WritableScope.changeLockLevel()

There are thress lock levels: reading, writing, both. Scope modification
is not allowed in "reading" and scope data access is not allowed in "writing".

compiler/frontend/src/org/jetbrains/jet/lang/descriptors/FunctionDescriptorUtil.java

@@ -80,6 +80,7 @@ public class FunctionDescriptorUtil {
             parameterScope.addVariableDescriptor(valueParameterDescriptor);
         }
         parameterScope.addLabeledDeclaration(descriptor);
+        parameterScope.changeLockLevel(WritableScope.LockLevel.READING);
         return parameterScope;
     }
 

compiler/frontend/src/org/jetbrains/jet/lang/descriptors/MutableClassDescriptor.java

@@ -49,8 +49,11 @@ public class MutableClassDescriptor extends MutableDeclarationDescriptor impleme
         super(containingDeclaration);
         TraceBasedRedeclarationHandler redeclarationHandler = new TraceBasedRedeclarationHandler(trace);
         this.scopeForMemberLookup = new WritableScopeImpl(JetScope.EMPTY, this, redeclarationHandler).setDebugName("MemberLookup");
+        this.scopeForMemberLookup.changeLockLevel(WritableScope.LockLevel.BOTH);
         this.scopeForSupertypeResolution = new WritableScopeImpl(outerScope, this, redeclarationHandler).setDebugName("SupertypeResolution");
+        this.scopeForSupertypeResolution.changeLockLevel(WritableScope.LockLevel.BOTH);
         this.scopeForMemberResolution = new WritableScopeImpl(scopeForSupertypeResolution, this, redeclarationHandler).setDebugName("MemberResolution");
+        this.scopeForMemberResolution.changeLockLevel(WritableScope.LockLevel.BOTH);
         this.kind = kind;
     }
 
@@ -180,6 +183,7 @@ public class MutableClassDescriptor extends MutableDeclarationDescriptor impleme
             this.typeParameters.add(typeParameterDescriptor);
             scopeForSupertypeResolution.addTypeParameterDescriptor(typeParameterDescriptor);
         }
+        scopeForSupertypeResolution.changeLockLevel(WritableScope.LockLevel.READING);
     }
 
     ////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
@@ -344,4 +348,13 @@ public class MutableClassDescriptor extends MutableDeclarationDescriptor impleme
         }
         return implicitReceiver;
     }
+    
+    public void lockScopes() {
+        scopeForSupertypeResolution.changeLockLevel(WritableScope.LockLevel.READING);
+        scopeForMemberLookup.changeLockLevel(WritableScope.LockLevel.READING);
+        scopeForMemberResolution.changeLockLevel(WritableScope.LockLevel.READING);
+        if (classObjectDescriptor != null) {
+            classObjectDescriptor.lockScopes();
+        }
+    }
 }

compiler/frontend/src/org/jetbrains/jet/lang/resolve/AnalyzingUtils.java

@@ -96,6 +96,7 @@ public class AnalyzingUtils {
         final WritableScope scope = new WritableScopeImpl(JetScope.EMPTY, owner, new TraceBasedRedeclarationHandler(bindingTraceContext)).setDebugName("Root scope in analyzeNamespace");
         importingStrategy.addImports(project, semanticServices, bindingTraceContext, scope);
         scope.importScope(libraryScope);
+        scope.changeLockLevel(WritableScope.LockLevel.BOTH);
 
         TopDownAnalyzer.process(semanticServices, bindingTraceContext, scope, new NamespaceLike.Adapter(owner) {
 

compiler/frontend/src/org/jetbrains/jet/lang/resolve/BodyResolver.java

@@ -383,6 +383,8 @@ public class BodyResolver {
 
         constructorScope.addLabeledDeclaration(descriptor); // TODO : Labels for constructors?!
         
+        constructorScope.changeLockLevel(WritableScope.LockLevel.READING);
+
         return constructorScope;
     }
 
@@ -442,6 +444,7 @@ public class BodyResolver {
         if (receiver.exists()) {
             result.setImplicitReceiver(receiver);
         }
+        result.changeLockLevel(WritableScope.LockLevel.READING);
         return result;
     }
 
@@ -450,6 +453,7 @@ public class BodyResolver {
 
         WritableScope accessorScope = new WritableScopeImpl(getPropertyDeclarationInnerScope(declaringScope, propertyDescriptor), declaringScope.getContainingDeclaration(), new TraceBasedRedeclarationHandler(context.getTrace())).setDebugName("Accessor scope");
         accessorScope.addPropertyDescriptorByFieldName("$" + propertyDescriptor.getName(), propertyDescriptor);
+        accessorScope.changeLockLevel(WritableScope.LockLevel.READING);
 
