3 files changed, 31 insertions, 29 deletions

diff --git a/src/corelib/kernel/qproperty.h b/src/corelib/kernel/qproperty.h
index 8f050327d5..e43f59053d 100644
--- a/src/corelib/kernel/qproperty.h
+++ b/src/corelib/kernel/qproperty.h
@@ -117,10 +117,8 @@ private:
 class Q_CORE_EXPORT QUntypedPropertyBinding
 {
 public:
-    // Returns either a boolean to indicate value change or an error.
-    using BindingEvaluationResult = std::variant<bool, QPropertyBindingError>;
-    // returns true if value changed, false if the binding evaluation lead to the same value as the property
-    // already has.
+    using BindingEvaluationResult = QPropertyBindingError;
+    // writes binding result into dataPtr
     using BindingEvaluationFunction = std::function<BindingEvaluationResult(const QMetaType &metaType, void *dataPtr)>;
 
     QUntypedPropertyBinding();
@@ -160,13 +158,11 @@ class QPropertyBinding : public QUntypedPropertyBinding
 
             if (auto valuePtr = std::get_if<PropertyType>(&result)) {
                 PropertyType *propertyPtr = reinterpret_cast<PropertyType *>(dataPtr);
-                if (*propertyPtr == *valuePtr)
-                    return false;
                 *propertyPtr = std::move(*valuePtr);
-                return true;
+                return {};
             }
 
-            return false;
+            return {};
         }
     };
 
diff --git a/src/corelib/kernel/qpropertybinding.cpp b/src/corelib/kernel/qpropertybinding.cpp
index 358977e63e..29b1a4a69a 100644
--- a/src/corelib/kernel/qpropertybinding.cpp
+++ b/src/corelib/kernel/qpropertybinding.cpp
@@ -41,6 +41,7 @@
 #include "qproperty_p.h"
 
 #include <QScopedValueRollback>
+#include <QVariant>
 
 QT_BEGIN_NAMESPACE
 
@@ -80,25 +81,34 @@ bool QPropertyBindingPrivate::evaluateIfDirtyAndReturnTrueIfValueChanged()
 
     BindingEvaluationState evaluationFrame(this);
 
+    QPropertyBindingError evalError;
     QUntypedPropertyBinding::BindingEvaluationResult result;
     bool changed = false;
     if (metaType.id() == QMetaType::Bool) {
         auto propertyPtr = reinterpret_cast<QPropertyBase *>(propertyDataPtr);
-        bool temp = propertyPtr->extraBit();
-        result = evaluationFunction(metaType, &temp);
-        if (auto changedPtr = std::get_if<bool>(&result)) {
-            changed = *changedPtr;
-            if (changed)
-                propertyPtr->setExtraBit(temp);
+        bool newValue = false;
+        evalError = evaluationFunction(metaType, &newValue);
+        if (evalError.type() == QPropertyBindingError::NoError) {
+            if (propertyPtr->extraBit() != newValue) {
+                propertyPtr->setExtraBit(newValue);
+                changed = true;
+            }
         }
     } else {
-        result = evaluationFunction(metaType, propertyDataPtr);
-        if (auto changedPtr = std::get_if<bool>(&result))
-            changed = *changedPtr;
+        QVariant resultVariant(metaType.id(), nullptr);
+        evalError = evaluationFunction(metaType, resultVariant.data());
+        if (evalError.type() == QPropertyBindingError::NoError) {
+            int compareResult = 0;
+            if (!QMetaType::compare(propertyDataPtr, resultVariant.constData(), metaType.id(), &compareResult) || compareResult != 0) {
+                changed = true;
+                metaType.destruct(propertyDataPtr);
+                metaType.construct(propertyDataPtr, resultVariant.constData());
+            }
+        }
     }
 
-    if (auto errorPtr = std::get_if<QPropertyBindingError>(&result))
-        error = std::move(*errorPtr);
+    if (evalError.type() != QPropertyBindingError::NoError)
+        error = evalError;
 
     dirty = false;
     return changed;
diff --git a/tests/auto/corelib/kernel/qproperty/tst_qproperty.cpp b/tests/auto/corelib/kernel/qproperty/tst_qproperty.cpp
index cc04c2f1b5..488ecacb8d 100644
--- a/tests/auto/corelib/kernel/qproperty/tst_qproperty.cpp
+++ b/tests/auto/corelib/kernel/qproperty/tst_qproperty.cpp
@@ -617,22 +617,20 @@ void tst_QProperty::genericPropertyBinding()
 
     {
         QUntypedPropertyBinding doubleBinding(QMetaType::fromType<double>(),
-                                              [](const QMetaType &, void *) -> bool {
+                                              [](const QMetaType &, void *) -> QUntypedPropertyBinding::BindingEvaluationResult {
             Q_ASSERT(false);
-            return false;
+            return QPropertyBindingError::NoError;
         }, QPropertyBindingSourceLocation());
         QVERIFY(!property.setBinding(doubleBinding));
     }
 
     QUntypedPropertyBinding intBinding(QMetaType::fromType<int>(),
-                                    [](const QMetaType &metaType, void *dataPtr) -> bool {
+                                    [](const QMetaType &metaType, void *dataPtr) -> QUntypedPropertyBinding::BindingEvaluationResult {
         Q_ASSERT(metaType.id() == qMetaTypeId<int>());
 
         int *intPtr = reinterpret_cast<int*>(dataPtr);
-        if (*intPtr == 100)
-            return false;
         *intPtr = 100;
-        return true;
+        return QPropertyBindingError::NoError;
     }, QPropertyBindingSourceLocation());
 
     QVERIFY(property.setBinding(intBinding));
@@ -647,12 +645,10 @@ void tst_QProperty::genericPropertyBindingBool()
     QVERIFY(!property.value());
 
     QUntypedPropertyBinding boolBinding(QMetaType::fromType<bool>(),
-            [](const QMetaType &, void *dataPtr) -> bool {
+            [](const QMetaType &, void *dataPtr) -> QUntypedPropertyBinding::BindingEvaluationResult {
         auto boolPtr = reinterpret_cast<bool *>(dataPtr);
-        if (*boolPtr)
-            return false;
         *boolPtr = true;
-        return true;
+        return {};
     }, QPropertyBindingSourceLocation());
     QVERIFY(property.setBinding(boolBinding));