diff --git a/src/plugins/projectexplorer/nodesvisitor.cpp b/src/plugins/projectexplorer/nodesvisitor.cpp
index ed33ef13697..d432d664488 100644
--- a/src/plugins/projectexplorer/nodesvisitor.cpp
+++ b/src/plugins/projectexplorer/nodesvisitor.cpp
@@ -81,11 +81,6 @@ QList<Node*> FindNodesForFileVisitor::nodes() const
     return m_nodes;
 }
 
-void FindNodesForFileVisitor::visitProjectNode(ProjectNode *node)
-{
-    visitFolderNode(node);
-}
-
 void FindNodesForFileVisitor::visitFolderNode(FolderNode *node)
 {
     if (node->filePath() == m_path)
@@ -96,11 +91,6 @@ void FindNodesForFileVisitor::visitFolderNode(FolderNode *node)
     }
 }
 
-void FindNodesForFileVisitor::visitSessionNode(SessionNode *node)
-{
-    visitFolderNode(node);
-}
-
 /*!
   \class FindAllFilesVisitor
 
@@ -112,11 +102,6 @@ Utils::FileNameList FindAllFilesVisitor::filePaths() const
     return m_filePaths;
 }
 
-void FindAllFilesVisitor::visitProjectNode(ProjectNode *projectNode)
-{
-    visitFolderNode(projectNode);
-}
-
 void FindAllFilesVisitor::visitFolderNode(FolderNode *folderNode)
 {
     m_filePaths.append(folderNode->filePath());
diff --git a/src/plugins/projectexplorer/nodesvisitor.h b/src/plugins/projectexplorer/nodesvisitor.h
index 641be9025ab..d57f498589d 100644
--- a/src/plugins/projectexplorer/nodesvisitor.h
+++ b/src/plugins/projectexplorer/nodesvisitor.h
@@ -36,15 +36,13 @@ namespace ProjectExplorer {
 class Node;
 class FileNode;
 class SessionNode;
-class ProjectNode;
 class FolderNode;
 
-class PROJECTEXPLORER_EXPORT NodesVisitor {
+class PROJECTEXPLORER_EXPORT NodesVisitor
+{
 public:
     virtual ~NodesVisitor();
 
-    virtual void visitSessionNode(SessionNode *) { }
-    virtual void visitProjectNode(ProjectNode *) { }
     virtual void visitFolderNode(FolderNode *) { }
 
 protected:
@@ -53,26 +51,25 @@ protected:
 
 /* useful visitors */
 
-class PROJECTEXPLORER_EXPORT FindNodesForFileVisitor : public NodesVisitor {
+class PROJECTEXPLORER_EXPORT FindNodesForFileVisitor : public NodesVisitor
+{
 public:
     explicit FindNodesForFileVisitor(const Utils::FileName &fileToSearch);
 
     QList<Node*> nodes() const;
 
-    void visitProjectNode(ProjectNode *node) override;
     void visitFolderNode(FolderNode *node) override;
-    void visitSessionNode(SessionNode *node) override;
 
 private:
     Utils::FileName m_path;
     QList<Node *> m_nodes;
 };
 
-class PROJECTEXPLORER_EXPORT FindAllFilesVisitor : public NodesVisitor {
+class PROJECTEXPLORER_EXPORT FindAllFilesVisitor : public NodesVisitor
+{
 public:
     Utils::FileNameList filePaths() const;
 
-    void visitProjectNode(ProjectNode *projectNode) override;
     void visitFolderNode(FolderNode *folderNode) override;
 
 private:
diff --git a/src/plugins/projectexplorer/projectnodes.cpp b/src/plugins/projectexplorer/projectnodes.cpp
index 9ec6f7ba273..586d88d19e9 100644
--- a/src/plugins/projectexplorer/projectnodes.cpp
+++ b/src/plugins/projectexplorer/projectnodes.cpp
@@ -686,24 +686,24 @@ QList<RunConfiguration *> ProjectNode::runConfigurations() const
     return QList<RunConfiguration *>();
 }
 
-void ProjectNode::accept(NodesVisitor *visitor)
-{
-    visitor->visitProjectNode(this);
-
-    foreach (FolderNode *folder, m_folderNodes)
-        folder->accept(visitor);
-}
-
 ProjectNode *ProjectNode::projectNode(const Utils::FileName &file) const
 {
-    return Utils::findOrDefault(m_projectNodes, [&file](const ProjectNode *fn) {
-        return fn->filePath() == file;
-    });
+    for (FolderNode *node : m_folderNodes) {
+        if (ProjectNode *pnode = node->asProjectNode())
+            if (pnode->filePath() == file)
+                return pnode;
+    }
+    return nullptr;
 }
 
-QList<ProjectNode*> ProjectNode::projectNodes() const
+QList<ProjectNode*> FolderNode::projectNodes() const
 {
-    return m_projectNodes;
+    QList<ProjectNode *> nodes;
+    for (FolderNode *node : m_folderNodes) {
+        if (ProjectNode *pnode = node->asProjectNode())
+            nodes.append(pnode);
+    }
+    return nodes;
 }
 
