Add a hint to rename .analysis_options files.

pkg/analyzer/lib/src/analysis_options/error/option_codes.dart

 // Copyright (c) 2014, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 library analyzer.src.analysis_options.error.option_codes;
 
 import 'package:analyzer/error/error.dart';
 
 /**
  * The error codes used for errors in analysis options files. The convention for
@@ skipping 132 matching lines @@
   const AnalysisOptionsWarningCode(String name, String message,
       [String correction])
       : super(name, message, correction);
 
   @override
   ErrorSeverity get errorSeverity => ErrorSeverity.WARNING;
 
   @override
   ErrorType get type => ErrorType.STATIC_WARNING;
 }
+
+class AnalysisOptionsHintCode extends ErrorCode {
+  /**
+   * An error code indicating the analysis options file name is deprecated and
+   * the file should be renamed.
+   *
+   * Parameters:
+   * 0: the uri of the file which should be renamed
+   */
+  static const ErrorCode DEPRECATED_ANALYSIS_OPTIONS_FILE_NAME =
+      const AnalysisOptionsHintCode(
+          'DEPRECATED_ANALYSIS_OPTIONS_FILE_NAME',
+          "The name of the analysis options file {0} is deprecated;"
+          " consider renaming it to analysis_options.yaml.");
+
+  /**
+   * Initialize a newly created hint code to have the given [name].
+   */
+  const AnalysisOptionsHintCode(String name, String message,
+      [String correction])
+      : super(name, message, correction);
+
+  @override
+  ErrorSeverity get errorSeverity => ErrorSeverity.INFO;
+
+  @override
+  ErrorType get type => ErrorType.HINT;
+}