Align QVariant::UserType and QMetaType::User

There is no point in keeping separate values which should mean the
same.

QVariant::UserType was used also to construct a valid, null QVariant,
containing an instance of unknown custom type. The concept was strange
and useless as there was no operation that could be done on such
QVariant. Therefore it was dropped.

Please note that the patch slightly changes behavior of different
functions accepting a type id as parameter. Before QVariant::UserType
was an invalid type from QMetaType perspective (id 127 was not assigned
to any built-in type), but QMetaType::User points to the first registered
custom type.

Change-Id: I5c7d541a9affdcdacf53a4eda2272bdafaa87b71
Reviewed-by: Kent Hansen <kent.hansen@nokia.com>
Reviewed-by: Lars Knoll <lars.knoll@nokia.com>
Reviewed-by: João Abecasis <joao.abecasis@nokia.com>
Reviewed-by: Andrew Stanley-Jones <andrew.stanley-jones@nokia.com>
Reviewed-by: Aaron Kennedy <aaron.kennedy@nokia.com>

8 files changed, 29 insertions, 34 deletions

diff --git a/dist/changes-5.0.0 b/dist/changes-5.0.0
index fc5bebd11d..280b5d93f9 100644
--- a/dist/changes-5.0.0
+++ b/dist/changes-5.0.0
@@ -437,6 +437,13 @@ Qt for Windows CE
      cause an abort().
 
 
+- QVariant
+
+  * Definition of QVariant::UserType changed. Currently it is the same as
+    QMetaType::User, which means that it points to the first registered custom
+    type, instead of a nonexistent type.
+
+
 - QMessageBox
 
      * The static function QMessageBox::question has changed the default argument
diff --git a/src/corelib/kernel/qmetaobject.cpp b/src/corelib/kernel/qmetaobject.cpp
index 400fe54c7f..7975fc2628 100644
--- a/src/corelib/kernel/qmetaobject.cpp
+++ b/src/corelib/kernel/qmetaobject.cpp
@@ -2243,9 +2243,8 @@ QVariant QMetaProperty::read(const QObject *object) const
             t = QMetaType::type(typeName);
         if (t == QVariant::Invalid)
             t = QVariant::nameToType(typeName);
-        if (t == QVariant::Invalid || t == QVariant::UserType) {
-            if (t == QVariant::Invalid)
-                qWarning("QMetaProperty::read: Unable to handle unregistered datatype '%s' for property '%s::%s'", typeName, mobj->className(), name());
+        if (t == QVariant::Invalid) {
+            qWarning("QMetaProperty::read: Unable to handle unregistered datatype '%s' for property '%s::%s'", typeName, mobj->className(), name());
             return QVariant();
         }
     }
diff --git a/src/corelib/kernel/qvariant.cpp b/src/corelib/kernel/qvariant.cpp
index cfaf22c146..4197fe9093 100644
--- a/src/corelib/kernel/qvariant.cpp
+++ b/src/corelib/kernel/qvariant.cpp
@@ -1608,7 +1608,7 @@ QVariant::Type QVariant::nameToType(const char *name)
         return Invalid;
 
     int metaType = QMetaType::type(name);
-    return metaType <= int(LastGuiType) ? QVariant::Type(metaType) : UserType;
+    return metaType <= int(UserType) ? QVariant::Type(metaType) : UserType;
 }
 
 #ifndef QT_NO_DATASTREAM
@@ -1670,7 +1670,9 @@ void QVariant::load(QDataStream &s)
             return;
         typeId = mapIdFromQt3ToCurrent[typeId];
     } else if (s.version() < QDataStream::Qt_5_0) {
-        if (typeId >= 128 && typeId != QVariant::UserType) {
+        if (typeId == 127 /* QVariant::UserType */) {
+            typeId = QMetaType::User;
+        } else if (typeId >= 128 && typeId != QVariant::UserType) {
             // In Qt4 id == 128 was FirstExtCoreType. In Qt5 ExtCoreTypes set was merged to CoreTypes
             // by moving all ids down by 97.
             typeId -= 97;
@@ -1741,7 +1743,9 @@ void QVariant::save(QDataStream &s) const
             return;
         }
     } else if (s.version() < QDataStream::Qt_5_0) {
-        if (typeId >= 128 - 97 && typeId <= LastCoreType) {
+        if (typeId == QMetaType::User) {
+            typeId = 127; // QVariant::UserType had this value in Qt4
+        } else if (typeId >= 128 - 97 && typeId <= LastCoreType) {
             // In Qt4 id == 128 was FirstExtCoreType. In Qt5 ExtCoreTypes set was merged to CoreTypes
             // by moving all ids down by 97.
             typeId += 97;
@@ -1762,7 +1766,7 @@ void QVariant::save(QDataStream &s) const
     s << typeId;
     if (s.version() >= QDataStream::Qt_4_2)
         s << qint8(d.is_null);
-    if (typeId == QVariant::UserType) {
+    if (d.type >= QVariant::UserType) {
         s << QMetaType::typeName(userType());
     }
 
