Re-enable separation of protobufs for Python 2 and Python 3

Это откат коммита https://a.yandex-team.ru/arcadia/commit/rXXXXXX
И соответственно возврат коммитов https://a.yandex-team.ru/arcadia/commit/rXXXXXX и https://a.yandex-team.ru/arcadia/commit/rXXXXXX

Починка причины отката влилась здесь: https://a.yandex-team.ru/arcadia/commit/rXXXXXX
ae529e54d3ef7992b0e9f152373bc300061c1293

1 files changed, 1057 insertions, 0 deletions

diff --git a/contrib/libs/protobuf_old/src/google/protobuf/repeated_field.h b/contrib/libs/protobuf_old/src/google/protobuf/repeated_field.h
new file mode 100644
index 0000000000..2b7fe6135d
--- /dev/null
+++ b/contrib/libs/protobuf_old/src/google/protobuf/repeated_field.h
@@ -0,0 +1,1057 @@
+// Protocol Buffers - Google's data interchange format
+// Copyright 2008 Google Inc.  All rights reserved.
+// https://developers.google.com/protocol-buffers/
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+// notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+// copyright notice, this list of conditions and the following disclaimer
+// in the documentation and/or other materials provided with the
+// distribution.
+//     * Neither the name of Google Inc. nor the names of its
+// contributors may be used to endorse or promote products derived from
+// this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+// Author: kenton@google.com (Kenton Varda)
+//  Based on original Protocol Buffers design by
+//  Sanjay Ghemawat, Jeff Dean, and others.
+//
+// RepeatedField and RepeatedPtrField are used by generated protocol message
+// classes to manipulate repeated fields.  These classes are very similar to
+// STL's vector, but include a number of optimizations found to be useful
+// specifically in the case of Protocol Buffers.  RepeatedPtrField is
+// particularly different from STL vector as it manages ownership of the
+// pointers that it contains.
+//
+// Typically, clients should not need to access RepeatedField objects directly,
+// but should instead use the accessor functions generated automatically by the
+// protocol compiler.
+//
+// This header covers RepeatedField.
+
+#ifndef GOOGLE_PROTOBUF_REPEATED_FIELD_H__
+#define GOOGLE_PROTOBUF_REPEATED_FIELD_H__
+
+#include <utility>
+#ifdef _MSC_VER
+// This is required for min/max on VS2013 only.
+#include <algorithm>
+#endif
+
+#include <iterator>
+#include <limits>
+#include <string>
+#include <type_traits>
+
+#include <google/protobuf/stubs/logging.h>
+#include <google/protobuf/stubs/common.h>
+#include <google/protobuf/repeated_ptr_field.h>
+#include <google/protobuf/arena.h>
+#include <google/protobuf/message_lite.h>
+#include <google/protobuf/port.h>
+
+
+// Must be included last.
+#include <google/protobuf/port_def.inc>
+
+#ifdef SWIG
+#error "You cannot SWIG proto headers"
+#endif
+
+namespace google {
+namespace protobuf {
+
+class Message;
+
+namespace internal {
+
+// kRepeatedFieldLowerClampLimit is the smallest size that will be allocated
+// when growing a repeated field.
+constexpr int kRepeatedFieldLowerClampLimit = 4;
+
+// kRepeatedFieldUpperClampLimit is the lowest signed integer value that
+// overflows when multiplied by 2 (which is undefined behavior). Sizes above
+// this will clamp to the maximum int value instead of following exponential
+// growth when growing a repeated field.
+constexpr int kRepeatedFieldUpperClampLimit =
+    (std::numeric_limits<int>::max() / 2) + 1;
+
+template <typename Iter>
+inline int CalculateReserve(Iter begin, Iter end, std::forward_iterator_tag) {
+  return static_cast<int>(std::distance(begin, end));
+}
+
+template <typename Iter>
+inline int CalculateReserve(Iter /*begin*/, Iter /*end*/,
+                            std::input_iterator_tag /*unused*/) {
+  return -1;
+}
+
+template <typename Iter>
+inline int CalculateReserve(Iter begin, Iter end) {
+  typedef typename std::iterator_traits<Iter>::iterator_category Category;
+  return CalculateReserve(begin, end, Category());
+}
+
+// Swaps two blocks of memory of size sizeof(T).
