9 files changed, 529 insertions, 161 deletions

diff --git a/src/corelib/tools/qarraydataops.h b/src/corelib/tools/qarraydataops.h
index 0d2be5d51c..1d74f49993 100644
--- a/src/corelib/tools/qarraydataops.h
+++ b/src/corelib/tools/qarraydataops.h
@@ -117,6 +117,9 @@ struct QPodArrayOps
         this->size += int(n);
     }
 
+    template <typename ...Args>
+    void emplaceBack(Args&&... args) { this->emplace(this->end(), T(std::forward<Args>(args)...)); }
+
     void truncate(size_t newSize)
     {
         Q_ASSERT(this->isMutable());
@@ -163,16 +166,28 @@ struct QPodArrayOps
             *where++ = t;
     }
 
-    void insert(T *where, T &&t)
+    template <typename ...Args>
+    void createInPlace(T *where, Args&&... args) { new (where) T(std::forward<Args>(args)...); }
+
+    template <typename ...Args>
+    void emplace(T *where, Args&&... args)
     {
         Q_ASSERT(!this->isShared());
         Q_ASSERT(where >= this->begin() && where <= this->end());
         Q_ASSERT(this->allocatedCapacity() - this->size >= 1);
 
-        ::memmove(static_cast<void *>(where + 1), static_cast<void *>(where),
-                  (static_cast<const T*>(this->end()) - where) * sizeof(T));
-        this->size += 1;
-        new (where) T(std::move(t));
+        if (where == this->end()) {
+            new (this->end()) T(std::forward<Args>(args)...);
+        } else {
+            // Preserve the value, because it might be a reference to some part of the moved chunk
+            T t(std::forward<Args>(args)...);
+
+            ::memmove(static_cast<void *>(where + 1), static_cast<void *>(where),
+                      (static_cast<const T*>(this->end()) - where) * sizeof(T));
+            *where = t;
+        }
+
+        ++this->size;
     }
 
 
@@ -289,6 +304,12 @@ struct QGenericArrayOps
         }
     }
 
+    template <typename ...Args>
+    void emplaceBack(Args&&... args)
+    {
+        this->emplace(this->end(), std::forward<Args>(args)...);
+    }
+
     void truncate(size_t newSize)
     {
         Q_ASSERT(this->isMutable());
@@ -444,31 +465,20 @@ struct QGenericArrayOps
         }
     }
 
-    void insert(T *where, T &&t)
+    template <typename ...Args>
+    void createInPlace(T *where, Args&&... args) { new (where) T(std::forward<Args>(args)...); }
+
+    template <typename iterator, typename ...Args>
+    void emplace(iterator where, Args&&... args)
     {
         Q_ASSERT(!this->isShared());
         Q_ASSERT(where >= this->begin() && where <= this->end());
         Q_ASSERT(this->allocatedCapacity() - this->size >= 1);
 
-        // Array may be truncated at where in case of exceptions
-        T *const end = this->end();
-
-        if (where != end) {
-            // Move elements in array
-            T *readIter = end - 1;
-            T *writeIter = end;
-            new (writeIter) T(std::move(*readIter));
-            while (readIter > where) {
-                --readIter;
-                --writeIter;
-                *writeIter = std::move(*readIter);
-            }
-            *where = std::move(t);
-        } else {
-            new (where) T(std::move(t));
-        }
-
+        createInPlace(this->end(), std::forward<Args>(args)...);
         ++this->size;
+
+        std::rotate(where, this->end() - 1, this->end());
     }
 
     void erase(T *b, T *e)
diff --git a/src/corelib/tools/qcontiguouscache.h b/src/corelib/tools/qcontiguouscache.h
index 8cae7d1651..451ba3e8de 100644
--- a/src/corelib/tools/qcontiguouscache.h
+++ b/src/corelib/tools/qcontiguouscache.h
@@ -56,8 +56,6 @@ struct Q_CORE_EXPORT QContiguousCacheData
     int count;
     int start;
     int offset;
-    uint sharable : 1;
-    uint reserved : 31;
 
     // total is 24 bytes (HP-UX aCC: 40 bytes)
     // the next entry is already aligned to 8 bytes
@@ -96,7 +94,7 @@ public:
     typedef int size_type;
 
     explicit QContiguousCache(int capacity = 0);
-    QContiguousCache(const QContiguousCache<T> &v) : d(v.d) { d->ref.ref(); if (!d->sharable) detach_helper(); }
+    QContiguousCache(const QContiguousCache<T> &v) : d(v.d) { d->ref.ref(); }
 
     inline ~QContiguousCache() { if (!d) return; if (!d->ref.deref()) freeData(p); }
 
@@ -178,8 +176,6 @@ void QContiguousCache<T>::detach_helper()
     x.d->start = d->start;
     x.d->offset = d->offset;
     x.d->alloc = d->alloc;
-    x.d->sharable = true;
-    x.d->reserved = 0;
 
