@NotNull
  private JetType modifyTypeAccordingToSuperMethods(
      @NotNull JetType autoType,
      @NotNull List<TypeAndVariance> typesFromSuper,
      @NotNull TypeUsage howThisTypeIsUsed) {
    if (ErrorUtils.isErrorType(autoType)) {
      return autoType;
    }

    boolean resultNullable = typeMustBeNullable(autoType, typesFromSuper, howThisTypeIsUsed);
    ClassifierDescriptor resultClassifier = modifyTypeClassifier(autoType, typesFromSuper);
    List<TypeProjection> resultArguments =
        getTypeArgsOfType(autoType, resultClassifier, typesFromSuper);
    JetScope resultScope;
    if (resultClassifier instanceof ClassDescriptor) {
      resultScope = ((ClassDescriptor) resultClassifier).getMemberScope(resultArguments);
    } else {
      resultScope = autoType.getMemberScope();
    }

    JetTypeImpl type =
        new JetTypeImpl(
            autoType.getAnnotations(),
            resultClassifier.getTypeConstructor(),
            resultNullable,
            resultArguments,
            resultScope);

    PropagationHeuristics.checkArrayInReturnType(this, type, typesFromSuper);
    return type;
  }
  @NotNull
  private static Multimap<FqName, Pair<FunctionDescriptor, PsiMethod>>
      getSuperclassToFunctionsMultimap(
          @NotNull PsiMethodWrapper method,
          @NotNull BindingContext bindingContext,
          @NotNull ClassDescriptor containingClass) {
    Multimap<FqName, Pair<FunctionDescriptor, PsiMethod>> result = HashMultimap.create();

    Name functionName = Name.identifier(method.getName());
    int parameterCount = method.getParameters().size();

    for (JetType supertype : TypeUtils.getAllSupertypes(containingClass.getDefaultType())) {
      ClassifierDescriptor klass = supertype.getConstructor().getDeclarationDescriptor();
      assert klass != null;
      FqName fqName = DescriptorUtils.getFQName(klass).toSafe();

      for (FunctionDescriptor fun :
          klass.getDefaultType().getMemberScope().getFunctions(functionName)) {
        if (fun.getKind().isReal() && fun.getValueParameters().size() == parameterCount) {
          PsiElement declaration = BindingContextUtils.descriptorToDeclaration(bindingContext, fun);
          if (declaration instanceof PsiMethod) {
            result.put(fqName, Pair.create(fun, (PsiMethod) declaration));
          } // else declaration is null or JetNamedFunction: both cases are processed later
        }
      }
    }
    return result;
  }
 private static Map<ClassDescriptor, JetType> getSuperclassToSupertypeMap(
     ClassDescriptor containingClass) {
   Map<ClassDescriptor, JetType> superclassToSupertype = Maps.newHashMap();
   for (JetType supertype : TypeUtils.getAllSupertypes(containingClass.getDefaultType())) {
     ClassifierDescriptor superclass = supertype.getConstructor().getDeclarationDescriptor();
     assert superclass instanceof ClassDescriptor;
     superclassToSupertype.put((ClassDescriptor) superclass, supertype);
   }
   return superclassToSupertype;
 }
  @NotNull
  private ClassifierDescriptor modifyTypeClassifier(
      @NotNull JetType autoType, @NotNull List<TypeAndVariance> typesFromSuper) {
    ClassifierDescriptor classifier = autoType.getConstructor().getDeclarationDescriptor();
    if (!(classifier instanceof ClassDescriptor)) {
      assert classifier != null : "no declaration descriptor for type " + autoType;

      if (classifier instanceof TypeParameterDescriptor
          && autoTypeParameterToModified.containsKey(classifier)) {
        return autoTypeParameterToModified.get(classifier);
      }
      return classifier;
    }
    ClassDescriptor klass = (ClassDescriptor) classifier;