+template <typename T>
+inline void SwapBlock(char* p, char* q) {
+  T tmp;
+  memcpy(&tmp, p, sizeof(T));
+  memcpy(p, q, sizeof(T));
+  memcpy(q, &tmp, sizeof(T));
+}
+
+// Swaps two blocks of memory of size kSize:
+//  template <int kSize> void memswap(char* p, char* q);
+
+template <int kSize>
+inline typename std::enable_if<(kSize == 0), void>::type memswap(char*, char*) {
+}
+
+#define PROTO_MEMSWAP_DEF_SIZE(reg_type, max_size)                           \
+  template <int kSize>                                                       \
+  typename std::enable_if<(kSize >= sizeof(reg_type) && kSize < (max_size)), \
+                          void>::type                                        \
+  memswap(char* p, char* q) {                                                \
+    SwapBlock<reg_type>(p, q);                                               \
+    memswap<kSize - sizeof(reg_type)>(p + sizeof(reg_type),                  \
+                                      q + sizeof(reg_type));                 \
+  }
+
+PROTO_MEMSWAP_DEF_SIZE(uint8_t, 2)
+PROTO_MEMSWAP_DEF_SIZE(uint16_t, 4)
+PROTO_MEMSWAP_DEF_SIZE(arc_ui32, 8)
+
+#ifdef __SIZEOF_INT128__
+PROTO_MEMSWAP_DEF_SIZE(arc_ui64, 16)
+PROTO_MEMSWAP_DEF_SIZE(__uint128_t, (1u << 31))
+#else
+PROTO_MEMSWAP_DEF_SIZE(arc_ui64, (1u << 31))
+#endif
+
+#undef PROTO_MEMSWAP_DEF_SIZE
+
+}  // namespace internal
+
+// RepeatedField is used to represent repeated fields of a primitive type (in
+// other words, everything except strings and nested Messages).  Most users will
+// not ever use a RepeatedField directly; they will use the get-by-index,
+// set-by-index, and add accessors that are generated for all repeated fields.
+template <typename Element>
+class RepeatedField {
+  static_assert(
+      alignof(Arena) >= alignof(Element),
+      "We only support types that have an alignment smaller than Arena");
+
+ public:
+  constexpr RepeatedField();
+  explicit RepeatedField(Arena* arena);
+
+  RepeatedField(const RepeatedField& other);
+
+  template <typename Iter,
+            typename = typename std::enable_if<std::is_constructible<
+                Element, decltype(*std::declval<Iter>())>::value>::type>
+  RepeatedField(Iter begin, Iter end);
+
+  ~RepeatedField();
+
+  RepeatedField& operator=(const RepeatedField& other);
+
+  RepeatedField(RepeatedField&& other) noexcept;
+  RepeatedField& operator=(RepeatedField&& other) noexcept;
+
+  bool empty() const;
+  int size() const;
+
+  const Element& Get(int index) const;
+  Element* Mutable(int index);
+
+  const Element& operator[](int index) const { return Get(index); }
+  Element& operator[](int index) { return *Mutable(index); }
+
+  const Element& at(int index) const;
+  Element& at(int index);
+
+  void Set(int index, const Element& value);
+  void Add(const Element& value);
+  // Appends a new element and return a pointer to it.
+  // The new element is uninitialized if |Element| is a POD type.
+  Element* Add();
+  // Append elements in the range [begin, end) after reserving
+  // the appropriate number of elements.
+  template <typename Iter>
+  void Add(Iter begin, Iter end);
+
+  // Remove the last element in the array.
+  void RemoveLast();
+
+  // Extract elements with indices in "[start .. start+num-1]".
+  // Copy them into "elements[0 .. num-1]" if "elements" is not nullptr.
+  // Caution: implementation also moves elements with indices [start+num ..].
+  // Calling this routine inside a loop can cause quadratic behavior.
+  void ExtractSubrange(int start, int num, Element* elements);
+
+  PROTOBUF_ATTRIBUTE_REINITIALIZES void Clear();
+  void MergeFrom(const RepeatedField& other);
+  PROTOBUF_ATTRIBUTE_REINITIALIZES void CopyFrom(const RepeatedField& other);
+
+  // Replaces the contents with RepeatedField(begin, end).
+  template <typename Iter>
+  PROTOBUF_ATTRIBUTE_REINITIALIZES void Assign(Iter begin, Iter end);
+
+  // Reserve space to expand the field to at least the given size.  If the
+  // array is grown, it will always be at least doubled in size.
+  void Reserve(int new_size);
+
+  // Resize the RepeatedField to a new, smaller size.  This is O(1).
+  void Truncate(int new_size);
+
+  void AddAlreadyReserved(const Element& value);
+  // Appends a new element and return a pointer to it.
+  // The new element is uninitialized if |Element| is a POD type.
+  // Should be called only if Capacity() > Size().
+  Element* AddAlreadyReserved();
+  Element* AddNAlreadyReserved(int elements);
+  int Capacity() const;
+
+  // Like STL resize.  Uses value to fill appended elements.
+  // Like Truncate() if new_size <= size(), otherwise this is
+  // O(new_size - size()).
+  void Resize(int new_size, const Element& value);
+
+  // Gets the underlying array.  This pointer is possibly invalidated by
+  // any add or remove operation.
+  Element* mutable_data();
+  const Element* data() const;
+
+  // Swap entire contents with "other". If they are separate arenas then, copies
+  // data between each other.
+  void Swap(RepeatedField* other);
+
+  // Swap entire contents with "other". Should be called only if the caller can
+  // guarantee that both repeated fields are on the same arena or are on the
+  // heap. Swapping between different arenas is disallowed and caught by a
+  // GOOGLE_DCHECK (see API docs for details).
+  void UnsafeArenaSwap(RepeatedField* other);
+
+  // Swap two elements.