     T *dest = x.p->array + x.d->start;
     T *src = p->array + d->start;
@@ -267,7 +263,6 @@ void QContiguousCache<T>::clear()
         x.d->ref.storeRelaxed(1);
         x.d->alloc = d->alloc;
         x.d->count = x.d->start = x.d->offset = 0;
-        x.d->sharable = true;
         if (!d->ref.deref()) freeData(p);
         d = x.d;
     }
@@ -287,7 +282,6 @@ QContiguousCache<T>::QContiguousCache(int cap)
     d->ref.storeRelaxed(1);
     d->alloc = cap;
     d->count = d->start = d->offset = 0;
-    d->sharable = true;
 }
 
 template <typename T>
@@ -297,8 +291,6 @@ QContiguousCache<T> &QContiguousCache<T>::operator=(const QContiguousCache<T> &o
     if (!d->ref.deref())
         freeData(p);
     d = other.d;
-    if (!d->sharable)
-        detach_helper();
     return *this;
 }
 
diff --git a/src/corelib/tools/qcryptographichash.cpp b/src/corelib/tools/qcryptographichash.cpp
index fa8d21e07a..1d4afabedd 100644
--- a/src/corelib/tools/qcryptographichash.cpp
+++ b/src/corelib/tools/qcryptographichash.cpp
@@ -359,53 +359,67 @@ void QCryptographicHash::reset()
     Adds the first \a length chars of \a data to the cryptographic
     hash.
 */
-void QCryptographicHash::addData(const char *data, int length)
+void QCryptographicHash::addData(const char *data, qsizetype length)
 {
-    switch (d->method) {
-    case Sha1:
-        sha1Update(&d->sha1Context, (const unsigned char *)data, length);
-        break;
+    Q_ASSERT(length >= 0);
+
+#if QT_POINTER_SIZE == 8
+    // feed the data UINT_MAX bytes at a time, as some of the methods below
+    // take a uint (of course, feeding more than 4G of data into the hashing
+    // functions will be pretty slow anyway)
+    qsizetype remaining = length;
+    while (remaining) {
+        length = qMin(qsizetype(std::numeric_limits<uint>::max()), remaining);
+        remaining -= length;
+#else
+    {
+#endif
+        switch (d->method) {
+        case Sha1:
+            sha1Update(&d->sha1Context, (const unsigned char *)data, length);
+            break;
 #ifdef QT_CRYPTOGRAPHICHASH_ONLY_SHA1
-    default:
-        Q_ASSERT_X(false, "QCryptographicHash", "Method not compiled in");
-        Q_UNREACHABLE();
-        break;
+        default:
+            Q_ASSERT_X(false, "QCryptographicHash", "Method not compiled in");
+            Q_UNREACHABLE();
+            break;
 #else
-    case Md4:
-        md4_update(&d->md4Context, (const unsigned char *)data, length);
-        break;
-    case Md5:
-        MD5Update(&d->md5Context, (const unsigned char *)data, length);
-        break;
-    case Sha224:
-        SHA224Input(&d->sha224Context, reinterpret_cast<const unsigned char *>(data), length);
-        break;
-    case Sha256:
-        SHA256Input(&d->sha256Context, reinterpret_cast<const unsigned char *>(data), length);
-        break;
-    case Sha384:
-        SHA384Input(&d->sha384Context, reinterpret_cast<const unsigned char *>(data), length);
-        break;
-    case Sha512:
-        SHA512Input(&d->sha512Context, reinterpret_cast<const unsigned char *>(data), length);
-        break;
-    case RealSha3_224:
-    case Keccak_224:
-        sha3Update(&d->sha3Context, reinterpret_cast<const BitSequence *>(data), quint64(length) * 8);
-        break;
-    case RealSha3_256:
-    case Keccak_256:
-        sha3Update(&d->sha3Context, reinterpret_cast<const BitSequence *>(data), quint64(length) * 8);
-        break;
-    case RealSha3_384:
-    case Keccak_384:
-        sha3Update(&d->sha3Context, reinterpret_cast<const BitSequence *>(data), quint64(length) * 8);
-        break;
-    case RealSha3_512:
-    case Keccak_512:
-        sha3Update(&d->sha3Context, reinterpret_cast<const BitSequence *>(data), quint64(length) * 8);
-        break;
+        case Md4:
+            md4_update(&d->md4Context, (const unsigned char *)data, length);
+            break;
+        case Md5:
+            MD5Update(&d->md5Context, (const unsigned char *)data, length);
+            break;
+        case Sha224:
+            SHA224Input(&d->sha224Context, reinterpret_cast<const unsigned char *>(data), length);
+            break;
+        case Sha256:
+            SHA256Input(&d->sha256Context, reinterpret_cast<const unsigned char *>(data), length);
+            break;
+        case Sha384:
+            SHA384Input(&d->sha384Context, reinterpret_cast<const unsigned char *>(data), length);
+            break;
+        case Sha512:
+            SHA512Input(&d->sha512Context, reinterpret_cast<const unsigned char *>(data), length);
+            break;
+        case RealSha3_224:
+        case Keccak_224:
+            sha3Update(&d->sha3Context, reinterpret_cast<const BitSequence *>(data), quint64(length) * 8);
+            break;
+        case RealSha3_256:
+        case Keccak_256:
+            sha3Update(&d->sha3Context, reinterpret_cast<const BitSequence *>(data), quint64(length) * 8);
+            break;
+        case RealSha3_384:
+        case Keccak_384:
+            sha3Update(&d->sha3Context, reinterpret_cast<const BitSequence *>(data), quint64(length) * 8);
+            break;
+        case RealSha3_512:
+        case Keccak_512:
+            sha3Update(&d->sha3Context, reinterpret_cast<const BitSequence *>(data), quint64(length) * 8);
+            break;
 #endif
+        }
     }
     d->result.clear();
 }
diff --git a/src/corelib/tools/qcryptographichash.h b/src/corelib/tools/qcryptographichash.h
index ad1de7c756..f76fe2d013 100644
--- a/src/corelib/tools/qcryptographichash.h
+++ b/src/corelib/tools/qcryptographichash.h
@@ -94,7 +94,7 @@ public:
 
