Adding upstream version 124.0.1.upstream/124.0.1

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 1653 insertions, 0 deletions

diff --git a/mfbt/Vector.h b/mfbt/Vector.h
new file mode 100644
index 0000000000..380e272548
--- /dev/null
+++ b/mfbt/Vector.h
@@ -0,0 +1,1653 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+/* A type/length-parametrized vector class. */
+
+#ifndef mozilla_Vector_h
+#define mozilla_Vector_h
+
+#include <new>  // for placement new
+#include <type_traits>
+#include <utility>
+
+#include "mozilla/Alignment.h"
+#include "mozilla/AllocPolicy.h"
+#include "mozilla/ArrayUtils.h"  // for PointerRangeSize
+#include "mozilla/Assertions.h"
+#include "mozilla/Attributes.h"
+#include "mozilla/MathAlgorithms.h"
+#include "mozilla/MemoryReporting.h"
+#include "mozilla/OperatorNewExtensions.h"
+#include "mozilla/ReentrancyGuard.h"
+#include "mozilla/Span.h"
+#include "mozilla/TemplateLib.h"
+
+namespace mozilla {
+
+template <typename T, size_t N, class AllocPolicy>
+class Vector;
+
+namespace detail {
+
+/*
+ * Check that the given capacity wastes the minimal amount of space if
+ * allocated on the heap. This means that aCapacity*EltSize is as close to a
+ * power-of-two as possible. growStorageBy() is responsible for ensuring this.
+ */
+template <size_t EltSize>
+static bool CapacityHasExcessSpace(size_t aCapacity) {
+  size_t size = aCapacity * EltSize;
+  return RoundUpPow2(size) - size >= EltSize;
+}
+
+/*
+ * AllocPolicy can optionally provide a `computeGrowth<T>(size_t aOldElts,
+ * size_t aIncr)` method that returns the new number of elements to allocate
+ * when the current capacity is `aOldElts` and `aIncr` more are being
+ * requested. If the AllocPolicy does not have such a method, a fallback
+ * will be used that mostly will just round the new requested capacity up to
+ * the next power of two, which results in doubling capacity for the most part.
+ *
+ * If the new size would overflow some limit, `computeGrowth` returns 0.
+ *
+ * A simpler way would be to make computeGrowth() part of the API for all
+ * AllocPolicy classes, but this turns out to be rather complex because
+ * mozalloc.h defines a very widely-used InfallibleAllocPolicy, and yet it
+ * can only be compiled in limited contexts, eg within `extern "C"` and with
+ * -std=c++11 rather than a later version. That makes the headers that are
+ * necessary for the computation unavailable (eg mfbt/MathAlgorithms.h).
+ */
+
+// Fallback version.
+template <size_t EltSize>
+inline size_t GrowEltsByDoubling(size_t aOldElts, size_t aIncr) {
+  /*
+   * When choosing a new capacity, its size in bytes should is as close to 2**N
+   * bytes as possible.  2**N-sized requests are best because they are unlikely
+   * to be rounded up by the allocator.  Asking for a 2**N number of elements
+   * isn't as good, because if EltSize is not a power-of-two that would
+   * result in a non-2**N request size.
+   */
+
+  if (aIncr == 1) {
+    if (aOldElts == 0) {
+      return 1;
+    }
+
+    /* This case occurs in ~15--20% of the calls to Vector::growStorageBy. */
+
+    /*
+     * Will aOldSize * 4 * sizeof(T) overflow?  This condition limits a
+     * collection to 1GB of memory on a 32-bit system, which is a reasonable
+     * limit.  It also ensures that
+     *
+     *   static_cast<char*>(end()) - static_cast<char*>(begin())
+     *
+     * for a Vector doesn't overflow ptrdiff_t (see bug 510319).
+     */
+    if (MOZ_UNLIKELY(aOldElts &
+                     mozilla::tl::MulOverflowMask<4 * EltSize>::value)) {
+      return 0;
+    }
+
+    /*
+     * If we reach here, the existing capacity will have a size that is already
+     * as close to 2^N as sizeof(T) will allow.  Just double the capacity, and
+     * then there might be space for one more element.
+     */
+    size_t newElts = aOldElts * 2;
+    if (CapacityHasExcessSpace<EltSize>(newElts)) {
+      newElts += 1;
+    }
+    return newElts;
+  }
+
+  /* This case occurs in ~2% of the calls to Vector::growStorageBy. */
+  size_t newMinCap = aOldElts + aIncr;
+
+  /* Did aOldElts + aIncr overflow?  Will newMinCap * EltSize rounded up to the
+   * next power of two overflow PTRDIFF_MAX? */
+  if (MOZ_UNLIKELY(newMinCap < aOldElts ||
+                   newMinCap & tl::MulOverflowMask<4 * EltSize>::value)) {
+    return 0;
+  }
+
+  size_t newMinSize = newMinCap * EltSize;
+  size_t newSize = RoundUpPow2(newMinSize);
+  return newSize / EltSize;
+};
+
+// Fallback version.
+template <typename AP, size_t EltSize>
+static size_t ComputeGrowth(size_t aOldElts, size_t aIncr, int) {
+  return GrowEltsByDoubling<EltSize>(aOldElts, aIncr);
+}
+
+// If the AllocPolicy provides its own computeGrowth<EltSize> implementation,
+// use that.
+template <typename AP, size_t EltSize>
+static size_t ComputeGrowth(
+    size_t aOldElts, size_t aIncr,
+    decltype(std::declval<AP>().template computeGrowth<EltSize>(0, 0),
+             bool()) aOverloadSelector) {
+  size_t newElts = AP::template computeGrowth<EltSize>(aOldElts, aIncr);
+  MOZ_ASSERT(newElts <= PTRDIFF_MAX && newElts * EltSize <= PTRDIFF_MAX,
+             "invalid Vector size (see bug 510319)");
+  return newElts;
+}
+
+/*
+ * This template class provides a default implementation for vector operations
+ * when the element type is not known to be a POD, as judged by IsPod.
+ */
+template <typename T, size_t N, class AP, bool IsPod>
+struct VectorImpl {
+  /*
+   * Constructs an object in the uninitialized memory at *aDst with aArgs.
+   */
+  template <typename... Args>
+  MOZ_NONNULL(1)
+  static inline void new_(T* aDst, Args&&... aArgs) {
+    new (KnownNotNull, aDst) T(std::forward<Args>(aArgs)...);
+  }
+
+  /* Destroys constructed objects in the range [aBegin, aEnd). */
+  static inline void destroy(T* aBegin, T* aEnd) {
+    MOZ_ASSERT(aBegin <= aEnd);
+    for (T* p = aBegin; p < aEnd; ++p) {
+      p->~T();
+    }
+  }
+
+  /* Constructs objects in the uninitialized range [aBegin, aEnd). */
+  static inline void initialize(T* aBegin, T* aEnd) {
+    MOZ_ASSERT(aBegin <= aEnd);
+    for (T* p = aBegin; p < aEnd; ++p) {
+      new_(p);
+    }
+  }
+
+  /*
+   * Copy-constructs objects in the uninitialized range
+   * [aDst, aDst+(aSrcEnd-aSrcStart)) from the range [aSrcStart, aSrcEnd).
+   */
+  template <typename U>
+  static inline void copyConstruct(T* aDst, const U* aSrcStart,
+                                   const U* aSrcEnd) {
+    MOZ_ASSERT(aSrcStart <= aSrcEnd);
+    for (const U* p = aSrcStart; p < aSrcEnd; ++p, ++aDst) {
+      new_(aDst, *p);
+    }
+  }
+
+  /*
+   * Move-constructs objects in the uninitialized range
+   * [aDst, aDst+(aSrcEnd-aSrcStart)) from the range [aSrcStart, aSrcEnd).