+  void SwapElements(int index1, int index2);
+
+  // STL-like iterator support
+  typedef Element* iterator;
+  typedef const Element* const_iterator;
+  typedef Element value_type;
+  typedef value_type& reference;
+  typedef const value_type& const_reference;
+  typedef value_type* pointer;
+  typedef const value_type* const_pointer;
+  typedef int size_type;
+  typedef ptrdiff_t difference_type;
+
+  iterator begin();
+  const_iterator begin() const;
+  const_iterator cbegin() const;
+  iterator end();
+  const_iterator end() const;
+  const_iterator cend() const;
+
+  // Reverse iterator support
+  typedef std::reverse_iterator<const_iterator> const_reverse_iterator;
+  typedef std::reverse_iterator<iterator> reverse_iterator;
+  reverse_iterator rbegin() { return reverse_iterator(end()); }
+  const_reverse_iterator rbegin() const {
+    return const_reverse_iterator(end());
+  }
+  reverse_iterator rend() { return reverse_iterator(begin()); }
+  const_reverse_iterator rend() const {
+    return const_reverse_iterator(begin());
+  }
+
+  // Returns the number of bytes used by the repeated field, excluding
+  // sizeof(*this)
+  size_t SpaceUsedExcludingSelfLong() const;
+
+  int SpaceUsedExcludingSelf() const {
+    return internal::ToIntSize(SpaceUsedExcludingSelfLong());
+  }
+
+  // Removes the element referenced by position.
+  //
+  // Returns an iterator to the element immediately following the removed
+  // element.
+  //
+  // Invalidates all iterators at or after the removed element, including end().
+  iterator erase(const_iterator position);
+
+  // Removes the elements in the range [first, last).
+  //
+  // Returns an iterator to the element immediately following the removed range.
+  //
+  // Invalidates all iterators at or after the removed range, including end().
+  iterator erase(const_iterator first, const_iterator last);
+
+  // Get the Arena on which this RepeatedField stores its elements.
+  inline Arena* GetArena() const {
+    return (total_size_ == 0) ? static_cast<Arena*>(arena_or_elements_)
+                              : rep()->arena;
+  }
+
+  // For internal use only.
+  //
+  // This is public due to it being called by generated code.
+  inline void InternalSwap(RepeatedField* other);
+
+ private:
+  static constexpr int kInitialSize = 0;
+  // A note on the representation here (see also comment below for
+  // RepeatedPtrFieldBase's struct Rep):
+  //
+  // We maintain the same sizeof(RepeatedField) as before we added arena support
+  // so that we do not degrade performance by bloating memory usage. Directly
+  // adding an arena_ element to RepeatedField is quite costly. By using
+  // indirection in this way, we keep the same size when the RepeatedField is
+  // empty (common case), and add only an 8-byte header to the elements array
+  // when non-empty. We make sure to place the size fields directly in the
+  // RepeatedField class to avoid costly cache misses due to the indirection.
+  int current_size_;
+  int total_size_;
+  struct Rep {
+    Arena* arena;
+    // Here we declare a huge array as a way of approximating C's "flexible
+    // array member" feature without relying on undefined behavior.
+    Element elements[(std::numeric_limits<int>::max() - 2 * sizeof(Arena*)) /
+                     sizeof(Element)];
+  };
+  static constexpr size_t kRepHeaderSize = offsetof(Rep, elements);
+
+  // If total_size_ == 0 this points to an Arena otherwise it points to the
+  // elements member of a Rep struct. Using this invariant allows the storage of
+  // the arena pointer without an extra allocation in the constructor.
+  void* arena_or_elements_;
+
+  // Return pointer to elements array.
+  // pre-condition: the array must have been allocated.
+  Element* elements() const {
+    GOOGLE_DCHECK_GT(total_size_, 0);
+    // Because of above pre-condition this cast is safe.
+    return unsafe_elements();
+  }
+
+  // Return pointer to elements array if it exists otherwise either null or
+  // a invalid pointer is returned. This only happens for empty repeated fields,
+  // where you can't dereference this pointer anyway (it's empty).
+  Element* unsafe_elements() const {
+    return static_cast<Element*>(arena_or_elements_);
+  }
+
+  // Return pointer to the Rep struct.
+  // pre-condition: the Rep must have been allocated, ie elements() is safe.
+  Rep* rep() const {
+    char* addr = reinterpret_cast<char*>(elements()) - offsetof(Rep, elements);
+    return reinterpret_cast<Rep*>(addr);
+  }
+
+  friend class Arena;
+  typedef void InternalArenaConstructable_;
+
+  // Move the contents of |from| into |to|, possibly clobbering |from| in the
+  // process.  For primitive types this is just a memcpy(), but it could be
+  // specialized for non-primitive types to, say, swap each element instead.
+  void MoveArray(Element* to, Element* from, int size);
+
+  // Copy the elements of |from| into |to|.
+  void CopyArray(Element* to, const Element* from, int size);
+
+  // Internal helper to delete all elements and deallocate the storage.
