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Short live pointer_cast!
A collection of helper functions to ease porting from `QSharedPointer` to `std::shared_ptr`, by helping with the most egregious API incompatibilites of QSharedPointer, to wit: - static_pointer_cast overload for QSharedPointer - dynamic_pointer_cast overload for QSharedPointer - const_pointer_cast overload for QSharedPointer - make_qshared - like std::make_shared, but returning QSharedPointer The casts are designed to be used like their `std` counterparts operating on `std::shared_ptr`. We advise to used unqualified lookup QSharedPointer<Base> base = make_qshared<Derived>(~~~); auto derived = dynamic_pointer_cast<Derived>(base); // not KDToolBox::... If you target C++20, then this is also the way to call `std::dynamic_pointer_cast` (unqualifed lookup of functions with explicit template arguments doesn't find candidates by ADL prior to C++20) For this reason, the functions are defined in `inline namespace KDToolBox`. If you restict your code to the std-compatible subset of QSharedPointer and use te above four functions, then porting from QSharedPointer to std::shared_ptr will be as easy as s/QSharedPointer/std::shared_ptr/ s/QWeakPointer/std::weak_ptr/ s/make_qshared/std::make_shared/ Enjoy! Change-Id: I4265c8568e61196d5494f98798515f101e8d4e67 Reviewed-on: https://codereview.kdab.com/c/kdab/KDToolBox/+/97789 Tested-by: Continuous Integration <[email protected]> Reviewed-by: Milian Wolff <[email protected]> Reviewed-by: Giuseppe D'Angelo <[email protected]>
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‎README.md

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Intercept `Q_ASSERT` failures with ASAN and print a backtrace.
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- [KDSqlDatabaseTransaction](https://github.com/KDAB/KDToolBox/tree/master/qt/KDSqlDatabaseTransaction)
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A RAII wrapper for database transactions when using the Qt SQL APIs.
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- [pointer_cast](https://github.com/KDAB/KDToolBox/tree/master/qt/pointer_cast)
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Tools to ease migrating from `QSharedPointer` to `std::shared_ptr`.
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Other code snippets
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===================

‎qt/pointer_cast/README.md

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pointer-cast
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==================
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A collection of helper functions to ease porting from `QSharedPointer`
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to `std::shared_ptr`, by helping with the most egregious API
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incompatibilites of QSharedPointer, to wit:
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- static_pointer_cast overload for QSharedPointer
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- dynamic_pointer_cast overload for QSharedPointer
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- const_pointer_cast overload for QSharedPointer
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- make_qshared - like std::make_shared, but returning QSharedPointer
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The casts are designed to be used like their `std` counterparts
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operating on `std::shared_ptr`. We advise to used unqualified lookup
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QSharedPointer<Base> base = make_qshared<Derived>(~~~);
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auto derived = dynamic_pointer_cast<Derived>(base); // not KDToolBox::...
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If you target C++20, then this is also the way to call
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`std::dynamic_pointer_cast` (unqualifed lookup of functions with
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explicit template arguments doesn't find candidates by ADL prior to
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C++20) For this reason, the functions are defined in `inline namespace
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KDToolBox`.
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If you restict your code to the std-compatible subset of
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QSharedPointer and use te above four functions, then porting from
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QSharedPointer to std::shared_ptr will be as easy as
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s/QSharedPointer/std::shared_ptr/
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s/QWeakPointer/std::weak_ptr/
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s/make_qshared/std::make_shared/
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Enjoy!

