QDBus: improve error handling, to give the developer feedback.

For instance, exporting an object with a slot like
   QString complexMethod(const MyVariantMap& vars);
   (even with a simple typedef QVariantMap MyVariantMap)
used to silently skip that method in the introspection.
Now it outputs:
 generateInterfaceXml: Skipped method "complexMethod" : Invalid type in parameter list: MyVariantMap

Change-Id: I7964cfb63e973257ce1abe47b9625e361b2ad23f
Reviewed-by: Kevin Ottens <kevin.ottens@kdab.com>
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>

6 files changed, 43 insertions, 28 deletions

diff --git a/src/dbus/qdbusabstractadaptor.cpp b/src/dbus/qdbusabstractadaptor.cpp
index e08714f04d..1dbc79d6ec 100644
--- a/src/dbus/qdbusabstractadaptor.cpp
+++ b/src/dbus/qdbusabstractadaptor.cpp
@@ -298,15 +298,18 @@ void QDBusAdaptorConnector::relay(QObject *senderObj, int lastSignalIdx, void **
 
     // break down the parameter list
     QVector<int> types;
-    int inputCount = qDBusParametersForMethod(mm, types);
-    if (inputCount == -1)
+    QString errorMsg;
+    int inputCount = qDBusParametersForMethod(mm, types, errorMsg);
+    if (inputCount == -1) {
         // invalid signal signature
-        // qDBusParametersForMethod has already complained
+        qWarning("QDBusAbstractAdaptor: Cannot relay signal %s::%s: %s",
+                 senderMetaObject->className(), mm.methodSignature().constData(),
+                 qPrintable(errorMsg));
         return;
+    }
     if (inputCount + 1 != types.count() ||
         types.at(inputCount) == QDBusMetaTypeId::message()) {
         // invalid signal signature
-        // qDBusParametersForMethod has not yet complained about this one
         qWarning("QDBusAbstractAdaptor: Cannot relay signal %s::%s",
                  senderMetaObject->className(), mm.methodSignature().constData());
         return;
diff --git a/src/dbus/qdbusconnection_p.h b/src/dbus/qdbusconnection_p.h
index 73c8dcf411..48026e15bd 100644
--- a/src/dbus/qdbusconnection_p.h
+++ b/src/dbus/qdbusconnection_p.h
@@ -342,9 +342,9 @@ public:
 };
 
 // in qdbusmisc.cpp
-extern int qDBusParametersForMethod(const QMetaMethod &mm, QVector<int> &metaTypes);
+extern int qDBusParametersForMethod(const QMetaMethod &mm, QVector<int> &metaTypes, QString &errorMsg);
 #endif // QT_BOOTSTRAPPED
-extern Q_DBUS_EXPORT int qDBusParametersForMethod(const QList<QByteArray> &parameters, QVector<int>& metaTypes);
+extern Q_DBUS_EXPORT int qDBusParametersForMethod(const QList<QByteArray> &parameters, QVector<int>& metaTypes, QString &errorMsg);
 extern Q_DBUS_EXPORT bool qDBusCheckAsyncTag(const char *tag);
 #ifndef QT_BOOTSTRAPPED
 extern bool qDBusInterfaceInObject(QObject *obj, const QString &interface_name);
diff --git a/src/dbus/qdbusintegrator.cpp b/src/dbus/qdbusintegrator.cpp
index afb8506b28..e0aec2cad9 100644
--- a/src/dbus/qdbusintegrator.cpp
+++ b/src/dbus/qdbusintegrator.cpp
@@ -721,7 +721,8 @@ static int findSlot(const QMetaObject *mo, const QByteArray &name, int flags,
         if (isAsync && returnType != QMetaType::Void)
             continue;
 
-        int inputCount = qDBusParametersForMethod(mm, metaTypes);
+        QString errorMsg;
+        int inputCount = qDBusParametersForMethod(mm, metaTypes, errorMsg);
         if (inputCount == -1)
             continue;           // problem parsing
 
@@ -1312,7 +1313,8 @@ int QDBusConnectionPrivate::findSlot(QObject* obj, const QByteArray &normalizedN
     if (midx == -1)
         return -1;
 