+   */
+  template <typename U>
+  static inline void moveConstruct(T* aDst, U* aSrcStart, U* aSrcEnd) {
+    MOZ_ASSERT(aSrcStart <= aSrcEnd);
+    for (U* p = aSrcStart; p < aSrcEnd; ++p, ++aDst) {
+      new_(aDst, std::move(*p));
+    }
+  }
+
+  /*
+   * Copy-constructs objects in the uninitialized range [aDst, aDst+aN) from
+   * the same object aU.
+   */
+  template <typename U>
+  static inline void copyConstructN(T* aDst, size_t aN, const U& aU) {
+    for (T* end = aDst + aN; aDst < end; ++aDst) {
+      new_(aDst, aU);
+    }
+  }
+
+  /*
+   * Grows the given buffer to have capacity aNewCap, preserving the objects
+   * constructed in the range [begin, end) and updating aV. Assumes that (1)
+   * aNewCap has not overflowed, and (2) multiplying aNewCap by sizeof(T) will
+   * not overflow.
+   */
+  [[nodiscard]] static inline bool growTo(Vector<T, N, AP>& aV,
+                                          size_t aNewCap) {
+    MOZ_ASSERT(!aV.usingInlineStorage());
+    MOZ_ASSERT(!CapacityHasExcessSpace<sizeof(T)>(aNewCap));
+    T* newbuf = aV.template pod_malloc<T>(aNewCap);
+    if (MOZ_UNLIKELY(!newbuf)) {
+      return false;
+    }
+    T* dst = newbuf;
+    T* src = aV.beginNoCheck();
+    for (; src < aV.endNoCheck(); ++dst, ++src) {
+      new_(dst, std::move(*src));
+    }
+    VectorImpl::destroy(aV.beginNoCheck(), aV.endNoCheck());
+    aV.free_(aV.mBegin, aV.mTail.mCapacity);
+    aV.mBegin = newbuf;
+    /* aV.mLength is unchanged. */
+    aV.mTail.mCapacity = aNewCap;
+    return true;
+  }
+};
+
+/*
+ * This partial template specialization provides a default implementation for
+ * vector operations when the element type is known to be a POD, as judged by
+ * IsPod.
+ */
+template <typename T, size_t N, class AP>
+struct VectorImpl<T, N, AP, true> {
+  template <typename... Args>
+  MOZ_NONNULL(1)
+  static inline void new_(T* aDst, Args&&... aArgs) {
+    // Explicitly construct a local object instead of using a temporary since
+    // T(args...) will be treated like a C-style cast in the unary case and
+    // allow unsafe conversions. Both forms should be equivalent to an
+    // optimizing compiler.
+    T temp(std::forward<Args>(aArgs)...);
+    *aDst = temp;
+  }
+
+  static inline void destroy(T*, T*) {}
+
+  static inline void initialize(T* aBegin, T* aEnd) {
+    /*
+     * You would think that memset would be a big win (or even break even)
+     * when we know T is a POD. But currently it's not. This is probably
+     * because |append| tends to be given small ranges and memset requires
+     * a function call that doesn't get inlined.
+     *
+     * memset(aBegin, 0, sizeof(T) * (aEnd - aBegin));
+     */
+    MOZ_ASSERT(aBegin <= aEnd);
+    for (T* p = aBegin; p < aEnd; ++p) {
+      new_(p);
+    }
+  }
+
+  template <typename U>
+  static inline void copyConstruct(T* aDst, const U* aSrcStart,
+                                   const U* aSrcEnd) {
+    /*
+     * See above memset comment. Also, notice that copyConstruct is
+     * currently templated (T != U), so memcpy won't work without
+     * requiring T == U.
+     *
+     * memcpy(aDst, aSrcStart, sizeof(T) * (aSrcEnd - aSrcStart));
+     */
+    MOZ_ASSERT(aSrcStart <= aSrcEnd);
+    for (const U* p = aSrcStart; p < aSrcEnd; ++p, ++aDst) {
+      new_(aDst, *p);
+    }
+  }
+
+  template <typename U>
+  static inline void moveConstruct(T* aDst, const U* aSrcStart,
+                                   const U* aSrcEnd) {
+    copyConstruct(aDst, aSrcStart, aSrcEnd);
+  }
+
+  static inline void copyConstructN(T* aDst, size_t aN, const T& aT) {
+    for (T* end = aDst + aN; aDst < end; ++aDst) {
+      new_(aDst, aT);
+    }
+  }
+
+  [[nodiscard]] static inline bool growTo(Vector<T, N, AP>& aV,
+                                          size_t aNewCap) {
+    MOZ_ASSERT(!aV.usingInlineStorage());
+    MOZ_ASSERT(!CapacityHasExcessSpace<sizeof(T)>(aNewCap));
+    T* newbuf =
+        aV.template pod_realloc<T>(aV.mBegin, aV.mTail.mCapacity, aNewCap);
+    if (MOZ_UNLIKELY(!newbuf)) {
+      return false;
+    }
+    aV.mBegin = newbuf;
+    /* aV.mLength is unchanged. */
+    aV.mTail.mCapacity = aNewCap;
+    return true;
+  }
+};
+
+// A struct for TestVector.cpp to access private internal fields.
+// DO NOT DEFINE IN YOUR OWN CODE.
+struct VectorTesting;
+
+}  // namespace detail
+
+/*
+ * STL-like container providing a short-lived, dynamic buffer.  Vector calls the
+ * constructors/destructors of all elements stored in its internal buffer, so
+ * non-PODs may be safely used.  Additionally, Vector will store the first N
+ * elements in-place before resorting to dynamic allocation.
+ *
+ * T requirements:
+ *  - default and copy constructible, assignable, destructible
+ *  - operations do not throw
+ * MinInlineCapacity requirements:
+ *  - any value, however, MinInlineCapacity is clamped to min/max values
+ * AllocPolicy:
+ *  - see "Allocation policies" in AllocPolicy.h (defaults to
+ *    mozilla::MallocAllocPolicy)
+ *
+ * Vector is not reentrant: T member functions called during Vector member
+ * functions must not call back into the same object!
+ */
+template <typename T, size_t MinInlineCapacity = 0,
+          class AllocPolicy = MallocAllocPolicy>
+class MOZ_NON_PARAM Vector final : private AllocPolicy {
+  /* utilities */
+  static constexpr bool kElemIsPod =
+      std::is_trivial_v<T> && std::is_standard_layout_v<T>;
+  typedef detail::VectorImpl<T, MinInlineCapacity, AllocPolicy, kElemIsPod>
+      Impl;
+  friend struct detail::VectorImpl<T, MinInlineCapacity, AllocPolicy,
+                                   kElemIsPod>;
+
+  friend struct detail::VectorTesting;
+
+  [[nodiscard]] bool growStorageBy(size_t aIncr);
+  [[nodiscard]] bool convertToHeapStorage(size_t aNewCap);
+  [[nodiscard]] bool maybeCheckSimulatedOOM(size_t aRequestedSize);
+
+  /* magic constants */
+
+  /**
+   * The maximum space allocated for inline element storage.
+   *
+   * We reduce space by what the AllocPolicy base class and prior Vector member
+   * fields likely consume to attempt to play well with binary size classes.
+   */
+  static constexpr size_t kMaxInlineBytes =
+      1024 -
+      (sizeof(AllocPolicy) + sizeof(T*) + sizeof(size_t) + sizeof(size_t));
+
+  /**
+   * The number of T elements of inline capacity built into this Vector.  This
+   * is usually |MinInlineCapacity|, but it may be less (or zero!) for large T.
+   *
+   * We use a partially-specialized template (not explicit specialization, which
+   * is only allowed at namespace scope) to compute this value.  The benefit is
+   * that |sizeof(T)| need not be computed, and |T| doesn't have to be fully
+   * defined at the time |Vector<T>| appears, if no inline storage is requested.
