diff --git a/src/libs/utils/treemodel.cpp b/src/libs/utils/treemodel.cpp
index 22bb5980ba9..5281ab33f5b 100644
--- a/src/libs/utils/treemodel.cpp
+++ b/src/libs/utils/treemodel.cpp
@@ -620,7 +620,13 @@ TreeItem::~TreeItem()
 TreeItem *TreeItem::childAt(int pos) const
 {
     QTC_ASSERT(pos >= 0, return 0);
-    return pos < m_children.size() ? m_children.at(pos) : 0;
+    return pos < childCount() ? *(begin() + pos) : nullptr;
+}
+
+int TreeItem::indexOf(const TreeItem *item) const
+{
+    auto it = std::find(begin(), end(), item);
+    return it == end() ? -1 : it - begin();
 }
 
 QVariant TreeItem::data(int column, int role) const
@@ -661,14 +667,14 @@ void TreeItem::prependChild(TreeItem *item)
 
 void TreeItem::appendChild(TreeItem *item)
 {
-    insertChild(m_children.size(), item);
+    insertChild(childCount(), item);
 }
 
 void TreeItem::insertChild(int pos, TreeItem *item)
 {
     QTC_CHECK(!item->model());
     QTC_CHECK(!item->parent());
-    QTC_ASSERT(0 <= pos && pos <= m_children.size(), return); // '<= size' is intentional.
+    QTC_ASSERT(0 <= pos && pos <= childCount(), return); // '<=' is intentional.
 
     if (m_model) {
         QModelIndex idx = index();
@@ -733,7 +739,7 @@ void TreeItem::updateAll()
     if (m_model) {
         QModelIndex idx = index();
         m_model->dataChanged(idx, idx.sibling(idx.row(), m_model->m_columnCount - 1));
-        foreach (TreeItem *item, m_children)
+        for (TreeItem *item : *this)
             item->updateAll();
     }
 }
@@ -748,12 +754,12 @@ void TreeItem::updateColumn(int column)
 
 TreeItem *TreeItem::firstChild() const
 {
-    return m_children.isEmpty() ? 0 : m_children.first();
+    return childCount() == 0 ? nullptr : *begin();
 }
 
 TreeItem *TreeItem::lastChild() const
 {
-    return m_children.isEmpty() ? 0 : m_children.last();
+    return childCount() == 0 ? nullptr : *(end() - 1);
 }
 
 int TreeItem::level() const
@@ -766,7 +772,7 @@ int TreeItem::level() const
 
 int TreeItem::indexInParent() const
 {
-    return m_parent ? m_parent->m_children.indexOf(const_cast<TreeItem *>(this)) : -1;
+    return m_parent ? m_parent->indexOf(this) : -1;
 }
 
 QModelIndex TreeItem::index() const
@@ -782,7 +788,7 @@ QAbstractItemModel *TreeItem::model() const
 
 void TreeItem::forAllChildren(const std::function<void (TreeItem *)> &pred) const
 {
-    foreach (TreeItem *item, m_children) {
+    for (TreeItem *item : *this) {
         pred(item);
         item->forAllChildren(pred);
     }
@@ -790,7 +796,7 @@ void TreeItem::forAllChildren(const std::function<void (TreeItem *)> &pred) cons
 
 void TreeItem::forSelectedChildren(const std::function<bool (TreeItem *)> &pred) const
 {
-    foreach (TreeItem *item, m_children) {
+    for (TreeItem *item : *this) {
         if (pred(item))
             item->forSelectedChildren(pred);
     }
@@ -800,10 +806,10 @@ void TreeItem::forChildrenAtLevel(int level, const std::function<void(TreeItem *
 {
     QTC_ASSERT(level > 0, return);
     if (level == 1) {
-        foreach (TreeItem *item, m_children)
+        for (TreeItem *item : *this)
             pred(item);
     } else {
-        foreach (TreeItem *item, m_children)
+        for (TreeItem *item : *this)
             item->forChildrenAtLevel(level - 1, pred);
     }
 }
@@ -812,11 +818,11 @@ TreeItem *TreeItem::findChildAtLevel(int level, const std::function<bool(TreeIte
 {
     QTC_ASSERT(level > 0, return 0);
     if (level == 1) {
-        foreach (TreeItem *item, m_children)
+        for (TreeItem *item : *this)
             if (pred(item))
                 return item;
     } else {
-        foreach (TreeItem *item, m_children) {
+        for (TreeItem *item : *this) {
             if (auto found = item->findChildAtLevel(level - 1, pred))
                 return found;
         }
@@ -826,7 +832,7 @@ TreeItem *TreeItem::findChildAtLevel(int level, const std::function<bool(TreeIte
 