+  void InternalDeallocate(Rep* rep, int size) {
+    if (rep != nullptr) {
+      Element* e = &rep->elements[0];
+      if (!std::is_trivial<Element>::value) {
+        Element* limit = &rep->elements[size];
+        for (; e < limit; e++) {
+          e->~Element();
+        }
+      }
+      if (rep->arena == nullptr) {
+#if defined(__GXX_DELETE_WITH_SIZE__) || defined(__cpp_sized_deallocation)
+        const size_t bytes = size * sizeof(*e) + kRepHeaderSize;
+        ::operator delete(static_cast<void*>(rep), bytes);
+#else
+        ::operator delete(static_cast<void*>(rep));
+#endif
+      }
+    }
+  }
+
+  // This class is a performance wrapper around RepeatedField::Add(const T&)
+  // function. In general unless a RepeatedField is a local stack variable LLVM
+  // has a hard time optimizing Add. The machine code tends to be
+  // loop:
+  // mov %size, dword ptr [%repeated_field]       // load
+  // cmp %size, dword ptr [%repeated_field + 4]
+  // jae fallback
+  // mov %buffer, qword ptr [%repeated_field + 8]
+  // mov dword [%buffer + %size * 4], %value
+  // inc %size                                    // increment
+  // mov dword ptr [%repeated_field], %size       // store
+  // jmp loop
+  //
+  // This puts a load/store in each iteration of the important loop variable
+  // size. It's a pretty bad compile that happens even in simple cases, but
+  // largely the presence of the fallback path disturbs the compilers mem-to-reg
+  // analysis.
+  //
+  // This class takes ownership of a repeated field for the duration of it's
+  // lifetime. The repeated field should not be accessed during this time, ie.
+  // only access through this class is allowed. This class should always be a
+  // function local stack variable. Intended use
+  //
+  // void AddSequence(const int* begin, const int* end, RepeatedField<int>* out)
+  // {
+  //   RepeatedFieldAdder<int> adder(out);  // Take ownership of out
+  //   for (auto it = begin; it != end; ++it) {
+  //     adder.Add(*it);
+  //   }
+  // }
+  //
+  // Typically due to the fact adder is a local stack variable. The compiler
+  // will be successful in mem-to-reg transformation and the machine code will
+  // be loop: cmp %size, %capacity jae fallback mov dword ptr [%buffer + %size *
+  // 4], %val inc %size jmp loop
+  //
+  // The first version executes at 7 cycles per iteration while the second
+  // version near 1 or 2 cycles.
+  template <int = 0, bool = std::is_trivial<Element>::value>
+  class FastAdderImpl {
+   public:
+    explicit FastAdderImpl(RepeatedField* rf) : repeated_field_(rf) {
+      index_ = repeated_field_->current_size_;
+      capacity_ = repeated_field_->total_size_;
+      buffer_ = repeated_field_->unsafe_elements();
+    }
+    ~FastAdderImpl() { repeated_field_->current_size_ = index_; }
+
+    void Add(Element val) {
+      if (index_ == capacity_) {
+        repeated_field_->current_size_ = index_;
+        repeated_field_->Reserve(index_ + 1);
+        capacity_ = repeated_field_->total_size_;
+        buffer_ = repeated_field_->unsafe_elements();
+      }
+      buffer_[index_++] = val;
+    }
+
+   private:
+    RepeatedField* repeated_field_;
+    int index_;
+    int capacity_;
+    Element* buffer_;
+
+    GOOGLE_DISALLOW_EVIL_CONSTRUCTORS(FastAdderImpl);
+  };
+
+  // FastAdder is a wrapper for adding fields. The specialization above handles
+  // POD types more efficiently than RepeatedField.
+  template <int I>
+  class FastAdderImpl<I, false> {
+   public:
+    explicit FastAdderImpl(RepeatedField* rf) : repeated_field_(rf) {}
+    void Add(const Element& val) { repeated_field_->Add(val); }
+
+   private:
+    RepeatedField* repeated_field_;
+    GOOGLE_DISALLOW_EVIL_CONSTRUCTORS(FastAdderImpl);
+  };
+
+  using FastAdder = FastAdderImpl<>;
+
+  friend class TestRepeatedFieldHelper;
+  friend class ::google::protobuf::internal::ParseContext;
+};
+
+namespace internal {
+
+// This is a helper template to copy an array of elements efficiently when they
+// have a trivial copy constructor, and correctly otherwise. This really
+// shouldn't be necessary, but our compiler doesn't optimize std::copy very
+// effectively.
+template <typename Element,
+          bool HasTrivialCopy = std::is_trivial<Element>::value>
+struct ElementCopier {
+  void operator()(Element* to, const Element* from, int array_size);
+};
+
+}  // namespace internal
+
+// implementation ====================================================
+
+template <typename Element>
+constexpr RepeatedField<Element>::RepeatedField()
+    : current_size_(0), total_size_(0), arena_or_elements_(nullptr) {}
+
+template <typename Element>
+inline RepeatedField<Element>::RepeatedField(Arena* arena)
+    : current_size_(0), total_size_(0), arena_or_elements_(arena) {}
+
+template <typename Element>
+inline RepeatedField<Element>::RepeatedField(const RepeatedField& other)
+    : current_size_(0), total_size_(0), arena_or_elements_(nullptr) {
+  if (other.current_size_ != 0) {
+    Reserve(other.size());
+    AddNAlreadyReserved(other.size());
+    CopyArray(Mutable(0), &other.Get(0), other.size());
+  }
+}
+
+template <typename Element>
+template <typename Iter, typename>
+RepeatedField<Element>::RepeatedField(Iter begin, Iter end)
+    : current_size_(0), total_size_(0), arena_or_elements_(nullptr) {
+  Add(begin, end);
+}
+
+template <typename Element>
+RepeatedField<Element>::~RepeatedField() {
+#ifndef NDEBUG
+  // Try to trigger segfault / asan failure in non-opt builds. If arena_
+  // lifetime has ended before the destructor.
