diff --git a/src/prevector.h b/src/prevector.h
index 00afe6166..6ae8d774b 100644
--- a/src/prevector.h
+++ b/src/prevector.h
@@ -1,611 +1,613 @@
 // Copyright (c) 2015-2016 The Bitcoin Core developers
 // Distributed under the MIT software license, see the accompanying
 // file COPYING or http://www.opensource.org/licenses/mit-license.php.
 
 #ifndef BITCOIN_PREVECTOR_H
 #define BITCOIN_PREVECTOR_H
 
 #include <algorithm>
 #include <cassert>
 #include <cstddef>
 #include <cstdint>
 #include <cstdlib>
 #include <cstring>
 #include <type_traits>
 #include <utility>
 
 /**
  * Implements a drop-in replacement for std::vector<T> which stores up to N
  * elements directly (without heap allocation). The types Size and Diff are used
  * to store element counts, and can be any unsigned + signed type.
  *
  * Storage layout is either:
  * - Direct allocation:
  *   - Size _size: the number of used elements (between 0 and N)
  *   - T direct[N]: an array of N elements of type T
  *     (only the first _size are initialized).
  * - Indirect allocation:
  *   - Size _size: the number of used elements plus N + 1
  *   - Size capacity: the number of allocated elements
  *   - T* indirect: a pointer to an array of capacity elements of type T
  *     (only the first _size are initialized).
  *
  * The data type T must be movable by memmove/realloc(). Once we switch to C++,
  * move constructors can be used instead.
  */
 template <unsigned int N, typename T, typename Size = uint32_t,
           typename Diff = int32_t>
 class prevector {
 public:
     typedef Size size_type;
     typedef Diff difference_type;
     typedef T value_type;
     typedef value_type &reference;
     typedef const value_type &const_reference;
     typedef value_type *pointer;
     typedef const value_type *const_pointer;
 
     class iterator {
         T *ptr;
 
     public:
         typedef Diff difference_type;
         typedef T value_type;
         typedef T *pointer;
         typedef T &reference;
         typedef std::random_access_iterator_tag iterator_category;
         iterator() : ptr(nullptr) {}
         iterator(T *ptr_) : ptr(ptr_) {}
         T &operator*() const { return *ptr; }
         T *operator->() const { return ptr; }
         T &operator[](size_type pos) { return ptr[pos]; }
         const T &operator[](size_type pos) const { return ptr[pos]; }
         iterator &operator++() {
             ptr++;
             return *this;
         }
         iterator &operator--() {
             ptr--;
             return *this;
         }
         iterator operator++(int) {
             iterator copy(*this);
             ++(*this);
             return copy;
         }
         iterator operator--(int) {
             iterator copy(*this);
             --(*this);
             return copy;
         }
         difference_type friend operator-(iterator a, iterator b) {
             return (&(*a) - &(*b));
         }
         iterator operator+(size_type n) { return iterator(ptr + n); }
         iterator &operator+=(size_type n) {
             ptr += n;
             return *this;
         }
         iterator operator-(size_type n) { return iterator(ptr - n); }
         iterator &operator-=(size_type n) {
             ptr -= n;
             return *this;
         }
         bool operator==(iterator x) const { return ptr == x.ptr; }
         bool operator!=(iterator x) const { return ptr != x.ptr; }
         bool operator>=(iterator x) const { return ptr >= x.ptr; }
         bool operator<=(iterator x) const { return ptr <= x.ptr; }
         bool operator>(iterator x) const { return ptr > x.ptr; }
         bool operator<(iterator x) const { return ptr < x.ptr; }
     };
 
     class reverse_iterator {
         T *ptr;
 
     public:
         typedef Diff difference_type;
         typedef T value_type;
         typedef T *pointer;
         typedef T &reference;
         typedef std::bidirectional_iterator_tag iterator_category;
         reverse_iterator() : ptr(nullptr) {}
         reverse_iterator(T *ptr_) : ptr(ptr_) {}
         T &operator*() { return *ptr; }
         const T &operator*() const { return *ptr; }
         T *operator->() { return ptr; }
         const T *operator->() const { return ptr; }
         reverse_iterator &operator--() {
             ptr++;
             return *this;
         }
         reverse_iterator &operator++() {
             ptr--;
             return *this;
         }
         reverse_iterator operator++(int) {
             reverse_iterator copy(*this);
             ++(*this);
             return copy;
         }
         reverse_iterator operator--(int) {
             reverse_iterator copy(*this);
             --(*this);
             return copy;
         }
         bool operator==(reverse_iterator x) const { return ptr == x.ptr; }
         bool operator!=(reverse_iterator x) const { return ptr != x.ptr; }
     };
 
     class const_iterator {
         const T *ptr;
 
     public:
         typedef Diff difference_type;
         typedef const T value_type;
         typedef const T *pointer;
         typedef const T &reference;
         typedef std::random_access_iterator_tag iterator_category;
         const_iterator() : ptr(nullptr) {}
         const_iterator(const T *ptr_) : ptr(ptr_) {}
         const_iterator(iterator x) : ptr(&(*x)) {}
         const T &operator*() const { return *ptr; }
         const T *operator->() const { return ptr; }
         const T &operator[](size_type pos) const { return ptr[pos]; }
         const_iterator &operator++() {
             ptr++;
             return *this;
         }
         const_iterator &operator--() {
             ptr--;
             return *this;
         }
         const_iterator operator++(int) {
             const_iterator copy(*this);
             ++(*this);
             return copy;
         }
         const_iterator operator--(int) {
             const_iterator copy(*this);
             --(*this);
             return copy;
         }
         difference_type friend operator-(const_iterator a, const_iterator b) {
             return (&(*a) - &(*b));
         }
         const_iterator operator+(size_type n) {
             return const_iterator(ptr + n);
         }
         const_iterator &operator+=(size_type n) {
             ptr += n;
             return *this;
         }
         const_iterator operator-(size_type n) {
             return const_iterator(ptr - n);
         }
         const_iterator &operator-=(size_type n) {
             ptr -= n;
             return *this;
         }
         bool operator==(const_iterator x) const { return ptr == x.ptr; }
         bool operator!=(const_iterator x) const { return ptr != x.ptr; }
         bool operator>=(const_iterator x) const { return ptr >= x.ptr; }
         bool operator<=(const_iterator x) const { return ptr <= x.ptr; }
         bool operator>(const_iterator x) const { return ptr > x.ptr; }
         bool operator<(const_iterator x) const { return ptr < x.ptr; }
     };
 
     class const_reverse_iterator {
         const T *ptr;
 
     public:
         typedef Diff difference_type;
         typedef const T value_type;
         typedef const T *pointer;
         typedef const T &reference;
         typedef std::bidirectional_iterator_tag iterator_category;
         const_reverse_iterator() : ptr(nullptr) {}
         const_reverse_iterator(const T *ptr_) : ptr(ptr_) {}
         const_reverse_iterator(reverse_iterator x) : ptr(&(*x)) {}
         const T &operator*() const { return *ptr; }
         const T *operator->() const { return ptr; }
         const_reverse_iterator &operator--() {
             ptr++;
             return *this;
         }
         const_reverse_iterator &operator++() {
             ptr--;
             return *this;
         }
         const_reverse_iterator operator++(int) {
             const_reverse_iterator copy(*this);
             ++(*this);
             return copy;
         }
         const_reverse_iterator operator--(int) {
             const_reverse_iterator copy(*this);
             --(*this);
             return copy;
         }
         bool operator==(const_reverse_iterator x) const { return ptr == x.ptr; }
         bool operator!=(const_reverse_iterator x) const { return ptr != x.ptr; }
     };
 
 private:
 #pragma pack(push, 1)
     union direct_or_indirect {
         char direct[sizeof(T) * N];
         struct {
             char *indirect;
             size_type capacity;
         };
     };
 #pragma pack(pop)
     alignas(char *) direct_or_indirect _union = {};
     size_type _size = 0;
 
     static_assert(alignof(char *) % alignof(size_type) == 0 &&
                       sizeof(char *) % alignof(size_type) == 0,
                   "size_type cannot have more restrictive alignment "
                   "requirement than pointer");
     static_assert(alignof(char *) % alignof(T) == 0,
                   "value_type T cannot have more restrictive alignment "
                   "requirement than pointer");
 
