common: Disable enum type stream operators for Qt >= 5.14

Starting from version 5.14, Qt provides stream operators for enum
types, which collide with the ones we ship in types.h. Disable
Quassel's stream operators when compiling against Qt 5.14 or later.

Add a unit test that ensures that enum serialization honors the width
of the underlying type.

src/common/types.h

@@ -195,6 +195,7 @@ Q_DECLARE_METATYPE(QHostAddress)
 using MsgIdList = QList<MsgId>;
 using BufferIdList = QList<BufferId>;
 
+#if QT_VERSION < QT_VERSION_CHECK(5, 14, 0)
 /**
  * Catch-all stream serialization operator for enum types.
  *
@@ -224,6 +225,7 @@ QDataStream& operator>>(QDataStream& in, T& value)
     value = static_cast<T>(v);
     return in;
 }
+#endif
 
 // STL-compliant hash functor for Qt types
 template<typename T>

tests/common/CMakeLists.txt

@@ -11,4 +11,6 @@ quassel_add_test(SignalProxyTest
         Quassel::Test::Util
 )
 
+quassel_add_test(TypesTest)
+
 quassel_add_test(UtilTest)

tests/common/typestest.cpp

@@ -0,0 +1,79 @@
+/***************************************************************************
+ *   Copyright (C) 2005-2020 by the Quassel Project                        *
+ *   devel@quassel-irc.org                                                 *
+ *                                                                         *
+ *   This program is free software; you can redistribute it and/or modify  *
+ *   it under the terms of the GNU General Public License as published by  *
+ *   the Free Software Foundation; either version 2 of the License, or     *
+ *   (at your option) version 3.                                           *
+ *                                                                         *
+ *   This program is distributed in the hope that it will be useful,       *
+ *   but WITHOUT ANY WARRANTY; without even the implied warranty of        *
+ *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the         *
+ *   GNU General Public License for more details.                          *
+ *                                                                         *
+ *   You should have received a copy of the GNU General Public License     *
+ *   along with this program; if not, write to the                         *
+ *   Free Software Foundation, Inc.,                                       *
+ *   51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.         *
+ ***************************************************************************/
+
+#include <cstdint>
+
+#include <QByteArray>
+#include <QDataStream>
+#include <QObject>
+
+#include "testglobal.h"
+#include "types.h"
+
+using namespace ::testing;
+
+class EnumHolder
+{
+    Q_GADGET
+
+public:
+    enum class Enum16 : uint16_t {};
+    enum class Enum32 : uint32_t {};
+
+    enum class EnumQt16 : uint16_t {};
+    Q_ENUM(EnumQt16)
+    enum class EnumQt32 : uint32_t {};
+    Q_ENUM(EnumQt32)
+};
+
+// Verify that enums are (de)serialized as their underlying type
+TEST(TypesTest, enumSerialization)
+{
+    QByteArray data;
+    QDataStream out(&data, QIODevice::WriteOnly);
+
+    // Serialize
+    out << EnumHolder::Enum16(0xabcd);
+    ASSERT_THAT(data.size(), Eq(2));
+    out << EnumHolder::Enum32(0x123456);
+    ASSERT_THAT(data.size(), Eq(6));
+    out << EnumHolder::EnumQt16(0x4321);
+    ASSERT_THAT(data.size(), Eq(8));
+    out << EnumHolder::Enum32(0xfedcba);
+    ASSERT_THAT(data.size(), Eq(12));
+    ASSERT_THAT(out.status(), Eq(QDataStream::Status::Ok));
+
+    // Deserialize
+    QDataStream in(data);
+    EnumHolder::Enum16 enum16;
+    EnumHolder::Enum32 enum32;
+    EnumHolder::EnumQt16 enumQt16;
+    EnumHolder::EnumQt32 enumQt32;
+    in >> enum16  >> enum32 >> enumQt16 >> enumQt32;
+    ASSERT_THAT(in.status(), Eq(QDataStream::Status::Ok));
+    EXPECT_TRUE(in.atEnd());
+
+    EXPECT_THAT((int)enum16, Eq(0xabcd));
+    EXPECT_THAT((int)enum32, Eq(0x123456));
+    EXPECT_THAT((int)enumQt16, Eq(0x4321));
+    EXPECT_THAT((int)enumQt32, Eq(0xfedcba));
+}
+
+#include "typestest.moc"