         JetPropertyAccessor getter = property.getGetter();
         PropertyGetterDescriptor getterDescriptor = propertyDescriptor.getGetter();

compiler/frontend/src/org/jetbrains/jet/lang/resolve/DescriptorResolver.java

@@ -146,6 +146,7 @@ public class DescriptorResolver {
         innerScope.addLabeledDeclaration(functionDescriptor);
 
         List<TypeParameterDescriptor> typeParameterDescriptors = resolveTypeParameters(functionDescriptor, innerScope, function.getTypeParameters());
+        innerScope.changeLockLevel(WritableScope.LockLevel.BOTH);
         resolveGenericBounds(function, innerScope, typeParameterDescriptors);
 
         JetType receiverType = null;
@@ -160,6 +161,8 @@ public class DescriptorResolver {
         
         List<ValueParameterDescriptor> valueParameterDescriptors = resolveValueParameters(functionDescriptor, innerScope, function.getValueParameters());
         
+        innerScope.changeLockLevel(WritableScope.LockLevel.READING);
+
         JetTypeReference returnTypeRef = function.getReturnTypeRef();
         JetType returnType;
         if (returnTypeRef != null) {
@@ -499,8 +502,10 @@ public class DescriptorResolver {
         }
         else {
             WritableScope writableScope = new WritableScopeImpl(scope, containingDeclaration, new TraceBasedRedeclarationHandler(trace)).setDebugName("Scope with type parameters of a property");
+            writableScope.changeLockLevel(WritableScope.LockLevel.BOTH);
             typeParameterDescriptors = resolveTypeParameters(containingDeclaration, writableScope, typeParameters);
             resolveGenericBounds(property, writableScope, typeParameterDescriptors);
+            writableScope.changeLockLevel(WritableScope.LockLevel.READING);
             scopeWithTypeParameters = writableScope;
         }
 
@@ -761,11 +766,13 @@ public class DescriptorResolver {
                 isPrimary
         );
         trace.record(BindingContext.CONSTRUCTOR, declarationToTrace, constructorDescriptor);
+        WritableScopeImpl parameterScope = new WritableScopeImpl(scope, classDescriptor, new TraceBasedRedeclarationHandler(trace)).setDebugName("Scope with value parameters of a constructor");
+        parameterScope.changeLockLevel(WritableScope.LockLevel.BOTH);
         return constructorDescriptor.initialize(
                 typeParameters,
                 resolveValueParameters(
                         constructorDescriptor,
-                        new WritableScopeImpl(scope, classDescriptor, new TraceBasedRedeclarationHandler(trace)).setDebugName("Scope with value parameters of a constructor"),
+                        parameterScope,
                         valueParameters),
                         Modality.FINAL,
                         resolveVisibilityFromModifiers(modifierList));

compiler/frontend/src/org/jetbrains/jet/lang/resolve/TopDownAnalyzer.java

@@ -60,6 +60,7 @@ public class TopDownAnalyzer {
         new TypeHierarchyResolver(context).process(outerScope, owner, declarations);
         new DeclarationResolver(context).process();
         new DelegationResolver(context).process();
+        lockClasses(context);
         new OverrideResolver(context).process();
         new OverloadResolver(context).process();
         if (!context.analyzingBootstrapLibrary()) {
@@ -72,6 +73,15 @@ public class TopDownAnalyzer {
         context.printDebugOutput(System.out);
     }
 
+    private static void lockClasses(TopDownAnalysisContext context) {
+        for (MutableClassDescriptor mutableClassDescriptor : context.getClasses().values()) {
+            mutableClassDescriptor.lockScopes();
+        }
+        for (MutableClassDescriptor mutableClassDescriptor : context.getObjects().values()) {
+            mutableClassDescriptor.lockScopes();
+        }
+    }
+
     public static void processStandardLibraryNamespace(
             @NotNull JetSemanticServices semanticServices,
             @NotNull BindingTrace trace,

compiler/frontend/src/org/jetbrains/jet/lang/resolve/TypeHierarchyResolver.java

@@ -78,13 +78,16 @@ public class TypeHierarchyResolver {
                                 Collections.<AnnotationDescriptor>emptyList(), // TODO: annotations
                                 name
                         );
-                        namespaceDescriptor.initialize(new WritableScopeImpl(JetScope.EMPTY, namespaceDescriptor, new TraceBasedRedeclarationHandler(context.getTrace())).setDebugName("Namespace member scope"));
+                        WritableScopeImpl memberScope = new WritableScopeImpl(JetScope.EMPTY, namespaceDescriptor, new TraceBasedRedeclarationHandler(context.getTrace())).setDebugName("Namespace member scope");
+                        memberScope.changeLockLevel(WritableScope.LockLevel.BOTH);
+                        namespaceDescriptor.initialize(memberScope);
                         owner.addNamespace(namespaceDescriptor);
                         context.getTrace().record(BindingContext.NAMESPACE, namespace, namespaceDescriptor);
                     }
                     context.getNamespaceDescriptors().put(namespace, namespaceDescriptor);
 