 TreeItem *TreeItem::findAnyChild(const std::function<bool(TreeItem *)> &pred) const
 {
-    foreach (TreeItem *item, m_children) {
+    for (TreeItem *item : *this) {
         if (pred(item))
             return item;
         if (TreeItem *found = item->findAnyChild(pred))
@@ -837,7 +843,7 @@ TreeItem *TreeItem::findAnyChild(const std::function<bool(TreeItem *)> &pred) co
 
 void TreeItem::clear()
 {
-    while (m_children.size()) {
+    while (childCount() != 0) {
         TreeItem *item = m_children.takeLast();
         item->m_model = 0;
         item->m_parent = 0;
@@ -857,7 +863,7 @@ void TreeItem::propagateModel(BaseTreeModel *m)
     QTC_ASSERT(m_model == 0 || m_model == m, return);
     if (m && !m_model) {
         m_model = m;
-        foreach (TreeItem *item, m_children)
+        for (TreeItem *item : *this)
             item->propagateModel(m);
     }
 }
@@ -1067,7 +1073,7 @@ QModelIndex BaseTreeModel::indexForItem(const TreeItem *item) const
     QTC_ASSERT(p, return QModelIndex());
 
     TreeItem *mitem = const_cast<TreeItem *>(item);
-    int row = p->m_children.indexOf(mitem);
+    int row = p->indexOf(mitem);
     return createIndex(row, 0, mitem);
 }
 
@@ -1095,7 +1101,7 @@ TreeItem *BaseTreeModel::takeItem(TreeItem *item)
     QTC_ASSERT(item, return item);
     TreeItem *parent = item->parent();
     QTC_ASSERT(parent, return item);
-    int pos = parent->m_children.indexOf(item);
+    int pos = parent->indexOf(item);
     QTC_ASSERT(pos != -1, return item);
 
     QModelIndex idx = indexForItem(parent);
diff --git a/src/libs/utils/treemodel.h b/src/libs/utils/treemodel.h
index ba791c1cf87..8782d7b37df 100644
--- a/src/libs/utils/treemodel.h
+++ b/src/libs/utils/treemodel.h
@@ -64,10 +64,14 @@ public:
     TreeItem *lastChild() const;
     int level() const;
 
-    int childCount() const { return m_children.size(); }
+    using const_iterator = QVector<TreeItem *>::const_iterator;
+    using value_type = TreeItem *;
+    int childCount() const { return end() - begin(); }
     int indexInParent() const;
     TreeItem *childAt(int index) const;
-    QVector<TreeItem *> children() const { return m_children; }
+    int indexOf(const TreeItem *item) const;
+    const_iterator begin() const { return m_children.begin(); }
+    const_iterator end() const { return m_children.end(); }
     QModelIndex index() const;
     QAbstractItemModel *model() const;
 
diff --git a/src/plugins/autotest/testresultmodel.cpp b/src/plugins/autotest/testresultmodel.cpp
index f8fff9fcb3f..6dc6d2a1a54 100644
--- a/src/plugins/autotest/testresultmodel.cpp
+++ b/src/plugins/autotest/testresultmodel.cpp
@@ -104,7 +104,7 @@ void TestResultItem::updateResult()
         return;
 
     Result::Type newResult = Result::MessageTestCaseSuccess;
-    foreach (Utils::TreeItem *child, children()) {
+    for (Utils::TreeItem *child : *this) {
         const TestResult *current = static_cast<TestResultItem *>(child)->testResult();
         if (current) {
             switch (current->result()) {
@@ -131,7 +131,7 @@ void TestResultItem::updateResult()
 
 void TestResultItem::updateIntermediateChildren()
 {
-    for (Utils::TreeItem *child : children()) {
+    for (Utils::TreeItem *child : *this) {
         TestResultItem *childItem = static_cast<TestResultItem *>(child);
         if (childItem->testResult()->result() == Result::MessageIntermediate)
             childItem->updateResult();
@@ -225,9 +225,9 @@ void TestResultModel::addTestResult(const TestResultPtr &testResult, bool autoEx
 