     T *direct_ptr(difference_type pos) {
         return reinterpret_cast<T *>(_union.direct) + pos;
     }
     const T *direct_ptr(difference_type pos) const {
         return reinterpret_cast<const T *>(_union.direct) + pos;
     }
     T *indirect_ptr(difference_type pos) {
         return reinterpret_cast<T *>(_union.indirect) + pos;
     }
     const T *indirect_ptr(difference_type pos) const {
         return reinterpret_cast<const T *>(_union.indirect) + pos;
     }
     bool is_direct() const { return _size <= N; }
 
     void change_capacity(size_type new_capacity) {
         if (new_capacity <= N) {
             if (!is_direct()) {
                 T *indirect = indirect_ptr(0);
                 T *src = indirect;
                 T *dst = direct_ptr(0);
                 memcpy(dst, src, size() * sizeof(T));
                 free(indirect);
                 _size -= N + 1;
             }
         } else {
             if (!is_direct()) {
                 // FIXME: Because malloc/realloc here won't call new_handler if
                 // allocation fails, assert success. These should instead use an
                 // allocator or new/delete so that handlers are called as
                 // necessary, but performance would be slightly degraded by
                 // doing so.
                 _union.indirect = static_cast<char *>(realloc(
                     _union.indirect, ((size_t)sizeof(T)) * new_capacity));
                 assert(_union.indirect);
                 _union.capacity = new_capacity;
             } else {
                 char *new_indirect = static_cast<char *>(
                     malloc(((size_t)sizeof(T)) * new_capacity));
                 assert(new_indirect);
                 T *src = direct_ptr(0);
                 T *dst = reinterpret_cast<T *>(new_indirect);
                 memcpy(dst, src, size() * sizeof(T));
                 _union.indirect = new_indirect;
                 _union.capacity = new_capacity;
                 _size += N + 1;
             }
         }
     }
 
     T *item_ptr(difference_type pos) {
         return is_direct() ? direct_ptr(pos) : indirect_ptr(pos);
     }
     const T *item_ptr(difference_type pos) const {
         return is_direct() ? direct_ptr(pos) : indirect_ptr(pos);
     }
 
     void fill(T *dst, ptrdiff_t count, const T &value = T{}) {
         std::fill_n(dst, count, value);
     }
 
     template <typename InputIterator>
     void fill(T *dst, InputIterator first, InputIterator last) {
         while (first != last) {
             new (static_cast<void *>(dst)) T(*first);
             ++dst;
             ++first;
         }
     }
 
 public:
     void assign(size_type n, const T &val) {
         clear();
         if (capacity() < n) {
             change_capacity(n);
         }
         _size += n;
         fill(item_ptr(0), n, val);
     }
 
     template <typename InputIterator>
     void assign(InputIterator first, InputIterator last) {
         size_type n = last - first;
         clear();
         if (capacity() < n) {
             change_capacity(n);
         }
         _size += n;
         fill(item_ptr(0), first, last);
     }
 
     prevector() {}
 
     explicit prevector(size_type n) { resize(n); }
 
     explicit prevector(size_type n, const T &val) {
         change_capacity(n);
         _size += n;
         fill(item_ptr(0), n, val);
     }
 
     template <typename InputIterator>
     prevector(InputIterator first, InputIterator last) {
         size_type n = last - first;
         change_capacity(n);
         _size += n;
         fill(item_ptr(0), first, last);
     }
 
     prevector(const prevector<N, T, Size, Diff> &other) {
         size_type n = other.size();
         change_capacity(n);
         _size += n;
         fill(item_ptr(0), other.begin(), other.end());
     }
 
     prevector(prevector<N, T, Size, Diff> &&other) { swap(other); }
 
     prevector &operator=(const prevector<N, T, Size, Diff> &other) {
         if (&other == this) {
             return *this;
         }
         assign(other.begin(), other.end());
         return *this;
     }
 
     prevector &operator=(prevector<N, T, Size, Diff> &&other) {
         swap(other);
         return *this;
     }
 
     size_type size() const { return is_direct() ? _size : _size - N - 1; }
 
     bool empty() const { return size() == 0; }
 
     iterator begin() { return iterator(item_ptr(0)); }
     const_iterator begin() const { return const_iterator(item_ptr(0)); }
     iterator end() { return iterator(item_ptr(size())); }
     const_iterator end() const { return const_iterator(item_ptr(size())); }
 
     reverse_iterator rbegin() { return reverse_iterator(item_ptr(size() - 1)); }
     const_reverse_iterator rbegin() const {
         return const_reverse_iterator(item_ptr(size() - 1));
     }
     reverse_iterator rend() { return reverse_iterator(item_ptr(-1)); }
     const_reverse_iterator rend() const {
         return const_reverse_iterator(item_ptr(-1));
     }
 
     size_t capacity() const {
         if (is_direct()) {
             return N;
         } else {
             return _union.capacity;
         }
     }
 
     T &operator[](size_type pos) { return *item_ptr(pos); }
 
     const T &operator[](size_type pos) const { return *item_ptr(pos); }
 
     void resize(size_type new_size) {
         size_type cur_size = size();
         if (cur_size == new_size) {
             return;
         }
         if (cur_size > new_size) {
             erase(item_ptr(new_size), end());
             return;
         }
         if (new_size > capacity()) {
             change_capacity(new_size);
         }
         ptrdiff_t increase = new_size - cur_size;
         fill(item_ptr(cur_size), increase);
         _size += increase;
     }
 
     void reserve(size_type new_capacity) {
         if (new_capacity > capacity()) {
             change_capacity(new_capacity);
         }
     }
 
     void shrink_to_fit() { change_capacity(size()); }
 
     void clear() { resize(0); }
 
     iterator insert(iterator pos, const T &value) {
         size_type p = pos - begin();
         size_type new_size = size() + 1;
         if (capacity() < new_size) {
             change_capacity(new_size + (new_size >> 1));
         }
         T *ptr = item_ptr(p);
         memmove(ptr + 1, ptr, (size() - p) * sizeof(T));
         _size++;
         new (static_cast<void *>(ptr)) T(value);
         return iterator(ptr);
     }
 
     void insert(iterator pos, size_type count, const T &value) {
         size_type p = pos - begin();
         size_type new_size = size() + count;
         if (capacity() < new_size) {
             change_capacity(new_size + (new_size >> 1));
         }
         T *ptr = item_ptr(p);
         memmove(ptr + count, ptr, (size() - p) * sizeof(T));
         _size += count;
         fill(item_ptr(p), count, value);
     }
 
     template <typename InputIterator>
     void insert(iterator pos, InputIterator first, InputIterator last) {
         size_type p = pos - begin();
         difference_type count = last - first;
         size_type new_size = size() + count;
         if (capacity() < new_size) {
             change_capacity(new_size + (new_size >> 1));
         }
         T *ptr = item_ptr(p);
         memmove(ptr + count, ptr, (size() - p) * sizeof(T));
         _size += count;
         fill(ptr, first, last);
     }
 
     inline void resize_uninitialized(size_type new_size) {
         // resize_uninitialized changes the size of the prevector but does not
         // initialize it. If size < new_size, the added elements must be
         // initialized explicitly.
         if (capacity() < new_size) {
             change_capacity(new_size);
             _size += new_size - size();
             return;
         }
         if (new_size < size()) {
             erase(item_ptr(new_size), end());
         } else {
             _size += new_size - size();
         }
     }
 
     iterator erase(iterator pos) { return erase(pos, pos + 1); }
 
     iterator erase(iterator first, iterator last) {
         // Erase is not allowed to the change the object's capacity. That means
         // that when starting with an indirectly allocated prevector with
         // size and capacity > N, the result may be a still indirectly allocated
         // prevector with size <= N and capacity > N. A shrink_to_fit() call is
         // necessary to switch to the (more efficient) directly allocated
         // representation (with capacity N and size <= N).
         iterator p = first;
         char *endp = (char *)&(*end());
         if (!std::is_trivially_destructible<T>::value) {
             while (p != last) {
                 (*p).~T();
                 _size--;
                 ++p;
             }
         } else {
             _size -= last - p;
         }
         memmove(&(*first), &(*last), endp - ((char *)(&(*last))));
         return first;
     }
 