                     WriteThroughScope namespaceScope = new WriteThroughScope(outerScope, namespaceDescriptor.getMemberScope(), new TraceBasedRedeclarationHandler(context.getTrace()));
+                    namespaceScope.changeLockLevel(WritableScope.LockLevel.BOTH);
                     context.getNamespaceScopes().put(namespace, namespaceScope);
                     context.getDeclaringScopes().put(namespace, outerScope);
 

compiler/frontend/src/org/jetbrains/jet/lang/resolve/scopes/WritableScope.java

@@ -9,6 +9,14 @@ import org.jetbrains.jet.lang.resolve.scopes.receivers.ReceiverDescriptor;
  * @author abreslav
  */
 public interface WritableScope extends JetScope {
+    enum LockLevel {
+        WRITING,
+        BOTH,
+        READING,
+    }
+
+    void changeLockLevel(LockLevel lockLevel);
+
     void addLabeledDeclaration(@NotNull DeclarationDescriptor descriptor);
 
     void addVariableDescriptor(@NotNull VariableDescriptor variableDescriptor);

compiler/frontend/src/org/jetbrains/jet/lang/resolve/scopes/WritableScopeImpl.java

@@ -55,17 +55,22 @@ public class WritableScopeImpl extends WritableScopeWithImports {
 
     @Override
     public void importScope(@NotNull JetScope imported) {
+        checkMayWrite();
         super.importScope(imported);
     }
 
     @Override
     public void importClassifierAlias(@NotNull String importedClassifierName, @NotNull ClassifierDescriptor classifierDescriptor) {
+        checkMayWrite();
+
         allDescriptors.add(classifierDescriptor);
         super.importClassifierAlias(importedClassifierName, classifierDescriptor);
     }
 
     @Override
     public void importNamespaceAlias(String aliasName, NamespaceDescriptor namespaceDescriptor) {
+        checkMayWrite();
+
         allDescriptors.add(namespaceDescriptor);
         super.importNamespaceAlias(aliasName, namespaceDescriptor);
     }
@@ -73,6 +78,8 @@ public class WritableScopeImpl extends WritableScopeWithImports {
     @NotNull
     @Override
     public Collection<DeclarationDescriptor> getAllDescriptors() {
+        checkMayRead();
+
         if (!allDescriptorsDone) {
             allDescriptorsDone = true;
             allDescriptors.addAll(getWorkerScope().getAllDescriptors());
@@ -94,6 +101,8 @@ public class WritableScopeImpl extends WritableScopeWithImports {
     @NotNull
     @Override
     public Collection<DeclarationDescriptor> getDeclarationsByLabel(@NotNull String labelName) {
+        checkMayRead();
+
         Collection<DeclarationDescriptor> superResult = super.getDeclarationsByLabel(labelName);
         Map<String, List<DeclarationDescriptor>> labelsToDescriptors = getLabelsToDescriptors();
         List<DeclarationDescriptor> declarationDescriptors = labelsToDescriptors.get(labelName);
@@ -108,6 +117,8 @@ public class WritableScopeImpl extends WritableScopeWithImports {
 
     @Override
     public void addLabeledDeclaration(@NotNull DeclarationDescriptor descriptor) {
+        checkMayWrite();
+
         Map<String, List<DeclarationDescriptor>> labelsToDescriptors = getLabelsToDescriptors();
         String name = descriptor.getName();
         assert name != null;
@@ -137,6 +148,8 @@ public class WritableScopeImpl extends WritableScopeWithImports {
 
     @Override
     public void addVariableDescriptor(@NotNull VariableDescriptor variableDescriptor) {
+        checkMayWrite();
+
         Map<String, DeclarationDescriptor> variableClassOrNamespaceDescriptors = getVariableClassOrNamespaceDescriptors();
         DeclarationDescriptor existingDescriptor = variableClassOrNamespaceDescriptors.get(variableDescriptor.getName());
         if (existingDescriptor != null) {
@@ -149,6 +162,8 @@ public class WritableScopeImpl extends WritableScopeWithImports {
 
     @Override
     public VariableDescriptor getVariable(@NotNull String name) {
+        checkMayRead();
+
         Map<String, DeclarationDescriptor> variableClassOrNamespaceDescriptors = getVariableClassOrNamespaceDescriptors();
         DeclarationDescriptor descriptor = variableClassOrNamespaceDescriptors.get(name);
         if (descriptor instanceof VariableDescriptor) {
@@ -172,6 +187,8 @@ public class WritableScopeImpl extends WritableScopeWithImports {
 
