getImplicitReceiverHierarchy() returns a List

compiler/backend/src/org/jetbrains/jet/cli/jvm/compiler/TipsManager.java

@@ -105,7 +105,7 @@ public final class TipsManager {
             else {
                 Collection<DeclarationDescriptor> descriptorsSet = Sets.newHashSet();
 
-                List<ReceiverParameterDescriptor> result = JetScopeUtils.getImplicitReceiversHierarchy(resolutionScope);
+                List<ReceiverParameterDescriptor> result = resolutionScope.getImplicitReceiversHierarchy();
 
                 for (ReceiverParameterDescriptor receiverDescriptor : result) {
                     JetType receiverType = receiverDescriptor.getType();
@@ -153,7 +153,7 @@ public final class TipsManager {
     ) {
         final Set<DeclarationDescriptor> descriptorsSet = Sets.newHashSet(descriptors);
 
-        final List<ReceiverParameterDescriptor> result = JetScopeUtils.getImplicitReceiversHierarchy(scope);
+        final List<ReceiverParameterDescriptor> result = scope.getImplicitReceiversHierarchy();
 
         descriptorsSet.removeAll(
                 Collections2.filter(JetScopeUtils.getAllExtensions(scope), new Predicate<CallableDescriptor>() {

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

@@ -29,6 +29,7 @@ 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 java.util.Collections;
 import java.util.List;
 import java.util.Set;
 
@@ -243,10 +244,10 @@ public class MutableClassDescriptor extends MutableClassDescriptorLite implement
                             return classObjectDescriptor.getDefaultType().getMemberScope();
                         }
 
+                        @NotNull
                         @Override
-                        public void getImplicitReceiversHierarchy(@NotNull List<ReceiverParameterDescriptor> result) {
-                            super.getImplicitReceiversHierarchy(result);
-                            result.add(0, classObjectDescriptor.getThisAsReceiverParameter());
+                        public List<ReceiverParameterDescriptor> getImplicitReceiversHierarchy() {
+                            return Collections.singletonList(classObjectDescriptor.getThisAsReceiverParameter());
                         }
                     });
 

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

@@ -34,9 +34,10 @@ public abstract class AbstractScopeAdapter implements JetScope {
     @NotNull
     protected abstract JetScope getWorkerScope();
 
+    @NotNull
     @Override
-    public void getImplicitReceiversHierarchy(@NotNull List<ReceiverParameterDescriptor> result) {
-        getWorkerScope().getImplicitReceiversHierarchy(result);
+    public List<ReceiverParameterDescriptor> getImplicitReceiversHierarchy() {
+        return getWorkerScope().getImplicitReceiversHierarchy();
     }
 
     @NotNull

compiler/frontend/src/org/jetbrains/jet/lang/resolve/calls/tasks/TaskPrioritizer.java

@@ -226,7 +226,7 @@ public abstract class TaskPrioritizer {
     private static <D extends CallableDescriptor> boolean setImpliedThis(@NotNull JetScope scope, ResolutionCandidate<D> candidate) {
         ReceiverParameterDescriptor expectedThisObject = candidate.getDescriptor().getExpectedThisObject();
         if (!expectedThisObject.exists()) return true;
-        List<ReceiverParameterDescriptor> receivers = JetScopeUtils.getImplicitReceiversHierarchy(scope);
+        List<ReceiverParameterDescriptor> receivers = scope.getImplicitReceiversHierarchy();
         for (ReceiverParameterDescriptor receiver : receivers) {
             if (JetTypeChecker.INSTANCE.isSubtypeOf(receiver.getType(), expectedThisObject.getType())) {
                 // TODO : Autocasts & nullability

compiler/frontend/src/org/jetbrains/jet/lang/resolve/lazy/AbstractLazyMemberScope.java

@@ -260,12 +260,14 @@ public abstract class AbstractLazyMemberScope<D extends DeclarationDescriptor, D
 
     protected abstract void addExtraDescriptors();
 