+  auto arena = GetArena();
+  if (arena) (void)arena->SpaceAllocated();
+#endif
+  if (total_size_ > 0) {
+    InternalDeallocate(rep(), total_size_);
+  }
+}
+
+template <typename Element>
+inline RepeatedField<Element>& RepeatedField<Element>::operator=(
+    const RepeatedField& other) {
+  if (this != &other) CopyFrom(other);
+  return *this;
+}
+
+template <typename Element>
+inline RepeatedField<Element>::RepeatedField(RepeatedField&& other) noexcept
+    : RepeatedField() {
+#ifdef PROTOBUF_FORCE_COPY_IN_MOVE
+  CopyFrom(other);
+#else   // PROTOBUF_FORCE_COPY_IN_MOVE
+  // We don't just call Swap(&other) here because it would perform 3 copies if
+  // other is on an arena. This field can't be on an arena because arena
+  // construction always uses the Arena* accepting constructor.
+  if (other.GetArena()) {
+    CopyFrom(other);
+  } else {
+    InternalSwap(&other);
+  }
+#endif  // !PROTOBUF_FORCE_COPY_IN_MOVE
+}
+
+template <typename Element>
+inline RepeatedField<Element>& RepeatedField<Element>::operator=(
+    RepeatedField&& other) noexcept {
+  // We don't just call Swap(&other) here because it would perform 3 copies if
+  // the two fields are on different arenas.
+  if (this != &other) {
+    if (GetArena() != other.GetArena()
+#ifdef PROTOBUF_FORCE_COPY_IN_MOVE
+        || GetArena() == nullptr
+#endif  // !PROTOBUF_FORCE_COPY_IN_MOVE
+    ) {
+      CopyFrom(other);
+    } else {
+      InternalSwap(&other);
+    }
+  }
+  return *this;
+}
+
+template <typename Element>
+inline bool RepeatedField<Element>::empty() const {
+  return current_size_ == 0;
+}
+
+template <typename Element>
+inline int RepeatedField<Element>::size() const {
+  return current_size_;
+}
+
+template <typename Element>
+inline int RepeatedField<Element>::Capacity() const {
+  return total_size_;
+}
+
+template <typename Element>
+inline void RepeatedField<Element>::AddAlreadyReserved(const Element& value) {
+  GOOGLE_DCHECK_LT(current_size_, total_size_);
+  elements()[current_size_++] = value;
+}
+
+template <typename Element>
+inline Element* RepeatedField<Element>::AddAlreadyReserved() {
+  GOOGLE_DCHECK_LT(current_size_, total_size_);
+  return &elements()[current_size_++];
+}
+
+template <typename Element>
+inline Element* RepeatedField<Element>::AddNAlreadyReserved(int n) {
+  GOOGLE_DCHECK_GE(total_size_ - current_size_, n)
+      << total_size_ << ", " << current_size_;
+  // Warning: sometimes people call this when n == 0 and total_size_ == 0. In
+  // this case the return pointer points to a zero size array (n == 0). Hence
+  // we can just use unsafe_elements(), because the user cannot dereference the
+  // pointer anyway.
+  Element* ret = unsafe_elements() + current_size_;
+  current_size_ += n;
+  return ret;
+}
+
+template <typename Element>
+inline void RepeatedField<Element>::Resize(int new_size, const Element& value) {
+  GOOGLE_DCHECK_GE(new_size, 0);
+  if (new_size > current_size_) {
+    Reserve(new_size);
+    std::fill(&elements()[current_size_], &elements()[new_size], value);
+  }
+  current_size_ = new_size;
+}
+
+template <typename Element>
+inline const Element& RepeatedField<Element>::Get(int index) const {
+  GOOGLE_DCHECK_GE(index, 0);
+  GOOGLE_DCHECK_LT(index, current_size_);
+  return elements()[index];
+}
+
+template <typename Element>
+inline const Element& RepeatedField<Element>::at(int index) const {
+  GOOGLE_CHECK_GE(index, 0);
+  GOOGLE_CHECK_LT(index, current_size_);
+  return elements()[index];
+}
+
+template <typename Element>
+inline Element& RepeatedField<Element>::at(int index) {
+  GOOGLE_CHECK_GE(index, 0);
+  GOOGLE_CHECK_LT(index, current_size_);
+  return elements()[index];
+}
+
+template <typename Element>
+inline Element* RepeatedField<Element>::Mutable(int index) {
+  GOOGLE_DCHECK_GE(index, 0);
+  GOOGLE_DCHECK_LT(index, current_size_);
+  return &elements()[index];
+}
+
+template <typename Element>
+inline void RepeatedField<Element>::Set(int index, const Element& value) {
+  GOOGLE_DCHECK_GE(index, 0);
+  GOOGLE_DCHECK_LT(index, current_size_);
+  elements()[index] = value;
+}
+
+template <typename Element>
+inline void RepeatedField<Element>::Add(const Element& value) {
+  arc_ui32 size = current_size_;
+  if (static_cast<int>(size) == total_size_) {
+    // value could reference an element of the array. Reserving new space will
+    // invalidate the reference. So we must make a copy first.