 /*!
@@ -717,31 +717,13 @@ void ProjectNode::addProjectNode(ProjectNode *subProject)
 
     subProject->setParentFolderNode(this);
     m_folderNodes.append(subProject);
-    m_projectNodes.append(subProject);
 
     Utils::sort(m_folderNodes);
-    Utils::sort(m_projectNodes);
 }
 
-
-/*!
-  Removes all child nodes from the node hierarchy and deletes them.
-*/
-
-void ProjectNode::makeEmpty()
+bool FolderNode::isEmpty() const
 {
-    foreach (ProjectNode *subProject, m_projectNodes)
-        m_folderNodes.removeAll(subProject);
-
-    qDeleteAll(m_projectNodes);
-    m_projectNodes.clear();
-
-    FolderNode::makeEmpty();
-}
-
-bool ProjectNode::isEmpty() const
-{
-    return m_fileNodes.isEmpty() && m_folderNodes.isEmpty() && m_projectNodes.isEmpty();
+    return m_fileNodes.isEmpty() && m_folderNodes.isEmpty();
 }
 
 /*!
@@ -758,24 +740,11 @@ QList<ProjectAction> SessionNode::supportedActions(Node *node) const
     return QList<ProjectAction>();
 }
 
-
-void SessionNode::accept(NodesVisitor *visitor)
-{
-    visitor->visitSessionNode(this);
-    foreach (ProjectNode *project, m_projectNodes)
-        project->accept(visitor);
-}
-
 bool SessionNode::showInSimpleTree() const
 {
     return true;
 }
 
-QList<ProjectNode*> SessionNode::projectNodes() const
-{
-    return m_projectNodes;
-}
-
 QString SessionNode::addFileFilter() const
 {
     return QString::fromLatin1("*.c; *.cc; *.cpp; *.cp; *.cxx; *.c++; *.h; *.hh; *.hpp; *.hxx;");
@@ -787,16 +756,12 @@ void SessionNode::addProjectNode(ProjectNode *projectNode)
                qDebug("Project node has already a parent folder"));
     projectNode->setParentFolderNode(this);
     m_folderNodes.append(projectNode);
-    m_projectNodes.append(projectNode);
-
     Utils::sort(m_folderNodes);
-    Utils::sort(m_projectNodes);
 }
 
 void SessionNode::removeProjectNode(ProjectNode *projectNode)
 {
     m_folderNodes.removeOne(projectNode);
-    m_projectNodes.removeOne(projectNode);
 }
 
 } // namespace ProjectExplorer
diff --git a/src/plugins/projectexplorer/projectnodes.h b/src/plugins/projectexplorer/projectnodes.h
index 16f6701b815..d440ea7ed00 100644
--- a/src/plugins/projectexplorer/projectnodes.h
+++ b/src/plugins/projectexplorer/projectnodes.h
@@ -251,6 +251,9 @@ public:
     void addFolderNode(FolderNode *subFolder);
     void setFolderNodes(const QList<FolderNode*> &folders);
 
+    // all subFolders that are projects
+    QList<ProjectNode*> projectNodes() const;
+
     void makeEmpty();
     bool isEmpty() const;
 
@@ -296,16 +299,8 @@ public:
 
     virtual QList<RunConfiguration *> runConfigurations() const;
 
-    void accept(NodesVisitor *visitor) override;
-
     ProjectNode *projectNode(const Utils::FileName &file) const;
-    // all subFolders that are projects
-    QList<ProjectNode*> projectNodes() const;
     void addProjectNode(ProjectNode *subProject);
-    void removeProjectNode(ProjectNode *subProject);
-
-    void makeEmpty();
-    bool isEmpty() const;
 
     ProjectNode *asProjectNode() final { return this; }
     const ProjectNode *asProjectNode() const final { return this; }
@@ -316,8 +311,6 @@ protected:
     explicit ProjectNode(const Utils::FileName &projectFilePath);
 
 private:
-    QList<ProjectNode*> m_projectNodes;
-
     // let SessionNode call setParentFolderNode
     friend class SessionNode;
 };
@@ -327,12 +320,10 @@ class PROJECTEXPLORER_EXPORT SessionNode : public FolderNode
 {
 public:
     SessionNode();
-    QList<ProjectNode*> projectNodes() const;
 
 private:
     QList<ProjectAction> supportedActions(Node *node) const final;
     QString addFileFilter() const final;
-    void accept(NodesVisitor *visitor) final;
 
     bool showInSimpleTree() const final;
     void projectDisplayNameChanged(Node *node);
@@ -343,8 +334,6 @@ private:
     friend class SessionManager;
     void addProjectNode(ProjectNode *projectNode);
     void removeProjectNode(ProjectNode *projectNode);
-
-    QList<ProjectNode*> m_projectNodes;
 };
 
 } // namespace ProjectExplorer
diff --git a/src/plugins/qmakeprojectmanager/findqmakeprofiles.cpp b/src/plugins/qmakeprojectmanager/findqmakeprofiles.cpp
index 29f8f34b87e..c0f3a5e9cbb 100644
--- a/src/plugins/qmakeprojectmanager/findqmakeprofiles.cpp
+++ b/src/plugins/qmakeprojectmanager/findqmakeprofiles.cpp
@@ -36,8 +36,8 @@ QList<QmakeProFileNode *> FindQmakeProFiles::operator()(ProjectExplorer::Project
     return m_proFiles;
 }
 