+    @NotNull
     @Override
-    public void getImplicitReceiversHierarchy(@NotNull List<ReceiverParameterDescriptor> result) {
+    public List<ReceiverParameterDescriptor> getImplicitReceiversHierarchy() {
         ReceiverParameterDescriptor receiver = getImplicitReceiver();
         if (receiver.exists()) {
-            result.add(receiver);
+            return Collections.singletonList(receiver);
         }
+        return Collections.emptyList();
     }
 
     @NotNull

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

@@ -16,6 +16,7 @@
 
 package org.jetbrains.jet.lang.resolve.scopes;
 
+import com.google.common.collect.Lists;
 import com.google.common.collect.Sets;
 import org.jetbrains.annotations.NotNull;
 import org.jetbrains.jet.lang.descriptors.*;
@@ -34,6 +35,7 @@ public class ChainedScope implements JetScope {
     private final DeclarationDescriptor containingDeclaration;
     private final JetScope[] scopeChain;
     private Collection<DeclarationDescriptor> allDescriptors;
+    private List<ReceiverParameterDescriptor> implicitReceiverHierarchy;
 
     public ChainedScope(DeclarationDescriptor containingDeclaration, JetScope... scopes) {
         this.containingDeclaration = containingDeclaration;
@@ -114,11 +116,16 @@ public class ChainedScope implements JetScope {
         return result;
     }
 
+    @NotNull
     @Override
-    public void getImplicitReceiversHierarchy(@NotNull List<ReceiverParameterDescriptor> result) {
-        for (JetScope jetScope : scopeChain) {
-            jetScope.getImplicitReceiversHierarchy(result);
+    public List<ReceiverParameterDescriptor> getImplicitReceiversHierarchy() {
+        if (implicitReceiverHierarchy == null) {
+            implicitReceiverHierarchy = Lists.newArrayList();
+            for (JetScope jetScope : scopeChain) {
+                implicitReceiverHierarchy.addAll(jetScope.getImplicitReceiversHierarchy());
+            }
         }
+        return implicitReceiverHierarchy;
     }
 
     @NotNull

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

@@ -29,6 +29,7 @@ import org.jetbrains.jet.lang.resolve.name.LabelName;
 import org.jetbrains.jet.lang.resolve.name.Name;
 
 import java.util.Collection;
+import java.util.Collections;
 import java.util.List;
 
 /**
@@ -82,9 +83,10 @@ public class InnerClassesScopeWrapper extends AbstractScopeAdapter {
         });
     }
 
+    @NotNull
     @Override
-    public void getImplicitReceiversHierarchy(@NotNull List<ReceiverParameterDescriptor> result) {
-        // Do nothing
+    public List<ReceiverParameterDescriptor> getImplicitReceiversHierarchy() {
+        return Collections.emptyList();
     }
 
     @Override

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

@@ -86,9 +86,9 @@ public interface JetScope {
 
     /**
      * Adds receivers to the list in order of locality, so that the closest (the most local) receiver goes first
-     * @param result
      */
-    void getImplicitReceiversHierarchy(@NotNull List<ReceiverParameterDescriptor> result);
+    @NotNull
+    List<ReceiverParameterDescriptor> getImplicitReceiversHierarchy();
 
     @NotNull
     Collection<DeclarationDescriptor> getOwnDeclaredDescriptors();

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

@@ -85,8 +85,10 @@ public abstract class JetScopeImpl implements JetScope {
         return Collections.emptyList();
     }
 
+    @NotNull
     @Override
-    public void getImplicitReceiversHierarchy(@NotNull List<ReceiverParameterDescriptor> result) {
+    public List<ReceiverParameterDescriptor> getImplicitReceiversHierarchy() {
+        return Collections.emptyList();
     }
 
     @NotNull

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

@@ -36,22 +36,8 @@ import java.util.Set;
 public final class JetScopeUtils {
     private JetScopeUtils() {}
 