 void TestResultModel::removeCurrentTestMessage()
 {
-    QVector<Utils::TreeItem *> topLevelItems = rootItem()->children();
+    std::vector<Utils::TreeItem *> topLevelItems(rootItem()->begin(), rootItem()->end());
     for (int row = topLevelItems.size() - 1; row >= 0; --row) {
-        TestResultItem *current = static_cast<TestResultItem *>(topLevelItems.at(row));
+        TestResultItem *current = static_cast<TestResultItem *>(topLevelItems[row]);
         if (current->testResult()->result() == Result::MessageCurrentTest) {
             destroyItem(current);
             break;
diff --git a/src/plugins/autotest/testtreemodel.cpp b/src/plugins/autotest/testtreemodel.cpp
index 81f3b6176ae..bace10c474c 100644
--- a/src/plugins/autotest/testtreemodel.cpp
+++ b/src/plugins/autotest/testtreemodel.cpp
@@ -67,7 +67,7 @@ TestTreeModel *TestTreeModel::instance()
 
 TestTreeModel::~TestTreeModel()
 {
-    foreach (Utils::TreeItem *item, rootItem()->children()) {
+    for (Utils::TreeItem *item : *rootItem()) {
         item->removeChildren();
         takeItem(item); // do NOT delete the item as it's still a ptr hold by TestFrameworkManager
     }
@@ -141,7 +141,7 @@ Qt::ItemFlags TestTreeModel::flags(const QModelIndex &index) const
 
 bool TestTreeModel::hasTests() const
 {
-    foreach (Utils::TreeItem *frameworkRoot, rootItem()->children()) {
+    for (Utils::TreeItem *frameworkRoot : *rootItem()) {
         if (frameworkRoot->hasChildren())
             return true;
     }
@@ -151,7 +151,7 @@ bool TestTreeModel::hasTests() const
 QList<TestConfiguration *> TestTreeModel::getAllTestCases() const
 {
     QList<TestConfiguration *> result;
-    foreach (Utils::TreeItem *frameworkRoot, rootItem()->children())
+    for (Utils::TreeItem *frameworkRoot : *rootItem())
         result.append(static_cast<TestTreeItem *>(frameworkRoot)->getAllTestConfigurations());
     return result;
 }
@@ -159,7 +159,7 @@ QList<TestConfiguration *> TestTreeModel::getAllTestCases() const
 QList<TestConfiguration *> TestTreeModel::getSelectedTests() const
 {
     QList<TestConfiguration *> result;
-    foreach (Utils::TreeItem *frameworkRoot, rootItem()->children())
+    for (Utils::TreeItem *frameworkRoot : *rootItem())
         result.append(static_cast<TestTreeItem *>(frameworkRoot)->getSelectedTestConfigurations());
     return result;
 }
@@ -167,7 +167,7 @@ QList<TestConfiguration *> TestTreeModel::getSelectedTests() const
 void TestTreeModel::syncTestFrameworks()
 {
     // remove all currently registered
-    foreach (Utils::TreeItem *item, rootItem()->children()) {
+    for (Utils::TreeItem *item : *rootItem()) {
         item->removeChildren();
         takeItem(item); // do NOT delete the item as it's still a ptr hold by TestFrameworkManager
     }
@@ -190,8 +190,8 @@ void TestTreeModel::removeFiles(const QStringList &files)
 
 void TestTreeModel::markAllForRemoval()
 {
-    foreach (Utils::TreeItem *frameworkRoot, rootItem()->children()) {
-        foreach (Utils::TreeItem *item, frameworkRoot->children())
+    for (Utils::TreeItem *frameworkRoot : *rootItem()) {
+        for (Utils::TreeItem *item : *frameworkRoot)
             static_cast<TestTreeItem *>(item)->markForRemovalRecursively(true);
     }
 }
@@ -201,7 +201,7 @@ void TestTreeModel::markForRemoval(const QString &filePath)
     if (filePath.isEmpty())
         return;
 
