QMetaMethod::typeName() should return "void" if the return type is void

QMetaMethod::typeName() is documented to return an empty string if
the return type is void. But after the introduction of
QMetaType::UnknownType (where void was made a distinct type),
returning an empty string causes the idiom

   QMetaType::type(method.typeName())

to break; the result will be QMetaType::UnknownType rather than
the expected QMetaType::Void for methods that return void.

New code should use the new function QMetaMethod::returnType()
instead, but it would be good if existing code still did the right
thing.

The consequence of returning "void" instead of an empty string is
that it breaks existing logic that uses the typeName() length to
determine whether a method returns void. But we judge this as the
lesser of the two evils; it's better to have a typeName() function
that is consistent and keeps the QMetaType::type(method.typeName())
idiom working, than to force the typeName() inconsistency for void
only to keep code that does "strlen(method.typeName()) == 0"
working.

The places in Qt that were relying on a zero-length typeName()
(testlib, dbus, declarative) have already been changed to use
returnType().

Also adapt QMetaObjectBuilder, which is internal API.

Change-Id: I70249174029811c5b5d2a08c24b6db33b3723d19
Reviewed-by: Jędrzej Nowacki <jedrzej.nowacki@nokia.com>
Reviewed-by: Olivier Goffart <ogoffart@woboq.com>
Reviewed-by: Lars Knoll <lars.knoll@nokia.com>

2 files changed, 28 insertions, 27 deletions

diff --git a/tests/auto/corelib/kernel/qmetamethod/tst_qmetamethod.cpp b/tests/auto/corelib/kernel/qmetamethod/tst_qmetamethod.cpp
index 0285dd0216..55997a3ca0 100644
--- a/tests/auto/corelib/kernel/qmetamethod/tst_qmetamethod.cpp
+++ b/tests/auto/corelib/kernel/qmetamethod/tst_qmetamethod.cpp
@@ -197,7 +197,7 @@ void tst_QMetaMethod::method_data()
 
     QTest::newRow("voidSignal")
             << QByteArray("voidSignal()")
-            << int(QMetaType::Void) << QByteArray("")
+            << int(QMetaType::Void) << QByteArray("void")
             << (QList<int>())
             << (QList<QByteArray>())
             << (QList<QByteArray>())
@@ -206,7 +206,7 @@ void tst_QMetaMethod::method_data()
 
     QTest::newRow("voidInvokable")
             << QByteArray("voidInvokable()")
-            << int(QMetaType::Void) << QByteArray("")
+            << int(QMetaType::Void) << QByteArray("void")
             << (QList<int>())
             << (QList<QByteArray>())
             << (QList<QByteArray>())
@@ -215,7 +215,7 @@ void tst_QMetaMethod::method_data()
 
     QTest::newRow("voidSlot")
             << QByteArray("voidSlot()")
-            << int(QMetaType::Void) << QByteArray("")
+            << int(QMetaType::Void) << QByteArray("void")
             << (QList<int>())
             << (QList<QByteArray>())
             << (QList<QByteArray>())
@@ -233,7 +233,7 @@ void tst_QMetaMethod::method_data()
 
     QTest::newRow("voidSignalVoid")
             << QByteArray("voidSignalVoid()")
-            << int(QMetaType::Void) << QByteArray("")
+            << int(QMetaType::Void) << QByteArray("void")
             << QList<int>()
             << QList<QByteArray>()
             << QList<QByteArray>()
@@ -242,7 +242,7 @@ void tst_QMetaMethod::method_data()
 
     QTest::newRow("voidSignalInt")
             << QByteArray("voidSignalInt(int)")
-            << int(QMetaType::Void) << QByteArray("")
+            << int(QMetaType::Void) << QByteArray("void")
             << (QList<int>() << int(QMetaType::Int))
             << (QList<QByteArray>() << QByteArray("int"))
             << (QList<QByteArray>() << QByteArray("voidSignalIntArg"))
@@ -251,7 +251,7 @@ void tst_QMetaMethod::method_data()
 
     QTest::newRow("voidInvokableInt")
             << QByteArray("voidInvokableInt(int)")
-            << int(QMetaType::Void) << QByteArray("")
+            << int(QMetaType::Void) << QByteArray("void")
             << (QList<int>() << int(QMetaType::Int))
             << (QList<QByteArray>() << QByteArray("int"))
             << (QList<QByteArray>() << QByteArray("voidInvokableIntArg"))
@@ -260,7 +260,7 @@ void tst_QMetaMethod::method_data()
 