-    int inputCount = qDBusParametersForMethod(obj->metaObject()->method(midx), params);
+    QString errorMsg;
+    int inputCount = qDBusParametersForMethod(obj->metaObject()->method(midx), params, errorMsg);
     if ( inputCount == -1 || inputCount + 1 != params.count() )
         return -1;              // failed to parse or invalid arguments or output arguments
 
diff --git a/src/dbus/qdbusmisc.cpp b/src/dbus/qdbusmisc.cpp
index d28d5598c6..5d3512845a 100644
--- a/src/dbus/qdbusmisc.cpp
+++ b/src/dbus/qdbusmisc.cpp
@@ -131,14 +131,14 @@ bool qDBusInterfaceInObject(QObject *obj, const QString &interface_name)
 // metaTypes.count() >= retval + 1 in all cases
 //
 // sig must be the normalised signature for the method
-int qDBusParametersForMethod(const QMetaMethod &mm, QVector<int> &metaTypes)
+int qDBusParametersForMethod(const QMetaMethod &mm, QVector<int> &metaTypes, QString &errorMsg)
 {
-    return qDBusParametersForMethod(mm.parameterTypes(), metaTypes);
+    return qDBusParametersForMethod(mm.parameterTypes(), metaTypes, errorMsg);
 }
 
 #endif // QT_BOOTSTRAPPED
 
-int qDBusParametersForMethod(const QList<QByteArray> &parameterTypes, QVector<int>& metaTypes)
+int qDBusParametersForMethod(const QList<QByteArray> &parameterTypes, QVector<int>& metaTypes, QString &errorMsg)
 {
     QDBusMetaTypeId::init();
     metaTypes.clear();
@@ -151,8 +151,7 @@ int qDBusParametersForMethod(const QList<QByteArray> &parameterTypes, QVector<in
     for ( ; it != end; ++it) {
         const QByteArray &type = *it;
         if (type.endsWith('*')) {
-            //qWarning("Could not parse the method '%s'", mm.methodSignature().constData());
-            // pointer?
+            errorMsg = QLatin1String("Pointers are not supported: ") + QLatin1String(type);
             return -1;
         }
 
@@ -162,8 +161,7 @@ int qDBusParametersForMethod(const QList<QByteArray> &parameterTypes, QVector<in
 
             int id = QMetaType::type(basictype);
             if (id == 0) {
-                //qWarning("Could not parse the method '%s'", mm.methodSignature().constData());
-                // invalid type in method parameter list
+                errorMsg = QLatin1String("Unregistered output type in parameter list: ") + QLatin1String(type);
                 return -1;
             } else if (QDBusMetaType::typeToSignature(id) == 0)
                 return -1;
@@ -174,22 +172,22 @@ int qDBusParametersForMethod(const QList<QByteArray> &parameterTypes, QVector<in
         }
 
         if (seenMessage) {      // && !type.endsWith('&')
-            //qWarning("Could not parse the method '%s'", mm.methodSignature().constData());
-            // non-output parameters after message or after output params
+            errorMsg = QLatin1String("Invalid method, non-output parameters after message or after output parameters: ") + QLatin1String(type);
             return -1;          // not allowed
         }
 
         int id = QMetaType::type(type);
         if (id == QMetaType::UnknownType) {
-            //qWarning("Could not parse the method '%s'", mm.methodSignature().constData());
-            // invalid type in method parameter list
+            errorMsg = QLatin1String("Unregistered input type in parameter list: ") + QLatin1String(type);
             return -1;
         }
 
         if (id == QDBusMetaTypeId::message())
             seenMessage = true;
-        else if (QDBusMetaType::typeToSignature(id) == 0)
+        else if (QDBusMetaType::typeToSignature(id) == 0) {
+            errorMsg = QLatin1String("Type not registered with QtDBus in parameter list: ") + QLatin1String(type);
             return -1;
+        }
 
         metaTypes.append(id);
         ++inputCount;
diff --git a/src/dbus/qdbusxmlgenerator.cpp b/src/dbus/qdbusxmlgenerator.cpp
index 387caae957..fcdf43da4d 100644
--- a/src/dbus/qdbusxmlgenerator.cpp
+++ b/src/dbus/qdbusxmlgenerator.cpp
@@ -41,6 +41,7 @@
 