-    for (Utils::TreeItem *frameworkRoot : rootItem()->children()) {
+    for (Utils::TreeItem *frameworkRoot : *rootItem()) {
         TestTreeItem *root = static_cast<TestTreeItem *>(frameworkRoot);
         for (int childRow = root->childCount() - 1; childRow >= 0; --childRow) {
             TestTreeItem *child = root->childItem(childRow);
@@ -212,7 +212,7 @@ void TestTreeModel::markForRemoval(const QString &filePath)
 
 void TestTreeModel::sweep()
 {
-    for (Utils::TreeItem *frameworkRoot : rootItem()->children()) {
+    for (Utils::TreeItem *frameworkRoot : *rootItem()) {
         TestTreeItem *root = static_cast<TestTreeItem *>(frameworkRoot);
         sweepChildren(root);
     }
@@ -277,7 +277,7 @@ void TestTreeModel::handleParseResult(const TestParseResult *result, TestTreeIte
 
 void TestTreeModel::removeAllTestItems()
 {
-    foreach (Utils::TreeItem *item, rootItem()->children())
+    for (Utils::TreeItem *item : *rootItem())
         item->removeChildren();
     emit testTreeModelChanged();
 }
@@ -353,9 +353,9 @@ int TestTreeModel::dataTagsCount() const
         return 0;
 
     int dataTagCount = 0;
-    foreach (Utils::TreeItem *item, rootNode->children()) {
+    for (Utils::TreeItem *item : *rootNode) {
         TestTreeItem *classItem = static_cast<TestTreeItem *>(item);
-        foreach (Utils::TreeItem *functionItem, classItem->children())
+        for (Utils::TreeItem *functionItem : *classItem)
             dataTagCount += functionItem->childCount();
    }
     return dataTagCount;
diff --git a/src/plugins/baremetal/gdbserverproviderssettingspage.cpp b/src/plugins/baremetal/gdbserverproviderssettingspage.cpp
index 6cf97c60f08..2e8dc9e4515 100644
--- a/src/plugins/baremetal/gdbserverproviderssettingspage.cpp
+++ b/src/plugins/baremetal/gdbserverproviderssettingspage.cpp
@@ -135,7 +135,7 @@ void GdbServerProviderModel::apply()
     QTC_ASSERT(m_providersToRemove.isEmpty(), m_providersToRemove.clear());
 
     // Update providers
-    foreach (TreeItem *item, rootItem()->children()) {
+    for (TreeItem *item : *rootItem()) {
         auto n = static_cast<GdbServerProviderNode *>(item);
         if (!n->changed)
             continue;
@@ -173,7 +173,7 @@ GdbServerProviderNode *GdbServerProviderModel::findNode(const GdbServerProvider
         return static_cast<GdbServerProviderNode *>(item)->provider == provider;
     };
 
-    return static_cast<GdbServerProviderNode *>(Utils::findOrDefault(rootItem()->children(), test));
+    return static_cast<GdbServerProviderNode *>(Utils::findOrDefault(*rootItem(), test));
 }
 
 QModelIndex GdbServerProviderModel::indexForProvider(GdbServerProvider *provider) const
@@ -209,7 +209,7 @@ GdbServerProviderNode *GdbServerProviderModel::createNode(
     auto n = new GdbServerProviderNode(provider, changed);
     if (n->widget) {
         connect(n->widget, &GdbServerProviderConfigWidget::dirty, this, [this, n] {
-            foreach (TreeItem *item, rootItem()->children()) {
+            for (TreeItem *item : *rootItem()) {
                 auto nn = static_cast<GdbServerProviderNode *>(item);
                 if (nn->widget == n->widget) {
                     nn->changed = true;
diff --git a/src/plugins/clangstaticanalyzer/clangstaticanalyzerdiagnosticmodel.cpp b/src/plugins/clangstaticanalyzer/clangstaticanalyzerdiagnosticmodel.cpp
index 6dd0f72e0e2..a73b4c73e66 100644
--- a/src/plugins/clangstaticanalyzer/clangstaticanalyzerdiagnosticmodel.cpp
+++ b/src/plugins/clangstaticanalyzer/clangstaticanalyzerdiagnosticmodel.cpp
@@ -80,7 +80,7 @@ void ClangStaticAnalyzerDiagnosticModel::addDiagnostics(const QList<Diagnostic>
 QList<Diagnostic> ClangStaticAnalyzerDiagnosticModel::diagnostics() const
 {
     QList<Diagnostic> diags;
-    foreach (const Utils::TreeItem * const item, rootItem()->children())
+    for (const Utils::TreeItem * const item : *rootItem())
         diags << static_cast<const DiagnosticItem *>(item)->diagnostic();
     return diags;
 }
diff --git a/src/plugins/cppeditor/cppincludehierarchy.cpp b/src/plugins/cppeditor/cppincludehierarchy.cpp
index b3b4f6c9f98..9512b2ddcf3 100644
--- a/src/plugins/cppeditor/cppincludehierarchy.cpp
+++ b/src/plugins/cppeditor/cppincludehierarchy.cpp
@@ -200,7 +200,7 @@ QVariant CppIncludeHierarchyItem::data(int column, int role) const
 