     QTest::newRow("voidSlotInt")
             << QByteArray("voidSlotInt(int)")
-            << int(QMetaType::Void) << QByteArray("")
+            << int(QMetaType::Void) << QByteArray("void")
             << (QList<int>() << int(QMetaType::Int))
             << (QList<QByteArray>() << QByteArray("int"))
             << (QList<QByteArray>() << QByteArray("voidSlotIntArg"))
@@ -278,7 +278,7 @@ void tst_QMetaMethod::method_data()
 
     QTest::newRow("voidSignalQReal")
             << QByteArray("voidSignalQReal(qreal)")
-            << int(QMetaType::Void) << QByteArray("")
+            << int(QMetaType::Void) << QByteArray("void")
             << (QList<int>() << qMetaTypeId<qreal>())
             << (QList<QByteArray>() << QByteArray("qreal"))
             << (QList<QByteArray>() << QByteArray("voidSignalQRealArg"))
@@ -287,7 +287,7 @@ void tst_QMetaMethod::method_data()
 
     QTest::newRow("voidInvokableQReal")
             << QByteArray("voidInvokableQReal(qreal)")
-            << int(QMetaType::Void) << QByteArray("")
+            << int(QMetaType::Void) << QByteArray("void")
             << (QList<int>() << qMetaTypeId<qreal>())
             << (QList<QByteArray>() << QByteArray("qreal"))
             << (QList<QByteArray>() << QByteArray("voidInvokableQRealArg"))
@@ -296,7 +296,7 @@ void tst_QMetaMethod::method_data()
 
     QTest::newRow("voidSlotQReal")
             << QByteArray("voidSlotQReal(qreal)")
-            << int(QMetaType::Void) << QByteArray("")
+            << int(QMetaType::Void) << QByteArray("void")
             << (QList<int>() << qMetaTypeId<qreal>())
             << (QList<QByteArray>() << QByteArray("qreal"))
             << (QList<QByteArray>() << QByteArray("voidSlotQRealArg"))
@@ -314,7 +314,7 @@ void tst_QMetaMethod::method_data()
 
     QTest::newRow("voidSignalQString")
             << QByteArray("voidSignalQString(QString)")
-            << int(QMetaType::Void) << QByteArray("")
+            << int(QMetaType::Void) << QByteArray("void")
             << (QList<int>() << int(QMetaType::QString))
             << (QList<QByteArray>() << QByteArray("QString"))
             << (QList<QByteArray>() << QByteArray("voidSignalQStringArg"))
@@ -323,7 +323,7 @@ void tst_QMetaMethod::method_data()
 
     QTest::newRow("voidInvokableQString")
             << QByteArray("voidInvokableQString(QString)")
-            << int(QMetaType::Void) << QByteArray("")
+            << int(QMetaType::Void) << QByteArray("void")
             << (QList<int>() << int(QMetaType::QString))
             << (QList<QByteArray>() << QByteArray("QString"))
             << (QList<QByteArray>() << QByteArray("voidInvokableQStringArg"))
@@ -332,7 +332,7 @@ void tst_QMetaMethod::method_data()
 
     QTest::newRow("voidSlotQString")
             << QByteArray("voidSlotQString(QString)")
-            << int(QMetaType::Void) << QByteArray("")
+            << int(QMetaType::Void) << QByteArray("void")
             << (QList<int>() << int(QMetaType::QString))
             << (QList<QByteArray>() << QByteArray("QString"))
             << (QList<QByteArray>() << QByteArray("voidSlotQStringArg"))
@@ -350,7 +350,7 @@ void tst_QMetaMethod::method_data()
 
     QTest::newRow("voidSignalCustomType")
             << QByteArray("voidSignalCustomType(CustomType)")
-            << int(QMetaType::Void) << QByteArray("")
+            << int(QMetaType::Void) << QByteArray("void")
             << (QList<int>() << qMetaTypeId<CustomType>())
             << (QList<QByteArray>() << QByteArray("CustomType"))
             << (QList<QByteArray>() << QByteArray("voidSignalCustomTypeArg"))
@@ -359,7 +359,7 @@ void tst_QMetaMethod::method_data()
 