+   */
+  template <size_t MinimumInlineCapacity, size_t Dummy>
+  struct ComputeCapacity {
+    static constexpr size_t value =
+        tl::Min<MinimumInlineCapacity, kMaxInlineBytes / sizeof(T)>::value;
+  };
+
+  template <size_t Dummy>
+  struct ComputeCapacity<0, Dummy> {
+    static constexpr size_t value = 0;
+  };
+
+  /** The actual inline capacity in number of elements T.  This may be zero! */
+  static constexpr size_t kInlineCapacity =
+      ComputeCapacity<MinInlineCapacity, 0>::value;
+
+  /* member data */
+
+  /*
+   * Pointer to the buffer, be it inline or heap-allocated. Only [mBegin,
+   * mBegin + mLength) hold valid constructed T objects. The range [mBegin +
+   * mLength, mBegin + mCapacity) holds uninitialized memory. The range
+   * [mBegin + mLength, mBegin + mReserved) also holds uninitialized memory
+   * previously allocated by a call to reserve().
+   */
+  T* mBegin;
+
+  /* Number of elements in the vector. */
+  size_t mLength;
+
+  /*
+   * Memory used to store capacity, reserved element count (debug builds only),
+   * and inline storage.  The simple "answer" is:
+   *
+   *   size_t mCapacity;
+   *   #ifdef DEBUG
+   *   size_t mReserved;
+   *   #endif
+   *   alignas(T) unsigned char mBytes[kInlineCapacity * sizeof(T)];
+   *
+   * but there are complications.  First, C++ forbids zero-sized arrays that
+   * might result.  Second, we don't want zero capacity to affect Vector's size
+   * (even empty classes take up a byte, unless they're base classes).
+   *
+   * Yet again, we eliminate the zero-sized array using partial specialization.
+   * And we eliminate potential size hit by putting capacity/reserved in one
+   * struct, then putting the array (if any) in a derived struct.  If no array
+   * is needed, the derived struct won't consume extra space.
+   */
+  struct CapacityAndReserved {
+    explicit CapacityAndReserved(size_t aCapacity, size_t aReserved)
+        : mCapacity(aCapacity)
+#ifdef DEBUG
+          ,
+          mReserved(aReserved)
+#endif
+    {
+    }
+    CapacityAndReserved() = default;
+
+    /* Max number of elements storable in the vector without resizing. */
+    size_t mCapacity;
+
+#ifdef DEBUG
+    /* Max elements of reserved or used space in this vector. */
+    size_t mReserved;
+#endif
+  };
+
+// Silence warnings about this struct possibly being padded dued to the
+// alignas() in it -- there's nothing we can do to avoid it.
+#ifdef _MSC_VER
+#  pragma warning(push)
+#  pragma warning(disable : 4324)
+#endif  // _MSC_VER
+
+  template <size_t Capacity, size_t Dummy>
+  struct CRAndStorage : CapacityAndReserved {
+    explicit CRAndStorage(size_t aCapacity, size_t aReserved)
+        : CapacityAndReserved(aCapacity, aReserved) {}
+    CRAndStorage() = default;
+
+    alignas(T) unsigned char mBytes[Capacity * sizeof(T)];
+
+    // GCC fails due to -Werror=strict-aliasing if |mBytes| is directly cast to
+    // T*.  Indirecting through this function addresses the problem.
+    void* data() { return mBytes; }
+
+    T* storage() { return static_cast<T*>(data()); }
+  };
+
+  template <size_t Dummy>
+  struct CRAndStorage<0, Dummy> : CapacityAndReserved {
+    explicit CRAndStorage(size_t aCapacity, size_t aReserved)
+        : CapacityAndReserved(aCapacity, aReserved) {}
+    CRAndStorage() = default;
+
+    T* storage() {
+      // If this returns |nullptr|, functions like |Vector::begin()| would too,
+      // breaking callers that pass a vector's elements as pointer/length to
+      // code that bounds its operation by length but (even just as a sanity
+      // check) always wants a non-null pointer.  Fake up an aligned, non-null
+      // pointer to support these callers.
+      return reinterpret_cast<T*>(sizeof(T));
+    }
+  };
+
+  CRAndStorage<kInlineCapacity, 0> mTail;
+
+#ifdef _MSC_VER
+#  pragma warning(pop)
+#endif  // _MSC_VER
+
+#ifdef DEBUG
+  friend class ReentrancyGuard;
+  bool mEntered;
+#endif
+
+  /* private accessors */
+
+  bool usingInlineStorage() const {
+    return mBegin == const_cast<Vector*>(this)->inlineStorage();
+  }
+
+  T* inlineStorage() { return mTail.storage(); }
+
+  T* beginNoCheck() const { return mBegin; }
+
+  T* endNoCheck() { return mBegin + mLength; }
+
+  const T* endNoCheck() const { return mBegin + mLength; }
+
+#ifdef DEBUG
+  /**
+   * The amount of explicitly allocated space in this vector that is immediately
+   * available to be filled by appending additional elements.  This value is
+   * always greater than or equal to |length()| -- the vector's actual elements
+   * are implicitly reserved.  This value is always less than or equal to
+   * |capacity()|.  It may be explicitly increased using the |reserve()| method.
+   */
+  size_t reserved() const {
+    MOZ_ASSERT(mLength <= mTail.mReserved);
+    MOZ_ASSERT(mTail.mReserved <= mTail.mCapacity);
+    return mTail.mReserved;
+  }
+#endif
+
+  bool internalEnsureCapacity(size_t aNeeded);
+
+  /* Append operations guaranteed to succeed due to pre-reserved space. */
+  template <typename U>
+  void internalAppend(U&& aU);
+  template <typename U, size_t O, class BP>
+  void internalAppendAll(const Vector<U, O, BP>& aU);
+  void internalAppendN(const T& aT, size_t aN);
+  template <typename U>
+  void internalAppend(const U* aBegin, size_t aLength);
+  template <typename U>
+  void internalMoveAppend(U* aBegin, size_t aLength);
+
+ public:
+  static const size_t sMaxInlineStorage = MinInlineCapacity;
+
+  typedef T ElementType;
+
+  explicit Vector(AllocPolicy);
+  Vector() : Vector(AllocPolicy()) {}
+
+  Vector(Vector&&);            /* Move constructor. */
+  Vector& operator=(Vector&&); /* Move assignment. */
+  ~Vector();
+
+  /* accessors */
+
+  const AllocPolicy& allocPolicy() const { return *this; }
+
+  AllocPolicy& allocPolicy() { return *this; }
+
+  enum { InlineLength = MinInlineCapacity };
+
+  size_t length() const { return mLength; }
+
+  bool empty() const { return mLength == 0; }
+
+  size_t capacity() const { return mTail.mCapacity; }
+
+  T* begin() {
+    MOZ_ASSERT(!mEntered);
+    return mBegin;
+  }
+
+  const T* begin() const {
+    MOZ_ASSERT(!mEntered);
+    return mBegin;
+  }
+
+  T* end() {
+    MOZ_ASSERT(!mEntered);
+    return mBegin + mLength;
+  }
+
+  const T* end() const {
+    MOZ_ASSERT(!mEntered);
+    return mBegin + mLength;
+  }
+
+  T& operator[](size_t aIndex) {
+    MOZ_ASSERT(!mEntered);
+    MOZ_ASSERT(aIndex < mLength);
+    return begin()[aIndex];
+  }
+
+  const T& operator[](size_t aIndex) const {
+    MOZ_ASSERT(!mEntered);
+    MOZ_ASSERT(aIndex < mLength);
+    return begin()[aIndex];
+  }
+
+  T& back() {
+    MOZ_ASSERT(!mEntered);
+    MOZ_ASSERT(!empty());
+    return *(end() - 1);
+  }
+
+  const T& back() const {
+    MOZ_ASSERT(!mEntered);
+    MOZ_ASSERT(!empty());
+    return *(end() - 1);
+  }
+
+  operator mozilla::Span<const T>() const {
+    // Explicitly specify template argument here to avoid instantiating Span<T>
+    // first and then implicitly converting to Span<const T>
+    return mozilla::Span<const T>{mBegin, mLength};
+  }
+
+  operator mozilla::Span<T>() { return mozilla::Span{mBegin, mLength}; }
+
+  class Range {
+    friend class Vector;
+    T* mCur;
+    T* mEnd;
+    Range(T* aCur, T* aEnd) : mCur(aCur), mEnd(aEnd) {
+      MOZ_ASSERT(aCur <= aEnd);
+    }
+
+   public:
+    bool empty() const { return mCur == mEnd; }
+    size_t remain() const { return PointerRangeSize(mCur, mEnd); }
+    T& front() const {
+      MOZ_ASSERT(!empty());
+      return *mCur;
+    }
+    void popFront() {
+      MOZ_ASSERT(!empty());
+      ++mCur;
+    }
+    T popCopyFront() {
+      MOZ_ASSERT(!empty());
+      return *mCur++;
+    }
+  };
+
+  class ConstRange {
+    friend class Vector;
+    const T* mCur;
+    const T* mEnd;
+    ConstRange(const T* aCur, const T* aEnd) : mCur(aCur), mEnd(aEnd) {
+      MOZ_ASSERT(aCur <= aEnd);
+    }
+
+   public:
+    bool empty() const { return mCur == mEnd; }
+    size_t remain() const { return PointerRangeSize(mCur, mEnd); }
+    const T& front() const {
+      MOZ_ASSERT(!empty());
+      return *mCur;
+    }
+    void popFront() {
+      MOZ_ASSERT(!empty());
+      ++mCur;
+    }
+    T popCopyFront() {
+      MOZ_ASSERT(!empty());
+      return *mCur++;
+    }
+  };
+
+  Range all() { return Range(begin(), end()); }
+  ConstRange all() const { return ConstRange(begin(), end()); }
+
+  /* mutators */
+
+  /**
+   * Reverse the order of the elements in the vector in place.