+    auto tmp = value;
+    Reserve(total_size_ + 1);
+    elements()[size] = std::move(tmp);
+  } else {
+    elements()[size] = value;
+  }
+  current_size_ = size + 1;
+}
+
+template <typename Element>
+inline Element* RepeatedField<Element>::Add() {
+  arc_ui32 size = current_size_;
+  if (static_cast<int>(size) == total_size_) Reserve(total_size_ + 1);
+  auto ptr = &elements()[size];
+  current_size_ = size + 1;
+  return ptr;
+}
+
+template <typename Element>
+template <typename Iter>
+inline void RepeatedField<Element>::Add(Iter begin, Iter end) {
+  int reserve = internal::CalculateReserve(begin, end);
+  if (reserve != -1) {
+    if (reserve == 0) {
+      return;
+    }
+
+    Reserve(reserve + size());
+    // TODO(ckennelly):  The compiler loses track of the buffer freshly
+    // allocated by Reserve() by the time we call elements, so it cannot
+    // guarantee that elements does not alias [begin(), end()).
+    //
+    // If restrict is available, annotating the pointer obtained from elements()
+    // causes this to lower to memcpy instead of memmove.
+    std::copy(begin, end, elements() + size());
+    current_size_ = reserve + size();
+  } else {
+    FastAdder fast_adder(this);
+    for (; begin != end; ++begin) fast_adder.Add(*begin);
+  }
+}
+
+template <typename Element>
+inline void RepeatedField<Element>::RemoveLast() {
+  GOOGLE_DCHECK_GT(current_size_, 0);
+  current_size_--;
+}
+
+template <typename Element>
+void RepeatedField<Element>::ExtractSubrange(int start, int num,
+                                             Element* elements) {
+  GOOGLE_DCHECK_GE(start, 0);
+  GOOGLE_DCHECK_GE(num, 0);
+  GOOGLE_DCHECK_LE(start + num, this->current_size_);
+
+  // Save the values of the removed elements if requested.
+  if (elements != nullptr) {
+    for (int i = 0; i < num; ++i) elements[i] = this->Get(i + start);
+  }
+
+  // Slide remaining elements down to fill the gap.
+  if (num > 0) {
+    for (int i = start + num; i < this->current_size_; ++i)
+      this->Set(i - num, this->Get(i));
+    this->Truncate(this->current_size_ - num);
+  }
+}
+
+template <typename Element>
+inline void RepeatedField<Element>::Clear() {
+  current_size_ = 0;
+}
+
+template <typename Element>
+inline void RepeatedField<Element>::MergeFrom(const RepeatedField& other) {
+  GOOGLE_DCHECK_NE(&other, this);
+  if (other.current_size_ != 0) {
+    int existing_size = size();
+    Reserve(existing_size + other.size());
+    AddNAlreadyReserved(other.size());
+    CopyArray(Mutable(existing_size), &other.Get(0), other.size());
+  }
+}
+
+template <typename Element>
+inline void RepeatedField<Element>::CopyFrom(const RepeatedField& other) {
+  if (&other == this) return;
+  Clear();
+  MergeFrom(other);
+}
+
+template <typename Element>
+template <typename Iter>
+inline void RepeatedField<Element>::Assign(Iter begin, Iter end) {
+  Clear();
+  Add(begin, end);
+}
+
+template <typename Element>
+inline typename RepeatedField<Element>::iterator RepeatedField<Element>::erase(
+    const_iterator position) {
+  return erase(position, position + 1);
+}
+
+template <typename Element>
+inline typename RepeatedField<Element>::iterator RepeatedField<Element>::erase(
+    const_iterator first, const_iterator last) {
+  size_type first_offset = first - cbegin();
+  if (first != last) {
+    Truncate(std::copy(last, cend(), begin() + first_offset) - cbegin());
+  }
+  return begin() + first_offset;
+}
+
+template <typename Element>
+inline Element* RepeatedField<Element>::mutable_data() {
+  return unsafe_elements();
+}
+
+template <typename Element>
+inline const Element* RepeatedField<Element>::data() const {
+  return unsafe_elements();
+}
+
+template <typename Element>
+inline void RepeatedField<Element>::InternalSwap(RepeatedField* other) {
+  GOOGLE_DCHECK(this != other);
+
+  // Swap all fields at once.