     QTest::newRow("voidInvokableCustomType")
             << QByteArray("voidInvokableCustomType(CustomType)")
-            << int(QMetaType::Void) << QByteArray("")
+            << int(QMetaType::Void) << QByteArray("void")
             << (QList<int>() << qMetaTypeId<CustomType>())
             << (QList<QByteArray>() << QByteArray("CustomType"))
             << (QList<QByteArray>() << QByteArray("voidInvokableCustomTypeArg"))
@@ -368,7 +368,7 @@ void tst_QMetaMethod::method_data()
 
     QTest::newRow("voidSlotCustomType")
             << QByteArray("voidSlotCustomType(CustomType)")
-            << int(QMetaType::Void) << QByteArray("")
+            << int(QMetaType::Void) << QByteArray("void")
             << (QList<int>() << qMetaTypeId<CustomType>())
             << (QList<QByteArray>() << QByteArray("CustomType"))
             << (QList<QByteArray>() << QByteArray("voidSlotCustomTypeArg"))
@@ -386,7 +386,7 @@ void tst_QMetaMethod::method_data()
 
     QTest::newRow("voidSignalCustomUnregisteredType")
             << QByteArray("voidSignalCustomUnregisteredType(CustomUnregisteredType)")
-            << int(QMetaType::Void) << QByteArray("")
+            << int(QMetaType::Void) << QByteArray("void")
             << (QList<int>() << 0)
             << (QList<QByteArray>() << QByteArray("CustomUnregisteredType"))
             << (QList<QByteArray>() << QByteArray("voidSignalCustomUnregisteredTypeArg"))
@@ -395,7 +395,7 @@ void tst_QMetaMethod::method_data()
 
     QTest::newRow("voidInvokableCustomUnregisteredType")
             << QByteArray("voidInvokableCustomUnregisteredType(CustomUnregisteredType)")
-            << int(QMetaType::Void) << QByteArray("")
+            << int(QMetaType::Void) << QByteArray("void")
             << (QList<int>() << 0)
             << (QList<QByteArray>() << QByteArray("CustomUnregisteredType"))
             << (QList<QByteArray>() << QByteArray("voidInvokableCustomUnregisteredTypeArg"))
@@ -404,7 +404,7 @@ void tst_QMetaMethod::method_data()
 
     QTest::newRow("voidSlotCustomUnregisteredType")
             << QByteArray("voidSlotCustomUnregisteredType(CustomUnregisteredType)")
-            << int(QMetaType::Void) << QByteArray("")
+            << int(QMetaType::Void) << QByteArray("void")
             << (QList<int>() << 0)
             << (QList<QByteArray>() << QByteArray("CustomUnregisteredType"))
             << (QList<QByteArray>() << QByteArray("voidSlotCustomUnregisteredTypeArg"))
@@ -554,7 +554,7 @@ void tst_QMetaMethod::method_data()
 
     QTest::newRow("voidSignalNoParameterNames")
             << QByteArray("voidSignalNoParameterNames(bool,int)")
-            << int(QMetaType::Void) << QByteArray("")
+            << int(QMetaType::Void) << QByteArray("void")
             << (QList<int>() << int(QMetaType::Bool) << int(QMetaType::Int))
             << (QList<QByteArray>() << QByteArray("bool") << QByteArray("int"))
             << (QList<QByteArray>() << QByteArray("") << QByteArray(""))
@@ -563,7 +563,7 @@ void tst_QMetaMethod::method_data()
 
     QTest::newRow("voidInvokableNoParameterNames")
             << QByteArray("voidInvokableNoParameterNames(bool,int)")
-            << int(QMetaType::Void) << QByteArray("")
+            << int(QMetaType::Void) << QByteArray("void")
             << (QList<int>() << int(QMetaType::Bool) << int(QMetaType::Int))
             << (QList<QByteArray>() << QByteArray("bool") << QByteArray("int"))
             << (QList<QByteArray>() << QByteArray("") << QByteArray(""))
@@ -572,7 +572,7 @@ void tst_QMetaMethod::method_data()
 
     QTest::newRow("voidSlotNoParameterNames")
             << QByteArray("voidSlotNoParameterNames(bool,int)")
-            << int(QMetaType::Void) << QByteArray("")
+            << int(QMetaType::Void) << QByteArray("void")
             << (QList<int>() << int(QMetaType::Bool) << int(QMetaType::Int))
             << (QList<QByteArray>() << QByteArray("bool") << QByteArray("int"))
             << (QList<QByteArray>() << QByteArray("") << QByteArray(""))
@@ -627,6 +627,7 @@ void tst_QMetaMethod::method()
 