     void reset();
 
-    void addData(const char *data, int length);
+    void addData(const char *data, qsizetype length);
     void addData(const QByteArray &data);
     bool addData(QIODevice* device);
 
diff --git a/src/corelib/tools/qset.h b/src/corelib/tools/qset.h
index f98bb051ec..ef363ed52d 100644
--- a/src/corelib/tools/qset.h
+++ b/src/corelib/tools/qset.h
@@ -105,11 +105,7 @@ public:
         friend class QSet<T>;
 
     public:
-#if QT_DEPRECATED_SINCE(5, 15)
-        typedef std::bidirectional_iterator_tag iterator_category;
-#else
         typedef std::forward_iterator_tag iterator_category;
-#endif
         typedef qptrdiff difference_type;
         typedef T value_type;
         typedef const T *pointer;
@@ -129,15 +125,6 @@ public:
             { return i != o.i; }
         inline iterator &operator++() { ++i; return *this; }
         inline iterator operator++(int) { iterator r = *this; ++i; return r; }
-#if QT_DEPRECATED_SINCE(5, 15)
-        inline QT_DEPRECATED iterator &operator--() { --i; return *this; }
-        inline QT_DEPRECATED iterator operator--(int) { iterator r = *this; --i; return r; }
-        inline QT_DEPRECATED iterator operator+(int j) const { return i + j; }
-        inline QT_DEPRECATED iterator operator-(int j) const { return i - j; }
-        friend inline QT_DEPRECATED iterator operator+(int j, iterator k) { return k + j; }
-        inline QT_DEPRECATED iterator &operator+=(int j) { i += j; return *this; }
-        inline QT_DEPRECATED iterator &operator-=(int j) { i -= j; return *this; }
-#endif
     };
 
     class const_iterator
@@ -148,11 +135,7 @@ public:
         friend class QSet<T>;
 
     public:
-#if QT_DEPRECATED_SINCE(5, 15)
-        typedef std::bidirectional_iterator_tag iterator_category;
-#else
         typedef std::forward_iterator_tag iterator_category;
-#endif
         typedef qptrdiff difference_type;
         typedef T value_type;
         typedef const T *pointer;
@@ -170,15 +153,6 @@ public:
         inline bool operator!=(const const_iterator &o) const { return i != o.i; }
         inline const_iterator &operator++() { ++i; return *this; }
         inline const_iterator operator++(int) { const_iterator r = *this; ++i; return r; }
-#if QT_DEPRECATED_SINCE(5, 15)
-        inline QT_DEPRECATED const_iterator &operator--() { --i; return *this; }
-        inline QT_DEPRECATED const_iterator operator--(int) { const_iterator r = *this; --i; return r; }
-        inline QT_DEPRECATED const_iterator operator+(int j) const { return i + j; }
-        inline QT_DEPRECATED const_iterator operator-(int j) const { return i - j; }
-        friend inline QT_DEPRECATED const_iterator operator+(int j, const_iterator k) { return k + j; }
-        inline QT_DEPRECATED const_iterator &operator+=(int j) { i += j; return *this; }
-        inline QT_DEPRECATED const_iterator &operator-=(int j) { i -= j; return *this; }
-#endif
     };
 
     // STL style
@@ -191,23 +165,10 @@ public:
     inline const_iterator cend() const noexcept { return q_hash.end(); }
     inline const_iterator constEnd() const noexcept { return q_hash.constEnd(); }
 