 bool CppIncludeHierarchyItem::canFetchMore() const
 {
-    if (m_isCyclic || m_checkedForChildren || !children().isEmpty())
+    if (m_isCyclic || m_checkedForChildren || childCount() > 0)
         return false;
 
     return !model()->m_searching || !model()->m_seen.contains(m_filePath);
diff --git a/src/plugins/debugger/console/consoleitem.cpp b/src/plugins/debugger/console/consoleitem.cpp
index 3b19023a86f..4bf02535947 100644
--- a/src/plugins/debugger/console/consoleitem.cpp
+++ b/src/plugins/debugger/console/consoleitem.cpp
@@ -128,7 +128,7 @@ bool ConsoleItem::setData(int column, const QVariant &data, int role)
 bool ConsoleItem::canFetchMore() const
 {
     // Always fetch all children, too, as the labels depend on them.
-    foreach (TreeItem *child, children()) {
+    for (TreeItem *child : *this) {
         if (static_cast<ConsoleItem *>(child)->m_doFetch)
             return true;
     }
@@ -143,7 +143,7 @@ void ConsoleItem::fetchMore()
         m_doFetch = std::function<void(ConsoleItem *)>();
     }
 
-    foreach (TreeItem *child, children()) {
+    for (TreeItem *child : *this) {
         ConsoleItem *item = static_cast<ConsoleItem *>(child);
         if (item->m_doFetch) {
             item->m_doFetch(item);
diff --git a/src/plugins/debugger/debuggertooltipmanager.cpp b/src/plugins/debugger/debuggertooltipmanager.cpp
index 2d8ce4f83f7..eb60d2df757 100644
--- a/src/plugins/debugger/debuggertooltipmanager.cpp
+++ b/src/plugins/debugger/debuggertooltipmanager.cpp
@@ -221,7 +221,7 @@ ToolTipWatchItem::ToolTipWatchItem(TreeItem *item)
     valueColor = model->data(idx.sibling(idx.row(), 1), Qt::ForegroundRole).value<QColor>();
     expandable = model->hasChildren(idx);
     expression = model->data(idx.sibling(idx.row(), 0), Qt::EditRole).toString();
-    foreach (TreeItem *child, item->children())
+    for (TreeItem *child : *item)
         appendChild(new ToolTipWatchItem(child));
 }
 
diff --git a/src/plugins/debugger/threadshandler.cpp b/src/plugins/debugger/threadshandler.cpp
index 1b4eb9679db..ef32e52df17 100644
--- a/src/plugins/debugger/threadshandler.cpp
+++ b/src/plugins/debugger/threadshandler.cpp
@@ -273,7 +273,7 @@ static ThreadItem *itemForThreadId(const ThreadsHandler *handler, ThreadId threa
 static int indexForThreadId(const ThreadsHandler *handler, ThreadId threadId)
 {
     ThreadItem *item = itemForThreadId(handler, threadId);
-    return item ? handler->rootItem()->children().indexOf(item) : -1;
+    return item ? handler->rootItem()->indexOf(item) : -1;
 }
 
 int ThreadsHandler::currentThreadIndex() const
diff --git a/src/plugins/debugger/watchhandler.cpp b/src/plugins/debugger/watchhandler.cpp
index 69a573eb0ea..30eb019347d 100644
--- a/src/plugins/debugger/watchhandler.cpp
+++ b/src/plugins/debugger/watchhandler.cpp
@@ -970,9 +970,9 @@ QVariant WatchModel::data(const QModelIndex &idx, int role) const
 
     if (role == BaseTreeView::ExtraIndicesForColumnWidth) {
         QModelIndexList l;
-        foreach (TreeItem *item, m_watchRoot->children())
+        for (const TreeItem *item : *m_watchRoot)
             l.append(indexForItem(item));
-        foreach (TreeItem *item, m_returnRoot->children())
+        for (const TreeItem *item : *m_returnRoot)
             l.append(indexForItem(item));
         return QVariant::fromValue(l);
     }
@@ -1237,7 +1237,7 @@ void WatchModel::fetchMore(const QModelIndex &idx)
     WatchItem *item = nonRootItemForIndex(idx);
     if (item) {
         m_expandedINames.insert(item->iname);
-        if (item->children().isEmpty())
+        if (item->childCount() == 0)
             m_engine->expandItem(item->iname);
     }
 }
@@ -1988,10 +1988,10 @@ bool WatchHandler::insertItem(WatchItem *item)
     QTC_ASSERT(parent, return false);
 