+   */
+  void reverse();
+
+  /**
+   * Given that the vector is empty, grow the internal capacity to |aRequest|,
+   * keeping the length 0.
+   */
+  [[nodiscard]] bool initCapacity(size_t aRequest);
+
+  /**
+   * Given that the vector is empty, grow the internal capacity and length to
+   * |aRequest| leaving the elements' memory completely uninitialized (with all
+   * the associated hazards and caveats). This avoids the usual allocation-size
+   * rounding that happens in resize and overhead of initialization for elements
+   * that are about to be overwritten.
+   */
+  [[nodiscard]] bool initLengthUninitialized(size_t aRequest);
+
+  /**
+   * If reserve(aRequest) succeeds and |aRequest >= length()|, then appending
+   * |aRequest - length()| elements, in any sequence of append/appendAll calls,
+   * is guaranteed to succeed.
+   *
+   * A request to reserve an amount less than the current length does not affect
+   * reserved space.
+   */
+  [[nodiscard]] bool reserve(size_t aRequest);
+
+  /**
+   * Destroy elements in the range [end() - aIncr, end()). Does not deallocate
+   * or unreserve storage for those elements.
+   */
+  void shrinkBy(size_t aIncr);
+
+  /**
+   * Destroy elements in the range [aNewLength, end()). Does not deallocate
+   * or unreserve storage for those elements.
+   */
+  void shrinkTo(size_t aNewLength);
+
+  /** Grow the vector by aIncr elements. */
+  [[nodiscard]] bool growBy(size_t aIncr);
+
+  /** Call shrinkBy or growBy based on whether newSize > length(). */
+  [[nodiscard]] bool resize(size_t aNewLength);
+
+  /**
+   * Increase the length of the vector, but don't initialize the new elements
+   * -- leave them as uninitialized memory.
+   */
+  [[nodiscard]] bool growByUninitialized(size_t aIncr);
+  void infallibleGrowByUninitialized(size_t aIncr);
+  [[nodiscard]] bool resizeUninitialized(size_t aNewLength);
+
+  /** Shorthand for shrinkBy(length()). */
+  void clear();
+
+  /** Clears and releases any heap-allocated storage. */
+  void clearAndFree();
+
+  /**
+   * Shrinks the storage to drop excess capacity if possible.
+   *
+   * The return value indicates whether the operation succeeded, otherwise, it
+   * represents an OOM. The bool can be safely ignored unless you want to
+   * provide the guarantee that `length() == capacity()`.
+   *
+   * For PODs, it calls the AllocPolicy's pod_realloc. For non-PODs, it moves
+   * the elements into the new storage.
+   */
+  bool shrinkStorageToFit();
+
+  /**
+   * If true, appending |aNeeded| elements won't reallocate elements storage.
+   * This *doesn't* mean that infallibleAppend may be used!  You still must
+   * reserve the extra space, even if this method indicates that appends won't
+   * need to reallocate elements storage.
+   */
+  bool canAppendWithoutRealloc(size_t aNeeded) const;
+
+  /** Potentially fallible append operations. */
+
+  /**
+   * This can take either a T& or a T&&. Given a T&&, it moves |aU| into the
+   * vector, instead of copying it. If it fails, |aU| is left unmoved. ("We are
+   * not amused.")
+   */
+  template <typename U>
+  [[nodiscard]] bool append(U&& aU);
+
+  /**
+   * Construct a T in-place as a new entry at the end of this vector.
+   */
+  template <typename... Args>
+  [[nodiscard]] bool emplaceBack(Args&&... aArgs) {
+    if (!growByUninitialized(1)) return false;
+    Impl::new_(&back(), std::forward<Args>(aArgs)...);
+    return true;
+  }
+
+  template <typename U, size_t O, class BP>
+  [[nodiscard]] bool appendAll(const Vector<U, O, BP>& aU);
+  template <typename U, size_t O, class BP>
+  [[nodiscard]] bool appendAll(Vector<U, O, BP>&& aU);
+  [[nodiscard]] bool appendN(const T& aT, size_t aN);
+  template <typename U>
+  [[nodiscard]] bool append(const U* aBegin, const U* aEnd);
+  template <typename U>
+  [[nodiscard]] bool append(const U* aBegin, size_t aLength);
+  template <typename U>
+  [[nodiscard]] bool moveAppend(U* aBegin, U* aEnd);
+
+  /*
+   * Guaranteed-infallible append operations for use upon vectors whose
+   * memory has been pre-reserved.  Don't use this if you haven't reserved the
+   * memory!
+   */
+  template <typename U>
+  void infallibleAppend(U&& aU) {
+    internalAppend(std::forward<U>(aU));
+  }
+  void infallibleAppendN(const T& aT, size_t aN) { internalAppendN(aT, aN); }
+  template <typename U>
+  void infallibleAppend(const U* aBegin, const U* aEnd) {
+    internalAppend(aBegin, PointerRangeSize(aBegin, aEnd));
+  }
+  template <typename U>
+  void infallibleAppend(const U* aBegin, size_t aLength) {
+    internalAppend(aBegin, aLength);
+  }
+  template <typename... Args>
+  void infallibleEmplaceBack(Args&&... aArgs) {
+    infallibleGrowByUninitialized(1);
+    Impl::new_(&back(), std::forward<Args>(aArgs)...);
+  }
+
+  void popBack();
+
+  T popCopy();
+
+  /**
+   * If elements are stored in-place, return nullptr and leave this vector
+   * unmodified.
+   *
+   * Otherwise return this vector's elements buffer, and clear this vector as if
+   * by clearAndFree(). The caller now owns the buffer and is responsible for
+   * deallocating it consistent with this vector's AllocPolicy.
+   *
+   * N.B. Although a T*, only the range [0, length()) is constructed.
+   */
+  [[nodiscard]] T* extractRawBuffer();
+
+  /**
+   * If elements are stored in-place, allocate a new buffer, move this vector's
+   * elements into it, and return that buffer.