     @Override
     public void addFunctionDescriptor(@NotNull FunctionDescriptor functionDescriptor) {
+        checkMayWrite();
+
         getFunctionGroups().put(functionDescriptor.getName(), functionDescriptor);
         allDescriptors.add(functionDescriptor);
     }
@@ -179,6 +196,8 @@ public class WritableScopeImpl extends WritableScopeWithImports {
     @Override
     @NotNull
     public Set<FunctionDescriptor> getFunctions(@NotNull String name) {
+        checkMayRead();
+
         Set<FunctionDescriptor> result = Sets.newLinkedHashSet(getFunctionGroups().get(name));
 
         result.addAll(getWorkerScope().getFunctions(name));
@@ -190,17 +209,23 @@ public class WritableScopeImpl extends WritableScopeWithImports {
 
     @Override
     public void addTypeParameterDescriptor(@NotNull TypeParameterDescriptor typeParameterDescriptor) {
+        checkMayWrite();
+
         String name = typeParameterDescriptor.getName();
         addClassifierAlias(name, typeParameterDescriptor);
     }
 
     @Override
     public void addClassifierDescriptor(@NotNull ClassifierDescriptor classDescriptor) {
+        checkMayWrite();
+
         addClassifierAlias(classDescriptor.getName(), classDescriptor);
     }
 
     @Override
     public void addClassifierAlias(@NotNull String name, @NotNull ClassifierDescriptor classifierDescriptor) {
+        checkMayWrite();
+
         checkForRedeclaration(name, classifierDescriptor);
         getVariableClassOrNamespaceDescriptors().put(name, classifierDescriptor);
         allDescriptors.add(classifierDescriptor);
@@ -208,6 +233,8 @@ public class WritableScopeImpl extends WritableScopeWithImports {
 
     @Override
     public void addNamespaceAlias(@NotNull String name, @NotNull NamespaceDescriptor namespaceDescriptor) {
+        checkMayWrite();
+
         checkForRedeclaration(name, namespaceDescriptor);
         getNamespaceAliases().put(name, namespaceDescriptor);
         allDescriptors.add(namespaceDescriptor);
@@ -222,6 +249,8 @@ public class WritableScopeImpl extends WritableScopeWithImports {
 
     @Override
     public ClassifierDescriptor getClassifier(@NotNull String name) {
+        checkMayRead();
+
         Map<String, DeclarationDescriptor> variableClassOrNamespaceDescriptors = getVariableClassOrNamespaceDescriptors();
         DeclarationDescriptor descriptor = variableClassOrNamespaceDescriptors.get(name);
         if (descriptor instanceof ClassifierDescriptor) return (ClassifierDescriptor) descriptor;
@@ -234,6 +263,8 @@ public class WritableScopeImpl extends WritableScopeWithImports {
 
     @Override
     public void addNamespace(@NotNull NamespaceDescriptor namespaceDescriptor) {
+        checkMayWrite();
+
         Map<String, DeclarationDescriptor> variableClassOrNamespaceDescriptors = getVariableClassOrNamespaceDescriptors();
         DeclarationDescriptor oldValue = variableClassOrNamespaceDescriptors.put(namespaceDescriptor.getName(), namespaceDescriptor);
         if (oldValue != null) {
@@ -244,6 +275,8 @@ public class WritableScopeImpl extends WritableScopeWithImports {
 
     @Override
     public NamespaceDescriptor getDeclaredNamespace(@NotNull String name) {
+        checkMayRead();
+
         Map<String, DeclarationDescriptor> variableClassOrNamespaceDescriptors = getVariableClassOrNamespaceDescriptors();
         DeclarationDescriptor namespaceDescriptor = variableClassOrNamespaceDescriptors.get(name);
         if (namespaceDescriptor instanceof NamespaceDescriptor) return (NamespaceDescriptor) namespaceDescriptor;
@@ -252,6 +285,8 @@ public class WritableScopeImpl extends WritableScopeWithImports {
 
     @Override
     public NamespaceDescriptor getNamespace(@NotNull String name) {
+        checkMayRead();
+
         NamespaceDescriptor declaredNamespace = getDeclaredNamespace(name);
         if (declaredNamespace != null) return declaredNamespace;
 
@@ -266,6 +301,8 @@ public class WritableScopeImpl extends WritableScopeWithImports {
     @NotNull
     @Override
     public ReceiverDescriptor getImplicitReceiver() {
+        checkMayRead();
+
         if (implicitReceiver == null) {
             return super.getImplicitReceiver();
         }
@@ -274,6 +311,8 @@ public class WritableScopeImpl extends WritableScopeWithImports {
 
     @Override
     public void setImplicitReceiver(@NotNull ReceiverDescriptor implicitReceiver) {
+        checkMayWrite();
+
         if (this.implicitReceiver != null) {
             throw new UnsupportedOperationException("Receiver redeclared");
         }
@@ -282,6 +321,8 @@ public class WritableScopeImpl extends WritableScopeWithImports {
 
