Fix QMetaProperty::write so it tries to register a property type.

We can not assume that the property type is always registered, because
QVariant argument may contain an instance of a different type.

Change-Id: I4fc9593b826e13c401dbdacec4d60db36edc7102
Reviewed-by: Olivier Goffart <ogoffart@woboq.com>

2 files changed, 55 insertions, 2 deletions

diff --git a/src/corelib/kernel/qmetaobject.cpp b/src/corelib/kernel/qmetaobject.cpp
index bf31ef9151..3e2fb46143 100644
--- a/src/corelib/kernel/qmetaobject.cpp
+++ b/src/corelib/kernel/qmetaobject.cpp
@@ -3027,9 +3027,11 @@ bool QMetaProperty::write(QObject *object, const QVariant &value) const
         else {
             typeName = rawStringData(mobj, typeInfo & TypeNameIndexMask);
             t = QMetaType::type(typeName);
+            if (t == QMetaType::UnknownType)
+                t = registerPropertyType();
+            if (t == QMetaType::UnknownType)
+                return false;
         }
-        if (t == QMetaType::UnknownType)
-            return false;
         if (t != QMetaType::QVariant && t != (uint)value.userType() && (t < QMetaType::User && !v.convert((QVariant::Type)t)))
             return false;
     }
diff --git a/tests/auto/corelib/kernel/qmetaproperty/tst_qmetaproperty.cpp b/tests/auto/corelib/kernel/qmetaproperty/tst_qmetaproperty.cpp
index 941abf9039..df76dfc47f 100644
--- a/tests/auto/corelib/kernel/qmetaproperty/tst_qmetaproperty.cpp
+++ b/tests/auto/corelib/kernel/qmetaproperty/tst_qmetaproperty.cpp
@@ -52,6 +52,7 @@ private slots:
     void isConstant();
     void isFinal();
     void gadget();
+    void readAndWriteWithLazyRegistration();
 
 public:
     enum EnumType { EnumType1 };
@@ -131,6 +132,56 @@ void tst_QMetaProperty::gadget()
     }
 }
 
+struct CustomReadObject : QObject
+{
+    Q_OBJECT
+};
+
+struct CustomWriteObject : QObject
+{
+    Q_OBJECT
+};
+
+struct CustomWriteObjectChild : CustomWriteObject
+{
+    Q_OBJECT
+};
+
+struct TypeLazyRegistration : QObject
+{
+    Q_OBJECT
+    Q_PROPERTY(CustomReadObject *read MEMBER _read)
+    Q_PROPERTY(CustomWriteObject *write MEMBER _write)
+
+    CustomReadObject *_read;
+    CustomWriteObject *_write;
+
+public:
+    TypeLazyRegistration()
+        : _read()
+        , _write()
+    {}
+};
+
+void tst_QMetaProperty::readAndWriteWithLazyRegistration()
+{
+    QCOMPARE(QMetaType::type("CustomReadObject*"), int(QMetaType::UnknownType));
+    QCOMPARE(QMetaType::type("CustomWriteObject*"), int(QMetaType::UnknownType));
+
+    TypeLazyRegistration o;
+    QVERIFY(o.property("read").isValid());
+    QVERIFY(QMetaType::type("CustomReadObject*") != QMetaType::UnknownType);
+    QCOMPARE(QMetaType::type("CustomWriteObject*"), int(QMetaType::UnknownType));
+
+    CustomWriteObjectChild data;
+    QVariant value = QVariant::fromValue(&data); // this register CustomWriteObjectChild
+    // check if base classes are not registered automatically, otherwise this test would be meaningless
+    QCOMPARE(QMetaType::type("CustomWriteObject*"), int(QMetaType::UnknownType));
+    QVERIFY(o.setProperty("write", value));
+    QVERIFY(QMetaType::type("CustomWriteObject*") != QMetaType::UnknownType);
+    QCOMPARE(o.property("write").value<CustomWriteObjectChild*>(), &data);
+}
+
 
 QTEST_MAIN(tst_QMetaProperty)
 #include "tst_qmetaproperty.moc"