-    /**
-     * Get receivers in order of locality, so that the closest (the most local) receiver goes first
-     * A wrapper for {@link JetScope#getImplicitReceiversHierarchy(List)}
-     *
-     * @param scope Scope for getting receivers hierarchy.
-     * @return receivers hierarchy.
-     */
-    @NotNull
-    public static List<ReceiverParameterDescriptor> getImplicitReceiversHierarchy(@NotNull JetScope scope) {
-        List<ReceiverParameterDescriptor> descriptors = Lists.newArrayList();
-        scope.getImplicitReceiversHierarchy(descriptors);
-        return descriptors;
-    }
-
     public static List<ReceiverDescriptor> getImplicitReceiversHierarchyValues(@NotNull JetScope scope) {
-        Collection<ReceiverParameterDescriptor> hierarchy = getImplicitReceiversHierarchy(scope);
+        Collection<ReceiverParameterDescriptor> hierarchy = scope.getImplicitReceiversHierarchy();
 
         return Lists.newArrayList(
                 Collections2.transform(hierarchy,

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

@@ -118,8 +118,9 @@ public class SubstitutingScope implements JetScope {
         return workerScope.getNamespace(name); // TODO
     }
 
+    @NotNull
     @Override
-    public void getImplicitReceiversHierarchy(@NotNull List<ReceiverParameterDescriptor> result) {
+    public List<ReceiverParameterDescriptor> getImplicitReceiversHierarchy() {
         throw new UnsupportedOperationException(); // TODO
     }
 

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

@@ -462,14 +462,13 @@ public class WritableScopeImpl extends WritableScopeWithImports {
     }
 
     @Override
-    public void getImplicitReceiversHierarchy(@NotNull List<ReceiverParameterDescriptor> result) {
-        checkMayRead();
-
-        super.getImplicitReceiversHierarchy(result);
-
+    protected List<ReceiverParameterDescriptor> computeImplicitReceiversHierarchy() {
+        List<ReceiverParameterDescriptor> implicitReceiverHierarchy = Lists.newArrayList();
         if (implicitReceiver != null && implicitReceiver.exists()) {
-            result.add(0, implicitReceiver);
+            implicitReceiverHierarchy.add(implicitReceiver);
         }
+        implicitReceiverHierarchy.addAll(super.computeImplicitReceiversHierarchy());
+        return implicitReceiverHierarchy;
     }
 
 //    @SuppressWarnings({"NullableProblems"})

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

@@ -16,17 +16,14 @@
 
 package org.jetbrains.jet.lang.resolve.scopes;
 
+import com.google.common.collect.Lists;
 import com.google.common.collect.Sets;
 import org.jetbrains.annotations.NotNull;
 import org.jetbrains.annotations.Nullable;
 import org.jetbrains.jet.lang.descriptors.*;
 import org.jetbrains.jet.lang.resolve.name.Name;
 
-import java.util.ArrayList;
-import java.util.Collection;
-import java.util.Collections;
-import java.util.List;
-import java.util.Set;
+import java.util.*;
 
 /**
  * @author abreslav
@@ -40,6 +37,7 @@ public abstract class WritableScopeWithImports extends JetScopeAdapter implement
     private List<JetScope> imports;
     private WritableScope currentIndividualImportScope;
     protected final RedeclarationHandler redeclarationHandler;
+    private List<ReceiverParameterDescriptor> implicitReceiverHierarchy;
 
     public WritableScopeWithImports(@NotNull JetScope scope, @NotNull RedeclarationHandler redeclarationHandler, @NotNull String debugName) {
         super(scope);
@@ -101,17 +99,27 @@ public abstract class WritableScopeWithImports extends JetScopeAdapter implement
         currentIndividualImportScope = null;
     }
 
+    @NotNull
     @Override
-    public void getImplicitReceiversHierarchy(@NotNull List<ReceiverParameterDescriptor> result) {
+    public List<ReceiverParameterDescriptor> getImplicitReceiversHierarchy() {
         checkMayRead();
 
-        super.getImplicitReceiversHierarchy(result);
+        if (implicitReceiverHierarchy == null) {
+            implicitReceiverHierarchy = computeImplicitReceiversHierarchy();
+        }
+        return implicitReceiverHierarchy;
+    }
+
+    protected List<ReceiverParameterDescriptor> computeImplicitReceiversHierarchy() {
+        List<ReceiverParameterDescriptor> implicitReceiverHierarchy = Lists.newArrayList();
         // Imported scopes come with their receivers
         // Example: class member resolution scope imports a scope of it's class object
         //          members of the class object must be able to find it as an implicit receiver
         for (JetScope scope : getImports()) {
-            scope.getImplicitReceiversHierarchy(result);
+            implicitReceiverHierarchy.addAll(scope.getImplicitReceiversHierarchy());
         }
+        implicitReceiverHierarchy.addAll(super.getImplicitReceiversHierarchy());
+        return implicitReceiverHierarchy;
     }
 