+   *
+   * Otherwise return this vector's elements buffer. The caller now owns the
+   * buffer and is responsible for deallocating it consistent with this vector's
+   * AllocPolicy.
+   *
+   * This vector is cleared, as if by clearAndFree(), when this method
+   * succeeds. This method fails and returns nullptr only if new elements buffer
+   * allocation fails.
+   *
+   * N.B. Only the range [0, length()) of the returned buffer is constructed.
+   * If any of these elements are uninitialized (as growByUninitialized
+   * enables), behavior is undefined.
+   */
+  [[nodiscard]] T* extractOrCopyRawBuffer();
+
+  /**
+   * Transfer ownership of an array of objects into the vector.  The caller
+   * must have allocated the array in accordance with this vector's
+   * AllocPolicy.
+   *
+   * N.B. This call assumes that there are no uninitialized elements in the
+   *      passed range [aP, aP + aLength). The range [aP + aLength, aP +
+   *      aCapacity) must be allocated uninitialized memory.
+   */
+  void replaceRawBuffer(T* aP, size_t aLength, size_t aCapacity);
+
+  /**
+   * Transfer ownership of an array of objects into the vector.  The caller
+   * must have allocated the array in accordance with this vector's
+   * AllocPolicy.
+   *
+   * N.B. This call assumes that there are no uninitialized elements in the
+   *      passed array.
+   */
+  void replaceRawBuffer(T* aP, size_t aLength);
+
+  /**
+   * Places |aVal| at position |aP|, shifting existing elements from |aP| onward
+   * one position higher.  On success, |aP| should not be reused because it'll
+   * be a dangling pointer if reallocation of the vector storage occurred; the
+   * return value should be used instead.  On failure, nullptr is returned.
+   *
+   * Example usage:
+   *
+   *   if (!(p = vec.insert(p, val))) {
+   *     <handle failure>
+   *   }
+   *   <keep working with p>
+   *
+   * This is inherently a linear-time operation.  Be careful!
+   */
+  template <typename U>
+  [[nodiscard]] T* insert(T* aP, U&& aVal);
+
+  /**
+   * Removes the element |aT|, which must fall in the bounds [begin, end),
+   * shifting existing elements from |aT + 1| onward one position lower.
+   */
+  void erase(T* aT);
+
+  /**
+   * Removes the elements [|aBegin|, |aEnd|), which must fall in the bounds
+   * [begin, end), shifting existing elements from |aEnd| onward to aBegin's old
+   * position.
+   */
+  void erase(T* aBegin, T* aEnd);
+
+  /**
+   * Removes all elements that satisfy the predicate, shifting existing elements
+   * lower to fill erased gaps.
+   */
+  template <typename Pred>
+  void eraseIf(Pred aPred);
+
+  /**
+   * Removes all elements that compare equal to |aU|, shifting existing elements
+   * lower to fill erased gaps.
+   */
+  template <typename U>
+  void eraseIfEqual(const U& aU);
+
+  /**
+   * Measure the size of the vector's heap-allocated storage.
+   */
+  size_t sizeOfExcludingThis(MallocSizeOf aMallocSizeOf) const;
+
+  /**
+   * Like sizeOfExcludingThis, but also measures the size of the vector
+   * object (which must be heap-allocated) itself.
+   */
+  size_t sizeOfIncludingThis(MallocSizeOf aMallocSizeOf) const;
+
+  void swap(Vector& aOther);
+
+ private:
+  Vector(const Vector&) = delete;
+  void operator=(const Vector&) = delete;
+};
+
+/* This does the re-entrancy check plus several other sanity checks. */
+#define MOZ_REENTRANCY_GUARD_ET_AL                                         \
+  ReentrancyGuard g(*this);                                                \
+  MOZ_ASSERT_IF(usingInlineStorage(), mTail.mCapacity == kInlineCapacity); \
+  MOZ_ASSERT(reserved() <= mTail.mCapacity);                               \
+  MOZ_ASSERT(mLength <= reserved());                                       \
+  MOZ_ASSERT(mLength <= mTail.mCapacity)
+
+/* Vector Implementation */
+
+template <typename T, size_t N, class AP>
+MOZ_ALWAYS_INLINE Vector<T, N, AP>::Vector(AP aAP)
+    : AP(std::move(aAP)),
+      mLength(0),
+      mTail(kInlineCapacity, 0)
+#ifdef DEBUG
+      ,
+      mEntered(false)
+#endif
+{
+  mBegin = inlineStorage();
+}
+
+/* Move constructor. */
+template <typename T, size_t N, class AllocPolicy>
+MOZ_ALWAYS_INLINE Vector<T, N, AllocPolicy>::Vector(Vector&& aRhs)
+    : AllocPolicy(std::move(aRhs))
+#ifdef DEBUG
+      ,
+      mEntered(false)
+#endif
+{
+  mLength = aRhs.mLength;
+  mTail.mCapacity = aRhs.mTail.mCapacity;
+#ifdef DEBUG
+  mTail.mReserved = aRhs.mTail.mReserved;
+#endif
+
+  if (aRhs.usingInlineStorage()) {
+    /* We can't move the buffer over in this case, so copy elements. */
+    mBegin = inlineStorage();
+    Impl::moveConstruct(mBegin, aRhs.beginNoCheck(), aRhs.endNoCheck());
+    /*
+     * Leave aRhs's mLength, mBegin, mCapacity, and mReserved as they are.
+     * The elements in its in-line storage still need to be destroyed.
+     */
+  } else {
+    /*
+     * Take src's buffer, and turn src into an empty vector using
+     * in-line storage.
+     */
+    mBegin = aRhs.mBegin;
+    aRhs.mBegin = aRhs.inlineStorage();
+    aRhs.mTail.mCapacity = kInlineCapacity;
+    aRhs.mLength = 0;
+#ifdef DEBUG
+    aRhs.mTail.mReserved = 0;
+#endif
+  }
+}
+
+/* Move assignment. */
+template <typename T, size_t N, class AP>
+MOZ_ALWAYS_INLINE Vector<T, N, AP>& Vector<T, N, AP>::operator=(Vector&& aRhs) {
+  MOZ_ASSERT(this != &aRhs, "self-move assignment is prohibited");
+  this->~Vector();
+  new (KnownNotNull, this) Vector(std::move(aRhs));
+  return *this;
+}
+
+template <typename T, size_t N, class AP>
+MOZ_ALWAYS_INLINE Vector<T, N, AP>::~Vector() {
+  MOZ_REENTRANCY_GUARD_ET_AL;
+  Impl::destroy(beginNoCheck(), endNoCheck());
+  if (!usingInlineStorage()) {
+    this->free_(beginNoCheck(), mTail.mCapacity);
+  }
+}
+
+template <typename T, size_t N, class AP>
+MOZ_ALWAYS_INLINE void Vector<T, N, AP>::reverse() {
+  MOZ_REENTRANCY_GUARD_ET_AL;
+  T* elems = mBegin;
+  size_t len = mLength;
+  size_t mid = len / 2;
+  for (size_t i = 0; i < mid; i++) {
+    std::swap(elems[i], elems[len - i - 1]);
+  }
+}
+
+/*
+ * This function will create a new heap buffer with capacity aNewCap,
+ * move all elements in the inline buffer to this new buffer,
+ * and fail on OOM.
