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Allow getting a const pointer out of a variant containing pointer

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Currently
  A a;
  QVariant::fromValue(&a).value<const A*>() == nullptr;
Still casting non const to const is safe, and worked in Qt5.
After this change
  A a;
  QVariant::fromValue(&a).value<const A*>() == &a;

Change-Id: I257049d084c712b00a338a2943d379aa478e0981
Reviewed-by: Fabian Kosmale <fabian.kosmale@qt.io>
This commit is contained in:
Fawzi Mohamed 2020-09-11 15:08:26 +02:00
parent 6c7ed4c013
commit f69144471b
2 changed files with 19 additions and 0 deletions
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7
src/corelib/kernel/qvariant.h
View File

@ -53,6 +53,7 @@
#include <QtCore/qbytearraylist.h>
#endif
#include <memory>
#include <type_traits>
#if __has_include(<variant>) && __cplusplus >= 201703L
#include <variant>
@ -572,6 +573,12 @@ template<typename T> inline T qvariant_cast(const QVariant &v)
QMetaType targetType = QMetaType::fromType<T>();
if (v.d.type() == targetType)
return v.d.get<T>();
if constexpr (std::is_same_v<T,std::remove_const_t<std::remove_pointer_t<T>> const *>) {
using nonConstT = std::remove_const_t<std::remove_pointer_t<T>> *;
QMetaType nonConstTargetType = QMetaType::fromType<nonConstT>();
if (v.d.type() == nonConstTargetType)
return v.d.get<nonConstT>();
}
T t{};
QMetaType::convert(v.metaType(), v.constData(), targetType, &t);

12
tests/auto/corelib/kernel/qvariant/tst_qvariant.cpp
View File

@ -169,6 +169,7 @@ private slots:
void qvariant_cast_QObject_derived();
void qvariant_cast_QObject_wrapper();
void qvariant_cast_QSharedPointerQObject();
void qvariant_cast_const();
void toLocale();
@ -2579,6 +2580,17 @@ void tst_QVariant::qvariant_cast_QSharedPointerQObject()
qRegisterMetaType<QSharedPointer<QObject> >();
}
void tst_QVariant::qvariant_cast_const()
{
int i = 42;
QVariant v = QVariant::fromValue(&i);
QVariant vConst = QVariant::fromValue(const_cast<const int*>(&i));
QCOMPARE(v.value<int *>(), &i);
QCOMPARE(v.value<const int *>(), &i);
QCOMPARE(vConst.value<int *>(), nullptr);
QCOMPARE(vConst.value<const int *>(), &i);
}
void tst_QVariant::convertToQUint8() const
{
/* qint8. */