Rename QMetaMethod::signature() to methodSignature()

In Qt5 the meta-data format will be changed to not store the
method signature string explicitly; the signature will be
reconstructed on demand from the method name and parameter type
information.

The QMetaMethod::signature() method returns a const char pointer.
Changing the return type to QByteArray can lead to silent bugs due to
the implicit conversion to char *. Even though it's a source-
incompatible change, it's therefore better to introduce a new
function, methodSignature(), and remove the old signature().

Task-number: QTBUG-24154
Change-Id: Ib3579dedd27a3c7c8914d5f1b231947be2cf4027
Reviewed-by: Olivier Goffart <ogoffart@woboq.com>
Reviewed-by: Lars Knoll <lars.knoll@nokia.com>
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>
Reviewed-by: João Abecasis <joao.abecasis@nokia.com>

5 files changed, 54 insertions, 39 deletions

diff --git a/src/corelib/kernel/qmetaobject.cpp b/src/corelib/kernel/qmetaobject.cpp
index ce30e34f73..4d629dd933 100644
--- a/src/corelib/kernel/qmetaobject.cpp
+++ b/src/corelib/kernel/qmetaobject.cpp
@@ -157,6 +157,11 @@ static inline const QByteArrayData &stringData(const QMetaObject *mo, int index)
     return data;
 }
 
+static inline QByteArray toByteArray(const QByteArrayData &d)
+{
+    return QByteArray(reinterpret_cast<const QStaticByteArrayData<0> &>(d));
+}
+
 static inline const char *legacyString(const QMetaObject *mo, int index)
 {
     Q_ASSERT(priv(mo->d.data)->revision <= 6);
@@ -1268,7 +1273,7 @@ bool QMetaObject::invokeMethod(QObject *obj,
 
     \ingroup objectmodel
 
-    A QMetaMethod has a methodType(), a signature(), a list of
+    A QMetaMethod has a methodType(), a methodSignature(), a list of
     parameterTypes() and parameterNames(), a return typeName(), a
     tag(), and an access() specifier. You can use invoke() to invoke
     the method on an arbitrary QObject.
@@ -1314,22 +1319,24 @@ bool QMetaObject::invokeMethod(QObject *obj,
 */
 
 /*!
+    \since 5.0
+
     Returns the signature of this method (e.g.,
     \c{setValue(double)}).
 
     \sa parameterTypes(), parameterNames()
 */
-const char *QMetaMethod::signature() const
+QByteArray QMetaMethod::methodSignature() const
 {
     if (!mobj)
-        return 0;
-    return rawStringData(mobj, mobj->d.data[handle]);
+        return QByteArray();
+    return toByteArray(stringData(mobj, mobj->d.data[handle]));
 }
 
 /*!
     Returns a list of parameter types.
 
-    \sa parameterNames(), signature()
+    \sa parameterNames(), methodSignature()
 */
 QList<QByteArray> QMetaMethod::parameterTypes() const
 {
@@ -1342,7 +1349,7 @@ QList<QByteArray> QMetaMethod::parameterTypes() const
 /*!
     Returns a list of parameter names.
 
-    \sa parameterTypes(), signature()
+    \sa parameterTypes(), methodSignature()
 */
 QList<QByteArray> QMetaMethod::parameterNames() const
 {
diff --git a/src/corelib/kernel/qmetaobject.h b/src/corelib/kernel/qmetaobject.h
index 9e51af7556..573e69fdb7 100644
--- a/src/corelib/kernel/qmetaobject.h
+++ b/src/corelib/kernel/qmetaobject.h
@@ -57,7 +57,7 @@ class Q_CORE_EXPORT QMetaMethod
 public:
     inline QMetaMethod() : mobj(0),handle(0) {}
 
