Lint: fix several issues discovered by clazy

src/App/Graphviz.cpp

@@ -399,11 +399,11 @@ void Document::exportGraphviz(std::ostream& out) const
             }
 
             // Internal document objects
-            for (auto It : d->objectMap)
+            for (const auto & It : d->objectMap)
                 addExpressionSubgraphIfNeeded(It.second, CSSubgraphs);
 
             // Add external document objects
-            for (auto it : d->objectMap) {
+            for (const auto & it : d->objectMap) {
                 std::vector<DocumentObject*> OutList = it.second->getOutList();
                 for (auto obj : OutList) {
                     if (obj) {
@@ -424,11 +424,11 @@ void Document::exportGraphviz(std::ostream& out) const
             bool CSSubgraphs = depGrp->GetBool("GeoFeatureSubgraphs", true);
 
             // Add internal document objects
-            for (auto It : d->objectMap)
+            for (const auto & It : d->objectMap)
                 add(It.second, It.second->getNameInDocument(), It.second->Label.getValue(), CSSubgraphs);
 
             // Add external document objects
-            for (auto It : d->objectMap) {
+            for (const auto & It : d->objectMap) {
                 std::vector<DocumentObject*> OutList = It.second->getOutList();
                 for (auto obj : OutList) {
                     if (obj) {
@@ -484,7 +484,7 @@ void Document::exportGraphviz(std::ostream& out) const
             bool omitGeoFeatureGroups = depGrp->GetBool("GeoFeatureSubgraphs", true);
 
             // Add edges between document objects
-            for (auto It : d->objectMap) {
+            for (const auto & It : d->objectMap) {
 
                 if(omitGeoFeatureGroups) {
                     //coordinate systems are represented by subgraphs

src/Base/Rotation.cpp

@@ -842,7 +842,6 @@ struct EulerSequence_Parameters
 
 EulerSequence_Parameters translateEulerSequence (const Rotation::EulerSequence theSeq)
 {
-    using Params = EulerSequence_Parameters;
     const bool F = false;
     const bool T = true;
 

src/Gui/DocumentModel.cpp

@@ -489,7 +489,7 @@ void DocumentModel::slotChangeObject(const Gui::ViewProviderDocumentObject& obj,
             auto doc_index = static_cast<DocumentIndex*>(d->rootItem->child(row));
             QList<ViewProviderIndex*> views;
             doc_index->findViewProviders(obj, views);
-            for (const auto & view : views) {
+            for (const auto & view : qAsConst(views)) {
                 DocumentModelIndex* parentitem = view->parent();
                 QModelIndex parent = createIndex(0,0,parentitem);
                 int row = view->row();
@@ -523,7 +523,7 @@ void DocumentModel::slotChangeObject(const Gui::ViewProviderDocumentObject& obj,
             // get all occurrences of the view provider in the tree structure
             QList<ViewProviderIndex*> obj_index;
             doc_index->findViewProviders(obj, obj_index);
-            for (const auto & it : obj_index) {
+            for (const auto & it : qAsConst(obj_index)) {
                 QModelIndex parent = createIndex(it->row(),0,it);
                 int count_obj = it->childCount();
                 beginRemoveRows(parent, 0, count_obj);

src/Gui/NotificationArea.cpp

@@ -382,7 +382,7 @@ public:
 
     ~NotificationsAction() override
     {
-        for (auto* item : pushedItems) {
+        for (auto* item : qAsConst(pushedItems)) {
             if (item) {
                 delete item;
             }
@@ -572,7 +572,7 @@ protected:
                 QMenu menu;
 
                 QAction* del = menu.addAction(tr("Delete"), this, [&]() {
-                    for (auto it : selectedItems) {
+                    for (auto it : qAsConst(selectedItems)) {
                         delete it;
                     }
                 });