     @NotNull

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

@@ -76,8 +76,10 @@ public class ErrorUtils {
             return null; // TODO : review
         }
 
+        @NotNull
         @Override
-        public void getImplicitReceiversHierarchy(@NotNull List<ReceiverParameterDescriptor> result) {
+        public List<ReceiverParameterDescriptor> getImplicitReceiversHierarchy() {
+            return Collections.emptyList();
         }
 
         @NotNull

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

@@ -42,7 +42,6 @@ import org.jetbrains.jet.lang.resolve.constants.StringValue;
 import org.jetbrains.jet.lang.resolve.name.LabelName;
 import org.jetbrains.jet.lang.resolve.name.Name;
 import org.jetbrains.jet.lang.resolve.scopes.JetScope;
-import org.jetbrains.jet.lang.resolve.scopes.JetScopeUtils;
 import org.jetbrains.jet.lang.resolve.scopes.WritableScopeImpl;
 import org.jetbrains.jet.lang.resolve.scopes.receivers.ExpressionReceiver;
 import org.jetbrains.jet.lang.resolve.scopes.receivers.ReceiverDescriptor;
@@ -511,7 +510,7 @@ public class BasicExpressionTypingVisitor extends ExpressionTypingVisitor {
                     expression.getInstanceReference(), expression.getTargetLabel(), context, thisReceiver, new LabelName(labelName));
         }
         else {
-            List<ReceiverParameterDescriptor> receivers = JetScopeUtils.getImplicitReceiversHierarchy(context.scope);
+            List<ReceiverParameterDescriptor> receivers = context.scope.getImplicitReceiversHierarchy();
             if (onlyClassReceivers) {
                 for (ReceiverParameterDescriptor receiver : receivers) {
                     if (receiver.getContainingDeclaration() instanceof ClassDescriptor) {

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

@@ -16,6 +16,7 @@
 
 package org.jetbrains.jet.types;
 
+import com.google.common.collect.Lists;
 import com.google.common.collect.Sets;
 import com.intellij.openapi.project.Project;
 import org.jetbrains.annotations.NotNull;
@@ -32,7 +33,8 @@ import org.jetbrains.jet.lang.descriptors.annotations.AnnotationDescriptor;
 import org.jetbrains.jet.lang.psi.*;
 import org.jetbrains.jet.lang.resolve.*;
 import org.jetbrains.jet.lang.resolve.calls.autocasts.DataFlowInfo;
-import org.jetbrains.jet.lang.resolve.java.*;
+import org.jetbrains.jet.lang.resolve.java.DescriptorSearchRule;
+import org.jetbrains.jet.lang.resolve.java.JavaDescriptorResolver;
 import org.jetbrains.jet.lang.resolve.name.FqName;
 import org.jetbrains.jet.lang.resolve.name.Name;
 import org.jetbrains.jet.lang.resolve.scopes.*;
@@ -571,9 +573,10 @@ public class JetTypeCheckerTest extends JetLiteFixture {
     private void assertType(String contextType, final String expression, String expectedType) {
         final JetType thisType = makeType(contextType);
         JetScope scope = new JetScopeAdapter(classDefinitions.BASIC_SCOPE) {
+            @NotNull
             @Override
-            public void getImplicitReceiversHierarchy(@NotNull List<ReceiverParameterDescriptor> result) {
-                result.add(new ReceiverParameterDescriptorImpl(
+            public List<ReceiverParameterDescriptor> getImplicitReceiversHierarchy() {
+                return Lists.<ReceiverParameterDescriptor>newArrayList(new ReceiverParameterDescriptorImpl(
                         classDefinitions.BASIC_SCOPE.getContainingDeclaration(),
                         thisType,
                         new ExpressionReceiver(JetPsiFactory.createExpression(getProject(), expression), thisType)