-    const char *signature() const;
+    QByteArray methodSignature() const;
     const char *typeName() const;
     QList<QByteArray> parameterTypes() const;
     QList<QByteArray> parameterNames() const;
@@ -137,6 +137,13 @@ public:
     inline bool isValid() const { return mobj != 0; }
 
 private:
+#if QT_DEPRECATED_SINCE(5,0)
+    // signature() has been renamed to methodSignature() in Qt 5.
+    // Warning, that function returns a QByteArray; check the life time if
+    // you convert to char*.
+    char *signature(struct renamedInQt5_warning_checkTheLifeTime * = 0) Q_DECL_EQ_DELETE;
+#endif
+
     const QMetaObject *mobj;
     uint handle;
     friend struct QMetaObject;
diff --git a/src/corelib/kernel/qmetaobjectbuilder.cpp b/src/corelib/kernel/qmetaobjectbuilder.cpp
index 8bece6636b..82c74a34f3 100644
--- a/src/corelib/kernel/qmetaobjectbuilder.cpp
+++ b/src/corelib/kernel/qmetaobjectbuilder.cpp
@@ -458,13 +458,13 @@ QMetaMethodBuilder QMetaObjectBuilder::addMethod(const QMetaMethod& prototype)
 {
     QMetaMethodBuilder method;
     if (prototype.methodType() == QMetaMethod::Method)
-        method = addMethod(prototype.signature());
+        method = addMethod(prototype.methodSignature());
     else if (prototype.methodType() == QMetaMethod::Signal)
-        method = addSignal(prototype.signature());
+        method = addSignal(prototype.methodSignature());
     else if (prototype.methodType() == QMetaMethod::Slot)
-        method = addSlot(prototype.signature());
+        method = addSlot(prototype.methodSignature());
     else if (prototype.methodType() == QMetaMethod::Constructor)
-        method = addConstructor(prototype.signature());
+        method = addConstructor(prototype.methodSignature());
     method.setReturnType(prototype.typeName());
     method.setParameterNames(prototype.parameterNames());
     method.setTag(prototype.tag());
@@ -535,7 +535,7 @@ QMetaMethodBuilder QMetaObjectBuilder::addConstructor(const QByteArray& signatur
 QMetaMethodBuilder QMetaObjectBuilder::addConstructor(const QMetaMethod& prototype)
 {
     Q_ASSERT(prototype.methodType() == QMetaMethod::Constructor);
-    QMetaMethodBuilder ctor = addConstructor(prototype.signature());
+    QMetaMethodBuilder ctor = addConstructor(prototype.methodSignature());
     ctor.setReturnType(prototype.typeName());
     ctor.setParameterNames(prototype.parameterNames());
     ctor.setTag(prototype.tag());
@@ -588,7 +588,7 @@ QMetaPropertyBuilder QMetaObjectBuilder::addProperty(const QMetaProperty& protot
     if (prototype.hasNotifySignal()) {
         // Find an existing method for the notify signal, or add a new one.
         QMetaMethod method = prototype.notifySignal();
-        int index = indexOfMethod(method.signature());
+        int index = indexOfMethod(method.methodSignature());
         if (index == -1)
             index = addMethod(method).index();
         d->properties[property._index].notifySignal = index;
diff --git a/src/corelib/kernel/qobject.cpp b/src/corelib/kernel/qobject.cpp
index d8c82ddc9f..f44e4c4761 100644
--- a/src/corelib/kernel/qobject.cpp
+++ b/src/corelib/kernel/qobject.cpp
@@ -2174,12 +2174,12 @@ static inline void check_and_warn_compat(const QMetaObject *sender, const QMetaM
     if (signal.attributes() & QMetaMethod::Compatibility) {
         if (!(method.attributes() & QMetaMethod::Compatibility))
             qWarning("QObject::connect: Connecting from COMPAT signal (%s::%s)",
-                     sender->className(), signal.signature());
+                     sender->className(), signal.methodSignature().constData());
     } else if ((method.attributes() & QMetaMethod::Compatibility) &&
                method.methodType() == QMetaMethod::Signal) {
         qWarning("QObject::connect: Connecting from %s::%s to COMPAT slot (%s::%s)",
-                 sender->className(), signal.signature(),
-                 receiver->className(), method.signature());
+                 sender->className(), signal.methodSignature().constData(),
+                 receiver->className(), method.methodSignature().constData());
     }
 }
 