-void FindQmakeProFiles::visitProjectNode(ProjectExplorer::ProjectNode *projectNode)
+void FindQmakeProFiles::visitFolderNode(ProjectExplorer::FolderNode *folderNode)
 {
-    if (QmakeProFileNode *pro = dynamic_cast<QmakeProFileNode *>(projectNode))
+    if (QmakeProFileNode *pro = dynamic_cast<QmakeProFileNode *>(folderNode))
         m_proFiles.append(pro);
 }
diff --git a/src/plugins/qmakeprojectmanager/findqmakeprofiles.h b/src/plugins/qmakeprojectmanager/findqmakeprofiles.h
index ba1772c78c6..4a19267b4d0 100644
--- a/src/plugins/qmakeprojectmanager/findqmakeprofiles.h
+++ b/src/plugins/qmakeprojectmanager/findqmakeprofiles.h
@@ -27,6 +27,8 @@
 
 #include <projectexplorer/nodesvisitor.h>
 
+namespace ProjectExplorer { class ProjectNode; }
+
 namespace QmakeProjectManager {
 class QmakeProFileNode;
 namespace Internal {
@@ -36,7 +38,7 @@ class FindQmakeProFiles: protected ProjectExplorer::NodesVisitor
 public:
     QList<QmakeProFileNode *> operator()(ProjectExplorer::ProjectNode *root);
 protected:
-    virtual void visitProjectNode(ProjectExplorer::ProjectNode *projectNode);
+    void visitFolderNode(ProjectExplorer::FolderNode *folderNode) final;
 private:
     QList<QmakeProFileNode *> m_proFiles;
 };
diff --git a/src/plugins/qmakeprojectmanager/qmakenodes.cpp b/src/plugins/qmakeprojectmanager/qmakenodes.cpp
index 30dcf659461..c86ae7496a8 100644
--- a/src/plugins/qmakeprojectmanager/qmakenodes.cpp
+++ b/src/plugins/qmakeprojectmanager/qmakenodes.cpp
@@ -1391,18 +1391,15 @@ static QmakeProjectType proFileTemplateTypeToProjectType(ProFileEvaluator::Templ
 
 namespace {
     // feed all files accepted by any of the factories to the callback.
-    class FindGeneratorSourcesVisitor : public NodesVisitor {
+    class FindGeneratorSourcesVisitor : public NodesVisitor
+    {
     public:
         FindGeneratorSourcesVisitor(
                 const QList<ProjectExplorer::ExtraCompilerFactory *> &factories,
                 std::function<void(FileNode *, ProjectExplorer::ExtraCompilerFactory *)> callback) :
             factories(factories), callback(callback) {}
 
-        void visitProjectNode(ProjectNode *projectNode)
-        {
-            visitFolderNode(projectNode);
-        }
-        void visitFolderNode(FolderNode *folderNode)
+        void visitFolderNode(FolderNode *folderNode) final
         {
             foreach (FileNode *fileNode, folderNode->fileNodes()) {
                 foreach (ProjectExplorer::ExtraCompilerFactory *factory, factories) {
diff --git a/src/plugins/qmakeprojectmanager/qmakeproject.cpp b/src/plugins/qmakeprojectmanager/qmakeproject.cpp
index 490c06157b4..85bf9e64c98 100644
--- a/src/plugins/qmakeprojectmanager/qmakeproject.cpp
+++ b/src/plugins/qmakeprojectmanager/qmakeproject.cpp
@@ -161,11 +161,9 @@ class ProjectFilesVisitor : public NodesVisitor
     ProjectFilesVisitor(QmakeProjectFiles *files);
 
 public:
-
     static void findProjectFiles(QmakeProFileNode *rootNode, QmakeProjectFiles *files);
 
-    void visitProjectNode(ProjectNode *projectNode);
-    void visitFolderNode(FolderNode *folderNode);
+    void visitFolderNode(FolderNode *folderNode) final;
 
 private:
     QmakeProjectFiles *m_files;
@@ -199,14 +197,10 @@ void ProjectFilesVisitor::findProjectFiles(QmakeProFileNode *rootNode, QmakeProj
     unique(files->proFiles);
 }
 
-void ProjectFilesVisitor::visitProjectNode(ProjectNode *projectNode)
-{
-    m_files->proFiles.append(projectNode->filePath().toString());
-    visitFolderNode(projectNode);
-}
-
 void ProjectFilesVisitor::visitFolderNode(FolderNode *folderNode)
 {
+    if (ProjectNode *projectNode = folderNode->asProjectNode())
+        m_files->proFiles.append(projectNode->filePath().toString());
     if (dynamic_cast<ResourceEditor::ResourceTopLevelNode *>(folderNode))
         m_files->files[static_cast<int>(FileType::Resource)].push_back(folderNode->filePath().toString());