-    void push_back(const T &value) {
+    template <typename... Args> void emplace_back(Args &&... args) {
         size_type new_size = size() + 1;
         if (capacity() < new_size) {
             change_capacity(new_size + (new_size >> 1));
         }
-        new (item_ptr(size())) T(value);
+        new (item_ptr(size())) T(std::forward<Args>(args)...);
         _size++;
     }
 
+    void push_back(const T &value) { emplace_back(value); }
+
     void pop_back() { erase(end() - 1, end()); }
 
     T &front() { return *item_ptr(0); }
 
     const T &front() const { return *item_ptr(0); }
 
     T &back() { return *item_ptr(size() - 1); }
 
     const T &back() const { return *item_ptr(size() - 1); }
 
     void swap(prevector<N, T, Size, Diff> &other) {
         std::swap(_union, other._union);
         std::swap(_size, other._size);
     }
 
     ~prevector() {
         if (!std::is_trivially_destructible<T>::value) {
             clear();
         }
         if (!is_direct()) {
             free(_union.indirect);
             _union.indirect = nullptr;
         }
     }
 
     bool operator==(const prevector<N, T, Size, Diff> &other) const {
         if (other.size() != size()) {
             return false;
         }
         const_iterator b1 = begin();
         const_iterator b2 = other.begin();
         const_iterator e1 = end();
         while (b1 != e1) {
             if ((*b1) != (*b2)) {
                 return false;
             }
             ++b1;
             ++b2;
         }
         return true;
     }
 
     bool operator!=(const prevector<N, T, Size, Diff> &other) const {
         return !(*this == other);
     }
 
     bool operator<(const prevector<N, T, Size, Diff> &other) const {
         if (size() < other.size()) {
             return true;
         }
         if (size() > other.size()) {
             return false;
         }
         const_iterator b1 = begin();
         const_iterator b2 = other.begin();
         const_iterator e1 = end();
         while (b1 != e1) {
             if ((*b1) < (*b2)) {
                 return true;
             }
             if ((*b2) < (*b1)) {
                 return false;
             }
             ++b1;
             ++b2;
         }
         return false;
     }
 
     size_t allocated_memory() const {
         if (is_direct()) {
             return 0;
         } else {
             return ((size_t)(sizeof(T))) * _union.capacity;
         }
     }
 
     value_type *data() { return item_ptr(0); }
 
     const value_type *data() const { return item_ptr(0); }
 };
 
 #endif // BITCOIN_PREVECTOR_H
diff --git a/src/serialize.h b/src/serialize.h
index e173589da..9851d14c0 100644
--- a/src/serialize.h
+++ b/src/serialize.h
@@ -1,1179 +1,1180 @@
 // Copyright (c) 2009-2010 Satoshi Nakamoto
 // Copyright (c) 2009-2016 The Bitcoin Core developers
 // Distributed under the MIT software license, see the accompanying
 // file COPYING or http://www.opensource.org/licenses/mit-license.php.
 
 #ifndef BITCOIN_SERIALIZE_H
 #define BITCOIN_SERIALIZE_H
 
 #include <compat/endian.h>
 #include <prevector.h>
 #include <span.h>
 
 #include <algorithm>
 #include <array>
 #include <cstdint>
 #include <cstring>
 #include <ios>
 #include <limits>
 #include <map>
 #include <memory>
 #include <set>
 #include <string>
 #include <utility>
 #include <vector>
 
 static const uint64_t MAX_SIZE = 0x02000000;
 
 /**
  * Maximum amount of memory (in bytes) to allocate at once when deserializing
  * vectors.
  */
 static const unsigned int MAX_VECTOR_ALLOCATE = 5000000;
 
 /**
  * Dummy data type to identify deserializing constructors.
  *
  * By convention, a constructor of a type T with signature
  *
  *   template <typename Stream> T::T(deserialize_type, Stream& s)
  *
  * is a deserializing constructor, which builds the type by deserializing it
  * from s. If T contains const fields, this is likely the only way to do so.
  */
 struct deserialize_type {};
 constexpr deserialize_type deserialize{};
 
 /**
  * Used to bypass the rule against non-const reference to temporary
  * where it makes sense with wrappers.
  */
 template <typename T> inline T &REF(const T &val) {
     return const_cast<T &>(val);
 }
 
 /**
  * Used to acquire a non-const pointer "this" to generate bodies of const
  * serialization operations from a template
  */
 template <typename T> inline T *NCONST_PTR(const T *val) {
     return const_cast<T *>(val);
 }
 
 //! Safely convert odd char pointer types to standard ones.
 inline char *CharCast(char *c) {
     return c;
 }
 inline char *CharCast(uint8_t *c) {
     return (char *)c;
 }
 inline const char *CharCast(const char *c) {
     return c;
 }
 inline const char *CharCast(const uint8_t *c) {
     return (const char *)c;
 }
 
 /**
  * Lowest-level serialization and conversion.
  * @note Sizes of these types are verified in the tests
  */
 template <typename Stream> inline void ser_writedata8(Stream &s, uint8_t obj) {
     s.write((char *)&obj, 1);
 }
 template <typename Stream>
 inline void ser_writedata16(Stream &s, uint16_t obj) {
     obj = htole16(obj);
     s.write((char *)&obj, 2);
 }
 template <typename Stream>
 inline void ser_writedata16be(Stream &s, uint16_t obj) {
     obj = htobe16(obj);
     s.write((char *)&obj, 2);
 }
 template <typename Stream>
 inline void ser_writedata32(Stream &s, uint32_t obj) {
     obj = htole32(obj);
     s.write((char *)&obj, 4);
 }
 template <typename Stream>
 inline void ser_writedata32be(Stream &s, uint32_t obj) {
     obj = htobe32(obj);
     s.write((char *)&obj, 4);
 }
 template <typename Stream>
 inline void ser_writedata64(Stream &s, uint64_t obj) {
     obj = htole64(obj);
     s.write((char *)&obj, 8);
 }
 template <typename Stream> inline uint8_t ser_readdata8(Stream &s) {
     uint8_t obj;
     s.read((char *)&obj, 1);
     return obj;
 }
 template <typename Stream> inline uint16_t ser_readdata16(Stream &s) {
     uint16_t obj;
     s.read((char *)&obj, 2);
     return le16toh(obj);
 }
 template <typename Stream> inline uint16_t ser_readdata16be(Stream &s) {
     uint16_t obj;
     s.read((char *)&obj, 2);
     return be16toh(obj);
 }
 template <typename Stream> inline uint32_t ser_readdata32(Stream &s) {
     uint32_t obj;
     s.read((char *)&obj, 4);
     return le32toh(obj);
 }
 template <typename Stream> inline uint32_t ser_readdata32be(Stream &s) {
     uint32_t obj;
     s.read((char *)&obj, 4);
     return be32toh(obj);
 }
 template <typename Stream> inline uint64_t ser_readdata64(Stream &s) {
     uint64_t obj;
     s.read((char *)&obj, 8);
     return le64toh(obj);
 }
 inline uint64_t ser_double_to_uint64(double x) {
     uint64_t tmp;
     std::memcpy(&tmp, &x, sizeof(x));
     static_assert(sizeof(tmp) == sizeof(x),
                   "double and uint64_t assumed to have the same size");
     return tmp;
 }
 inline uint32_t ser_float_to_uint32(float x) {
     uint32_t tmp;
     std::memcpy(&tmp, &x, sizeof(x));
     static_assert(sizeof(tmp) == sizeof(x),
                   "float and uint32_t assumed to have the same size");
     return tmp;
 }
 inline double ser_uint64_to_double(uint64_t y) {
     double tmp;
     std::memcpy(&tmp, &y, sizeof(y));
     static_assert(sizeof(tmp) == sizeof(y),
                   "double and uint64_t assumed to have the same size");
     return tmp;
 }
 inline float ser_uint32_to_float(uint32_t y) {
     float tmp;
     std::memcpy(&tmp, &y, sizeof(y));
     static_assert(sizeof(tmp) == sizeof(y),
                   "float and uint32_t assumed to have the same size");
     return tmp;
 }
 