+ */
+template <typename T, size_t N, class AP>
+inline bool Vector<T, N, AP>::convertToHeapStorage(size_t aNewCap) {
+  MOZ_ASSERT(usingInlineStorage());
+
+  /* Allocate buffer. */
+  MOZ_ASSERT(!detail::CapacityHasExcessSpace<sizeof(T)>(aNewCap));
+  T* newBuf = this->template pod_malloc<T>(aNewCap);
+  if (MOZ_UNLIKELY(!newBuf)) {
+    return false;
+  }
+
+  /* Copy inline elements into heap buffer. */
+  Impl::moveConstruct(newBuf, beginNoCheck(), endNoCheck());
+  Impl::destroy(beginNoCheck(), endNoCheck());
+
+  /* Switch in heap buffer. */
+  mBegin = newBuf;
+  /* mLength is unchanged. */
+  mTail.mCapacity = aNewCap;
+  return true;
+}
+
+template <typename T, size_t N, class AP>
+MOZ_NEVER_INLINE bool Vector<T, N, AP>::growStorageBy(size_t aIncr) {
+  MOZ_ASSERT(mLength + aIncr > mTail.mCapacity);
+
+  size_t newCap;
+
+  if (aIncr == 1 && usingInlineStorage()) {
+    /* This case occurs in ~70--80% of the calls to this function. */
+    constexpr size_t newSize =
+        tl::RoundUpPow2<(kInlineCapacity + 1) * sizeof(T)>::value;
+    static_assert(newSize / sizeof(T) > 0,
+                  "overflow when exceeding inline Vector storage");
+    newCap = newSize / sizeof(T);
+  } else {
+    newCap = detail::ComputeGrowth<AP, sizeof(T)>(mLength, aIncr, true);
+    if (MOZ_UNLIKELY(newCap == 0)) {
+      this->reportAllocOverflow();
+      return false;
+    }
+  }
+
+  if (usingInlineStorage()) {
+    return convertToHeapStorage(newCap);
+  }
+
+  return Impl::growTo(*this, newCap);
+}
+
+template <typename T, size_t N, class AP>
+inline bool Vector<T, N, AP>::initCapacity(size_t aRequest) {
+  MOZ_ASSERT(empty());
+  MOZ_ASSERT(usingInlineStorage());
+  if (aRequest == 0) {
+    return true;
+  }
+  T* newbuf = this->template pod_malloc<T>(aRequest);
+  if (MOZ_UNLIKELY(!newbuf)) {
+    return false;
+  }
+  mBegin = newbuf;
+  mTail.mCapacity = aRequest;
+#ifdef DEBUG
+  mTail.mReserved = aRequest;
+#endif
+  return true;
+}
+
+template <typename T, size_t N, class AP>
+inline bool Vector<T, N, AP>::initLengthUninitialized(size_t aRequest) {
+  if (!initCapacity(aRequest)) {
+    return false;
+  }
+  infallibleGrowByUninitialized(aRequest);
+  return true;
+}
+
+template <typename T, size_t N, class AP>
+inline bool Vector<T, N, AP>::maybeCheckSimulatedOOM(size_t aRequestedSize) {
+  if (aRequestedSize <= N) {
+    return true;
+  }
+
+#ifdef DEBUG
+  if (aRequestedSize <= mTail.mReserved) {
+    return true;
+  }
+#endif
+
+  return allocPolicy().checkSimulatedOOM();
+}
+
+template <typename T, size_t N, class AP>
+inline bool Vector<T, N, AP>::reserve(size_t aRequest) {
+  MOZ_REENTRANCY_GUARD_ET_AL;
+  if (aRequest > mTail.mCapacity) {
+    if (MOZ_UNLIKELY(!growStorageBy(aRequest - mLength))) {
+      return false;
+    }
+  } else if (!maybeCheckSimulatedOOM(aRequest)) {
+    return false;
+  }
+#ifdef DEBUG
+  if (aRequest > mTail.mReserved) {
+    mTail.mReserved = aRequest;
+  }
+  MOZ_ASSERT(mLength <= mTail.mReserved);
+  MOZ_ASSERT(mTail.mReserved <= mTail.mCapacity);
+#endif
+  return true;
+}
+
+template <typename T, size_t N, class AP>
+inline void Vector<T, N, AP>::shrinkBy(size_t aIncr) {
+  MOZ_REENTRANCY_GUARD_ET_AL;
+  MOZ_ASSERT(aIncr <= mLength);
+  Impl::destroy(endNoCheck() - aIncr, endNoCheck());
+  mLength -= aIncr;
+}
+
+template <typename T, size_t N, class AP>
+MOZ_ALWAYS_INLINE void Vector<T, N, AP>::shrinkTo(size_t aNewLength) {
+  MOZ_ASSERT(aNewLength <= mLength);
+  shrinkBy(mLength - aNewLength);
+}
+
+template <typename T, size_t N, class AP>
+MOZ_ALWAYS_INLINE bool Vector<T, N, AP>::growBy(size_t aIncr) {
+  MOZ_REENTRANCY_GUARD_ET_AL;
+  if (aIncr > mTail.mCapacity - mLength) {
+    if (MOZ_UNLIKELY(!growStorageBy(aIncr))) {
+      return false;
+    }
+  } else if (!maybeCheckSimulatedOOM(mLength + aIncr)) {
+    return false;
+  }
+  MOZ_ASSERT(mLength + aIncr <= mTail.mCapacity);
+  T* newend = endNoCheck() + aIncr;
+  Impl::initialize(endNoCheck(), newend);
+  mLength += aIncr;
+#ifdef DEBUG
+  if (mLength > mTail.mReserved) {
+    mTail.mReserved = mLength;
+  }
+#endif
+  return true;
+}
+
+template <typename T, size_t N, class AP>
+MOZ_ALWAYS_INLINE bool Vector<T, N, AP>::growByUninitialized(size_t aIncr) {
+  MOZ_REENTRANCY_GUARD_ET_AL;
+  if (aIncr > mTail.mCapacity - mLength) {
+    if (MOZ_UNLIKELY(!growStorageBy(aIncr))) {
+      return false;
+    }
+  } else if (!maybeCheckSimulatedOOM(mLength + aIncr)) {
+    return false;
+  }
+#ifdef DEBUG
+  if (mLength + aIncr > mTail.mReserved) {
+    mTail.mReserved = mLength + aIncr;
+  }
+#endif
+  infallibleGrowByUninitialized(aIncr);
+  return true;
+}
+
+template <typename T, size_t N, class AP>
+MOZ_ALWAYS_INLINE void Vector<T, N, AP>::infallibleGrowByUninitialized(
+    size_t aIncr) {
+  MOZ_ASSERT(mLength + aIncr <= reserved());
+  mLength += aIncr;
+}
+
+template <typename T, size_t N, class AP>
+inline bool Vector<T, N, AP>::resize(size_t aNewLength) {
+  size_t curLength = mLength;
+  if (aNewLength > curLength) {
+    return growBy(aNewLength - curLength);
+  }
+  shrinkBy(curLength - aNewLength);
+  return true;
+}
+
+template <typename T, size_t N, class AP>
+MOZ_ALWAYS_INLINE bool Vector<T, N, AP>::resizeUninitialized(
+    size_t aNewLength) {
