut_back[ 8], &mut_back[ 9], &mut_back[10], &mut_back[11],
+        &mut_back[12], &mut_back[13], &mut_back[14], &mut_back[15],
+        &mut_back[16], &mut_back[17], &mut_back[18], &mut_back[19],
+        &mut_back[20], &mut_back[21], &mut_back[22], &mut_back[23],
+        &mut_back[24], &mut_back[25], &mut_back[26], &mut_back[27],
+        &mut_back[28], &mut_back[29], &mut_back[30], &mut_back[31]
+    };
+    return muts[hash<const void*>()(p) & (__sp_mut_count-1)];
+}
+
+#endif // !defined(_LIBCPP_HAS_NO_THREADS)
+
+void*
+align(size_t alignment, size_t size, void*& ptr, size_t& space)
+{
+    void* r = nullptr;
+    if (size <= space)
+    {
+        char* p1 = static_cast<char*>(ptr);
+        char* p2 = reinterpret_cast<char*>(reinterpret_cast<uintptr_t>(p1 + (alignment - 1)) & -alignment);
+        size_t d = static_cast<size_t>(p2 - p1);
+        if (d <= space - size)
+        {
+            r = p2;
+            ptr = r;
+            space -= d;
+        }
+    }
+    return r;
+}
+
+_LIBCPP_END_NAMESPACE_STD

third_party/libcxx/src/memory_resource.cpp

@@ -0,0 +1,496 @@
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#include <memory>
+#include <memory_resource>
+
+#ifndef _LIBCPP_HAS_NO_ATOMIC_HEADER
+#  include <atomic>
+#elif !defined(_LIBCPP_HAS_NO_THREADS)
+#  include <mutex>
+#  if defined(__ELF__) && defined(_LIBCPP_LINK_PTHREAD_LIB)
+#    pragma comment(lib, "pthread")
+#  endif
+#endif
+
+_LIBCPP_BEGIN_NAMESPACE_STD
+
+namespace pmr {
+
+// memory_resource
+
+memory_resource::~memory_resource() = default;
+
+// new_delete_resource()
+
+#ifdef _LIBCPP_HAS_NO_ALIGNED_ALLOCATION
+static bool is_aligned_to(void* ptr, size_t align) {
+  void* p2     = ptr;
+  size_t space = 1;
+  void* result = std::align(align, 1, p2, space);
+  return (result == ptr);
+}
+#endif
+
+class _LIBCPP_TYPE_VIS __new_delete_memory_resource_imp : public memory_resource {
+  void* do_allocate(size_t bytes, size_t align) override {
+#ifndef _LIBCPP_HAS_NO_ALIGNED_ALLOCATION
+    return std::__libcpp_allocate(bytes, align);
+#else
+    if (bytes == 0)
+      bytes = 1;
+    void* result = std::__libcpp_allocate(bytes, align);
+    if (!is_aligned_to(result, align)) {
+      std::__libcpp_deallocate(result, bytes, align);
+      __throw_bad_alloc();
+    }
+    return result;
+#endif
+  }
+
+  void do_deallocate(void* p, size_t bytes, size_t align) override { std::__libcpp_deallocate(p, bytes, align); }
+
+  bool do_is_equal(const memory_resource& other) const noexcept override { return &other == this; }
+};
+
+// null_memory_resource()
+
+class _LIBCPP_TYPE_VIS __null_memory_resource_imp : public memory_resource {
+  void* do_allocate(size_t, size_t) override { __throw_bad_alloc(); }
+  void do_deallocate(void*, size_t, size_t) override {}
+  bool do_is_equal(const memory_resource& other) const noexcept override { return &other == this; }
+};
+
+namespace {
+
+union ResourceInitHelper {
+  struct {
+    __new_delete_memory_resource_imp new_delete_res;
+    __null_memory_resource_imp null_res;
+  } resources;
+  char dummy;
+  _LIBCPP_CONSTEXPR_SINCE_CXX14 ResourceInitHelper() : resources() {}
+  ~ResourceInitHelper() {}
+};
+
+// Pretend we're inside a system header so the compiler doesn't flag the use of the init_priority
+// attribute with a value that's reserved for the implementation (we're the implementation).
+#include "memory_resource_init_helper.h"
+
+} // end namespace
+
+memory_resource* new_delete_resource() noexcept { return &res_init.resources.new_delete_res; }
+
+memory_resource* null_memory_resource() noexcept { return &res_init.resources.null_res; }
+
+// default_memory_resource()
+
+static memory_resource* __default_memory_resource(bool set = false, memory_resource* new_res = nullptr) noexcept {
+#ifndef _LIBCPP_HAS_NO_ATOMIC_HEADER
+  static constinit atomic<memory_resource*> __res{&res_init.resources.new_delete_res};
+  if (set) {
+    new_res = new_res ? new_res : new_delete_resource();
+    // TODO: Can a weaker ordering be used?
+    return std::atomic_exchange_explicit(&__res, new_res, memory_order_acq_rel);
+  } else {
+    return std::atomic_load_explicit(&__res, memory_order_acquire);
+  }
+#elif !defined(_LIBCPP_HAS_NO_THREADS)
+  static constinit memory_resource* res = &res_init.resources.new_delete_res;
+  static mutex res_lock;
+  if (set) {
+    new_res = new_res ? new_res : new_delete_resource();
+    lock_guard<mutex> guard(res_lock);
+    memory_resource* old_res = res;
+    res                      = new_res;
+    return old_res;
+  } else {
+    lock_guard<mutex> guard(res_lock);
+    return res;
+  }
+#else
+  static constinit memory_resource* res = &res_init.resources.new_delete_res;
+  if (set) {
+    new_res                  = new_res ? new_res : new_delete_resource();
+    memory_resource* old_res = res;
+    res                      = new_res;
+    return old_res;
+  } else {
+    return res;
+  }
+#endif
+}
+
+memory_resource* get_default_resource() noexcept { return __default_memory_resource(); }
+
+memory_resource* set_default_resource(memory_resource* __new_res) noexcept {
+  return __default_memory_resource(true, __new_res);
+}
+
+// 23.12.5, mem.res.pool
+
+static size_t roundup(size_t count, size_t alignment) {
+  size_t mask = alignment - 1;
+  return (count + mask) & ~mask;
+}
+
+struct unsynchronized_pool_resource::__adhoc_pool::__chunk_footer {
+  __chunk_footer* __next_;
+  char* __start_;
+  size_t __align_;
+  size_t __allocation_size() { return (reinterpret_cast<char*>(this) - __start_) + sizeof(*this); }
+};
+
+void unsynchronized_pool_resource::__adhoc_pool::__release_ptr(memory_resource* upstream) {
+  while (__first_ != nullptr) {
+    __chunk_footer* next = __first_->__next_;
+    upstream->deallocate(__first_->__start_, __first_->__allocation_size(), __first_->__align_);
+    __first_ = next;
+  }
+}
+
+void* unsynchronized_pool_resource::__adhoc_pool::__do_allocate(memory_resource* upstream, size_t bytes, size_t align) {
+  const size_t footer_size  = sizeof(__chunk_footer);
+  const size_t footer_align = alignof(__chunk_footer);
+
+  if (align < footer_align)
+    align = footer_align;
+
+  size_t aligned_capacity = roundup(bytes, footer_align) + footer_size;
+
+  void* result = upstream->allocate(aligned_capacity, align);
+
+  __chunk_footer* h = (__chunk_footer*)((char*)result + aligned_capacity - footer_size);
+  h->__next_        = __first_;
+  h->__start_       = (char*)result;
+  h->__align_       = align;
+  __first_          = h;
+  return result;
+}
+
+void unsynchronized_pool_resource::__adhoc_pool::__do_deallocate(
+    memory_resource* upstream, void* p, size_t bytes, size_t align) {
+  _LIBCPP_ASSERT(__first_ != nullptr, "deallocating a block that was not allocated with this allocator");
+  if (__first_->__start_ == p) {
+    __chunk_footer* next = __first_->__next_;
+    upstream->deallocate(p, __first_->__allocation_size(), __first_->__align_);
+    __first_ = next;
+  } else {
+    for (__chunk_footer* h = __first_; h->__next_ != nullptr; h = h->__next_) {
+      if (h->__next_->__start_ == p) {
+        __chunk_footer* next = h->__next_->__next_;
+        upstream->deallocate(p, h->__next_->__allocation_size(), h->__next_->__align_);
+        h->__next_ = next;
+        return;
+      }
+    }
+    _LIBCPP_ASSERT(false, "deallocating a block that was not allocated with this allocator");
+  }
+}
+
+class unsynchronized_pool_resource::__fixed_pool {
+  struct __chunk_footer {
+    __chunk_footer* __next_;
+    char* __start_;
+    size_t __align_;
+    size_t __allocation_size() { return (reinterpret_cast<char*>(this) - __start_) + sizeof(*this); }
+  };
+
+  struct __vacancy_header {
+    __vacancy_header* __next_vacancy_;
+  };
+
+  __chunk_footer* __first_chunk_     = nullptr;
+  __vacancy_header* __first_vacancy_ = nullptr;
+
+public:
+  explicit __fixed_pool() = default;
+
+  void __release_ptr(memory_resource* upstream) {
+    __first_vacancy_ = nullptr;
+    while (__first_chunk_ != nullptr) {
+      __chunk_footer* next = __first_chunk_->__next_;
+      upstream->deallocate(__first_chunk_->__start_, __first_chunk_->__allocation_size(), __first_chunk_->__align_);
+      __first_chunk_ = next;
+    }
+  }
+
+  void* __try_allocate_from_vacancies() {
+    if (__first_vacancy_ != nullptr) {
+      void* result     = __first_vacancy_;
+      __first_vacancy_ = __first_vacancy_->__next_vacancy_;
+      return result;
+    }
+    return nullptr;
+  }
+
+  void* __allocate_in_new_chunk(memory_resource* upstream, size_t block_size, size_t chunk_size) {
+    _LIBCPP_ASSERT(chunk_size % block_size == 0, "");
+    static_assert(__default_alignment >= alignof(std::max_align_t), "");
+    static_assert(__default_alignment >= alignof(__chunk_footer), "");
+    static_assert(__default_alignment >= alignof(__vacancy_header), "");
+
+    const size_t footer_size  = sizeof(__chunk_footer);
+    const size_t footer_align = alignof(__chunk_footer);
+
+    size_t aligned_capacity = roundup(chunk_size, footer_align) + footer_size;
+
+    void* result = upstream->allocate(aligned_capacity, __default_alignment);
+
+    __chunk_footer* h = (__chunk_footer*)((char*)result + aligned_capacity - footer_size);
+    h->__next_        = __first_chunk_;
+    h->__start_       = (char*)result;
+    h->__align_       = __default_alignment;
+    __first_chunk_    = h;
+
+    if (chunk_size > block_size) {
+      __vacancy_header* last_vh = this->__first_vacancy_;
+      for (size_t i = block_size; i != chunk_size; i += block_size) {
+        __vacancy_header* vh = (__vacancy_header*)((char*)result + i);
+        vh->__next_vacancy_  = last_vh;
+        last_vh              = vh;
+      }
+      this->__first_vacancy_ = last_vh;
+    }
+    return result;
+  }
+
+  void __evacuate(void* p) {
+    __vacancy_header* vh = (__vacancy_header*)(p);
+    vh->__next_vacancy_  = __first_vacancy_;
+    __first_vacancy_     = vh;
+  }
+
+  size_t __previous_chunk_size_in_bytes() const { return __first_chunk_ ? __first_chunk_->__allocation_size() : 0; }
+
+  static const size_t __default_alignment = alignof(max_align_t);
+};
+
+size_t unsynchronized_pool_resource::__pool_block_size(int i) const { return size_t(1) << __log2_pool_block_size(i); }
+
+int unsynchronized_pool_resource::__log2_pool_block_size(int i) const { return (i + __log2_smallest_block_size); }
+
+int unsynchronized_pool_resource::__pool_index(size_t bytes, size_t align) const {
+  if (align > alignof(std::max_align_t) || bytes > (size_t(1) << __num_fixed_pools_))
+    return __num_fixed_pools_;
+  else {
+    int i = 0;
+    bytes = (bytes > align) ? bytes : align;
+    bytes -= 1;
+    bytes >>= __log2_smallest_block_size;
+    while (bytes != 0) {
+      bytes >>= 1;
+      i += 1;
+    }
+    return i;
+  }
+}
+
+unsynchronized_pool_resource::unsynchronized_pool_resource(const pool_options& opts, memory_resource* upstream)
+    : __res_(upstream), __fixed_pools_(nullptr) {
+  size_t largest_block_size;
+  if (opts.largest_required_pool_block == 0)
+    largest_block_size = __default_largest_block_size;
+  else if (opts.largest_required_pool_block < __smallest_block_size)
+    largest_block_size = __smallest_block_size;
+  else if (opts.largest_required_pool_block > __max_largest_block_size)
+    largest_block_size = __max_largest_block_size;
+  else
+    largest_block_size = opts.largest_required_pool_block;
+
+  if (opts.max_blocks_per_chunk == 0)
+    __options_max_blocks_per_chunk_ = __max_blocks_per_chunk;
+  else if (opts.max_blocks_per_chunk < __min_blocks_per_chunk)
+    __options_max_blocks_per_chunk_ = __min_blocks_per_chunk;
+  else if (opts.max_blocks_per_chunk > __max_blocks_per_chunk)
+    __options_max_blocks_per_chunk_ = __max_blocks_per_chunk;
+  else
+    __options_max_blocks_per_chunk_ = opts.max_blocks_per_chunk;
+
+  __num_fixed_pools_ = 1;
+  size_t capacity    = __smallest_block_size;
+  while (capacity < largest_block_size) {
+    capacity <<= 1;
+    __num_fixed_pools_ += 1;
+  }
+}
+
+pool_options unsynchronized_pool_resource::options() const {
+  pool_options p;
+  p.max_blocks_per_chunk        = __options_max_blocks_per_chunk_;
+  p.largest_required_pool_block = __pool_block_size(__num_fixed_pools_ - 1);
+  return p;
+}
+
+void unsynchronized_pool_resource::release() {
+  __adhoc_pool_.__release_ptr(__res_);
+  if (__fixed_pools_ != nullptr) {
+    const int n = __num_fixed_pools_;
+    for (int i = 0; i < n; ++i)
+      __fixed_pools_[i].__release_ptr(__res_);
+    __res_->deallocate(__fixed_pools_, __num_fixed_pools_ * sizeof(__fixed_pool), alignof(__fixed_pool));
+    __fixed_pools_ = nullptr;
+  }
+}
+
+void* unsynchronized_pool_resource::do_allocate(size_t bytes, size_t align) {
+  // A pointer to allocated storage (6.6.4.4.1) with a size of at least bytes.
+  // The size and alignment of the allocated memory shall meet the requirements for
+  // a class derived from memory_resource (23.12).
+  // If the pool selected for a block of size bytes is unable to satisfy the memory request
+  // from its own internal data structures, it will call upstream_resource()->allocate()
+  // to obtain more memory. If bytes is larger than that which the largest pool can handle,
+  // then memory will be allocated using upstream_resource()->allocate().
+
+  int i = __pool_index(bytes, align);
+  if (i == __num_fixed_pools_)
+    return __adhoc_pool_.__do_allocate(__res_, bytes, align);
+  else {
+    if (__fixed_pools_ == nullptr) {
+      __fixed_pools_ =
+          (__fixed_pool*)__res_->allocate(__num_fixed_pools_ * sizeof(__fixed_pool), alignof(__fixed_pool));
+      __fixed_pool* first = __fixed_pools_;
+      __fixed_pool* last  = __fixed_pools_ + __num_fixed_pools_;
+      for (__fixed_pool* pool = first; pool != last; ++pool)
+        ::new ((void*)pool) __fixed_pool;
+    }
+    void* result = __fixed_pools_[i].__try_allocate_from_vacancies();
+    if (result == nullptr) {
+      auto min = [](size_t a, size_t b) { return a < b ? a : b; };
+      auto max = [](size_t a, size_t b) { return a < b ? b : a; };
+
+      size_t prev_chunk_size_in_bytes  = __fixed_pools_[i].__previous_chunk_size_in_bytes();
+      size_t prev_chunk_size_in_blocks = prev_chunk_size_in_bytes >> __log2_pool_block_size(i);
+
+      size_t chunk_size_in_blocks;
+
+      if (prev_chunk_size_in_blocks == 0) {
+        size_t min_blocks_per_chunk = max(__min_bytes_per_chunk >> __log2_pool_block_size(i), __min_blocks_per_chunk);
+        chunk_size_in_blocks        = min_blocks_per_chunk;
+      } else {
+        static_assert(__max_bytes_per_chunk <= SIZE_MAX - (__max_bytes_per_chunk / 4), "unsigned overflow is possible");
+        chunk_size_in_blocks = prev_chunk_size_in_blocks + (prev_chunk_size_in_blocks / 4);
+      }
+
+      size_t max_blocks_per_chunk =
+          min((__max_bytes_per_chunk >> __log2_pool_block_size(i)),
+              min(__max_blocks_per_chunk, __options_max_blocks_per_chunk_));
+      if (chunk_size_in_blocks > max_blocks_per_chunk)
+        chunk_size_in_blocks = max_blocks_per_chunk;
+
+      size_t block_size = __pool_block_size(i);
+
+      size_t chunk_size_in_bytes = (chunk_size_in_blocks << __log2_pool_block_size(i));
+      result                     = __fixed_pools_[i].__allocate_in_new_chunk(__res_, block_size, chunk_size_in_bytes);
+    }
+    return result;
+  }
+}
+
+void unsynchronized_pool_resource::do_deallocate(void* p, size_t bytes, size_t align) {
+  // Returns the memory at p to the pool. It is unspecified if,
+  // or under what circumstances, this operation will result in
+  // a call to upstream_resource()->deallocate().
+
+  int i = __pool_index(bytes, align);
+  if (i == __num_fixed_pools_)
+    return __adhoc_pool_.__do_deallocate(__res_, p, bytes, align);
+  else {
+    _LIBCPP_ASSERT(__fixed_pools_ != nullptr, "deallocating a block that was not allocated with this allocator");
+    __fixed_pools_[i].__evacuate(p);
+  }
+}
+
+bool synchronized_pool_resource::do_is_equal(const memory_resource& other) const noexcept { return &other == this; }
+
+// 23.12.6, mem.res.monotonic.buffer
+
+static void* align_down(size_t align, size_t size, void*& ptr, size_t& space) {
+  if (size > space)
+    return nullptr;
+
+  char* p1      = static_cast<char*>(ptr);
+  char* new_ptr = reinterpret_cast<char*>(reinterpret_cast<uintptr_t>(p1 - size) & ~(align - 1));
+
+  if (new_ptr < (p1 - space))
+    return nullptr;
+
+  ptr = new_ptr;
+  space -= p1 - new_ptr;
+
+  return ptr;
+}
+
+void* monotonic_buffer_resource::__initial_descriptor::__try_allocate_from_chunk(size_t bytes, size_t align) {
+  if (!__cur_)
+    return nullptr;
+  void* new_ptr       = static_cast<void*>(__cur_);
+  size_t new_capacity = (__cur_ - __start_);
+  void* aligned_ptr   = align_down(align, bytes, new_ptr, new_capacity);
+  if (aligned_ptr != nullptr)
+    __cur_ = static_cast<char*>(new_ptr);
+  return aligned_ptr;
+}
+
+void* monotonic_buffer_resource::__chunk_footer::__try_allocate_from_chunk(size_t bytes, size_t align) {
+  void* new_ptr       = static_cast<void*>(__cur_);
+  size_t new_capacity = (__cur_ - __start_);
+  void* aligned_ptr   = align_down(align, bytes, new_ptr, new_capacity);
+  if (aligned_ptr != nullptr)
+    __cur_ = static_cast<char*>(new_ptr);
+  return aligned_ptr;
+}
+
+void* monotonic_buffer_resource::do_allocate(size_t bytes, size_t align) {
+  const size_t footer_size  = sizeof(__chunk_footer);
+  const size_t footer_align = alignof(__chunk_footer);
+
+  auto previous_allocation_size = [&]() {
+    if (__chunks_ != nullptr)
+      return __chunks_->__allocation_size();
+
+    size_t newsize = (__initial_.__start_ != nullptr) ? (__initial_.__end_ - __initial_.__start_) : __initial_.__size_;
+
+    return roundup(newsize, footer_align) + footer_size;
+  };
+
+  if (void* result = __initial_.__try_allocate_from_chunk(bytes, align))
+    return result;
+  if (__chunks_ != nullptr) {
+    if (void* result = __chunks_->__try_allocate_from_chunk(bytes, align))
+      return result;
+  }
+
+  // Allocate a brand-new chunk.
+
+  if (align < footer_align)
+    align = footer_align;
+
+  size_t aligned_capacity  = roundup(bytes, footer_align) + footer_size;
+  size_t previous_capacity = previous_allocation_size();
+
+  if (aligned_capacity <= previous_capacity) {
+    size_t newsize   = 2 * (previous_capacity - footer_size);
+    aligned_capacity = roundup(newsize, footer_align) + footer_size;
+  }
+
+  char* start            = (char*)__res_->allocate(aligned_capacity, align);
+  auto end               = start + aligned_capacity - footer_size;
+  __chunk_footer* footer = (__chunk_footer*)(end);
+  footer->__next_        = __chunks_;
+  footer->__start_       = start;
+  footer->__cur_         = end;
+  footer->__align_       = align;
+  __chunks_              = footer;
+
+  return __chunks_->__try_allocate_from_chunk(bytes, align);
+}
+
+} // namespace pmr
+
+_LIBCPP_END_NAMESPACE_STD

third_party/libcxx/src/memory_resource_init_helper.h

@@ -0,0 +1,2 @@
+#pragma GCC system_header
+static constinit ResourceInitHelper res_init _LIBCPP_INIT_PRIORITY_MAX;

third_party/libcxx/src/mutex.cpp

@@ -0,0 +1,262 @@
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#include <__assert>
+#include <limits>
+#include <mutex>
+
+#include "third_party/libcxx/src/include/atomic_support.h"
+
+#ifndef _LIBCPP_HAS_NO_THREADS
+#  if defined(__ELF__) && defined(_LIBCPP_LINK_PTHREAD_LIB)
+#    pragma comment(lib, "pthread")
+#  endif
+#endif
+
+_LIBCPP_PUSH_MACROS
+#include <__undef_macros>
+
+_LIBCPP_BEGIN_NAMESPACE_STD
+
+#ifndef _LIBCPP_HAS_NO_THREADS
+
+// ~mutex is defined elsewhere
+
+void
+mutex::lock()
+{
+    int ec = __libcpp_mutex_lock(&__m_);
+    if (ec)
+        __throw_system_error(ec, "mutex lock failed");
+}
+
+bool
+mutex::try_lock() noexcept
+{
+    return __libcpp_mutex_trylock(&__m_);
+}
+
+void
+mutex::unlock() noexcept
+{
+    int ec = __libcpp_mutex_unlock(&__m_);
+    (void)ec;
+    _LIBCPP_ASSERT(ec == 0, "call to mutex::unlock failed");
+}
+
+// recursive_mutex
+
+recursive_mutex::recursive_mutex()
+{
+    int ec = __libcpp_recursive_mutex_init(&__m_);
+    if (ec)
+        __throw_system_error(ec, "recursive_mutex constructor failed");
+}
+
+recursive_mutex::~recursive_mutex()
+{
+    int e = __libcpp_recursive_mutex_destroy(&__m_);
+    (void)e;
+    _LIBCPP_ASSERT(e == 0, "call to ~recursive_mutex() failed");
+}
+
+void
+recursive_mutex::lock()
+{
+    int ec = __libcpp_recursive_mutex_lock(&__m_);
+    if (ec)
+        __throw_system_error(ec, "recursive_mutex lock failed");
+}
+
+void
+recursive_mutex::unlock() noexcept
+{
+    int e = __libcpp_recursive_mutex_unlock(&__m_);
+    (void)e;
+    _LIBCPP_ASSERT(e == 0, "call to recursive_mutex::unlock() failed");
+}
+
+bool
+recursive_mutex::try_lock() noexcept
+{
+    return __libcpp_recursive_mutex_trylock(&__m_);
+}
+
+// timed_mutex
+
+timed_mutex::timed_mutex()
+    : __locked_(false)
+{
+}
+
+timed_mutex::~timed_mutex()
+{
+    lock_guard<mutex> _(__m_);
+}
+
+void
+timed_mutex::lock()
+{
+    unique_lock<mutex> lk(__m_);
+    while (__locked_)
+        __cv_.wait(lk);
+    __locked_ = true;
+}
+
+bool
+timed_mutex::try_lock() noexcept
+{
+    unique_lock<mutex> lk(__m_, try_to_lock);
+    if (lk.owns_lock() && !__locked_)
+    {
+        __locked_ = true;
+        return true;
+    }
+    return false;
+}
+
+void
+timed_mutex::unlock() noexcept
+{
+    lock_guard<mutex> _(__m_);
+    __locked_ = false;
+    __cv_.notify_one();
+}
+
+// recursive_timed_mutex
+
+recursive_timed_mutex::recursive_timed_mutex()
+    : __count_(0),
+      __id_{}
+{
+}
+
+recursive_timed_mutex::~recursive_timed_mutex()
+{
+    lock_guard<mutex> _(__m_);
+}
+
+void
+recursive_timed_mutex::lock()
+{
+    __thread_id id = this_thread::get_id();
+    unique_lock<mutex> lk(__m_);
+    if (id ==__id_)
+    {
+        if (__count_ == numeric_limits<size_t>::max())
+            __throw_system_error(EAGAIN, "recursive_timed_mutex lock limit reached");
+        ++__count_;
+        return;
+    }
+    while (__count_ != 0)
+        __cv_.wait(lk);
+    __count_ = 1;
+    __id_ = id;
+}
+
+bool
+recursive_timed_mutex::try_lock() noexcept
+{
+    __thread_id id = this_thread::get_id();
+    unique_lock<mutex> lk(__m_, try_to_lock);
+    if (lk.owns_lock() && (__count_ == 0 || id == __id_))
+    {
+        if (__count_ == numeric_limits<size_t>::max())
+            return false;
+        ++__count_;
+        __id_ = id;
+        return true;
+    }
+    return false;
+}
+
+void
+recursive_timed_mutex::unlock() noexcept
+{
+    unique_lock<mutex> lk(__m_);
+    if (--__count_ == 0)
+    {
+        __id_.__reset();
+        lk.unlock();
+        __cv_.notify_one();
+    }
+}
+
+#endif // !_LIBCPP_HAS_NO_THREADS
+
+// If dispatch_once_f ever handles C++ exceptions, and if one can get to it
+// without illegal macros (unexpected macros not beginning with _UpperCase or
+// __lowercase), and if it stops spinning waiting threads, then call_once should
+// call into dispatch_once_f instead of here. Relevant radar this code needs to
+// keep in sync with:  7741191.
+
+#ifndef _LIBCPP_HAS_NO_THREADS
+static constinit __libcpp_mutex_t mut = _LIBCPP_MUTEX_INITIALIZER;
+static constinit __libcpp_condvar_t cv = _LIBCPP_CONDVAR_INITIALIZER;
+#endif
+
+void __call_once(volatile once_flag::_State_type& flag, void* arg,
+                 void (*func)(void*))
+{
+#if defined(_LIBCPP_HAS_NO_THREADS)
+    if (flag == 0)
+    {
+#ifndef _LIBCPP_HAS_NO_EXCEPTIONS
+        try
+        {
+#endif // _LIBCPP_HAS_NO_EXCEPTIONS
+            flag = 1;
+            func(arg);
+            flag = ~once_flag::_State_type(0);
+#ifndef _LIBCPP_HAS_NO_EXCEPTIONS
+        }
+        catch (...)
+        {
+            flag = 0;
+            throw;
+        }
+#endif // _LIBCPP_HAS_NO_EXCEPTIONS
+    }
+#else // !_LIBCPP_HAS_NO_THREADS
+    __libcpp_mutex_lock(&mut);
+    while (flag == 1)
+        __libcpp_condvar_wait(&cv, &mut);
+    if (flag == 0)
+    {
+#ifndef _LIBCPP_HAS_NO_EXCEPTIONS
+        try
+        {
+#endif // _LIBCPP_HAS_NO_EXCEPTIONS
+            __libcpp_relaxed_store(&flag, once_flag::_State_type(1));
+            __libcpp_mutex_unlock(&mut);
+            func(arg);
+            __libcpp_mutex_lock(&mut);
+            __libcpp_atomic_store(&flag, ~once_flag::_State_type(0),
+                                  _AO_Release);
+            __libcpp_mutex_unlock(&mut);
+            __libcpp_condvar_broadcast(&cv);
+#ifndef _LIBCPP_HAS_NO_EXCEPTIONS
+        }
+        catch (...)
+        {
+            __libcpp_mutex_lock(&mut);
+            __libcpp_relaxed_store(&flag, once_flag::_State_type(0));
+            __libcpp_mutex_unlock(&mut);
+            __libcpp_condvar_broadcast(&cv);
+            throw;
+        }
+#endif // _LIBCPP_HAS_NO_EXCEPTIONS
+    }
+    else
+        __libcpp_mutex_unlock(&mut);
+#endif // !_LIBCPP_HAS_NO_THREADS
+}
+
+_LIBCPP_END_NAMESPACE_STD
+
+_LIBCPP_POP_MACROS

third_party/libcxx/src/mutex_destructor.cpp

@@ -0,0 +1,50 @@
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+// Define ~mutex.
+//
+// On some platforms ~mutex has been made trivial and the definition is only
+// provided for ABI compatibility.
+//
+// In order to avoid ODR violations within libc++ itself, we need to ensure
+// that *nothing* sees the non-trivial mutex declaration. For this reason
+// we re-declare the entire class in this file instead of using
+// _LIBCPP_BUILDING_LIBRARY to change the definition in the headers.
+
+#include <__config>
+#include <__threading_support>
+
+#if !defined(_LIBCPP_HAS_NO_THREADS)
+#  if _LIBCPP_ABI_VERSION == 1 || !defined(_LIBCPP_HAS_TRIVIAL_MUTEX_DESTRUCTION)
+#    define NEEDS_MUTEX_DESTRUCTOR
+#  endif
+#endif
+
+_LIBCPP_BEGIN_NAMESPACE_STD
+
+#ifdef NEEDS_MUTEX_DESTRUCTOR
+class _LIBCPP_TYPE_VIS mutex
+{
+    __libcpp_mutex_t __m_ = _LIBCPP_MUTEX_INITIALIZER;
+
+public:
+    _LIBCPP_ALWAYS_INLINE _LIBCPP_INLINE_VISIBILITY
+    constexpr mutex() = default;
+    mutex(const mutex&) = delete;
+    mutex& operator=(const mutex&) = delete;
+    ~mutex() noexcept;
+};
+
+
+mutex::~mutex() noexcept
+{
+    __libcpp_mutex_destroy(&__m_);
+}
+
+#endif // !_LIBCPP_HAS_NO_THREADS
+_LIBCPP_END_NAMESPACE_STD

third_party/libcxx/src/new.cpp

@@ -0,0 +1,294 @@
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#include <__memory/aligned_alloc.h>
+#include <new>
+#include <stdlib.h>
+
+#include "third_party/libcxx/src/include/atomic_support.h"
+
+#if defined(_LIBCPP_ABI_MICROSOFT)
+#   if !defined(_LIBCPP_ABI_VCRUNTIME)
+#       include "third_party/libcxx/src/support/runtime/new_handler_fallback.ipp"
+#   endif
+#elif defined(LIBCXX_BUILDING_LIBCXXABI)
+#   include <cxxabi.h>
+#elif defined(LIBCXXRT)
+#   include <cxxabi.h>
+#   include "third_party/libcxx/src/support/runtime/new_handler_fallback.ipp"
+#elif defined(__GLIBCXX__)
+    // nothing to do
+#else
+#   include "third_party/libcxx/src/support/runtime/new_handler_fallback.ipp"
+#endif
+
+namespace std
+{
+
+#ifndef __GLIBCXX__
+const nothrow_t nothrow{};
+#endif
+
+#ifndef LIBSTDCXX
+
+void
+__throw_bad_alloc()
+{
+#ifndef _LIBCPP_HAS_NO_EXCEPTIONS
+    throw bad_alloc();
+#else
+    _VSTD::abort();
+#endif
+}
+
+#endif // !LIBSTDCXX
+
+}  // std
+
+#if !defined(__GLIBCXX__) &&                                                   \
+    !defined(_LIBCPP_ABI_VCRUNTIME) &&      \
+    !defined(_LIBCPP_DISABLE_NEW_DELETE_DEFINITIONS)
+
+// Implement all new and delete operators as weak definitions
+// in this shared library, so that they can be overridden by programs
+// that define non-weak copies of the functions.
+
+_LIBCPP_WEAK
+void *
+operator new(std::size_t size) _THROW_BAD_ALLOC
+{
+    if (size == 0)
+        size = 1;
+    void* p;
+    while ((p = ::malloc(size)) == nullptr)
+    {
+        // If malloc fails and there is a new_handler,
+        // call it to try free up memory.
+        std::new_handler nh = std::get_new_handler();
+        if (nh)
+            nh();
+        else
+#ifndef _LIBCPP_HAS_NO_EXCEPTIONS
+            throw std::bad_alloc();
+#else
+            break;
+#endif
+    }
+    return p;
+}
+
+_LIBCPP_WEAK
+void*
+operator new(size_t size, const std::nothrow_t&) noexcept
+{
+    void* p = nullptr;
+#ifndef _LIBCPP_HAS_NO_EXCEPTIONS
+    try
+    {
+#endif // _LIBCPP_HAS_NO_EXCEPTIONS
+        p = ::operator new(size);
+#ifndef _LIBCPP_HAS_NO_EXCEPTIONS
+    }
+    catch (...)
+    {
+    }
+#endif // _LIBCPP_HAS_NO_EXCEPTIONS
+    return p;
+}
+
+_LIBCPP_WEAK
+void*
+operator new[](size_t size) _THROW_BAD_ALLOC
+{
+    return ::operator new(size);
+}
+
+_LIBCPP_WEAK
+void*
+operator new[](size_t size, const std::nothrow_t&) noexcept
+{
+    void* p = nullptr;
+#ifndef _LIBCPP_HAS_NO_EXCEPTIONS
+    try
+    {
+#endif // _LIBCPP_HAS_NO_EXCEPTIONS
+        p = ::operator new[](size);
+#ifndef _LIBCPP_HAS_NO_EXCEPTIONS
+    }
+    catch (...)
+    {
+    }
+#endif // _LIBCPP_HAS_NO_EXCEPTIONS
+    return p;
+}
+
+_LIBCPP_WEAK
+void
+operator delete(void* ptr) noexcept
+{
+    ::free(ptr);
+}
+
+_LIBCPP_WEAK
+void
+operator delete(void* ptr, const std::nothrow_t&) noexcept
+{
+    ::operator delete(ptr);
+}
+
+_LIBCPP_WEAK
+void
+operator delete(void* ptr, size_t) noexcept
+{
+    ::operator delete(ptr);
+}
+
+_LIBCPP_WEAK
+void
+operator delete[] (void* ptr) noexcept
+{
+    ::operator delete(ptr);
+}
+
+_LIBCPP_WEAK
+void
+operator delete[] (void* ptr, const std::nothrow_t&) noexcept
+{
+    ::operator delete[](ptr);
+}
+
+_LIBCPP_WEAK
+void
+operator delete[] (void* ptr, size_t) noexcept
+{
+    ::operator delete[](ptr);
+}
+
+#if !defined(_LIBCPP_HAS_NO_LIBRARY_ALIGNED_ALLOCATION)
+
+_LIBCPP_WEAK
+void *
+operator new(std::size_t size, std::align_val_t alignment) _THROW_BAD_ALLOC
+{
+    if (size == 0)
+        size = 1;
+    if (static_cast<size_t>(alignment) < sizeof(void*))
+      alignment = std::align_val_t(sizeof(void*));
+
+    // Try allocating memory. If allocation fails and there is a new_handler,
+    // call it to try free up memory, and try again until it succeeds, or until
+    // the new_handler decides to terminate.
+    //
+    // If allocation fails and there is no new_handler, we throw bad_alloc
+    // (or return nullptr if exceptions are disabled).
+    void* p;
+    while ((p = std::__libcpp_aligned_alloc(static_cast<std::size_t>(alignment), size)) == nullptr)
+    {
+        std::new_handler nh = std::get_new_handler();
+        if (nh)
+            nh();
+        else {
+#ifndef _LIBCPP_HAS_NO_EXCEPTIONS
+            throw std::bad_alloc();
+#else
+            break;
+#endif
+        }
+    }
+    return p;
+}
+
+_LIBCPP_WEAK
+void*
+operator new(size_t size, std::align_val_t alignment, const std::nothrow_t&) noexcept
+{
+    void* p = nullptr;
+#ifndef _LIBCPP_HAS_NO_EXCEPTIONS
+    try
+    {
+#endif // _LIBCPP_HAS_NO_EXCEPTIONS
+        p = ::operator new(size, alignment);
+#ifndef _LIBCPP_HAS_NO_EXCEPTIONS
+    }
+    catch (...)
+    {
+    }
+#endif // _LIBCPP_HAS_NO_EXCEPTIONS
+    return p;
+}
+
+_LIBCPP_WEAK
+void*
+operator new[](size_t size, std::align_val_t alignment) _THROW_BAD_ALLOC
+{
+    return ::operator new(size, alignment);
+}
+
+_LIBCPP_WEAK
+void*
+operator new[](size_t size, std::align_val_t alignment, const std::nothrow_t&) noexcept
+{
+    void* p = nullptr;
+#ifndef _LIBCPP_HAS_NO_EXCEPTIONS
+    try
+    {
+#endif // _LIBCPP_HAS_NO_EXCEPTIONS
+        p = ::operator new[](size, alignment);
+#ifndef _LIBCPP_HAS_NO_EXCEPTIONS
+    }
+    catch (...)
+    {
+    }
+#endif // _LIBCPP_HAS_NO_EXCEPTIONS
+    return p;
+}
+
+_LIBCPP_WEAK
+void
+operator delete(void* ptr, std::align_val_t) noexcept
+{
+    std::__libcpp_aligned_free(ptr);
+}
+
+_LIBCPP_WEAK
+void
+operator delete(void* ptr, std::align_val_t alignment, const std::nothrow_t&) noexcept
+{
+    ::operator delete(ptr, alignment);
+}
+
+_LIBCPP_WEAK
+void
+operator delete(void* ptr, size_t, std::align_val_t alignment) noexcept
+{
+    ::operator delete(ptr, alignment);
+}
+
+_LIBCPP_WEAK
+void
+operator delete[] (void* ptr, std::align_val_t alignment) noexcept
+{
+    ::operator delete(ptr, alignment);
+}
+
+_LIBCPP_WEAK
+void
+operator delete[] (void* ptr, std::align_val_t alignment, const std::nothrow_t&) noexcept
+{
+    ::operator delete[](ptr, alignment);
+}
+
+_LIBCPP_WEAK
+void
+operator delete[] (void* ptr, size_t, std::align_val_t alignment) noexcept
+{
+    ::operator delete[](ptr, alignment);
+}
+
+#endif // !_LIBCPP_HAS_NO_LIBRARY_ALIGNED_ALLOCATION
+#endif // !__GLIBCXX__ && !_LIBCPP_ABI_VCRUNTIME && !_LIBCPP_DISABLE_NEW_DELETE_DEFINITIONS