-#if QT_DEPRECATED_SINCE(5, 15)
-    typedef std::reverse_iterator<iterator> reverse_iterator;
-    typedef std::reverse_iterator<const_iterator> const_reverse_iterator;
-
-    reverse_iterator QT_DEPRECATED rbegin() { return reverse_iterator(end()); }
-    reverse_iterator QT_DEPRECATED rend() { return reverse_iterator(begin()); }
-    const_reverse_iterator QT_DEPRECATED rbegin() const noexcept { return const_reverse_iterator(end()); }
-    const_reverse_iterator QT_DEPRECATED rend() const noexcept { return const_reverse_iterator(begin()); }
-    const_reverse_iterator QT_DEPRECATED crbegin() const noexcept { return const_reverse_iterator(end()); }
-    const_reverse_iterator QT_DEPRECATED crend() const noexcept { return const_reverse_iterator(begin()); }
-#endif
-
     iterator erase(iterator i)
     { return erase(m2c(i)); }
     iterator erase(const_iterator i)
     {
-        Q_ASSERT_X(isValidIterator(i), "QSet::erase", "The specified const_iterator argument 'i' is invalid");
         return q_hash.erase(reinterpret_cast<typename Hash::const_iterator &>(i));
     }
 
@@ -263,15 +224,6 @@ private:
 
     static const_iterator m2c(iterator it) noexcept
     { return const_iterator(typename Hash::const_iterator(it.i.i)); }
-
-    bool isValidIterator(const iterator &i) const
-    {
-        return q_hash.isValidIterator(reinterpret_cast<const typename Hash::iterator&>(i));
-    }
-    bool isValidIterator(const const_iterator &i) const noexcept
-    {
-        return q_hash.isValidIterator(reinterpret_cast<const typename Hash::const_iterator&>(i));
-    }
 };
 
 #if defined(__cpp_deduction_guides) && __cpp_deduction_guides >= 201606
@@ -415,14 +367,6 @@ public:
     inline const T &value() const { Q_ASSERT(item_exists()); return *n; }
     inline bool findNext(const T &t)
     { while (c->constEnd() != (n = i)) if (*i++ == t) return true; return false; }
-#if QT_DEPRECATED_SINCE(5, 15)
-    inline QT_DEPRECATED bool hasPrevious() const { return c->constBegin() != i; }
-    inline QT_DEPRECATED const T &previous() { n = --i; return *n; }
-    inline QT_DEPRECATED const T &peekPrevious() const { iterator p = i; return *--p; }
-    inline QT_DEPRECATED bool findPrevious(const T &t)
-    { while (c->constBegin() != i) if (*(n = --i) == t) return true;
-      n = c->end(); return false;  }
-#endif
 };
 #endif // QT_NO_JAVA_STYLE_ITERATORS
 
diff --git a/src/corelib/tools/qvector.h b/src/corelib/tools/qvector.h
index 3e98de41f4..2cfcb2e5dc 100644
--- a/src/corelib/tools/qvector.h
+++ b/src/corelib/tools/qvector.h
@@ -242,10 +242,14 @@ public:
     void append(const_reference t)
     { append(const_iterator(std::addressof(t)), const_iterator(std::addressof(t)) + 1); }
     void append(const_iterator i1, const_iterator i2);
-    void append(value_type &&t);
+    void append(rvalue_ref t) { emplaceBack(std::move(t)); }
     void append(const QVector<T> &l) { append(l.constBegin(), l.constEnd()); }
     void prepend(rvalue_ref t);
     void prepend(const T &t);
+
+    template <typename ...Args>
+    reference emplaceBack(Args&&... args) { return *emplace(count(), std::forward<Args>(args)...); }
+
     iterator insert(int i, parameter_type t)
     { return insert(i, 1, t); }
     iterator insert(int i, int n, parameter_type t);
@@ -264,7 +268,17 @@ public:
         Q_ASSERT_X(isValidIterator(before),  "QVector::insert", "The specified iterator argument 'before' is invalid");
         return insert(std::distance(constBegin(), before), std::move(t));
     }
-    iterator insert(int i, rvalue_ref t);
+    iterator insert(int i, rvalue_ref t) { return emplace(i, std::move(t)); }
+
+    template <typename ...Args>
+    iterator emplace(const_iterator before, Args&&... args)
+    {
+        Q_ASSERT_X(isValidIterator(before),  "QVector::emplace", "The specified iterator argument 'before' is invalid");
+        return emplace(std::distance(constBegin(), before), std::forward<Args>(args)...);
+    }
+
+    template <typename ...Args>
+    iterator emplace(int i, Args&&... args);
 #if 0
     template< class InputIt >
     iterator insert( const_iterator pos, InputIt first, InputIt last );
@@ -388,6 +402,10 @@ public:
     inline void push_front(const T &t) { prepend(t); }
     void pop_back() { removeLast(); }
     void pop_front() { removeFirst(); }
+
+    template <typename ...Args>
+    reference emplace_back(Args&&... args) { return emplaceBack(std::forward<Args>(args)...); }
+
     inline bool empty() const
     { return d->size == 0; }
     inline reference front() { return first(); }
@@ -538,27 +556,6 @@ inline void QVector<T>::append(const_iterator i1, const_iterator i2)
 }
 