 /////////////////////////////////////////////////////////////////
 //
 // Templates for serializing to anything that looks like a stream,
 // i.e. anything that supports .read(char*, size_t) and .write(char*, size_t)
 //
 class CSizeComputer;
 
 enum {
     // primary actions
     SER_NETWORK = (1 << 0),
     SER_DISK = (1 << 1),
     SER_GETHASH = (1 << 2),
 };
 
 //! Convert the reference base type to X, without changing constness or
 //! reference type.
 template <typename X> X &ReadWriteAsHelper(X &x) {
     return x;
 }
 template <typename X> const X &ReadWriteAsHelper(const X &x) {
     return x;
 }
 
 #define READWRITE(...) (::SerReadWriteMany(s, ser_action, __VA_ARGS__))
 #define READWRITEAS(type, obj)                                                 \
     (::SerReadWriteMany(s, ser_action, ReadWriteAsHelper<type>(obj)))
 
 /**
  * Implement three methods for serializable objects. These are actually wrappers
  * over "SerializationOp" template, which implements the body of each class'
  * serialization code. Adding "ADD_SERIALIZE_METHODS" in the body of the class
  * causes these wrappers to be added as members.
  */
 #define ADD_SERIALIZE_METHODS                                                  \
     template <typename Stream> void Serialize(Stream &s) const {               \
         NCONST_PTR(this)->SerializationOp(s, CSerActionSerialize());           \
     }                                                                          \
     template <typename Stream> void Unserialize(Stream &s) {                   \
         SerializationOp(s, CSerActionUnserialize());                           \
     }
 
 /**
  * Implement the Ser and Unser methods needed for implementing a formatter
  * (see Using below).
  *
  * Both Ser and Unser are delegated to a single static method SerializationOps,
  * which is polymorphic in the serialized/deserialized type (allowing it to be
  * const when serializing, and non-const when deserializing).
  *
  * Example use:
  *   struct FooFormatter {
  *     FORMATTER_METHODS(Class, obj) { READWRITE(obj.val1, VARINT(obj.val2)); }
  *   }
  * would define a class FooFormatter that defines a serialization of Class
  * objects consisting of serializing its val1 member using the default
  * serialization, and its val2 member using VARINT serialization. That
  * FooFormatter can then be used in statements like
  *   READWRITE(Using<FooFormatter>(obj.bla)).
  */
 #define FORMATTER_METHODS(cls, obj)                                            \
     template <typename Stream> static void Ser(Stream &s, const cls &obj) {    \
         SerializationOps(obj, s, CSerActionSerialize());                       \
     }                                                                          \
     template <typename Stream> static void Unser(Stream &s, cls &obj) {        \
         SerializationOps(obj, s, CSerActionUnserialize());                     \
     }                                                                          \
     template <typename Stream, typename Type, typename Operation>              \
     static inline void SerializationOps(Type &obj, Stream &s,                  \
                                         Operation ser_action)
 
 /**
  * Implement the Serialize and Unserialize methods by delegating to a
  * single templated static method that takes the to-be-(de)serialized
  * object as a parameter. This approach has the advantage that the
  * constness of the object becomes a template parameter, and thus
  * allows a single implementation that sees the object as const for
  * serializing and non-const for deserializing, without casts.
  */
 #define SERIALIZE_METHODS(cls, obj)                                            \
     template <typename Stream> void Serialize(Stream &s) const {               \
         static_assert(std::is_same<const cls &, decltype(*this)>::value,       \
                       "Serialize type mismatch");                              \
         Ser(s, *this);                                                         \
     }                                                                          \
     template <typename Stream> void Unserialize(Stream &s) {                   \
         static_assert(std::is_same<cls &, decltype(*this)>::value,             \
                       "Unserialize type mismatch");                            \
         Unser(s, *this);                                                       \
     }                                                                          \
     FORMATTER_METHODS(cls, obj)
 
