1 files changed, 9 insertions, 6 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()