‎qt/pointer_cast/pointer_cast.h

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/****************************************************************************
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** MIT License
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**
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** Copyright (C) 2020-2021 Klarälvdalens Datakonsult AB, a KDAB Group company, [email protected]
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** Author: Giuseppe D'Angelo <[email protected]>
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**
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** This file is part of KDToolBox (https://github.com/KDAB/KDToolBox).
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**
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** Permission is hereby granted, free of charge, to any person obtaining a copy
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** of this software and associated documentation files (the "Software"), to deal
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** in the Software without restriction, including without limitation the rights
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** to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
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** copies of the Software, ** and to permit persons to whom the Software is
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** furnished to do so, subject to the following conditions:
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**
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** The above copyright notice and this permission notice (including the next paragraph)
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** shall be included in all copies or substantial portions of the Software.
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**
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** THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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** IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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** FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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** AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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** LIABILITY, WHETHER IN AN ACTION OF ** CONTRACT, TORT OR OTHERWISE,
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** ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
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** DEALINGS IN THE SOFTWARE.
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****************************************************************************/
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#pragma once
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#include <QSharedPointer>
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#include <utility>
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inline namespace KDToolBox {
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template <typename To, typename From>
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QSharedPointer<To> static_pointer_cast(const QSharedPointer<From>& from)
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{
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return from.template staticCast<To>();
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}
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template <typename To, typename From>
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QSharedPointer<To> dynamic_pointer_cast(const QSharedPointer<From>& from)
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{
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return from.template dynamicCast<To>();
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}
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template <typename To, typename From>
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QSharedPointer<To> const_pointer_cast(const QSharedPointer<From>& from)
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{
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return from.template constCast<To>();
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}
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template <typename T, typename...Args>
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QSharedPointer<T> make_qshared(Args&&...args)
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{
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return QSharedPointer<T>::create(std::forward<Args>(args)...);
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}
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} // namespace KDToolBox

‎qt/pointer_cast/pointer_cast.pro

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TEMPLATE = subdirs
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HEADERS += \
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pointer_cast.h \
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SUBDIRS += \
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test \

‎qt/pointer_cast/test/test.pro

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TEMPLATE = app
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TARGET = tst_pointer_cast
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QT = core testlib
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CONFIG += testcase c++14
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SOURCES += \
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tst_pointer_cast.cpp \
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‎qt/pointer_cast/test/tst_pointer_cast.cpp

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/****************************************************************************
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** MIT License
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**
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** Copyright (C) 2019-2021 Klarälvdalens Datakonsult AB, a KDAB Group company, [email protected]
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**
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** This file is part of KDToolBox (https://github.com/KDAB/KDToolBox).
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**
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** Permission is hereby granted, free of charge, to any person obtaining a copy
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** of this software and associated documentation files (the "Software"), to deal
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** in the Software without restriction, including without limitation the rights
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** to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
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** copies of the Software, ** and to permit persons to whom the Software is
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** furnished to do so, subject to the following conditions:
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**
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** The above copyright notice and this permission notice (including the next paragraph)
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** shall be included in all copies or substantial portions of the Software.
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**
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** THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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** IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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** FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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** AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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** LIABILITY, WHETHER IN AN ACTION OF ** CONTRACT, TORT OR OTHERWISE,
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** ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
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** DEALINGS IN THE SOFTWARE.
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****************************************************************************/
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#include <QTest>
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#include "../pointer_cast.h"
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class tst_pointer_cast : public QObject
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{
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Q_OBJECT
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private Q_SLOTS:
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void makeQShared();
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void staticCast();
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void dynamicCast();
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void constCast();
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};
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namespace {
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struct B {
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virtual ~B() = default;
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};
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struct D : B {};
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struct D2 : B {};
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} // unnamed namespace
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void tst_pointer_cast::makeQShared()
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{
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{
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auto p = make_qshared<int>(42);
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Q_STATIC_ASSERT((std::is_same<decltype(p), QSharedPointer<int>>::value));
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QVERIFY(p);
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QCOMPARE(*p, 42);
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}
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{
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auto p = make_qshared<QString>("Hello");
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Q_STATIC_ASSERT((std::is_same<decltype(p), QSharedPointer<QString>>::value));
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QVERIFY(p);
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QCOMPARE(*p, "Hello");
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}
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}
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void tst_pointer_cast::staticCast()
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{
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auto b = make_qshared<D>();
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QVERIFY(b);
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auto d = static_pointer_cast<D>(b);
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QCOMPARE(b, d);
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}
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void tst_pointer_cast::dynamicCast()
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{
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auto b = make_qshared<D>();
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QVERIFY(b);
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auto d = dynamic_pointer_cast<D>(b);
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QCOMPARE(b, d);
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auto d2 = dynamic_pointer_cast<D2>(b);
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QCOMPARE(d2, nullptr);
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}
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void tst_pointer_cast::constCast()
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{
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auto cd = make_qshared<const D>();
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QVERIFY(cd);
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auto md = const_pointer_cast<D>(cd);
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QCOMPARE(md, cd);
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}
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QTEST_MAIN(tst_pointer_cast)
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#include "tst_pointer_cast.moc"

‎qt/qt.pro

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messagehandler \
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model_view \
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notify_guard \
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pointer_cast \
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qml \
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qt_hasher \
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singleshot_connect \

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