 template <typename T>
-inline void QVector<T>::append(value_type &&t)
-{
-    const size_t newSize = size() + 1;
-    const bool isTooSmall = newSize > d->allocatedCapacity();
-    const bool isOverlapping = std::addressof(*d->begin()) <= std::addressof(t)
-            && std::addressof(t) < std::addressof(*d->end());
-    if (isTooSmall || d->needsDetach() || Q_UNLIKELY(isOverlapping)) {
-        typename Data::ArrayOptions flags = d->detachFlags();
-        if (isTooSmall)
-            flags |= Data::GrowsForward;
-        DataPointer detached(Data::allocate(d->detachCapacity(newSize), flags));
-        detached->copyAppend(constBegin(), constEnd());
-        detached->moveAppend(std::addressof(t), std::addressof(t) + 1);
-        d.swap(detached);
-    } else {
-        // we're detached and we can just move data around
-        d->moveAppend(std::addressof(t), std::addressof(t) + 1);
-    }
-}
-
-template <typename T>
 inline typename QVector<T>::iterator
 QVector<T>::insert(int i, int n, parameter_type t)
 {
@@ -592,10 +589,11 @@ QVector<T>::insert(int i, int n, parameter_type t)
 }
 
 template <typename T>
+template <typename ...Args>
 typename QVector<T>::iterator
-QVector<T>::insert(int i, rvalue_ref t)
+QVector<T>::emplace(int i, Args&&... args)
 {
-    Q_ASSERT_X(size_t(i) <= size_t(d->size), "QVector<T>::insert", "index out of range");
+     Q_ASSERT_X(i >= 0 && i <= d->size, "QVector<T>::insert", "index out of range");
 
     const size_t newSize = size() + 1;
     if (d->needsDetach() || newSize > d->allocatedCapacity()) {
@@ -605,12 +603,24 @@ QVector<T>::insert(int i, rvalue_ref t)
 
         DataPointer detached(Data::allocate(d->detachCapacity(newSize), flags));
         const_iterator where = constBegin() + i;
+
+        // First, create an element to handle cases, when a user moves
+        // the element from a container to the same container
+        detached->createInPlace(detached.begin() + i, std::forward<Args>(args)...);
+
+        // Then, put the first part of the elements to the new location
         detached->copyAppend(constBegin(), where);
-        detached->moveAppend(std::addressof(t), std::addressof(t) + 1);
+
+        // After that, increase the actual size, because we created
+        // one extra element
+        ++detached.size;
+
+        // Finally, put the rest of the elements to the new location
         detached->copyAppend(where, constEnd());
+
         d.swap(detached);
     } else {
-        d->insert(d.begin() + i, std::move(t));
+        d->emplace(d.begin() + i, std::forward<Args>(args)...);
     }
     return d.begin() + i;
 }
diff --git a/src/corelib/tools/qvector.qdoc b/src/corelib/tools/qvector.qdoc
index 116d962411..a5ea4073f8 100644
--- a/src/corelib/tools/qvector.qdoc
+++ b/src/corelib/tools/qvector.qdoc
@@ -646,6 +646,28 @@
     \sa append(), insert()
 */
 
+/*!
+    \fn template <typename T> template <typename ...Args> T &QVector<T>::emplaceBack(Args&&... args)
+    \fn template <typename T> template <typename ...Args> T &QVector<T>::emplace_back(Args&&... args)
+
+    Adds a new element to the end for the container. This new element
+    is constructed in-place using \a args as the arguments for its
+    construction.
+
+    Returns a reference to the new element.
+
+    Example:
+    \snippet code/src_corelib_tools_qvector.cpp emplace-back
+
+    It is also possible to access a newly created object by using
+    returned reference:
+    \snippet code/src_corelib_tools_qvector.cpp emplace-back-ref
+
+    This is the same as vector.emplace(vector.size(), \a args).
+
+    \sa emplace
+*/
+
 /*! \fn template <typename T> void QVector<T>::insert(int i, const T &value)
     \fn template <typename T> void QVector<T>::insert(int i, T &&value)
 
@@ -693,6 +715,26 @@
     first of the inserted items.
 */
 
+/*!
+    \fn template <typename T> template <typename ...Args> QVector<T>::iterator QVector<T>::emplace(int i, Args&&... args)
+
+    Extends the container by inserting a new element at position \a i.
+    This new element is constructed in-place using \a args as the
+    arguments for its construction.
+
+    Returns an iterator to the new element.
+
+    Example:
+    \snippet code/src_corelib_tools_qvector.cpp emplace
+
+    \note It is garanteed that the element will be created in place
+          at the beginning, but after that it might be copied or
+          moved to the right position.
+
+    \sa emplaceBack
+*/
+
+
 /*! \fn template <typename T> void QVector<T>::replace(int i, const T &value)
 