     QCOMPARE(method.tag(), "");
     QCOMPARE(method.returnType(), returnType);
+    QVERIFY(method.typeName() != 0);
     if (QByteArray(method.typeName()) != returnTypeName) {
         // QMetaMethod should always produce a semantically equivalent typename
         QCOMPARE(QMetaType::type(method.typeName()), QMetaType::type(returnTypeName));
diff --git a/tests/auto/corelib/kernel/qmetaobjectbuilder/tst_qmetaobjectbuilder.cpp b/tests/auto/corelib/kernel/qmetaobjectbuilder/tst_qmetaobjectbuilder.cpp
index f187425c84..0649d1e1d8 100644
--- a/tests/auto/corelib/kernel/qmetaobjectbuilder/tst_qmetaobjectbuilder.cpp
+++ b/tests/auto/corelib/kernel/qmetaobjectbuilder/tst_qmetaobjectbuilder.cpp
@@ -229,7 +229,7 @@ void tst_QMetaObjectBuilder::method()
     QMetaMethodBuilder method1 = builder.addMethod("foo(const QString&, int)");
     QCOMPARE(method1.signature(), QByteArray("foo(QString,int)"));
     QVERIFY(method1.methodType() == QMetaMethod::Method);
-    QVERIFY(method1.returnType().isEmpty());
+    QCOMPARE(method1.returnType(), QByteArray("void"));
     QCOMPARE(method1.parameterTypes(), QList<QByteArray>() << "QString" << "int");
     QVERIFY(method1.parameterNames().isEmpty());
     QVERIFY(method1.tag().isEmpty());
@@ -354,7 +354,7 @@ void tst_QMetaObjectBuilder::slot()
     QMetaMethodBuilder method1 = builder.addSlot("foo(const QString&, int)");
     QCOMPARE(method1.signature(), QByteArray("foo(QString,int)"));
     QVERIFY(method1.methodType() == QMetaMethod::Slot);
-    QVERIFY(method1.returnType().isEmpty());
+    QCOMPARE(method1.returnType(), QByteArray("void"));
     QCOMPARE(method1.parameterTypes(), QList<QByteArray>() << "QString" << "int");
     QVERIFY(method1.parameterNames().isEmpty());
     QVERIFY(method1.tag().isEmpty());
@@ -367,7 +367,7 @@ void tst_QMetaObjectBuilder::slot()
     QMetaMethodBuilder method2 = builder.addSlot("bar(QString)");
     QCOMPARE(method2.signature(), QByteArray("bar(QString)"));
     QVERIFY(method2.methodType() == QMetaMethod::Slot);
-    QVERIFY(method2.returnType().isEmpty());
+    QCOMPARE(method2.returnType(), QByteArray("void"));
     QCOMPARE(method2.parameterTypes(), QList<QByteArray>() << "QString");
     QVERIFY(method2.parameterNames().isEmpty());
     QVERIFY(method2.tag().isEmpty());
@@ -393,7 +393,7 @@ void tst_QMetaObjectBuilder::signal()
     QMetaMethodBuilder method1 = builder.addSignal("foo(const QString&, int)");
     QCOMPARE(method1.signature(), QByteArray("foo(QString,int)"));
     QVERIFY(method1.methodType() == QMetaMethod::Signal);
-    QVERIFY(method1.returnType().isEmpty());
+    QCOMPARE(method1.returnType(), QByteArray("void"));
     QCOMPARE(method1.parameterTypes(), QList<QByteArray>() << "QString" << "int");
     QVERIFY(method1.parameterNames().isEmpty());
     QVERIFY(method1.tag().isEmpty());
@@ -406,7 +406,7 @@ void tst_QMetaObjectBuilder::signal()
     QMetaMethodBuilder method2 = builder.addSignal("bar(QString)");
     QCOMPARE(method2.signature(), QByteArray("bar(QString)"));
     QVERIFY(method2.methodType() == QMetaMethod::Signal);
-    QVERIFY(method2.returnType().isEmpty());
+    QCOMPARE(method2.returnType(), QByteArray("void"));
     QCOMPARE(method2.parameterTypes(), QList<QByteArray>() << "QString");
     QVERIFY(method2.parameterNames().isEmpty());
     QVERIFY(method2.tag().isEmpty());