update theOnlyProject field after project dispose because otherwise "projectDisposed" listeners from the other project might get the wrong project to fix IDEA-209724 Smart pointer creation during project disposal leads to "Element from alien project" assertion

platform/platform-impl/src/com/intellij/openapi/project/impl/DefaultProject.java

@@ -3,7 +3,6 @@ package com.intellij.openapi.project.impl;
 
 import com.intellij.openapi.components.ComponentConfig;
 import com.intellij.openapi.diagnostic.Logger;
-import com.intellij.openapi.project.ProjectManager;
 import org.jetbrains.annotations.NotNull;
 import org.jetbrains.annotations.Nullable;
 
@@ -51,6 +50,5 @@ final class DefaultProject extends ProjectImpl {
     if (LOG.isDebugEnabled()) {
       LOG.debug("Disposed DefaultProject "+this);
     }
-    ((ProjectManagerImpl)ProjectManager.getInstance()).updateTheOnlyProjectField();
   }
 }

platform/platform-impl/src/com/intellij/openapi/project/impl/DefaultProjectTimed.java

@@ -40,7 +40,7 @@ public class DefaultProjectTimed extends TimedReference<Project> {
 
   @NotNull
   @Override
-  public synchronized Project get() {
+  public Project get() {
     Project value = super.get();
     if (value == null) {
       value = compute();
@@ -50,7 +50,7 @@ public class DefaultProjectTimed extends TimedReference<Project> {
   }
 
   @Override
-  public synchronized void dispose() {
+  public void dispose() {
     // project must be disposed in EDT in write action
     Runnable doDispose = () -> WriteCommandAction.runWriteCommandAction(null, () -> super.dispose());
     if (ApplicationManager.getApplication().isDispatchThread()) {

platform/platform-impl/src/com/intellij/openapi/project/impl/ProjectImpl.java

@@ -29,6 +29,7 @@ import com.intellij.openapi.progress.ProgressIndicatorProvider;
 import com.intellij.openapi.progress.ProgressManager;
 import com.intellij.openapi.project.DumbAwareRunnable;
 import com.intellij.openapi.project.Project;
+import com.intellij.openapi.project.ProjectManager;
 import com.intellij.openapi.project.ex.ProjectEx;
 import com.intellij.openapi.project.ex.ProjectManagerEx;
 import com.intellij.openapi.startup.StartupManager;
@@ -347,6 +348,8 @@ public class ProjectImpl extends PlatformComponentManagerImpl implements Project
     if (!application.isDisposed()) {
       application.getMessageBus().syncPublisher(ProjectLifecycleListener.TOPIC).afterProjectClosed(this);
     }
+    ((ProjectManagerImpl)ProjectManager.getInstance()).updateTheOnlyProjectField();
+
     TimedReference.disposeTimed();
     LaterInvocator.purgeExpiredItems();
   }

platform/platform-impl/src/com/intellij/openapi/project/impl/ProjectManagerImpl.java

@@ -328,19 +328,23 @@ public class ProjectManagerImpl extends ProjectManagerEx implements Disposable {
 
   @Override
   @TestOnly
-  public synchronized boolean isDefaultProjectInitialized() {
-    return myDefaultProjectTimed.isCached();
+  public boolean isDefaultProjectInitialized() {
+    synchronized (lock) {
+      return myDefaultProjectTimed.isCached();
+    }
   }
 
   @Override
   @NotNull
-  public synchronized Project getDefaultProject() {
-    LOG.assertTrue(!ApplicationManager.getApplication().isDisposed(), "Default project has been already disposed!");
-    Project defaultProject = myDefaultProjectTimed.get();
-    // disable "the only project" optimization since we have now more than one project.
-    // (even though the default project is not a real project, it can be used indirectly in e.g. "Settings|Code Style" code fragments PSI)
-    updateTheOnlyProjectField();
-    return defaultProject;
+  public Project getDefaultProject() {
+    synchronized (lock) {
+      LOG.assertTrue(!ApplicationManager.getApplication().isDisposed(), "Default project has been already disposed!");
+      Project defaultProject = myDefaultProjectTimed.get();
+      // disable "the only project" optimization since we have now more than one project.
+      // (even though the default project is not a real project, it can be used indirectly in e.g. "Settings|Code Style" code fragments PSI)
+      updateTheOnlyProjectField();
+      return defaultProject;
+    }
   }
 
   @Override
@@ -459,7 +463,6 @@ public class ProjectManagerImpl extends ProjectManagerEx implements Disposable {
   private void removeFromOpened(@NotNull Project project) {
     synchronized (lock) {
       myOpenProjects = ArrayUtil.remove(myOpenProjects, project);
-      updateTheOnlyProjectField();
       myOpenProjectByHash.values().remove(project); // remove by value and not by key!
     }
   }