third_party/libcxx/src/optional.cpp

@@ -0,0 +1,42 @@
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#include <__availability>
+#include <optional>
+
+namespace std
+{
+
+bad_optional_access::~bad_optional_access() noexcept = default;
+
+const char* bad_optional_access::what() const noexcept {
+  return "bad_optional_access";
+}
+
+} // std
+
+
+#include <experimental/__config>
+
+//  Preserve std::experimental::bad_optional_access for ABI compatibility
+//  Even though it no longer exists in a header file
+_LIBCPP_BEGIN_NAMESPACE_EXPERIMENTAL
+
+class _LIBCPP_EXCEPTION_ABI _LIBCPP_AVAILABILITY_BAD_OPTIONAL_ACCESS bad_optional_access
+  : public std::logic_error
+{
+public:
+  bad_optional_access() : std::logic_error("Bad optional Access") {}
+
+  // Get the key function ~bad_optional_access() into the dylib
+  virtual ~bad_optional_access() noexcept;
+};
+
+bad_optional_access::~bad_optional_access() noexcept = default;
+
+_LIBCPP_END_NAMESPACE_EXPERIMENTAL

third_party/libcxx/src/random.cpp

@@ -0,0 +1,216 @@
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#include <__config>
+
+#if defined(_LIBCPP_USING_WIN32_RANDOM)
+    // Must be defined before including stdlib.h to enable rand_s().
+#   define _CRT_RAND_S
+#endif // defined(_LIBCPP_USING_WIN32_RANDOM)
+
+#include <__system_error/system_error.h>
+#include <limits>
+#include <random>
+
+#include <errno.h>
+#include <stdio.h>
+#include <stdlib.h>
+
+#if defined(_LIBCPP_USING_GETENTROPY)
+#   include <sys/random.h>
+#elif defined(_LIBCPP_USING_DEV_RANDOM)
+#   include <fcntl.h>
+#   include <unistd.h>
+#   if __has_include(<sys/ioctl.h>) && __has_include(<linux/random.h>)
+#       include <sys/ioctl.h>
+#       include <linux/random.h>
+#   endif
+#elif defined(_LIBCPP_USING_NACL_RANDOM)
+#   include <nacl/nacl_random.h>
+#elif defined(_LIBCPP_USING_FUCHSIA_CPRNG)
+#  include <zircon/syscalls.h>
+#endif
+
+
+_LIBCPP_BEGIN_NAMESPACE_STD
+
+#if defined(_LIBCPP_USING_GETENTROPY)
+
+random_device::random_device(const string& __token)
+{
+    if (__token != "/dev/urandom")
+        __throw_system_error(ENOENT, ("random device not supported " + __token).c_str());
+}
+
+random_device::~random_device()
+{
+}
+
+unsigned
+random_device::operator()()
+{
+    unsigned r;
+    size_t n = sizeof(r);
+    int err = getentropy(&r, n);
+    if (err)
+        __throw_system_error(errno, "random_device getentropy failed");
+    return r;
+}
+
+#elif defined(_LIBCPP_USING_ARC4_RANDOM)
+
+random_device::random_device(const string&)
+{
+}
+
+random_device::~random_device()
+{
+}
+
+unsigned
+random_device::operator()()
+{
+    return arc4random();
+}
+
+#elif defined(_LIBCPP_USING_DEV_RANDOM)
+
+random_device::random_device(const string& __token)
+    : __f_(open(__token.c_str(), O_RDONLY))
+{
+    if (__f_ < 0)
+        __throw_system_error(errno, ("random_device failed to open " + __token).c_str());
+}
+
+random_device::~random_device()
+{
+    close(__f_);
+}
+
+unsigned
+random_device::operator()()
+{
+    unsigned r;
+    size_t n = sizeof(r);
+    char* p = reinterpret_cast<char*>(&r);
+    while (n > 0)
+    {
+        ssize_t s = read(__f_, p, n);
+        if (s == 0)
+            __throw_system_error(ENODATA, "random_device got EOF");
+        if (s == -1)
+        {
+            if (errno != EINTR)
+                __throw_system_error(errno, "random_device got an unexpected error");
+            continue;
+        }
+        n -= static_cast<size_t>(s);
+        p += static_cast<size_t>(s);
+    }
+    return r;
+}
+
+#elif defined(_LIBCPP_USING_NACL_RANDOM)
+
+random_device::random_device(const string& __token)
+{
+    if (__token != "/dev/urandom")
+        __throw_system_error(ENOENT, ("random device not supported " + __token).c_str());
+    int error = nacl_secure_random_init();
+    if (error)
+        __throw_system_error(error, ("random device failed to open " + __token).c_str());
+}
+
+random_device::~random_device()
+{
+}
+
+unsigned
+random_device::operator()()
+{
+    unsigned r;
+    size_t n = sizeof(r);
+    size_t bytes_written;
+    int error = nacl_secure_random(&r, n, &bytes_written);
+    if (error != 0)
+        __throw_system_error(error, "random_device failed getting bytes");
+    else if (bytes_written != n)
+        __throw_runtime_error("random_device failed to obtain enough bytes");
+    return r;
+}
+
+#elif defined(_LIBCPP_USING_WIN32_RANDOM)
+
+random_device::random_device(const string& __token)
+{
+    if (__token != "/dev/urandom")
+        __throw_system_error(ENOENT, ("random device not supported " + __token).c_str());
+}
+
+random_device::~random_device()
+{
+}
+
+unsigned
+random_device::operator()()
+{
+    unsigned r;
+    errno_t err = rand_s(&r);
+    if (err)
+        __throw_system_error(err, "random_device rand_s failed.");
+    return r;
+}
+
+#elif defined(_LIBCPP_USING_FUCHSIA_CPRNG)
+
+random_device::random_device(const string& __token) {
+  if (__token != "/dev/urandom")
+    __throw_system_error(ENOENT, ("random device not supported " + __token).c_str());
+}
+
+random_device::~random_device() {}
+
+unsigned random_device::operator()() {
+  // Implicitly link against the vDSO system call ABI without
+  // requiring the final link to specify -lzircon explicitly when
+  // statically linking libc++.
+#  pragma comment(lib, "zircon")
+
+  // The system call cannot fail.  It returns only when the bits are ready.
+  unsigned r;
+  _zx_cprng_draw(&r, sizeof(r));
+  return r;
+}
+
+#else
+#error "Random device not implemented for this architecture"
+#endif
+
+double
+random_device::entropy() const noexcept
+{
+#if defined(_LIBCPP_USING_DEV_RANDOM) && defined(RNDGETENTCNT)
+  int ent;
+  if (::ioctl(__f_, RNDGETENTCNT, &ent) < 0)
+    return 0;
+
+  if (ent < 0)
+    return 0;
+
+  if (ent > std::numeric_limits<result_type>::digits)
+    return std::numeric_limits<result_type>::digits;
+
+  return ent;
+#elif defined(_LIBCPP_USING_ARC4_RANDOM) || defined(_LIBCPP_USING_FUCHSIA_CPRNG)
+  return std::numeric_limits<result_type>::digits;
+#else
+  return 0;
+#endif
+}
+
+_LIBCPP_END_NAMESPACE_STD

third_party/libcxx/src/regex.cpp

@@ -0,0 +1,436 @@
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#include <algorithm>
+#include <iterator>
+#include <regex>
+
+_LIBCPP_BEGIN_NAMESPACE_STD
+
+static
+const char*
+make_error_type_string(regex_constants::error_type ecode)
+{
+    switch (ecode)
+    {
+    case regex_constants::error_collate:
+        return "The expression contained an invalid collating element name.";
+    case regex_constants::error_ctype:
+        return "The expression contained an invalid character class name.";
+    case regex_constants::error_escape:
+        return "The expression contained an invalid escaped character, or a "
+               "trailing escape.";
+    case regex_constants::error_backref:
+        return "The expression contained an invalid back reference.";
+    case regex_constants::error_brack:
+        return "The expression contained mismatched [ and ].";
+    case regex_constants::error_paren:
+        return "The expression contained mismatched ( and ).";
+    case regex_constants::error_brace:
+        return "The expression contained mismatched { and }.";
+    case regex_constants::error_badbrace:
+        return "The expression contained an invalid range in a {} expression.";
+    case regex_constants::error_range:
+        return "The expression contained an invalid character range, "
+               "such as [b-a] in most encodings.";
+    case regex_constants::error_space:
+        return "There was insufficient memory to convert the expression into "
+               "a finite state machine.";
+    case regex_constants::error_badrepeat:
+        return "One of *?+{ was not preceded by a valid regular expression.";
+    case regex_constants::error_complexity:
+        return "The complexity of an attempted match against a regular "
+               "expression exceeded a pre-set level.";
+    case regex_constants::error_stack:
+        return "There was insufficient memory to determine whether the regular "
+               "expression could match the specified character sequence.";
+    case regex_constants::__re_err_grammar:
+        return "An invalid regex grammar has been requested.";
+    case regex_constants::__re_err_empty:
+        return "An empty regex is not allowed in the POSIX grammar.";
+    case regex_constants::__re_err_parse:
+        return "The parser did not consume the entire regular expression.";
+    default:
+        break;
+    }
+    return "Unknown error type";
+}
+
+regex_error::regex_error(regex_constants::error_type ecode)
+    : runtime_error(make_error_type_string(ecode)),
+      __code_(ecode)
+{}
+
+regex_error::~regex_error() throw() {}
+
+namespace {
+
+struct collationnames
+{
+    const char* elem_;
+    char char_;
+};
+
+#if defined(__MVS__) && !defined(__NATIVE_ASCII_F)
+// EBCDIC IBM-1047
+// Sorted via the EBCDIC collating sequence
+const collationnames collatenames[] =
+{
+    {"a", 0x81},
+    {"alert", 0x2f},
+    {"ampersand", 0x50},
+    {"apostrophe", 0x7d},
+    {"asterisk", 0x5c},
+    {"b", 0x82},
+    {"backslash", 0xe0},
+    {"backspace", 0x16},
+    {"c", 0x83},
+    {"carriage-return", 0xd},
+    {"circumflex", 0x5f},
+    {"circumflex-accent", 0x5f},
+    {"colon", 0x7a},
+    {"comma", 0x6b},
+    {"commercial-at", 0x7c},
+    {"d", 0x84},
+    {"dollar-sign", 0x5b},
+    {"e", 0x85},
+    {"eight", 0xf8},
+    {"equals-sign", 0x7e},
+    {"exclamation-mark", 0x5a},
+    {"f", 0x86},
+    {"five", 0xf5},
+    {"form-feed", 0xc},
+    {"four", 0xf4},
+    {"full-stop", 0x4b},
+    {"g", 0x87},
+    {"grave-accent", 0x79},
+    {"greater-than-sign", 0x6e},
+    {"h", 0x88},
+    {"hyphen", 0x60},
+    {"hyphen-minus", 0x60},
+    {"i", 0x89},
+    {"j", 0x91},
+    {"k", 0x92},
+    {"l", 0x93},
+    {"left-brace", 0xc0},
+    {"left-curly-bracket", 0xc0},
+    {"left-parenthesis", 0x4d},
+    {"left-square-bracket", 0xad},
+    {"less-than-sign", 0x4c},
+    {"low-line", 0x6d},
+    {"m", 0x94},
+    {"n", 0x95},
+    {"newline", 0x15},
+    {"nine", 0xf9},
+    {"number-sign", 0x7b},
+    {"o", 0x96},
+    {"one", 0xf1},
+    {"p", 0x97},
+    {"percent-sign", 0x6c},
+    {"period", 0x4b},
+    {"plus-sign", 0x4e},
+    {"q", 0x98},
+    {"question-mark", 0x6f},
+    {"quotation-mark", 0x7f},
+    {"r", 0x99},
+    {"reverse-solidus", 0xe0},
+    {"right-brace", 0xd0},
+    {"right-curly-bracket", 0xd0},
+    {"right-parenthesis", 0x5d},
+    {"right-square-bracket", 0xbd},
+    {"s", 0xa2},
+    {"semicolon", 0x5e},
+    {"seven", 0xf7},
+    {"six", 0xf6},
+    {"slash", 0x61},
+    {"solidus", 0x61},
+    {"space", 0x40},
+    {"t", 0xa3},
+    {"tab", 0x5},
+    {"three", 0xf3},
+    {"tilde", 0xa1},
+    {"two", 0xf2},
+    {"u", 0xa4},
+    {"underscore", 0x6d},
+    {"v", 0xa5},
+    {"vertical-line", 0x4f},
+    {"vertical-tab", 0xb},
+    {"w", 0xa6},
+    {"x", 0xa7},
+    {"y", 0xa8},
+    {"z", 0xa9},
+    {"zero", 0xf0},
+    {"A", 0xc1},
+    {"B", 0xc2},
+    {"C", 0xc3},
+    {"D", 0xc4},
+    {"E", 0xc5},
+    {"F", 0xc6},
+    {"G", 0xc7},
+    {"H", 0xc8},
+    {"I", 0xc9},
+    {"J", 0xd1},
+    {"K", 0xd2},
+    {"L", 0xd3},
+    {"M", 0xd4},
+    {"N", 0xd5},
+    {"NUL", 0},
+    {"O", 0xd6},
+    {"P", 0xd7},
+    {"Q", 0xd8},
+    {"R", 0xd9},
+    {"S", 0xe2},
+    {"T", 0xe3},
+    {"U", 0xe4},
+    {"V", 0xe5},
+    {"W", 0xe6},
+    {"X", 0xe7},
+    {"Y", 0xe8},
+    {"Z", 0xe9}
+};
+#else
+// ASCII
+const collationnames collatenames[] =
+{
+    {"A", 0x41},
+    {"B", 0x42},
+    {"C", 0x43},
+    {"D", 0x44},
+    {"E", 0x45},
+    {"F", 0x46},
+    {"G", 0x47},
+    {"H", 0x48},
+    {"I", 0x49},
+    {"J", 0x4a},
+    {"K", 0x4b},
+    {"L", 0x4c},
+    {"M", 0x4d},
+    {"N", 0x4e},
+    {"NUL", 0x00},
+    {"O", 0x4f},
+    {"P", 0x50},
+    {"Q", 0x51},
+    {"R", 0x52},
+    {"S", 0x53},
+    {"T", 0x54},
+    {"U", 0x55},
+    {"V", 0x56},
+    {"W", 0x57},
+    {"X", 0x58},
+    {"Y", 0x59},
+    {"Z", 0x5a},
+    {"a", 0x61},
+    {"alert", 0x07},
+    {"ampersand", 0x26},
+    {"apostrophe", 0x27},
+    {"asterisk", 0x2a},
+    {"b", 0x62},
+    {"backslash", 0x5c},
+    {"backspace", 0x08},
+    {"c", 0x63},
+    {"carriage-return", 0x0d},
+    {"circumflex", 0x5e},
+    {"circumflex-accent", 0x5e},
+    {"colon", 0x3a},
+    {"comma", 0x2c},
+    {"commercial-at", 0x40},
+    {"d", 0x64},
+    {"dollar-sign", 0x24},
+    {"e", 0x65},
+    {"eight", 0x38},
+    {"equals-sign", 0x3d},
+    {"exclamation-mark", 0x21},
+    {"f", 0x66},
+    {"five", 0x35},
+    {"form-feed", 0x0c},
+    {"four", 0x34},
+    {"full-stop", 0x2e},
+    {"g", 0x67},
+    {"grave-accent", 0x60},
+    {"greater-than-sign", 0x3e},
+    {"h", 0x68},
+    {"hyphen", 0x2d},
+    {"hyphen-minus", 0x2d},
+    {"i", 0x69},
+    {"j", 0x6a},
+    {"k", 0x6b},
+    {"l", 0x6c},
+    {"left-brace", 0x7b},
+    {"left-curly-bracket", 0x7b},
+    {"left-parenthesis", 0x28},
+    {"left-square-bracket", 0x5b},
+    {"less-than-sign", 0x3c},
+    {"low-line", 0x5f},
+    {"m", 0x6d},
+    {"n", 0x6e},
+    {"newline", 0x0a},
+    {"nine", 0x39},
+    {"number-sign", 0x23},
+    {"o", 0x6f},
+    {"one", 0x31},
+    {"p", 0x70},
+    {"percent-sign", 0x25},
+    {"period", 0x2e},
+    {"plus-sign", 0x2b},
+    {"q", 0x71},
+    {"question-mark", 0x3f},
+    {"quotation-mark", 0x22},
+    {"r", 0x72},
+    {"reverse-solidus", 0x5c},
+    {"right-brace", 0x7d},
+    {"right-curly-bracket", 0x7d},
+    {"right-parenthesis", 0x29},
+    {"right-square-bracket", 0x5d},
+    {"s", 0x73},
+    {"semicolon", 0x3b},
+    {"seven", 0x37},
+    {"six", 0x36},
+    {"slash", 0x2f},
+    {"solidus", 0x2f},
+    {"space", 0x20},
+    {"t", 0x74},
+    {"tab", 0x09},
+    {"three", 0x33},
+    {"tilde", 0x7e},
+    {"two", 0x32},
+    {"u", 0x75},
+    {"underscore", 0x5f},
+    {"v", 0x76},
+    {"vertical-line", 0x7c},
+    {"vertical-tab", 0x0b},
+    {"w", 0x77},
+    {"x", 0x78},
+    {"y", 0x79},
+    {"z", 0x7a},
+    {"zero", 0x30}
+};
+#endif
+
+struct classnames
+{
+    const char* elem_;
+    regex_traits<char>::char_class_type mask_;
+};
+
+const classnames ClassNames[] =
+{
+    {"alnum",  ctype_base::alnum},
+    {"alpha",  ctype_base::alpha},
+    {"blank",  ctype_base::blank},
+    {"cntrl",  ctype_base::cntrl},
+    {"d",      ctype_base::digit},
+    {"digit",  ctype_base::digit},
+    {"graph",  ctype_base::graph},
+    {"lower",  ctype_base::lower},
+    {"print",  ctype_base::print},
+    {"punct",  ctype_base::punct},
+    {"s",      ctype_base::space},
+    {"space",  ctype_base::space},
+    {"upper",  ctype_base::upper},
+    {"w",      regex_traits<char>::__regex_word},
+    {"xdigit", ctype_base::xdigit}
+};
+
+struct use_strcmp
+{
+    bool operator()(const collationnames& x, const char* y)
+        {return strcmp(x.elem_, y) < 0;}
+    bool operator()(const classnames& x, const char* y)
+        {return strcmp(x.elem_, y) < 0;}
+};
+
+}
+
+string
+__get_collation_name(const char* s)
+{
+    const collationnames* i =
+            _VSTD::lower_bound(begin(collatenames), end(collatenames), s, use_strcmp());
+    string r;
+    if (i != end(collatenames) && strcmp(s, i->elem_) == 0)
+        r = char(i->char_);
+    return r;
+}
+
+regex_traits<char>::char_class_type
+__get_classname(const char* s, bool __icase)
+{
+    const classnames* i =
+            _VSTD::lower_bound(begin(ClassNames), end(ClassNames), s, use_strcmp());
+    regex_traits<char>::char_class_type r = 0;
+    if (i != end(ClassNames) && strcmp(s, i->elem_) == 0)
+    {
+        r = i->mask_;
+        if (r == regex_traits<char>::__regex_word)
+            r |= ctype_base::alnum | ctype_base::upper | ctype_base::lower;
+        else if (__icase)
+        {
+            if (r & (ctype_base::lower | ctype_base::upper))
+                r |= ctype_base::alpha;
+        }
+    }
+    return r;
+}
+
+template <>
+void
+__match_any_but_newline<char>::__exec(__state& __s) const
+{
+    if (__s.__current_ != __s.__last_)
+    {
+        switch (*__s.__current_)
+        {
+        case '\r':
+        case '\n':
+            __s.__do_ = __state::__reject;
+            __s.__node_ = nullptr;
+            break;
+        default:
+            __s.__do_ = __state::__accept_and_consume;
+            ++__s.__current_;
+            __s.__node_ = this->first();
+            break;
+        }
+    }
+    else
+    {
+        __s.__do_ = __state::__reject;
+        __s.__node_ = nullptr;
+    }
+}
+
+template <>
+void
+__match_any_but_newline<wchar_t>::__exec(__state& __s) const
+{
+    if (__s.__current_ != __s.__last_)
+    {
+        switch (*__s.__current_)
+        {
+        case '\r':
+        case '\n':
+        case 0x2028:
+        case 0x2029:
+            __s.__do_ = __state::__reject;
+            __s.__node_ = nullptr;
+            break;
+        default:
+            __s.__do_ = __state::__accept_and_consume;
+            ++__s.__current_;
+            __s.__node_ = this->first();
+            break;
+        }
+    }
+    else
+    {
+        __s.__do_ = __state::__reject;
+        __s.__node_ = nullptr;
+    }
+}
+
+_LIBCPP_END_NAMESPACE_STD

third_party/libcxx/src/ryu/README.txt

@@ -0,0 +1,11 @@
+The code in this directory is based on Ulf Adams's work. The upstream for the
+code is:
+
+https://github.com/ulfjack/ryu/tree/59661c3/ryu
+
+The code has been adapted by Stephan T. Lavavej of Microsoft for usage in
+std::to_chars. This code has been contributed by Microsoft for inclusion in
+libc++.
+
+The code in this directory has a different coding style than other parts to
+minimize the number of changes by both upstream sources.

