Report an error when a part-of refers to an unnamed library.

pkg/analyzer/lib/src/error/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.error.codes;
 
 import 'package:analyzer/error/error.dart';
 
 export 'package:analyzer/src/analysis_options/error/option_codes.dart';
 export 'package:analyzer/src/dart/error/hint_codes.dart';
@@ skipping 4402 matching lines @@
    * 1: the non-matching actual library name from the "part of" declaration
    */
   static const StaticWarningCode PART_OF_DIFFERENT_LIBRARY =
       const StaticWarningCode(
           'PART_OF_DIFFERENT_LIBRARY',
           "Expected this library to be part of '{0}', not '{1}'.",
           "Try including a different part, or "
           "changing the name of the library in the part's part-of directive.");
 
   /**
+   * Parts: It is a static warning if the referenced part declaration
+   * <i>p</i> names a library that does not have a library tag.
+   *
+   * Parameters:
+   * 0: the URI of the expected library
+   * 1: the non-matching actual library name from the "part of" declaration
+   */
+  static const StaticWarningCode PART_OF_UNNAMED_LIBRARY =
+      const StaticWarningCode(
+          'PART_OF_UNNAMED_LIBRARY',
+          "Library is unnamed. Expected a URI not a library name '{0}' in the "
+          "part-of directive.",
+          "Try changing the part-of directive to a URI, or try including a"
+          " different part.");
+
+  /**
    * 7.6.2 Factories: It is a static warning if the function type of <i>k'</i>
    * is not a subtype of the type of <i>k</i>.
    *
    * Parameters:
    * 0: the name of the redirected constructor
    * 1: the name of the redirecting constructor
    */
   static const StaticWarningCode REDIRECT_TO_INVALID_FUNCTION_TYPE =
       const StaticWarningCode(
           'REDIRECT_TO_INVALID_FUNCTION_TYPE',
@@ skipping 630 matching lines @@
    * created from the optional [correction] template.
    */
   const StrongModeCode(ErrorType type, String name, String message,
       [String correction])
       : type = type,
         super('STRONG_MODE_$name', message, correction);
 
   @override
   ErrorSeverity get errorSeverity => type.severity;
 }