QmlDesigner: fix crash at RewriterView::amendQmlText()

RewriterView does not own m_textModifier, so it needs to be checked.
Especially if it is called by a timer like in the amendQmlText() case.

With m_textToModelMerger, its a different story because its
an owned unique_ptr. So no need to check it.

Change-Id: If19b58cc94ec5e8ddd68a8c12acba0f880cbdc6b
Reviewed-by: Thomas Hartmann <thomas.hartmann@qt.io>
(cherry picked from commit 6bcf4c9dc7)
Reviewed-by: Tim Jenssen <tim.jenssen@qt.io>

src/plugins/qmldesigner/designercore/include/rewriterview.h

@@ -196,7 +196,7 @@ private: //variables
     void handleProjectUpdate();
     bool inErrorState() const { return !m_rewritingErrorMessage.isEmpty(); }
 
-    TextModifier *m_textModifier = nullptr;
+    QPointer<TextModifier> m_textModifier;
     int transactionLevel = 0;
     bool m_modificationGroupActive = false;
     bool m_checkSemanticErrors = true;

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

@@ -88,6 +88,7 @@ Internal::TextToModelMerger *RewriterView::textToModelMerger() const
 
 void RewriterView::modelAttached(Model *model)
 {
+    QTC_ASSERT(m_textModifier, return);
     m_modelAttachPending = false;
 
     AbstractView::modelAttached(model);
@@ -431,7 +432,7 @@ void RewriterView::deactivateTextMofifierChangeSignals()
 
 void RewriterView::auxiliaryDataChanged(const ModelNode &, AuxiliaryDataKeyView key, const QVariant &)
 {
-    if (m_restoringAuxData)
+    if (m_restoringAuxData || !m_textModifier)
         return;
 
     if (key.type == AuxiliaryDataType::Document)
@@ -488,9 +489,9 @@ void RewriterView::amendQmlText()
 
     if (!model()->rewriterView())
         return;
+    QTC_ASSERT(m_textModifier, return);
 
     emitCustomNotification(StartRewriterAmend);
-
     const QString newQmlText = m_textModifier->text();
 
     ModelAmender differenceHandler(m_textToModelMerger.data());
@@ -754,6 +755,7 @@ void RewriterView::enterErrorState(const QString &errorMessage)
 
 void RewriterView::resetToLastCorrectQml()
 {
+    QTC_ASSERT(m_textModifier, return);
     m_textModifier->textDocument()->undo();
     m_textModifier->textDocument()->clearUndoRedoStacks(QTextDocument::RedoStack);
     ModelAmender differenceHandler(m_textToModelMerger.data());
@@ -766,6 +768,7 @@ void RewriterView::resetToLastCorrectQml()
 
 QMap<ModelNode, QString> RewriterView::extractText(const QList<ModelNode> &nodes) const
 {
+    QTC_ASSERT(m_textModifier, return {});
     QmlDesigner::ASTObjectTextExtractor extract(m_textModifier->text());
     QMap<ModelNode, QString> result;
 
@@ -792,6 +795,7 @@ int RewriterView::nodeOffset(const ModelNode &node) const
  */
 int RewriterView::nodeLength(const ModelNode &node) const
 {
+    QTC_ASSERT(m_textModifier, return -1);
     ObjectLengthCalculator objectLengthCalculator;
     unsigned length;
     if (objectLengthCalculator(m_textModifier->text(), nodeOffset(node), length))
@@ -802,12 +806,14 @@ int RewriterView::nodeLength(const ModelNode &node) const
 
 int RewriterView::firstDefinitionInsideOffset(const ModelNode &node) const
 {
+    QTC_ASSERT(m_textModifier, return -1);
     FirstDefinitionFinder firstDefinitionFinder(m_textModifier->text());
     return firstDefinitionFinder(nodeOffset(node));
 }
 
 int RewriterView::firstDefinitionInsideLength(const ModelNode &node) const
 {
+    QTC_ASSERT(m_textModifier, return -1);
     FirstDefinitionFinder firstDefinitionFinder(m_textModifier->text());
     const int offset =  firstDefinitionFinder(nodeOffset(node));
 
@@ -831,6 +837,7 @@ static bool isInNodeDefinition(int nodeTextOffset, int nodeTextLength, int curso
 
 ModelNode RewriterView::nodeAtTextCursorPositionHelper(const ModelNode &root, int cursorPosition) const
 {
+    QTC_ASSERT(m_textModifier, return {});
     using myPair = std::pair<ModelNode,int>;
     std::vector<myPair> data;
 
@@ -1080,8 +1087,8 @@ void RewriterView::qmlTextChanged()
 {
     if (inErrorState())
         return;
+    QTC_ASSERT(m_textModifier, return);
 
-    if (m_textToModelMerger && m_textModifier) {
     const QString newQmlText = m_textModifier->text();
 
 #if 0
@@ -1110,7 +1117,6 @@ void RewriterView::qmlTextChanged()
         break;
     }
     }
-    }
 }
 
 void RewriterView::delayedSetup()