     Replaces the item at index position \a i with \a value.
@@ -838,6 +880,17 @@
     \sa takeFirst(), removeLast()
 */
 
+/*!
+    \fn template <typename T> template <typename ...Args> QVector<T>::iterator QVector<T>::emplace(QVector<T>::iterator before, Args&&... args)
+
+    \overload
+
+    Creates a new element in front of the item pointed to by the
+    iterator \a before. This new element is constructed in-place
+    using \a args as the arguments for its construction.
+
+    Returns an iterator to the new element.
+*/
 
 /*! \fn template <typename T> QVector<T> &QVector<T>::fill(const T &value, int size = -1)
 
diff --git a/src/corelib/tools/qversionnumber.cpp b/src/corelib/tools/qversionnumber.cpp
index 58e3c15560..0883896751 100644
--- a/src/corelib/tools/qversionnumber.cpp
+++ b/src/corelib/tools/qversionnumber.cpp
@@ -556,5 +556,199 @@ uint qHash(const QVersionNumber &key, uint seed)
     return seed;
 }
 
-QT_END_NAMESPACE
+/*!
+    \class QTypeRevision
+    \inmodule QtCore
+    \since 6.0
+    \brief The QTypeRevision class contains a lightweight representation of
+           a version number with two 8-bit segments, major and minor, either
+           of which can be unknown.
+
+    Use this class to describe revisions of a type. Compatible revisions can be
+    expressed as increments of the minor version. Breaking changes can be
+    expressed as increments of the major version. The return values of
+    \l QMetaMethod::revision() and \l QMetaProperty::revision() can be passed to
+    \l QTypeRevision::fromEncodedVersion(). The resulting major and minor versions
+    specify in which Qt versions the properties and methods were added.
+
+    \sa QMetaMethod::revision(), QMetaProperty::revision()
+*/
+
+/*!
+    \fn template<typename Integer> static bool QTypeRevision::isValidSegment(Integer segment)
+
+    Returns true if the given number can be used as either major or minor
+    version in a QTypeRevision. Valid segments need to be \c {>= 0} and \c {< 255}.
+*/
+
+/*!
+    \fn QTypeRevision::QTypeRevision()
+
+    Produces an invalid revision.
+
+    \sa isValid()
+*/
+
+/*!
+    \fn template <typename Major, typename Minor> static QTypeRevision QTypeRevision::fromVersion(Major majorVersion, Minor minorVersion)
+
+    Produces a QTypeRevision from the given \a majorVersion and \a minorVersion,
+    both of which need to be a valid segments.
+
+    \sa isValidSegment()
+*/
+
+/*!
+    \fn template <typename Major> static QTypeRevision QTypeRevision::fromMajorVersion(Major majorVersion)
+
+    Produces a QTypeRevision from the given \a majorVersion with an invalid minor
+    version. \a majorVersion needs to be a valid segment.
+
+    \sa isValidSegment()
+*/
+
+/*!
+    \fn template <typename Minor> static QTypeRevision QTypeRevision::fromMinorVersion(Minor minorVersion)
+
+    Produces a QTypeRevision from the given \a minorVersion with an invalid major
+    version. \a minorVersion needs to be a valid segment.
+
+    \sa isValidSegment()
+*/
+
+/*!
+    \fn template <typename Integer> static QTypeRevision QTypeRevision::fromEncodedVersion(Integer value)
+
+    Produces a QTypeRevision from the given \a value. \a value encodes both the
+    minor and major versions in the least significant and second least
+    significant byte, respectively.
+
+    \a value must not have any bits outside the least significant two bytes set.
+    \c Integer needs to be at least 16 bits wide, and must not have a sign bit
+    in the least significant 16 bits.
+
+    \sa toEncodedVersion()
+*/
+
+/*!
+    \fn static QTypeRevision QTypeRevision::zero()
+
+    Produces a QTypeRevision with major and minor version \c{0}.
+*/
+
+/*!
+    \fn bool QTypeRevision::hasMajorVersion() const
+
+    Returns true if the major version is known, otherwise false.
+
+    \sa majorVersion(), hasMinorVersion()
+*/
+
+/*!
+    \fn quint8 QTypeRevision::majorVersion() const
+
+    Returns the major version encoded in the revision.
+
+    \sa hasMajorVersion(), minorVersion()
+*/
+
+/*!
+    \fn bool QTypeRevision::hasMinorVersion() const
+
+    Returns true if the minor version is known, otherwise false.
+
+    \sa minorVersion(), hasMajorVersion()
+*/
 