@@ -2419,17 +2419,17 @@ QMetaObject::Connection QObject::connect(const QObject *sender, const QMetaMetho
             || method.methodType() == QMetaMethod::Constructor) {
         qWarning("QObject::connect: Cannot connect %s::%s to %s::%s",
                  sender ? sender->metaObject()->className() : "(null)",
-                 signal.signature(),
+                 signal.methodSignature().constData(),
                  receiver ? receiver->metaObject()->className() : "(null)",
-                 method.signature() );
+                 method.methodSignature().constData() );
         return QMetaObject::Connection(0);
     }
 
-    // Reconstructing SIGNAL() macro result for signal.signature() string
+    // Reconstructing SIGNAL() macro result for signal.methodSignature() string
     QByteArray signalSignature;
-    signalSignature.reserve(qstrlen(signal.signature())+1);
+    signalSignature.reserve(signal.methodSignature().size()+1);
     signalSignature.append((char)(QSIGNAL_CODE + '0'));
-    signalSignature.append(signal.signature());
+    signalSignature.append(signal.methodSignature());
 
     int signal_index;
     int method_index;
@@ -2443,20 +2443,20 @@ QMetaObject::Connection QObject::connect(const QObject *sender, const QMetaMetho
     const QMetaObject *rmeta = receiver->metaObject();
     if (signal_index == -1) {
         qWarning("QObject::connect: Can't find signal %s on instance of class %s",
-                 signal.signature(), smeta->className());
+                 signal.methodSignature().constData(), smeta->className());
         return QMetaObject::Connection(0);
     }
     if (method_index == -1) {
         qWarning("QObject::connect: Can't find method %s on instance of class %s",
-                 method.signature(), rmeta->className());
+                 method.methodSignature().constData(), rmeta->className());
         return QMetaObject::Connection(0);
     }
 
-    if (!QMetaObject::checkConnectArgs(signal.signature(), method.signature())) {
+    if (!QMetaObject::checkConnectArgs(signal.methodSignature().constData(), method.methodSignature().constData())) {
         qWarning("QObject::connect: Incompatible sender/receiver arguments"
                  "\n        %s::%s --> %s::%s",
-                 smeta->className(), signal.signature(),
-                 rmeta->className(), method.signature());
+                 smeta->className(), signal.methodSignature().constData(),
+                 rmeta->className(), method.methodSignature().constData());
         return QMetaObject::Connection(0);
     }
 
@@ -2688,24 +2688,24 @@ bool QObject::disconnect(const QObject *sender, const QMetaMethod &signal,
         if(signal.methodType() != QMetaMethod::Signal) {
             qWarning("QObject::%s: Attempt to %s non-signal %s::%s",
                      "disconnect","unbind",
-                     sender->metaObject()->className(), signal.signature());
+                     sender->metaObject()->className(), signal.methodSignature().constData());
             return false;
         }
     }
     if (method.mobj) {
         if(method.methodType() == QMetaMethod::Constructor) {
             qWarning("QObject::disconect: cannot use constructor as argument %s::%s",
-                     receiver->metaObject()->className(), method.signature());
+                     receiver->metaObject()->className(), method.methodSignature().constData());
             return false;
         }
     }
 
