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QVariant: Fix conversion code

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Fixes: QTBUG-86330
Change-Id: Ib89dcf1195e0081b4c4e2845f90c52c612e5911a
Reviewed-by: Ulf Hermann <ulf.hermann@qt.io>
This commit is contained in:
Fabian Kosmale 2020-08-31 16:42:36 +02:00
parent 3ddffd2d8b
commit 19874d6a63
2 changed files with 49 additions and 2 deletions
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13
src/corelib/kernel/qmetatype.cpp
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@ -2050,8 +2050,17 @@ bool QMetaType::convert(QMetaType fromType, const void *from, QMetaType toType,
// handle QObject conversion
if ((fromType.flags() & QMetaType::PointerToQObject) && (toType.flags() & QMetaType::PointerToQObject)) {
QObject *fromObject = *static_cast<QObject * const *>(from);
*static_cast<QObject **>(to) = fromObject ? fromObject->metaObject()->cast(fromObject) : nullptr;
return true;
// use dynamic metatype of from if possible
if (fromObject && fromObject->metaObject()->inherits(toType.metaObject())) {
*static_cast<QObject **>(to) = toType.metaObject()->cast(fromObject);
return true;
} else if (!fromObject) {
// if fromObject is null, use static fromType to check if conversion works
*static_cast<void **>(to) = nullptr;
return fromType.metaObject()->inherits(toType.metaObject());
} else {
return false;
}
}
#endif

38
tests/auto/corelib/kernel/qvariant/tst_qvariant.cpp
View File

@ -221,6 +221,7 @@ private slots:
void compareCustomTypes() const;
void timeToDateTime() const;
void copyingUserTypes() const;
void valueClassHierarchyConversion() const;
void convertBoolToByteArray() const;
void convertBoolToByteArray_data() const;
void convertByteArrayToBool() const;
@ -2894,6 +2895,43 @@ void tst_QVariant::copyingUserTypes() const
QCOMPARE(copiedType.myValue, 42);
}
struct NonQObjectBase {};
struct NonQObjectDerived : NonQObjectBase {};
void tst_QVariant::valueClassHierarchyConversion() const
{
{
// QVariant allows downcasting
QScopedPointer<CustomQObjectDerived> derived {new CustomQObjectDerived};
QVariant var = QVariant::fromValue(derived.get());
CustomQObject *object = var.value<CustomQObject *>();
QVERIFY(object);
}
{
// QVariant supports upcasting to the correct dynamic type for QObjects
QScopedPointer<CustomQObjectDerived> derived {new CustomQObjectDerived};
QVariant var = QVariant::fromValue<CustomQObject *>(derived.get());
CustomQObjectDerived *object = var.value<CustomQObjectDerived *>();
QVERIFY(object);
}
{
// QVariant forbids unsafe upcasting
QScopedPointer<CustomQObject> base {new CustomQObject};
QVariant var = QVariant::fromValue(base.get());
CustomQObjectDerived *object = var.value<CustomQObjectDerived *>();
QVERIFY(!object);
}
{
// QVariant does not support upcastingfor non-QObjects
QScopedPointer<NonQObjectDerived> derived {new NonQObjectDerived};
QVariant var = QVariant::fromValue<NonQObjectBase *>(derived.get());
NonQObjectDerived *object = var.value<NonQObjectDerived *>();
QVERIFY(!object);
}
}
void tst_QVariant::convertBoolToByteArray() const
{
QFETCH(QByteArray, input);