2 files changed, 21 insertions, 8 deletions

diff --git a/src/qml/types/qqmlbind.cpp b/src/qml/types/qqmlbind.cpp
index 9d305cd24c..36de16a818 100644
--- a/src/qml/types/qqmlbind.cpp
+++ b/src/qml/types/qqmlbind.cpp
@@ -78,7 +78,7 @@ public:
     QQmlNullableValue<bool> when;
     QPointer<QObject> obj;
     QString propName;
-    QQmlNullableValue<QVariant> value;
+    QQmlNullableValue<QJSValue> value;
     QQmlProperty prop;
     QQmlAbstractBinding::Ptr prevBind;
     QV4::PersistentValue v4Value;
@@ -293,13 +293,13 @@ void QQmlBind::setProperty(const QString &p)
     The value to be set on the target object and property.  This can be a
     constant (which isn't very useful), or a bound expression.
 */
-QVariant QQmlBind::value() const
+QJSValue QQmlBind::value() const
 {
     Q_D(const QQmlBind);
     return d->value.value;
 }
 
-void QQmlBind::setValue(const QVariant &v)
+void QQmlBind::setValue(const QJSValue &v)
 {
     Q_D(QQmlBind);
     d->value = v;
@@ -359,7 +359,8 @@ void QQmlBind::setDelayed(bool delayed)
     \li Binding.RestoreBindingOrValue The original value is always restored.
     \endlist
 
-    The default value is Binding.RestoreBinding.
+    \warning The default value is Binding.RestoreBinding. This will change in
+    Qt 5.15 to Binding.RestoreBindingOrValue.
 
     If you rely on any specific behavior regarding the restoration of plain
     values when bindings get disabled you should migrate to explicitly set the
@@ -456,11 +457,23 @@ void QQmlBind::eval()
                     Q_ASSERT(vmemo);
                     vmemo->setVMEProperty(propPriv->core.coreIndex(), *d->v4Value.valueRef());
                     d->clearPrev();
+                } else if (!d->restoreModeExplicit) {
+                    qmlWarning(this)
+                            << "Not restoring previous value because restoreMode has not been set."
+                            << "This behavior is deprecated."
+                            << "In Qt < 5.15 the default is Binding.RestoreBinding."
+                            << "In Qt >= 5.15 the default is Binding.RestoreBindingOrValue.";
                 }
             } else if (d->prevIsVariant) {
                 if (d->restoreValue) {
                     d->prop.write(d->prevValue);
                     d->clearPrev();
+                } else if (!d->restoreModeExplicit) {
+                    qmlWarning(this)
+                            << "Not restoring previous value because restoreMode has not been set."
+                            << "This behavior is deprecated."
+                            << "In Qt < 5.15 the default is Binding.RestoreBinding."
+                            << "In Qt >= 5.15 the default is Binding.RestoreBindingOrValue.";
                 }
             }
             return;
@@ -489,7 +502,7 @@ void QQmlBind::eval()
         QQmlPropertyPrivate::removeBinding(d->prop);
     }
 
-    d->prop.write(d->value.value);
+    d->prop.write(d->value.value.toVariant());
 }
 
 QT_END_NAMESPACE
diff --git a/src/qml/types/qqmlbind_p.h b/src/qml/types/qqmlbind_p.h
index e7c7e01a0d..a100b1552c 100644
--- a/src/qml/types/qqmlbind_p.h
+++ b/src/qml/types/qqmlbind_p.h
@@ -75,7 +75,7 @@ private:
     Q_INTERFACES(QQmlPropertyValueSource)
     Q_PROPERTY(QObject *target READ object WRITE setObject)
     Q_PROPERTY(QString property READ property WRITE setProperty)
-    Q_PROPERTY(QVariant value READ value WRITE setValue)
+    Q_PROPERTY(QJSValue value READ value WRITE setValue)
     Q_PROPERTY(bool when READ when WRITE setWhen)
     Q_PROPERTY(bool delayed READ delayed WRITE setDelayed REVISION 8)
     Q_PROPERTY(RestorationMode restoreMode READ restoreMode WRITE setRestoreMode
@@ -96,8 +96,8 @@ public:
     QString property() const;
     void setProperty(const QString &);
 
-    QVariant value() const;
-    void setValue(const QVariant &);
+    QJSValue value() const;
+    void setValue(const QJSValue &);
 
     bool delayed() const;
     void setDelayed(bool);