From fee8944cbe2a976e1b4a71c5df048e84a0bc6db0 Mon Sep 17 00:00:00 2001 From: Nils Jeisecke Date: Fri, 2 Mar 2018 16:57:11 +0100 Subject: [PATCH] Allow use of template class instances inheriting from a Q_GADGET in Qml The Q_GADGET macro cannot be used in templates. It can however be useful to derive a template class from a Q_GADGET enabled base class to benefit from type safety features in C++ (e.g. the class could represent an id or handle for some C++ type). For proper wrapping of a QVariant with a gadget value in a QJSValue, the QMetaType::IsGadget flag must be set for the registered template instance type - which does not happen prior to the fix because IsGadgetHelper requires qt_check_for_QGADGET_macro to be defined in the registered class but not in an ancestor class - in other words: The class must declare Q_GADGET. To overcome this, IsGadgetHelper/IsPointerToGadgetHelper can now differentiate between a Q_GADGET flagged class (allowing automatic registration) and a derived class, e.g. a template class (forcing Q_DECLARE_METATYPE to be used explicitly). [ChangeLog][QtCore][QMetaObject] It is now possible to use template class instances inheriting from a Q_GADGET in Qml Task-number: QTBUG-66744 Change-Id: I7632ad45cff79fa422b3f852ca0b963f35fab155 Reviewed-by: Olivier Goffart (Woboq GmbH) --- src/corelib/kernel/qmetatype.h | 26 ++++++++++++------- .../kernel/qmetatype/tst_qmetatype.cpp | 19 ++++++++++++++ 2 files changed, 35 insertions(+), 10 deletions(-) diff --git a/src/corelib/kernel/qmetatype.h b/src/corelib/kernel/qmetatype.h index 455d0350e01..4674efe5680 100644 --- a/src/corelib/kernel/qmetatype.h +++ b/src/corelib/kernel/qmetatype.h @@ -1381,7 +1381,7 @@ namespace QtPrivate }; template - struct IsGadgetHelper { enum { Value = false }; }; + struct IsGadgetHelper { enum { IsRealGadget = false, IsGadgetOrDerivedFrom = false }; }; template struct IsGadgetHelper @@ -1389,11 +1389,14 @@ namespace QtPrivate template static char checkType(void (X::*)()); static void *checkType(void (T::*)()); - enum { Value = sizeof(checkType(&T::qt_check_for_QGADGET_macro)) == sizeof(void *) }; + enum { + IsRealGadget = sizeof(checkType(&T::qt_check_for_QGADGET_macro)) == sizeof(void *), + IsGadgetOrDerivedFrom = true + }; }; template - struct IsPointerToGadgetHelper { enum { Value = false }; }; + struct IsPointerToGadgetHelper { enum { IsRealGadget = false, IsGadgetOrDerivedFrom = false }; }; template struct IsPointerToGadgetHelper @@ -1402,7 +1405,10 @@ namespace QtPrivate template static char checkType(void (X::*)()); static void *checkType(void (T::*)()); - enum { Value = sizeof(checkType(&T::qt_check_for_QGADGET_macro)) == sizeof(void *) }; + enum { + IsRealGadget = sizeof(checkType(&T::qt_check_for_QGADGET_macro)) == sizeof(void *), + IsGadgetOrDerivedFrom = true + }; }; @@ -1435,12 +1441,12 @@ namespace QtPrivate static inline const QMetaObject *value() { return &T::staticMetaObject; } }; template - struct MetaObjectForType::Value>::type> + struct MetaObjectForType::IsGadgetOrDerivedFrom>::type> { static inline const QMetaObject *value() { return &T::staticMetaObject; } }; template - struct MetaObjectForType::Value>::Type> + struct MetaObjectForType::IsGadgetOrDerivedFrom>::type> { static inline const QMetaObject *value() { return &IsPointerToGadgetHelper::BaseType::staticMetaObject; } }; @@ -1599,8 +1605,8 @@ namespace QtPrivate template ::Value ? QMetaType::PointerToQObject : - QtPrivate::IsGadgetHelper::Value ? QMetaType::IsGadget : - QtPrivate::IsPointerToGadgetHelper::Value ? QMetaType::PointerToGadget : + QtPrivate::IsGadgetHelper::IsRealGadget ? QMetaType::IsGadget : + QtPrivate::IsPointerToGadgetHelper::IsRealGadget ? QMetaType::PointerToGadget : QtPrivate::IsQEnumHelper::Value ? QMetaType::IsEnumeration : 0> struct QMetaTypeIdQObject { @@ -1653,8 +1659,8 @@ namespace QtPrivate { | (IsWeakPointerToTypeDerivedFromQObject::Value ? QMetaType::WeakPointerToQObject : 0) | (IsTrackingPointerToTypeDerivedFromQObject::Value ? QMetaType::TrackingPointerToQObject : 0) | (std::is_enum::value ? QMetaType::IsEnumeration : 0) - | (IsGadgetHelper::Value ? QMetaType::IsGadget : 0) - | (IsPointerToGadgetHelper::Value ? QMetaType::PointerToGadget : 0) + | (IsGadgetHelper::IsGadgetOrDerivedFrom ? QMetaType::IsGadget : 0) + | (IsPointerToGadgetHelper::IsGadgetOrDerivedFrom ? QMetaType::PointerToGadget : 0) }; }; diff --git a/tests/auto/corelib/kernel/qmetatype/tst_qmetatype.cpp b/tests/auto/corelib/kernel/qmetatype/tst_qmetatype.cpp index cc628ee26e3..c6fd5d17c2d 100644 --- a/tests/auto/corelib/kernel/qmetatype/tst_qmetatype.cpp +++ b/tests/auto/corelib/kernel/qmetatype/tst_qmetatype.cpp @@ -141,6 +141,14 @@ public: class CustomNonQObject {}; class GadgetDerived : public CustomGadget {}; +// cannot use Q_GADGET due to moc limitations but wants to behave like +// a Q_GADGET in Qml land +template +class GadgetDerivedAndTyped : public CustomGadget {}; + +Q_DECLARE_METATYPE(GadgetDerivedAndTyped) +Q_DECLARE_METATYPE(GadgetDerivedAndTyped*) + void tst_QMetaType::defined() { QCOMPARE(int(QMetaTypeId2::Defined), 1); @@ -157,6 +165,10 @@ void tst_QMetaType::defined() QVERIFY(!QMetaTypeId2::Defined); QVERIFY(!QMetaTypeId2::Defined); QVERIFY(!QMetaTypeId2::Defined); + + // registered with Q_DECLARE_METATYPE + QVERIFY(QMetaTypeId2>::Defined); + QVERIFY(QMetaTypeId2*>::Defined); } struct Bar @@ -396,6 +408,10 @@ void tst_QMetaType::typeName_data() QTest::newRow("CustomGadget*") << ::qMetaTypeId() << QString::fromLatin1("CustomGadget*"); QTest::newRow("CustomQObject::CustomQEnum") << ::qMetaTypeId() << QString::fromLatin1("CustomQObject::CustomQEnum"); QTest::newRow("Qt::ArrowType") << ::qMetaTypeId() << QString::fromLatin1("Qt::ArrowType"); + + // template instance class derived from Q_GADGET enabled class + QTest::newRow("GadgetDerivedAndTyped") << ::qMetaTypeId>() << QString::fromLatin1("GadgetDerivedAndTyped"); + QTest::newRow("GadgetDerivedAndTyped*") << ::qMetaTypeId*>() << QString::fromLatin1("GadgetDerivedAndTyped*"); } void tst_QMetaType::typeName() @@ -1703,6 +1719,9 @@ void tst_QMetaType::metaObject_data() QTest::newRow("MyGadget*") << ::qMetaTypeId() << &MyGadget::staticMetaObject << false << true << false; QTest::newRow("MyEnum") << ::qMetaTypeId() << &MyGadget::staticMetaObject << false << false << false; QTest::newRow("Qt::ScrollBarPolicy") << ::qMetaTypeId() << &QObject::staticQtMetaObject << false << false << false; + + QTest::newRow("GadgetDerivedAndTyped") << ::qMetaTypeId>() << &GadgetDerivedAndTyped::staticMetaObject << true << false << false; + QTest::newRow("GadgetDerivedAndTyped*") << ::qMetaTypeId*>() << &GadgetDerivedAndTyped::staticMetaObject << false << true << false; }