+  static_assert(std::is_standard_layout<RepeatedField<Element>>::value,
+                "offsetof() requires standard layout before c++17");
+  internal::memswap<offsetof(RepeatedField, arena_or_elements_) +
+                    sizeof(this->arena_or_elements_) -
+                    offsetof(RepeatedField, current_size_)>(
+      reinterpret_cast<char*>(this) + offsetof(RepeatedField, current_size_),
+      reinterpret_cast<char*>(other) + offsetof(RepeatedField, current_size_));
+}
+
+template <typename Element>
+void RepeatedField<Element>::Swap(RepeatedField* other) {
+  if (this == other) return;
+#ifdef PROTOBUF_FORCE_COPY_IN_SWAP
+  if (GetArena() != nullptr && GetArena() == other->GetArena()) {
+#else   // PROTOBUF_FORCE_COPY_IN_SWAP
+  if (GetArena() == other->GetArena()) {
+#endif  // !PROTOBUF_FORCE_COPY_IN_SWAP
+    InternalSwap(other);
+  } else {
+    RepeatedField<Element> temp(other->GetArena());
+    temp.MergeFrom(*this);
+    CopyFrom(*other);
+    other->UnsafeArenaSwap(&temp);
+  }
+}
+
+template <typename Element>
+void RepeatedField<Element>::UnsafeArenaSwap(RepeatedField* other) {
+  if (this == other) return;
+  InternalSwap(other);
+}
+
+template <typename Element>
+void RepeatedField<Element>::SwapElements(int index1, int index2) {
+  using std::swap;  // enable ADL with fallback
+  swap(elements()[index1], elements()[index2]);
+}
+
+template <typename Element>
+inline typename RepeatedField<Element>::iterator
+RepeatedField<Element>::begin() {
+  return unsafe_elements();
+}
+template <typename Element>
+inline typename RepeatedField<Element>::const_iterator
+RepeatedField<Element>::begin() const {
+  return unsafe_elements();
+}
+template <typename Element>
+inline typename RepeatedField<Element>::const_iterator
+RepeatedField<Element>::cbegin() const {
+  return unsafe_elements();
+}
+template <typename Element>
+inline typename RepeatedField<Element>::iterator RepeatedField<Element>::end() {
+  return unsafe_elements() + current_size_;
+}
+template <typename Element>
+inline typename RepeatedField<Element>::const_iterator
+RepeatedField<Element>::end() const {
+  return unsafe_elements() + current_size_;
+}
+template <typename Element>
+inline typename RepeatedField<Element>::const_iterator
+RepeatedField<Element>::cend() const {
+  return unsafe_elements() + current_size_;
+}
+
+template <typename Element>
+inline size_t RepeatedField<Element>::SpaceUsedExcludingSelfLong() const {
+  return total_size_ > 0 ? (total_size_ * sizeof(Element) + kRepHeaderSize) : 0;
+}
+
+namespace internal {
+// Returns the new size for a reserved field based on its 'total_size' and the
+// requested 'new_size'. The result is clamped to the closed interval:
+//   [internal::kMinRepeatedFieldAllocationSize,
+//    std::numeric_limits<int>::max()]
+// Requires:
+//     new_size > total_size &&
+//     (total_size == 0 ||
+//      total_size >= kRepeatedFieldLowerClampLimit)
+inline int CalculateReserveSize(int total_size, int new_size) {
+  if (new_size < kRepeatedFieldLowerClampLimit) {
+    // Clamp to smallest allowed size.
+    return kRepeatedFieldLowerClampLimit;
+  }
+  if (total_size < kRepeatedFieldUpperClampLimit) {
+    return std::max(total_size * 2, new_size);
+  } else {
+    // Clamp to largest allowed size.
+    GOOGLE_DCHECK_GT(new_size, kRepeatedFieldUpperClampLimit);
+    return std::numeric_limits<int>::max();
+  }
+}
+}  // namespace internal
+
+// Avoid inlining of Reserve(): new, copy, and delete[] lead to a significant
+// amount of code bloat.
+template <typename Element>
+void RepeatedField<Element>::Reserve(int new_size) {
+  if (total_size_ >= new_size) return;
+  Rep* old_rep = total_size_ > 0 ? rep() : nullptr;
+  Rep* new_rep;
+  Arena* arena = GetArena();
+  new_size = internal::CalculateReserveSize(total_size_, new_size);
+  GOOGLE_DCHECK_LE(
+      static_cast<size_t>(new_size),
+      (std::numeric_limits<size_t>::max() - kRepHeaderSize) / sizeof(Element))
+      << "Requested size is too large to fit into size_t.";
+  size_t bytes =
+      kRepHeaderSize + sizeof(Element) * static_cast<size_t>(new_size);
+  if (arena == nullptr) {
+    new_rep = static_cast<Rep*>(::operator new(bytes));
+  } else {
+    new_rep = reinterpret_cast<Rep*>(Arena::CreateArray<char>(arena, bytes));
+  }
+  new_rep->arena = arena;
+  int old_total_size = total_size_;
+  // Already known: new_size >= internal::kMinRepeatedFieldAllocationSize
+  // Maintain invariant:
+  //     total_size_ == 0 ||
+  //     total_size_ >= internal::kMinRepeatedFieldAllocationSize
+  total_size_ = new_size;
+  arena_or_elements_ = new_rep->elements;
+  // Invoke placement-new on newly allocated elements. We shouldn't have to do
+  // this, since Element is supposed to be POD, but a previous version of this
+  // code allocated storage with "new Element[size]" and some code uses
+  // RepeatedField with non-POD types, relying on constructor invocation. If
+  // Element has a trivial constructor (e.g., arc_i32), gcc (tested with -O2)
+  // completely removes this loop because the loop body is empty, so this has no
+  // effect unless its side-effects are required for correctness.
