4 files changed, 35 insertions, 28 deletions
diff --git a/src/corelib/thread/qfutureinterface.cpp b/src/corelib/thread/qfutureinterface.cpp
index 76af95e3a3..22c8a48411 100644
--- a/src/corelib/thread/qfutureinterface.cpp
+++ b/src/corelib/thread/qfutureinterface.cpp
@@ -84,7 +84,7 @@ QFutureInterfaceBase::QFutureInterfaceBase(const QFutureInterfaceBase &other)
 
 QFutureInterfaceBase::~QFutureInterfaceBase()
 {
-    if (!d->refCount.deref())
+    if (d && !d->refCount.deref())
         delete d;
 }
 
@@ -394,6 +394,9 @@ bool QFutureInterfaceBase::queryState(State state) const
 
 int QFutureInterfaceBase::loadState() const
 {
+    // Used from ~QPromise, so this check is needed
+    if (!d)
+        return QFutureInterfaceBase::State::NoState;
     return d->state.loadRelaxed();
 }
 
@@ -568,13 +571,12 @@ const QtPrivate::ResultStoreBase &QFutureInterfaceBase::resultStoreBase() const
 
 QFutureInterfaceBase &QFutureInterfaceBase::operator=(const QFutureInterfaceBase &other)
 {
-    other.d->refCount.ref();
-    if (!d->refCount.deref())
-        delete d;
-    d = other.d;
+    QFutureInterfaceBase copy(other);
+    swap(copy);
     return *this;
 }
 
+// ### Qt 7: inline
 void QFutureInterfaceBase::swap(QFutureInterfaceBase &other) noexcept
 {
     qSwap(d, other.d);
@@ -587,7 +589,8 @@ bool QFutureInterfaceBase::refT() const
 
 bool QFutureInterfaceBase::derefT() const
 {
-    return d->refCount.derefT();
+    // Called from ~QFutureInterface
+    return !d || d->refCount.derefT();
 }
 
 void QFutureInterfaceBase::reset()
diff --git a/src/corelib/thread/qfutureinterface.h b/src/corelib/thread/qfutureinterface.h
index 62875c5ef9..4da5b36eae 100644
--- a/src/corelib/thread/qfutureinterface.h
+++ b/src/corelib/thread/qfutureinterface.h
@@ -95,6 +95,10 @@ public:
 
     QFutureInterfaceBase(State initialState = NoState);
     QFutureInterfaceBase(const QFutureInterfaceBase &other);
+    QFutureInterfaceBase(QFutureInterfaceBase &&other) noexcept
+        : d(std::exchange(other.d, nullptr)) {}
+    QFutureInterfaceBase &operator=(const QFutureInterfaceBase &other);
+    QT_MOVE_ASSIGNMENT_OPERATOR_IMPL_VIA_MOVE_AND_SWAP(QFutureInterfaceBase)
     virtual ~QFutureInterfaceBase();
 
     // reporting functions available to the engine author:
@@ -165,8 +169,8 @@ public:
 
     inline bool operator==(const QFutureInterfaceBase &other) const { return d == other.d; }
     inline bool operator!=(const QFutureInterfaceBase &other) const { return d != other.d; }
-    QFutureInterfaceBase &operator=(const QFutureInterfaceBase &other);
 
+    // ### Qt 7: inline
     void swap(QFutureInterfaceBase &other) noexcept;
 
 protected:
@@ -206,6 +210,11 @@ protected:
     bool isRunningOrPending() const;
 };
 
+inline void swap(QFutureInterfaceBase &lhs, QFutureInterfaceBase &rhs) noexcept
+{
+    lhs.swap(rhs);
+}
+
 template <typename T>
 class QFutureInterface : public QFutureInterfaceBase
 {
@@ -221,6 +230,16 @@ public:
         refT();
     }
     QFutureInterface(const QFutureInterfaceBase &dd) : QFutureInterfaceBase(dd) { refT(); }
+    QFutureInterface(QFutureInterfaceBase &&dd) : QFutureInterfaceBase(std::move(dd)) { refT(); }
+    QFutureInterface &operator=(const QFutureInterface &other)
+    {
+        QFutureInterface copy(other);
+        swap(copy);
+        return *this;
+    }
+    QFutureInterface(QFutureInterface &&other) = default;
+    QT_MOVE_ASSIGNMENT_OPERATOR_IMPL_VIA_MOVE_AND_SWAP(QFutureInterface)
+
     ~QFutureInterface()
     {
         if (!derefT())
@@ -230,15 +249,6 @@ public:
     static QFutureInterface canceledResult()
     { return QFutureInterface(State(Started | Finished | Canceled)); }
 
-    QFutureInterface &operator=(const QFutureInterface &other)
-    {
-        other.refT();
-        if (!derefT())
-            resultStoreBase().template clear<T>();
-        QFutureInterfaceBase::operator=(other);
-        return *this;
-    }
-
     inline QFuture<T> future(); // implemented in qfuture.h
 
     inline bool reportResult(const T *result, int index = -1);
diff --git a/src/corelib/thread/qpromise.h b/src/corelib/thread/qpromise.h
index e453f29b6a..24b0cd1e80 100644
--- a/src/corelib/thread/qpromise.h
+++ b/src/corelib/thread/qpromise.h
@@ -58,17 +58,10 @@ class QPromise
 public:
     QPromise() = default;
     Q_DISABLE_COPY(QPromise)
-    QPromise(QPromise<T> &&other) : d(other.d)
-    {
-        other.d = QFutureInterface<T>();
-    }
-    QPromise(QFutureInterface<T> &other) : d(other) {}
-    QPromise& operator=(QPromise<T> &&other)
-    {
-        QPromise<T> tmp(std::move(other));
-        tmp.swap(*this);
-        return *this;
-    }
+    QPromise(QPromise<T> &&other) = default;
+    QPromise(const QFutureInterface<T> &other) : d(other) {}
+    QPromise(QFutureInterface<T> &&other) noexcept : d(std::move(other)) {}
+    QT_MOVE_ASSIGNMENT_OPERATOR_IMPL_VIA_MOVE_AND_SWAP(QPromise)
     ~QPromise()
     {
         const int state = d.loadState();
diff --git a/src/corelib/thread/qpromise.qdoc b/src/corelib/thread/qpromise.qdoc
index 78182323be..f051faf9f9 100644
--- a/src/corelib/thread/qpromise.qdoc
+++ b/src/corelib/thread/qpromise.qdoc
@@ -78,7 +78,8 @@
     \sa operator=()
 */
 
-/*! \fn template <typename T> QPromise<T>::QPromise(QFutureInterface<T> &other)
+/*! \fn template <typename T> QPromise<T>::QPromise(const QFutureInterface<T> &other)
+    \fn template <typename T> QPromise<T>::QPromise(QFutureInterface<T> &&other)
 
     \internal
     Constructs a QPromise with a passed QFutureInterface \a other.