third_party/libcxx/src/ryu/d2fixed.cpp

@@ -0,0 +1,669 @@
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+// Copyright (c) Microsoft Corporation.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+
+// Copyright 2018 Ulf Adams
+// Copyright (c) Microsoft Corporation. All rights reserved.
+
+// Boost Software License - Version 1.0 - August 17th, 2003
+
+// Permission is hereby granted, free of charge, to any person or organization
+// obtaining a copy of the software and accompanying documentation covered by
+// this license (the "Software") to use, reproduce, display, distribute,
+// execute, and transmit the Software, and to prepare derivative works of the
+// Software, and to permit third-parties to whom the Software is furnished to
+// do so, all subject to the following:
+
+// The copyright notices in the Software and this entire statement, including
+// the above license grant, this restriction and the following disclaimer,
+// must be included in all copies of the Software, in whole or in part, and
+// all derivative works of the Software, unless such copies or derivative
+// works are solely in the form of machine-executable object code generated by
+// a source language processor.
+
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+// FITNESS FOR A PARTICULAR PURPOSE, TITLE AND NON-INFRINGEMENT. IN NO EVENT
+// SHALL THE COPYRIGHT HOLDERS OR ANYONE DISTRIBUTING THE SOFTWARE BE LIABLE
+// FOR ANY DAMAGES OR OTHER LIABILITY, WHETHER IN CONTRACT, TORT OR OTHERWISE,
+// ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
+// DEALINGS IN THE SOFTWARE.
+
+// Avoid formatting to keep the changes with the original code minimal.
+// clang-format off
+
+#include <__assert>
+#include <__config>
+#include <charconv>
+#include <cstring>
+
+#include "third_party/libcxx/src/include/ryu/common.h"
+#include "third_party/libcxx/src/include/ryu/d2fixed.h"
+#include "third_party/libcxx/src/include/ryu/d2fixed_full_table.h"
+#include "third_party/libcxx/src/include/ryu/d2s.h"
+#include "third_party/libcxx/src/include/ryu/d2s_intrinsics.h"
+#include "third_party/libcxx/src/include/ryu/digit_table.h"
+
+_LIBCPP_BEGIN_NAMESPACE_STD
+
+inline constexpr int __POW10_ADDITIONAL_BITS = 120;
+
+#ifdef _LIBCPP_INTRINSIC128
+// Returns the low 64 bits of the high 128 bits of the 256-bit product of a and b.
+[[nodiscard]] _LIBCPP_HIDE_FROM_ABI inline uint64_t __umul256_hi128_lo64(
+  const uint64_t __aHi, const uint64_t __aLo, const uint64_t __bHi, const uint64_t __bLo) {
+  uint64_t __b00Hi;
+  const uint64_t __b00Lo = __ryu_umul128(__aLo, __bLo, &__b00Hi);
+  uint64_t __b01Hi;
+  const uint64_t __b01Lo = __ryu_umul128(__aLo, __bHi, &__b01Hi);
+  uint64_t __b10Hi;
+  const uint64_t __b10Lo = __ryu_umul128(__aHi, __bLo, &__b10Hi);
+  uint64_t __b11Hi;
+  const uint64_t __b11Lo = __ryu_umul128(__aHi, __bHi, &__b11Hi);
+  (void) __b00Lo; // unused
+  (void) __b11Hi; // unused
+  const uint64_t __temp1Lo = __b10Lo + __b00Hi;
+  const uint64_t __temp1Hi = __b10Hi + (__temp1Lo < __b10Lo);
+  const uint64_t __temp2Lo = __b01Lo + __temp1Lo;
+  const uint64_t __temp2Hi = __b01Hi + (__temp2Lo < __b01Lo);
+  return __b11Lo + __temp1Hi + __temp2Hi;
+}
+
+[[nodiscard]] _LIBCPP_HIDE_FROM_ABI inline uint32_t __uint128_mod1e9(const uint64_t __vHi, const uint64_t __vLo) {
+  // After multiplying, we're going to shift right by 29, then truncate to uint32_t.
+  // This means that we need only 29 + 32 = 61 bits, so we can truncate to uint64_t before shifting.
+  const uint64_t __multiplied = __umul256_hi128_lo64(__vHi, __vLo, 0x89705F4136B4A597u, 0x31680A88F8953031u);
+
+  // For uint32_t truncation, see the __mod1e9() comment in d2s_intrinsics.h.
+  const uint32_t __shifted = static_cast<uint32_t>(__multiplied >> 29);
+
+  return static_cast<uint32_t>(__vLo) - 1000000000 * __shifted;
+}
+#endif // ^^^ intrinsics available ^^^
+
+[[nodiscard]] _LIBCPP_HIDE_FROM_ABI inline uint32_t __mulShift_mod1e9(const uint64_t __m, const uint64_t* const __mul, const int32_t __j) {
+  uint64_t __high0;                                               // 64
+  const uint64_t __low0 = __ryu_umul128(__m, __mul[0], &__high0); // 0
+  uint64_t __high1;                                               // 128
+  const uint64_t __low1 = __ryu_umul128(__m, __mul[1], &__high1); // 64
+  uint64_t __high2;                                               // 192
+  const uint64_t __low2 = __ryu_umul128(__m, __mul[2], &__high2); // 128
+  const uint64_t __s0low = __low0;                  // 0
+  (void) __s0low; // unused
+  const uint64_t __s0high = __low1 + __high0;       // 64
+  const uint32_t __c1 = __s0high < __low1;
+  const uint64_t __s1low = __low2 + __high1 + __c1; // 128
+  const uint32_t __c2 = __s1low < __low2; // __high1 + __c1 can't overflow, so compare against __low2
+  const uint64_t __s1high = __high2 + __c2;         // 192
+  _LIBCPP_ASSERT(__j >= 128, "");
+  _LIBCPP_ASSERT(__j <= 180, "");
+#ifdef _LIBCPP_INTRINSIC128
+  const uint32_t __dist = static_cast<uint32_t>(__j - 128); // __dist: [0, 52]
+  const uint64_t __shiftedhigh = __s1high >> __dist;
+  const uint64_t __shiftedlow = __ryu_shiftright128(__s1low, __s1high, __dist);
+  return __uint128_mod1e9(__shiftedhigh, __shiftedlow);
+#else // ^^^ intrinsics available ^^^ / vvv intrinsics unavailable vvv
+  if (__j < 160) { // __j: [128, 160)
+    const uint64_t __r0 = __mod1e9(__s1high);
+    const uint64_t __r1 = __mod1e9((__r0 << 32) | (__s1low >> 32));
+    const uint64_t __r2 = ((__r1 << 32) | (__s1low & 0xffffffff));
+    return __mod1e9(__r2 >> (__j - 128));
+  } else { // __j: [160, 192)
+    const uint64_t __r0 = __mod1e9(__s1high);
+    const uint64_t __r1 = ((__r0 << 32) | (__s1low >> 32));
+    return __mod1e9(__r1 >> (__j - 160));
+  }
+#endif // ^^^ intrinsics unavailable ^^^
+}
+
+void __append_n_digits(const uint32_t __olength, uint32_t __digits, char* const __result) {
+  uint32_t __i = 0;
+  while (__digits >= 10000) {
+#ifdef __clang__ // TRANSITION, LLVM-38217
+    const uint32_t __c = __digits - 10000 * (__digits / 10000);
+#else
+    const uint32_t __c = __digits % 10000;
+#endif
+    __digits /= 10000;
+    const uint32_t __c0 = (__c % 100) << 1;
+    const uint32_t __c1 = (__c / 100) << 1;
+    std::memcpy(__result + __olength - __i - 2, __DIGIT_TABLE + __c0, 2);
+    std::memcpy(__result + __olength - __i - 4, __DIGIT_TABLE + __c1, 2);
+    __i += 4;
+  }
+  if (__digits >= 100) {
+    const uint32_t __c = (__digits % 100) << 1;
+    __digits /= 100;
+    std::memcpy(__result + __olength - __i - 2, __DIGIT_TABLE + __c, 2);
+    __i += 2;
+  }
+  if (__digits >= 10) {
+    const uint32_t __c = __digits << 1;
+    std::memcpy(__result + __olength - __i - 2, __DIGIT_TABLE + __c, 2);
+  } else {
+    __result[0] = static_cast<char>('0' + __digits);
+  }
+}
+
+_LIBCPP_HIDE_FROM_ABI inline void __append_d_digits(const uint32_t __olength, uint32_t __digits, char* const __result) {
+  uint32_t __i = 0;
+  while (__digits >= 10000) {
+#ifdef __clang__ // TRANSITION, LLVM-38217
+    const uint32_t __c = __digits - 10000 * (__digits / 10000);
+#else
+    const uint32_t __c = __digits % 10000;
+#endif
+    __digits /= 10000;
+    const uint32_t __c0 = (__c % 100) << 1;
+    const uint32_t __c1 = (__c / 100) << 1;
+    std::memcpy(__result + __olength + 1 - __i - 2, __DIGIT_TABLE + __c0, 2);
+    std::memcpy(__result + __olength + 1 - __i - 4, __DIGIT_TABLE + __c1, 2);
+    __i += 4;
+  }
+  if (__digits >= 100) {
+    const uint32_t __c = (__digits % 100) << 1;
+    __digits /= 100;
+    std::memcpy(__result + __olength + 1 - __i - 2, __DIGIT_TABLE + __c, 2);
+    __i += 2;
+  }
+  if (__digits >= 10) {
+    const uint32_t __c = __digits << 1;
+    __result[2] = __DIGIT_TABLE[__c + 1];
+    __result[1] = '.';
+    __result[0] = __DIGIT_TABLE[__c];
+  } else {
+    __result[1] = '.';
+    __result[0] = static_cast<char>('0' + __digits);
+  }
+}
+
+_LIBCPP_HIDE_FROM_ABI inline void __append_c_digits(const uint32_t __count, uint32_t __digits, char* const __result) {
+  uint32_t __i = 0;
+  for (; __i < __count - 1; __i += 2) {
+    const uint32_t __c = (__digits % 100) << 1;
+    __digits /= 100;
+    std::memcpy(__result + __count - __i - 2, __DIGIT_TABLE + __c, 2);
+  }
+  if (__i < __count) {
+    const char __c = static_cast<char>('0' + (__digits % 10));
+    __result[__count - __i - 1] = __c;
+  }
+}
+
+void __append_nine_digits(uint32_t __digits, char* const __result) {
+  if (__digits == 0) {
+    std::memset(__result, '0', 9);
+    return;
+  }
+
+  for (uint32_t __i = 0; __i < 5; __i += 4) {
+#ifdef __clang__ // TRANSITION, LLVM-38217
+    const uint32_t __c = __digits - 10000 * (__digits / 10000);
+#else
+    const uint32_t __c = __digits % 10000;
+#endif
+    __digits /= 10000;
+    const uint32_t __c0 = (__c % 100) << 1;
+    const uint32_t __c1 = (__c / 100) << 1;
+    std::memcpy(__result + 7 - __i, __DIGIT_TABLE + __c0, 2);
+    std::memcpy(__result + 5 - __i, __DIGIT_TABLE + __c1, 2);
+  }
+  __result[0] = static_cast<char>('0' + __digits);
+}
+
+[[nodiscard]] _LIBCPP_HIDE_FROM_ABI inline uint32_t __indexForExponent(const uint32_t __e) {
+  return (__e + 15) / 16;
+}
+
+[[nodiscard]] _LIBCPP_HIDE_FROM_ABI inline uint32_t __pow10BitsForIndex(const uint32_t __idx) {
+  return 16 * __idx + __POW10_ADDITIONAL_BITS;
+}
+
+[[nodiscard]] _LIBCPP_HIDE_FROM_ABI inline uint32_t __lengthForIndex(const uint32_t __idx) {
+  // +1 for ceil, +16 for mantissa, +8 to round up when dividing by 9
+  return (__log10Pow2(16 * static_cast<int32_t>(__idx)) + 1 + 16 + 8) / 9;
+}
+
+[[nodiscard]] to_chars_result __d2fixed_buffered_n(char* _First, char* const _Last, const double __d,
+  const uint32_t __precision) {
+  char* const _Original_first = _First;
+
+  const uint64_t __bits = __double_to_bits(__d);
+
+  // Case distinction; exit early for the easy cases.
+  if (__bits == 0) {
+    const int32_t _Total_zero_length = 1 // leading zero
+      + static_cast<int32_t>(__precision != 0) // possible decimal point
+      + static_cast<int32_t>(__precision); // zeroes after decimal point
+
+    if (_Last - _First < _Total_zero_length) {
+      return { _Last, errc::value_too_large };
+    }
+
+    *_First++ = '0';
+    if (__precision > 0) {
+      *_First++ = '.';
+      std::memset(_First, '0', __precision);
+      _First += __precision;
+    }
+    return { _First, errc{} };
+  }
+
+  // Decode __bits into mantissa and exponent.
+  const uint64_t __ieeeMantissa = __bits & ((1ull << __DOUBLE_MANTISSA_BITS) - 1);
+  const uint32_t __ieeeExponent = static_cast<uint32_t>(__bits >> __DOUBLE_MANTISSA_BITS);
+
+  int32_t __e2;
+  uint64_t __m2;
+  if (__ieeeExponent == 0) {
+    __e2 = 1 - __DOUBLE_BIAS - __DOUBLE_MANTISSA_BITS;
+    __m2 = __ieeeMantissa;
+  } else {
+    __e2 = static_cast<int32_t>(__ieeeExponent) - __DOUBLE_BIAS - __DOUBLE_MANTISSA_BITS;
+    __m2 = (1ull << __DOUBLE_MANTISSA_BITS) | __ieeeMantissa;
+  }
+
+  bool __nonzero = false;
+  if (__e2 >= -52) {
+    const uint32_t __idx = __e2 < 0 ? 0 : __indexForExponent(static_cast<uint32_t>(__e2));
+    const uint32_t __p10bits = __pow10BitsForIndex(__idx);
+    const int32_t __len = static_cast<int32_t>(__lengthForIndex(__idx));
+    for (int32_t __i = __len - 1; __i >= 0; --__i) {
+      const uint32_t __j = __p10bits - __e2;
+      // Temporary: __j is usually around 128, and by shifting a bit, we push it to 128 or above, which is
+      // a slightly faster code path in __mulShift_mod1e9. Instead, we can just increase the multipliers.
+      const uint32_t __digits = __mulShift_mod1e9(__m2 << 8, __POW10_SPLIT[__POW10_OFFSET[__idx] + __i],
+        static_cast<int32_t>(__j + 8));
+      if (__nonzero) {
+        if (_Last - _First < 9) {
+          return { _Last, errc::value_too_large };
+        }
+        __append_nine_digits(__digits, _First);
+        _First += 9;
+      } else if (__digits != 0) {
+        const uint32_t __olength = __decimalLength9(__digits);
+        if (_Last - _First < static_cast<ptrdiff_t>(__olength)) {
+          return { _Last, errc::value_too_large };
+        }
+        __append_n_digits(__olength, __digits, _First);
+        _First += __olength;
+        __nonzero = true;
+      }
+    }
+  }
+  if (!__nonzero) {
+    if (_First == _Last) {
+      return { _Last, errc::value_too_large };
+    }
+    *_First++ = '0';
+  }
+  if (__precision > 0) {
+    if (_First == _Last) {
+      return { _Last, errc::value_too_large };
+    }
+    *_First++ = '.';
+  }
+  if (__e2 < 0) {
+    const int32_t __idx = -__e2 / 16;
+    const uint32_t __blocks = __precision / 9 + 1;
+    // 0 = don't round up; 1 = round up unconditionally; 2 = round up if odd.
+    int __roundUp = 0;
+    uint32_t __i = 0;
+    if (__blocks <= __MIN_BLOCK_2[__idx]) {
+      __i = __blocks;
+      if (_Last - _First < static_cast<ptrdiff_t>(__precision)) {
+        return { _Last, errc::value_too_large };
+      }
+      std::memset(_First, '0', __precision);
+      _First += __precision;
+    } else if (__i < __MIN_BLOCK_2[__idx]) {
+      __i = __MIN_BLOCK_2[__idx];
+      if (_Last - _First < static_cast<ptrdiff_t>(9 * __i)) {
+        return { _Last, errc::value_too_large };
+      }
+      std::memset(_First, '0', 9 * __i);
+      _First += 9 * __i;
+    }
+    for (; __i < __blocks; ++__i) {
+      const int32_t __j = __ADDITIONAL_BITS_2 + (-__e2 - 16 * __idx);
+      const uint32_t __p = __POW10_OFFSET_2[__idx] + __i - __MIN_BLOCK_2[__idx];
+      if (__p >= __POW10_OFFSET_2[__idx + 1]) {
+        // If the remaining digits are all 0, then we might as well use memset.
+        // No rounding required in this case.
+        const uint32_t __fill = __precision - 9 * __i;
+        if (_Last - _First < static_cast<ptrdiff_t>(__fill)) {
+          return { _Last, errc::value_too_large };
+        }
+        std::memset(_First, '0', __fill);
+        _First += __fill;
+        break;
+      }
+      // Temporary: __j is usually around 128, and by shifting a bit, we push it to 128 or above, which is
+      // a slightly faster code path in __mulShift_mod1e9. Instead, we can just increase the multipliers.
+      uint32_t __digits = __mulShift_mod1e9(__m2 << 8, __POW10_SPLIT_2[__p], __j + 8);
+      if (__i < __blocks - 1) {
+        if (_Last - _First < 9) {
+          return { _Last, errc::value_too_large };
+        }
+        __append_nine_digits(__digits, _First);
+        _First += 9;
+      } else {
+        const uint32_t __maximum = __precision - 9 * __i;
+        uint32_t __lastDigit = 0;
+        for (uint32_t __k = 0; __k < 9 - __maximum; ++__k) {
+          __lastDigit = __digits % 10;
+          __digits /= 10;
+        }
+        if (__lastDigit != 5) {
+          __roundUp = __lastDigit > 5;
+        } else {
+          // Is m * 10^(additionalDigits + 1) / 2^(-__e2) integer?
+          const int32_t __requiredTwos = -__e2 - static_cast<int32_t>(__precision) - 1;
+          const bool __trailingZeros = __requiredTwos <= 0
+            || (__requiredTwos < 60 && __multipleOfPowerOf2(__m2, static_cast<uint32_t>(__requiredTwos)));
+          __roundUp = __trailingZeros ? 2 : 1;
+        }
+        if (__maximum > 0) {
+          if (_Last - _First < static_cast<ptrdiff_t>(__maximum)) {
+            return { _Last, errc::value_too_large };
+          }
+          __append_c_digits(__maximum, __digits, _First);
+          _First += __maximum;
+        }
+        break;
+      }
+    }
+    if (__roundUp != 0) {
+      char* _Round = _First;
+      char* _Dot = _Last;
+      while (true) {
+        if (_Round == _Original_first) {
+          _Round[0] = '1';
+          if (_Dot != _Last) {
+            _Dot[0] = '0';
+            _Dot[1] = '.';
+          }
+          if (_First == _Last) {
+            return { _Last, errc::value_too_large };
+          }
+          *_First++ = '0';
+          break;
+        }
+        --_Round;
+        const char __c = _Round[0];
+        if (__c == '.') {
+          _Dot = _Round;
+        } else if (__c == '9') {
+          _Round[0] = '0';
+          __roundUp = 1;
+        } else {
+          if (__roundUp == 1 || __c % 2 != 0) {
+            _Round[0] = __c + 1;
+          }
+          break;
+        }
+      }
+    }
+  } else {
+    if (_Last - _First < static_cast<ptrdiff_t>(__precision)) {
+      return { _Last, errc::value_too_large };
+    }
+    std::memset(_First, '0', __precision);
+    _First += __precision;
+  }
+  return { _First, errc{} };
+}
+
+[[nodiscard]] to_chars_result __d2exp_buffered_n(char* _First, char* const _Last, const double __d,
+  uint32_t __precision) {
+  char* const _Original_first = _First;
+
+  const uint64_t __bits = __double_to_bits(__d);
+
+  // Case distinction; exit early for the easy cases.
+  if (__bits == 0) {
+    const int32_t _Total_zero_length = 1 // leading zero
+      + static_cast<int32_t>(__precision != 0) // possible decimal point
+      + static_cast<int32_t>(__precision) // zeroes after decimal point
+      + 4; // "e+00"
+    if (_Last - _First < _Total_zero_length) {
+      return { _Last, errc::value_too_large };
+    }
+    *_First++ = '0';
+    if (__precision > 0) {
+      *_First++ = '.';
+      std::memset(_First, '0', __precision);
+      _First += __precision;
+    }
+    std::memcpy(_First, "e+00", 4);
+    _First += 4;
+    return { _First, errc{} };
+  }
+
+  // Decode __bits into mantissa and exponent.
+  const uint64_t __ieeeMantissa = __bits & ((1ull << __DOUBLE_MANTISSA_BITS) - 1);
+  const uint32_t __ieeeExponent = static_cast<uint32_t>(__bits >> __DOUBLE_MANTISSA_BITS);
+
+  int32_t __e2;
+  uint64_t __m2;
+  if (__ieeeExponent == 0) {
+    __e2 = 1 - __DOUBLE_BIAS - __DOUBLE_MANTISSA_BITS;
+    __m2 = __ieeeMantissa;
+  } else {
+    __e2 = static_cast<int32_t>(__ieeeExponent) - __DOUBLE_BIAS - __DOUBLE_MANTISSA_BITS;
+    __m2 = (1ull << __DOUBLE_MANTISSA_BITS) | __ieeeMantissa;
+  }
+
+  const bool __printDecimalPoint = __precision > 0;
+  ++__precision;
+  uint32_t __digits = 0;
+  uint32_t __printedDigits = 0;
+  uint32_t __availableDigits = 0;
+  int32_t __exp = 0;
+  if (__e2 >= -52) {
+    const uint32_t __idx = __e2 < 0 ? 0 : __indexForExponent(static_cast<uint32_t>(__e2));
+    const uint32_t __p10bits = __pow10BitsForIndex(__idx);
+    const int32_t __len = static_cast<int32_t>(__lengthForIndex(__idx));
+    for (int32_t __i = __len - 1; __i >= 0; --__i) {
+      const uint32_t __j = __p10bits - __e2;
+      // Temporary: __j is usually around 128, and by shifting a bit, we push it to 128 or above, which is
+      // a slightly faster code path in __mulShift_mod1e9. Instead, we can just increase the multipliers.
+      __digits = __mulShift_mod1e9(__m2 << 8, __POW10_SPLIT[__POW10_OFFSET[__idx] + __i],
+        static_cast<int32_t>(__j + 8));
+      if (__printedDigits != 0) {
+        if (__printedDigits + 9 > __precision) {
+          __availableDigits = 9;
+          break;
+        }
+        if (_Last - _First < 9) {
+          return { _Last, errc::value_too_large };
+        }
+        __append_nine_digits(__digits, _First);
+        _First += 9;
+        __printedDigits += 9;
+      } else if (__digits != 0) {
+        __availableDigits = __decimalLength9(__digits);
+        __exp = __i * 9 + static_cast<int32_t>(__availableDigits) - 1;
+        if (__availableDigits > __precision) {
+          break;
+        }
+        if (__printDecimalPoint) {
+          if (_Last - _First < static_cast<ptrdiff_t>(__availableDigits + 1)) {
+            return { _Last, errc::value_too_large };
+          }
+          __append_d_digits(__availableDigits, __digits, _First);
+          _First += __availableDigits + 1; // +1 for decimal point
+        } else {
+          if (_First == _Last) {
+            return { _Last, errc::value_too_large };
+          }
+          *_First++ = static_cast<char>('0' + __digits);
+        }
+        __printedDigits = __availableDigits;
+        __availableDigits = 0;
+      }
+    }
+  }
+
+  if (__e2 < 0 && __availableDigits == 0) {
+    const int32_t __idx = -__e2 / 16;
+    for (int32_t __i = __MIN_BLOCK_2[__idx]; __i < 200; ++__i) {
+      const int32_t __j = __ADDITIONAL_BITS_2 + (-__e2 - 16 * __idx);
+      const uint32_t __p = __POW10_OFFSET_2[__idx] + static_cast<uint32_t>(__i) - __MIN_BLOCK_2[__idx];
+      // Temporary: __j is usually around 128, and by shifting a bit, we push it to 128 or above, which is
+      // a slightly faster code path in __mulShift_mod1e9. Instead, we can just increase the multipliers.
+      __digits = (__p >= __POW10_OFFSET_2[__idx + 1]) ? 0 : __mulShift_mod1e9(__m2 << 8, __POW10_SPLIT_2[__p], __j + 8);
+      if (__printedDigits != 0) {
+        if (__printedDigits + 9 > __precision) {
+          __availableDigits = 9;
+          break;
+        }
+        if (_Last - _First < 9) {
+          return { _Last, errc::value_too_large };
+        }
+        __append_nine_digits(__digits, _First);
+        _First += 9;
+        __printedDigits += 9;
+      } else if (__digits != 0) {
+        __availableDigits = __decimalLength9(__digits);
+        __exp = -(__i + 1) * 9 + static_cast<int32_t>(__availableDigits) - 1;
+        if (__availableDigits > __precision) {
+          break;
+        }
+        if (__printDecimalPoint) {
+          if (_Last - _First < static_cast<ptrdiff_t>(__availableDigits + 1)) {
+            return { _Last, errc::value_too_large };
+          }
+          __append_d_digits(__availableDigits, __digits, _First);
+          _First += __availableDigits + 1; // +1 for decimal point
+        } else {
+          if (_First == _Last) {
+            return { _Last, errc::value_too_large };
+          }
+          *_First++ = static_cast<char>('0' + __digits);
+        }
+        __printedDigits = __availableDigits;
+        __availableDigits = 0;
+      }
+    }
+  }
+
+  const uint32_t __maximum = __precision - __printedDigits;
+  if (__availableDigits == 0) {
+    __digits = 0;
+  }
+  uint32_t __lastDigit = 0;
+  if (__availableDigits > __maximum) {
+    for (uint32_t __k = 0; __k < __availableDigits - __maximum; ++__k) {
+      __lastDigit = __digits % 10;
+      __digits /= 10;
+    }
+  }
+  // 0 = don't round up; 1 = round up unconditionally; 2 = round up if odd.
+  int __roundUp = 0;
+  if (__lastDigit != 5) {
+    __roundUp = __lastDigit > 5;
+  } else {
+    // Is m * 2^__e2 * 10^(__precision + 1 - __exp) integer?
+    // __precision was already increased by 1, so we don't need to write + 1 here.
+    const int32_t __rexp = static_cast<int32_t>(__precision) - __exp;
+    const int32_t __requiredTwos = -__e2 - __rexp;
+    bool __trailingZeros = __requiredTwos <= 0
+      || (__requiredTwos < 60 && __multipleOfPowerOf2(__m2, static_cast<uint32_t>(__requiredTwos)));
+    if (__rexp < 0) {
+      const int32_t __requiredFives = -__rexp;
+      __trailingZeros = __trailingZeros && __multipleOfPowerOf5(__m2, static_cast<uint32_t>(__requiredFives));
+    }
+    __roundUp = __trailingZeros ? 2 : 1;
+  }
+  if (__printedDigits != 0) {
+    if (_Last - _First < static_cast<ptrdiff_t>(__maximum)) {
+      return { _Last, errc::value_too_large };
+    }
+    if (__digits == 0) {
+      std::memset(_First, '0', __maximum);
+    } else {
+      __append_c_digits(__maximum, __digits, _First);
+    }
+    _First += __maximum;
+  } else {
+    if (__printDecimalPoint) {
+      if (_Last - _First < static_cast<ptrdiff_t>(__maximum + 1)) {
+        return { _Last, errc::value_too_large };
+      }
+      __append_d_digits(__maximum, __digits, _First);
+      _First += __maximum + 1; // +1 for decimal point
+    } else {
+      if (_First == _Last) {
+        return { _Last, errc::value_too_large };
+      }
+      *_First++ = static_cast<char>('0' + __digits);
+    }
+  }
+  if (__roundUp != 0) {
+    char* _Round = _First;
+    while (true) {
+      if (_Round == _Original_first) {
+        _Round[0] = '1';
+        ++__exp;
+        break;
+      }
+      --_Round;
+      const char __c = _Round[0];
+      if (__c == '.') {
+        // Keep going.
+      } else if (__c == '9') {
+        _Round[0] = '0';
+        __roundUp = 1;
+      } else {
+        if (__roundUp == 1 || __c % 2 != 0) {
+          _Round[0] = __c + 1;
+        }
+        break;
+      }
+    }
+  }
+
+  char _Sign_character;
+
+  if (__exp < 0) {
+    _Sign_character = '-';
+    __exp = -__exp;
+  } else {
+    _Sign_character = '+';
+  }
+
+  const int _Exponent_part_length = __exp >= 100
+    ? 5 // "e+NNN"
+    : 4; // "e+NN"
+
+  if (_Last - _First < _Exponent_part_length) {
+    return { _Last, errc::value_too_large };
+  }
+
+  *_First++ = 'e';
+  *_First++ = _Sign_character;
+
+  if (__exp >= 100) {
+    const int32_t __c = __exp % 10;
+    std::memcpy(_First, __DIGIT_TABLE + 2 * (__exp / 10), 2);
+    _First[2] = static_cast<char>('0' + __c);
+    _First += 3;
+  } else {
+    std::memcpy(_First, __DIGIT_TABLE + 2 * __exp, 2);
+    _First += 2;
+  }
+
+  return { _First, errc{} };
+}
+
+_LIBCPP_END_NAMESPACE_STD
+
+// clang-format on