 #ifndef CHAR_EQUALS_INT8
 // TODO Get rid of bare char
 template <typename Stream> inline void Serialize(Stream &s, char a) {
     ser_writedata8(s, a);
 }
 #endif
 template <typename Stream> inline void Serialize(Stream &s, int8_t a) {
     ser_writedata8(s, a);
 }
 template <typename Stream> inline void Serialize(Stream &s, uint8_t a) {
     ser_writedata8(s, a);
 }
 template <typename Stream> inline void Serialize(Stream &s, int16_t a) {
     ser_writedata16(s, a);
 }
 template <typename Stream> inline void Serialize(Stream &s, uint16_t a) {
     ser_writedata16(s, a);
 }
 template <typename Stream> inline void Serialize(Stream &s, int32_t a) {
     ser_writedata32(s, a);
 }
 template <typename Stream> inline void Serialize(Stream &s, uint32_t a) {
     ser_writedata32(s, a);
 }
 template <typename Stream> inline void Serialize(Stream &s, int64_t a) {
     ser_writedata64(s, a);
 }
 template <typename Stream> inline void Serialize(Stream &s, uint64_t a) {
     ser_writedata64(s, a);
 }
 template <typename Stream> inline void Serialize(Stream &s, float a) {
     ser_writedata32(s, ser_float_to_uint32(a));
 }
 template <typename Stream> inline void Serialize(Stream &s, double a) {
     ser_writedata64(s, ser_double_to_uint64(a));
 }
 template <typename Stream, size_t N>
 inline void Serialize(Stream &s, const int8_t (&a)[N]) {
     s.write(a, N);
 }
 template <typename Stream, size_t N>
 inline void Serialize(Stream &s, const uint8_t (&a)[N]) {
     s.write(CharCast(a), N);
 }
 template <typename Stream, size_t N>
 inline void Serialize(Stream &s, const std::array<int8_t, N> &a) {
     s.write(a.data(), N);
 }
 template <typename Stream, size_t N>
 inline void Serialize(Stream &s, const std::array<uint8_t, N> &a) {
     s.write(CharCast(a.data()), N);
 }
 #ifndef CHAR_EQUALS_INT8
 // TODO Get rid of bare char
 template <typename Stream> inline void Unserialize(Stream &s, char &a) {
     a = ser_readdata8(s);
 }
 template <typename Stream, size_t N>
 inline void Serialize(Stream &s, const char (&a)[N]) {
     s.write(a, N);
 }
 template <typename Stream, size_t N>
 inline void Serialize(Stream &s, const std::array<char, N> &a) {
     s.write(a.data(), N);
 }
 #endif
 template <typename Stream>
 inline void Serialize(Stream &s, const Span<const uint8_t> &span) {
     s.write(CharCast(span.data()), span.size());
 }
 template <typename Stream>
 inline void Serialize(Stream &s, const Span<uint8_t> &span) {
     s.write(CharCast(span.data()), span.size());
 }
 template <typename Stream> inline void Unserialize(Stream &s, int8_t &a) {
     a = ser_readdata8(s);
 }
 template <typename Stream> inline void Unserialize(Stream &s, uint8_t &a) {
     a = ser_readdata8(s);
 }
 template <typename Stream> inline void Unserialize(Stream &s, int16_t &a) {
     a = ser_readdata16(s);
 }
 template <typename Stream> inline void Unserialize(Stream &s, uint16_t &a) {
     a = ser_readdata16(s);
 }
 template <typename Stream> inline void Unserialize(Stream &s, int32_t &a) {
     a = ser_readdata32(s);
 }
 template <typename Stream> inline void Unserialize(Stream &s, uint32_t &a) {
     a = ser_readdata32(s);
 }
 template <typename Stream> inline void Unserialize(Stream &s, int64_t &a) {
     a = ser_readdata64(s);
 }
 template <typename Stream> inline void Unserialize(Stream &s, uint64_t &a) {
     a = ser_readdata64(s);
 }
 template <typename Stream> inline void Unserialize(Stream &s, float &a) {
     a = ser_uint32_to_float(ser_readdata32(s));
 }
 template <typename Stream> inline void Unserialize(Stream &s, double &a) {
     a = ser_uint64_to_double(ser_readdata64(s));
 }
 template <typename Stream, size_t N>
 inline void Unserialize(Stream &s, int8_t (&a)[N]) {
     s.read(a, N);
 }
 template <typename Stream, size_t N>
 inline void Unserialize(Stream &s, uint8_t (&a)[N]) {
     s.read(CharCast(a), N);
 }
 template <typename Stream, size_t N>
 inline void Unserialize(Stream &s, std::array<int8_t, N> &a) {
     s.read(a.data(), N);
 }
 template <typename Stream, size_t N>
 inline void Unserialize(Stream &s, std::array<uint8_t, N> &a) {
     s.read(CharCast(a.data()), N);
 }
 #ifndef CHAR_EQUALS_INT8
 template <typename Stream, size_t N>
 inline void Unserialize(Stream &s, char (&a)[N]) {
     s.read(CharCast(a), N);
 }
 template <typename Stream, size_t N>
 inline void Unserialize(Stream &s, std::array<char, N> &a) {
     s.read(CharCast(a.data()), N);
 }
 #endif
 
 template <typename Stream> inline void Serialize(Stream &s, bool a) {
     char f = a;
     ser_writedata8(s, f);
 }
 template <typename Stream> inline void Unserialize(Stream &s, bool &a) {
     char f = ser_readdata8(s);
     a = f;
 }
 template <typename Stream>
 inline void Unserialize(Stream &s, Span<uint8_t> &span) {
     s.read(CharCast(span.data()), span.size());
 }
 
 /**
  * Compact Size
  * size <  253        -- 1 byte
  * size <= USHRT_MAX  -- 3 bytes  (253 + 2 bytes)
  * size <= UINT_MAX   -- 5 bytes  (254 + 4 bytes)
  * size >  UINT_MAX   -- 9 bytes  (255 + 8 bytes)
  */
 inline uint32_t GetSizeOfCompactSize(uint64_t nSize) {
     if (nSize < 253) {
         return sizeof(uint8_t);
     }
     if (nSize <= std::numeric_limits<uint16_t>::max()) {
         return sizeof(uint8_t) + sizeof(uint16_t);
     }
     if (nSize <= std::numeric_limits<uint32_t>::max()) {
         return sizeof(uint8_t) + sizeof(uint32_t);
     }
 
     return sizeof(uint8_t) + sizeof(uint64_t);
 }
 
 inline void WriteCompactSize(CSizeComputer &os, uint64_t nSize);
 
 template <typename Stream> void WriteCompactSize(Stream &os, uint64_t nSize) {
     if (nSize < 253) {
         ser_writedata8(os, nSize);
     } else if (nSize <= std::numeric_limits<uint16_t>::max()) {
         ser_writedata8(os, 253);
         ser_writedata16(os, nSize);
     } else if (nSize <= std::numeric_limits<uint32_t>::max()) {
         ser_writedata8(os, 254);
         ser_writedata32(os, nSize);
     } else {
         ser_writedata8(os, 255);
         ser_writedata64(os, nSize);
     }
     return;
 }
 
 template <typename Stream> uint64_t ReadCompactSize(Stream &is) {
     uint8_t chSize = ser_readdata8(is);
     uint64_t nSizeRet = 0;
     if (chSize < 253) {
         nSizeRet = chSize;
     } else if (chSize == 253) {
         nSizeRet = ser_readdata16(is);
         if (nSizeRet < 253) {
             throw std::ios_base::failure("non-canonical ReadCompactSize()");
         }
     } else if (chSize == 254) {
         nSizeRet = ser_readdata32(is);
         if (nSizeRet < 0x10000u) {
             throw std::ios_base::failure("non-canonical ReadCompactSize()");
         }
     } else {
         nSizeRet = ser_readdata64(is);
         if (nSizeRet < 0x100000000ULL) {
             throw std::ios_base::failure("non-canonical ReadCompactSize()");
         }
     }
     if (nSizeRet > MAX_SIZE) {
         throw std::ios_base::failure("ReadCompactSize(): size too large");
     }
     return nSizeRet;
 }
 
 /**
  * Variable-length integers: bytes are a MSB base-128 encoding of the number.
  * The high bit in each byte signifies whether another digit follows. To make
  * sure the encoding is one-to-one, one is subtracted from all but the last
  * digit. Thus, the byte sequence a[] with length len, where all but the last
  * byte has bit 128 set, encodes the number:
  *
  *  (a[len-1] & 0x7F) + sum(i=1..len-1, 128^i*((a[len-i-1] & 0x7F)+1))
  *
  * Properties:
  * * Very small (0-127: 1 byte, 128-16511: 2 bytes, 16512-2113663: 3 bytes)
  * * Every integer has exactly one encoding
  * * Encoding does not depend on size of original integer type
  * * No redundancy: every (infinite) byte sequence corresponds to a list
  *   of encoded integers.
  *
  * 0:         [0x00]  256:        [0x81 0x00]
  * 1:         [0x01]  16383:      [0xFE 0x7F]
  * 127:       [0x7F]  16384:      [0xFF 0x00]
  * 128:  [0x80 0x00]  16511:      [0xFF 0x7F]
  * 255:  [0x80 0x7F]  65535: [0x82 0xFE 0x7F]
  * 2^32:           [0x8E 0xFE 0xFE 0xFF 0x00]
  */
 
