Report CompileTimeErrorCode.DUPLICATE_PART when not only URI, but even Source is the same.

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';
 import 'package:analyzer/src/dart/element/element.dart';
 
 /**
@@ skipping 736 matching lines @@
    * Parameters:
    * 0: the name of the duplicate entity
    */
   static const CompileTimeErrorCode DUPLICATE_DEFINITION =
       const CompileTimeErrorCode(
           'DUPLICATE_DEFINITION', "The name '{0}' is already defined");
 
   /**
    * 18.3 Parts: It's a compile-time error if the same library contains two part
    * directives with the same URI.
-   *
-   * Parameters:
-   * 0: the URI of the duplicate part
    */
-  static const CompileTimeErrorCode DUPLICATE_PART = const CompileTimeErrorCode(
-      'DUPLICATE_PART',
-      "The library already contains a part with the uri '{0}'.");
+  static const CompileTimeErrorCode DUPLICATE_PART =
+      const CompileTimeErrorCode('DUPLICATE_PART', 'Duplicate part');

[Brian Wilkerson, 2016/10/06 22:14:11]

I think the old message was better. I think it would be fine if the URI we use
for the message was the resolved URI rather than the string literal from the
directive.

 
   /**
    * 7. Classes: It is a compile-time error if a class has an instance member
    * and a static member with the same name.
    *
    * This covers the additional duplicate definition cases where inheritance has
    * to be considered.
    *
    * Parameters:
    * 0: the name of the class that has conflicting instance/static members
@@ skipping 4102 matching lines @@
    * Initialize a newly created error code to have the given [name].
    */
   const TodoCode(String name) : super(name, "{0}");
 
   @override
   ErrorSeverity get errorSeverity => ErrorSeverity.INFO;
 
   @override
   ErrorType get type => ErrorType.TODO;
 }