third_party/libcxx/src/ryu/d2s.cpp

@@ -0,0 +1,783 @@
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+// Copyright (c) Microsoft Corporation.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+
+// Copyright 2018 Ulf Adams
+// Copyright (c) Microsoft Corporation. All rights reserved.
+
+// Boost Software License - Version 1.0 - August 17th, 2003
+
+// Permission is hereby granted, free of charge, to any person or organization
+// obtaining a copy of the software and accompanying documentation covered by
+// this license (the "Software") to use, reproduce, display, distribute,
+// execute, and transmit the Software, and to prepare derivative works of the
+// Software, and to permit third-parties to whom the Software is furnished to
+// do so, all subject to the following:
+
+// The copyright notices in the Software and this entire statement, including
+// the above license grant, this restriction and the following disclaimer,
+// must be included in all copies of the Software, in whole or in part, and
+// all derivative works of the Software, unless such copies or derivative
+// works are solely in the form of machine-executable object code generated by
+// a source language processor.
+
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+// FITNESS FOR A PARTICULAR PURPOSE, TITLE AND NON-INFRINGEMENT. IN NO EVENT
+// SHALL THE COPYRIGHT HOLDERS OR ANYONE DISTRIBUTING THE SOFTWARE BE LIABLE
+// FOR ANY DAMAGES OR OTHER LIABILITY, WHETHER IN CONTRACT, TORT OR OTHERWISE,
+// ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
+// DEALINGS IN THE SOFTWARE.
+
+// Avoid formatting to keep the changes with the original code minimal.
+// clang-format off
+
+#include <__assert>
+#include <__config>
+#include <charconv>
+
+#include "third_party/libcxx/src/include/ryu/common.h"
+#include "third_party/libcxx/src/include/ryu/d2fixed.h"
+#include "third_party/libcxx/src/include/ryu/d2s.h"
+#include "third_party/libcxx/src/include/ryu/d2s_full_table.h"
+#include "third_party/libcxx/src/include/ryu/d2s_intrinsics.h"
+#include "third_party/libcxx/src/include/ryu/digit_table.h"
+#include "third_party/libcxx/src/include/ryu/ryu.h"
+
+_LIBCPP_BEGIN_NAMESPACE_STD
+
+// We need a 64x128-bit multiplication and a subsequent 128-bit shift.
+// Multiplication:
+//   The 64-bit factor is variable and passed in, the 128-bit factor comes
+//   from a lookup table. We know that the 64-bit factor only has 55
+//   significant bits (i.e., the 9 topmost bits are zeros). The 128-bit
+//   factor only has 124 significant bits (i.e., the 4 topmost bits are
+//   zeros).
+// Shift:
+//   In principle, the multiplication result requires 55 + 124 = 179 bits to
+//   represent. However, we then shift this value to the right by __j, which is
+//   at least __j >= 115, so the result is guaranteed to fit into 179 - 115 = 64
+//   bits. This means that we only need the topmost 64 significant bits of
+//   the 64x128-bit multiplication.
+//
+// There are several ways to do this:
+// 1. Best case: the compiler exposes a 128-bit type.
+//    We perform two 64x64-bit multiplications, add the higher 64 bits of the
+//    lower result to the higher result, and shift by __j - 64 bits.
+//
+//    We explicitly cast from 64-bit to 128-bit, so the compiler can tell
+//    that these are only 64-bit inputs, and can map these to the best
+//    possible sequence of assembly instructions.
+//    x64 machines happen to have matching assembly instructions for
+//    64x64-bit multiplications and 128-bit shifts.
+//
+// 2. Second best case: the compiler exposes intrinsics for the x64 assembly
+//    instructions mentioned in 1.
+//
+// 3. We only have 64x64 bit instructions that return the lower 64 bits of
+//    the result, i.e., we have to use plain C.
+//    Our inputs are less than the full width, so we have three options:
+//    a. Ignore this fact and just implement the intrinsics manually.
+//    b. Split both into 31-bit pieces, which guarantees no internal overflow,
+//       but requires extra work upfront (unless we change the lookup table).
+//    c. Split only the first factor into 31-bit pieces, which also guarantees
+//       no internal overflow, but requires extra work since the intermediate
+//       results are not perfectly aligned.
+#ifdef _LIBCPP_INTRINSIC128
+
+[[nodiscard]] _LIBCPP_HIDE_FROM_ABI inline uint64_t __mulShift(const uint64_t __m, const uint64_t* const __mul, const int32_t __j) {
+  // __m is maximum 55 bits
+  uint64_t __high1;                                               // 128
+  const uint64_t __low1 = __ryu_umul128(__m, __mul[1], &__high1); // 64
+  uint64_t __high0;                                               // 64
+  (void) __ryu_umul128(__m, __mul[0], &__high0);                  // 0
+  const uint64_t __sum = __high0 + __low1;
+  if (__sum < __high0) {
+    ++__high1; // overflow into __high1
+  }
+  return __ryu_shiftright128(__sum, __high1, static_cast<uint32_t>(__j - 64));
+}
+
+[[nodiscard]] _LIBCPP_HIDE_FROM_ABI inline uint64_t __mulShiftAll(const uint64_t __m, const uint64_t* const __mul, const int32_t __j,
+  uint64_t* const __vp, uint64_t* const __vm, const uint32_t __mmShift) {
+  *__vp = __mulShift(4 * __m + 2, __mul, __j);
+  *__vm = __mulShift(4 * __m - 1 - __mmShift, __mul, __j);
+  return __mulShift(4 * __m, __mul, __j);
+}
+
+#else // ^^^ intrinsics available ^^^ / vvv intrinsics unavailable vvv
+
+[[nodiscard]] _LIBCPP_HIDE_FROM_ABI inline _LIBCPP_ALWAYS_INLINE uint64_t __mulShiftAll(uint64_t __m, const uint64_t* const __mul, const int32_t __j,
+  uint64_t* const __vp, uint64_t* const __vm, const uint32_t __mmShift) { // TRANSITION, VSO-634761
+  __m <<= 1;
+  // __m is maximum 55 bits
+  uint64_t __tmp;
+  const uint64_t __lo = __ryu_umul128(__m, __mul[0], &__tmp);
+  uint64_t __hi;
+  const uint64_t __mid = __tmp + __ryu_umul128(__m, __mul[1], &__hi);
+  __hi += __mid < __tmp; // overflow into __hi
+
+  const uint64_t __lo2 = __lo + __mul[0];
+  const uint64_t __mid2 = __mid + __mul[1] + (__lo2 < __lo);
+  const uint64_t __hi2 = __hi + (__mid2 < __mid);
+  *__vp = __ryu_shiftright128(__mid2, __hi2, static_cast<uint32_t>(__j - 64 - 1));
+
+  if (__mmShift == 1) {
+    const uint64_t __lo3 = __lo - __mul[0];
+    const uint64_t __mid3 = __mid - __mul[1] - (__lo3 > __lo);
+    const uint64_t __hi3 = __hi - (__mid3 > __mid);
+    *__vm = __ryu_shiftright128(__mid3, __hi3, static_cast<uint32_t>(__j - 64 - 1));
+  } else {
+    const uint64_t __lo3 = __lo + __lo;
+    const uint64_t __mid3 = __mid + __mid + (__lo3 < __lo);
+    const uint64_t __hi3 = __hi + __hi + (__mid3 < __mid);
+    const uint64_t __lo4 = __lo3 - __mul[0];
+    const uint64_t __mid4 = __mid3 - __mul[1] - (__lo4 > __lo3);
+    const uint64_t __hi4 = __hi3 - (__mid4 > __mid3);
+    *__vm = __ryu_shiftright128(__mid4, __hi4, static_cast<uint32_t>(__j - 64));
+  }
+
+  return __ryu_shiftright128(__mid, __hi, static_cast<uint32_t>(__j - 64 - 1));
+}
+
+#endif // ^^^ intrinsics unavailable ^^^
+
+[[nodiscard]] _LIBCPP_HIDE_FROM_ABI inline uint32_t __decimalLength17(const uint64_t __v) {
+  // This is slightly faster than a loop.
+  // The average output length is 16.38 digits, so we check high-to-low.
+  // Function precondition: __v is not an 18, 19, or 20-digit number.
+  // (17 digits are sufficient for round-tripping.)
+  _LIBCPP_ASSERT(__v < 100000000000000000u, "");
+  if (__v >= 10000000000000000u) { return 17; }
+  if (__v >= 1000000000000000u) { return 16; }
+  if (__v >= 100000000000000u) { return 15; }
+  if (__v >= 10000000000000u) { return 14; }
+  if (__v >= 1000000000000u) { return 13; }
+  if (__v >= 100000000000u) { return 12; }
+  if (__v >= 10000000000u) { return 11; }
+  if (__v >= 1000000000u) { return 10; }
+  if (__v >= 100000000u) { return 9; }
+  if (__v >= 10000000u) { return 8; }
+  if (__v >= 1000000u) { return 7; }
+  if (__v >= 100000u) { return 6; }
+  if (__v >= 10000u) { return 5; }
+  if (__v >= 1000u) { return 4; }
+  if (__v >= 100u) { return 3; }
+  if (__v >= 10u) { return 2; }
+  return 1;
+}
+
+// A floating decimal representing m * 10^e.
+struct __floating_decimal_64 {
+  uint64_t __mantissa;
+  int32_t __exponent;
+};
+
+[[nodiscard]] _LIBCPP_HIDE_FROM_ABI inline __floating_decimal_64 __d2d(const uint64_t __ieeeMantissa, const uint32_t __ieeeExponent) {
+  int32_t __e2;
+  uint64_t __m2;
+  if (__ieeeExponent == 0) {
+    // We subtract 2 so that the bounds computation has 2 additional bits.
+    __e2 = 1 - __DOUBLE_BIAS - __DOUBLE_MANTISSA_BITS - 2;
+    __m2 = __ieeeMantissa;
+  } else {
+    __e2 = static_cast<int32_t>(__ieeeExponent) - __DOUBLE_BIAS - __DOUBLE_MANTISSA_BITS - 2;
+    __m2 = (1ull << __DOUBLE_MANTISSA_BITS) | __ieeeMantissa;
+  }
+  const bool __even = (__m2 & 1) == 0;
+  const bool __acceptBounds = __even;
+
+  // Step 2: Determine the interval of valid decimal representations.
+  const uint64_t __mv = 4 * __m2;
+  // Implicit bool -> int conversion. True is 1, false is 0.
+  const uint32_t __mmShift = __ieeeMantissa != 0 || __ieeeExponent <= 1;
+  // We would compute __mp and __mm like this:
+  // uint64_t __mp = 4 * __m2 + 2;
+  // uint64_t __mm = __mv - 1 - __mmShift;
+
+  // Step 3: Convert to a decimal power base using 128-bit arithmetic.
+  uint64_t __vr, __vp, __vm;
+  int32_t __e10;
+  bool __vmIsTrailingZeros = false;
+  bool __vrIsTrailingZeros = false;
+  if (__e2 >= 0) {
+    // I tried special-casing __q == 0, but there was no effect on performance.
+    // This expression is slightly faster than max(0, __log10Pow2(__e2) - 1).
+    const uint32_t __q = __log10Pow2(__e2) - (__e2 > 3);
+    __e10 = static_cast<int32_t>(__q);
+    const int32_t __k = __DOUBLE_POW5_INV_BITCOUNT + __pow5bits(static_cast<int32_t>(__q)) - 1;
+    const int32_t __i = -__e2 + static_cast<int32_t>(__q) + __k;
+    __vr = __mulShiftAll(__m2, __DOUBLE_POW5_INV_SPLIT[__q], __i, &__vp, &__vm, __mmShift);
+    if (__q <= 21) {
+      // This should use __q <= 22, but I think 21 is also safe. Smaller values
+      // may still be safe, but it's more difficult to reason about them.
+      // Only one of __mp, __mv, and __mm can be a multiple of 5, if any.
+      const uint32_t __mvMod5 = static_cast<uint32_t>(__mv) - 5 * static_cast<uint32_t>(__div5(__mv));
+      if (__mvMod5 == 0) {
+        __vrIsTrailingZeros = __multipleOfPowerOf5(__mv, __q);
+      } else if (__acceptBounds) {
+        // Same as min(__e2 + (~__mm & 1), __pow5Factor(__mm)) >= __q
+        // <=> __e2 + (~__mm & 1) >= __q && __pow5Factor(__mm) >= __q
+        // <=> true && __pow5Factor(__mm) >= __q, since __e2 >= __q.
+        __vmIsTrailingZeros = __multipleOfPowerOf5(__mv - 1 - __mmShift, __q);
+      } else {
+        // Same as min(__e2 + 1, __pow5Factor(__mp)) >= __q.
+        __vp -= __multipleOfPowerOf5(__mv + 2, __q);
+      }
+    }
+  } else {
+    // This expression is slightly faster than max(0, __log10Pow5(-__e2) - 1).
+    const uint32_t __q = __log10Pow5(-__e2) - (-__e2 > 1);
+    __e10 = static_cast<int32_t>(__q) + __e2;
+    const int32_t __i = -__e2 - static_cast<int32_t>(__q);
+    const int32_t __k = __pow5bits(__i) - __DOUBLE_POW5_BITCOUNT;
+    const int32_t __j = static_cast<int32_t>(__q) - __k;
+    __vr = __mulShiftAll(__m2, __DOUBLE_POW5_SPLIT[__i], __j, &__vp, &__vm, __mmShift);
+    if (__q <= 1) {
+      // {__vr,__vp,__vm} is trailing zeros if {__mv,__mp,__mm} has at least __q trailing 0 bits.
+      // __mv = 4 * __m2, so it always has at least two trailing 0 bits.
+      __vrIsTrailingZeros = true;
+      if (__acceptBounds) {
+        // __mm = __mv - 1 - __mmShift, so it has 1 trailing 0 bit iff __mmShift == 1.
+        __vmIsTrailingZeros = __mmShift == 1;
+      } else {
+        // __mp = __mv + 2, so it always has at least one trailing 0 bit.
+        --__vp;
+      }
+    } else if (__q < 63) { // TRANSITION(ulfjack): Use a tighter bound here.
+      // We need to compute min(ntz(__mv), __pow5Factor(__mv) - __e2) >= __q - 1
+      // <=> ntz(__mv) >= __q - 1 && __pow5Factor(__mv) - __e2 >= __q - 1
+      // <=> ntz(__mv) >= __q - 1 (__e2 is negative and -__e2 >= __q)
+      // <=> (__mv & ((1 << (__q - 1)) - 1)) == 0
+      // We also need to make sure that the left shift does not overflow.
+      __vrIsTrailingZeros = __multipleOfPowerOf2(__mv, __q - 1);
+    }
+  }
+
+  // Step 4: Find the shortest decimal representation in the interval of valid representations.
+  int32_t __removed = 0;
+  uint8_t __lastRemovedDigit = 0;
+  uint64_t _Output;
+  // On average, we remove ~2 digits.
+  if (__vmIsTrailingZeros || __vrIsTrailingZeros) {
+    // General case, which happens rarely (~0.7%).
+    for (;;) {
+      const uint64_t __vpDiv10 = __div10(__vp);
+      const uint64_t __vmDiv10 = __div10(__vm);
+      if (__vpDiv10 <= __vmDiv10) {
+        break;
+      }
+      const uint32_t __vmMod10 = static_cast<uint32_t>(__vm) - 10 * static_cast<uint32_t>(__vmDiv10);
+      const uint64_t __vrDiv10 = __div10(__vr);
+      const uint32_t __vrMod10 = static_cast<uint32_t>(__vr) - 10 * static_cast<uint32_t>(__vrDiv10);
+      __vmIsTrailingZeros &= __vmMod10 == 0;
+      __vrIsTrailingZeros &= __lastRemovedDigit == 0;
+      __lastRemovedDigit = static_cast<uint8_t>(__vrMod10);
+      __vr = __vrDiv10;
+      __vp = __vpDiv10;
+      __vm = __vmDiv10;
+      ++__removed;
+    }
+    if (__vmIsTrailingZeros) {
+      for (;;) {
+        const uint64_t __vmDiv10 = __div10(__vm);
+        const uint32_t __vmMod10 = static_cast<uint32_t>(__vm) - 10 * static_cast<uint32_t>(__vmDiv10);
+        if (__vmMod10 != 0) {
+          break;
+        }
+        const uint64_t __vpDiv10 = __div10(__vp);
+        const uint64_t __vrDiv10 = __div10(__vr);
+        const uint32_t __vrMod10 = static_cast<uint32_t>(__vr) - 10 * static_cast<uint32_t>(__vrDiv10);
+        __vrIsTrailingZeros &= __lastRemovedDigit == 0;
+        __lastRemovedDigit = static_cast<uint8_t>(__vrMod10);
+        __vr = __vrDiv10;
+        __vp = __vpDiv10;
+        __vm = __vmDiv10;
+        ++__removed;
+      }
+    }
+    if (__vrIsTrailingZeros && __lastRemovedDigit == 5 && __vr % 2 == 0) {
+      // Round even if the exact number is .....50..0.
+      __lastRemovedDigit = 4;
+    }
+    // We need to take __vr + 1 if __vr is outside bounds or we need to round up.
+    _Output = __vr + ((__vr == __vm && (!__acceptBounds || !__vmIsTrailingZeros)) || __lastRemovedDigit >= 5);
+  } else {
+    // Specialized for the common case (~99.3%). Percentages below are relative to this.
+    bool __roundUp = false;
+    const uint64_t __vpDiv100 = __div100(__vp);
+    const uint64_t __vmDiv100 = __div100(__vm);
+    if (__vpDiv100 > __vmDiv100) { // Optimization: remove two digits at a time (~86.2%).
+      const uint64_t __vrDiv100 = __div100(__vr);
+      const uint32_t __vrMod100 = static_cast<uint32_t>(__vr) - 100 * static_cast<uint32_t>(__vrDiv100);
+      __roundUp = __vrMod100 >= 50;
+      __vr = __vrDiv100;
+      __vp = __vpDiv100;
+      __vm = __vmDiv100;
+      __removed += 2;
+    }
+    // Loop iterations below (approximately), without optimization above:
+    // 0: 0.03%, 1: 13.8%, 2: 70.6%, 3: 14.0%, 4: 1.40%, 5: 0.14%, 6+: 0.02%
+    // Loop iterations below (approximately), with optimization above:
+    // 0: 70.6%, 1: 27.8%, 2: 1.40%, 3: 0.14%, 4+: 0.02%
+    for (;;) {
+      const uint64_t __vpDiv10 = __div10(__vp);
+      const uint64_t __vmDiv10 = __div10(__vm);
+      if (__vpDiv10 <= __vmDiv10) {
+        break;
+      }
+      const uint64_t __vrDiv10 = __div10(__vr);
+      const uint32_t __vrMod10 = static_cast<uint32_t>(__vr) - 10 * static_cast<uint32_t>(__vrDiv10);
+      __roundUp = __vrMod10 >= 5;
+      __vr = __vrDiv10;
+      __vp = __vpDiv10;
+      __vm = __vmDiv10;
+      ++__removed;
+    }
+    // We need to take __vr + 1 if __vr is outside bounds or we need to round up.
+    _Output = __vr + (__vr == __vm || __roundUp);
+  }
+  const int32_t __exp = __e10 + __removed;
+
+  __floating_decimal_64 __fd;
+  __fd.__exponent = __exp;
+  __fd.__mantissa = _Output;
+  return __fd;
+}
+
+[[nodiscard]] _LIBCPP_HIDE_FROM_ABI inline to_chars_result __to_chars(char* const _First, char* const _Last, const __floating_decimal_64 __v,
+  chars_format _Fmt, const double __f) {
+  // Step 5: Print the decimal representation.
+  uint64_t _Output = __v.__mantissa;
+  int32_t _Ryu_exponent = __v.__exponent;
+  const uint32_t __olength = __decimalLength17(_Output);
+  int32_t _Scientific_exponent = _Ryu_exponent + static_cast<int32_t>(__olength) - 1;
+
+  if (_Fmt == chars_format{}) {
+    int32_t _Lower;
+    int32_t _Upper;
+
+    if (__olength == 1) {
+      // Value | Fixed   | Scientific
+      // 1e-3  | "0.001" | "1e-03"
+      // 1e4   | "10000" | "1e+04"
+      _Lower = -3;
+      _Upper = 4;
+    } else {
+      // Value   | Fixed       | Scientific
+      // 1234e-7 | "0.0001234" | "1.234e-04"
+      // 1234e5  | "123400000" | "1.234e+08"
+      _Lower = -static_cast<int32_t>(__olength + 3);
+      _Upper = 5;
+    }
+
+    if (_Lower <= _Ryu_exponent && _Ryu_exponent <= _Upper) {
+      _Fmt = chars_format::fixed;
+    } else {
+      _Fmt = chars_format::scientific;
+    }
+  } else if (_Fmt == chars_format::general) {
+    // C11 7.21.6.1 "The fprintf function"/8:
+    // "Let P equal [...] 6 if the precision is omitted [...].
+    // Then, if a conversion with style E would have an exponent of X:
+    // - if P > X >= -4, the conversion is with style f [...].
+    // - otherwise, the conversion is with style e [...]."
+    if (-4 <= _Scientific_exponent && _Scientific_exponent < 6) {
+      _Fmt = chars_format::fixed;
+    } else {
+      _Fmt = chars_format::scientific;
+    }
+  }
+
+  if (_Fmt == chars_format::fixed) {
+    // Example: _Output == 1729, __olength == 4
+
+    // _Ryu_exponent | Printed  | _Whole_digits | _Total_fixed_length  | Notes
+    // --------------|----------|---------------|----------------------|---------------------------------------
+    //             2 | 172900   |  6            | _Whole_digits        | Ryu can't be used for printing
+    //             1 | 17290    |  5            | (sometimes adjusted) | when the trimmed digits are nonzero.
+    // --------------|----------|---------------|----------------------|---------------------------------------
+    //             0 | 1729     |  4            | _Whole_digits        | Unified length cases.
+    // --------------|----------|---------------|----------------------|---------------------------------------
+    //            -1 | 172.9    |  3            | __olength + 1        | This case can't happen for
+    //            -2 | 17.29    |  2            |                      | __olength == 1, but no additional
+    //            -3 | 1.729    |  1            |                      | code is needed to avoid it.
+    // --------------|----------|---------------|----------------------|---------------------------------------
+    //            -4 | 0.1729   |  0            | 2 - _Ryu_exponent    | C11 7.21.6.1 "The fprintf function"/8:
+    //            -5 | 0.01729  | -1            |                      | "If a decimal-point character appears,
+    //            -6 | 0.001729 | -2            |                      | at least one digit appears before it."
+
+    const int32_t _Whole_digits = static_cast<int32_t>(__olength) + _Ryu_exponent;
+
+    uint32_t _Total_fixed_length;
+    if (_Ryu_exponent >= 0) { // cases "172900" and "1729"
+      _Total_fixed_length = static_cast<uint32_t>(_Whole_digits);
+      if (_Output == 1) {
+        // Rounding can affect the number of digits.
+        // For example, 1e23 is exactly "99999999999999991611392" which is 23 digits instead of 24.
+        // We can use a lookup table to detect this and adjust the total length.
+        static constexpr uint8_t _Adjustment[309] = {
+          0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,1,1,0,0,0,1,1,0,1,0,1,1,1,0,1,1,1,0,0,0,0,0,
+          1,1,0,0,1,0,1,1,1,0,0,0,0,1,1,1,1,0,0,0,1,1,1,1,0,0,0,1,1,1,1,0,1,0,1,0,1,1,0,0,0,0,1,1,1,
+          1,0,0,0,0,0,0,0,1,1,0,1,1,0,0,1,0,1,0,1,0,1,1,0,0,0,0,0,1,1,1,0,0,1,1,1,1,1,0,1,0,1,1,0,1,
+          1,0,0,0,0,0,0,0,0,0,1,1,1,0,0,1,0,0,1,0,0,1,1,1,1,0,0,1,1,0,1,1,0,1,1,0,1,0,0,0,1,0,0,0,1,
+          0,1,0,1,0,1,1,1,0,0,0,0,0,0,1,1,1,1,0,0,1,0,1,1,1,0,0,0,1,0,1,1,1,1,1,1,0,1,0,1,1,0,0,0,1,
+          1,1,0,1,1,0,0,0,1,0,0,0,1,0,1,0,0,0,0,0,0,0,1,0,1,1,0,0,1,1,1,0,0,0,1,0,1,0,0,0,0,0,1,1,0,
+          0,1,0,1,1,1,0,0,1,0,0,0,0,1,0,1,0,0,0,0,0,1,0,1,0,1,1,0,1,0,0,0,0,0,1,1,0,1,0 };
+        _Total_fixed_length -= _Adjustment[_Ryu_exponent];
+        // _Whole_digits doesn't need to be adjusted because these cases won't refer to it later.
+      }
+    } else if (_Whole_digits > 0) { // case "17.29"
+      _Total_fixed_length = __olength + 1;
+    } else { // case "0.001729"
+      _Total_fixed_length = static_cast<uint32_t>(2 - _Ryu_exponent);
+    }
+
+    if (_Last - _First < static_cast<ptrdiff_t>(_Total_fixed_length)) {
+      return { _Last, errc::value_too_large };
+    }
+
+    char* _Mid;
+    if (_Ryu_exponent > 0) { // case "172900"
+      bool _Can_use_ryu;
+
+      if (_Ryu_exponent > 22) { // 10^22 is the largest power of 10 that's exactly representable as a double.
+        _Can_use_ryu = false;
+      } else {
+        // Ryu generated X: __v.__mantissa * 10^_Ryu_exponent
+        // __v.__mantissa == 2^_Trailing_zero_bits * (__v.__mantissa >> _Trailing_zero_bits)
+        // 10^_Ryu_exponent == 2^_Ryu_exponent * 5^_Ryu_exponent
+
+        // _Trailing_zero_bits is [0, 56] (aside: because 2^56 is the largest power of 2
+        // with 17 decimal digits, which is double's round-trip limit.)
+        // _Ryu_exponent is [1, 22].
+        // Normalization adds [2, 52] (aside: at least 2 because the pre-normalized mantissa is at least 5).
+        // This adds up to [3, 130], which is well below double's maximum binary exponent 1023.
+
+        // Therefore, we just need to consider (__v.__mantissa >> _Trailing_zero_bits) * 5^_Ryu_exponent.
+
+        // If that product would exceed 53 bits, then X can't be exactly represented as a double.
+        // (That's not a problem for round-tripping, because X is close enough to the original double,
+        // but X isn't mathematically equal to the original double.) This requires a high-precision fallback.
+
+        // If the product is 53 bits or smaller, then X can be exactly represented as a double (and we don't
+        // need to re-synthesize it; the original double must have been X, because Ryu wouldn't produce the
+        // same output for two different doubles X and Y). This allows Ryu's output to be used (zero-filled).
+
+        // (2^53 - 1) / 5^0 (for indexing), (2^53 - 1) / 5^1, ..., (2^53 - 1) / 5^22
+        static constexpr uint64_t _Max_shifted_mantissa[23] = {
+          9007199254740991u, 1801439850948198u, 360287970189639u, 72057594037927u, 14411518807585u,
+          2882303761517u, 576460752303u, 115292150460u, 23058430092u, 4611686018u, 922337203u, 184467440u,
+          36893488u, 7378697u, 1475739u, 295147u, 59029u, 11805u, 2361u, 472u, 94u, 18u, 3u };
+
+        unsigned long _Trailing_zero_bits = 0;
+#ifdef _LIBCPP_HAS_BITSCAN64
+        (void) _BitScanForward64(&_Trailing_zero_bits, __v.__mantissa); // __v.__mantissa is guaranteed nonzero
+#else // ^^^ 64-bit ^^^ / vvv 32-bit vvv
+        const uint32_t _Low_mantissa = static_cast<uint32_t>(__v.__mantissa);
+        if (_Low_mantissa != 0) {
+          (void) _BitScanForward(&_Trailing_zero_bits, _Low_mantissa);
+        } else {
+          const uint32_t _High_mantissa = static_cast<uint32_t>(__v.__mantissa >> 32); // nonzero here
+          (void) _BitScanForward(&_Trailing_zero_bits, _High_mantissa);
+          _Trailing_zero_bits += 32;
+        }
+#endif // ^^^ 32-bit ^^^
+        const uint64_t _Shifted_mantissa = __v.__mantissa >> _Trailing_zero_bits;
+        _Can_use_ryu = _Shifted_mantissa <= _Max_shifted_mantissa[_Ryu_exponent];
+      }
+
+      if (!_Can_use_ryu) {
+        // Print the integer exactly.
+        // Performance note: This will redundantly perform bounds checking.
+        // Performance note: This will redundantly decompose the IEEE representation.
+        return __d2fixed_buffered_n(_First, _Last, __f, 0);
+      }
+
+      // _Can_use_ryu
+      // Print the decimal digits, left-aligned within [_First, _First + _Total_fixed_length).
+      _Mid = _First + __olength;
+    } else { // cases "1729", "17.29", and "0.001729"
+      // Print the decimal digits, right-aligned within [_First, _First + _Total_fixed_length).
+      _Mid = _First + _Total_fixed_length;
+    }
+
+    // We prefer 32-bit operations, even on 64-bit platforms.
+    // We have at most 17 digits, and uint32_t can store 9 digits.
+    // If _Output doesn't fit into uint32_t, we cut off 8 digits,
+    // so the rest will fit into uint32_t.
+    if ((_Output >> 32) != 0) {
+      // Expensive 64-bit division.
+      const uint64_t __q = __div1e8(_Output);
+      uint32_t __output2 = static_cast<uint32_t>(_Output - 100000000 * __q);
+      _Output = __q;
+
+      const uint32_t __c = __output2 % 10000;
+      __output2 /= 10000;
+      const uint32_t __d = __output2 % 10000;
+      const uint32_t __c0 = (__c % 100) << 1;
+      const uint32_t __c1 = (__c / 100) << 1;
+      const uint32_t __d0 = (__d % 100) << 1;
+      const uint32_t __d1 = (__d / 100) << 1;
+
+      std::memcpy(_Mid -= 2, __DIGIT_TABLE + __c0, 2);
+      std::memcpy(_Mid -= 2, __DIGIT_TABLE + __c1, 2);
+      std::memcpy(_Mid -= 2, __DIGIT_TABLE + __d0, 2);
+      std::memcpy(_Mid -= 2, __DIGIT_TABLE + __d1, 2);
+    }
+    uint32_t __output2 = static_cast<uint32_t>(_Output);
+    while (__output2 >= 10000) {
+#ifdef __clang__ // TRANSITION, LLVM-38217
+      const uint32_t __c = __output2 - 10000 * (__output2 / 10000);
+#else
+      const uint32_t __c = __output2 % 10000;
+#endif
+      __output2 /= 10000;
+      const uint32_t __c0 = (__c % 100) << 1;
+      const uint32_t __c1 = (__c / 100) << 1;
+      std::memcpy(_Mid -= 2, __DIGIT_TABLE + __c0, 2);
+      std::memcpy(_Mid -= 2, __DIGIT_TABLE + __c1, 2);
+    }
+    if (__output2 >= 100) {
+      const uint32_t __c = (__output2 % 100) << 1;
+      __output2 /= 100;
+      std::memcpy(_Mid -= 2, __DIGIT_TABLE + __c, 2);
+    }
+    if (__output2 >= 10) {
+      const uint32_t __c = __output2 << 1;
+      std::memcpy(_Mid -= 2, __DIGIT_TABLE + __c, 2);
+    } else {
+      *--_Mid = static_cast<char>('0' + __output2);
+    }
+
+    if (_Ryu_exponent > 0) { // case "172900" with _Can_use_ryu
+      // Performance note: it might be more efficient to do this immediately after setting _Mid.
+      std::memset(_First + __olength, '0', static_cast<size_t>(_Ryu_exponent));
+    } else if (_Ryu_exponent == 0) { // case "1729"
+      // Done!
+    } else if (_Whole_digits > 0) { // case "17.29"
+      // Performance note: moving digits might not be optimal.
+      std::memmove(_First, _First + 1, static_cast<size_t>(_Whole_digits));
+      _First[_Whole_digits] = '.';
+    } else { // case "0.001729"
+      // Performance note: a larger memset() followed by overwriting '.' might be more efficient.
+      _First[0] = '0';
+      _First[1] = '.';
+      std::memset(_First + 2, '0', static_cast<size_t>(-_Whole_digits));
+    }
+
+    return { _First + _Total_fixed_length, errc{} };
+  }
+
+  const uint32_t _Total_scientific_length = __olength + (__olength > 1) // digits + possible decimal point
+    + (-100 < _Scientific_exponent && _Scientific_exponent < 100 ? 4 : 5); // + scientific exponent
+  if (_Last - _First < static_cast<ptrdiff_t>(_Total_scientific_length)) {
+    return { _Last, errc::value_too_large };
+  }
+  char* const __result = _First;
+
+  // Print the decimal digits.
+  uint32_t __i = 0;
+  // We prefer 32-bit operations, even on 64-bit platforms.
+  // We have at most 17 digits, and uint32_t can store 9 digits.
+  // If _Output doesn't fit into uint32_t, we cut off 8 digits,
+  // so the rest will fit into uint32_t.
+  if ((_Output >> 32) != 0) {
+    // Expensive 64-bit division.
+    const uint64_t __q = __div1e8(_Output);
+    uint32_t __output2 = static_cast<uint32_t>(_Output) - 100000000 * static_cast<uint32_t>(__q);
+    _Output = __q;
+
+    const uint32_t __c = __output2 % 10000;
+    __output2 /= 10000;
+    const uint32_t __d = __output2 % 10000;
+    const uint32_t __c0 = (__c % 100) << 1;
+    const uint32_t __c1 = (__c / 100) << 1;
+    const uint32_t __d0 = (__d % 100) << 1;
+    const uint32_t __d1 = (__d / 100) << 1;
+    std::memcpy(__result + __olength - __i - 1, __DIGIT_TABLE + __c0, 2);
+    std::memcpy(__result + __olength - __i - 3, __DIGIT_TABLE + __c1, 2);
+    std::memcpy(__result + __olength - __i - 5, __DIGIT_TABLE + __d0, 2);
+    std::memcpy(__result + __olength - __i - 7, __DIGIT_TABLE + __d1, 2);
+    __i += 8;
+  }
+  uint32_t __output2 = static_cast<uint32_t>(_Output);
+  while (__output2 >= 10000) {
+#ifdef __clang__ // TRANSITION, LLVM-38217
+    const uint32_t __c = __output2 - 10000 * (__output2 / 10000);
+#else
+    const uint32_t __c = __output2 % 10000;
+#endif
+    __output2 /= 10000;
+    const uint32_t __c0 = (__c % 100) << 1;
+    const uint32_t __c1 = (__c / 100) << 1;
+    std::memcpy(__result + __olength - __i - 1, __DIGIT_TABLE + __c0, 2);
+    std::memcpy(__result + __olength - __i - 3, __DIGIT_TABLE + __c1, 2);
+    __i += 4;
+  }
+  if (__output2 >= 100) {
+    const uint32_t __c = (__output2 % 100) << 1;
+    __output2 /= 100;
+    std::memcpy(__result + __olength - __i - 1, __DIGIT_TABLE + __c, 2);
+    __i += 2;
+  }
+  if (__output2 >= 10) {
+    const uint32_t __c = __output2 << 1;
+    // We can't use memcpy here: the decimal dot goes between these two digits.
+    __result[2] = __DIGIT_TABLE[__c + 1];
+    __result[0] = __DIGIT_TABLE[__c];
+  } else {
+    __result[0] = static_cast<char>('0' + __output2);
+  }
+
+  // Print decimal point if needed.
+  uint32_t __index;
+  if (__olength > 1) {
+    __result[1] = '.';
+    __index = __olength + 1;
+  } else {
+    __index = 1;
+  }
+
+  // Print the exponent.
+  __result[__index++] = 'e';
+  if (_Scientific_exponent < 0) {
+    __result[__index++] = '-';
+    _Scientific_exponent = -_Scientific_exponent;
+  } else {
+    __result[__index++] = '+';
+  }
+
+  if (_Scientific_exponent >= 100) {
+    const int32_t __c = _Scientific_exponent % 10;
+    std::memcpy(__result + __index, __DIGIT_TABLE + 2 * (_Scientific_exponent / 10), 2);
+    __result[__index + 2] = static_cast<char>('0' + __c);
+    __index += 3;
+  } else {
+    std::memcpy(__result + __index, __DIGIT_TABLE + 2 * _Scientific_exponent, 2);
+    __index += 2;
+  }
+
+  return { _First + _Total_scientific_length, errc{} };
+}
+
+[[nodiscard]] _LIBCPP_HIDE_FROM_ABI inline bool __d2d_small_int(const uint64_t __ieeeMantissa, const uint32_t __ieeeExponent,
+  __floating_decimal_64* const __v) {
+  const uint64_t __m2 = (1ull << __DOUBLE_MANTISSA_BITS) | __ieeeMantissa;
+  const int32_t __e2 = static_cast<int32_t>(__ieeeExponent) - __DOUBLE_BIAS - __DOUBLE_MANTISSA_BITS;
+
+  if (__e2 > 0) {
+    // f = __m2 * 2^__e2 >= 2^53 is an integer.
+    // Ignore this case for now.
+    return false;
+  }
+
+  if (__e2 < -52) {
+    // f < 1.
+    return false;
+  }
+
+  // Since 2^52 <= __m2 < 2^53 and 0 <= -__e2 <= 52: 1 <= f = __m2 / 2^-__e2 < 2^53.
+  // Test if the lower -__e2 bits of the significand are 0, i.e. whether the fraction is 0.
+  const uint64_t __mask = (1ull << -__e2) - 1;
+  const uint64_t __fraction = __m2 & __mask;
+  if (__fraction != 0) {
+    return false;
+  }
+
+  // f is an integer in the range [1, 2^53).
+  // Note: __mantissa might contain trailing (decimal) 0's.
+  // Note: since 2^53 < 10^16, there is no need to adjust __decimalLength17().
+  __v->__mantissa = __m2 >> -__e2;
+  __v->__exponent = 0;
+  return true;
+}
+
+[[nodiscard]] to_chars_result __d2s_buffered_n(char* const _First, char* const _Last, const double __f,
+  const chars_format _Fmt) {
+
+  // Step 1: Decode the floating-point number, and unify normalized and subnormal cases.
+  const uint64_t __bits = __double_to_bits(__f);
+
+  // Case distinction; exit early for the easy cases.
+  if (__bits == 0) {
+    if (_Fmt == chars_format::scientific) {
+      if (_Last - _First < 5) {
+        return { _Last, errc::value_too_large };
+      }
+
+      std::memcpy(_First, "0e+00", 5);
+
+      return { _First + 5, errc{} };
+    }
+
+    // Print "0" for chars_format::fixed, chars_format::general, and chars_format{}.
+    if (_First == _Last) {
+      return { _Last, errc::value_too_large };
+    }
+
+    *_First = '0';
+
+    return { _First + 1, errc{} };
+  }
+
+  // Decode __bits into mantissa and exponent.
+  const uint64_t __ieeeMantissa = __bits & ((1ull << __DOUBLE_MANTISSA_BITS) - 1);
+  const uint32_t __ieeeExponent = static_cast<uint32_t>(__bits >> __DOUBLE_MANTISSA_BITS);
+
+  if (_Fmt == chars_format::fixed) {
+    // const uint64_t _Mantissa2 = __ieeeMantissa | (1ull << __DOUBLE_MANTISSA_BITS); // restore implicit bit
+    const int32_t _Exponent2 = static_cast<int32_t>(__ieeeExponent)
+      - __DOUBLE_BIAS - __DOUBLE_MANTISSA_BITS; // bias and normalization
+
+    // Normal values are equal to _Mantissa2 * 2^_Exponent2.
+    // (Subnormals are different, but they'll be rejected by the _Exponent2 test here, so they can be ignored.)
+
+    // For nonzero integers, _Exponent2 >= -52. (The minimum value occurs when _Mantissa2 * 2^_Exponent2 is 1.
+    // In that case, _Mantissa2 is the implicit 1 bit followed by 52 zeros, so _Exponent2 is -52 to shift away
+    // the zeros.) The dense range of exactly representable integers has negative or zero exponents
+    // (as positive exponents make the range non-dense). For that dense range, Ryu will always be used:
+    // every digit is necessary to uniquely identify the value, so Ryu must print them all.
+
+    // Positive exponents are the non-dense range of exactly representable integers. This contains all of the values
+    // for which Ryu can't be used (and a few Ryu-friendly values). We can save time by detecting positive
+    // exponents here and skipping Ryu. Calling __d2fixed_buffered_n() with precision 0 is valid for all integers
+    // (so it's okay if we call it with a Ryu-friendly value).
+    if (_Exponent2 > 0) {
+      return __d2fixed_buffered_n(_First, _Last, __f, 0);
+    }
+  }
+
+  __floating_decimal_64 __v;
+  const bool __isSmallInt = __d2d_small_int(__ieeeMantissa, __ieeeExponent, &__v);
+  if (__isSmallInt) {
+    // For small integers in the range [1, 2^53), __v.__mantissa might contain trailing (decimal) zeros.
+    // For scientific notation we need to move these zeros into the exponent.
+    // (This is not needed for fixed-point notation, so it might be beneficial to trim
+    // trailing zeros in __to_chars only if needed - once fixed-point notation output is implemented.)
+    for (;;) {
+      const uint64_t __q = __div10(__v.__mantissa);
+      const uint32_t __r = static_cast<uint32_t>(__v.__mantissa) - 10 * static_cast<uint32_t>(__q);
+      if (__r != 0) {
+        break;
+      }
+      __v.__mantissa = __q;
+      ++__v.__exponent;
+    }
+  } else {
+    __v = __d2d(__ieeeMantissa, __ieeeExponent);
+  }
+
+  return __to_chars(_First, _Last, __v, _Fmt, __f);
+}
+
+_LIBCPP_END_NAMESPACE_STD
+
+// clang-format on