    CollectionClassMapping collectionMapping = CollectionClassMapping.getInstance();

    boolean someSupersMutable = false;
    boolean someSupersCovariantReadOnly = false;
    boolean someSupersNotCovariantReadOnly = false;
    for (TypeAndVariance typeFromSuper : typesFromSuper) {
      ClassifierDescriptor classifierFromSuper =
          typeFromSuper.type.getConstructor().getDeclarationDescriptor();
      if (classifierFromSuper instanceof ClassDescriptor) {
        ClassDescriptor classFromSuper = (ClassDescriptor) classifierFromSuper;

        if (collectionMapping.isMutableCollection(classFromSuper)) {
          someSupersMutable = true;
        } else if (collectionMapping.isReadOnlyCollection(classFromSuper)) {
          if (typeFromSuper.varianceOfPosition == Variance.OUT_VARIANCE) {
            someSupersCovariantReadOnly = true;
          } else {
            someSupersNotCovariantReadOnly = true;
          }
        }
      }
    }

    if (someSupersMutable && someSupersNotCovariantReadOnly) {
      reportError("Incompatible types in superclasses: " + typesFromSuper);
      return classifier;
    } else if (someSupersMutable) {
      if (collectionMapping.isReadOnlyCollection(klass)) {
        return collectionMapping.convertReadOnlyToMutable(klass);
      }
    } else if (someSupersNotCovariantReadOnly || someSupersCovariantReadOnly) {
      if (collectionMapping.isMutableCollection(klass)) {
        return collectionMapping.convertMutableToReadOnly(klass);
      }
    }

    ClassifierDescriptor fixed =
        PropagationHeuristics.tryToFixOverridingTWithRawType(this, typesFromSuper);
    return fixed != null ? fixed : classifier;
  }
  private boolean typeMustBeNullable(
      @NotNull JetType autoType,
      @NotNull List<TypeAndVariance> typesFromSuper,
      @NotNull TypeUsage howThisTypeIsUsed) {
    boolean someSupersNotCovariantNullable = false;
    boolean someSupersCovariantNullable = false;
    boolean someSupersNotNull = false;
    for (TypeAndVariance typeFromSuper : typesFromSuper) {
      if (!typeFromSuper.type.isNullable()) {
        someSupersNotNull = true;
      } else {
        if (typeFromSuper.varianceOfPosition == Variance.OUT_VARIANCE) {
          someSupersCovariantNullable = true;
        } else {
          someSupersNotCovariantNullable = true;
        }
      }
    }

    if (someSupersNotNull && someSupersNotCovariantNullable) {
      reportError("Incompatible types in superclasses: " + typesFromSuper);
      return autoType.isNullable();
    } else if (someSupersNotNull) {
      return false;
    } else if (someSupersNotCovariantNullable || someSupersCovariantNullable) {
      boolean annotatedAsNotNull = howThisTypeIsUsed != TYPE_ARGUMENT && !autoType.isNullable();

      if (annotatedAsNotNull && someSupersNotCovariantNullable) {
        reportError(
            "In superclass type is nullable: "
                + typesFromSuper
                + ", in subclass it is not: "
                + autoType);
        return true;
      }

      return !annotatedAsNotNull;
    }
    return autoType.isNullable();
  }
  @NotNull
  private List<TypeProjection> getTypeArgsOfType(
      @NotNull JetType autoType,
      @NotNull ClassifierDescriptor classifier,
      @NotNull List<TypeAndVariance> typesFromSuper) {
    List<TypeProjection> autoArguments = autoType.getArguments();

    if (!(classifier instanceof ClassDescriptor)) {
      assert autoArguments.isEmpty()
          : "Unexpected type arguments when type constructor is not ClassDescriptor, type = "
              + autoType;
      return autoArguments;
    }

    List<List<TypeProjectionAndVariance>> typeArgumentsFromSuper =
        calculateTypeArgumentsFromSuper((ClassDescriptor) classifier, typesFromSuper);

    // Modify type arguments using info from typesFromSuper
    List<TypeProjection> resultArguments = Lists.newArrayList();
    for (TypeParameterDescriptor parameter : classifier.getTypeConstructor().getParameters()) {
      TypeProjection argument = autoArguments.get(parameter.getIndex());

      JetType argumentType = argument.getType();
      List<TypeProjectionAndVariance> projectionsFromSuper =
          typeArgumentsFromSuper.get(parameter.getIndex());
      List<TypeAndVariance> argTypesFromSuper = getTypes(projectionsFromSuper);

      JetType type =
          modifyTypeAccordingToSuperMethods(argumentType, argTypesFromSuper, TYPE_ARGUMENT);
      Variance projectionKind =
          calculateArgumentProjectionKindFromSuper(argument, projectionsFromSuper);

      resultArguments.add(new TypeProjection(projectionKind, type));
    }
    return resultArguments;
  }
 public String toString() {
   return type.toString();
 }