     bool found = false;
-    const QVector<TreeItem *> siblings = parent->children();
+    const std::vector<TreeItem *> siblings(parent->begin(), parent->end());
     for (int row = 0, n = siblings.size(); row < n; ++row) {
-        if (static_cast<WatchItem *>(siblings.at(row))->iname == item->iname) {
-            m_model->destroyItem(parent->children().at(row));
+        if (static_cast<WatchItem *>(siblings[row])->iname == item->iname) {
+            m_model->destroyItem(parent->childAt(row));
             parent->insertChild(row, item);
             found = true;
             break;
@@ -2381,7 +2381,7 @@ void WatchHandler::fetchMore(const QString &iname) const
 {
     if (WatchItem *item = m_model->findItem(iname)) {
         m_model->m_expandedINames.insert(iname);
-        if (item->children().isEmpty())
+        if (item->childCount() == 0)
             m_model->m_engine->expandItem(iname);
     }
 }
diff --git a/src/plugins/projectexplorer/kitmodel.cpp b/src/plugins/projectexplorer/kitmodel.cpp
index 8135c8338d0..43205858c9e 100644
--- a/src/plugins/projectexplorer/kitmodel.cpp
+++ b/src/plugins/projectexplorer/kitmodel.cpp
@@ -168,7 +168,7 @@ void KitModel::isAutoDetectedChanged()
 {
     auto w = qobject_cast<KitManagerConfigWidget *>(sender());
     int idx = -1;
-    idx = Utils::indexOf(m_manualRoot->children(), [w](TreeItem *node) {
+    idx = Utils::indexOf(*m_manualRoot, [w](TreeItem *node) {
         return static_cast<KitNode *>(node)->widget == w;
     });
     TreeItem *oldParent = nullptr;
@@ -176,7 +176,7 @@ void KitModel::isAutoDetectedChanged()
     if (idx != -1) {
         oldParent = m_manualRoot;
     } else {
-        idx = Utils::indexOf(m_autoRoot->children(), [w](TreeItem *node) {
+        idx = Utils::indexOf(*m_autoRoot, [w](TreeItem *node) {
             return static_cast<KitNode *>(node)->widget == w;
         });
         if (idx != -1) {
@@ -185,7 +185,7 @@ void KitModel::isAutoDetectedChanged()
     }
 
     if (oldParent && oldParent != newParent) {
-        beginMoveRows(indexForItem(oldParent), idx, idx, indexForItem(newParent), newParent->children().size());
+        beginMoveRows(indexForItem(oldParent), idx, idx, indexForItem(newParent), newParent->childCount());
         TreeItem *n = oldParent->childAt(idx);
         takeItem(n);
         newParent->appendChild(n);
@@ -281,8 +281,7 @@ KitNode *KitModel::createNode(Kit *k)
     auto node = new KitNode(k);
     m_parentLayout->addWidget(node->widget);
     connect(node->widget, &KitManagerConfigWidget::dirty, [this, node] {
-        if (m_autoRoot->children().contains(node)
-                || m_manualRoot->children().contains(node))
+        if (m_autoRoot->indexOf(node) != -1 || m_manualRoot->indexOf(node) != -1)
             node->update();
     });
     connect(node->widget, &KitManagerConfigWidget::isAutoDetectedChanged,
@@ -306,7 +305,7 @@ void KitModel::setDefaultNode(KitNode *node)
 
