Long live qxp::is_virtual_base_of

To be used in QWeakPointer.

Change-Id: I5ee9dd0862a0b23d316aaadf5d68bef1ce609e8b
Reviewed-by: Fabian Kosmale <fabian.kosmale@qt.io>
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>

2 files changed, 114 insertions, 0 deletions

diff --git a/tests/auto/corelib/global/qxp/is_virtual_base_of/CMakeLists.txt b/tests/auto/corelib/global/qxp/is_virtual_base_of/CMakeLists.txt
new file mode 100644
index 0000000000..5762a32f48
--- /dev/null
+++ b/tests/auto/corelib/global/qxp/is_virtual_base_of/CMakeLists.txt
@@ -0,0 +1,16 @@
+# Copyright (C) 2022 The Qt Company Ltd.
+# SPDX-License-Identifier: BSD-3-Clause
+
+if(NOT QT_BUILD_STANDALONE_TESTS AND NOT QT_BUILDING_QT)
+    cmake_minimum_required(VERSION 3.16)
+    project(tst_qxp_is_virtual_base_of LANGUAGES CXX)
+    find_package(Qt6BuildInternals REQUIRED COMPONENTS STANDALONE_TEST)
+endif()
+
+qt_internal_add_test(tst_qxp_is_virtual_base_of
+    EXCEPTIONS
+    SOURCES
+        tst_is_virtual_base_of.cpp
+    LIBRARIES
+        Qt::Core
+)
diff --git a/tests/auto/corelib/global/qxp/is_virtual_base_of/tst_is_virtual_base_of.cpp b/tests/auto/corelib/global/qxp/is_virtual_base_of/tst_is_virtual_base_of.cpp
new file mode 100644
index 0000000000..2f022ee3de
--- /dev/null
+++ b/tests/auto/corelib/global/qxp/is_virtual_base_of/tst_is_virtual_base_of.cpp
@@ -0,0 +1,98 @@
+// Copyright (C) 2023 Klarälvdalens Datakonsult AB, a KDAB Group company, info@kdab.com, author Giuseppe D'Angelo <giuseppe.dangelo@kdab.com>
+// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR GPL-3.0-only WITH Qt-GPL-exception-1.0
+
+#include <QtCore/qxptype_traits.h>
+
+#include <QTest>
+
+class tst_qxp_is_virtual_base_of : public QObject
+{
+    Q_OBJECT
+};
+
+class Base {
+public:
+    virtual ~Base() {}
+};
+
+// Only works with classes
+static_assert(!qxp::is_virtual_base_of_v<int, int>);
+static_assert(!qxp::is_virtual_base_of_v<int, Base>);
+static_assert(!qxp::is_virtual_base_of_v<Base, int>);
+
+// A class isn't a virtual base of itself
+static_assert(!qxp::is_virtual_base_of_v<Base, Base>);
+
+// Non-virtual bases
+class NonVirtualDerived : public Base {};
+class NonVirtualPrivateDerived : private Base {};
+
+static_assert(!qxp::is_virtual_base_of_v<Base, NonVirtualDerived>);
+static_assert(!qxp::is_virtual_base_of_v<Base, NonVirtualPrivateDerived>);
+
+static_assert(!qxp::is_virtual_base_of_v<NonVirtualPrivateDerived, NonVirtualDerived>);
+static_assert(!qxp::is_virtual_base_of_v<NonVirtualDerived, NonVirtualPrivateDerived>);
+
+static_assert(!qxp::is_virtual_base_of_v<tst_qxp_is_virtual_base_of, QObject>);
+
+// Virtual bases
+class VirtualDerived1 : public virtual Base {};
+class VirtualDerived2 : public virtual Base {};
+class VirtualDerived3 : public VirtualDerived1, public VirtualDerived2 {};
+class VirtualDerived4 : public VirtualDerived3, public virtual Base {};
+class VirtualPrivateDerived : private virtual Base {};
+
+static_assert(qxp::is_virtual_base_of_v<Base, VirtualDerived1>);
+static_assert(qxp::is_virtual_base_of_v<Base, VirtualDerived2>);
+static_assert(qxp::is_virtual_base_of_v<Base, VirtualDerived3>);
+static_assert(!qxp::is_virtual_base_of_v<VirtualDerived1, VirtualDerived3>);
+static_assert(qxp::is_virtual_base_of_v<Base, VirtualDerived4>);
+static_assert(qxp::is_virtual_base_of_v<Base, VirtualPrivateDerived>);
+
+// Ambiguous non-virtual base
+class IntermediateDerived : public Base {};
+class AmbiguousBase1 : public IntermediateDerived, public Base {};
+class AmbiguousBase2 : public IntermediateDerived, public virtual Base {};
+
+static_assert(!qxp::is_virtual_base_of_v<Base, AmbiguousBase1>);
+#ifndef Q_CC_MSVC_ONLY // https://developercommunity.visualstudio.com/t/c-templates-multiple-inheritance-ambiguous-access/185674
+static_assert(!qxp::is_virtual_base_of_v<Base, AmbiguousBase2>);
+#endif
+
+// Const
+static_assert(!qxp::is_virtual_base_of_v<      Base, const NonVirtualDerived>);
+static_assert(!qxp::is_virtual_base_of_v<const Base,       NonVirtualDerived>);
+static_assert(!qxp::is_virtual_base_of_v<const Base, const NonVirtualDerived>);
+
+static_assert(!qxp::is_virtual_base_of_v<      Base, const NonVirtualPrivateDerived>);
+static_assert(!qxp::is_virtual_base_of_v<const Base,       NonVirtualPrivateDerived>);
+static_assert(!qxp::is_virtual_base_of_v<const Base, const NonVirtualPrivateDerived>);
+
+static_assert(qxp::is_virtual_base_of_v<      Base, const VirtualDerived1>);
+static_assert(qxp::is_virtual_base_of_v<const Base,       VirtualDerived1>);
+static_assert(qxp::is_virtual_base_of_v<const Base, const VirtualDerived1>);
+
+static_assert(qxp::is_virtual_base_of_v<      Base, const VirtualDerived2>);
+static_assert(qxp::is_virtual_base_of_v<const Base,       VirtualDerived2>);
+static_assert(qxp::is_virtual_base_of_v<const Base, const VirtualDerived2>);
+
+static_assert(qxp::is_virtual_base_of_v<      Base, const VirtualDerived3>);
+static_assert(qxp::is_virtual_base_of_v<const Base,       VirtualDerived3>);
+static_assert(qxp::is_virtual_base_of_v<const Base, const VirtualDerived3>);
+
+static_assert(qxp::is_virtual_base_of_v<      Base, const VirtualDerived4>);
+static_assert(qxp::is_virtual_base_of_v<const Base,       VirtualDerived4>);
+static_assert(qxp::is_virtual_base_of_v<const Base, const VirtualDerived4>);
+
+static_assert(qxp::is_virtual_base_of_v<      Base, const VirtualDerived4>);
+static_assert(qxp::is_virtual_base_of_v<const Base,       VirtualDerived4>);
+static_assert(qxp::is_virtual_base_of_v<const Base, const VirtualDerived4>);
+
+static_assert(qxp::is_virtual_base_of_v<      Base, const VirtualPrivateDerived>);
+static_assert(qxp::is_virtual_base_of_v<const Base,       VirtualPrivateDerived>);
+static_assert(qxp::is_virtual_base_of_v<const Base, const VirtualPrivateDerived>);
+
+
+QTEST_APPLESS_MAIN(tst_qxp_is_virtual_base_of);
+
+#include "tst_is_virtual_base_of.moc"