+/*!
+    \fn quint8 QTypeRevision::minorVersion() const
+
+    Returns the minor version encoded in the revision.
+
+    \sa hasMinorVersion(), majorVersion()
+*/
+
+/*!
+    \fn bool QTypeRevision::isValid() const
+
+    Returns true if the major version or the minor version is known,
+    otherwise false.
+
+    \sa hasMajorVersion(), hasMinorVersion()
+*/
+
+/*!
+    \fn template<typename Integer> Integer QTypeRevision::toEncodedVersion() const
+
+    Transforms the revision into an integer value, encoding the minor
+    version into the least significant byte, and the major version into
+    the second least significant byte.
+
+    \c Integer needs to be at  least 16 bits wide, and must not have a sign bit
+    in the least significant 16 bits.
+
+    \sa fromEncodedVersion()
+*/
+
+#ifndef QT_NO_DATASTREAM
+/*!
+   \fn QDataStream& operator<<(QDataStream &out, const QTypeRevision &revision)
+   \relates QTypeRevision
+   \since 6.0
+
+   Writes the revision \a revision to stream \a out.
+ */
+QDataStream& operator<<(QDataStream &out, const QTypeRevision &revision)
+{
+    return out << revision.toEncodedVersion<quint16>();
+}
+
+/*!
+   \fn QDataStream& operator>>(QDataStream &in, QTypeRevision &revision)
+   \relates QTypeRevision
+   \since 6.0
+
+   Reads a revision from stream \a in and stores it in \a revision.
+ */
+QDataStream& operator>>(QDataStream &in, QTypeRevision &revision)
+{
+    quint16 value;
+    in >> value;
+    revision = QTypeRevision::fromEncodedVersion(value);
+    return in;
+}
+#endif
+
+#ifndef QT_NO_DEBUG_STREAM
+QDebug operator<<(QDebug debug, const QTypeRevision &revision)
+{
+    QDebugStateSaver saver(debug);
+    if (revision.hasMajorVersion()) {
+        if (revision.hasMinorVersion())
+            debug.nospace() << revision.majorVersion() << '.' << revision.minorVersion();
+        else
+            debug.nospace().noquote() << revision.majorVersion() << ".x";
+    } else {
+        if (revision.hasMinorVersion())
+            debug << revision.minorVersion();
+        else
+            debug.noquote() << "invalid";
+    }
+    return debug;
+}
+#endif
+
+/*!
+    \fn uint qHash(const QTypeRevision &key, uint seed)
+    \relates QHash
+    \since 6.0
+
+    Returns the hash value for the \a key, using \a seed to seed the
+    calculation.
+*/
+uint qHash(const QTypeRevision &key, uint seed)
+{
+    return qHash(key.toEncodedVersion<quint16>(), seed);
+}
+
+QT_END_NAMESPACE
diff --git a/src/corelib/tools/qversionnumber.h b/src/corelib/tools/qversionnumber.h
index d43b86ba51..03a27548b8 100644
--- a/src/corelib/tools/qversionnumber.h
+++ b/src/corelib/tools/qversionnumber.h
@@ -309,8 +309,159 @@ Q_REQUIRED_RESULT inline bool operator==(const QVersionNumber &lhs, const QVersi
 Q_REQUIRED_RESULT inline bool operator!=(const QVersionNumber &lhs, const QVersionNumber &rhs) noexcept
 { return QVersionNumber::compare(lhs, rhs) != 0; }
 