diff --git a/src/corelib/kernel/qvariant.h b/src/corelib/kernel/qvariant.h
index 07ef4dc41e..b61b0cc33c 100644
--- a/src/corelib/kernel/qvariant.h
+++ b/src/corelib/kernel/qvariant.h
@@ -153,7 +153,7 @@ class Q_CORE_EXPORT QVariant
         Icon = QMetaType::QIcon,
         SizePolicy = QMetaType::QSizePolicy,
 
-        UserType = 127,
+        UserType = QMetaType::User,
         LastType = 0xffffffff // need this so that gcc >= 3.4 allocates 32 bits for Type
     };
 
diff --git a/src/corelib/kernel/qvariant_p.h b/src/corelib/kernel/qvariant_p.h
index 7065bcfd6b..30159f1831 100644
--- a/src/corelib/kernel/qvariant_p.h
+++ b/src/corelib/kernel/qvariant_p.h
@@ -348,14 +348,6 @@ public:
 
     void delegate(const QMetaTypeSwitcher::UnknownType*)
     {
-        if (m_x->type == QVariant::UserType) {
-            // TODO get rid of it
-            // And yes! we can support historical magic, unkonwn/unconstructed user type isn't that
-            // awesome? this QVariant::isValid will be true!
-            m_x->is_null = !m_copy;
-            m_x->is_shared = false;
-            return;
-        }
         qWarning("Trying to construct an instance of an invalid type, type id: %i", m_x->type);
         m_x->type = QVariant::Invalid;
     }
@@ -406,8 +398,6 @@ public:
 
     void delegate(const QMetaTypeSwitcher::UnknownType*)
     {
-        if (m_d->type == QVariant::UserType)
-            return;
         qWarning("Trying to destruct an instance of an invalid type, type id: %i", m_d->type);
     }
     // Ignore nonconstructible type
@@ -454,10 +444,7 @@ public:
 
     void delegate(const QMetaTypeSwitcher::UnknownType*)
     {
-        if (m_d->type == QVariant::UserType)
-            m_debugStream.nospace() << "QVariant::UserType";
-        else
-            qWarning("Trying to stream an instance of an invalid type, type id: %i", m_d->type);
+        qWarning("Trying to stream an instance of an invalid type, type id: %i", m_d->type);
     }
     void delegate(const void*)
     {
diff --git a/tests/auto/corelib/kernel/qobject/tst_qobject.cpp b/tests/auto/corelib/kernel/qobject/tst_qobject.cpp
index 7f95f68075..4e7935be31 100644
--- a/tests/auto/corelib/kernel/qobject/tst_qobject.cpp
+++ b/tests/auto/corelib/kernel/qobject/tst_qobject.cpp
@@ -1704,6 +1704,7 @@ void tst_QObject::property()
     QVERIFY(!property.isEnumType());
     QCOMPARE(property.typeName(), "CustomType*");
     QCOMPARE(property.type(), QVariant::UserType);
+    QCOMPARE(property.userType(), qMetaTypeId<CustomType*>());
 
     CustomType *customPointer = 0;
     QVariant customVariant = object.property("custom");
@@ -1718,6 +1719,7 @@ void tst_QObject::property()
     QVERIFY(property.isWritable());
     QCOMPARE(property.typeName(), "CustomType*");
     QCOMPARE(property.type(), QVariant::UserType);
+    QCOMPARE(property.userType(), qMetaTypeId<CustomType*>());
 
     QVERIFY(object.setProperty("custom", customVariant));
     QCOMPARE(object.custom(), customPointer);
diff --git a/tests/auto/corelib/kernel/qvariant/tst_qvariant.cpp b/tests/auto/corelib/kernel/qvariant/tst_qvariant.cpp
index 2bf554dd78..f7bdfd800a 100644
--- a/tests/auto/corelib/kernel/qvariant/tst_qvariant.cpp
+++ b/tests/auto/corelib/kernel/qvariant/tst_qvariant.cpp
@@ -1842,10 +1842,6 @@ void tst_QVariant::operator_eq_eq_data()
 