+  // Note that we do this before MoveArray() below because Element's copy
+  // assignment implementation will want an initialized instance first.
+  Element* e = &elements()[0];
+  Element* limit = e + total_size_;
+  for (; e < limit; e++) {
+    new (e) Element;
+  }
+  if (current_size_ > 0) {
+    MoveArray(&elements()[0], old_rep->elements, current_size_);
+  }
+
+  // Likewise, we need to invoke destructors on the old array.
+  InternalDeallocate(old_rep, old_total_size);
+
+}
+
+template <typename Element>
+inline void RepeatedField<Element>::Truncate(int new_size) {
+  GOOGLE_DCHECK_LE(new_size, current_size_);
+  if (current_size_ > 0) {
+    current_size_ = new_size;
+  }
+}
+
+template <typename Element>
+inline void RepeatedField<Element>::MoveArray(Element* to, Element* from,
+                                              int array_size) {
+  CopyArray(to, from, array_size);
+}
+
+template <typename Element>
+inline void RepeatedField<Element>::CopyArray(Element* to, const Element* from,
+                                              int array_size) {
+  internal::ElementCopier<Element>()(to, from, array_size);
+}
+
+namespace internal {
+
+template <typename Element, bool HasTrivialCopy>
+void ElementCopier<Element, HasTrivialCopy>::operator()(Element* to,
+                                                        const Element* from,
+                                                        int array_size) {
+  std::copy(from, from + array_size, to);
+}
+
+template <typename Element>
+struct ElementCopier<Element, true> {
+  void operator()(Element* to, const Element* from, int array_size) {
+    memcpy(to, from, static_cast<size_t>(array_size) * sizeof(Element));
+  }
+};
+
+}  // namespace internal
+
+
+// -------------------------------------------------------------------
+
+// Iterators and helper functions that follow the spirit of the STL
+// std::back_insert_iterator and std::back_inserter but are tailor-made
+// for RepeatedField and RepeatedPtrField. Typical usage would be:
+//
+//   std::copy(some_sequence.begin(), some_sequence.end(),
+//             RepeatedFieldBackInserter(proto.mutable_sequence()));
+//
+// Ported by johannes from util/gtl/proto-array-iterators.h
+
+namespace internal {
+// A back inserter for RepeatedField objects.
+template <typename T>
+class RepeatedFieldBackInsertIterator {
+ public:
+  using iterator_category = std::output_iterator_tag;
+  using value_type = T;
+  using pointer = void;
+  using reference = void;
+  using difference_type = std::ptrdiff_t;
+
+  explicit RepeatedFieldBackInsertIterator(
+      RepeatedField<T>* const mutable_field)
+      : field_(mutable_field) {}
+  RepeatedFieldBackInsertIterator<T>& operator=(const T& value) {
+    field_->Add(value);
+    return *this;
+  }
+  RepeatedFieldBackInsertIterator<T>& operator*() { return *this; }
+  RepeatedFieldBackInsertIterator<T>& operator++() { return *this; }
+  RepeatedFieldBackInsertIterator<T>& operator++(int /* unused */) {
+    return *this;
+  }
+
+ private:
+  RepeatedField<T>* field_;
+};
+
+}  // namespace internal
+
+// Provides a back insert iterator for RepeatedField instances,
+// similar to std::back_inserter().
+template <typename T>
+internal::RepeatedFieldBackInsertIterator<T> RepeatedFieldBackInserter(
+    RepeatedField<T>* const mutable_field) {
+  return internal::RepeatedFieldBackInsertIterator<T>(mutable_field);
+}
+
+// Extern declarations of common instantiations to reduce library bloat.
+extern template class PROTOBUF_EXPORT_TEMPLATE_DECLARE RepeatedField<bool>;
+extern template class PROTOBUF_EXPORT_TEMPLATE_DECLARE RepeatedField<arc_i32>;
+extern template class PROTOBUF_EXPORT_TEMPLATE_DECLARE RepeatedField<arc_ui32>;
+extern template class PROTOBUF_EXPORT_TEMPLATE_DECLARE RepeatedField<arc_i64>;
+extern template class PROTOBUF_EXPORT_TEMPLATE_DECLARE RepeatedField<arc_ui64>;
+extern template class PROTOBUF_EXPORT_TEMPLATE_DECLARE RepeatedField<float>;
+extern template class PROTOBUF_EXPORT_TEMPLATE_DECLARE RepeatedField<double>;
+
+}  // namespace protobuf
+}  // namespace google
+
+#include <google/protobuf/port_undef.inc>
+
+#endif  // GOOGLE_PROTOBUF_REPEATED_FIELD_H__