+  size_t curLength = mLength;
+  if (aNewLength > curLength) {
+    return growByUninitialized(aNewLength - curLength);
+  }
+  shrinkBy(curLength - aNewLength);
+  return true;
+}
+
+template <typename T, size_t N, class AP>
+inline void Vector<T, N, AP>::clear() {
+  MOZ_REENTRANCY_GUARD_ET_AL;
+  Impl::destroy(beginNoCheck(), endNoCheck());
+  mLength = 0;
+}
+
+template <typename T, size_t N, class AP>
+inline void Vector<T, N, AP>::clearAndFree() {
+  clear();
+
+  if (usingInlineStorage()) {
+    return;
+  }
+  this->free_(beginNoCheck(), mTail.mCapacity);
+  mBegin = inlineStorage();
+  mTail.mCapacity = kInlineCapacity;
+#ifdef DEBUG
+  mTail.mReserved = 0;
+#endif
+}
+
+template <typename T, size_t N, class AP>
+inline bool Vector<T, N, AP>::shrinkStorageToFit() {
+  MOZ_REENTRANCY_GUARD_ET_AL;
+
+  const auto length = this->length();
+  if (usingInlineStorage() || length == capacity()) {
+    return true;
+  }
+
+  if (!length) {
+    this->free_(beginNoCheck(), mTail.mCapacity);
+    mBegin = inlineStorage();
+    mTail.mCapacity = kInlineCapacity;
+#ifdef DEBUG
+    mTail.mReserved = 0;
+#endif
+    return true;
+  }
+
+  T* newBuf;
+  size_t newCap;
+  if (length <= kInlineCapacity) {
+    newBuf = inlineStorage();
+    newCap = kInlineCapacity;
+  } else {
+    if (kElemIsPod) {
+      newBuf = this->template pod_realloc<T>(beginNoCheck(), mTail.mCapacity,
+                                             length);
+    } else {
+      newBuf = this->template pod_malloc<T>(length);
+    }
+    if (MOZ_UNLIKELY(!newBuf)) {
+      return false;
+    }
+    newCap = length;
+  }
+  if (!kElemIsPod || newBuf == inlineStorage()) {
+    Impl::moveConstruct(newBuf, beginNoCheck(), endNoCheck());
+    Impl::destroy(beginNoCheck(), endNoCheck());
+  }
+  if (!kElemIsPod) {
+    this->free_(beginNoCheck(), mTail.mCapacity);
+  }
+  mBegin = newBuf;
+  mTail.mCapacity = newCap;
+#ifdef DEBUG
+  mTail.mReserved = length;
+#endif
+  return true;
+}
+
+template <typename T, size_t N, class AP>
+inline bool Vector<T, N, AP>::canAppendWithoutRealloc(size_t aNeeded) const {
+  return mLength + aNeeded <= mTail.mCapacity;
+}
+
+template <typename T, size_t N, class AP>
+template <typename U, size_t O, class BP>
+MOZ_ALWAYS_INLINE void Vector<T, N, AP>::internalAppendAll(
+    const Vector<U, O, BP>& aOther) {
+  internalAppend(aOther.begin(), aOther.length());
+}
+
+template <typename T, size_t N, class AP>
+template <typename U>
+MOZ_ALWAYS_INLINE void Vector<T, N, AP>::internalAppend(U&& aU) {
+  MOZ_ASSERT(mLength + 1 <= mTail.mReserved);
+  MOZ_ASSERT(mTail.mReserved <= mTail.mCapacity);
+  Impl::new_(endNoCheck(), std::forward<U>(aU));
+  ++mLength;
+}
+
+template <typename T, size_t N, class AP>
+MOZ_ALWAYS_INLINE bool Vector<T, N, AP>::appendN(const T& aT, size_t aNeeded) {
+  MOZ_REENTRANCY_GUARD_ET_AL;
+  if (mLength + aNeeded > mTail.mCapacity) {
+    if (MOZ_UNLIKELY(!growStorageBy(aNeeded))) {
+      return false;
+    }
+  } else if (!maybeCheckSimulatedOOM(mLength + aNeeded)) {
+    return false;
+  }
+#ifdef DEBUG
+  if (mLength + aNeeded > mTail.mReserved) {
+    mTail.mReserved = mLength + aNeeded;
+  }
+#endif
+  internalAppendN(aT, aNeeded);
+  return true;
+}
+
+template <typename T, size_t N, class AP>
+MOZ_ALWAYS_INLINE void Vector<T, N, AP>::internalAppendN(const T& aT,
+                                                         size_t aNeeded) {
+  MOZ_ASSERT(mLength + aNeeded <= mTail.mReserved);
+  MOZ_ASSERT(mTail.mReserved <= mTail.mCapacity);
+  Impl::copyConstructN(endNoCheck(), aNeeded, aT);
+  mLength += aNeeded;
+}
+
+template <typename T, size_t N, class AP>
+template <typename U>
+inline T* Vector<T, N, AP>::insert(T* aP, U&& aVal) {
+  MOZ_ASSERT(begin() <= aP);
+  MOZ_ASSERT(aP <= end());
+  size_t pos = aP - begin();
+  MOZ_ASSERT(pos <= mLength);
+  size_t oldLength = mLength;
+  if (pos == oldLength) {
+    if (!append(std::forward<U>(aVal))) {
+      return nullptr;
+    }
+  } else {
+    T oldBack = std::move(back());
+    if (!append(std::move(oldBack))) {
+      return nullptr;
+    }
+    for (size_t i = oldLength - 1; i > pos; --i) {
+      (*this)[i] = std::move((*this)[i - 1]);
+    }
+    (*this)[pos] = std::forward<U>(aVal);
+  }
+  return begin() + pos;
+}
+
+template <typename T, size_t N, class AP>
+inline void Vector<T, N, AP>::erase(T* aIt) {
+  MOZ_ASSERT(begin() <= aIt);
+  MOZ_ASSERT(aIt < end());
+  while (aIt + 1 < end()) {
+    *aIt = std::move(*(aIt + 1));
+    ++aIt;
+  }
+  popBack();
+}
+
+template <typename T, size_t N, class AP>
+inline void Vector<T, N, AP>::erase(T* aBegin, T* aEnd) {
+  MOZ_ASSERT(begin() <= aBegin);
+  MOZ_ASSERT(aBegin <= aEnd);
+  MOZ_ASSERT(aEnd <= end());
+  while (aEnd < end()) {
+    *aBegin++ = std::move(*aEnd++);
+  }
+  shrinkBy(aEnd - aBegin);
+}
+
+template <typename T, size_t N, class AP>
+template <typename Pred>
+void Vector<T, N, AP>::eraseIf(Pred aPred) {
+  // remove_if finds the first element to be erased, and then efficiently move-
+  // assigns elements to effectively overwrite elements that satisfy the
+  // predicate. It returns the new end pointer, after which there are only
+  // moved-from elements ready to be destroyed, so we just need to shrink the
+  // vector accordingly.
