Support new import rules.

sdk/lib/_internal/compiler/implementation/warnings.dart

Index: sdk/lib/_internal/compiler/implementation/warnings.dart
diff --git a/sdk/lib/_internal/compiler/implementation/warnings.dart b/sdk/lib/_internal/compiler/implementation/warnings.dart
index b55b0260f8c9119bd7be78b587d3f1e44eabf6f2..5bebf7a6e7a49818f6e03309e31aaaf9c9071d25 100644
--- a/sdk/lib/_internal/compiler/implementation/warnings.dart
+++ b/sdk/lib/_internal/compiler/implementation/warnings.dart
@@ -75,9 +75,15 @@ class MessageKind {
   /// Should describe how to fix the problem. Elided when using --terse option.
   final String howToFix;
 
-  /// Examples will be checked by
-  /// tests/compiler/dart2js/message_kind_test.dart.
-  final List<String> examples;
+  /**
+   *  Examples will be checked by
+   *  tests/compiler/dart2js/message_kind_test.dart.
+   *
+   *  An example is either a String containing the example source code or a Map
+   *  from filenames to source code. In the latter case, the filename for the
+   *  main library code must be 'main.dart'.
+   */
+  final List examples;
 
   const MessageKind(this.template, {this.howToFix, this.examples});
 
@@ -188,6 +194,39 @@ class MessageKind {
       error: const MessageKind('Error: Duplicate import of "#{name}".'),
       warning: const MessageKind('Warning: Duplicate import of "#{name}".'));
 
+  static const MessageKind HIDDEN_IMPORT = const MessageKind(
+      "Warning: '#{name}' from library '#{hiddenUri}' by '#{name}' "
+      "from library '#{hidingUri}'.",
+      howToFix: "Try adding 'hide #{name}' to the import of '#{hiddenUri}'.",
+      examples: const [
+          const {'main.dart': """

[ahe, 2013/09/17 10:47:18]

I think these examples would be easier to read if they were formatted
differently. In particular if the filename is always on a line by itself.

[Johnni Winther, 2013/09/18 06:14:11]

Done.

+import 'dart:async'; // This imports a class Future.
+import 'future.dart';
+
+void main() {}""", 'future.dart': """

[ahe, 2013/09/17 10:47:18]

This is somewhat hard to read. Also, please add a newline at the end of the
example.

[Johnni Winther, 2013/09/18 06:14:11]

Done.

+library future;
+
+class Future {}"""},
+          const {'main.dart': """
+import 'future.dart';
+import 'dart:async'; // This imports a class Future.
+
+void main() {}""", 'future.dart': """
+library future;
+
+class Future {}"""},
+          const {'main.dart': """
+import 'export.dart';
+import 'dart:async'; // This imports a class Future.
+
+void main() {}""", 'future.dart': """
+library future;
+
+class Future {}""", 'export.dart': """
+library export;
+
+export 'future.dart';"""}]);
+
   static const MessageKind DUPLICATE_EXPORT = const MessageKind(
       'Error: Duplicate export of "#{name}".');