 #include <QtCore/qmetaobject.h>
 #include <QtCore/qstringlist.h>
+#include <QtCore/qdebug.h>
 
 #include "qdbusinterface_p.h"   // for ANNOTATION_NO_WAIT
 #include "qdbusabstractadaptor_p.h" // for QCLASSINFO_DBUS_*
@@ -159,17 +160,24 @@ static QString generateInterfaceXml(const QMetaObject *mo, int flags, int method
                 if (QDBusMetaType::signatureToType(typeName) == QVariant::Invalid)
                     xml += QString::fromLatin1("      <annotation name=\"org.qtproject.QtDBus.QtTypeName.Out0\" value=\"%1\"/>\n")
                         .arg(typeNameToXml(QMetaType::typeName(typeId)));
-            } else
+            } else {
+                qWarning() << "Unsupported return type" << typeId << QMetaType::typeName(typeId) << "in method" << mm.name();
                 continue;
+            }
         }
-        else if (typeId == QMetaType::UnknownType)
+        else if (typeId == QMetaType::UnknownType) {
+            qWarning() << "Invalid return type in method" << mm.name();
             continue;           // wasn't a valid type
+        }
 
         QList<QByteArray> names = mm.parameterNames();
         QVector<int> types;
-        int inputCount = qDBusParametersForMethod(mm, types);
-        if (inputCount == -1)
+        QString errorMsg;
+        int inputCount = qDBusParametersForMethod(mm, types, errorMsg);
+        if (inputCount == -1) {
+            qWarning() << "Skipped method" << mm.name() << ":" << qPrintable(errorMsg);
             continue;           // invalid form
+        }
         if (isSignal && inputCount + 1 != types.count())
             continue;           // signal with output arguments?
         if (isSignal && types.at(inputCount) == QDBusMetaTypeId::message())
diff --git a/src/tools/qdbuscpp2xml/qdbuscpp2xml.cpp b/src/tools/qdbuscpp2xml/qdbuscpp2xml.cpp
index a66757907d..0e1fa59b90 100644
--- a/src/tools/qdbuscpp2xml/qdbuscpp2xml.cpp
+++ b/src/tools/qdbuscpp2xml/qdbuscpp2xml.cpp
@@ -47,6 +47,7 @@
 #include <qbuffer.h>
 #include <qregexp.h>
 #include <qvector.h>
+#include <qdebug.h>
 
 #include <stdio.h>
 #include <stdlib.h>
@@ -95,14 +96,14 @@ static const char help[] =
     "\n";
 
 
-int qDBusParametersForMethod(const FunctionDef &mm, QVector<int>& metaTypes)
+int qDBusParametersForMethod(const FunctionDef &mm, QVector<int>& metaTypes, QString &errorMsg)
 {
     QList<QByteArray> parameterTypes;
 
     foreach (const ArgumentDef &arg, mm.arguments)
         parameterTypes.append(arg.normalizedType);
 
-    return qDBusParametersForMethod(parameterTypes, metaTypes);
+    return qDBusParametersForMethod(parameterTypes, metaTypes, errorMsg);
 }
 
 
@@ -140,9 +141,12 @@ static QString addFunction(const FunctionDef &mm, bool isSignal = false) {
     }
     QList<ArgumentDef> names = mm.arguments;
     QVector<int> types;
-    int inputCount = qDBusParametersForMethod(mm, types);
-    if (inputCount == -1)
+    QString errorMsg;
+    int inputCount = qDBusParametersForMethod(mm, types, errorMsg);
+    if (inputCount == -1) {
+        qWarning() << qPrintable(errorMsg);
         return QString();           // invalid form
+    }
     if (isSignal && inputCount + 1 != types.count())
         return QString();           // signal with output arguments?
     if (isSignal && types.at(inputCount) == QDBusMetaTypeId::message())