     @Override
     public void getImplicitReceiversHierarchy(@NotNull List<ReceiverDescriptor> result) {
+        checkMayRead();
+
         if (implicitReceiver != null && implicitReceiver.exists()) {
             result.add(implicitReceiver);
         }
@@ -303,6 +344,8 @@ public class WritableScopeImpl extends WritableScopeWithImports {
             throw new IllegalStateException();
         }
         
+        checkMayWrite();
+
         getPropertyDescriptorsByFieldNames().put(fieldName, propertyDescriptor);
     }
 
@@ -312,12 +355,16 @@ public class WritableScopeImpl extends WritableScopeWithImports {
             throw new IllegalStateException();
         }
 
+        checkMayRead();
+
         PropertyDescriptor descriptor = getPropertyDescriptorsByFieldNames().get(fieldName);
         if (descriptor != null) return descriptor;
         return super.getPropertyByFieldReference(fieldName);
     }
 
     public List<VariableDescriptor> getDeclaredVariables() {
+        checkMayRead();
+
         List<VariableDescriptor> result = Lists.newArrayList();
         for (DeclarationDescriptor descriptor : getVariableClassOrNamespaceDescriptors().values()) {
             if (descriptor instanceof VariableDescriptor) {
@@ -334,6 +381,8 @@ public class WritableScopeImpl extends WritableScopeWithImports {
 
     @Override
     public WritableScopeImpl setDebugName(@NotNull String debugName) {
+        checkMayWrite();
+
         super.setDebugName(debugName);
         return this;
     }

compiler/frontend/src/org/jetbrains/jet/lang/resolve/scopes/WritableScopeWithImports.java

@@ -31,7 +31,36 @@ public abstract class WritableScopeWithImports extends JetScopeAdapter implement
         this.redeclarationHandler = redeclarationHandler;
     }
 
+
+
+    private LockLevel lockLevel = LockLevel.WRITING;
+
+    @Override
+    public void changeLockLevel(LockLevel lockLevel) {
+        if (lockLevel.ordinal() < this.lockLevel.ordinal()) {
+            throw new IllegalStateException("cannot lower lock level from " + this.lockLevel + " to " + lockLevel);
+        }
+        this.lockLevel = lockLevel;
+    }
+
+    protected void checkMayRead() {
+        if (lockLevel != LockLevel.READING && lockLevel != LockLevel.BOTH) {
+            throw new IllegalStateException("cannot read with lock level " + lockLevel);
+        }
+    }
+
+    protected void checkMayWrite() {
+        if (lockLevel != LockLevel.WRITING && lockLevel != LockLevel.BOTH) {
+            throw new IllegalStateException("cannot write with lock level " + lockLevel);
+        }
+    }
+
+
+
+
     public WritableScopeWithImports setDebugName(@NotNull String debugName) {
+        checkMayWrite();
+
         assert this.debugName == null : this.debugName;
         this.debugName = debugName;
         return this;
@@ -47,12 +76,16 @@ public abstract class WritableScopeWithImports extends JetScopeAdapter implement
 
     @Override
     public void importScope(@NotNull JetScope imported) {
+        checkMayWrite();
+
         getImports().add(0, imported);
         currentIndividualImportScope = null;
     }
 
     @Override
     public void getImplicitReceiversHierarchy(@NotNull List<ReceiverDescriptor> result) {
+        checkMayRead();
+
         super.getImplicitReceiversHierarchy(result);
         // Imported scopes come with their receivers
         // Example: class member resolution scope imports a scope of it's class object
@@ -67,6 +100,8 @@ public abstract class WritableScopeWithImports extends JetScopeAdapter implement
 
     @Override
     public VariableDescriptor getVariable(@NotNull String name) {
+        checkMayRead();
+
         // Meaningful lookup goes here
         for (JetScope imported : getImports()) {
             VariableDescriptor importedDescriptor = imported.getVariable(name);
@@ -80,6 +115,8 @@ public abstract class WritableScopeWithImports extends JetScopeAdapter implement
     @NotNull
     @Override
     public Set<FunctionDescriptor> getFunctions(@NotNull String name) {
+        checkMayRead();
+
         if (getImports().isEmpty()) {
             return Collections.emptySet();
         }
@@ -92,6 +129,8 @@ public abstract class WritableScopeWithImports extends JetScopeAdapter implement
 
     @Override
     public ClassifierDescriptor getClassifier(@NotNull String name) {
+        checkMayRead();
+
         for (JetScope imported : getImports()) {
             ClassifierDescriptor importedClassifier = imported.getClassifier(name);
             if (importedClassifier != null) {
@@ -103,6 +142,8 @@ public abstract class WritableScopeWithImports extends JetScopeAdapter implement
 