 void KitModel::addKit(Kit *k)
 {
-    foreach (TreeItem *n, m_manualRoot->children()) {
+    for (TreeItem *n : *m_manualRoot) {
         // Was added by us
         if (static_cast<KitNode *>(n)->widget->configures(k))
             return;
diff --git a/src/plugins/projectexplorer/projectwindow.cpp b/src/plugins/projectexplorer/projectwindow.cpp
index f2d8e4363e1..6077ee7fe83 100644
--- a/src/plugins/projectexplorer/projectwindow.cpp
+++ b/src/plugins/projectexplorer/projectwindow.cpp
@@ -178,7 +178,7 @@ public:
         if (role == ItemActivatedFromBelowRole) {
             TreeItem *item = data.value<TreeItem *>();
             QTC_ASSERT(item, return false);
-            m_currentPanelIndex = children().indexOf(item);
+            m_currentPanelIndex = indexOf(item);
             QTC_ASSERT(m_currentPanelIndex != -1, return false);
             parent()->setData(0, QVariant::fromValue(static_cast<TreeItem *>(this)),
                               ItemActivatedFromBelowRole);
@@ -251,9 +251,9 @@ public:
         }
 
         if (role == ItemActivatedFromBelowRole) {
-            TreeItem *item = dat.value<TreeItem *>();
+            const TreeItem *item = dat.value<TreeItem *>();
             QTC_ASSERT(item, return false);
-            int res = children().indexOf(item);
+            int res = indexOf(item);
             QTC_ASSERT(res >= 0, return false);
             m_currentChildIndex = res;
             announceChange();
diff --git a/src/plugins/projectexplorer/targetsettingspanel.cpp b/src/plugins/projectexplorer/targetsettingspanel.cpp
index f7ccbf62e8f..65780a6d35b 100644
--- a/src/plugins/projectexplorer/targetsettingspanel.cpp
+++ b/src/plugins/projectexplorer/targetsettingspanel.cpp
@@ -386,7 +386,7 @@ public:
 
         if (role == ItemActivatedFromBelowRole) {
             // I.e. 'Build' and 'Run' items were present and user clicked on them.
-            int child = children().indexOf(data.value<TreeItem *>());
+            int child = indexOf(data.value<TreeItem *>());
             QTC_ASSERT(child != -1, return false);
             m_currentChild = child; // Triggered from sub-item.
             SessionManager::setActiveTarget(m_project, target(), SetActive::Cascade);
@@ -788,7 +788,7 @@ void TargetGroupItemPrivate::handleAddedKit(Kit *kit)
 
 void TargetItem::updateSubItems()
 {
-    if (children().isEmpty() && isEnabled())
+    if (childCount() == 0 && isEnabled())
         m_currentChild = DefaultPage; // We will add children below.
     removeChildren();
     if (isEnabled()) {
diff --git a/src/plugins/projectexplorer/toolchainoptionspage.cpp b/src/plugins/projectexplorer/toolchainoptionspage.cpp
index 411c95a802d..ba159fc7374 100644
--- a/src/plugins/projectexplorer/toolchainoptionspage.cpp
+++ b/src/plugins/projectexplorer/toolchainoptionspage.cpp
@@ -330,7 +330,7 @@ void ToolChainOptionsWidget::apply()
     // Update tool chains:
     foreach (const Core::Id &l, m_languageMap.keys()) {
         StaticTreeItem *parent = m_languageMap.value(l).second;
-        foreach (TreeItem *item, parent->children()) {
+        for (TreeItem *item : *parent) {
             auto tcItem = static_cast<ToolChainTreeItem *>(item);
             Q_ASSERT(tcItem->toolChain);
             if (tcItem->widget)
diff --git a/src/plugins/qtsupport/qtoptionspage.cpp b/src/plugins/qtsupport/qtoptionspage.cpp
index 69db72a15a9..23e10b9a17a 100644
--- a/src/plugins/qtsupport/qtoptionspage.cpp
+++ b/src/plugins/qtsupport/qtoptionspage.cpp
@@ -298,7 +298,7 @@ void QtOptionsPageWidget::cleanUpQtVersions()
     QVector<QtVersionItem *> toRemove;
     QString text;
 
-    foreach (Utils::TreeItem *child, m_manualItem->children()) {
+    for (TreeItem *child : *m_manualItem) {
         auto item = static_cast<QtVersionItem *>(child);
         if (item->version() && !item->version()->isValid()) {
             toRemove.append(item);
@@ -672,7 +672,7 @@ void QtOptionsPageWidget::editPath()
 void QtOptionsPageWidget::updateCleanUpButton()
 {
     bool hasInvalidVersion = false;
-    foreach (Utils::TreeItem *child, m_manualItem->children()) {
+    for (TreeItem *child : *m_manualItem) {
         auto item = static_cast<QtVersionItem *>(child);
         if (item->version() && !item->version()->isValid()) {
             hasInvalidVersion = true;