third_party/libcxx/src/ryu/f2s.cpp

@@ -0,0 +1,716 @@
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+// Copyright (c) Microsoft Corporation.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+
+// Copyright 2018 Ulf Adams
+// Copyright (c) Microsoft Corporation. All rights reserved.
+
+// Boost Software License - Version 1.0 - August 17th, 2003
+
+// Permission is hereby granted, free of charge, to any person or organization
+// obtaining a copy of the software and accompanying documentation covered by
+// this license (the "Software") to use, reproduce, display, distribute,
+// execute, and transmit the Software, and to prepare derivative works of the
+// Software, and to permit third-parties to whom the Software is furnished to
+// do so, all subject to the following:
+
+// The copyright notices in the Software and this entire statement, including
+// the above license grant, this restriction and the following disclaimer,
+// must be included in all copies of the Software, in whole or in part, and
+// all derivative works of the Software, unless such copies or derivative
+// works are solely in the form of machine-executable object code generated by
+// a source language processor.
+
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+// FITNESS FOR A PARTICULAR PURPOSE, TITLE AND NON-INFRINGEMENT. IN NO EVENT
+// SHALL THE COPYRIGHT HOLDERS OR ANYONE DISTRIBUTING THE SOFTWARE BE LIABLE
+// FOR ANY DAMAGES OR OTHER LIABILITY, WHETHER IN CONTRACT, TORT OR OTHERWISE,
+// ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
+// DEALINGS IN THE SOFTWARE.
+
+// Avoid formatting to keep the changes with the original code minimal.
+// clang-format off
+
+#include <__assert>
+#include <__config>
+#include <charconv>
+
+#include "third_party/libcxx/src/include/ryu/common.h"
+#include "third_party/libcxx/src/include/ryu/d2fixed.h"
+#include "third_party/libcxx/src/include/ryu/d2s_intrinsics.h"
+#include "third_party/libcxx/src/include/ryu/digit_table.h"
+#include "third_party/libcxx/src/include/ryu/f2s.h"
+#include "third_party/libcxx/src/include/ryu/ryu.h"
+
+_LIBCPP_BEGIN_NAMESPACE_STD
+
+inline constexpr int __FLOAT_MANTISSA_BITS = 23;
+inline constexpr int __FLOAT_EXPONENT_BITS = 8;
+inline constexpr int __FLOAT_BIAS = 127;
+
+inline constexpr int __FLOAT_POW5_INV_BITCOUNT = 59;
+inline constexpr uint64_t __FLOAT_POW5_INV_SPLIT[31] = {
+  576460752303423489u, 461168601842738791u, 368934881474191033u, 295147905179352826u,
+  472236648286964522u, 377789318629571618u, 302231454903657294u, 483570327845851670u,
+  386856262276681336u, 309485009821345069u, 495176015714152110u, 396140812571321688u,
+  316912650057057351u, 507060240091291761u, 405648192073033409u, 324518553658426727u,
+  519229685853482763u, 415383748682786211u, 332306998946228969u, 531691198313966350u,
+  425352958651173080u, 340282366920938464u, 544451787073501542u, 435561429658801234u,
+  348449143727040987u, 557518629963265579u, 446014903970612463u, 356811923176489971u,
+  570899077082383953u, 456719261665907162u, 365375409332725730u
+};
+inline constexpr int __FLOAT_POW5_BITCOUNT = 61;
+inline constexpr uint64_t __FLOAT_POW5_SPLIT[47] = {
+  1152921504606846976u, 1441151880758558720u, 1801439850948198400u, 2251799813685248000u,
+  1407374883553280000u, 1759218604441600000u, 2199023255552000000u, 1374389534720000000u,
+  1717986918400000000u, 2147483648000000000u, 1342177280000000000u, 1677721600000000000u,
+  2097152000000000000u, 1310720000000000000u, 1638400000000000000u, 2048000000000000000u,
+  1280000000000000000u, 1600000000000000000u, 2000000000000000000u, 1250000000000000000u,
+  1562500000000000000u, 1953125000000000000u, 1220703125000000000u, 1525878906250000000u,
+  1907348632812500000u, 1192092895507812500u, 1490116119384765625u, 1862645149230957031u,
+  1164153218269348144u, 1455191522836685180u, 1818989403545856475u, 2273736754432320594u,
+  1421085471520200371u, 1776356839400250464u, 2220446049250313080u, 1387778780781445675u,
+  1734723475976807094u, 2168404344971008868u, 1355252715606880542u, 1694065894508600678u,
+  2117582368135750847u, 1323488980084844279u, 1654361225106055349u, 2067951531382569187u,
+  1292469707114105741u, 1615587133892632177u, 2019483917365790221u
+};
+
+[[nodiscard]] _LIBCPP_HIDE_FROM_ABI inline uint32_t __pow5Factor(uint32_t __value) {
+  uint32_t __count = 0;
+  for (;;) {
+    _LIBCPP_ASSERT(__value != 0, "");
+    const uint32_t __q = __value / 5;
+    const uint32_t __r = __value % 5;
+    if (__r != 0) {
+      break;
+    }
+    __value = __q;
+    ++__count;
+  }
+  return __count;
+}
+
+// Returns true if __value is divisible by 5^__p.
+[[nodiscard]] _LIBCPP_HIDE_FROM_ABI inline bool __multipleOfPowerOf5(const uint32_t __value, const uint32_t __p) {
+  return __pow5Factor(__value) >= __p;
+}
+
+// Returns true if __value is divisible by 2^__p.
+[[nodiscard]] _LIBCPP_HIDE_FROM_ABI inline bool __multipleOfPowerOf2(const uint32_t __value, const uint32_t __p) {
+  _LIBCPP_ASSERT(__value != 0, "");
+  _LIBCPP_ASSERT(__p < 32, "");
+  // __builtin_ctz doesn't appear to be faster here.
+  return (__value & ((1u << __p) - 1)) == 0;
+}
+
+[[nodiscard]] _LIBCPP_HIDE_FROM_ABI inline uint32_t __mulShift(const uint32_t __m, const uint64_t __factor, const int32_t __shift) {
+  _LIBCPP_ASSERT(__shift > 32, "");
+
+  // The casts here help MSVC to avoid calls to the __allmul library
+  // function.
+  const uint32_t __factorLo = static_cast<uint32_t>(__factor);
+  const uint32_t __factorHi = static_cast<uint32_t>(__factor >> 32);
+  const uint64_t __bits0 = static_cast<uint64_t>(__m) * __factorLo;
+  const uint64_t __bits1 = static_cast<uint64_t>(__m) * __factorHi;
+
+#ifndef _LIBCPP_64_BIT
+  // On 32-bit platforms we can avoid a 64-bit shift-right since we only
+  // need the upper 32 bits of the result and the shift value is > 32.
+  const uint32_t __bits0Hi = static_cast<uint32_t>(__bits0 >> 32);
+  uint32_t __bits1Lo = static_cast<uint32_t>(__bits1);
+  uint32_t __bits1Hi = static_cast<uint32_t>(__bits1 >> 32);
+  __bits1Lo += __bits0Hi;
+  __bits1Hi += (__bits1Lo < __bits0Hi);
+  const int32_t __s = __shift - 32;
+  return (__bits1Hi << (32 - __s)) | (__bits1Lo >> __s);
+#else // ^^^ 32-bit ^^^ / vvv 64-bit vvv
+  const uint64_t __sum = (__bits0 >> 32) + __bits1;
+  const uint64_t __shiftedSum = __sum >> (__shift - 32);
+  _LIBCPP_ASSERT(__shiftedSum <= UINT32_MAX, "");
+  return static_cast<uint32_t>(__shiftedSum);
+#endif // ^^^ 64-bit ^^^
+}
+
+[[nodiscard]] _LIBCPP_HIDE_FROM_ABI inline uint32_t __mulPow5InvDivPow2(const uint32_t __m, const uint32_t __q, const int32_t __j) {
+  return __mulShift(__m, __FLOAT_POW5_INV_SPLIT[__q], __j);
+}
+
+[[nodiscard]] _LIBCPP_HIDE_FROM_ABI inline uint32_t __mulPow5divPow2(const uint32_t __m, const uint32_t __i, const int32_t __j) {
+  return __mulShift(__m, __FLOAT_POW5_SPLIT[__i], __j);
+}
+
+// A floating decimal representing m * 10^e.
+struct __floating_decimal_32 {
+  uint32_t __mantissa;
+  int32_t __exponent;
+};
+
+[[nodiscard]] _LIBCPP_HIDE_FROM_ABI inline __floating_decimal_32 __f2d(const uint32_t __ieeeMantissa, const uint32_t __ieeeExponent) {
+  int32_t __e2;
+  uint32_t __m2;
+  if (__ieeeExponent == 0) {
+    // We subtract 2 so that the bounds computation has 2 additional bits.
+    __e2 = 1 - __FLOAT_BIAS - __FLOAT_MANTISSA_BITS - 2;
+    __m2 = __ieeeMantissa;
+  } else {
+    __e2 = static_cast<int32_t>(__ieeeExponent) - __FLOAT_BIAS - __FLOAT_MANTISSA_BITS - 2;
+    __m2 = (1u << __FLOAT_MANTISSA_BITS) | __ieeeMantissa;
+  }
+  const bool __even = (__m2 & 1) == 0;
+  const bool __acceptBounds = __even;
+
+  // Step 2: Determine the interval of valid decimal representations.
+  const uint32_t __mv = 4 * __m2;
+  const uint32_t __mp = 4 * __m2 + 2;
+  // Implicit bool -> int conversion. True is 1, false is 0.
+  const uint32_t __mmShift = __ieeeMantissa != 0 || __ieeeExponent <= 1;
+  const uint32_t __mm = 4 * __m2 - 1 - __mmShift;
+
+  // Step 3: Convert to a decimal power base using 64-bit arithmetic.
+  uint32_t __vr, __vp, __vm;
+  int32_t __e10;
+  bool __vmIsTrailingZeros = false;
+  bool __vrIsTrailingZeros = false;
+  uint8_t __lastRemovedDigit = 0;
+  if (__e2 >= 0) {
+    const uint32_t __q = __log10Pow2(__e2);
+    __e10 = static_cast<int32_t>(__q);
+    const int32_t __k = __FLOAT_POW5_INV_BITCOUNT + __pow5bits(static_cast<int32_t>(__q)) - 1;
+    const int32_t __i = -__e2 + static_cast<int32_t>(__q) + __k;
+    __vr = __mulPow5InvDivPow2(__mv, __q, __i);
+    __vp = __mulPow5InvDivPow2(__mp, __q, __i);
+    __vm = __mulPow5InvDivPow2(__mm, __q, __i);
+    if (__q != 0 && (__vp - 1) / 10 <= __vm / 10) {
+      // We need to know one removed digit even if we are not going to loop below. We could use
+      // __q = X - 1 above, except that would require 33 bits for the result, and we've found that
+      // 32-bit arithmetic is faster even on 64-bit machines.
+      const int32_t __l = __FLOAT_POW5_INV_BITCOUNT + __pow5bits(static_cast<int32_t>(__q - 1)) - 1;
+      __lastRemovedDigit = static_cast<uint8_t>(__mulPow5InvDivPow2(__mv, __q - 1,
+        -__e2 + static_cast<int32_t>(__q) - 1 + __l) % 10);
+    }
+    if (__q <= 9) {
+      // The largest power of 5 that fits in 24 bits is 5^10, but __q <= 9 seems to be safe as well.
+      // Only one of __mp, __mv, and __mm can be a multiple of 5, if any.
+      if (__mv % 5 == 0) {
+        __vrIsTrailingZeros = __multipleOfPowerOf5(__mv, __q);
+      } else if (__acceptBounds) {
+        __vmIsTrailingZeros = __multipleOfPowerOf5(__mm, __q);
+      } else {
+        __vp -= __multipleOfPowerOf5(__mp, __q);
+      }
+    }
+  } else {
+    const uint32_t __q = __log10Pow5(-__e2);
+    __e10 = static_cast<int32_t>(__q) + __e2;
+    const int32_t __i = -__e2 - static_cast<int32_t>(__q);
+    const int32_t __k = __pow5bits(__i) - __FLOAT_POW5_BITCOUNT;
+    int32_t __j = static_cast<int32_t>(__q) - __k;
+    __vr = __mulPow5divPow2(__mv, static_cast<uint32_t>(__i), __j);
+    __vp = __mulPow5divPow2(__mp, static_cast<uint32_t>(__i), __j);
+    __vm = __mulPow5divPow2(__mm, static_cast<uint32_t>(__i), __j);
+    if (__q != 0 && (__vp - 1) / 10 <= __vm / 10) {
+      __j = static_cast<int32_t>(__q) - 1 - (__pow5bits(__i + 1) - __FLOAT_POW5_BITCOUNT);
+      __lastRemovedDigit = static_cast<uint8_t>(__mulPow5divPow2(__mv, static_cast<uint32_t>(__i + 1), __j) % 10);
+    }
+    if (__q <= 1) {
+      // {__vr,__vp,__vm} is trailing zeros if {__mv,__mp,__mm} has at least __q trailing 0 bits.
+      // __mv = 4 * __m2, so it always has at least two trailing 0 bits.
+      __vrIsTrailingZeros = true;
+      if (__acceptBounds) {
+        // __mm = __mv - 1 - __mmShift, so it has 1 trailing 0 bit iff __mmShift == 1.
+        __vmIsTrailingZeros = __mmShift == 1;
+      } else {
+        // __mp = __mv + 2, so it always has at least one trailing 0 bit.
+        --__vp;
+      }
+    } else if (__q < 31) { // TRANSITION(ulfjack): Use a tighter bound here.
+      __vrIsTrailingZeros = __multipleOfPowerOf2(__mv, __q - 1);
+    }
+  }
+
+  // Step 4: Find the shortest decimal representation in the interval of valid representations.
+  int32_t __removed = 0;
+  uint32_t _Output;
+  if (__vmIsTrailingZeros || __vrIsTrailingZeros) {
+    // General case, which happens rarely (~4.0%).
+    while (__vp / 10 > __vm / 10) {
+#ifdef __clang__ // TRANSITION, LLVM-23106
+      __vmIsTrailingZeros &= __vm - (__vm / 10) * 10 == 0;
+#else
+      __vmIsTrailingZeros &= __vm % 10 == 0;
+#endif
+      __vrIsTrailingZeros &= __lastRemovedDigit == 0;
+      __lastRemovedDigit = static_cast<uint8_t>(__vr % 10);
+      __vr /= 10;
+      __vp /= 10;
+      __vm /= 10;
+      ++__removed;
+    }
+    if (__vmIsTrailingZeros) {
+      while (__vm % 10 == 0) {
+        __vrIsTrailingZeros &= __lastRemovedDigit == 0;
+        __lastRemovedDigit = static_cast<uint8_t>(__vr % 10);
+        __vr /= 10;
+        __vp /= 10;
+        __vm /= 10;
+        ++__removed;
+      }
+    }
+    if (__vrIsTrailingZeros && __lastRemovedDigit == 5 && __vr % 2 == 0) {
+      // Round even if the exact number is .....50..0.
+      __lastRemovedDigit = 4;
+    }
+    // We need to take __vr + 1 if __vr is outside bounds or we need to round up.
+    _Output = __vr + ((__vr == __vm && (!__acceptBounds || !__vmIsTrailingZeros)) || __lastRemovedDigit >= 5);
+  } else {
+    // Specialized for the common case (~96.0%). Percentages below are relative to this.
+    // Loop iterations below (approximately):
+    // 0: 13.6%, 1: 70.7%, 2: 14.1%, 3: 1.39%, 4: 0.14%, 5+: 0.01%
+    while (__vp / 10 > __vm / 10) {
+      __lastRemovedDigit = static_cast<uint8_t>(__vr % 10);
+      __vr /= 10;
+      __vp /= 10;
+      __vm /= 10;
+      ++__removed;
+    }
+    // We need to take __vr + 1 if __vr is outside bounds or we need to round up.
+    _Output = __vr + (__vr == __vm || __lastRemovedDigit >= 5);
+  }
+  const int32_t __exp = __e10 + __removed;
+
+  __floating_decimal_32 __fd;
+  __fd.__exponent = __exp;
+  __fd.__mantissa = _Output;
+  return __fd;
+}
+
+[[nodiscard]] _LIBCPP_HIDE_FROM_ABI inline to_chars_result _Large_integer_to_chars(char* const _First, char* const _Last,
+  const uint32_t _Mantissa2, const int32_t _Exponent2) {
+
+  // Print the integer _Mantissa2 * 2^_Exponent2 exactly.
+
+  // For nonzero integers, _Exponent2 >= -23. (The minimum value occurs when _Mantissa2 * 2^_Exponent2 is 1.
+  // In that case, _Mantissa2 is the implicit 1 bit followed by 23 zeros, so _Exponent2 is -23 to shift away
+  // the zeros.) The dense range of exactly representable integers has negative or zero exponents
+  // (as positive exponents make the range non-dense). For that dense range, Ryu will always be used:
+  // every digit is necessary to uniquely identify the value, so Ryu must print them all.
+
+  // Positive exponents are the non-dense range of exactly representable integers.
+  // This contains all of the values for which Ryu can't be used (and a few Ryu-friendly values).
+
+  // Performance note: Long division appears to be faster than losslessly widening float to double and calling
+  // __d2fixed_buffered_n(). If __f2fixed_buffered_n() is implemented, it might be faster than long division.
+
+  _LIBCPP_ASSERT(_Exponent2 > 0, "");
+  _LIBCPP_ASSERT(_Exponent2 <= 104, ""); // because __ieeeExponent <= 254
+
+  // Manually represent _Mantissa2 * 2^_Exponent2 as a large integer. _Mantissa2 is always 24 bits
+  // (due to the implicit bit), while _Exponent2 indicates a shift of at most 104 bits.
+  // 24 + 104 equals 128 equals 4 * 32, so we need exactly 4 32-bit elements.
+  // We use a little-endian representation, visualized like this:
+
+  // << left shift <<
+  // most significant
+  // _Data[3] _Data[2] _Data[1] _Data[0]
+  //                   least significant
+  //                   >> right shift >>
+
+  constexpr uint32_t _Data_size = 4;
+  uint32_t _Data[_Data_size]{};
+
+  // _Maxidx is the index of the most significant nonzero element.
+  uint32_t _Maxidx = ((24 + static_cast<uint32_t>(_Exponent2) + 31) / 32) - 1;
+  _LIBCPP_ASSERT(_Maxidx < _Data_size, "");
+
+  const uint32_t _Bit_shift = static_cast<uint32_t>(_Exponent2) % 32;
+  if (_Bit_shift <= 8) { // _Mantissa2's 24 bits don't cross an element boundary
+    _Data[_Maxidx] = _Mantissa2 << _Bit_shift;
+  } else { // _Mantissa2's 24 bits cross an element boundary
+    _Data[_Maxidx - 1] = _Mantissa2 << _Bit_shift;
+    _Data[_Maxidx] = _Mantissa2 >> (32 - _Bit_shift);
+  }
+
+  // If Ryu hasn't determined the total output length, we need to buffer the digits generated from right to left
+  // by long division. The largest possible float is: 340'282346638'528859811'704183484'516925440
+  uint32_t _Blocks[4];
+  int32_t _Filled_blocks = 0;
+  // From left to right, we're going to print:
+  // _Data[0] will be [1, 10] digits.
+  // Then if _Filled_blocks > 0:
+  // _Blocks[_Filled_blocks - 1], ..., _Blocks[0] will be 0-filled 9-digit blocks.
+
+  if (_Maxidx != 0) { // If the integer is actually large, perform long division.
+                      // Otherwise, skip to printing _Data[0].
+    for (;;) {
+      // Loop invariant: _Maxidx != 0 (i.e. the integer is actually large)
+
+      const uint32_t _Most_significant_elem = _Data[_Maxidx];
+      const uint32_t _Initial_remainder = _Most_significant_elem % 1000000000;
+      const uint32_t _Initial_quotient = _Most_significant_elem / 1000000000;
+      _Data[_Maxidx] = _Initial_quotient;
+      uint64_t _Remainder = _Initial_remainder;
+
+      // Process less significant elements.
+      uint32_t _Idx = _Maxidx;
+      do {
+        --_Idx; // Initially, _Remainder is at most 10^9 - 1.
+
+        // Now, _Remainder is at most (10^9 - 1) * 2^32 + 2^32 - 1, simplified to 10^9 * 2^32 - 1.
+        _Remainder = (_Remainder << 32) | _Data[_Idx];
+
+        // floor((10^9 * 2^32 - 1) / 10^9) == 2^32 - 1, so uint32_t _Quotient is lossless.
+        const uint32_t _Quotient = static_cast<uint32_t>(__div1e9(_Remainder));
+
+        // _Remainder is at most 10^9 - 1 again.
+        // For uint32_t truncation, see the __mod1e9() comment in d2s_intrinsics.h.
+        _Remainder = static_cast<uint32_t>(_Remainder) - 1000000000u * _Quotient;
+
+        _Data[_Idx] = _Quotient;
+      } while (_Idx != 0);
+
+      // Store a 0-filled 9-digit block.
+      _Blocks[_Filled_blocks++] = static_cast<uint32_t>(_Remainder);
+
+      if (_Initial_quotient == 0) { // Is the large integer shrinking?
+        --_Maxidx; // log2(10^9) is 29.9, so we can't shrink by more than one element.
+        if (_Maxidx == 0) {
+          break; // We've finished long division. Now we need to print _Data[0].
+        }
+      }
+    }
+  }
+
+  _LIBCPP_ASSERT(_Data[0] != 0, "");
+  for (uint32_t _Idx = 1; _Idx < _Data_size; ++_Idx) {
+    _LIBCPP_ASSERT(_Data[_Idx] == 0, "");
+  }
+
+  const uint32_t _Data_olength = _Data[0] >= 1000000000 ? 10 : __decimalLength9(_Data[0]);
+  const uint32_t _Total_fixed_length = _Data_olength + 9 * _Filled_blocks;
+
+  if (_Last - _First < static_cast<ptrdiff_t>(_Total_fixed_length)) {
+    return { _Last, errc::value_too_large };
+  }
+
+  char* _Result = _First;
+
+  // Print _Data[0]. While it's up to 10 digits,
+  // which is more than Ryu generates, the code below can handle this.
+  __append_n_digits(_Data_olength, _Data[0], _Result);
+  _Result += _Data_olength;
+
+  // Print 0-filled 9-digit blocks.
+  for (int32_t _Idx = _Filled_blocks - 1; _Idx >= 0; --_Idx) {
+    __append_nine_digits(_Blocks[_Idx], _Result);
+    _Result += 9;
+  }
+
+  return { _Result, errc{} };
+}
+
+[[nodiscard]] _LIBCPP_HIDE_FROM_ABI inline to_chars_result __to_chars(char* const _First, char* const _Last, const __floating_decimal_32 __v,
+  chars_format _Fmt, const uint32_t __ieeeMantissa, const uint32_t __ieeeExponent) {
+  // Step 5: Print the decimal representation.
+  uint32_t _Output = __v.__mantissa;
+  int32_t _Ryu_exponent = __v.__exponent;
+  const uint32_t __olength = __decimalLength9(_Output);
+  int32_t _Scientific_exponent = _Ryu_exponent + static_cast<int32_t>(__olength) - 1;
+
+  if (_Fmt == chars_format{}) {
+    int32_t _Lower;
+    int32_t _Upper;
+
+    if (__olength == 1) {
+      // Value | Fixed   | Scientific
+      // 1e-3  | "0.001" | "1e-03"
+      // 1e4   | "10000" | "1e+04"
+      _Lower = -3;
+      _Upper = 4;
+    } else {
+      // Value   | Fixed       | Scientific
+      // 1234e-7 | "0.0001234" | "1.234e-04"
+      // 1234e5  | "123400000" | "1.234e+08"
+      _Lower = -static_cast<int32_t>(__olength + 3);
+      _Upper = 5;
+    }
+
+    if (_Lower <= _Ryu_exponent && _Ryu_exponent <= _Upper) {
+      _Fmt = chars_format::fixed;
+    } else {
+      _Fmt = chars_format::scientific;
+    }
+  } else if (_Fmt == chars_format::general) {
+    // C11 7.21.6.1 "The fprintf function"/8:
+    // "Let P equal [...] 6 if the precision is omitted [...].
+    // Then, if a conversion with style E would have an exponent of X:
+    // - if P > X >= -4, the conversion is with style f [...].
+    // - otherwise, the conversion is with style e [...]."
+    if (-4 <= _Scientific_exponent && _Scientific_exponent < 6) {
+      _Fmt = chars_format::fixed;
+    } else {
+      _Fmt = chars_format::scientific;
+    }
+  }
+
+  if (_Fmt == chars_format::fixed) {
+    // Example: _Output == 1729, __olength == 4
+
+    // _Ryu_exponent | Printed  | _Whole_digits | _Total_fixed_length  | Notes
+    // --------------|----------|---------------|----------------------|---------------------------------------
+    //             2 | 172900   |  6            | _Whole_digits        | Ryu can't be used for printing
+    //             1 | 17290    |  5            | (sometimes adjusted) | when the trimmed digits are nonzero.
+    // --------------|----------|---------------|----------------------|---------------------------------------
+    //             0 | 1729     |  4            | _Whole_digits        | Unified length cases.
+    // --------------|----------|---------------|----------------------|---------------------------------------
+    //            -1 | 172.9    |  3            | __olength + 1        | This case can't happen for
+    //            -2 | 17.29    |  2            |                      | __olength == 1, but no additional
+    //            -3 | 1.729    |  1            |                      | code is needed to avoid it.
+    // --------------|----------|---------------|----------------------|---------------------------------------
+    //            -4 | 0.1729   |  0            | 2 - _Ryu_exponent    | C11 7.21.6.1 "The fprintf function"/8:
+    //            -5 | 0.01729  | -1            |                      | "If a decimal-point character appears,
+    //            -6 | 0.001729 | -2            |                      | at least one digit appears before it."
+
+    const int32_t _Whole_digits = static_cast<int32_t>(__olength) + _Ryu_exponent;
+
+    uint32_t _Total_fixed_length;
+    if (_Ryu_exponent >= 0) { // cases "172900" and "1729"
+      _Total_fixed_length = static_cast<uint32_t>(_Whole_digits);
+      if (_Output == 1) {
+        // Rounding can affect the number of digits.
+        // For example, 1e11f is exactly "99999997952" which is 11 digits instead of 12.
+        // We can use a lookup table to detect this and adjust the total length.
+        static constexpr uint8_t _Adjustment[39] = {
+          0,0,0,0,0,0,0,0,0,0,0,1,1,1,0,1,0,1,1,1,0,0,1,1,0,1,0,1,1,0,0,1,0,1,1,0,1,1,1 };
+        _Total_fixed_length -= _Adjustment[_Ryu_exponent];
+        // _Whole_digits doesn't need to be adjusted because these cases won't refer to it later.
+      }
+    } else if (_Whole_digits > 0) { // case "17.29"
+      _Total_fixed_length = __olength + 1;
+    } else { // case "0.001729"
+      _Total_fixed_length = static_cast<uint32_t>(2 - _Ryu_exponent);
+    }
+
+    if (_Last - _First < static_cast<ptrdiff_t>(_Total_fixed_length)) {
+      return { _Last, errc::value_too_large };
+    }
+
+    char* _Mid;
+    if (_Ryu_exponent > 0) { // case "172900"
+      bool _Can_use_ryu;
+
+      if (_Ryu_exponent > 10) { // 10^10 is the largest power of 10 that's exactly representable as a float.
+        _Can_use_ryu = false;
+      } else {
+        // Ryu generated X: __v.__mantissa * 10^_Ryu_exponent
+        // __v.__mantissa == 2^_Trailing_zero_bits * (__v.__mantissa >> _Trailing_zero_bits)
+        // 10^_Ryu_exponent == 2^_Ryu_exponent * 5^_Ryu_exponent
+
+        // _Trailing_zero_bits is [0, 29] (aside: because 2^29 is the largest power of 2
+        // with 9 decimal digits, which is float's round-trip limit.)
+        // _Ryu_exponent is [1, 10].
+        // Normalization adds [2, 23] (aside: at least 2 because the pre-normalized mantissa is at least 5).
+        // This adds up to [3, 62], which is well below float's maximum binary exponent 127.
+
+        // Therefore, we just need to consider (__v.__mantissa >> _Trailing_zero_bits) * 5^_Ryu_exponent.
+
+        // If that product would exceed 24 bits, then X can't be exactly represented as a float.
+        // (That's not a problem for round-tripping, because X is close enough to the original float,
+        // but X isn't mathematically equal to the original float.) This requires a high-precision fallback.
+
+        // If the product is 24 bits or smaller, then X can be exactly represented as a float (and we don't
+        // need to re-synthesize it; the original float must have been X, because Ryu wouldn't produce the
+        // same output for two different floats X and Y). This allows Ryu's output to be used (zero-filled).
+
+        // (2^24 - 1) / 5^0 (for indexing), (2^24 - 1) / 5^1, ..., (2^24 - 1) / 5^10
+        static constexpr uint32_t _Max_shifted_mantissa[11] = {
+          16777215, 3355443, 671088, 134217, 26843, 5368, 1073, 214, 42, 8, 1 };
+
+        unsigned long _Trailing_zero_bits;
+        (void) _BitScanForward(&_Trailing_zero_bits, __v.__mantissa); // __v.__mantissa is guaranteed nonzero
+        const uint32_t _Shifted_mantissa = __v.__mantissa >> _Trailing_zero_bits;
+        _Can_use_ryu = _Shifted_mantissa <= _Max_shifted_mantissa[_Ryu_exponent];
+      }
+
+      if (!_Can_use_ryu) {
+        const uint32_t _Mantissa2 = __ieeeMantissa | (1u << __FLOAT_MANTISSA_BITS); // restore implicit bit
+        const int32_t _Exponent2 = static_cast<int32_t>(__ieeeExponent)
+          - __FLOAT_BIAS - __FLOAT_MANTISSA_BITS; // bias and normalization
+
+        // Performance note: We've already called Ryu, so this will redundantly perform buffering and bounds checking.
+        return _Large_integer_to_chars(_First, _Last, _Mantissa2, _Exponent2);
+      }
+
+      // _Can_use_ryu
+      // Print the decimal digits, left-aligned within [_First, _First + _Total_fixed_length).
+      _Mid = _First + __olength;
+    } else { // cases "1729", "17.29", and "0.001729"
+      // Print the decimal digits, right-aligned within [_First, _First + _Total_fixed_length).
+      _Mid = _First + _Total_fixed_length;
+    }
+
+    while (_Output >= 10000) {
+#ifdef __clang__ // TRANSITION, LLVM-38217
+      const uint32_t __c = _Output - 10000 * (_Output / 10000);
+#else
+      const uint32_t __c = _Output % 10000;
+#endif
+      _Output /= 10000;
+      const uint32_t __c0 = (__c % 100) << 1;
+      const uint32_t __c1 = (__c / 100) << 1;
+      std::memcpy(_Mid -= 2, __DIGIT_TABLE + __c0, 2);
+      std::memcpy(_Mid -= 2, __DIGIT_TABLE + __c1, 2);
+    }
+    if (_Output >= 100) {
+      const uint32_t __c = (_Output % 100) << 1;
+      _Output /= 100;
+      std::memcpy(_Mid -= 2, __DIGIT_TABLE + __c, 2);
+    }
+    if (_Output >= 10) {
+      const uint32_t __c = _Output << 1;
+      std::memcpy(_Mid -= 2, __DIGIT_TABLE + __c, 2);
+    } else {
+      *--_Mid = static_cast<char>('0' + _Output);
+    }
+
+    if (_Ryu_exponent > 0) { // case "172900" with _Can_use_ryu
+      // Performance note: it might be more efficient to do this immediately after setting _Mid.
+      std::memset(_First + __olength, '0', static_cast<size_t>(_Ryu_exponent));
+    } else if (_Ryu_exponent == 0) { // case "1729"
+      // Done!
+    } else if (_Whole_digits > 0) { // case "17.29"
+      // Performance note: moving digits might not be optimal.
+      std::memmove(_First, _First + 1, static_cast<size_t>(_Whole_digits));
+      _First[_Whole_digits] = '.';
+    } else { // case "0.001729"
+      // Performance note: a larger memset() followed by overwriting '.' might be more efficient.
+      _First[0] = '0';
+      _First[1] = '.';
+      std::memset(_First + 2, '0', static_cast<size_t>(-_Whole_digits));
+    }
+
+    return { _First + _Total_fixed_length, errc{} };
+  }
+
+  const uint32_t _Total_scientific_length =
+    __olength + (__olength > 1) + 4; // digits + possible decimal point + scientific exponent
+  if (_Last - _First < static_cast<ptrdiff_t>(_Total_scientific_length)) {
+    return { _Last, errc::value_too_large };
+  }
+  char* const __result = _First;
+
+  // Print the decimal digits.
+  uint32_t __i = 0;
+  while (_Output >= 10000) {
+#ifdef __clang__ // TRANSITION, LLVM-38217
+    const uint32_t __c = _Output - 10000 * (_Output / 10000);
+#else
+    const uint32_t __c = _Output % 10000;
+#endif
+    _Output /= 10000;
+    const uint32_t __c0 = (__c % 100) << 1;
+    const uint32_t __c1 = (__c / 100) << 1;
+    std::memcpy(__result + __olength - __i - 1, __DIGIT_TABLE + __c0, 2);
+    std::memcpy(__result + __olength - __i - 3, __DIGIT_TABLE + __c1, 2);
+    __i += 4;
+  }
+  if (_Output >= 100) {
+    const uint32_t __c = (_Output % 100) << 1;
+    _Output /= 100;
+    std::memcpy(__result + __olength - __i - 1, __DIGIT_TABLE + __c, 2);
+    __i += 2;
+  }
+  if (_Output >= 10) {
+    const uint32_t __c = _Output << 1;
+    // We can't use memcpy here: the decimal dot goes between these two digits.
+    __result[2] = __DIGIT_TABLE[__c + 1];
+    __result[0] = __DIGIT_TABLE[__c];
+  } else {
+    __result[0] = static_cast<char>('0' + _Output);
+  }
+
+  // Print decimal point if needed.
+  uint32_t __index;
+  if (__olength > 1) {
+    __result[1] = '.';
+    __index = __olength + 1;
+  } else {
+    __index = 1;
+  }
+
+  // Print the exponent.
+  __result[__index++] = 'e';
+  if (_Scientific_exponent < 0) {
+    __result[__index++] = '-';
+    _Scientific_exponent = -_Scientific_exponent;
+  } else {
+    __result[__index++] = '+';
+  }
+
+  std::memcpy(__result + __index, __DIGIT_TABLE + 2 * _Scientific_exponent, 2);
+  __index += 2;
+
+  return { _First + _Total_scientific_length, errc{} };
+}
+
+[[nodiscard]] to_chars_result __f2s_buffered_n(char* const _First, char* const _Last, const float __f,
+  const chars_format _Fmt) {
+
+  // Step 1: Decode the floating-point number, and unify normalized and subnormal cases.
+  const uint32_t __bits = __float_to_bits(__f);
+
+  // Case distinction; exit early for the easy cases.
+  if (__bits == 0) {
+    if (_Fmt == chars_format::scientific) {
+      if (_Last - _First < 5) {
+        return { _Last, errc::value_too_large };
+      }
+
+      std::memcpy(_First, "0e+00", 5);
+
+      return { _First + 5, errc{} };
+    }
+
+    // Print "0" for chars_format::fixed, chars_format::general, and chars_format{}.
+    if (_First == _Last) {
+      return { _Last, errc::value_too_large };
+    }
+
+    *_First = '0';
+
+    return { _First + 1, errc{} };
+  }
+
+  // Decode __bits into mantissa and exponent.
+  const uint32_t __ieeeMantissa = __bits & ((1u << __FLOAT_MANTISSA_BITS) - 1);
+  const uint32_t __ieeeExponent = __bits >> __FLOAT_MANTISSA_BITS;
+
+  // When _Fmt == chars_format::fixed and the floating-point number is a large integer,
+  // it's faster to skip Ryu and immediately print the integer exactly.
+  if (_Fmt == chars_format::fixed) {
+    const uint32_t _Mantissa2 = __ieeeMantissa | (1u << __FLOAT_MANTISSA_BITS); // restore implicit bit
+    const int32_t _Exponent2 = static_cast<int32_t>(__ieeeExponent)
+      - __FLOAT_BIAS - __FLOAT_MANTISSA_BITS; // bias and normalization
+
+    // Normal values are equal to _Mantissa2 * 2^_Exponent2.
+    // (Subnormals are different, but they'll be rejected by the _Exponent2 test here, so they can be ignored.)
+
+    if (_Exponent2 > 0) {
+      return _Large_integer_to_chars(_First, _Last, _Mantissa2, _Exponent2);
+    }
+  }
+
+  const __floating_decimal_32 __v = __f2d(__ieeeMantissa, __ieeeExponent);
+  return __to_chars(_First, _Last, __v, _Fmt, __ieeeMantissa, __ieeeExponent);
+}
+
+_LIBCPP_END_NAMESPACE_STD
+
+// clang-format on

third_party/libcxx/src/shared_mutex.cpp

@@ -0,0 +1,120 @@
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#include <__config>
+
+#ifndef _LIBCPP_HAS_NO_THREADS
+
+#include <mutex>
+#include <shared_mutex>
+#if defined(__ELF__) && defined(_LIBCPP_LINK_PTHREAD_LIB)
+#  pragma comment(lib, "pthread")
+#endif
+
+_LIBCPP_BEGIN_NAMESPACE_STD
+
+// Shared Mutex Base
+__shared_mutex_base::__shared_mutex_base()
+    : __state_(0)
+{
+}
+
+// Exclusive ownership
+
+void
+__shared_mutex_base::lock()
+{
+    unique_lock<mutex> lk(__mut_);
+    while (__state_ & __write_entered_)
+        __gate1_.wait(lk);
+    __state_ |= __write_entered_;
+    while (__state_ & __n_readers_)
+        __gate2_.wait(lk);
+}
+
+bool
+__shared_mutex_base::try_lock()
+{
+    unique_lock<mutex> lk(__mut_);
+    if (__state_ == 0)
+    {
+        __state_ = __write_entered_;
+        return true;
+    }
+    return false;
+}
+
+void
+__shared_mutex_base::unlock()
+{
+    lock_guard<mutex> _(__mut_);
+    __state_ = 0;
+    __gate1_.notify_all();
+}
+
+// Shared ownership
+
+void
+__shared_mutex_base::lock_shared()
+{
+    unique_lock<mutex> lk(__mut_);
+    while ((__state_ & __write_entered_) || (__state_ & __n_readers_) == __n_readers_)
+        __gate1_.wait(lk);
+    unsigned num_readers = (__state_ & __n_readers_) + 1;
+    __state_ &= ~__n_readers_;
+    __state_ |= num_readers;
+}
+
+bool
+__shared_mutex_base::try_lock_shared()
+{
+    unique_lock<mutex> lk(__mut_);
+    unsigned num_readers = __state_ & __n_readers_;
+    if (!(__state_ & __write_entered_) && num_readers != __n_readers_)
+    {
+        ++num_readers;
+        __state_ &= ~__n_readers_;
+        __state_ |= num_readers;
+        return true;
+    }
+    return false;
+}
+
+void
+__shared_mutex_base::unlock_shared()
+{
+    lock_guard<mutex> _(__mut_);
+    unsigned num_readers = (__state_ & __n_readers_) - 1;
+    __state_ &= ~__n_readers_;
+    __state_ |= num_readers;
+    if (__state_ & __write_entered_)
+    {
+        if (num_readers == 0)
+            __gate2_.notify_one();
+    }
+    else
+    {
+        if (num_readers == __n_readers_ - 1)
+            __gate1_.notify_one();
+    }
+}
+
+
+// Shared Timed Mutex
+// These routines are here for ABI stability
+shared_timed_mutex::shared_timed_mutex() : __base_() {}
+void shared_timed_mutex::lock()     { return __base_.lock(); }
+bool shared_timed_mutex::try_lock() { return __base_.try_lock(); }
+void shared_timed_mutex::unlock()   { return __base_.unlock(); }
+void shared_timed_mutex::lock_shared() { return __base_.lock_shared(); }
+bool shared_timed_mutex::try_lock_shared() { return __base_.try_lock_shared(); }
+void shared_timed_mutex::unlock_shared() { return __base_.unlock_shared(); }
+
+_LIBCPP_END_NAMESPACE_STD
+
+#endif // !_LIBCPP_HAS_NO_THREADS

third_party/libcxx/src/std_stream.h

@@ -0,0 +1,361 @@
+// -*- C++ -*-
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef _LIBCPP_STD_STREAM_H
+#define _LIBCPP_STD_STREAM_H
+
+#include <__config>
+#include <__locale>
+#include <cstdio>
+#include <istream>
+#include <ostream>
+
+#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
+#  pragma GCC system_header
+#endif
+
+_LIBCPP_PUSH_MACROS
+#include <__undef_macros>
+
+
+_LIBCPP_BEGIN_NAMESPACE_STD
+
+static const int __limit = 8;
+
+// __stdinbuf
+
+template <class _CharT>
+class _LIBCPP_HIDDEN __stdinbuf
+    : public basic_streambuf<_CharT, char_traits<_CharT> >
+{
+public:
+    typedef _CharT                           char_type;
+    typedef char_traits<char_type>           traits_type;
+    typedef typename traits_type::int_type   int_type;
+    typedef typename traits_type::pos_type   pos_type;
+    typedef typename traits_type::off_type   off_type;
+    typedef typename traits_type::state_type state_type;
+
+    __stdinbuf(FILE* __fp, state_type* __st);
+
+protected:
+    virtual int_type underflow();
+    virtual int_type uflow();
+    virtual int_type pbackfail(int_type __c = traits_type::eof());
+    virtual void imbue(const locale& __loc);
+
+private:
+
+    FILE* __file_;
+    const codecvt<char_type, char, state_type>* __cv_;
+    state_type* __st_;
+    int __encoding_;
+    int_type __last_consumed_;
+    bool __last_consumed_is_next_;
+    bool __always_noconv_;
+
+    __stdinbuf(const __stdinbuf&);
+    __stdinbuf& operator=(const __stdinbuf&);
+
+    int_type __getchar(bool __consume);
+};
+
+template <class _CharT>
+__stdinbuf<_CharT>::__stdinbuf(FILE* __fp, state_type* __st)
+    : __file_(__fp),
+      __st_(__st),
+      __last_consumed_(traits_type::eof()),
+      __last_consumed_is_next_(false)
+{
+    imbue(this->getloc());
+}
+
+template <class _CharT>
+void
+__stdinbuf<_CharT>::imbue(const locale& __loc)
+{
+    __cv_ = &use_facet<codecvt<char_type, char, state_type> >(__loc);
+    __encoding_ = __cv_->encoding();
+    __always_noconv_ = __cv_->always_noconv();
+    if (__encoding_ > __limit)
+        __throw_runtime_error("unsupported locale for standard input");
+}
+
+template <class _CharT>
+typename __stdinbuf<_CharT>::int_type
+__stdinbuf<_CharT>::underflow()
+{
+    return __getchar(false);
+}
+
+template <class _CharT>
+typename __stdinbuf<_CharT>::int_type
+__stdinbuf<_CharT>::uflow()
+{
+    return __getchar(true);
+}
+
+template <class _CharT>
+typename __stdinbuf<_CharT>::int_type
+__stdinbuf<_CharT>::__getchar(bool __consume)
+{
+    if (__last_consumed_is_next_)
+    {
+        int_type __result = __last_consumed_;
+        if (__consume)
+        {
+            __last_consumed_ = traits_type::eof();
+            __last_consumed_is_next_ = false;
+        }
+        return __result;
+    }
+    char __extbuf[__limit];
+    int __nread = _VSTD::max(1, __encoding_);
+    for (int __i = 0; __i < __nread; ++__i)
+    {
+        int __c = getc(__file_);
+        if (__c == EOF)
+            return traits_type::eof();
+        __extbuf[__i] = static_cast<char>(__c);
+    }
+    char_type __1buf;
+    if (__always_noconv_)
+        __1buf = static_cast<char_type>(__extbuf[0]);
+    else
+    {
+        const char* __enxt;
+        char_type* __inxt;
+        codecvt_base::result __r;
+        do
+        {
+            state_type __sv_st = *__st_;
+            __r = __cv_->in(*__st_, __extbuf, __extbuf + __nread, __enxt,
+                                   &__1buf, &__1buf + 1, __inxt);
+            switch (__r)
+            {
+            case _VSTD::codecvt_base::ok:
+                break;
+            case codecvt_base::partial:
+                *__st_ = __sv_st;
+                if (__nread == sizeof(__extbuf))
+                    return traits_type::eof();
+                {
+                    int __c = getc(__file_);
+                    if (__c == EOF)
+                        return traits_type::eof();
+                    __extbuf[__nread] = static_cast<char>(__c);
+                }
+                ++__nread;
+                break;
+            case codecvt_base::error:
+                return traits_type::eof();
+            case _VSTD::codecvt_base::noconv:
+                __1buf = static_cast<char_type>(__extbuf[0]);
+                break;
+            }
+        } while (__r == _VSTD::codecvt_base::partial);
+    }
+    if (!__consume)
+    {
+        for (int __i = __nread; __i > 0;)
+        {
+            if (ungetc(traits_type::to_int_type(__extbuf[--__i]), __file_) == EOF)
+                return traits_type::eof();
+        }
+    }
+    else
+        __last_consumed_ = traits_type::to_int_type(__1buf);
+    return traits_type::to_int_type(__1buf);
+}
+
+template <class _CharT>
+typename __stdinbuf<_CharT>::int_type
+__stdinbuf<_CharT>::pbackfail(int_type __c)
+{
+    if (traits_type::eq_int_type(__c, traits_type::eof()))
+    {
+        if (!__last_consumed_is_next_)
+        {
+            __c = __last_consumed_;
+            __last_consumed_is_next_ = !traits_type::eq_int_type(__last_consumed_,
+                                                                 traits_type::eof());
+        }
+        return __c;
+    }
+    if (__last_consumed_is_next_)
+    {
+        char __extbuf[__limit];
+        char* __enxt;
+        const char_type __ci = traits_type::to_char_type(__last_consumed_);
+        const char_type* __inxt;
+        switch (__cv_->out(*__st_, &__ci, &__ci + 1, __inxt,
+                                  __extbuf, __extbuf + sizeof(__extbuf), __enxt))
+        {
+        case _VSTD::codecvt_base::ok:
+            break;
+        case _VSTD::codecvt_base::noconv:
+            __extbuf[0] = static_cast<char>(__last_consumed_);
+            __enxt = __extbuf + 1;
+            break;
+        case codecvt_base::partial:
+        case codecvt_base::error:
+            return traits_type::eof();
+        }
+        while (__enxt > __extbuf)
+            if (ungetc(*--__enxt, __file_) == EOF)
+                return traits_type::eof();
+    }
+    __last_consumed_ = __c;
+    __last_consumed_is_next_ = true;
+    return __c;
+}
+
+// __stdoutbuf
+
+template <class _CharT>
+class _LIBCPP_HIDDEN __stdoutbuf
+    : public basic_streambuf<_CharT, char_traits<_CharT> >
+{
+public:
+    typedef _CharT                           char_type;
+    typedef char_traits<char_type>           traits_type;
+    typedef typename traits_type::int_type   int_type;
+    typedef typename traits_type::pos_type   pos_type;
+    typedef typename traits_type::off_type   off_type;
+    typedef typename traits_type::state_type state_type;
+
+    __stdoutbuf(FILE* __fp, state_type* __st);
+
+protected:
+    virtual int_type overflow (int_type __c = traits_type::eof());
+    virtual streamsize xsputn(const char_type* __s, streamsize __n);
+    virtual int sync();
+    virtual void imbue(const locale& __loc);
+
+private:
+    FILE* __file_;
+    const codecvt<char_type, char, state_type>* __cv_;
+    state_type* __st_;
+    bool __always_noconv_;
+
+    __stdoutbuf(const __stdoutbuf&);
+    __stdoutbuf& operator=(const __stdoutbuf&);
+};
+
+template <class _CharT>
+__stdoutbuf<_CharT>::__stdoutbuf(FILE* __fp, state_type* __st)
+    : __file_(__fp),
+      __cv_(&use_facet<codecvt<char_type, char, state_type> >(this->getloc())),
+      __st_(__st),
+      __always_noconv_(__cv_->always_noconv())
+{
+}
+
+template <class _CharT>
+typename __stdoutbuf<_CharT>::int_type
+__stdoutbuf<_CharT>::overflow(int_type __c)
+{
+    char __extbuf[__limit];
+    char_type __1buf;
+    if (!traits_type::eq_int_type(__c, traits_type::eof()))
+    {
+        __1buf = traits_type::to_char_type(__c);
+        if (__always_noconv_)
+        {
+            if (fwrite(&__1buf, sizeof(char_type), 1, __file_) != 1)
+                return traits_type::eof();
+        }
+        else
+        {
+            char* __extbe = __extbuf;
+            codecvt_base::result __r;
+            char_type* pbase = &__1buf;
+            char_type* pptr = pbase + 1;
+            do
+            {
+                const char_type* __e;
+                __r = __cv_->out(*__st_, pbase, pptr, __e,
+                                        __extbuf,
+                                        __extbuf + sizeof(__extbuf),
+                                        __extbe);
+                if (__e == pbase)
+                    return traits_type::eof();
+                if (__r == codecvt_base::noconv)
+                {
+                    if (fwrite(pbase, 1, 1, __file_) != 1)
+                        return traits_type::eof();
+                }
+                else if (__r == codecvt_base::ok || __r == codecvt_base::partial)
+                {
+                    size_t __nmemb = static_cast<size_t>(__extbe - __extbuf);
+                    if (fwrite(__extbuf, 1, __nmemb, __file_) != __nmemb)
+                        return traits_type::eof();
+                    if (__r == codecvt_base::partial)
+                    {
+                        pbase = const_cast<char_type*>(__e);
+                    }
+                }
+                else
+                    return traits_type::eof();
+            } while (__r == codecvt_base::partial);
+        }
+    }
+    return traits_type::not_eof(__c);
+}
+
+template <class _CharT>
+streamsize
+__stdoutbuf<_CharT>::xsputn(const char_type* __s, streamsize __n)
+{
+    if (__always_noconv_)
+        return fwrite(__s, sizeof(char_type), __n, __file_);
+    streamsize __i = 0;
+    for (; __i < __n; ++__i, ++__s)
+        if (overflow(traits_type::to_int_type(*__s)) == traits_type::eof())
+            break;
+    return __i;
+}
+
+template <class _CharT>
+int
+__stdoutbuf<_CharT>::sync()
+{
+    char __extbuf[__limit];
+    codecvt_base::result __r;
+    do
+    {
+        char* __extbe;
+        __r = __cv_->unshift(*__st_, __extbuf,
+                                    __extbuf + sizeof(__extbuf),
+                                    __extbe);
+        size_t __nmemb = static_cast<size_t>(__extbe - __extbuf);
+        if (fwrite(__extbuf, 1, __nmemb, __file_) != __nmemb)
+            return -1;
+    } while (__r == codecvt_base::partial);
+    if (__r == codecvt_base::error)
+        return -1;
+    if (fflush(__file_))
+        return -1;
+    return 0;
+}
+
+template <class _CharT>
+void
+__stdoutbuf<_CharT>::imbue(const locale& __loc)
+{
+    sync();
+    __cv_ = &use_facet<codecvt<char_type, char, state_type> >(__loc);
+    __always_noconv_ = __cv_->always_noconv();
+}
+
+_LIBCPP_END_NAMESPACE_STD
+
+_LIBCPP_POP_MACROS
+
+#endif // _LIBCPP_STD_STREAM_H