-    // Reconstructing SIGNAL() macro result for signal.signature() string
+    // Reconstructing SIGNAL() macro result for signal.methodSignature() string
     QByteArray signalSignature;
     if (signal.mobj) {
-        signalSignature.reserve(qstrlen(signal.signature())+1);
+        signalSignature.reserve(signal.methodSignature().size()+1);
         signalSignature.append((char)(QSIGNAL_CODE + '0'));
-        signalSignature.append(signal.signature());
+        signalSignature.append(signal.methodSignature());
     }
 
     int signal_index;
@@ -2719,13 +2719,13 @@ bool QObject::disconnect(const QObject *sender, const QMetaMethod &signal,
     // is -1 then this signal is not a member of sender.
     if (signal.mobj && signal_index == -1) {
         qWarning("QObject::disconect: signal %s not found on class %s",
-                 signal.signature(), sender->metaObject()->className());
+                 signal.methodSignature().constData(), sender->metaObject()->className());
         return false;
     }
     // If this condition is true then method is not a member of receeiver.
     if (receiver && method.mobj && method_index == -1) {
         qWarning("QObject::disconect: method %s not found on class %s",
-                 method.signature(), receiver->metaObject()->className());
+                 method.methodSignature().constData(), receiver->metaObject()->className());
         return false;
     }
 
@@ -3040,7 +3040,8 @@ void QMetaObject::connectSlotsByName(QObject *o)
     Q_ASSERT(mo);
     const QObjectList list = o->findChildren<QObject *>(QString());
     for (int i = 0; i < mo->methodCount(); ++i) {
-        const char *slot = mo->method(i).signature();
+        QByteArray slotSignature = mo->method(i).methodSignature();
+        const char *slot = slotSignature.constData();
         Q_ASSERT(slot);
         if (slot[0] != 'o' || slot[1] != 'n' || slot[2] != '_')
             continue;
@@ -3060,7 +3061,7 @@ void QMetaObject::connectSlotsByName(QObject *o)
                     if (method.methodType() != QMetaMethod::Signal)
                         continue;
 
-                    if (!qstrncmp(method.signature(), slot + len + 4, slotlen)) {
+                    if (!qstrncmp(method.methodSignature().constData(), slot + len + 4, slotlen)) {
                         int signalOffset, methodOffset;
                         computeOffsets(method.enclosingMetaObject(), &signalOffset, &methodOffset);
                         sigIndex = k + - methodOffset + signalOffset;
@@ -3531,7 +3532,7 @@ void QObject::dumpObjectInfo()
                 offset = methodOffset - signalOffset;
             }
             const QMetaMethod signal = metaObject()->method(signal_index + offset);
-            qDebug("        signal: %s", signal.signature());
+            qDebug("        signal: %s", signal.methodSignature().constData());
 
             // receivers
             const QObjectPrivate::Connection *c =
@@ -3547,7 +3548,7 @@ void QObject::dumpObjectInfo()
                 qDebug("          --> %s::%s %s",
                        receiverMetaObject->className(),
                        c->receiver->objectName().isEmpty() ? "unnamed" : qPrintable(c->receiver->objectName()),
-                       method.signature());
+                       method.methodSignature().constData());
                 c = c->nextConnectionList;
             }
         }
@@ -3564,7 +3565,7 @@ void QObject::dumpObjectInfo()
             qDebug("          <-- %s::%s  %s",
                    s->sender->metaObject()->className(),
                    s->sender->objectName().isEmpty() ? "unnamed" : qPrintable(s->sender->objectName()),
-                   slot.signature());
+                   slot.methodSignature().constData());
         }
     } else {
         qDebug("        <None>");
diff --git a/src/corelib/statemachine/qstatemachine.cpp b/src/corelib/statemachine/qstatemachine.cpp
index 7ff005f9a1..3992c4060e 100644
--- a/src/corelib/statemachine/qstatemachine.cpp
+++ b/src/corelib/statemachine/qstatemachine.cpp
@@ -1657,7 +1657,7 @@ void QStateMachinePrivate::handleTransitionSignal(QObject *sender, int signalInd
 
 #ifdef QSTATEMACHINE_DEBUG
     qDebug() << q_func() << ": sending signal event ( sender =" << sender
-             << ", signal =" << sender->metaObject()->method(signalIndex).signature() << ')';
+             << ", signal =" << sender->metaObject()->method(signalIndex).methodSignature().constData() << ')';
 #endif
     postInternalEvent(new QStateMachine::SignalEvent(sender, signalIndex, vargs));
     processEvents(DirectProcessing);