     @Override
     public NamespaceDescriptor getNamespace(@NotNull String name) {
+        checkMayRead();
+
         for (JetScope imported : getImports()) {
             NamespaceDescriptor importedDescriptor = imported.getNamespace(name);
             if (importedDescriptor != null) {
@@ -115,6 +156,7 @@ public abstract class WritableScopeWithImports extends JetScopeAdapter implement
     private WritableScope getCurrentIndividualImportScope() {
         if (currentIndividualImportScope == null) {
             WritableScopeImpl writableScope = new WritableScopeImpl(EMPTY, getContainingDeclaration(), RedeclarationHandler.DO_NOTHING).setDebugName("Individual import scope");
+            writableScope.changeLockLevel(LockLevel.BOTH);
             importScope(writableScope);
             currentIndividualImportScope = writableScope;
         }
@@ -123,12 +165,16 @@ public abstract class WritableScopeWithImports extends JetScopeAdapter implement
 
     @Override
     public void importClassifierAlias(@NotNull String importedClassifierName, @NotNull ClassifierDescriptor classifierDescriptor) {
+        checkMayWrite();
+
         getCurrentIndividualImportScope().addClassifierAlias(importedClassifierName, classifierDescriptor);
     }
     
     
     @Override
     public void importNamespaceAlias(String aliasName, NamespaceDescriptor namespaceDescriptor) {
+        checkMayWrite();
+
         getCurrentIndividualImportScope().addNamespaceAlias(aliasName, namespaceDescriptor);
     }
     

compiler/frontend/src/org/jetbrains/jet/lang/resolve/scopes/WriteThroughScope.java

@@ -25,30 +25,40 @@ public class WriteThroughScope extends WritableScopeWithImports {
     @Override
     @Nullable
     public PropertyDescriptor getPropertyByFieldReference(@NotNull String fieldName) {
+        checkMayRead();
+
         return writableWorker.getPropertyByFieldReference(fieldName);
     }
 
     @Override
     @NotNull
     public Collection<DeclarationDescriptor> getDeclarationsByLabel(String labelName) {
+        checkMayRead();
+
         return writableWorker.getDeclarationsByLabel(labelName);
     }
 
     @Override
     @NotNull
     public DeclarationDescriptor getContainingDeclaration() {
+        checkMayRead();
+
         return writableWorker.getContainingDeclaration();
     }
 
     @Override
     @NotNull
     public ReceiverDescriptor getImplicitReceiver() {
+        checkMayRead();
+
         return writableWorker.getImplicitReceiver();
     }
 
     @Override
     @NotNull
     public Set<FunctionDescriptor> getFunctions(@NotNull String name) {
+        checkMayRead();
+
         Set<FunctionDescriptor> result = Sets.newLinkedHashSet();
 
         result.addAll(writableWorker.getFunctions(name));
@@ -63,6 +73,8 @@ public class WriteThroughScope extends WritableScopeWithImports {
     @Override
     @Nullable
     public VariableDescriptor getVariable(@NotNull String name) {
+        checkMayRead();
+
         VariableDescriptor variable = writableWorker.getVariable(name);
         if (variable != null) return variable;
 
@@ -75,6 +87,8 @@ public class WriteThroughScope extends WritableScopeWithImports {
     @Override
     @Nullable
     public NamespaceDescriptor getNamespace(@NotNull String name) {
+        checkMayRead();
+
         NamespaceDescriptor namespace = writableWorker.getNamespace(name);
         if (namespace != null) return namespace;
 
@@ -87,6 +101,8 @@ public class WriteThroughScope extends WritableScopeWithImports {
     @Override
     @Nullable
     public ClassifierDescriptor getClassifier(@NotNull String name) {
+        checkMayRead();
+
         ClassifierDescriptor classifier = writableWorker.getClassifier(name);
         if (classifier != null) return classifier;
 
@@ -98,68 +114,94 @@ public class WriteThroughScope extends WritableScopeWithImports {
 
     @Override
     public void addLabeledDeclaration(@NotNull DeclarationDescriptor descriptor) {
+        checkMayWrite();
+
         writableWorker.addLabeledDeclaration(descriptor); // TODO : review
     }
 
     @Override
     public void addVariableDescriptor(@NotNull VariableDescriptor variableDescriptor) {
+        checkMayWrite();
+
         writableWorker.addVariableDescriptor(variableDescriptor);
     }
 
     @Override
     public void addFunctionDescriptor(@NotNull FunctionDescriptor functionDescriptor) {
+        checkMayWrite();
+
         writableWorker.addFunctionDescriptor(functionDescriptor);
     }
 
     @Override
     public void addTypeParameterDescriptor(@NotNull TypeParameterDescriptor typeParameterDescriptor) {
+        checkMayWrite();
+
         writableWorker.addTypeParameterDescriptor(typeParameterDescriptor);
     }
 
     @Override
     public void addClassifierDescriptor(@NotNull ClassifierDescriptor classDescriptor) {
+        checkMayWrite();
+
         writableWorker.addClassifierDescriptor(classDescriptor);
     }
 