third_party/libcxx/src/stdexcept.cpp

@@ -0,0 +1,17 @@
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#include <new>
+#include <stdexcept>
+#include <string>
+
+#ifdef _LIBCPP_ABI_VCRUNTIME
+#include "third_party/libcxx/src/support/runtime/stdexcept_vcruntime.ipp"
+#else
+#include "third_party/libcxx/src/support/runtime/stdexcept_default.ipp"
+#endif

third_party/libcxx/src/string.cpp

@@ -0,0 +1,392 @@
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#include <__assert>
+#include <cerrno>
+#include <charconv>
+#include <cstdlib>
+#include <limits>
+#include <stdexcept>
+#include <stdio.h>
+#include <string>
+
+#ifndef _LIBCPP_HAS_NO_WIDE_CHARACTERS
+#  include <cwchar>
+#endif
+
+_LIBCPP_BEGIN_NAMESPACE_STD
+
+#ifndef _LIBCPP_ABI_DO_NOT_EXPORT_BASIC_STRING_COMMON
+
+template <bool>
+struct __basic_string_common;
+
+// The struct isn't declared anymore in the headers. It's only here for ABI compatibility.
+template <>
+struct __basic_string_common<true> {
+    _LIBCPP_NORETURN _LIBCPP_EXPORTED_FROM_ABI void __throw_length_error() const;
+    _LIBCPP_NORETURN _LIBCPP_EXPORTED_FROM_ABI void __throw_out_of_range() const;
+};
+
+void __basic_string_common<true>::__throw_length_error() const {
+    std::__throw_length_error("basic_string");
+}
+void __basic_string_common<true>::__throw_out_of_range() const {
+    std::__throw_out_of_range("basic_string");
+}
+
+#endif // _LIBCPP_ABI_DO_NOT_EXPORT_BASIC_STRING_COMMON
+
+#define _LIBCPP_EXTERN_TEMPLATE_DEFINE(...) template __VA_ARGS__;
+#ifdef _LIBCPP_ABI_STRING_OPTIMIZED_EXTERNAL_INSTANTIATION
+    _LIBCPP_STRING_UNSTABLE_EXTERN_TEMPLATE_LIST(_LIBCPP_EXTERN_TEMPLATE_DEFINE, char)
+#   ifndef _LIBCPP_HAS_NO_WIDE_CHARACTERS
+        _LIBCPP_STRING_UNSTABLE_EXTERN_TEMPLATE_LIST(_LIBCPP_EXTERN_TEMPLATE_DEFINE, wchar_t)
+#   endif
+#else
+    _LIBCPP_STRING_V1_EXTERN_TEMPLATE_LIST(_LIBCPP_EXTERN_TEMPLATE_DEFINE, char)
+#   ifndef _LIBCPP_HAS_NO_WIDE_CHARACTERS
+        _LIBCPP_STRING_V1_EXTERN_TEMPLATE_LIST(_LIBCPP_EXTERN_TEMPLATE_DEFINE, wchar_t)
+#   endif
+#endif
+#undef _LIBCPP_EXTERN_TEMPLATE_DEFINE
+
+template string operator+<char, char_traits<char>, allocator<char>>(char const*, string const&);
+
+namespace
+{
+
+template<typename T>
+inline void throw_helper(const string& msg) {
+#ifndef _LIBCPP_HAS_NO_EXCEPTIONS
+    throw T(msg);
+#else
+    fprintf(stderr, "%s\n", msg.c_str());
+    _VSTD::abort();
+#endif
+}
+
+inline void throw_from_string_out_of_range(const string& func) {
+    throw_helper<out_of_range>(func + ": out of range");
+}
+
+inline void throw_from_string_invalid_arg(const string& func) {
+    throw_helper<invalid_argument>(func + ": no conversion");
+}
+
+// as_integer
+
+template<typename V, typename S, typename F>
+inline V as_integer_helper(const string& func, const S& str, size_t* idx, int base, F f) {
+    typename S::value_type* ptr = nullptr;
+    const typename S::value_type* const p = str.c_str();
+    __libcpp_remove_reference_t<decltype(errno)> errno_save = errno;
+    errno = 0;
+    V r = f(p, &ptr, base);
+    swap(errno, errno_save);
+    if (errno_save == ERANGE)
+        throw_from_string_out_of_range(func);
+    if (ptr == p)
+        throw_from_string_invalid_arg(func);
+    if (idx)
+        *idx = static_cast<size_t>(ptr - p);
+    return r;
+}
+
+template<typename V, typename S>
+inline V as_integer(const string& func, const S& s, size_t* idx, int base);
+
+// string
+template<>
+inline int as_integer(const string& func, const string& s, size_t* idx, int base) {
+    // Use long as no Standard string to integer exists.
+    long r = as_integer_helper<long>(func, s, idx, base, strtol);
+    if (r < numeric_limits<int>::min() || numeric_limits<int>::max() < r)
+        throw_from_string_out_of_range(func);
+    return static_cast<int>(r);
+}
+
+template<>
+inline long as_integer(const string& func, const string& s, size_t* idx, int base) {
+    return as_integer_helper<long>(func, s, idx, base, strtol);
+}
+
+template<>
+inline unsigned long as_integer(const string& func, const string& s, size_t* idx, int base) {
+    return as_integer_helper<unsigned long>(func, s, idx, base, strtoul);
+}
+
+template<>
+inline long long as_integer(const string& func, const string& s, size_t* idx, int base) {
+    return as_integer_helper<long long>(func, s, idx, base, strtoll);
+}
+
+template<>
+inline unsigned long long as_integer(const string& func, const string& s, size_t* idx, int base) {
+    return as_integer_helper<unsigned long long>(func, s, idx, base, strtoull);
+}
+
+#ifndef _LIBCPP_HAS_NO_WIDE_CHARACTERS
+// wstring
+template<>
+inline int as_integer(const string& func, const wstring& s, size_t* idx, int base) {
+    // Use long as no Stantard string to integer exists.
+    long r = as_integer_helper<long>(func, s, idx, base, wcstol);
+    if (r < numeric_limits<int>::min() || numeric_limits<int>::max() < r)
+        throw_from_string_out_of_range(func);
+    return static_cast<int>(r);
+}
+
+template<>
+inline long as_integer(const string& func, const wstring& s, size_t* idx, int base) {
+    return as_integer_helper<long>(func, s, idx, base, wcstol);
+}
+
+template<>
+inline
+unsigned long
+as_integer(const string& func, const wstring& s, size_t* idx, int base)
+{
+    return as_integer_helper<unsigned long>(func, s, idx, base, wcstoul);
+}
+
+template<>
+inline long long as_integer(const string& func, const wstring& s, size_t* idx, int base) {
+    return as_integer_helper<long long>(func, s, idx, base, wcstoll);
+}
+
+template<>
+inline unsigned long long as_integer(const string& func, const wstring& s, size_t* idx, int base) {
+    return as_integer_helper<unsigned long long>(func, s, idx, base, wcstoull);
+}
+#endif // _LIBCPP_HAS_NO_WIDE_CHARACTERS
+
+// as_float
+
+template<typename V, typename S, typename F>
+inline V as_float_helper(const string& func, const S& str, size_t* idx, F f) {
+    typename S::value_type* ptr = nullptr;
+    const typename S::value_type* const p = str.c_str();
+    __libcpp_remove_reference_t<decltype(errno)> errno_save = errno;
+    errno = 0;
+    V r = f(p, &ptr);
+    swap(errno, errno_save);
+    if (errno_save == ERANGE)
+        throw_from_string_out_of_range(func);
+    if (ptr == p)
+        throw_from_string_invalid_arg(func);
+    if (idx)
+        *idx = static_cast<size_t>(ptr - p);
+    return r;
+}
+
+template<typename V, typename S>
+inline V as_float(const string& func, const S& s, size_t* idx = nullptr);
+
+template<>
+inline float as_float(const string& func, const string& s, size_t* idx) {
+    return as_float_helper<float>(func, s, idx, strtof);
+}
+
+template<>
+inline double as_float(const string& func, const string& s, size_t* idx) {
+    return as_float_helper<double>(func, s, idx, strtod);
+}
+
+template<>
+inline long double as_float(const string& func, const string& s, size_t* idx) {
+    return as_float_helper<long double>(func, s, idx, strtold);
+}
+
+#ifndef _LIBCPP_HAS_NO_WIDE_CHARACTERS
+template<>
+inline float as_float(const string& func, const wstring& s, size_t* idx) {
+    return as_float_helper<float>(func, s, idx, wcstof);
+}
+
+template<>
+inline double as_float(const string& func, const wstring& s, size_t* idx) {
+    return as_float_helper<double>(func, s, idx, wcstod);
+}
+
+template<>
+inline long double as_float(const string& func, const wstring& s, size_t* idx) {
+    return as_float_helper<long double>(func, s, idx, wcstold);
+}
+#endif // _LIBCPP_HAS_NO_WIDE_CHARACTERS
+
+}  // unnamed namespace
+
+int stoi(const string& str, size_t* idx, int base) {
+    return as_integer<int>("stoi", str, idx, base);
+}
+
+long stol(const string& str, size_t* idx, int base) {
+    return as_integer<long>("stol", str, idx, base);
+}
+
+unsigned long stoul(const string& str, size_t* idx, int base) {
+    return as_integer<unsigned long>("stoul", str, idx, base);
+}
+
+long long stoll(const string& str, size_t* idx, int base) {
+    return as_integer<long long>("stoll", str, idx, base);
+}
+
+unsigned long long stoull(const string& str, size_t* idx, int base) {
+    return as_integer<unsigned long long>("stoull", str, idx, base);
+}
+
+float stof(const string& str, size_t* idx) {
+    return as_float<float>("stof", str, idx);
+}
+
+double stod(const string& str, size_t* idx) {
+    return as_float<double>("stod", str, idx);
+}
+
+long double stold(const string& str, size_t* idx) {
+    return as_float<long double>("stold", str, idx);
+}
+
+#ifndef _LIBCPP_HAS_NO_WIDE_CHARACTERS
+int stoi(const wstring& str, size_t* idx, int base) {
+    return as_integer<int>("stoi", str, idx, base);
+}
+
+long stol(const wstring& str, size_t* idx, int base) {
+    return as_integer<long>("stol", str, idx, base);
+}
+
+unsigned long stoul(const wstring& str, size_t* idx, int base) {
+    return as_integer<unsigned long>("stoul", str, idx, base);
+}
+
+long long stoll(const wstring& str, size_t* idx, int base) {
+    return as_integer<long long>("stoll", str, idx, base);
+}
+
+unsigned long long stoull(const wstring& str, size_t* idx, int base) {
+    return as_integer<unsigned long long>("stoull", str, idx, base);
+}
+
+float stof(const wstring& str, size_t* idx) {
+    return as_float<float>("stof", str, idx);
+}
+
+double stod(const wstring& str, size_t* idx) {
+    return as_float<double>("stod", str, idx);
+}
+
+long double stold(const wstring& str, size_t* idx) {
+    return as_float<long double>("stold", str, idx);
+}
+#endif // !_LIBCPP_HAS_NO_WIDE_CHARACTERS
+
+// to_string
+
+namespace
+{
+
+// as_string
+
+template<typename S, typename P, typename V >
+inline S as_string(P sprintf_like, S s, const typename S::value_type* fmt, V a) {
+    typedef typename S::size_type size_type;
+    size_type available = s.size();
+    while (true) {
+        int status = sprintf_like(&s[0], available + 1, fmt, a);
+        if (status >= 0) {
+            size_type used = static_cast<size_type>(status);
+            if (used <= available) {
+                s.resize(used);
+                break;
+            }
+            available = used; // Assume this is advice of how much space we need.
+        }
+        else
+            available = available * 2 + 1;
+        s.resize(available);
+    }
+    return s;
+}
+
+template <class S>
+struct initial_string;
+
+template <>
+struct initial_string<string> {
+    string operator()() const {
+        string s;
+        s.resize(s.capacity());
+        return s;
+    }
+};
+
+#ifndef _LIBCPP_HAS_NO_WIDE_CHARACTERS
+template <>
+struct initial_string<wstring> {
+    wstring operator()() const {
+        wstring s(20, wchar_t());
+        s.resize(s.capacity());
+        return s;
+    }
+};
+
+typedef int (*wide_printf)(wchar_t* __restrict, size_t, const wchar_t*__restrict, ...);
+
+inline wide_printf get_swprintf() {
+#ifndef _LIBCPP_MSVCRT
+    return swprintf;
+#else
+    return static_cast<int (__cdecl*)(wchar_t* __restrict, size_t, const wchar_t*__restrict, ...)>(_snwprintf);
+#endif
+}
+#endif // _LIBCPP_HAS_NO_WIDE_CHARACTERS
+
+template <typename S, typename V>
+S i_to_string(V v) {
+//  numeric_limits::digits10 returns value less on 1 than desired for unsigned numbers.
+//  For example, for 1-byte unsigned value digits10 is 2 (999 can not be represented),
+//  so we need +1 here.
+    constexpr size_t bufsize = numeric_limits<V>::digits10 + 2;  // +1 for minus, +1 for digits10
+    char buf[bufsize];
+    const auto res = to_chars(buf, buf + bufsize, v);
+    _LIBCPP_ASSERT(res.ec == errc(), "bufsize must be large enough to accomodate the value");
+    return S(buf, res.ptr);
+}
+
+}  // unnamed namespace
+
+string  to_string (int val)                { return i_to_string< string>(val); }
+string  to_string (long val)               { return i_to_string< string>(val); }
+string  to_string (long long val)          { return i_to_string< string>(val); }
+string  to_string (unsigned val)           { return i_to_string< string>(val); }
+string  to_string (unsigned long val)      { return i_to_string< string>(val); }
+string  to_string (unsigned long long val) { return i_to_string< string>(val); }
+
+#ifndef _LIBCPP_HAS_NO_WIDE_CHARACTERS
+wstring to_wstring(int val)                { return i_to_string<wstring>(val); }
+wstring to_wstring(long val)               { return i_to_string<wstring>(val); }
+wstring to_wstring(long long val)          { return i_to_string<wstring>(val); }
+wstring to_wstring(unsigned val)           { return i_to_string<wstring>(val); }
+wstring to_wstring(unsigned long val)      { return i_to_string<wstring>(val); }
+wstring to_wstring(unsigned long long val) { return i_to_string<wstring>(val); }
+#endif
+
+string  to_string (float val)       { return as_string(snprintf,       initial_string< string>()(),   "%f", val); }
+string  to_string (double val)      { return as_string(snprintf,       initial_string< string>()(),   "%f", val); }
+string  to_string (long double val) { return as_string(snprintf,       initial_string< string>()(),  "%Lf", val); }
+
+#ifndef _LIBCPP_HAS_NO_WIDE_CHARACTERS
+wstring to_wstring(float val)       { return as_string(get_swprintf(), initial_string<wstring>()(),  L"%f", val); }
+wstring to_wstring(double val)      { return as_string(get_swprintf(), initial_string<wstring>()(),  L"%f", val); }
+wstring to_wstring(long double val) { return as_string(get_swprintf(), initial_string<wstring>()(), L"%Lf", val); }
+#endif
+
+_LIBCPP_END_NAMESPACE_STD

third_party/libcxx/src/strstream.cpp

@@ -0,0 +1,340 @@
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#include <__assert>
+#include <__utility/unreachable.h>
+#include <algorithm>
+#include <climits>
+#include <cstdlib>
+#include <cstring>
+#include <strstream>
+
+_LIBCPP_PUSH_MACROS
+#include <__undef_macros>
+
+_LIBCPP_BEGIN_NAMESPACE_STD
+
+strstreambuf::strstreambuf(streamsize __alsize)
+    : __strmode_(__dynamic),
+      __alsize_(__alsize),
+      __palloc_(nullptr),
+      __pfree_(nullptr)
+{
+}
+
+strstreambuf::strstreambuf(void* (*__palloc)(size_t), void (*__pfree)(void*))
+    : __strmode_(__dynamic),
+      __alsize_(__default_alsize),
+      __palloc_(__palloc),
+      __pfree_(__pfree)
+{
+}
+
+void
+strstreambuf::__init(char* __gnext, streamsize __n, char* __pbeg)
+{
+    if (__n == 0)
+        __n = static_cast<streamsize>(strlen(__gnext));
+    else if (__n < 0)
+        __n = INT_MAX;
+    if (__pbeg == nullptr)
+        setg(__gnext, __gnext, __gnext + __n);
+    else
+    {
+        setg(__gnext, __gnext, __pbeg);
+        setp(__pbeg, __pbeg + __n);
+    }
+}
+
+strstreambuf::strstreambuf(char* __gnext, streamsize __n, char* __pbeg)
+    : __strmode_(),
+      __alsize_(__default_alsize),
+      __palloc_(nullptr),
+      __pfree_(nullptr)
+{
+    __init(__gnext, __n, __pbeg);
+}
+
+strstreambuf::strstreambuf(const char* __gnext, streamsize __n)
+    : __strmode_(__constant),
+      __alsize_(__default_alsize),
+      __palloc_(nullptr),
+      __pfree_(nullptr)
+{
+    __init(const_cast<char *>(__gnext), __n, nullptr);
+}
+
+strstreambuf::strstreambuf(signed char* __gnext, streamsize __n, signed char* __pbeg)
+    : __strmode_(),
+      __alsize_(__default_alsize),
+      __palloc_(nullptr),
+      __pfree_(nullptr)
+{
+    __init(const_cast<char *>(reinterpret_cast<const char*>(__gnext)), __n, reinterpret_cast<char*>(__pbeg));
+}
+
+strstreambuf::strstreambuf(const signed char* __gnext, streamsize __n)
+    : __strmode_(__constant),
+      __alsize_(__default_alsize),
+      __palloc_(nullptr),
+      __pfree_(nullptr)
+{
+    __init(const_cast<char *>(reinterpret_cast<const char*>(__gnext)), __n, nullptr);
+}
+
+strstreambuf::strstreambuf(unsigned char* __gnext, streamsize __n, unsigned char* __pbeg)
+    : __strmode_(),
+      __alsize_(__default_alsize),
+      __palloc_(nullptr),
+      __pfree_(nullptr)
+{
+    __init(const_cast<char *>(reinterpret_cast<const char*>(__gnext)), __n, reinterpret_cast<char*>(__pbeg));
+}
+
+strstreambuf::strstreambuf(const unsigned char* __gnext, streamsize __n)
+    : __strmode_(__constant),
+      __alsize_(__default_alsize),
+      __palloc_(nullptr),
+      __pfree_(nullptr)
+{
+    __init(const_cast<char *>(reinterpret_cast<const char*>(__gnext)), __n, nullptr);
+}
+
+strstreambuf::~strstreambuf()
+{
+    if (eback() && (__strmode_ & __allocated) != 0 && (__strmode_ & __frozen) == 0)
+    {
+        if (__pfree_)
+            __pfree_(eback());
+        else
+            delete [] eback();
+    }
+}
+
+void
+strstreambuf::swap(strstreambuf& __rhs)
+{
+    streambuf::swap(__rhs);
+    _VSTD::swap(__strmode_, __rhs.__strmode_);
+    _VSTD::swap(__alsize_, __rhs.__alsize_);
+    _VSTD::swap(__palloc_, __rhs.__palloc_);
+    _VSTD::swap(__pfree_, __rhs.__pfree_);
+}
+
+void
+strstreambuf::freeze(bool __freezefl)
+{
+    if (__strmode_ & __dynamic)
+    {
+        if (__freezefl)
+            __strmode_ |= __frozen;
+        else
+            __strmode_ &= ~__frozen;
+    }
+}
+
+char*
+strstreambuf::str()
+{
+    if (__strmode_ & __dynamic)
+        __strmode_ |= __frozen;
+    return eback();
+}
+
+int
+strstreambuf::pcount() const
+{
+    return static_cast<int>(pptr() - pbase());
+}
+
+strstreambuf::int_type
+strstreambuf::overflow(int_type __c)
+{
+    if (__c == EOF)
+        return int_type(0);
+    if (pptr() == epptr())
+    {
+        if ((__strmode_ & __dynamic) == 0 || (__strmode_ & __frozen) != 0)
+            return int_type(EOF);
+        size_t old_size = static_cast<size_t> ((epptr() ? epptr() : egptr()) - eback());
+        size_t new_size = max<size_t>(static_cast<size_t>(__alsize_), 2*old_size);
+        if (new_size == 0)
+            new_size = __default_alsize;
+        char* buf = nullptr;
+        if (__palloc_)
+            buf = static_cast<char*>(__palloc_(new_size));
+        else
+            buf = new char[new_size];
+        if (buf == nullptr)
+            return int_type(EOF);
+        if (old_size != 0) {
+            _LIBCPP_ASSERT(eback(), "overflow copying from NULL");
+            memcpy(buf, eback(), static_cast<size_t>(old_size));
+        }
+        ptrdiff_t ninp = gptr()  - eback();
+        ptrdiff_t einp = egptr() - eback();
+        ptrdiff_t nout = pptr()  - pbase();
+        if (__strmode_ & __allocated)
+        {
+            if (__pfree_)
+                __pfree_(eback());
+            else
+                delete [] eback();
+        }
+        setg(buf, buf + ninp, buf + einp);
+        setp(buf + einp, buf + new_size);
+        __pbump(nout);
+        __strmode_ |= __allocated;
+    }
+    *pptr() = static_cast<char>(__c);
+    pbump(1);
+    return int_type(static_cast<unsigned char>(__c));
+}
+
+strstreambuf::int_type
+strstreambuf::pbackfail(int_type __c)
+{
+    if (eback() == gptr())
+        return EOF;
+    if (__c == EOF)
+    {
+        gbump(-1);
+        return int_type(0);
+    }
+    if (__strmode_ & __constant)
+    {
+        if (gptr()[-1] == static_cast<char>(__c))
+        {
+            gbump(-1);
+            return __c;
+        }
+        return EOF;
+    }
+    gbump(-1);
+    *gptr() = static_cast<char>(__c);
+    return __c;
+}
+
+strstreambuf::int_type
+strstreambuf::underflow()
+{
+    if (gptr() == egptr())
+    {
+        if (egptr() >= pptr())
+            return EOF;
+        setg(eback(), gptr(), pptr());
+    }
+    return int_type(static_cast<unsigned char>(*gptr()));
+}
+
+strstreambuf::pos_type
+strstreambuf::seekoff(off_type __off, ios_base::seekdir __way, ios_base::openmode __which)
+{
+    off_type __p(-1);
+    bool pos_in = (__which & ios::in) != 0;
+    bool pos_out = (__which & ios::out) != 0;
+    bool legal = false;
+    switch (__way)
+    {
+    case ios::beg:
+    case ios::end:
+        if (pos_in || pos_out)
+            legal = true;
+        break;
+    case ios::cur:
+        if (pos_in != pos_out)
+            legal = true;
+        break;
+    }
+    if (pos_in && gptr() == nullptr)
+        legal = false;
+    if (pos_out && pptr() == nullptr)
+        legal = false;
+    if (legal)
+    {
+        off_type newoff;
+        char* seekhigh = epptr() ? epptr() : egptr();
+        switch (__way)
+        {
+        case ios::beg:
+            newoff = 0;
+            break;
+        case ios::cur:
+            newoff = (pos_in ? gptr() : pptr()) - eback();
+            break;
+        case ios::end:
+            newoff = seekhigh - eback();
+            break;
+        default:
+            __libcpp_unreachable();
+        }
+        newoff += __off;
+        if (0 <= newoff && newoff <= seekhigh - eback())
+        {
+            char* newpos = eback() + newoff;
+            if (pos_in)
+                setg(eback(), newpos, _VSTD::max(newpos, egptr()));
+            if (pos_out)
+            {
+                // min(pbase, newpos), newpos, epptr()
+                __off = epptr() - newpos;
+                setp(min(pbase(), newpos), epptr());
+                __pbump((epptr() - pbase()) - __off);
+            }
+            __p = newoff;
+        }
+    }
+    return pos_type(__p);
+}
+
+strstreambuf::pos_type
+strstreambuf::seekpos(pos_type __sp, ios_base::openmode __which)
+{
+    off_type __p(-1);
+    bool pos_in = (__which & ios::in) != 0;
+    bool pos_out = (__which & ios::out) != 0;
+    if (pos_in || pos_out)
+    {
+        if (!((pos_in && gptr() == nullptr) || (pos_out && pptr() == nullptr)))
+        {
+            off_type newoff = __sp;
+            char* seekhigh = epptr() ? epptr() : egptr();
+            if (0 <= newoff && newoff <= seekhigh - eback())
+            {
+                char* newpos = eback() + newoff;
+                if (pos_in)
+                    setg(eback(), newpos, _VSTD::max(newpos, egptr()));
+                if (pos_out)
+                {
+                    // min(pbase, newpos), newpos, epptr()
+                    off_type temp = epptr() - newpos;
+                    setp(min(pbase(), newpos), epptr());
+                    __pbump((epptr() - pbase()) - temp);
+                }
+                __p = newoff;
+            }
+        }
+    }
+    return pos_type(__p);
+}
+
+istrstream::~istrstream()
+{
+}
+
+ostrstream::~ostrstream()
+{
+}
+
+strstream::~strstream()
+{
+}
+
+_LIBCPP_END_NAMESPACE_STD
+
+_LIBCPP_POP_MACROS

third_party/libcxx/src/support/ibm/mbsnrtowcs.cpp

@@ -0,0 +1,95 @@
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#include <cstddef> // size_t
+#include <cwchar>  // mbstate_t
+#include <limits.h> // MB_LEN_MAX
+#include <string.h> // wmemcpy
+
+// Returns the number of wide characters found in the multi byte sequence `src`
+// (of `src_size_bytes`), that fit in the buffer `dst` (of `max_dest_chars`
+// elements size). The count returned excludes the null terminator.
+// When `dst` is NULL, no characters are copied to `dst`.
+// Returns (size_t) -1 when an invalid sequence is encountered.
+// Leaves *`src` pointing to the next character to convert or NULL
+// if a null character was converted from *`src`.
+_LIBCPP_FUNC_VIS
+size_t mbsnrtowcs(wchar_t *__restrict dst, const char **__restrict src,
+                   size_t src_size_bytes, size_t max_dest_chars,
+                   mbstate_t *__restrict ps) {
+  const size_t terminated_sequence = static_cast<size_t>(0);
+  const size_t invalid_sequence = static_cast<size_t>(-1);
+  const size_t incomplete_sequence = static_cast<size_t>(-2);
+
+  size_t source_converted;
+  size_t dest_converted;
+  size_t result = 0;
+
+  // If `dst` is null then `max_dest_chars` should be ignored according to the
+  // standard. Setting `max_dest_chars` to a large value has this effect.
+  if (dst == nullptr)
+    max_dest_chars = static_cast<size_t>(-1);
+
+  for (dest_converted = source_converted = 0;
+       source_converted < src_size_bytes && (!dst || dest_converted < max_dest_chars);
+       ++dest_converted, source_converted += result) {
+    // Converts one multi byte character.
+    // If result (char_size) is greater than 0, it's the size in bytes of that character.
+    // If result (char_size) is zero, it indicates that the null character has been found.
+    // Otherwise, it's an error and errno may be set.
+    size_t source_remaining = src_size_bytes - source_converted;
+    size_t dest_remaining = max_dest_chars - dest_converted;
+
+    if (dst == nullptr) {
+      result = mbrtowc(NULL, *src + source_converted, source_remaining, ps);
+    } else if (dest_remaining >= source_remaining) {
+      // dst has enough space to translate in-place.
+      result = mbrtowc(dst + dest_converted, *src + source_converted, source_remaining, ps);
+    } else {
+      /*
+      * dst may not have enough space, so use a temporary buffer.
+      *
+      * We need to save a copy of the conversion state
+      * here so we can restore it if the multibyte
+      * character is too long for the buffer.
+      */
+      wchar_t buff[MB_LEN_MAX];
+      mbstate_t mbstate_tmp;
+
+      if (ps != nullptr)
+        mbstate_tmp = *ps;
+      result = mbrtowc(buff, *src + source_converted, source_remaining, ps);
+
+      if (result > dest_remaining) {
+        // Multi-byte sequence for character won't fit.
+        if (ps != nullptr)
+          *ps = mbstate_tmp;
+        break;
+      } else {
+        // The buffer was used, so we need copy the translation to dst.
+        wmemcpy(dst, buff, result);
+      }
+    }
+
+    // Don't do anything to change errno from here on.
+    if (result == invalid_sequence || result == terminated_sequence || result == incomplete_sequence) {
+      break;
+    }
+  }
+
+  if (dst) {
+    if (result == terminated_sequence)
+      *src = NULL;
+    else
+      *src += source_converted;
+  }
+  if (result == invalid_sequence)
+    return invalid_sequence;
+
+  return dest_converted;
+}

third_party/libcxx/src/support/ibm/wcsnrtombs.cpp

@@ -0,0 +1,93 @@
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#include <cwchar>  // mbstate_t
+#include <limits.h> // MB_LEN_MAX
+#include <stdlib.h> // MB_CUR_MAX, size_t
+#include <string.h> // memcpy
+
+// Converts `max_source_chars` from the wide character buffer pointer to by *`src`,
+// into the multi byte character sequence buffer stored at `dst`, which must be
+// `dst_size_bytes` bytes in size. Returns the number of bytes in the sequence
+// converted from *src, excluding the null terminator.
+// Returns (size_t) -1 if an error occurs and sets errno.
+// If `dst` is NULL, `dst_size_bytes` is ignored and no bytes are copied to `dst`.
+_LIBCPP_FUNC_VIS
+size_t wcsnrtombs(char *__restrict dst, const wchar_t **__restrict src,
+                   size_t max_source_chars, size_t dst_size_bytes,
+                   mbstate_t *__restrict ps) {
+
+  const size_t invalid_wchar = static_cast<size_t>(-1);
+
+  size_t source_converted;
+  size_t dest_converted;
+  size_t result = 0;
+
+  // If `dst` is null then `dst_size_bytes` should be ignored according to the
+  // standard. Setting dst_size_bytes to a large value has this effect.
+  if (dst == nullptr)
+    dst_size_bytes = static_cast<size_t>(-1);
+
+  for (dest_converted = source_converted = 0;
+       source_converted < max_source_chars && (!dst || dest_converted < dst_size_bytes);
+       ++source_converted, dest_converted += result) {
+    wchar_t c = (*src)[source_converted];
+    size_t dest_remaining = dst_size_bytes - dest_converted;
+
+    if (dst == nullptr) {
+      result = wcrtomb(NULL, c, ps);
+    } else if (dest_remaining >= static_cast<size_t>(MB_CUR_MAX)) {
+      // dst has enough space to translate in-place.
+      result = wcrtomb(dst + dest_converted, c, ps);
+    } else {
+      /*
+      * dst may not have enough space, so use a temporary buffer.
+      *
+      * We need to save a copy of the conversion state
+      * here so we can restore it if the multibyte
+      * character is too long for the buffer.
+      */
+      char buff[MB_LEN_MAX];
+      mbstate_t mbstate_tmp;
+
+      if (ps != nullptr)
+        mbstate_tmp = *ps;
+      result = wcrtomb(buff, c, ps);
+
+      if (result > dest_remaining) {
+        // Multi-byte sequence for character won't fit.
+        if (ps != nullptr)
+          *ps = mbstate_tmp;
+        if (result != invalid_wchar)
+          break;
+      } else {
+        // The buffer was used, so we need copy the translation to dst.
+        memcpy(dst, buff, result);
+      }
+    }
+
+    // result (char_size) contains the size of the multi-byte-sequence converted.
+    // Otherwise, result (char_size) is (size_t) -1 and wcrtomb() sets the errno.
+    if (result == invalid_wchar) {
+      if (dst)
+        *src = *src + source_converted;
+      return invalid_wchar;
+    }
+
+    if (c == L'\0') {
+      if (dst)
+        *src = NULL;
+      return dest_converted;
+    }
+  }
+
+  if (dst)
+    *src = *src + source_converted;
+
+  return dest_converted;
+}

