QmlJS: Add error message for invalid root item in the designer

Documents with those types do crash the qmlpuppet and confuse the users.
With this patch we give a clear error message and such files are not supported
anymore.

Change-Id: Iba19def2751d4dc81d90684c0c63c0274fdf49cf
Reviewed-by: Fawzi Mohamed <fawzi.mohamed@digia.com>

src/libs/qmljs/qmljscheck.cpp

@@ -525,10 +525,24 @@ public:
     }
 
 };
+
+class UnsupportedRootObjectTypesByVisualDesigner : public QStringList
+{
+public:
+    UnsupportedRootObjectTypesByVisualDesigner()
+    {
+        (*this) << QLatin1String("QtObject") << QLatin1String("ListModel")
+            << QLatin1String("Component") << QLatin1String("Timer")
+            << QLatin1String("Package");
+    }
+
+};
+
 } // end of anonymous namespace
 
 Q_GLOBAL_STATIC(VisualAspectsPropertyBlackList, visualAspectsPropertyBlackList)
 Q_GLOBAL_STATIC(UnsupportedTypesByVisualDesigner, unsupportedTypesByVisualDesigner)
+Q_GLOBAL_STATIC(UnsupportedRootObjectTypesByVisualDesigner, unsupportedRootObjectTypesByVisualDesigner)
 
 Check::Check(Document::Ptr doc, const ContextPtr &context)
     : _doc(doc)
@@ -559,6 +573,7 @@ Check::Check(Document::Ptr doc, const ContextPtr &context)
     disableMessage(WarnReferenceToParentItemNotSupportedByVisualDesigner);
     disableMessage(WarnUndefinedValueForVisualDesigner);
     disableMessage(WarnStatesOnlyInRootItemForVisualDesigner);
+    disableMessage(ErrUnsupportedRootTypeInVisualDesigner);
 }
 
 Check::~Check()
@@ -729,6 +744,13 @@ void Check::visitQmlObject(Node *ast, UiQualifiedId *typeId,
     if (m_typeStack.count() > 1 && getRightMostIdentifier(typeId)->name.toString() == QLatin1String("State"))
         addMessage(WarnStatesOnlyInRootItemForVisualDesigner, typeErrorLocation);
 
+    const QString typeName = getRightMostIdentifier(typeId)->name.toString();
+
+    if (m_typeStack.isEmpty()
+            && unsupportedRootObjectTypesByVisualDesigner()->contains(typeName))
+        addMessage(ErrUnsupportedRootTypeInVisualDesigner,
+                   locationFromRange(ast->firstSourceLocation(), ast->lastSourceLocation()), typeName);
+
     bool typeError = false;
     if (_importsOk) {
         const ObjectValue *prototype = _context->lookupType(_doc.data(), typeId);

src/libs/qmljs/qmljsstaticanalysismessage.cpp

@@ -221,6 +221,8 @@ StaticAnalysisMessages::StaticAnalysisMessages()
             tr("Qt Quick Designer only supports states in the root item."));
     newMsg(WarnAboutQtQuick1InsteadQtQuick2, Warning,
             tr("Using Qt Quick 1 code model instead of Qt Quick 2."));
+    newMsg(ErrUnsupportedRootTypeInVisualDesigner, Error,
+           tr("This type is not supported as a root element by Qt Quick Designer %1."), 1);
 }
 
 } // anonymous namespace

src/libs/qmljs/qmljsstaticanalysismessage.h

@@ -97,6 +97,7 @@ enum Type
     WarnReferenceToParentItemNotSupportedByVisualDesigner = 205,
     WarnUndefinedValueForVisualDesigner = 206,
     WarnStatesOnlyInRootItemForVisualDesigner = 207,
+    ErrUnsupportedRootTypeInVisualDesigner = 208,
     ErrUnknownComponent = 300,
     ErrCouldNotResolvePrototypeOf = 301,
     ErrCouldNotResolvePrototype = 302,

src/plugins/qmldesigner/designercore/model/texttomodelmerger.cpp

@@ -902,6 +902,7 @@ bool TextToModelMerger::load(const QString &data, DifferenceHandler &differenceH
             check.enableMessage(StaticAnalysis::WarnReferenceToParentItemNotSupportedByVisualDesigner);
             check.enableMessage(StaticAnalysis::WarnReferenceToParentItemNotSupportedByVisualDesigner);
             check.enableMessage(StaticAnalysis::WarnAboutQtQuick1InsteadQtQuick2);
+            check.enableMessage(StaticAnalysis::ErrUnsupportedRootTypeInVisualDesigner);
             //## triggers too often ## check.enableMessage(StaticAnalysis::WarnUndefinedValueForVisualDesigner);
 
             foreach (const StaticAnalysis::Message &message, check()) {