/**
   * Infer the parameter and return types of a function from the parameter and return types of the
   * function it is overriding.
   *
   * @param oldType The function being overridden. Does nothing if this is null.
   * @param paramsParent The LP node of the function that we're assigning to. If null, that just
   *     means we're not initializing this to a function literal.
   */
  FunctionTypeBuilder inferFromOverriddenFunction(
      @Nullable FunctionType oldType, @Nullable Node paramsParent) {
    if (oldType == null) {
      return this;
    }

    returnType = oldType.getReturnType();
    returnTypeInferred = oldType.isReturnTypeInferred();
    if (paramsParent == null) {
      // Not a function literal.
      parametersNode = oldType.getParametersNode();
      if (parametersNode == null) {
        parametersNode = new FunctionParamBuilder(typeRegistry).build();
      }
    } else {
      // We're overriding with a function literal. Apply type information
      // to each parameter of the literal.
      FunctionParamBuilder paramBuilder = new FunctionParamBuilder(typeRegistry);
      Iterator<Node> oldParams = oldType.getParameters().iterator();
      boolean warnedAboutArgList = false;
      boolean oldParamsListHitOptArgs = false;
      for (Node currentParam = paramsParent.getFirstChild();
          currentParam != null;
          currentParam = currentParam.getNext()) {
        if (oldParams.hasNext()) {
          Node oldParam = oldParams.next();
          Node newParam = paramBuilder.newParameterFromNode(oldParam);

          oldParamsListHitOptArgs =
              oldParamsListHitOptArgs || oldParam.isVarArgs() || oldParam.isOptionalArg();

          // The subclass method might right its var_args as individual
          // arguments.
          if (currentParam.getNext() != null && newParam.isVarArgs()) {
            newParam.setVarArgs(false);
            newParam.setOptionalArg(true);
          }
        } else {
          warnedAboutArgList |=
              addParameter(
                  paramBuilder,
                  typeRegistry.getNativeType(UNKNOWN_TYPE),
                  warnedAboutArgList,
                  codingConvention.isOptionalParameter(currentParam) || oldParamsListHitOptArgs,
                  codingConvention.isVarArgsParameter(currentParam));
        }
      }
      parametersNode = paramBuilder.build();
    }
    return this;
  }
  /** @param fnNode A node for a function for which to generate a type annotation */
  private String getFunctionAnnotation(Node fnNode) {
    Preconditions.checkState(fnNode.isFunction());
    StringBuilder sb = new StringBuilder("/**\n");

    JSType type = fnNode.getJSType();

    if (type == null || type.isUnknownType()) {
      return "";
    }

    FunctionType funType = type.toMaybeFunctionType();

    // We need to use the child nodes of the function as the nodes for the
    // parameters of the function type do not have the real parameter names.
    // FUNCTION
    //   NAME
    //   LP
    //     NAME param1
    //     NAME param2
    if (fnNode != null) {
      Node paramNode = NodeUtil.getFunctionParameters(fnNode).getFirstChild();

      // Param types
      for (Node n : funType.getParameters()) {
        // Bail out if the paramNode is not there.
        if (paramNode == null) {
          break;
        }
        sb.append(" * ");
        appendAnnotation(sb, "param", getParameterNodeJSDocType(n));
        sb.append(" ").append(paramNode.getString()).append("\n");
        paramNode = paramNode.getNext();
      }
    }

    // Return type
    JSType retType = funType.getReturnType();
    if (retType != null && !retType.isUnknownType() && !retType.isEmptyType()) {
      sb.append(" * ");
      appendAnnotation(sb, "return", retType.toAnnotationString());
      sb.append("\n");
    }

    // Constructor/interface
    if (funType.isConstructor() || funType.isInterface()) {

      FunctionType superConstructor = funType.getSuperClassConstructor();

      if (superConstructor != null) {
        ObjectType superInstance = funType.getSuperClassConstructor().getInstanceType();
        if (!superInstance.toString().equals("Object")) {
          sb.append(" * ");
          appendAnnotation(sb, "extends", superInstance.toAnnotationString());
          sb.append("\n");
        }
      }

      if (funType.isInterface()) {
        for (ObjectType interfaceType : funType.getExtendedInterfaces()) {
          sb.append(" * ");
          appendAnnotation(sb, "extends", interfaceType.toAnnotationString());
          sb.append("\n");
        }
      }

      // Avoid duplicates, add implemented type to a set first
      Set<String> interfaces = Sets.newTreeSet();
      for (ObjectType interfaze : funType.getImplementedInterfaces()) {
        interfaces.add(interfaze.toAnnotationString());
      }
      for (String interfaze : interfaces) {
        sb.append(" * ");
        appendAnnotation(sb, "implements", interfaze);
        sb.append("\n");
      }

      if (funType.isConstructor()) {
        sb.append(" * @constructor\n");
      } else if (funType.isInterface()) {
        sb.append(" * @interface\n");
      }
    }

    if (fnNode != null && fnNode.getBooleanProp(Node.IS_DISPATCHER)) {
      sb.append(" * @javadispatch\n");
    }

    sb.append(" */\n");
    return sb.toString();
  }