third_party/libcxx/src/support/ibm/xlocale_zos.cpp

@@ -0,0 +1,138 @@
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#include <__assert>
+#include <__support/ibm/xlocale.h>
+#include <sstream>
+#include <vector>
+
+#ifdef __cplusplus
+extern "C" {
+#endif // __cplusplus
+
+locale_t newlocale(int category_mask, const char* locale, locale_t base) {
+  // Maintain current locale name(s) to restore later.
+  std::string current_loc_name(setlocale(LC_ALL, 0));
+
+  // Check for errors.
+  if (category_mask == LC_ALL_MASK && setlocale(LC_ALL, locale) == NULL) {
+    errno = EINVAL;
+    return (locale_t)0;
+  } else {
+    for (int _Cat = 0; _Cat <= _LC_MAX; ++_Cat) {
+      if ((_CATMASK(_Cat) & category_mask) != 0 && setlocale(_Cat, locale) == NULL) {
+        setlocale(LC_ALL, current_loc_name.c_str());
+        errno = EINVAL;
+        return (locale_t)0;
+      }
+    }
+  }
+
+  // Create new locale.
+  locale_t newloc = new locale_struct();
+
+  if (base) {
+    if (category_mask != LC_ALL_MASK) {
+      // Copy base when it will not be overwritten.
+      memcpy(newloc, base, sizeof (locale_struct));
+      newloc->category_mask = category_mask | base->category_mask;
+    }
+    delete base;
+  } else {
+    newloc->category_mask = category_mask;
+  }
+
+  if (category_mask & LC_COLLATE_MASK)
+    newloc->lc_collate = locale;
+  if (category_mask & LC_CTYPE_MASK)
+    newloc->lc_ctype = locale;
+  if (category_mask & LC_MONETARY_MASK)
+    newloc->lc_monetary = locale;
+  if (category_mask & LC_NUMERIC_MASK)
+    newloc->lc_numeric = locale;
+  if (category_mask & LC_TIME_MASK)
+    newloc->lc_time = locale;
+  if (category_mask & LC_MESSAGES_MASK)
+    newloc->lc_messages = locale;
+
+  // Restore current locale.
+  setlocale(LC_ALL, current_loc_name.c_str());
+  return (locale_t)newloc;
+}
+
+void freelocale(locale_t locobj) {
+  delete locobj;
+}
+
+locale_t uselocale(locale_t newloc) {
+  // Maintain current locale name(s).
+  std::string current_loc_name(setlocale(LC_ALL, 0));
+
+  if (newloc) {
+    // Set locales and check for errors.
+    bool is_error =
+      (newloc->category_mask & LC_COLLATE_MASK &&
+        setlocale(LC_COLLATE, newloc->lc_collate.c_str()) == NULL) ||
+      (newloc->category_mask & LC_CTYPE_MASK &&
+        setlocale(LC_CTYPE, newloc->lc_ctype.c_str()) == NULL) ||
+      (newloc->category_mask & LC_MONETARY_MASK &&
+        setlocale(LC_MONETARY, newloc->lc_monetary.c_str()) == NULL) ||
+      (newloc->category_mask & LC_NUMERIC_MASK &&
+        setlocale(LC_NUMERIC, newloc->lc_numeric.c_str()) == NULL) ||
+      (newloc->category_mask & LC_TIME_MASK &&
+        setlocale(LC_TIME, newloc->lc_time.c_str()) == NULL) ||
+      (newloc->category_mask & LC_MESSAGES_MASK &&
+        setlocale(LC_MESSAGES, newloc->lc_messages.c_str()) == NULL);
+
+    if (is_error) {
+      setlocale(LC_ALL, current_loc_name.c_str());
+      errno = EINVAL;
+      return (locale_t)0;
+    }
+  }
+
+  // Construct and return previous locale.
+  locale_t previous_loc = new locale_struct();
+
+  // current_loc_name might be a comma-separated locale name list.
+  if (current_loc_name.find(',') != std::string::npos) {
+    // Tokenize locale name list.
+    const char delimiter = ',';
+    std::vector<std::string> tokenized;
+    std::stringstream ss(current_loc_name);
+    std::string s;
+
+    while (std::getline(ss, s, delimiter)) {
+        tokenized.push_back(s);
+    }
+
+    _LIBCPP_ASSERT(tokenized.size() >= _NCAT, "locale-name list is too short");
+
+    previous_loc->lc_collate = tokenized[LC_COLLATE];
+    previous_loc->lc_ctype = tokenized[LC_CTYPE];
+    previous_loc->lc_monetary = tokenized[LC_MONETARY];
+    previous_loc->lc_numeric = tokenized[LC_NUMERIC];
+    previous_loc->lc_time = tokenized[LC_TIME];
+    // Skip LC_TOD.
+    previous_loc->lc_messages = tokenized[LC_MESSAGES];
+  } else {
+    previous_loc->lc_collate = current_loc_name;
+    previous_loc->lc_ctype = current_loc_name;
+    previous_loc->lc_monetary = current_loc_name;
+    previous_loc->lc_numeric = current_loc_name;
+    previous_loc->lc_time = current_loc_name;
+    previous_loc->lc_messages = current_loc_name;
+  }
+
+  previous_loc->category_mask = LC_ALL_MASK;
+  return previous_loc;
+}
+
+#ifdef __cplusplus
+}
+#endif // __cplusplus

third_party/libcxx/src/support/runtime/exception_fallback.ipp

@@ -0,0 +1,158 @@
+// -*- C++ -*-
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#include <cstdio>
+
+namespace std {
+
+static constinit std::terminate_handler  __terminate_handler = nullptr;
+static constinit std::unexpected_handler __unexpected_handler = nullptr;
+
+// libcxxrt provides implementations of these functions itself.
+unexpected_handler
+set_unexpected(unexpected_handler func) noexcept
+{
+  return __libcpp_atomic_exchange(&__unexpected_handler, func);
+}
+
+unexpected_handler
+get_unexpected() noexcept
+{
+  return __libcpp_atomic_load(&__unexpected_handler);
+}
+
+_LIBCPP_NORETURN
+void unexpected()
+{
+    (*get_unexpected())();
+    // unexpected handler should not return
+    terminate();
+}
+
+terminate_handler
+set_terminate(terminate_handler func) noexcept
+{
+  return __libcpp_atomic_exchange(&__terminate_handler, func);
+}
+
+terminate_handler
+get_terminate() noexcept
+{
+  return __libcpp_atomic_load(&__terminate_handler);
+}
+
+_LIBCPP_NORETURN
+void
+terminate() noexcept
+{
+#ifndef _LIBCPP_HAS_NO_EXCEPTIONS
+    try
+    {
+#endif // _LIBCPP_HAS_NO_EXCEPTIONS
+        (*get_terminate())();
+        // handler should not return
+        fprintf(stderr, "terminate_handler unexpectedly returned\n");
+        ::abort();
+#ifndef _LIBCPP_HAS_NO_EXCEPTIONS
+    }
+    catch (...)
+    {
+        // handler should not throw exception
+        fprintf(stderr, "terminate_handler unexpectedly threw an exception\n");
+        ::abort();
+    }
+#endif // _LIBCPP_HAS_NO_EXCEPTIONS
+}
+
+bool uncaught_exception() noexcept { return uncaught_exceptions() > 0; }
+
+int uncaught_exceptions() noexcept
+{
+#warning uncaught_exception not yet implemented
+  fprintf(stderr, "uncaught_exceptions not yet implemented\n");
+  ::abort();
+}
+
+
+exception::~exception() noexcept
+{
+}
+
+const char* exception::what() const noexcept
+{
+  return "std::exception";
+}
+
+bad_exception::~bad_exception() noexcept
+{
+}
+
+const char* bad_exception::what() const noexcept
+{
+  return "std::bad_exception";
+}
+
+
+bad_alloc::bad_alloc() noexcept
+{
+}
+
+bad_alloc::~bad_alloc() noexcept
+{
+}
+
+const char*
+bad_alloc::what() const noexcept
+{
+    return "std::bad_alloc";
+}
+
+bad_array_new_length::bad_array_new_length() noexcept
+{
+}
+
+bad_array_new_length::~bad_array_new_length() noexcept
+{
+}
+
+const char*
+bad_array_new_length::what() const noexcept
+{
+    return "bad_array_new_length";
+}
+
+bad_cast::bad_cast() noexcept
+{
+}
+
+bad_typeid::bad_typeid() noexcept
+{
+}
+
+bad_cast::~bad_cast() noexcept
+{
+}
+
+const char*
+bad_cast::what() const noexcept
+{
+  return "std::bad_cast";
+}
+
+bad_typeid::~bad_typeid() noexcept
+{
+}
+
+const char*
+bad_typeid::what() const noexcept
+{
+  return "std::bad_typeid";
+}
+
+} // namespace std

third_party/libcxx/src/support/runtime/exception_glibcxx.ipp

@@ -0,0 +1,32 @@
+// -*- C++ -*-
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef __GLIBCXX__
+#error header can only be used when targeting libstdc++ or libsupc++
+#endif
+
+namespace std {
+
+bad_alloc::bad_alloc() noexcept
+{
+}
+
+bad_array_new_length::bad_array_new_length() noexcept
+{
+}
+
+bad_cast::bad_cast() noexcept
+{
+}
+
+bad_typeid::bad_typeid() noexcept
+{
+}
+
+} // namespace std

third_party/libcxx/src/support/runtime/exception_libcxxabi.ipp

@@ -0,0 +1,27 @@
+// -*- C++ -*-
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef _LIBCPPABI_VERSION
+#error this header can only be used with libc++abi
+#endif
+
+namespace std {
+
+bool uncaught_exception() noexcept { return uncaught_exceptions() > 0; }
+
+int uncaught_exceptions() noexcept
+{
+# if _LIBCPPABI_VERSION > 1001
+    return __cxa_uncaught_exceptions();
+# else
+    return __cxa_uncaught_exception() ? 1 : 0;
+# endif
+}
+
+} // namespace std

third_party/libcxx/src/support/runtime/exception_libcxxrt.ipp

@@ -0,0 +1,25 @@
+// -*- C++ -*-
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LIBCXXRT
+#error this header may only be used when targeting libcxxrt
+#endif
+
+namespace std {
+
+bad_exception::~bad_exception() noexcept
+{
+}
+
+const char* bad_exception::what() const noexcept
+{
+  return "std::bad_exception";
+}
+
+} // namespace std

third_party/libcxx/src/support/runtime/exception_msvc.ipp

@@ -0,0 +1,163 @@
+// -*- C++ -*-
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef _LIBCPP_ABI_MICROSOFT
+#error this header can only be used when targeting the MSVC ABI
+#endif
+
+#include <stdio.h>
+#include <stdlib.h>
+
+extern "C" {
+typedef void (__cdecl* terminate_handler)();
+_LIBCPP_CRT_FUNC terminate_handler __cdecl set_terminate(
+    terminate_handler _NewTerminateHandler) throw();
+_LIBCPP_CRT_FUNC terminate_handler __cdecl _get_terminate();
+
+typedef void (__cdecl* unexpected_handler)();
+unexpected_handler __cdecl set_unexpected(
+    unexpected_handler _NewUnexpectedHandler) throw();
+unexpected_handler __cdecl _get_unexpected();
+
+int __cdecl __uncaught_exceptions();
+}
+
+namespace std {
+
+unexpected_handler
+set_unexpected(unexpected_handler func) noexcept {
+  return ::set_unexpected(func);
+}
+
+unexpected_handler get_unexpected() noexcept {
+  return ::_get_unexpected();
+}
+
+_LIBCPP_NORETURN
+void unexpected() {
+    (*get_unexpected())();
+    // unexpected handler should not return
+    terminate();
+}
+
+terminate_handler set_terminate(terminate_handler func) noexcept {
+  return ::set_terminate(func);
+}
+
+terminate_handler get_terminate() noexcept {
+  return ::_get_terminate();
+}
+
+_LIBCPP_NORETURN
+void terminate() noexcept
+{
+#ifndef _LIBCPP_HAS_NO_EXCEPTIONS
+    try
+    {
+#endif // _LIBCPP_HAS_NO_EXCEPTIONS
+        (*get_terminate())();
+        // handler should not return
+        fprintf(stderr, "terminate_handler unexpectedly returned\n");
+        ::abort();
+#ifndef _LIBCPP_HAS_NO_EXCEPTIONS
+    }
+    catch (...)
+    {
+        // handler should not throw exception
+        fprintf(stderr, "terminate_handler unexpectedly threw an exception\n");
+        ::abort();
+    }
+#endif // _LIBCPP_HAS_NO_EXCEPTIONS
+}
+
+bool uncaught_exception() noexcept { return uncaught_exceptions() > 0; }
+
+int uncaught_exceptions() noexcept {
+    return __uncaught_exceptions();
+}
+
+#if !defined(_LIBCPP_ABI_VCRUNTIME)
+bad_cast::bad_cast() noexcept
+{
+}
+
+bad_cast::~bad_cast() noexcept
+{
+}
+
+const char *
+bad_cast::what() const noexcept
+{
+  return "std::bad_cast";
+}
+
+bad_typeid::bad_typeid() noexcept
+{
+}
+
+bad_typeid::~bad_typeid() noexcept
+{
+}
+
+const char *
+bad_typeid::what() const noexcept
+{
+  return "std::bad_typeid";
+}
+
+exception::~exception() noexcept
+{
+}
+
+const char* exception::what() const noexcept
+{
+  return "std::exception";
+}
+
+
+bad_exception::~bad_exception() noexcept
+{
+}
+
+const char* bad_exception::what() const noexcept
+{
+  return "std::bad_exception";
+}
+
+
+bad_alloc::bad_alloc() noexcept
+{
+}
+
+bad_alloc::~bad_alloc() noexcept
+{
+}
+
+const char*
+bad_alloc::what() const noexcept
+{
+    return "std::bad_alloc";
+}
+
+bad_array_new_length::bad_array_new_length() noexcept
+{
+}
+
+bad_array_new_length::~bad_array_new_length() noexcept
+{
+}
+
+const char*
+bad_array_new_length::what() const noexcept
+{
+    return "bad_array_new_length";
+}
+#endif // !_LIBCPP_ABI_VCRUNTIME
+
+} // namespace std

third_party/libcxx/src/support/runtime/exception_pointer_cxxabi.ipp

@@ -0,0 +1,73 @@
+// -*- C++ -*-
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef HAVE_DEPENDENT_EH_ABI
+#error this header may only be used with libc++abi or libcxxrt
+#endif
+
+namespace std {
+
+exception_ptr::~exception_ptr() noexcept {
+  __cxa_decrement_exception_refcount(__ptr_);
+}
+
+exception_ptr::exception_ptr(const exception_ptr& other) noexcept
+    : __ptr_(other.__ptr_)
+{
+    __cxa_increment_exception_refcount(__ptr_);
+}
+
+exception_ptr& exception_ptr::operator=(const exception_ptr& other) noexcept
+{
+    if (__ptr_ != other.__ptr_)
+    {
+        __cxa_increment_exception_refcount(other.__ptr_);
+        __cxa_decrement_exception_refcount(__ptr_);
+        __ptr_ = other.__ptr_;
+    }
+    return *this;
+}
+
+nested_exception::nested_exception() noexcept
+    : __ptr_(current_exception())
+{
+}
+
+nested_exception::~nested_exception() noexcept
+{
+}
+
+_LIBCPP_NORETURN
+void
+nested_exception::rethrow_nested() const
+{
+    if (__ptr_ == nullptr)
+        terminate();
+    rethrow_exception(__ptr_);
+}
+
+exception_ptr current_exception() noexcept
+{
+    // be nicer if there was a constructor that took a ptr, then
+    // this whole function would be just:
+    //    return exception_ptr(__cxa_current_primary_exception());
+    exception_ptr ptr;
+    ptr.__ptr_ = __cxa_current_primary_exception();
+    return ptr;
+}
+
+_LIBCPP_NORETURN
+void rethrow_exception(exception_ptr p)
+{
+    __cxa_rethrow_primary_exception(p.__ptr_);
+    // if p.__ptr_ is NULL, above returns so we terminate
+    terminate();
+}
+
+} // namespace std

third_party/libcxx/src/support/runtime/exception_pointer_glibcxx.ipp

@@ -0,0 +1,77 @@
+// -*- C++ -*-
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+// libsupc++ does not implement the dependent EH ABI and the functionality
+// it uses to implement std::exception_ptr (which it declares as an alias of
+// std::__exception_ptr::exception_ptr) is not directly exported to clients. So
+// we have little choice but to hijack std::__exception_ptr::exception_ptr's
+// (which fortunately has the same layout as our std::exception_ptr) copy
+// constructor, assignment operator and destructor (which are part of its
+// stable ABI), and its rethrow_exception(std::__exception_ptr::exception_ptr)
+// function.
+
+namespace std {
+
+namespace __exception_ptr
+{
+
+struct exception_ptr
+{
+    void* __ptr_;
+
+    exception_ptr(const exception_ptr&) noexcept;
+    exception_ptr& operator=(const exception_ptr&) noexcept;
+    ~exception_ptr() noexcept;
+};
+
+}
+
+_LIBCPP_NORETURN void rethrow_exception(__exception_ptr::exception_ptr);
+
+exception_ptr::~exception_ptr() noexcept
+{
+    reinterpret_cast<__exception_ptr::exception_ptr*>(this)->~exception_ptr();
+}
+
+exception_ptr::exception_ptr(const exception_ptr& other) noexcept
+    : __ptr_(other.__ptr_)
+{
+    new (reinterpret_cast<void*>(this)) __exception_ptr::exception_ptr(
+        reinterpret_cast<const __exception_ptr::exception_ptr&>(other));
+}
+
+exception_ptr& exception_ptr::operator=(const exception_ptr& other) noexcept
+{
+    *reinterpret_cast<__exception_ptr::exception_ptr*>(this) =
+        reinterpret_cast<const __exception_ptr::exception_ptr&>(other);
+    return *this;
+}
+
+nested_exception::nested_exception() noexcept
+    : __ptr_(current_exception())
+{
+}
+
+
+_LIBCPP_NORETURN
+void
+nested_exception::rethrow_nested() const
+{
+    if (__ptr_ == nullptr)
+        terminate();
+    rethrow_exception(__ptr_);
+}
+
+_LIBCPP_NORETURN
+void rethrow_exception(exception_ptr p)
+{
+    rethrow_exception(reinterpret_cast<__exception_ptr::exception_ptr&>(p));
+}
+
+} // namespace std

third_party/libcxx/src/support/runtime/exception_pointer_msvc.ipp

@@ -0,0 +1,86 @@
+// -*- C++ -*-
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#include <stdio.h>
+#include <stdlib.h>
+
+_LIBCPP_CRT_FUNC void __cdecl __ExceptionPtrCreate(void*);
+_LIBCPP_CRT_FUNC void __cdecl __ExceptionPtrDestroy(void*);
+_LIBCPP_CRT_FUNC void __cdecl __ExceptionPtrCopy(void*, const void*);
+_LIBCPP_CRT_FUNC void __cdecl __ExceptionPtrAssign(void*, const void*);
+_LIBCPP_CRT_FUNC bool __cdecl __ExceptionPtrCompare(const void*, const void*);
+_LIBCPP_CRT_FUNC bool __cdecl __ExceptionPtrToBool(const void*);
+_LIBCPP_CRT_FUNC void __cdecl __ExceptionPtrSwap(void*, void*);
+_LIBCPP_CRT_FUNC void __cdecl __ExceptionPtrCurrentException(void*);
+[[noreturn]] _LIBCPP_CRT_FUNC void __cdecl __ExceptionPtrRethrow(const void*);
+_LIBCPP_CRT_FUNC void __cdecl
+__ExceptionPtrCopyException(void*, const void*, const void*);
+
+namespace std {
+
+exception_ptr::exception_ptr() noexcept { __ExceptionPtrCreate(this); }
+exception_ptr::exception_ptr(nullptr_t) noexcept { __ExceptionPtrCreate(this); }
+
+exception_ptr::exception_ptr(const exception_ptr& __other) noexcept {
+  __ExceptionPtrCopy(this, &__other);
+}
+exception_ptr& exception_ptr::operator=(const exception_ptr& __other) noexcept {
+  __ExceptionPtrAssign(this, &__other);
+  return *this;
+}
+
+exception_ptr& exception_ptr::operator=(nullptr_t) noexcept {
+  exception_ptr dummy;
+  __ExceptionPtrAssign(this, &dummy);
+  return *this;
+}
+
+exception_ptr::~exception_ptr() noexcept { __ExceptionPtrDestroy(this); }
+
+exception_ptr::operator bool() const noexcept {
+  return __ExceptionPtrToBool(this);
+}
+
+bool operator==(const exception_ptr& __x, const exception_ptr& __y) noexcept {
+  return __ExceptionPtrCompare(&__x, &__y);
+}
+
+
+void swap(exception_ptr& lhs, exception_ptr& rhs) noexcept {
+  __ExceptionPtrSwap(&rhs, &lhs);
+}
+
+exception_ptr __copy_exception_ptr(void* __except, const void* __ptr) {
+  exception_ptr __ret = nullptr;
+  if (__ptr)
+    __ExceptionPtrCopyException(&__ret, __except, __ptr);
+  return __ret;
+}
+
+exception_ptr current_exception() noexcept {
+  exception_ptr __ret;
+  __ExceptionPtrCurrentException(&__ret);
+  return __ret;
+}
+
+_LIBCPP_NORETURN
+void rethrow_exception(exception_ptr p) { __ExceptionPtrRethrow(&p); }
+
+nested_exception::nested_exception() noexcept : __ptr_(current_exception()) {}
+
+nested_exception::~nested_exception() noexcept {}
+
+_LIBCPP_NORETURN
+void nested_exception::rethrow_nested() const {
+  if (__ptr_ == nullptr)
+    terminate();
+  rethrow_exception(__ptr_);
+}
+
+} // namespace std

third_party/libcxx/src/support/runtime/exception_pointer_unimplemented.ipp

@@ -0,0 +1,79 @@
+// -*- C++ -*-
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#include <stdio.h>
+#include <stdlib.h>
+
+namespace std {
+
+exception_ptr::~exception_ptr() noexcept
+{
+#  warning exception_ptr not yet implemented
+  fprintf(stderr, "exception_ptr not yet implemented\n");
+  ::abort();
+}
+
+exception_ptr::exception_ptr(const exception_ptr& other) noexcept
+    : __ptr_(other.__ptr_)
+{
+#  warning exception_ptr not yet implemented
+  fprintf(stderr, "exception_ptr not yet implemented\n");
+  ::abort();
+}
+
+exception_ptr& exception_ptr::operator=(const exception_ptr& other) noexcept
+{
+#  warning exception_ptr not yet implemented
+  fprintf(stderr, "exception_ptr not yet implemented\n");
+  ::abort();
+}
+
+nested_exception::nested_exception() noexcept
+    : __ptr_(current_exception())
+{
+}
+
+#if !defined(__GLIBCXX__)
+
+nested_exception::~nested_exception() noexcept
+{
+}
+
+#endif
+
+_LIBCPP_NORETURN
+void
+nested_exception::rethrow_nested() const
+{
+#  warning exception_ptr not yet implemented
+  fprintf(stderr, "exception_ptr not yet implemented\n");
+  ::abort();
+#if 0
+  if (__ptr_ == nullptr)
+      terminate();
+  rethrow_exception(__ptr_);
+#endif // FIXME
+}
+
+exception_ptr current_exception() noexcept
+{
+#  warning exception_ptr not yet implemented
+  fprintf(stderr, "exception_ptr not yet implemented\n");
+  ::abort();
+}
+
+_LIBCPP_NORETURN
+void rethrow_exception(exception_ptr p)
+{
+#  warning exception_ptr not yet implemented
+  fprintf(stderr, "exception_ptr not yet implemented\n");
+  ::abort();
+}
+
+} // namespace std

third_party/libcxx/src/support/runtime/new_handler_fallback.ipp

@@ -0,0 +1,26 @@
+// -*- C++ -*-
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+namespace std {
+
+static constinit std::new_handler __new_handler = nullptr;
+
+new_handler
+set_new_handler(new_handler handler) noexcept
+{
+    return __libcpp_atomic_exchange(&__new_handler, handler);
+}
+
+new_handler
+get_new_handler() noexcept
+{
+    return __libcpp_atomic_load(&__new_handler);
+}
+
+} // namespace std

third_party/libcxx/src/support/runtime/stdexcept_default.ipp

@@ -0,0 +1,64 @@
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#include "third_party/libcxx/src/include/refstring.h"
+
+/* For _LIBCPPABI_VERSION */
+#if !defined(_LIBCPP_BUILDING_HAS_NO_ABI_LIBRARY) &&                           \
+    (defined(LIBCXX_BUILDING_LIBCXXABI) || defined(LIBCXXRT))
+#include <cxxabi.h>
+#endif
+
+static_assert(sizeof(std::__libcpp_refstring) == sizeof(const char*), "");
+
+namespace std // purposefully not using versioning namespace
+{
+
+logic_error::logic_error(const string& msg) : __imp_(msg.c_str()) {}
+
+logic_error::logic_error(const char* msg) : __imp_(msg) {}
+
+logic_error::logic_error(const logic_error& le) noexcept : __imp_(le.__imp_) {}
+
+logic_error& logic_error::operator=(const logic_error& le) noexcept {
+  __imp_ = le.__imp_;
+  return *this;
+}
+
+runtime_error::runtime_error(const string& msg) : __imp_(msg.c_str()) {}
+
+runtime_error::runtime_error(const char* msg) : __imp_(msg) {}
+
+runtime_error::runtime_error(const runtime_error& re) noexcept
+    : __imp_(re.__imp_) {}
+
+runtime_error& runtime_error::operator=(const runtime_error& re) noexcept {
+  __imp_ = re.__imp_;
+  return *this;
+}
+
+#if !defined(_LIBCPPABI_VERSION) && !defined(LIBSTDCXX)
+
+const char* logic_error::what() const noexcept { return __imp_.c_str(); }
+
+const char* runtime_error::what() const noexcept { return __imp_.c_str(); }
+
+logic_error::~logic_error() noexcept {}
+domain_error::~domain_error() noexcept {}
+invalid_argument::~invalid_argument() noexcept {}
+length_error::~length_error() noexcept {}
+out_of_range::~out_of_range() noexcept {}
+
+runtime_error::~runtime_error() noexcept {}
+range_error::~range_error() noexcept {}
+overflow_error::~overflow_error() noexcept {}
+underflow_error::~underflow_error() noexcept {}
+
+#endif
+
+} // namespace std

third_party/libcxx/src/support/runtime/stdexcept_vcruntime.ipp

@@ -0,0 +1,16 @@
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef _LIBCPP_ABI_VCRUNTIME
+#error This file may only be used when deferring to vcruntime
+#endif
+
+namespace std {
+logic_error::logic_error(std::string const& s) : exception(s.c_str()) {}
+runtime_error::runtime_error(std::string const& s) : exception(s.c_str()) {}
+} // namespace std

third_party/libcxx/src/support/win32/locale_win32.cpp

@@ -0,0 +1,143 @@
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#include <locale>
+#include <cstdarg> // va_start, va_end
+#include <memory>
+#include <type_traits>
+
+#include <__locale_dir/locale_base_api/locale_guard.h>
+
+int __libcpp_vasprintf(char **sptr, const char *__restrict fmt, va_list ap);
+
+using std::__libcpp_locale_guard;
+
+// FIXME: base currently unused. Needs manual work to construct the new locale
+locale_t newlocale( int mask, const char * locale, locale_t /*base*/ )
+{
+    return {_create_locale( LC_ALL, locale ), locale};
+}
+
+decltype(MB_CUR_MAX) MB_CUR_MAX_L( locale_t __l )
+{
+#if defined(_LIBCPP_MSVCRT)
+  return ___mb_cur_max_l_func(__l);
+#else
+  __libcpp_locale_guard __current(__l);
+  return MB_CUR_MAX;
+#endif
+}
+
+lconv *localeconv_l( locale_t &loc )
+{
+    __libcpp_locale_guard __current(loc);
+    lconv *lc = localeconv();
+    if (!lc)
+        return lc;
+    return loc.__store_lconv(lc);
+}
+size_t mbrlen_l( const char *__restrict s, size_t n,
+                 mbstate_t *__restrict ps, locale_t loc )
+{
+    __libcpp_locale_guard __current(loc);
+    return mbrlen( s, n, ps );
+}
+size_t mbsrtowcs_l( wchar_t *__restrict dst, const char **__restrict src,
+                    size_t len, mbstate_t *__restrict ps, locale_t loc )
+{
+    __libcpp_locale_guard __current(loc);
+    return mbsrtowcs( dst, src, len, ps );
+}
+size_t wcrtomb_l( char *__restrict s, wchar_t wc, mbstate_t *__restrict ps,
+                  locale_t loc )
+{
+    __libcpp_locale_guard __current(loc);
+    return wcrtomb( s, wc, ps );
+}
+size_t mbrtowc_l( wchar_t *__restrict pwc, const char *__restrict s,
+                  size_t n, mbstate_t *__restrict ps, locale_t loc )
+{
+    __libcpp_locale_guard __current(loc);
+    return mbrtowc( pwc, s, n, ps );
+}
+size_t mbsnrtowcs_l( wchar_t *__restrict dst, const char **__restrict src,
+                     size_t nms, size_t len, mbstate_t *__restrict ps, locale_t loc )
+{
+    __libcpp_locale_guard __current(loc);
+    return mbsnrtowcs( dst, src, nms, len, ps );
+}
+size_t wcsnrtombs_l( char *__restrict dst, const wchar_t **__restrict src,
+                     size_t nwc, size_t len, mbstate_t *__restrict ps, locale_t loc )
+{
+    __libcpp_locale_guard __current(loc);
+    return wcsnrtombs( dst, src, nwc, len, ps );
+}
+wint_t btowc_l( int c, locale_t loc )
+{
+    __libcpp_locale_guard __current(loc);
+    return btowc( c );
+}
+int wctob_l( wint_t c, locale_t loc )
+{
+    __libcpp_locale_guard __current(loc);
+    return wctob( c );
+}
+
+int snprintf_l(char *ret, size_t n, locale_t loc, const char *format, ...)
+{
+    va_list ap;
+    va_start( ap, format );
+#if defined(_LIBCPP_MSVCRT)
+    // FIXME: Remove usage of internal CRT function and globals.
+    int result = __stdio_common_vsprintf(
+        _CRT_INTERNAL_LOCAL_PRINTF_OPTIONS | _CRT_INTERNAL_PRINTF_STANDARD_SNPRINTF_BEHAVIOR,
+        ret, n, format, loc, ap);
+#else
+    __libcpp_locale_guard __current(loc);
+    _LIBCPP_DIAGNOSTIC_PUSH
+    _LIBCPP_CLANG_DIAGNOSTIC_IGNORED("-Wformat-nonliteral")
+    int result = vsnprintf( ret, n, format, ap );
+    _LIBCPP_DIAGNOSTIC_POP
+#endif
+    va_end(ap);
+    return result;
+}
+
+int asprintf_l( char **ret, locale_t loc, const char *format, ... )
+{
+    va_list ap;
+    va_start( ap, format );
+    int result = vasprintf_l( ret, loc, format, ap );
+    va_end(ap);
+    return result;
+}
+int vasprintf_l( char **ret, locale_t loc, const char *format, va_list ap )
+{
+    __libcpp_locale_guard __current(loc);
+    return __libcpp_vasprintf( ret, format, ap );
+}
+
+#if !defined(_LIBCPP_MSVCRT)
+float strtof_l(const char* nptr, char** endptr, locale_t loc) {
+  __libcpp_locale_guard __current(loc);
+  return strtof(nptr, endptr);
+}
+
+long double strtold_l(const char* nptr, char** endptr, locale_t loc) {
+  __libcpp_locale_guard __current(loc);
+  return strtold(nptr, endptr);
+}
+#endif
+
+#if defined(__MINGW32__) && __MSVCRT_VERSION__ < 0x0800
+size_t strftime_l(char *ret, size_t n, const char *format, const struct tm *tm,
+                  locale_t loc) {
+  __libcpp_locale_guard __current(loc);
+  return strftime(ret, n, format, tm);
+}
+#endif