 /**
  * Mode for encoding VarInts.
  *
  * Currently there is no support for signed encodings. The default mode will not
  * compile with signed values, and the legacy "nonnegative signed" mode will
  * accept signed values, but improperly encode and decode them if they are
  * negative. In the future, the DEFAULT mode could be extended to support
  * negative numbers in a backwards compatible way, and additional modes could be
  * added to support different varint formats (e.g. zigzag encoding).
  */
 enum class VarIntMode { DEFAULT, NONNEGATIVE_SIGNED };
 
 template <VarIntMode Mode, typename I> struct CheckVarIntMode {
     constexpr CheckVarIntMode() {
         static_assert(Mode != VarIntMode::DEFAULT || std::is_unsigned<I>::value,
                       "Unsigned type required with mode DEFAULT.");
         static_assert(Mode != VarIntMode::NONNEGATIVE_SIGNED ||
                           std::is_signed<I>::value,
                       "Signed type required with mode NONNEGATIVE_SIGNED.");
     }
 };
 
 template <VarIntMode Mode, typename I>
 inline unsigned int GetSizeOfVarInt(I n) {
     CheckVarIntMode<Mode, I>();
     int nRet = 0;
     while (true) {
         nRet++;
         if (n <= 0x7F) {
             return nRet;
         }
         n = (n >> 7) - 1;
     }
 }
 
 template <typename I> inline void WriteVarInt(CSizeComputer &os, I n);
 
 template <typename Stream, VarIntMode Mode, typename I>
 void WriteVarInt(Stream &os, I n) {
     CheckVarIntMode<Mode, I>();
     uint8_t tmp[(sizeof(n) * 8 + 6) / 7];
     int len = 0;
     while (true) {
         tmp[len] = (n & 0x7F) | (len ? 0x80 : 0x00);
         if (n <= 0x7F) {
             break;
         }
         n = (n >> 7) - 1;
         len++;
     }
     do {
         ser_writedata8(os, tmp[len]);
     } while (len--);
 }
 
 template <typename Stream, VarIntMode Mode, typename I>
 I ReadVarInt(Stream &is) {
     CheckVarIntMode<Mode, I>();
     I n = 0;
     while (true) {
         uint8_t chData = ser_readdata8(is);
         if (n > (std::numeric_limits<I>::max() >> 7)) {
             throw std::ios_base::failure("ReadVarInt(): size too large");
         }
         n = (n << 7) | (chData & 0x7F);
         if ((chData & 0x80) == 0) {
             return n;
         }
         if (n == std::numeric_limits<I>::max()) {
             throw std::ios_base::failure("ReadVarInt(): size too large");
         }
         n++;
     }
 }
 
 /**
  * Simple wrapper class to serialize objects using a formatter; used by
  * Using().
  */
 template <typename Formatter, typename T> class Wrapper {
     static_assert(std::is_lvalue_reference<T>::value,
                   "Wrapper needs an lvalue reference type T");
 
 protected:
     T m_object;
 
 public:
     explicit Wrapper(T obj) : m_object(obj) {}
     template <typename Stream> void Serialize(Stream &s) const {
         Formatter().Ser(s, m_object);
     }
     template <typename Stream> void Unserialize(Stream &s) {
         Formatter().Unser(s, m_object);
     }
 };
 
 /**
  * Cause serialization/deserialization of an object to be done using a
  * specified formatter class.
  *
  * To use this, you need a class Formatter that has public functions Ser(stream,
  * const object&) for serialization, and Unser(stream, object&) for
  * deserialization. Serialization routines (inside READWRITE, or directly with
  * << and >> operators), can then use Using<Formatter>(object).
  *
  * This works by constructing a Wrapper<Formatter, T>-wrapped version of object,
  * where T is const during serialization, and non-const during deserialization,
  * which maintains const correctness.
  */
 template <typename Formatter, typename T>
 static inline Wrapper<Formatter, T &> Using(T &&t) {
     return Wrapper<Formatter, T &>(t);
 }
 
 #define VARINT_MODE(obj, mode) Using<VarIntFormatter<mode>>(obj)
 #define VARINT(obj) Using<VarIntFormatter<VarIntMode::DEFAULT>>(obj)
 #define COMPACTSIZE(obj) Using<CompactSizeFormatter>(obj)
 #define LIMITED_STRING(obj, n) LimitedString<n>(REF(obj))
 
 /**
  * Serialization wrapper class for integers in VarInt format.
  */
 template <VarIntMode Mode> struct VarIntFormatter {
     template <typename Stream, typename I> void Ser(Stream &s, I v) {
         WriteVarInt<Stream, Mode, typename std::remove_cv<I>::type>(s, v);
     }
 
     template <typename Stream, typename I> void Unser(Stream &s, I &v) {
         v = ReadVarInt<Stream, Mode, typename std::remove_cv<I>::type>(s);
     }
 };
 
 /** Serialization wrapper class for big-endian integers.
  *
  * Use this wrapper around integer types that are stored in memory in native
  * byte order, but serialized in big endian notation. This is only intended
  * to implement serializers that are compatible with existing formats, and
  * its use is not recommended for new data structures.
  *
  * Only 16-bit types are supported for now.
  */
 template <typename I> class BigEndian {
 protected:
     I &m_val;
 
 public:
     explicit BigEndian(I &val) : m_val(val) {
         static_assert(std::is_unsigned<I>::value,
                       "BigEndian type must be unsigned integer");
         static_assert(sizeof(I) == 2 && std::numeric_limits<I>::min() == 0 &&
                           std::numeric_limits<I>::max() ==
                               std::numeric_limits<uint16_t>::max(),
                       "Unsupported BigEndian size");
     }
 
     template <typename Stream> void Serialize(Stream &s) const {
         ser_writedata16be(s, m_val);
     }
 
     template <typename Stream> void Unserialize(Stream &s) {
         m_val = ser_readdata16be(s);
     }
 };
 
 /** Formatter for integers in CompactSize format. */
 struct CompactSizeFormatter {
     template <typename Stream, typename I> void Unser(Stream &s, I &v) {
         uint64_t n = ReadCompactSize<Stream>(s);
         if (n < std::numeric_limits<I>::min() ||
             n > std::numeric_limits<I>::max()) {
             throw std::ios_base::failure("CompactSize exceeds limit of type");
         }
         v = n;
     }
 
     template <typename Stream, typename I> void Ser(Stream &s, I v) {
         static_assert(std::is_unsigned<I>::value,
                       "CompactSize only supported for unsigned integers");
         static_assert(std::numeric_limits<I>::max() <=
                           std::numeric_limits<uint64_t>::max(),
                       "CompactSize only supports 64-bit integers and below");
 
         WriteCompactSize<Stream>(s, v);
     }
 };
 
 template <size_t Limit> class LimitedString {
 protected:
     std::string &string;
 
 public:
     explicit LimitedString(std::string &_string) : string(_string) {}
 
     template <typename Stream> void Unserialize(Stream &s) {
         size_t size = ReadCompactSize(s);
         if (size > Limit) {
             throw std::ios_base::failure("String length limit exceeded");
         }
         string.resize(size);
         if (size != 0) {
             s.read((char *)string.data(), size);
         }
     }
 
     template <typename Stream> void Serialize(Stream &s) const {
         WriteCompactSize(s, string.size());
         if (!string.empty()) {
             s.write((char *)string.data(), string.size());
         }
     }
 };
 
 template <typename I> BigEndian<I> WrapBigEndian(I &n) {
     return BigEndian<I>(n);
 }
 
 /**
  * Formatter to serialize/deserialize vector elements using another formatter
  *
  * Example:
  *   struct X {
  *     std::vector<uint64_t> v;
  *     SERIALIZE_METHODS(X, obj) {
  *       READWRITE(Using<VectorFormatter<VarInt>>(obj.v));
  *     }
  *   };
  * will define a struct that contains a vector of uint64_t, which is serialized
  * as a vector of VarInt-encoded integers.
  *
  * V is not required to be an std::vector type. It works for any class that
- * exposes a value_type, size, reserve, push_back, and const iterators.
+ * exposes a value_type, size, reserve, emplace_back, back, and const iterators.
  */
 template <class Formatter> struct VectorFormatter {
     template <typename Stream, typename V> void Ser(Stream &s, const V &v) {
+        Formatter formatter;
         WriteCompactSize(s, v.size());
         for (const typename V::value_type &elem : v) {
-            s << Using<Formatter>(elem);
+            formatter.Ser(s, elem);
         }
     }
 
     template <typename Stream, typename V> void Unser(Stream &s, V &v) {
+        Formatter formatter;
         v.clear();
         size_t size = ReadCompactSize(s);
         size_t allocated = 0;
         while (allocated < size) {
             // For DoS prevention, do not blindly allocate as much as the stream
             // claims to contain. Instead, allocate in 5MiB batches, so that an
             // attacker actually needs to provide X MiB of data to make us
             // allocate X+5 Mib.
             static_assert(sizeof(typename V::value_type) <= MAX_VECTOR_ALLOCATE,
                           "Vector element size too large");
             allocated =
                 std::min(size, allocated + MAX_VECTOR_ALLOCATE /
                                                sizeof(typename V::value_type));
             v.reserve(allocated);
             while (v.size() < allocated) {
-                typename V::value_type val;
-                s >> Using<Formatter>(val);
-                v.push_back(std::move(val));
+                v.emplace_back();
+                formatter.Unser(s, v.back());
             }
         }
     };
 };
 
