platform tests:

register fake EP for virtualfilemanager for avoiding coping listeners to the new area

We have to it because virtualfilemanagerimpl has non-static KeyedExtensionCollector and the listener is registered every time when the virtualfilemanagerimpl instance is created

+ minor: avoid non-static and non-final KeyedExtensionCollector in other places

platform/core-impl/src/com/intellij/core/CoreApplicationEnvironment.java

@@ -51,6 +51,7 @@ import com.intellij.psi.meta.MetaDataRegistrar;
 import com.intellij.psi.stubs.CoreStubTreeLoader;
 import com.intellij.psi.stubs.StubTreeLoader;
 import com.intellij.util.Consumer;
+import com.intellij.util.KeyedLazyInstanceEP;
 import com.intellij.util.Processor;
 import com.intellij.util.graph.GraphAlgorithms;
 import com.intellij.util.graph.impl.GraphAlgorithmsImpl;
@@ -105,6 +106,9 @@ public class CoreApplicationEnvironment {
                              : new VirtualFileSystem[]{myLocalFileSystem, myJarFileSystem};
     VirtualFileManagerImpl virtualFileManager = new VirtualFileManagerImpl(fs, myApplication.getMessageBus());
     registerComponentInstance(appContainer, VirtualFileManager.class, virtualFileManager);
+    
+    //fake EP for cleaning resources after area disposing (otherwise KeyedExtensionCollector listener will be copied to the next area) 
+    registerApplicationExtensionPoint(new ExtensionPointName<>("com.intellij.virtualFileSystem"), KeyedLazyInstanceEP.class);
 
     registerApplicationService(EncodingManager.class, new CoreEncodingRegistry());
     registerApplicationService(VirtualFilePointerManager.class, createVirtualFilePointerManager());

platform/extensions/src/com/intellij/openapi/extensions/impl/ExtensionsAreaImpl.java

@@ -66,25 +66,24 @@ public class ExtensionsAreaImpl implements ExtensionsArea {
     }
     //this code is required because we have a lot of static extensions e.g. LanguageExtension that are initialized only once
     //for the extensions AvailabilityListeners will be broken if the initialization happened in "fake" area which doesn't have required EP
-    //commented because of memory leak in VirtualFileManagerImpl in kotlin 
-    //if (myAvailabilityListeners.size() > 0) {
-    //  for (Map.Entry<String, Collection<ExtensionPointAvailabilityListener>> entry : myAvailabilityListeners.entrySet()) {
-    //    String key = entry.getKey();
-    //    if (!processedEPs.contains(key)) {
-    //      boolean wasAdded = false;
-    //      //if listeners are "detached" for any EP we have to transfer them to the new area (otherwise it will affect area searching)
-    //      for (ExtensionPointAvailabilityListener listener : entry.getValue()) {
-    //        if (!newArea.hasAvailabilityListener(key, listener)) {
-    //          newArea.addAvailabilityListener(key, listener);
-    //          wasAdded = true;
-    //        }
-    //      }
-    //      if (wasAdded) {
-    //        processedEPs.add(key);
-    //      }
-    //    }
-    //  }
-    //}
+    if (myAvailabilityListeners.size() > 0) {
+      for (Map.Entry<String, Collection<ExtensionPointAvailabilityListener>> entry : myAvailabilityListeners.entrySet()) {
+        String key = entry.getKey();
+        if (!processedEPs.contains(key)) {
+          boolean wasAdded = false;
+          //if listeners are "detached" for any EP we have to transfer them to the new area (otherwise it will affect area searching)
+          for (ExtensionPointAvailabilityListener listener : entry.getValue()) {
+            if (!newArea.hasAvailabilityListener(key, listener)) {
+              newArea.addAvailabilityListener(key, listener);
+              wasAdded = true;
+            }
+          }
+          if (wasAdded) {
+            processedEPs.add(key);
+          }
+        }
+      }
+    }
 
     for (ExtensionPointImpl point : newArea.myExtensionPoints.values()) {
       if (!processedEPs.contains(point.getName())) {

platform/lang-api/src/com/intellij/codeInsight/daemon/LineMarkerProviders.java

@@ -24,7 +24,7 @@ import org.jetbrains.annotations.NonNls;
  * @author Konstantin Bulenkov
  */
 public class LineMarkerProviders extends LanguageExtension<LineMarkerProvider> {
-  public static LineMarkerProviders INSTANCE = new LineMarkerProviders();
+  public static final LineMarkerProviders INSTANCE = new LineMarkerProviders();
   @NonNls public static final String EP_NAME = "com.intellij.codeInsight.lineMarkerProvider";
 
   private LineMarkerProviders() {

platform/lang-impl/src/com/intellij/codeInsight/TargetElementUtil.java

@@ -450,7 +450,7 @@ public class TargetElementUtil extends TargetElementUtilBase {
     return PsiSearchHelper.SERVICE.getInstance(element.getProject()).getUseScope(file != null ? file : element);
   }
 
-  protected final LanguageExtension<TargetElementEvaluator> targetElementEvaluator =
+  protected static final LanguageExtension<TargetElementEvaluator> targetElementEvaluator =
     new LanguageExtension<>("com.intellij.targetElementEvaluator");
   @Nullable
   private TargetElementEvaluatorEx getElementEvaluatorsEx(@NotNull Language language) {

platform/lang-impl/src/com/intellij/codeInsight/editorActions/CodeBlockProviders.java

@@ -21,7 +21,7 @@ import com.intellij.lang.LanguageExtension;
  * @author yole
  */
 public class CodeBlockProviders extends LanguageExtension<CodeBlockProvider> {
-  public static CodeBlockProviders INSTANCE = new CodeBlockProviders();
+  public static final CodeBlockProviders INSTANCE = new CodeBlockProviders();
   
   private CodeBlockProviders() {
     super("com.intellij.codeBlockProvider");