6 files changed, 36 insertions, 13 deletions

diff --git a/src/plugins/cmakeprojectmanager/cmakeproject.cpp b/src/plugins/cmakeprojectmanager/cmakeproject.cpp
index a1b7b9b946..5a566bffab 100644
--- a/src/plugins/cmakeprojectmanager/cmakeproject.cpp
+++ b/src/plugins/cmakeprojectmanager/cmakeproject.cpp
@@ -134,7 +134,6 @@ CMakeProject::~CMakeProject()
         future.waitForFinished();
     }
     delete m_cppCodeModelUpdater;
-    setRootProjectNode(nullptr);
     qDeleteAll(m_extraCompilers);
     qDeleteAll(m_allFiles);
 }
diff --git a/src/plugins/projectexplorer/project.cpp b/src/plugins/projectexplorer/project.cpp
index 45bf8769da..9eb8956dae 100644
--- a/src/plugins/projectexplorer/project.cpp
+++ b/src/plugins/projectexplorer/project.cpp
@@ -420,13 +420,12 @@ void Project::setDocument(Core::IDocument *doc)
 
 void Project::setRootProjectNode(ProjectNode *root)
 {
-    ProjectNode *oldNode = d->m_rootProjectNode;
-    if (oldNode == root)
+    if (d->m_rootProjectNode == root)
         return;
 
     d->m_rootProjectNode = root;
     emit projectTreeChanged(this, QPrivateSignal());
-    delete oldNode;
+    // Do not delete oldNode! The ProjectTree owns that!
 }
 
 Target *Project::restoreTarget(const QVariantMap &data)
diff --git a/src/plugins/projectexplorer/project.h b/src/plugins/projectexplorer/project.h
index d3dcce9dbf..3ca35707fc 100644
--- a/src/plugins/projectexplorer/project.h
+++ b/src/plugins/projectexplorer/project.h
@@ -51,6 +51,7 @@ class NamedWidget;
 class ProjectImporter;
 class ProjectNode;
 class ProjectPrivate;
+class Session;
 class Target;
 
 // Documentation inside.
@@ -189,6 +190,8 @@ private:
 
     void setActiveTarget(Target *target);
     ProjectPrivate *d;
+
+    friend class Session;
 };
 
 } // namespace ProjectExplorer
diff --git a/src/plugins/projectexplorer/projectnodes.cpp b/src/plugins/projectexplorer/projectnodes.cpp
index 39305c7e8c..ea759cc0eb 100644
--- a/src/plugins/projectexplorer/projectnodes.cpp
+++ b/src/plugins/projectexplorer/projectnodes.cpp
@@ -465,8 +465,6 @@ void FolderNode::buildTree(QList<FileNode *> &files, const Utils::FileName &over
                                                   overrideBaseDir);
         folder->addNode(fn);
     }
-
-    emitTreeChanged();
 }
 
 // "Compress" a tree of foldernodes such that foldernodes with exactly one foldernode as a child
diff --git a/src/plugins/projectexplorer/session.cpp b/src/plugins/projectexplorer/session.cpp
index e977571f88..688439f2f9 100644
--- a/src/plugins/projectexplorer/session.cpp
+++ b/src/plugins/projectexplorer/session.cpp
@@ -188,6 +188,29 @@ void SessionManager::clearProjectFileCache()
         d->m_projectFileCache.clear();
 }
 
+void SessionManager::updateProjectTree(Project *pro)
+{
+    if (!pro)
+        return;
+
+    QPair<Project *, ProjectNode *> *currentPair = nullptr;
+    for (QPair<Project *, ProjectNode *> &pair : d->m_projects) {
+        if (pair.first == pro) {
+            currentPair = &pair;
+            break;
+        }
+    }
+
+    if (!currentPair)
+        return; // Project was already de-registered and is shutting down
+
+    ProjectNode *const oldNode = currentPair->second;
+    ProjectNode *const newNode = pro->rootProjectNode();
+
+    d->m_sessionNode.replaceSubtree(oldNode, newNode);
+    currentPair->second = newNode;
+}
+
 bool SessionManagerPrivate::recursiveDependencyCheck(const QString &newDep, const QString &checkDep) const
 {
     if (newDep == checkDep)
@@ -385,11 +408,11 @@ void SessionManager::addProject(Project *pro)
     d->m_virginSession = false;
     QTC_ASSERT(!hasProject(pro), return);
 
-    d->m_projects.append(qMakePair(pro, pro->rootProjectNode()));
-    d->m_sessionNode.addNode(pro->rootProjectNode());
+    d->m_projects.append(qMakePair(pro, nullptr));
+    m_instance->updateProjectTree(pro);
 
-    connect(pro, &Project::fileListChanged,
-            m_instance, &SessionManager::clearProjectFileCache);
+    connect(pro, &Project::fileListChanged, m_instance, &SessionManager::clearProjectFileCache);
+    connect(pro, &Project::projectTreeChanged, m_instance, &SessionManager::updateProjectTree);
 
     connect(pro, &Project::displayNameChanged, m_instance, [pro] {
         d->m_sessionNode.emitNodeUpdated();
@@ -405,7 +428,7 @@ void SessionManager::removeProject(Project *project)
 {
     d->m_virginSession = false;
     QTC_ASSERT(project, return);
-    removeProjects(QList<Project*>() << project);
+    removeProjects({project});
 }
 
 bool SessionManager::loadingSession()
@@ -737,6 +760,8 @@ void SessionManager::removeProjects(QList<Project *> remove)
     // Delete projects
     foreach (Project *pro, remove) {
         pro->saveSettings();
+        pro->setRootProjectNode(nullptr); // Deregister project with sessionnode!
+
         d->m_projects
                 = Utils::filtered(d->m_projects, [pro](const QPair<Project *, ProjectNode *> &pair)
         {
@@ -749,8 +774,6 @@ void SessionManager::removeProjects(QList<Project *> remove)
         disconnect(pro, &Project::fileListChanged,
                    m_instance, &SessionManager::clearProjectFileCache);
         d->m_projectFileCache.remove(pro);
-
-        d->m_sessionNode.removeNode(pro->rootProjectNode());
         emit m_instance->projectRemoved(pro);
         delete pro;
     }
diff --git a/src/plugins/projectexplorer/session.h b/src/plugins/projectexplorer/session.h
index 1510b7ae5a..b97f297ff2 100644
--- a/src/plugins/projectexplorer/session.h
+++ b/src/plugins/projectexplorer/session.h
@@ -144,6 +144,7 @@ signals: // for tests only
 private:
     static void saveActiveMode(Core::Id mode);
     void clearProjectFileCache();
+    void updateProjectTree(Project *pro);
     static void configureEditor(Core::IEditor *editor, const QString &fileName);
     static void markSessionFileDirty(bool makeDefaultVirginDirty = true);
     static void configureEditors(Project *project);