 /**
  * Forward declarations
  */
 
 /**
  * string
  */
 template <typename Stream, typename C>
 void Serialize(Stream &os, const std::basic_string<C> &str);
 template <typename Stream, typename C>
 void Unserialize(Stream &is, std::basic_string<C> &str);
 
 /**
  * prevector
  * prevectors of uint8_t are a special case and are intended to be serialized as
  * a single opaque blob.
  */
 template <typename Stream, unsigned int N, typename T>
 void Serialize_impl(Stream &os, const prevector<N, T> &v, const uint8_t &);
 template <typename Stream, unsigned int N, typename T, typename V>
 void Serialize_impl(Stream &os, const prevector<N, T> &v, const V &);
 template <typename Stream, unsigned int N, typename T>
 inline void Serialize(Stream &os, const prevector<N, T> &v);
 template <typename Stream, unsigned int N, typename T>
 void Unserialize_impl(Stream &is, prevector<N, T> &v, const uint8_t &);
 template <typename Stream, unsigned int N, typename T, typename V>
 void Unserialize_impl(Stream &is, prevector<N, T> &v, const V &);
 template <typename Stream, unsigned int N, typename T>
 inline void Unserialize(Stream &is, prevector<N, T> &v);
 
 /**
  * vector
  * vectors of uint8_t are a special case and are intended to be serialized as a
  * single opaque blob.
  */
 template <typename Stream, typename T, typename A>
 void Serialize_impl(Stream &os, const std::vector<T, A> &v, const uint8_t &);
 template <typename Stream, typename T, typename A>
 void Serialize_impl(Stream &os, const std::vector<T, A> &v, const bool &);
 template <typename Stream, typename T, typename A, typename V>
 void Serialize_impl(Stream &os, const std::vector<T, A> &v, const V &);
 template <typename Stream, typename T, typename A>
 inline void Serialize(Stream &os, const std::vector<T, A> &v);
 template <typename Stream, typename T, typename A>
 void Unserialize_impl(Stream &is, std::vector<T, A> &v, const uint8_t &);
 template <typename Stream, typename T, typename A, typename V>
 void Unserialize_impl(Stream &is, std::vector<T, A> &v, const V &);
 template <typename Stream, typename T, typename A>
 inline void Unserialize(Stream &is, std::vector<T, A> &v);
 
 /**
  * pair
  */
 template <typename Stream, typename K, typename T>
 void Serialize(Stream &os, const std::pair<K, T> &item);
 template <typename Stream, typename K, typename T>
 void Unserialize(Stream &is, std::pair<K, T> &item);
 
 /**
  * map
  */
 template <typename Stream, typename K, typename T, typename Pred, typename A>
 void Serialize(Stream &os, const std::map<K, T, Pred, A> &m);
 template <typename Stream, typename K, typename T, typename Pred, typename A>
 void Unserialize(Stream &is, std::map<K, T, Pred, A> &m);
 
 /**
  * set
  */
 template <typename Stream, typename K, typename Pred, typename A>
 void Serialize(Stream &os, const std::set<K, Pred, A> &m);
 template <typename Stream, typename K, typename Pred, typename A>
 void Unserialize(Stream &is, std::set<K, Pred, A> &m);
 
 /**
  * shared_ptr
  */
 template <typename Stream, typename T>
 void Serialize(Stream &os, const std::shared_ptr<const T> &p);
 template <typename Stream, typename T>
 void Unserialize(Stream &os, std::shared_ptr<const T> &p);
 
 /**
  * unique_ptr
  */
 template <typename Stream, typename T>
 void Serialize(Stream &os, const std::unique_ptr<const T> &p);
 template <typename Stream, typename T>
 void Unserialize(Stream &os, std::unique_ptr<const T> &p);
 
 /**
  * If none of the specialized versions above matched, default to calling member
  * function.
  */
 template <typename Stream, typename T>
 inline void Serialize(Stream &os, const T &a) {
     a.Serialize(os);
 }
 
 template <typename Stream, typename T>
 inline void Unserialize(Stream &is, T &&a) {
     a.Unserialize(is);
 }
 
 /**
  * Default formatter. Serializes objects as themselves.
  *
  * The vector/prevector serialization code passes this to VectorFormatter
  * to enable reusing that logic. It shouldn't be needed elsewhere.
  */
 struct DefaultFormatter {
     template <typename Stream, typename T>
     static void Ser(Stream &s, const T &t) {
         Serialize(s, t);
     }
 
     template <typename Stream, typename T> static void Unser(Stream &s, T &t) {
         Unserialize(s, t);
     }
 };
 
 /**
  * string
  */
 template <typename Stream, typename C>
 void Serialize(Stream &os, const std::basic_string<C> &str) {
     WriteCompactSize(os, str.size());
     if (!str.empty()) {
         os.write((char *)str.data(), str.size() * sizeof(C));
     }
 }
 
 template <typename Stream, typename C>
 void Unserialize(Stream &is, std::basic_string<C> &str) {
     size_t nSize = ReadCompactSize(is);
     str.resize(nSize);
     if (nSize != 0) {
         is.read((char *)str.data(), nSize * sizeof(C));
     }
 }
 
 /**
  * prevector
  */
 template <typename Stream, unsigned int N, typename T>
 void Serialize_impl(Stream &os, const prevector<N, T> &v, const uint8_t &) {
     WriteCompactSize(os, v.size());
     if (!v.empty()) {
         os.write((char *)v.data(), v.size() * sizeof(T));
     }
 }
 
 template <typename Stream, unsigned int N, typename T, typename V>
 void Serialize_impl(Stream &os, const prevector<N, T> &v, const V &) {
     Serialize(os, Using<VectorFormatter<DefaultFormatter>>(v));
 }
 
 template <typename Stream, unsigned int N, typename T>
 inline void Serialize(Stream &os, const prevector<N, T> &v) {
     Serialize_impl(os, v, T());
 }
 
 template <typename Stream, unsigned int N, typename T>
 void Unserialize_impl(Stream &is, prevector<N, T> &v, const uint8_t &) {
     // Limit size per read so bogus size value won't cause out of memory
     v.clear();
     size_t nSize = ReadCompactSize(is);
     size_t i = 0;
     while (i < nSize) {
         size_t blk = std::min(nSize - i, size_t(1 + 4999999 / sizeof(T)));
         v.resize_uninitialized(i + blk);
         is.read((char *)&v[i], blk * sizeof(T));
         i += blk;
     }
 }
 
 template <typename Stream, unsigned int N, typename T, typename V>
 void Unserialize_impl(Stream &is, prevector<N, T> &v, const V &) {
     Unserialize(is, Using<VectorFormatter<DefaultFormatter>>(v));
 }
 
 template <typename Stream, unsigned int N, typename T>
 inline void Unserialize(Stream &is, prevector<N, T> &v) {
     Unserialize_impl(is, v, T());
 }
 