+  T* newEnd = std::remove_if(begin(), end(),
+                             [&aPred](const T& aT) { return aPred(aT); });
+  MOZ_ASSERT(newEnd <= end());
+  shrinkBy(end() - newEnd);
+}
+
+template <typename T, size_t N, class AP>
+template <typename U>
+void Vector<T, N, AP>::eraseIfEqual(const U& aU) {
+  return eraseIf([&aU](const T& aT) { return aT == aU; });
+}
+
+template <typename T, size_t N, class AP>
+MOZ_ALWAYS_INLINE bool Vector<T, N, AP>::internalEnsureCapacity(
+    size_t aNeeded) {
+  if (mLength + aNeeded > mTail.mCapacity) {
+    if (MOZ_UNLIKELY(!growStorageBy(aNeeded))) {
+      return false;
+    }
+  } else if (!maybeCheckSimulatedOOM(mLength + aNeeded)) {
+    return false;
+  }
+#ifdef DEBUG
+  if (mLength + aNeeded > mTail.mReserved) {
+    mTail.mReserved = mLength + aNeeded;
+  }
+#endif
+  return true;
+}
+
+template <typename T, size_t N, class AP>
+template <typename U>
+MOZ_ALWAYS_INLINE bool Vector<T, N, AP>::append(const U* aInsBegin,
+                                                const U* aInsEnd) {
+  MOZ_REENTRANCY_GUARD_ET_AL;
+  const size_t needed = PointerRangeSize(aInsBegin, aInsEnd);
+  if (!internalEnsureCapacity(needed)) {
+    return false;
+  }
+  internalAppend(aInsBegin, needed);
+  return true;
+}
+
+template <typename T, size_t N, class AP>
+template <typename U>
+MOZ_ALWAYS_INLINE void Vector<T, N, AP>::internalAppend(const U* aInsBegin,
+                                                        size_t aInsLength) {
+  MOZ_ASSERT(mLength + aInsLength <= mTail.mReserved);
+  MOZ_ASSERT(mTail.mReserved <= mTail.mCapacity);
+  Impl::copyConstruct(endNoCheck(), aInsBegin, aInsBegin + aInsLength);
+  mLength += aInsLength;
+}
+
+template <typename T, size_t N, class AP>
+template <typename U>
+MOZ_ALWAYS_INLINE bool Vector<T, N, AP>::moveAppend(U* aInsBegin, U* aInsEnd) {
+  MOZ_REENTRANCY_GUARD_ET_AL;
+  const size_t needed = PointerRangeSize(aInsBegin, aInsEnd);
+  if (!internalEnsureCapacity(needed)) {
+    return false;
+  }
+  internalMoveAppend(aInsBegin, needed);
+  return true;
+}
+
+template <typename T, size_t N, class AP>
+template <typename U>
+MOZ_ALWAYS_INLINE void Vector<T, N, AP>::internalMoveAppend(U* aInsBegin,
+                                                            size_t aInsLength) {
+  MOZ_ASSERT(mLength + aInsLength <= mTail.mReserved);
+  MOZ_ASSERT(mTail.mReserved <= mTail.mCapacity);
+  Impl::moveConstruct(endNoCheck(), aInsBegin, aInsBegin + aInsLength);
+  mLength += aInsLength;
+}
+
+template <typename T, size_t N, class AP>
+template <typename U>
+MOZ_ALWAYS_INLINE bool Vector<T, N, AP>::append(U&& aU) {
+  MOZ_REENTRANCY_GUARD_ET_AL;
+  if (mLength == mTail.mCapacity) {
+    if (MOZ_UNLIKELY(!growStorageBy(1))) {
+      return false;
+    }
+  } else if (!maybeCheckSimulatedOOM(mLength + 1)) {
+    return false;
+  }
+#ifdef DEBUG
+  if (mLength + 1 > mTail.mReserved) {
+    mTail.mReserved = mLength + 1;
+  }
+#endif
+  internalAppend(std::forward<U>(aU));
+  return true;
+}
+
+template <typename T, size_t N, class AP>
+template <typename U, size_t O, class BP>
+MOZ_ALWAYS_INLINE bool Vector<T, N, AP>::appendAll(
+    const Vector<U, O, BP>& aOther) {
+  return append(aOther.begin(), aOther.length());
+}
+
+template <typename T, size_t N, class AP>
+template <typename U, size_t O, class BP>
+MOZ_ALWAYS_INLINE bool Vector<T, N, AP>::appendAll(Vector<U, O, BP>&& aOther) {
+  if (empty() && capacity() < aOther.length()) {
+    *this = std::move(aOther);
+    return true;
+  }
+
+  if (moveAppend(aOther.begin(), aOther.end())) {
+    aOther.clearAndFree();
+    return true;
+  }
+
+  return false;
+}
+
+template <typename T, size_t N, class AP>
+template <class U>
+MOZ_ALWAYS_INLINE bool Vector<T, N, AP>::append(const U* aInsBegin,
+                                                size_t aInsLength) {
+  return append(aInsBegin, aInsBegin + aInsLength);
+}
+
+template <typename T, size_t N, class AP>
+MOZ_ALWAYS_INLINE void Vector<T, N, AP>::popBack() {
+  MOZ_REENTRANCY_GUARD_ET_AL;
+  MOZ_ASSERT(!empty());
+  --mLength;
+  endNoCheck()->~T();
+}
+
+template <typename T, size_t N, class AP>
+MOZ_ALWAYS_INLINE T Vector<T, N, AP>::popCopy() {
+  T ret = back();
+  popBack();
+  return ret;
+}
+
+template <typename T, size_t N, class AP>
+inline T* Vector<T, N, AP>::extractRawBuffer() {
+  MOZ_REENTRANCY_GUARD_ET_AL;
+
+  if (usingInlineStorage()) {
+    return nullptr;
+  }
+
+  T* ret = mBegin;
+  mBegin = inlineStorage();
+  mLength = 0;
+  mTail.mCapacity = kInlineCapacity;
+#ifdef DEBUG
+  mTail.mReserved = 0;
+#endif
+  return ret;
+}
+
+template <typename T, size_t N, class AP>
+inline T* Vector<T, N, AP>::extractOrCopyRawBuffer() {
+  if (T* ret = extractRawBuffer()) {
+    return ret;
+  }
+
+  MOZ_REENTRANCY_GUARD_ET_AL;
+
+  T* copy = this->template pod_malloc<T>(mLength);
+  if (!copy) {
+    return nullptr;
+  }
+
+  Impl::moveConstruct(copy, beginNoCheck(), endNoCheck());
+  Impl::destroy(beginNoCheck(), endNoCheck());
+  mBegin = inlineStorage();
+  mLength = 0;
+  mTail.mCapacity = kInlineCapacity;
+#ifdef DEBUG
+  mTail.mReserved = 0;
+#endif
+  return copy;
+}
+
+template <typename T, size_t N, class AP>
+inline void Vector<T, N, AP>::replaceRawBuffer(T* aP, size_t aLength,
+                                               size_t aCapacity) {
+  MOZ_REENTRANCY_GUARD_ET_AL;
+
+  /* Destroy what we have. */
+  Impl::destroy(beginNoCheck(), endNoCheck());
+  if (!usingInlineStorage()) {
+    this->free_(beginNoCheck(), mTail.mCapacity);
+  }
+
+  /* Take in the new buffer. */
+  if (aCapacity <= kInlineCapacity) {
+    /*
+     * We convert to inline storage if possible, even though aP might
+     * otherwise be acceptable.  Maybe this behaviour should be
+     * specifiable with an argument to this function.
+     */
+    mBegin = inlineStorage();
+    mLength = aLength;
+    mTail.mCapacity = kInlineCapacity;
+    Impl::moveConstruct(mBegin, aP, aP + aLength);
+    Impl::destroy(aP, aP + aLength);
+    this->free_(aP, aCapacity);
+  } else {
+    mBegin = aP;
+    mLength = aLength;
+    mTail.mCapacity = aCapacity;
+  }
+#ifdef DEBUG
+  mTail.mReserved = aCapacity;
+#endif
+}
+
+template <typename T, size_t N, class AP>
+inline void Vector<T, N, AP>::replaceRawBuffer(T* aP, size_t aLength) {
+  replaceRawBuffer(aP, aLength, aLength);
+}
+
+template <typename T, size_t N, class AP>
+inline size_t Vector<T, N, AP>::sizeOfExcludingThis(
+    MallocSizeOf aMallocSizeOf) const {
+  return usingInlineStorage() ? 0 : aMallocSizeOf(beginNoCheck());
+}
+
+template <typename T, size_t N, class AP>
+inline size_t Vector<T, N, AP>::sizeOfIncludingThis(
+    MallocSizeOf aMallocSizeOf) const {
+  return aMallocSizeOf(this) + sizeOfExcludingThis(aMallocSizeOf);
+}
+
+template <typename T, size_t N, class AP>
+inline void Vector<T, N, AP>::swap(Vector& aOther) {
+  static_assert(N == 0, "still need to implement this for N != 0");
+
+  // This only works when inline storage is always empty.
+  if (!usingInlineStorage() && aOther.usingInlineStorage()) {
+    aOther.mBegin = mBegin;
+    mBegin = inlineStorage();
+  } else if (usingInlineStorage() && !aOther.usingInlineStorage()) {
+    mBegin = aOther.mBegin;
+    aOther.mBegin = aOther.inlineStorage();
+  } else if (!usingInlineStorage() && !aOther.usingInlineStorage()) {
+    std::swap(mBegin, aOther.mBegin);
+  } else {
+    // This case is a no-op, since we'd set both to use their inline storage.
+  }
+
+  std::swap(mLength, aOther.mLength);
+  std::swap(mTail.mCapacity, aOther.mTail.mCapacity);
+#ifdef DEBUG
+  std::swap(mTail.mReserved, aOther.mTail.mReserved);
+#endif
+}
+
+}  // namespace mozilla
+
+#endif /* mozilla_Vector_h */