     @Override
     public void addClassifierAlias(@NotNull String name, @NotNull ClassifierDescriptor classifierDescriptor) {
+        checkMayWrite();
+
         writableWorker.addClassifierAlias(name, classifierDescriptor);
     }
 
     @Override
     public void addNamespaceAlias(@NotNull String name, @NotNull NamespaceDescriptor namespaceDescriptor) {
+        checkMayWrite();
+
         writableWorker.addNamespaceAlias(name, namespaceDescriptor);
     }
 
     @Override
     public void addNamespace(@NotNull NamespaceDescriptor namespaceDescriptor) {
+        checkMayWrite();
+
         writableWorker.addNamespace(namespaceDescriptor);
     }
 
     @Override
     @Nullable
     public NamespaceDescriptor getDeclaredNamespace(@NotNull String name) {
+        checkMayRead();
+
         return writableWorker.getDeclaredNamespace(name);
     }
 
     @Override
     public void addPropertyDescriptorByFieldName(@NotNull String fieldName, @NotNull PropertyDescriptor propertyDescriptor) {
+        checkMayWrite();
+
         writableWorker.addPropertyDescriptorByFieldName(fieldName, propertyDescriptor);
     }
 
     @Override
     public void importScope(@NotNull JetScope imported) {
+        checkMayWrite();
+
         super.importScope(imported); //
     }
 
     @Override
     public void setImplicitReceiver(@NotNull ReceiverDescriptor implicitReceiver) {
+        checkMayWrite();
+
         writableWorker.setImplicitReceiver(implicitReceiver);
     }
 
     @NotNull
     @Override
     public Collection<DeclarationDescriptor> getAllDescriptors() {
+        checkMayRead();
+
         if (allDescriptors == null) {
             allDescriptors = Lists.newArrayList();
             allDescriptors.addAll(writableWorker.getAllDescriptors());
@@ -170,6 +212,8 @@ public class WriteThroughScope extends WritableScopeWithImports {
 
     @NotNull
     public JetScope getOuterScope() {
+        checkMayRead();
+
         return getWorkerScope();
     }
 }

compiler/frontend/src/org/jetbrains/jet/lang/types/JetStandardClasses.java

@@ -194,6 +194,8 @@ public class JetStandardClasses {
 
     static {
         WritableScope writableScope = new WritableScopeImpl(JetScope.EMPTY, STANDARD_CLASSES_NAMESPACE, RedeclarationHandler.DO_NOTHING).setDebugName("JetStandardClasses.STANDARD_CLASSES");
+        writableScope.changeLockLevel(WritableScope.LockLevel.BOTH);
+
         STANDARD_CLASSES = writableScope;
         writableScope.addClassifierAlias("Unit", getTuple(0));
 

compiler/frontend/src/org/jetbrains/jet/lang/types/JetStandardLibrary.java

@@ -13,6 +13,7 @@ import org.jetbrains.jet.lang.psi.JetFile;
 import org.jetbrains.jet.lang.resolve.*;
 import org.jetbrains.jet.lang.resolve.scopes.JetScope;
 import org.jetbrains.jet.lang.resolve.scopes.RedeclarationHandler;
+import org.jetbrains.jet.lang.resolve.scopes.WritableScope;
 import org.jetbrains.jet.lang.resolve.scopes.WritableScopeImpl;
 import org.jetbrains.jet.plugin.JetFileType;
 
@@ -133,6 +134,7 @@ public class JetStandardLibrary {
             JetSemanticServices bootstrappingSemanticServices = JetSemanticServices.createSemanticServices(this);
             BindingTraceContext bindingTraceContext = new BindingTraceContext();
             WritableScopeImpl writableScope = new WritableScopeImpl(JetStandardClasses.STANDARD_CLASSES, JetStandardClasses.STANDARD_CLASSES_NAMESPACE, RedeclarationHandler.THROW_EXCEPTION).setDebugName("Root bootstrap scope");
+            writableScope.changeLockLevel(WritableScope.LockLevel.BOTH);
 //            this.libraryScope = bootstrappingTDA.process(JetStandardClasses.STANDARD_CLASSES, file.getRootNamespace().getDeclarations());
 //            bootstrappingTDA.process(writableScope, JetStandardClasses.STANDARD_CLASSES_NAMESPACE, file.getRootNamespace().getDeclarations());
             TopDownAnalyzer.processStandardLibraryNamespace(bootstrappingSemanticServices, bindingTraceContext, writableScope, JetStandardClasses.STANDARD_CLASSES_NAMESPACE, file.getRootNamespace());

compiler/frontend/src/org/jetbrains/jet/lang/types/expressions/ExpressionTypingServices.java