 /**
  * vector
  */
 template <typename Stream, typename T, typename A>
 void Serialize_impl(Stream &os, const std::vector<T, A> &v, const uint8_t &) {
     WriteCompactSize(os, v.size());
     if (!v.empty()) {
         os.write((char *)v.data(), v.size() * sizeof(T));
     }
 }
 
 template <typename Stream, typename T, typename A>
 void Serialize_impl(Stream &os, const std::vector<T, A> &v, const bool &) {
     // A special case for std::vector<bool>, as dereferencing
     // std::vector<bool>::const_iterator does not result in a const bool&
     // due to std::vector's special casing for bool arguments.
     WriteCompactSize(os, v.size());
     for (bool elem : v) {
         ::Serialize(os, elem);
     }
 }
 
 template <typename Stream, typename T, typename A, typename V>
 void Serialize_impl(Stream &os, const std::vector<T, A> &v, const V &) {
     Serialize(os, Using<VectorFormatter<DefaultFormatter>>(v));
 }
 
 template <typename Stream, typename T, typename A>
 inline void Serialize(Stream &os, const std::vector<T, A> &v) {
     Serialize_impl(os, v, T());
 }
 
 template <typename Stream, typename T, typename A>
 void Unserialize_impl(Stream &is, std::vector<T, A> &v, const uint8_t &) {
     // Limit size per read so bogus size value won't cause out of memory
     v.clear();
     size_t nSize = ReadCompactSize(is);
     size_t i = 0;
     while (i < nSize) {
         size_t blk = std::min(nSize - i, size_t(1 + 4999999 / sizeof(T)));
         v.resize(i + blk);
         is.read((char *)&v[i], blk * sizeof(T));
         i += blk;
     }
 }
 
 template <typename Stream, typename T, typename A, typename V>
 void Unserialize_impl(Stream &is, std::vector<T, A> &v, const V &) {
     Unserialize(is, Using<VectorFormatter<DefaultFormatter>>(v));
 }
 
 template <typename Stream, typename T, typename A>
 inline void Unserialize(Stream &is, std::vector<T, A> &v) {
     Unserialize_impl(is, v, T());
 }
 
 /**
  * pair
  */
 template <typename Stream, typename K, typename T>
 void Serialize(Stream &os, const std::pair<K, T> &item) {
     Serialize(os, item.first);
     Serialize(os, item.second);
 }
 
 template <typename Stream, typename K, typename T>
 void Unserialize(Stream &is, std::pair<K, T> &item) {
     Unserialize(is, item.first);
     Unserialize(is, item.second);
 }
 
 /**
  * map
  */
 template <typename Stream, typename K, typename T, typename Pred, typename A>
 void Serialize(Stream &os, const std::map<K, T, Pred, A> &m) {
     WriteCompactSize(os, m.size());
     for (const auto &entry : m) {
         Serialize(os, entry);
     }
 }
 
 template <typename Stream, typename K, typename T, typename Pred, typename A>
 void Unserialize(Stream &is, std::map<K, T, Pred, A> &m) {
     m.clear();
     size_t nSize = ReadCompactSize(is);
     typename std::map<K, T, Pred, A>::iterator mi = m.begin();
     for (size_t i = 0; i < nSize; i++) {
         std::pair<K, T> item;
         Unserialize(is, item);
         mi = m.insert(mi, item);
     }
 }
 
 /**
  * set
  */
 template <typename Stream, typename K, typename Pred, typename A>
 void Serialize(Stream &os, const std::set<K, Pred, A> &m) {
     WriteCompactSize(os, m.size());
     for (const K &i : m) {
         Serialize(os, i);
     }
 }
 
 template <typename Stream, typename K, typename Pred, typename A>
 void Unserialize(Stream &is, std::set<K, Pred, A> &m) {
     m.clear();
     size_t nSize = ReadCompactSize(is);
     typename std::set<K, Pred, A>::iterator it = m.begin();
     for (size_t i = 0; i < nSize; i++) {
         K key;
         Unserialize(is, key);
         it = m.insert(it, key);
     }
 }
 
 /**
  * unique_ptr
  */
 template <typename Stream, typename T>
 void Serialize(Stream &os, const std::unique_ptr<const T> &p) {
     Serialize(os, *p);
 }
 
 template <typename Stream, typename T>
 void Unserialize(Stream &is, std::unique_ptr<const T> &p) {
     p.reset(new T(deserialize, is));
 }
 
 /**
  * shared_ptr
  */
 template <typename Stream, typename T>
 void Serialize(Stream &os, const std::shared_ptr<const T> &p) {
     Serialize(os, *p);
 }
 
 template <typename Stream, typename T>
 void Unserialize(Stream &is, std::shared_ptr<const T> &p) {
     p = std::make_shared<const T>(deserialize, is);
 }
 
 /**
  * Support for ADD_SERIALIZE_METHODS and READWRITE macro
  */
 struct CSerActionSerialize {
     constexpr bool ForRead() const { return false; }
 };
 struct CSerActionUnserialize {
     constexpr bool ForRead() const { return true; }
 };
 
 /**
  * ::GetSerializeSize implementations
  *
  * Computing the serialized size of objects is done through a special stream
  * object of type CSizeComputer, which only records the number of bytes written
  * to it.
  *
  * If your Serialize or SerializationOp method has non-trivial overhead for
  * serialization, it may be worthwhile to implement a specialized version for
  * CSizeComputer, which uses the s.seek() method to record bytes that would
  * be written instead.
  */
 class CSizeComputer {
 protected:
     size_t nSize;
 
     const int nVersion;
 
 public:
     explicit CSizeComputer(int nVersionIn) : nSize(0), nVersion(nVersionIn) {}
 
     void write(const char *psz, size_t _nSize) { this->nSize += _nSize; }
 
     /** Pretend _nSize bytes are written, without specifying them. */
     void seek(size_t _nSize) { this->nSize += _nSize; }
 
     template <typename T> CSizeComputer &operator<<(const T &obj) {
         ::Serialize(*this, obj);
         return (*this);
     }
 
     size_t size() const { return nSize; }
 
     int GetVersion() const { return nVersion; }
 };
 
 template <typename Stream> void SerializeMany(Stream &s) {}
 
 template <typename Stream, typename Arg, typename... Args>
 void SerializeMany(Stream &s, const Arg &arg, const Args &... args) {
     ::Serialize(s, arg);
     ::SerializeMany(s, args...);
 }
 
 template <typename Stream> inline void UnserializeMany(Stream &s) {}
 
 template <typename Stream, typename Arg, typename... Args>
 inline void UnserializeMany(Stream &s, Arg &&arg, Args &&... args) {
     ::Unserialize(s, arg);
     ::UnserializeMany(s, args...);
 }
 
 template <typename Stream, typename... Args>
 inline void SerReadWriteMany(Stream &s, CSerActionSerialize ser_action,
                              const Args &... args) {
     ::SerializeMany(s, args...);
 }
 
 template <typename Stream, typename... Args>
 inline void SerReadWriteMany(Stream &s, CSerActionUnserialize ser_action,
                              Args &&... args) {
     ::UnserializeMany(s, args...);
 }
 
 template <typename I> inline void WriteVarInt(CSizeComputer &s, I n) {
     s.seek(GetSizeOfVarInt<I>(n));
 }
 
 inline void WriteCompactSize(CSizeComputer &s, uint64_t nSize) {
     s.seek(GetSizeOfCompactSize(nSize));
 }
 
 template <typename T> size_t GetSerializeSize(const T &t, int nVersion = 0) {
     return (CSizeComputer(nVersion) << t).size();
 }
 
 template <typename... T>
 size_t GetSerializeSizeMany(int nVersion, const T &... t) {
     CSizeComputer sc(nVersion);
     SerializeMany(sc, t...);
     return sc.size();
 }
 
 #endif // BITCOIN_SERIALIZE_H