third_party/libcxx/src/support/win32/support.cpp

@@ -0,0 +1,172 @@
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#include <cstdarg> // va_start, va_end
+#include <cstddef> // size_t
+#include <cstdlib> // malloc
+#include <cstdio>  // vsprintf, vsnprintf
+#include <cstring> // strcpy, wcsncpy
+#include <cwchar>  // mbstate_t
+
+
+// Like sprintf, but when return value >= 0 it returns
+// a pointer to a malloc'd string in *sptr.
+// If return >= 0, use free to delete *sptr.
+int __libcpp_vasprintf( char **sptr, const char *__restrict format, va_list ap )
+{
+    *sptr = NULL;
+    // Query the count required.
+    va_list ap_copy;
+    va_copy(ap_copy, ap);
+    _LIBCPP_DIAGNOSTIC_PUSH
+    _LIBCPP_CLANG_DIAGNOSTIC_IGNORED("-Wformat-nonliteral")
+    int count = vsnprintf( NULL, 0, format, ap_copy );
+    _LIBCPP_DIAGNOSTIC_POP
+    va_end(ap_copy);
+    if (count < 0)
+        return count;
+    size_t buffer_size = static_cast<size_t>(count) + 1;
+    char* p = static_cast<char*>(malloc(buffer_size));
+    if ( ! p )
+        return -1;
+    // If we haven't used exactly what was required, something is wrong.
+    // Maybe bug in vsnprintf. Report the error and return.
+    _LIBCPP_DIAGNOSTIC_PUSH
+    _LIBCPP_CLANG_DIAGNOSTIC_IGNORED("-Wformat-nonliteral")
+    if (vsnprintf(p, buffer_size, format, ap) != count) {
+    _LIBCPP_DIAGNOSTIC_POP
+        free(p);
+        return -1;
+    }
+    // All good. This is returning memory to the caller not freeing it.
+    *sptr = p;
+    return count;
+}
+
+// Returns >= 0: the number of wide characters found in the
+// multi byte sequence src (of src_size_bytes), that fit in the buffer dst
+// (of max_dest_chars elements size). The count returned excludes the
+// null terminator. When dst is NULL, no characters are copied
+// and no "out" parameters are updated.
+// Returns (size_t) -1: an incomplete sequence encountered.
+// Leaves *src pointing the next character to convert or NULL
+// if a null character was converted from *src.
+size_t mbsnrtowcs( wchar_t *__restrict dst, const char **__restrict src,
+                   size_t src_size_bytes, size_t max_dest_chars, mbstate_t *__restrict ps )
+{
+    const size_t terminated_sequence = static_cast<size_t>(0);
+    //const size_t invalid_sequence = static_cast<size_t>(-1);
+    const size_t incomplete_sequence = static_cast< size_t>(-2);
+
+    size_t dest_converted = 0;
+    size_t source_converted = 0;
+    size_t source_remaining = src_size_bytes;
+    size_t result = 0;
+    bool have_result = false;
+
+    // If dst is null then max_dest_chars should be ignored according to the
+    // standard.  Setting max_dest_chars to a large value has this effect.
+    if (!dst)
+        max_dest_chars = static_cast<size_t>(-1);
+
+    while ( source_remaining ) {
+        if ( dst && dest_converted >= max_dest_chars )
+            break;
+        // Converts one multi byte character.
+        // if result > 0, it's the size in bytes of that character.
+        // othewise if result is zero it indicates the null character has been found.
+        // otherwise it's an error and errno may be set.
+        size_t char_size = mbrtowc( dst ? dst + dest_converted : NULL, *src + source_converted, source_remaining, ps );
+        // Don't do anything to change errno from here on.
+        if ( char_size > 0 ) {
+            source_remaining -= char_size;
+            source_converted += char_size;
+            ++dest_converted;
+            continue;
+        }
+        result = char_size;
+        have_result = true;
+        break;
+    }
+    if ( dst ) {
+        if ( have_result && result == terminated_sequence )
+            *src = NULL;
+        else
+            *src += source_converted;
+    }
+    if ( have_result && result != terminated_sequence && result != incomplete_sequence )
+        return static_cast<size_t>(-1);
+
+    return dest_converted;
+}
+
+// Converts max_source_chars from the wide character buffer pointer to by *src,
+// into the multi byte character sequence buffer stored at dst which must be
+// dst_size_bytes bytes in size.
+// Returns >= 0: the number of bytes in the sequence
+// converted from *src, excluding the null terminator.
+// Returns size_t(-1) if an error occurs, also sets errno.
+// If dst is NULL dst_size_bytes is ignored and no bytes are copied to dst
+// and no "out" parameters are updated.
+size_t wcsnrtombs( char *__restrict dst, const wchar_t **__restrict src,
+                   size_t max_source_chars, size_t dst_size_bytes, mbstate_t *__restrict ps )
+{
+    //const size_t invalid_sequence = static_cast<size_t>(-1);
+
+    size_t source_converted = 0;
+    size_t dest_converted = 0;
+    size_t dest_remaining = dst_size_bytes;
+    size_t char_size = 0;
+    const errno_t no_error = ( errno_t) 0;
+    errno_t result = ( errno_t ) 0;
+    bool have_result = false;
+    bool terminator_found = false;
+
+    // If dst is null then dst_size_bytes should be ignored according to the
+    // standard.  Setting dest_remaining to a large value has this effect.
+    if (!dst)
+        dest_remaining = static_cast<size_t>(-1);
+
+    while ( source_converted != max_source_chars ) {
+        if ( ! dest_remaining )
+            break;
+        wchar_t c = (*src)[source_converted];
+        if ( dst )
+            result = wcrtomb_s( &char_size, dst + dest_converted, dest_remaining, c, ps);
+        else
+            result = wcrtomb_s( &char_size, NULL, 0, c, ps);
+        // If result is zero there is no error and char_size contains the
+        // size of the multi-byte-sequence converted.
+        // Otherwise result indicates an errno type error.
+        if ( result == no_error ) {
+            if ( c == L'\0' ) {
+                terminator_found = true;
+                break;
+            }
+            ++source_converted;
+            if ( dst )
+                dest_remaining -= char_size;
+            dest_converted += char_size;
+            continue;
+        }
+        have_result = true;
+        break;
+    }
+    if ( dst ) {
+        if ( terminator_found )
+            *src = NULL;
+        else
+            *src = *src + source_converted;
+    }
+    if ( have_result && result != no_error ) {
+        errno = result;
+        return static_cast<size_t>(-1);
+    }
+
+    return dest_converted;
+}

third_party/libcxx/src/support/win32/thread_win32.cpp

@@ -0,0 +1,274 @@
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#include <__threading_support>
+#define NOMINMAX
+#define WIN32_LEAN_AND_MEAN
+#include <windows.h>
+#include <process.h>
+#include <fibersapi.h>
+
+_LIBCPP_BEGIN_NAMESPACE_STD
+
+static_assert(sizeof(__libcpp_mutex_t) == sizeof(SRWLOCK), "");
+static_assert(alignof(__libcpp_mutex_t) == alignof(SRWLOCK), "");
+
+static_assert(sizeof(__libcpp_recursive_mutex_t) == sizeof(CRITICAL_SECTION),
+              "");
+static_assert(alignof(__libcpp_recursive_mutex_t) == alignof(CRITICAL_SECTION),
+              "");
+
+static_assert(sizeof(__libcpp_condvar_t) == sizeof(CONDITION_VARIABLE), "");
+static_assert(alignof(__libcpp_condvar_t) == alignof(CONDITION_VARIABLE), "");
+
+static_assert(sizeof(__libcpp_exec_once_flag) == sizeof(INIT_ONCE), "");
+static_assert(alignof(__libcpp_exec_once_flag) == alignof(INIT_ONCE), "");
+
+static_assert(sizeof(__libcpp_thread_id) == sizeof(DWORD), "");
+static_assert(alignof(__libcpp_thread_id) == alignof(DWORD), "");
+
+static_assert(sizeof(__libcpp_thread_t) == sizeof(HANDLE), "");
+static_assert(alignof(__libcpp_thread_t) == alignof(HANDLE), "");
+
+static_assert(sizeof(__libcpp_tls_key) == sizeof(DWORD), "");
+static_assert(alignof(__libcpp_tls_key) == alignof(DWORD), "");
+
+// Mutex
+int __libcpp_recursive_mutex_init(__libcpp_recursive_mutex_t *__m)
+{
+  InitializeCriticalSection((LPCRITICAL_SECTION)__m);
+  return 0;
+}
+
+int __libcpp_recursive_mutex_lock(__libcpp_recursive_mutex_t *__m)
+{
+  EnterCriticalSection((LPCRITICAL_SECTION)__m);
+  return 0;
+}
+
+bool __libcpp_recursive_mutex_trylock(__libcpp_recursive_mutex_t *__m)
+{
+  return TryEnterCriticalSection((LPCRITICAL_SECTION)__m) != 0;
+}
+
+int __libcpp_recursive_mutex_unlock(__libcpp_recursive_mutex_t *__m)
+{
+  LeaveCriticalSection((LPCRITICAL_SECTION)__m);
+  return 0;
+}
+
+int __libcpp_recursive_mutex_destroy(__libcpp_recursive_mutex_t *__m)
+{
+  DeleteCriticalSection((LPCRITICAL_SECTION)__m);
+  return 0;
+}
+
+int __libcpp_mutex_lock(__libcpp_mutex_t *__m)
+{
+  AcquireSRWLockExclusive((PSRWLOCK)__m);
+  return 0;
+}
+
+bool __libcpp_mutex_trylock(__libcpp_mutex_t *__m)
+{
+  return TryAcquireSRWLockExclusive((PSRWLOCK)__m) != 0;
+}
+
+int __libcpp_mutex_unlock(__libcpp_mutex_t *__m)
+{
+  ReleaseSRWLockExclusive((PSRWLOCK)__m);
+  return 0;
+}
+
+int __libcpp_mutex_destroy(__libcpp_mutex_t *__m)
+{
+  static_cast<void>(__m);
+  return 0;
+}
+
+// Condition Variable
+int __libcpp_condvar_signal(__libcpp_condvar_t *__cv)
+{
+  WakeConditionVariable((PCONDITION_VARIABLE)__cv);
+  return 0;
+}
+
+int __libcpp_condvar_broadcast(__libcpp_condvar_t *__cv)
+{
+  WakeAllConditionVariable((PCONDITION_VARIABLE)__cv);
+  return 0;
+}
+
+int __libcpp_condvar_wait(__libcpp_condvar_t *__cv, __libcpp_mutex_t *__m)
+{
+  SleepConditionVariableSRW((PCONDITION_VARIABLE)__cv, (PSRWLOCK)__m, INFINITE, 0);
+  return 0;
+}
+
+int __libcpp_condvar_timedwait(__libcpp_condvar_t *__cv, __libcpp_mutex_t *__m,
+                               __libcpp_timespec_t *__ts)
+{
+  using namespace _VSTD::chrono;
+
+  auto duration = seconds(__ts->tv_sec) + nanoseconds(__ts->tv_nsec);
+  auto abstime =
+      system_clock::time_point(duration_cast<system_clock::duration>(duration));
+  auto timeout_ms = duration_cast<milliseconds>(abstime - system_clock::now());
+
+  if (!SleepConditionVariableSRW((PCONDITION_VARIABLE)__cv, (PSRWLOCK)__m,
+                                 timeout_ms.count() > 0 ? timeout_ms.count()
+                                                        : 0,
+                                 0))
+    {
+      auto __ec = GetLastError();
+      return __ec == ERROR_TIMEOUT ? ETIMEDOUT : __ec;
+    }
+  return 0;
+}
+
+int __libcpp_condvar_destroy(__libcpp_condvar_t *__cv)
+{
+  static_cast<void>(__cv);
+  return 0;
+}
+
+// Execute Once
+static inline _LIBCPP_INLINE_VISIBILITY BOOL CALLBACK
+__libcpp_init_once_execute_once_thunk(PINIT_ONCE __init_once, PVOID __parameter,
+                                      PVOID *__context)
+{
+  static_cast<void>(__init_once);
+  static_cast<void>(__context);
+
+  void (*init_routine)(void) = reinterpret_cast<void (*)(void)>(__parameter);
+  init_routine();
+  return TRUE;
+}
+
+int __libcpp_execute_once(__libcpp_exec_once_flag *__flag,
+                          void (*__init_routine)(void))
+{
+  if (!InitOnceExecuteOnce((PINIT_ONCE)__flag, __libcpp_init_once_execute_once_thunk,
+                           reinterpret_cast<void *>(__init_routine), NULL))
+    return GetLastError();
+  return 0;
+}
+
+// Thread ID
+bool __libcpp_thread_id_equal(__libcpp_thread_id __lhs,
+                              __libcpp_thread_id __rhs)
+{
+  return __lhs == __rhs;
+}
+
+bool __libcpp_thread_id_less(__libcpp_thread_id __lhs, __libcpp_thread_id __rhs)
+{
+  return __lhs < __rhs;
+}
+
+// Thread
+struct __libcpp_beginthreadex_thunk_data
+{
+  void *(*__func)(void *);
+  void *__arg;
+};
+
+static inline _LIBCPP_INLINE_VISIBILITY unsigned WINAPI
+__libcpp_beginthreadex_thunk(void *__raw_data)
+{
+  auto *__data =
+      static_cast<__libcpp_beginthreadex_thunk_data *>(__raw_data);
+  auto *__func = __data->__func;
+  void *__arg = __data->__arg;
+  delete __data;
+  return static_cast<unsigned>(reinterpret_cast<uintptr_t>(__func(__arg)));
+}
+
+bool __libcpp_thread_isnull(const __libcpp_thread_t *__t) {
+  return *__t == 0;
+}
+
+int __libcpp_thread_create(__libcpp_thread_t *__t, void *(*__func)(void *),
+                           void *__arg)
+{
+  auto *__data = new __libcpp_beginthreadex_thunk_data;
+  __data->__func = __func;
+  __data->__arg = __arg;
+
+  *__t = reinterpret_cast<HANDLE>(_beginthreadex(nullptr, 0,
+                                                 __libcpp_beginthreadex_thunk,
+                                                 __data, 0, nullptr));
+
+  if (*__t)
+    return 0;
+  return GetLastError();
+}
+
+__libcpp_thread_id __libcpp_thread_get_current_id()
+{
+  return GetCurrentThreadId();
+}
+
+__libcpp_thread_id __libcpp_thread_get_id(const __libcpp_thread_t *__t)
+{
+  return GetThreadId(*__t);
+}
+
+int __libcpp_thread_join(__libcpp_thread_t *__t)
+{
+  if (WaitForSingleObjectEx(*__t, INFINITE, FALSE) == WAIT_FAILED)
+    return GetLastError();
+  if (!CloseHandle(*__t))
+    return GetLastError();
+  return 0;
+}
+
+int __libcpp_thread_detach(__libcpp_thread_t *__t)
+{
+  if (!CloseHandle(*__t))
+    return GetLastError();
+  return 0;
+}
+
+void __libcpp_thread_yield()
+{
+  SwitchToThread();
+}
+
+void __libcpp_thread_sleep_for(const chrono::nanoseconds& __ns)
+{
+  // round-up to the nearest millisecond
+  chrono::milliseconds __ms = chrono::ceil<chrono::milliseconds>(__ns);
+  // FIXME(compnerd) this should be an alertable sleep (WFSO or SleepEx)
+  Sleep(__ms.count());
+}
+
+// Thread Local Storage
+int __libcpp_tls_create(__libcpp_tls_key* __key,
+                        void(_LIBCPP_TLS_DESTRUCTOR_CC* __at_exit)(void*))
+{
+  DWORD index = FlsAlloc(__at_exit);
+  if (index == FLS_OUT_OF_INDEXES)
+    return GetLastError();
+  *__key = index;
+  return 0;
+}
+
+void *__libcpp_tls_get(__libcpp_tls_key __key)
+{
+  return FlsGetValue(__key);
+}
+
+int __libcpp_tls_set(__libcpp_tls_key __key, void *__p)
+{
+  if (!FlsSetValue(__key, __p))
+    return GetLastError();
+  return 0;
+}
+
+_LIBCPP_END_NAMESPACE_STD

third_party/libcxx/src/system_error.cpp

@@ -0,0 +1,298 @@
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#include <__config>
+#ifdef _LIBCPP_DEPRECATED_ABI_LEGACY_LIBRARY_DEFINITIONS_FOR_INLINE_FUNCTIONS
+#   define _LIBCPP_ERROR_CATEGORY_DEFINE_LEGACY_INLINE_FUNCTIONS
+#endif
+
+#include <__assert>
+#include <cerrno>
+#include <cstdio>
+#include <cstdlib>
+#include <cstring>
+#include <string>
+#include <string.h>
+#include <system_error>
+
+#include "third_party/libcxx/src/include/config_elast.h"
+
+#if defined(__ANDROID__)
+#include <android/api-level.h>
+#endif
+
+_LIBCPP_BEGIN_NAMESPACE_STD
+
+// class error_category
+
+#if defined(_LIBCPP_ERROR_CATEGORY_DEFINE_LEGACY_INLINE_FUNCTIONS)
+error_category::error_category() noexcept
+{
+}
+#endif
+
+error_category::~error_category() noexcept
+{
+}
+
+error_condition
+error_category::default_error_condition(int ev) const noexcept
+{
+    return error_condition(ev, *this);
+}
+
+bool
+error_category::equivalent(int code, const error_condition& condition) const noexcept
+{
+    return default_error_condition(code) == condition;
+}
+
+bool
+error_category::equivalent(const error_code& code, int condition) const noexcept
+{
+    return *this == code.category() && code.value() == condition;
+}
+
+#if !defined(_LIBCPP_HAS_NO_THREADS)
+namespace {
+
+//  GLIBC also uses 1024 as the maximum buffer size internally.
+constexpr size_t strerror_buff_size = 1024;
+
+string do_strerror_r(int ev);
+
+#if defined(_LIBCPP_MSVCRT_LIKE)
+string do_strerror_r(int ev) {
+  char buffer[strerror_buff_size];
+  if (::strerror_s(buffer, strerror_buff_size, ev) == 0)
+    return string(buffer);
+  std::snprintf(buffer, strerror_buff_size, "unknown error %d", ev);
+  return string(buffer);
+}
+#else
+
+// Only one of the two following functions will be used, depending on
+// the return type of strerror_r:
+
+// For the GNU variant, a char* return value:
+__attribute__((unused)) const char *
+handle_strerror_r_return(char *strerror_return, char *buffer) {
+  // GNU always returns a string pointer in its return value. The
+  // string might point to either the input buffer, or a static
+  // buffer, but we don't care which.
+  return strerror_return;
+}
+
+// For the POSIX variant: an int return value.
+__attribute__((unused)) const char *
+handle_strerror_r_return(int strerror_return, char *buffer) {
+  // The POSIX variant either:
+  // - fills in the provided buffer and returns 0
+  // - returns a positive error value, or
+  // - returns -1 and fills in errno with an error value.
+  if (strerror_return == 0)
+    return buffer;
+
+  // Only handle EINVAL. Other errors abort.
+  int new_errno = strerror_return == -1 ? errno : strerror_return;
+  if (new_errno == EINVAL)
+    return "";
+
+  _LIBCPP_ASSERT(new_errno == ERANGE, "unexpected error from ::strerror_r");
+  // FIXME maybe? 'strerror_buff_size' is likely to exceed the
+  // maximum error size so ERANGE shouldn't be returned.
+  std::abort();
+}
+
+// This function handles both GNU and POSIX variants, dispatching to
+// one of the two above functions.
+string do_strerror_r(int ev) {
+    char buffer[strerror_buff_size];
+    // Preserve errno around the call. (The C++ standard requires that
+    // system_error functions not modify errno).
+    const int old_errno = errno;
+    const char *error_message = handle_strerror_r_return(
+        ::strerror_r(ev, buffer, strerror_buff_size), buffer);
+    // If we didn't get any message, print one now.
+    if (!error_message[0]) {
+      std::snprintf(buffer, strerror_buff_size, "Unknown error %d", ev);
+      error_message = buffer;
+    }
+    errno = old_errno;
+    return string(error_message);
+}
+#endif
+} // end namespace
+#endif
+
+string
+__do_message::message(int ev) const
+{
+#if defined(_LIBCPP_HAS_NO_THREADS)
+    return string(::strerror(ev));
+#else
+    return do_strerror_r(ev);
+#endif
+}
+
+class _LIBCPP_HIDDEN __generic_error_category
+    : public __do_message
+{
+public:
+    virtual const char* name() const noexcept;
+    virtual string message(int ev) const;
+};
+
+const char*
+__generic_error_category::name() const noexcept
+{
+    return "generic";
+}
+
+string
+__generic_error_category::message(int ev) const
+{
+#ifdef _LIBCPP_ELAST
+    if (ev > _LIBCPP_ELAST)
+      return string("unspecified generic_category error");
+#endif // _LIBCPP_ELAST
+    return __do_message::message(ev);
+}
+
+const error_category&
+generic_category() noexcept
+{
+    static __generic_error_category s;
+    return s;
+}
+
+class _LIBCPP_HIDDEN __system_error_category
+    : public __do_message
+{
+public:
+    virtual const char* name() const noexcept;
+    virtual string message(int ev) const;
+    virtual error_condition default_error_condition(int ev) const noexcept;
+};
+
+const char*
+__system_error_category::name() const noexcept
+{
+    return "system";
+}
+
+string
+__system_error_category::message(int ev) const
+{
+#ifdef _LIBCPP_ELAST
+    if (ev > _LIBCPP_ELAST)
+      return string("unspecified system_category error");
+#endif // _LIBCPP_ELAST
+    return __do_message::message(ev);
+}
+
+error_condition
+__system_error_category::default_error_condition(int ev) const noexcept
+{
+#ifdef _LIBCPP_ELAST
+    if (ev > _LIBCPP_ELAST)
+      return error_condition(ev, system_category());
+#endif // _LIBCPP_ELAST
+    return error_condition(ev, generic_category());
+}
+
+const error_category&
+system_category() noexcept
+{
+    static __system_error_category s;
+    return s;
+}
+
+// error_condition
+
+string
+error_condition::message() const
+{
+    return __cat_->message(__val_);
+}
+
+// error_code
+
+string
+error_code::message() const
+{
+    return __cat_->message(__val_);
+}
+
+// system_error
+
+string
+system_error::__init(const error_code& ec, string what_arg)
+{
+    if (ec)
+    {
+        if (!what_arg.empty())
+            what_arg += ": ";
+        what_arg += ec.message();
+    }
+    return what_arg;
+}
+
+system_error::system_error(error_code ec, const string& what_arg)
+    : runtime_error(__init(ec, what_arg)),
+      __ec_(ec)
+{
+}
+
+system_error::system_error(error_code ec, const char* what_arg)
+    : runtime_error(__init(ec, what_arg)),
+      __ec_(ec)
+{
+}
+
+system_error::system_error(error_code ec)
+    : runtime_error(__init(ec, "")),
+      __ec_(ec)
+{
+}
+
+system_error::system_error(int ev, const error_category& ecat, const string& what_arg)
+    : runtime_error(__init(error_code(ev, ecat), what_arg)),
+      __ec_(error_code(ev, ecat))
+{
+}
+
+system_error::system_error(int ev, const error_category& ecat, const char* what_arg)
+    : runtime_error(__init(error_code(ev, ecat), what_arg)),
+      __ec_(error_code(ev, ecat))
+{
+}
+
+system_error::system_error(int ev, const error_category& ecat)
+    : runtime_error(__init(error_code(ev, ecat), "")),
+      __ec_(error_code(ev, ecat))
+{
+}
+
+system_error::~system_error() noexcept
+{
+}
+
+void
+__throw_system_error(int ev, const char* what_arg)
+{
+#ifndef _LIBCPP_HAS_NO_EXCEPTIONS
+    throw system_error(error_code(ev, system_category()), what_arg);
+#else
+    (void)ev;
+    (void)what_arg;
+    _VSTD::abort();
+#endif
+}
+
+_LIBCPP_END_NAMESPACE_STD

third_party/libcxx/src/thread.cpp

@@ -0,0 +1,217 @@
+//===------------------------- thread.cpp----------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#include <__config>
+
+#ifndef _LIBCPP_HAS_NO_THREADS
+
+#include <exception>
+#include <future>
+#include <limits>
+#include <thread>
+#include <vector>
+
+#if __has_include(<unistd.h>)
+# include <unistd.h> // for sysconf
+#endif
+
+#if defined(__NetBSD__)
+#pragma weak pthread_create // Do not create libpthread dependency
+#endif
+
+#if defined(_LIBCPP_WIN32API)
+#include <windows.h>
+#endif
+
+#if defined(__ELF__) && defined(_LIBCPP_LINK_PTHREAD_LIB)
+#pragma comment(lib, "pthread")
+#endif
+
+_LIBCPP_BEGIN_NAMESPACE_STD
+
+thread::~thread()
+{
+    if (!__libcpp_thread_isnull(&__t_))
+        terminate();
+}
+
+void
+thread::join()
+{
+    int ec = EINVAL;
+    if (!__libcpp_thread_isnull(&__t_))
+    {
+        ec = __libcpp_thread_join(&__t_);
+        if (ec == 0)
+            __t_ = _LIBCPP_NULL_THREAD;
+    }
+
+    if (ec)
+        __throw_system_error(ec, "thread::join failed");
+}
+
+void
+thread::detach()
+{
+    int ec = EINVAL;
+    if (!__libcpp_thread_isnull(&__t_))
+    {
+        ec = __libcpp_thread_detach(&__t_);
+        if (ec == 0)
+            __t_ = _LIBCPP_NULL_THREAD;
+    }
+
+    if (ec)
+        __throw_system_error(ec, "thread::detach failed");
+}
+
+unsigned
+thread::hardware_concurrency() noexcept
+{
+#if defined(_SC_NPROCESSORS_ONLN)
+    long result = sysconf(_SC_NPROCESSORS_ONLN);
+    // sysconf returns -1 if the name is invalid, the option does not exist or
+    // does not have a definite limit.
+    // if sysconf returns some other negative number, we have no idea
+    // what is going on. Default to something safe.
+    if (result < 0)
+        return 0;
+    return static_cast<unsigned>(result);
+#elif defined(_LIBCPP_WIN32API)
+    SYSTEM_INFO info;
+    GetSystemInfo(&info);
+    return info.dwNumberOfProcessors;
+#else  // defined(CTL_HW) && defined(HW_NCPU)
+    // TODO: grovel through /proc or check cpuid on x86 and similar
+    // instructions on other architectures.
+#   if defined(_LIBCPP_WARNING)
+        _LIBCPP_WARNING("hardware_concurrency not yet implemented")
+#   else
+#       warning hardware_concurrency not yet implemented
+#   endif
+    return 0;  // Means not computable [thread.thread.static]
+#endif // defined(CTL_HW) && defined(HW_NCPU)
+}
+
+namespace this_thread
+{
+
+void
+sleep_for(const chrono::nanoseconds& ns)
+{
+    if (ns > chrono::nanoseconds::zero())
+    {
+        __libcpp_thread_sleep_for(ns);
+    }
+}
+
+}  // this_thread
+
+__thread_specific_ptr<__thread_struct>&
+__thread_local_data()
+{
+  // Even though __thread_specific_ptr's destructor doesn't actually destroy
+  // anything (see comments there), we can't call it at all because threads may
+  // outlive the static variable and calling its destructor means accessing an
+  // object outside of its lifetime, which is UB.
+  alignas(__thread_specific_ptr<__thread_struct>) static char __b[sizeof(__thread_specific_ptr<__thread_struct>)];
+  static __thread_specific_ptr<__thread_struct>* __p = new (__b) __thread_specific_ptr<__thread_struct>();
+  return *__p;
+}
+
+// __thread_struct_imp
+
+template <class T>
+class _LIBCPP_HIDDEN __hidden_allocator
+{
+public:
+    typedef T  value_type;
+
+    T* allocate(size_t __n)
+        {return static_cast<T*>(::operator new(__n * sizeof(T)));}
+    void deallocate(T* __p, size_t) {::operator delete(static_cast<void*>(__p));}
+
+    size_t max_size() const {return size_t(~0) / sizeof(T);}
+};
+
+class _LIBCPP_HIDDEN __thread_struct_imp
+{
+    typedef vector<__assoc_sub_state*,
+                          __hidden_allocator<__assoc_sub_state*> > _AsyncStates;
+    typedef vector<pair<condition_variable*, mutex*>,
+               __hidden_allocator<pair<condition_variable*, mutex*> > > _Notify;
+
+    _AsyncStates async_states_;
+    _Notify notify_;
+
+    __thread_struct_imp(const __thread_struct_imp&);
+    __thread_struct_imp& operator=(const __thread_struct_imp&);
+public:
+    __thread_struct_imp() {}
+    ~__thread_struct_imp();
+
+    void notify_all_at_thread_exit(condition_variable* cv, mutex* m);
+    void __make_ready_at_thread_exit(__assoc_sub_state* __s);
+};
+
+__thread_struct_imp::~__thread_struct_imp()
+{
+    for (_Notify::iterator i = notify_.begin(), e = notify_.end();
+            i != e; ++i)
+    {
+        i->first->notify_all();
+        i->second->unlock();
+    }
+    for (_AsyncStates::iterator i = async_states_.begin(), e = async_states_.end();
+            i != e; ++i)
+    {
+        (*i)->__make_ready();
+        (*i)->__release_shared();
+    }
+}
+
+void
+__thread_struct_imp::notify_all_at_thread_exit(condition_variable* cv, mutex* m)
+{
+    notify_.push_back(pair<condition_variable*, mutex*>(cv, m));
+}
+
+void
+__thread_struct_imp::__make_ready_at_thread_exit(__assoc_sub_state* __s)
+{
+    async_states_.push_back(__s);
+    __s->__add_shared();
+}
+
+// __thread_struct
+
+__thread_struct::__thread_struct()
+    : __p_(new __thread_struct_imp)
+{
+}
+
+__thread_struct::~__thread_struct()
+{
+    delete __p_;
+}
+
+void
+__thread_struct::notify_all_at_thread_exit(condition_variable* cv, mutex* m)
+{
+    __p_->notify_all_at_thread_exit(cv, m);
+}
+
+void
+__thread_struct::__make_ready_at_thread_exit(__assoc_sub_state* __s)
+{
+    __p_->__make_ready_at_thread_exit(__s);
+}
+
+_LIBCPP_END_NAMESPACE_STD
+
+#endif // !_LIBCPP_HAS_NO_THREADS

third_party/libcxx/src/typeinfo.cpp

@@ -0,0 +1,58 @@
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#include <typeinfo>
+
+#if defined(_LIBCPP_ABI_MICROSOFT) && !defined(_LIBCPP_ABI_VCRUNTIME)
+
+#include <string.h>
+
+int std::type_info::__compare(const type_info &__rhs) const noexcept {
+  if (&__data == &__rhs.__data)
+    return 0;
+  return strcmp(&__data.__decorated_name[1], &__rhs.__data.__decorated_name[1]);
+}
+
+const char *std::type_info::name() const noexcept {
+  // TODO(compnerd) cache demangled &__data.__decorated_name[1]
+  return &__data.__decorated_name[1];
+}
+
+size_t std::type_info::hash_code() const noexcept {
+#if defined(_WIN64)
+  constexpr size_t fnv_offset_basis = 14695981039346656037ull;
+  constexpr size_t fnv_prime = 10995116282110ull;
+#else
+  constexpr size_t fnv_offset_basis = 2166136261ull;
+  constexpr size_t fnv_prime = 16777619ull;
+#endif
+
+  size_t value = fnv_offset_basis;
+  for (const char* c = &__data.__decorated_name[1]; *c; ++c) {
+    value ^= static_cast<size_t>(static_cast<unsigned char>(*c));
+    value *= fnv_prime;
+  }
+
+#if defined(_WIN64)
+  value ^= value >> 32;
+#endif
+
+  return value;
+}
+#endif // _LIBCPP_ABI_MICROSOFT
+
+// FIXME: Remove the _LIBCPP_BUILDING_HAS_NO_ABI_LIBRARY configuration.
+#if (!defined(LIBCXX_BUILDING_LIBCXXABI) &&               \
+     !defined(LIBCXXRT) &&                                \
+     !defined(__GLIBCXX__) &&                             \
+     !defined(_LIBCPP_ABI_VCRUNTIME)) ||                  \
+    defined(_LIBCPP_BUILDING_HAS_NO_ABI_LIBRARY)
+std::type_info::~type_info()
+{
+}
+#endif

third_party/libcxx/src/valarray.cpp

@@ -0,0 +1,57 @@
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#include <valarray>
+
+_LIBCPP_BEGIN_NAMESPACE_STD
+
+// These two symbols are part of the v1 ABI but not part of the >=v2 ABI.
+#if _LIBCPP_ABI_VERSION == 1
+template _LIBCPP_FUNC_VIS valarray<size_t>::valarray(size_t);
+template _LIBCPP_FUNC_VIS valarray<size_t>::~valarray();
+#endif
+
+template void valarray<size_t>::resize(size_t, size_t);
+
+void
+gslice::__init(size_t __start)
+{
+    valarray<size_t> __indices(__size_.size());
+    size_t __k = __size_.size() != 0;
+    for (size_t __i = 0; __i < __size_.size(); ++__i)
+        __k *= __size_[__i];
+    __1d_.resize(__k);
+    if (__1d_.size())
+    {
+        __k = 0;
+        __1d_[__k] = __start;
+        while (true)
+        {
+            size_t __i = __indices.size() - 1;
+            while (true)
+            {
+                if (++__indices[__i] < __size_[__i])
+                {
+                    ++__k;
+                    __1d_[__k] = __1d_[__k-1] + __stride_[__i];
+                    for (size_t __j = __i + 1; __j != __indices.size(); ++__j)
+                        __1d_[__k] -= __stride_[__j] * (__size_[__j] - 1);
+                    break;
+                }
+                else
+                {
+                    if (__i == 0)
+                        return;
+                    __indices[__i--] = 0;
+                }
+            }
+        }
+    }
+}
+
+_LIBCPP_END_NAMESPACE_STD

third_party/libcxx/src/variant.cpp

@@ -0,0 +1,17 @@
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#include <variant>
+
+namespace std {
+
+const char* bad_variant_access::what() const noexcept {
+  return "bad_variant_access";
+}
+
+}  // namespace std

third_party/libcxx/src/vector.cpp

@@ -0,0 +1,34 @@
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#include <vector>
+
+_LIBCPP_BEGIN_NAMESPACE_STD
+
+#ifndef _LIBCPP_ABI_DO_NOT_EXPORT_VECTOR_BASE_COMMON
+
+template <bool>
+struct __vector_base_common;
+
+template <>
+struct __vector_base_common<true> {
+  _LIBCPP_NORETURN _LIBCPP_EXPORTED_FROM_ABI void __throw_length_error() const;
+  _LIBCPP_NORETURN _LIBCPP_EXPORTED_FROM_ABI void __throw_out_of_range() const;
+};
+
+void __vector_base_common<true>::__throw_length_error() const {
+  _VSTD::__throw_length_error("vector");
+}
+
+void __vector_base_common<true>::__throw_out_of_range() const {
+  _VSTD::__throw_out_of_range("vector");
+}
+
+#endif // _LIBCPP_ABI_DO_NOT_EXPORT_VECTOR_BASE_COMMON
+
+_LIBCPP_END_NAMESPACE_STD

third_party/libcxx/src/verbose_abort.cpp

@@ -0,0 +1,77 @@
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#include <__config>
+#include <__verbose_abort>
+#include <cstdarg>
+#include <cstdio>
+#include <cstdlib>
+
+#ifdef __BIONIC__
+#  include <android/api-level.h>
+#  if __ANDROID_API__ >= 21
+#    include <syslog.h>
+extern "C" void android_set_abort_message(const char* msg);
+#  else
+#    include <assert.h>
+#  endif // __ANDROID_API__ >= 21
+#endif   // __BIONIC__
+
+#if defined(__APPLE__) && __has_include(<CrashReporterClient.h>)
+#  include <CrashReporterClient.h>
+#endif
+
+_LIBCPP_BEGIN_NAMESPACE_STD
+
+_LIBCPP_WEAK
+void __libcpp_verbose_abort(char const* format, ...) {
+  // Write message to stderr. We do this before formatting into a
+  // buffer so that we still get some information out if that fails.
+  {
+    va_list list;
+    va_start(list, format);
+    std::vfprintf(stderr, format, list);
+    va_end(list);
+  }
+
+  // Format the arguments into an allocated buffer for CrashReport & friends.
+  // We leak the buffer on purpose, since we're about to abort() anyway.
+  char* buffer; (void)buffer;
+  va_list list;
+  va_start(list, format);
+
+#if defined(__APPLE__) && __has_include(<CrashReporterClient.h>)
+  // Note that we should technically synchronize accesses here (by e.g. taking a lock),
+  // however concretely we're only setting a pointer, so the likelihood of a race here
+  // is low.
+  vasprintf(&buffer, format, list);
+  CRSetCrashLogMessage(buffer);
+#elif defined(__BIONIC__)
+  vasprintf(&buffer, format, list);
+
+#  if __ANDROID_API__ >= 21
+  // Show error in tombstone.
+  android_set_abort_message(buffer);
+
+  // Show error in logcat.
+  openlog("libc++", 0, 0);
+  syslog(LOG_CRIT, "%s", buffer);
+  closelog();
+#  else
+  // The good error reporting wasn't available in Android until L. Since we're
+  // about to abort anyway, just call __assert2, which will log _somewhere_
+  // (tombstone and/or logcat) in older releases.
+  __assert2(__FILE__, __LINE__, __func__, buffer);
+#  endif // __ANDROID_API__ >= 21
+#endif
+  va_end(list);
+
+  std::abort();
+}
+
+_LIBCPP_END_NAMESPACE_STD