+class QTypeRevision;
+Q_CORE_EXPORT uint qHash(const QTypeRevision &key, uint seed = 0);
+
+#ifndef QT_NO_DATASTREAM
+Q_CORE_EXPORT QDataStream& operator<<(QDataStream &out, const QTypeRevision &revision);
+Q_CORE_EXPORT QDataStream& operator>>(QDataStream &in, QTypeRevision &revision);
+#endif
+
+class QTypeRevision
+{
+public:
+    template<typename Integer>
+    using if_valid_segment_type = typename std::enable_if<
+            std::is_integral<Integer>::value, bool>::type;
+
+    template<typename Integer>
+    using if_valid_value_type = typename std::enable_if<
+            std::is_integral<Integer>::value
+            && (sizeof(Integer) > sizeof(quint16)
+                || (sizeof(Integer) == sizeof(quint16)
+                    && !std::is_signed<Integer>::value)), bool>::type;
+
+    template<typename Integer, if_valid_segment_type<Integer> = true>
+    static constexpr bool isValidSegment(Integer segment)
+    {
+        return segment >= Integer(0) && segment < Integer(SegmentUnknown);
+    }
+
+    static constexpr bool isValidSegment(qint8 segment) { return segment >= 0; }
+
+    template<typename Major, typename Minor,
+             if_valid_segment_type<Major> = true,
+             if_valid_segment_type<Minor> = true>
+    static constexpr QTypeRevision fromVersion(Major majorVersion, Minor minorVersion)
+    {
+        return Q_ASSERT(isValidSegment(majorVersion)),
+               Q_ASSERT(isValidSegment(minorVersion)),
+               QTypeRevision(quint8(majorVersion), quint8(minorVersion));
+    }
+
+    template<typename Major, if_valid_segment_type<Major> = true>
+    static constexpr QTypeRevision fromMajorVersion(Major majorVersion)
+    {
+        return Q_ASSERT(isValidSegment(majorVersion)),
+               QTypeRevision(quint8(majorVersion), SegmentUnknown);
+    }
+
+    template<typename Minor, if_valid_segment_type<Minor> = true>
+    static constexpr QTypeRevision fromMinorVersion(Minor minorVersion)
+    {
+        return Q_ASSERT(isValidSegment(minorVersion)),
+               QTypeRevision(SegmentUnknown, quint8(minorVersion));
+    }
+
+    template<typename Integer, if_valid_value_type<Integer> = true>
+    static constexpr QTypeRevision fromEncodedVersion(Integer value)
+    {
+        return Q_ASSERT((value & ~Integer(0xffff)) == Integer(0)),
+               QTypeRevision((value & Integer(0xff00)) >> 8, value & Integer(0xff));
+    }
+
+    static constexpr QTypeRevision zero() { return QTypeRevision(0, 0); }
+
+    constexpr QTypeRevision() = default;
+
+    constexpr bool hasMajorVersion() const { return m_majorVersion != SegmentUnknown; }
+    constexpr quint8 majorVersion() const { return m_majorVersion; }
+
+    constexpr bool hasMinorVersion() const { return m_minorVersion != SegmentUnknown; }
+    constexpr quint8 minorVersion() const { return m_minorVersion; }
+
+    constexpr bool isValid() const { return hasMajorVersion() || hasMinorVersion(); }
+
+    template<typename Integer, if_valid_value_type<Integer> = true>
+    constexpr Integer toEncodedVersion() const
+    {
+        return Integer(m_majorVersion << 8) | Integer(m_minorVersion);
+    }
+
+private:
+    enum { SegmentUnknown = quint8(~0U) };
+
+#if Q_BYTE_ORDER == Q_LITTLE_ENDIAN
+    constexpr QTypeRevision(quint8 major, quint8 minor)
+        : m_minorVersion(minor), m_majorVersion(major) {}
+
+    quint8 m_minorVersion = SegmentUnknown;
+    quint8 m_majorVersion = SegmentUnknown;
+#else
+    constexpr QTypeRevision(quint8 major, quint8 minor)
+        : m_majorVersion(major), m_minorVersion(minor) {}
+
+    quint8 m_majorVersion = SegmentUnknown;
+    quint8 m_minorVersion = SegmentUnknown;
+#endif
+};
+
+inline constexpr bool operator==(QTypeRevision lhs, QTypeRevision rhs)
+{
+    return lhs.toEncodedVersion<quint16>() == rhs.toEncodedVersion<quint16>();
+}
+
+inline constexpr bool operator!=(QTypeRevision lhs, QTypeRevision rhs)
+{
+    return lhs.toEncodedVersion<quint16>() != rhs.toEncodedVersion<quint16>();
+}
+
+inline constexpr bool operator<(QTypeRevision lhs, QTypeRevision rhs)
+{
+    return (!lhs.hasMajorVersion() && rhs.hasMajorVersion())
+            // non-0 major > unspecified major > major 0
+            ? rhs.majorVersion() != 0
+            : ((lhs.hasMajorVersion() && !rhs.hasMajorVersion())
+               // major 0 < unspecified major < non-0 major
+               ? lhs.majorVersion() == 0
+               : (lhs.majorVersion() != rhs.majorVersion()
+                  // both majors specified and non-0
+                  ? lhs.majorVersion() < rhs.majorVersion()
+                  : ((!lhs.hasMinorVersion() && rhs.hasMinorVersion())
+                     // non-0 minor > unspecified minor > minor 0
+                     ? rhs.minorVersion() != 0
+                     : ((lhs.hasMinorVersion() && !rhs.hasMinorVersion())
+                        // minor 0 < unspecified minor < non-0 minor
+                        ? lhs.minorVersion() == 0
+                        // both minors specified and non-0
+                        : lhs.minorVersion() < rhs.minorVersion()))));
+}
+
+inline constexpr bool operator>(QTypeRevision lhs, QTypeRevision rhs)
+{
+    return lhs != rhs && !(lhs < rhs);
+}
+
+inline constexpr bool operator<=(QTypeRevision lhs, QTypeRevision rhs)
+{
+    return lhs == rhs || lhs < rhs;
+}
+
+inline constexpr bool operator>=(QTypeRevision lhs, QTypeRevision rhs)
+{
+    return lhs == rhs || !(lhs < rhs);
+}
+
+Q_STATIC_ASSERT(sizeof(QTypeRevision) == 2);
+Q_DECLARE_TYPEINFO(QTypeRevision, Q_MOVABLE_TYPE);
+
+#ifndef QT_NO_DEBUG_STREAM
+Q_CORE_EXPORT QDebug operator<<(QDebug, const QTypeRevision &revision);
+#endif
+
 QT_END_NAMESPACE
 
 Q_DECLARE_METATYPE(QVersionNumber)
+Q_DECLARE_METATYPE(QTypeRevision)
 
 #endif //QVERSIONNUMBER_H