@@ -140,6 +140,7 @@ public class ExpressionTypingServices {
 
         DeclarationDescriptor containingDescriptor = outerScope.getContainingDeclaration();
         WritableScope scope = new WritableScopeImpl(outerScope, containingDescriptor, new TraceBasedRedeclarationHandler(context.trace)).setDebugName("getBlockReturnedType");
+        scope.changeLockLevel(WritableScope.LockLevel.BOTH);
         return getBlockReturnedTypeWithWritableScope(scope, block, coercionStrategyForLastExpression, context);
     }
 

compiler/frontend/src/org/jetbrains/jet/lang/types/expressions/ExpressionTypingUtils.java

@@ -13,6 +13,7 @@ import org.jetbrains.jet.lang.psi.JetExpression;
 import org.jetbrains.jet.lang.psi.JetSimpleNameExpression;
 import org.jetbrains.jet.lang.resolve.BindingContextUtils;
 import org.jetbrains.jet.lang.resolve.TraceBasedRedeclarationHandler;
+import org.jetbrains.jet.lang.resolve.scopes.WritableScope;
 import org.jetbrains.jet.lang.resolve.scopes.WritableScopeImpl;
 import org.jetbrains.jet.lang.resolve.scopes.receivers.ExpressionReceiver;
 import org.jetbrains.jet.lang.types.JetStandardClasses;
@@ -42,7 +43,9 @@ public class ExpressionTypingUtils {
 
     @NotNull
     public static WritableScopeImpl newWritableScopeImpl(ExpressionTypingContext context) {
-        return new WritableScopeImpl(context.scope, context.scope.getContainingDeclaration(), new TraceBasedRedeclarationHandler(context.trace));
+        WritableScopeImpl scope = new WritableScopeImpl(context.scope, context.scope.getContainingDeclaration(), new TraceBasedRedeclarationHandler(context.trace));
+        scope.changeLockLevel(WritableScope.LockLevel.BOTH);
+        return scope;
     }
 
     public static boolean isBoolean(@NotNull JetSemanticServices semanticServices, @NotNull JetType type) {

compiler/tests/org/jetbrains/jet/types/JetDefaultModalityModifiersTest.java

@@ -10,6 +10,7 @@ import org.jetbrains.jet.lang.resolve.DescriptorResolver;
 import org.jetbrains.jet.lang.resolve.java.AnalyzerFacade;
 import org.jetbrains.jet.lang.resolve.scopes.JetScope;
 import org.jetbrains.jet.lang.resolve.scopes.RedeclarationHandler;
+import org.jetbrains.jet.lang.resolve.scopes.WritableScope;
 import org.jetbrains.jet.lang.resolve.scopes.WritableScopeImpl;
 import org.jetbrains.jet.lang.types.JetStandardLibrary;
 
@@ -49,6 +50,7 @@ public class JetDefaultModalityModifiersTest extends JetLiteFixture {
             WritableScopeImpl scope = new WritableScopeImpl(libraryScope, root, RedeclarationHandler.DO_NOTHING);
             assert classDescriptor instanceof ClassifierDescriptor;
             scope.addClassifierDescriptor((ClassifierDescriptor) classDescriptor);
+            scope.changeLockLevel(WritableScope.LockLevel.READING);
             return scope;
         }
 

compiler/tests/org/jetbrains/jet/types/JetTypeCheckerTest.java

@@ -545,6 +545,7 @@ public class JetTypeCheckerTest extends JetLiteFixture {
         JavaSemanticServices javaSemanticServices = new JavaSemanticServices(getProject(), semanticServices, JetTestUtils.DUMMY_TRACE);
         writableScope.importScope(new JavaPackageScope("", null, javaSemanticServices));
         writableScope.importScope(new JavaPackageScope("java.lang", null, javaSemanticServices));
+        writableScope.changeLockLevel(WritableScope.LockLevel.BOTH);
         return writableScope;
     }
 
@@ -641,6 +642,7 @@ public class JetTypeCheckerTest extends JetLiteFixture {
             trace.record(BindingContext.CLASS, classElement, classDescriptor);
 
             final WritableScope parameterScope = new WritableScopeImpl(scope, classDescriptor, new TraceBasedRedeclarationHandler(trace));
+            parameterScope.changeLockLevel(WritableScope.LockLevel.BOTH);
 
             // This call has side-effects on the parameterScope (fills it in)
             List<TypeParameterDescriptor> typeParameters
@@ -660,6 +662,7 @@ public class JetTypeCheckerTest extends JetLiteFixture {
             boolean open = classElement.hasModifier(JetTokens.OPEN_KEYWORD);
 
             final WritableScope memberDeclarations = new WritableScopeImpl(JetScope.EMPTY, classDescriptor, new TraceBasedRedeclarationHandler(trace));
+            memberDeclarations.changeLockLevel(WritableScope.LockLevel.BOTH);
 
             List<JetDeclaration> declarations = classElement.getDeclarations();
             for (JetDeclaration declaration : declarations) {