         QTest::newRow("HashSecondLarger") << QVariant(hash1) << QVariant(hash2) << false;
     }
-
-    QTest::newRow( "UserType" ) << QVariant(QVariant::UserType) << QVariant(QVariant::UserType) << true;
-    QVariant mUserType(QVariant::UserType);
-    QTest::newRow( "Shared UserType" ) << mUserType << mUserType << true;
 }
 
 void tst_QVariant::operator_eq_eq()
@@ -1919,7 +1915,6 @@ void tst_QVariant::typeName_data()
     QTest::newRow("39") << int(QVariant::RectF) << QByteArray("QRectF");
     QTest::newRow("40") << int(QVariant::PointF) << QByteArray("QPointF");
     QTest::newRow("41") << int(QVariant::RegExp) << QByteArray("QRegExp");
-    QTest::newRow("42") << int(QVariant::UserType) << QByteArray();
     QTest::newRow("43") << int(QVariant::Matrix) << QByteArray("QMatrix");
     QTest::newRow("44") << int(QVariant::Transform) << QByteArray("QTransform");
     QTest::newRow("45") << int(QVariant::Hash) << QByteArray("QVariantHash");
@@ -2031,10 +2026,10 @@ void tst_QVariant::userType()
             qVariantSetValue(userVar, data);
 
             QCOMPARE(userVar.type(), QVariant::UserType);
+            QCOMPARE(userVar.userType(), qMetaTypeId<MyType>());
             QCOMPARE(userVar.typeName(), "MyType");
             QVERIFY(!userVar.isNull());
             QVERIFY(!userVar.canConvert(QVariant::String));
-            QVERIFY(!userVar.canConvert(QVariant::UserType));
 
             QVariant userVar2(userVar);
             QVERIFY(userVar == userVar2);
@@ -2060,10 +2055,10 @@ void tst_QVariant::userType()
             qVariantSetValue(userVar, &data);
 
             QCOMPARE(userVar.type(), QVariant::UserType);
+            QCOMPARE(userVar.userType(), qMetaTypeId<MyType*>());
             QCOMPARE(userVar.typeName(), "MyType*");
             QVERIFY(!userVar.isNull());
             QVERIFY(!userVar.canConvert(QVariant::String));
-            QVERIFY(!userVar.canConvert(QVariant::UserType));
 
             QVariant userVar2(userVar);
             QVERIFY(userVar == userVar2);
@@ -2696,7 +2691,7 @@ Q_DECLARE_METATYPE( MyClass )
 void tst_QVariant::loadUnknownUserType()
 {
     qRegisterMetaType<MyClass>("MyClass");
-    char data[] = {0, 0, 0, 127, 0, 0, 0, 0, 8, 77, 121, 67, 108, 97, 115, 115, 0};
+    char data[] = {0, 0, 1, 0, 0, 0, 0, 0, 8, 77, 121, 67, 108, 97, 115, 115, 0};
 
     QByteArray ba(data, sizeof(data));
     QDataStream ds(&ba, QIODevice::ReadOnly);
@@ -3306,6 +3301,7 @@ void tst_QVariant::movabilityTest()
 
         memcpy(buffer, &variant, sizeof(QVariant));
         QCOMPARE(buffer[0].type(), QVariant::UserType);
+        QCOMPARE(buffer[0].userType(), qMetaTypeId<MyNotMovable>());
         MyNotMovable tmp(buffer[0].value<MyNotMovable>());
 
         new (&variant) QVariant();
diff --git a/tests/auto/dbus/qdbusmarshall/common.h b/tests/auto/dbus/qdbusmarshall/common.h
index d49f4eff30..87c434b71e 100644
--- a/tests/auto/dbus/qdbusmarshall/common.h
+++ b/tests/auto/dbus/qdbusmarshall/common.h
@@ -610,10 +610,6 @@ template<> bool compare(const QVariant &v1, const QVariant &v2)
     else if (id == QVariant::ByteArray)
         return compare(v1.toByteArray(), v2.toByteArray());
 
-    else if (id < int(QVariant::UserType)) // yes, v1.type()
-        // QVariant can compare
-        return v1 == v2;
-
     else if (id == QMetaType::UChar)
         return qvariant_cast<uchar>(v1) == qvariant_cast<uchar>(v2);
 
@@ -716,6 +712,10 @@ template<> bool compare(const QVariant &v1, const QVariant &v2)
     else if (id == qMetaTypeId<MyStruct>()) // (is)
             return qvariant_cast<MyStruct>(v1) == qvariant_cast<MyStruct>(v2);
 
+    else if (id < int(QVariant::UserType)) // yes, v1.type()
+        // QVariant can compare
+        return v1 == v2;
+
     else {
         qWarning() << "Please write a comparison case for type" << v1.typeName();
         return false;           // unknown type