Merge stored empty lists and sets to singe object

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

@@ -39,6 +39,7 @@ import org.jetbrains.jet.storage.MemoizedFunctionToNotNull;
 import org.jetbrains.jet.storage.NotNullLazyValue;
 import org.jetbrains.jet.storage.StorageManager;
 import org.jetbrains.jet.utils.Printer;
+import org.jetbrains.jet.utils.UtilsPackage;
 
 import java.util.*;
 
@@ -106,7 +107,7 @@ public abstract class AbstractLazyMemberScope<D extends DeclarationDescriptor, D
     private List<ClassDescriptor> resolveClassDescriptor(@NotNull final Name name) {
         Collection<JetClassLikeInfo> classOrObjectDeclarations = declarationProvider.getClassOrObjectDeclarations(name);
 
-        return ContainerUtil.mapNotNull(classOrObjectDeclarations, new Function<JetClassLikeInfo, ClassDescriptor>() {
+        return UtilsPackage.toReadOnlyList(ContainerUtil.mapNotNull(classOrObjectDeclarations, new Function<JetClassLikeInfo, ClassDescriptor>() {
             @Override
             public ClassDescriptor fun(JetClassLikeInfo classLikeInfo) {
                 // SCRIPT: Creating a script class
@@ -115,7 +116,7 @@ public abstract class AbstractLazyMemberScope<D extends DeclarationDescriptor, D
                 }
                 return new LazyClassDescriptor(resolveSession, thisDescriptor, name, classLikeInfo);
             }
-        });
+        }));
     }
 
     @Override
@@ -153,7 +154,7 @@ public abstract class AbstractLazyMemberScope<D extends DeclarationDescriptor, D
 
         getNonDeclaredFunctions(name, result);
 
-        return result;
+        return UtilsPackage.toReadOnlySet(result);
     }
 
     @NotNull
@@ -189,7 +190,7 @@ public abstract class AbstractLazyMemberScope<D extends DeclarationDescriptor, D
 
         getNonDeclaredProperties(name, result);
 
-        return result;
+        return UtilsPackage.toReadOnlySet(result);
     }
 
     protected abstract void getNonDeclaredProperties(@NotNull Name name, @NotNull Set<VariableDescriptor> result);
@@ -252,8 +253,8 @@ public abstract class AbstractLazyMemberScope<D extends DeclarationDescriptor, D
                 throw new IllegalArgumentException("Unsupported declaration kind: " + declaration);
             }
         }
-        result.trimToSize();
-        return result;
+
+        return UtilsPackage.toReadOnlyList(result);
     }
 
     @NotNull

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

@@ -36,6 +36,7 @@ import org.jetbrains.jet.lang.types.DeferredType;
 import org.jetbrains.jet.lang.types.JetType;
 import org.jetbrains.jet.lang.types.lang.KotlinBuiltIns;
 import org.jetbrains.jet.storage.NullableLazyValue;
+import org.jetbrains.jet.utils.UtilsPackage;
 
 import java.util.*;
 
@@ -299,7 +300,7 @@ public class LazyClassMemberScope extends AbstractLazyMemberScope<LazyClassDescr
     @Override
     @NotNull
     protected Collection<DeclarationDescriptor> computeExtraDescriptors() {
-        ArrayList<DeclarationDescriptor> result = new ArrayList<DeclarationDescriptor>();
+        List<DeclarationDescriptor> result = new ArrayList<DeclarationDescriptor>();
         for (JetType supertype : thisDescriptor.getTypeConstructor().getSupertypes()) {
             for (DeclarationDescriptor descriptor : supertype.getMemberScope().getAllDescriptors()) {
                 if (descriptor instanceof FunctionDescriptor) {
@@ -314,8 +315,7 @@ public class LazyClassMemberScope extends AbstractLazyMemberScope<LazyClassDescr
 
         addDataClassMethods(result);
 
-        result.trimToSize();
-        return result;
+        return UtilsPackage.toReadOnlyList(result);
     }
 
     private void addDataClassMethods(@NotNull Collection<DeclarationDescriptor> result) {

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

@@ -30,6 +30,7 @@ import org.jetbrains.jet.lang.resolve.lazy.data.JetScriptInfo;
 import org.jetbrains.jet.lang.resolve.lazy.declarations.ClassMemberDeclarationProvider;
 import org.jetbrains.jet.lang.resolve.name.Name;
 import org.jetbrains.jet.storage.NotNullLazyValue;
+import org.jetbrains.jet.utils.UtilsPackage;
 
 import java.util.Collection;
 import java.util.Set;
@@ -61,13 +62,13 @@ public class LazyScriptClassMemberScope extends LazyClassMemberScope {
     @NotNull
     @Override
     protected Collection<DeclarationDescriptor> computeExtraDescriptors() {
-        return KotlinPackage.plus(
+        return UtilsPackage.toReadOnlyList(KotlinPackage.plus(
                 super.computeExtraDescriptors(),
                 KotlinPackage.plus(
                     getProperties(Name.identifier(ScriptDescriptor.LAST_EXPRESSION_VALUE_FIELD_NAME)),
                     getPropertiesForScriptParameters()
                 )
-        );
+        ));
     }
 
     private Collection<VariableDescriptor> getPropertiesForScriptParameters() {