Better hints for await in non-async functions

pkg/compiler/lib/src/warnings.dart

 // Copyright (c) 2011, 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.
 
 part of dart2js;
 
 const DONT_KNOW_HOW_TO_FIX = "Computer says no!";
 
 /**
  * The messages in this file should meet the following guide lines:
@@ skipping 103 matching lines @@
 
   static const MessageKind ADDITIONAL_ARGUMENT = const MessageKind(
       "Additional argument.");
 
   static const MessageKind NAMED_ARGUMENT_NOT_FOUND = const MessageKind(
       "No named argument '#{argumentName}' found on method.");
 
   static const MessageKind MEMBER_NOT_FOUND = const MessageKind(
       "No member named '#{memberName}' in class '#{className}'.");
 
+  static const MessageKind AWAIT_MEMBER_NOT_FOUND = const MessageKind(
+      "No member named 'await' in class '#{className}'.",
+      howToFix: "Did you mean to add the 'async' marker "
+                "to #{enclosingFunctionText}?",
+      examples: const ["""
+class A {
+  m() => await -3;
+}
+main() => new A().m();
+""", """
+class A {
+  m() => () => await -3;
+}
+main() => new A().m();
+"""]);
+
   static const MessageKind METHOD_NOT_FOUND = const MessageKind(
       "No method named '#{memberName}' in class '#{className}'.");
 
   static const MessageKind OPERATOR_NOT_FOUND = const MessageKind(
       "No operator '#{memberName}' in class '#{className}'.");
 
   static const MessageKind SETTER_NOT_FOUND = const MessageKind(
       "No setter named '#{memberName}' in class '#{className}'.");
 
   static const MessageKind GETTER_NOT_FOUND = const MessageKind(
@@ skipping 14 matching lines @@
 
   static const MessageKind THIS_IS_THE_DECLARATION = const MessageKind(
       "This is the declaration of '#{name}'.");
 
   static const MessageKind THIS_IS_THE_METHOD = const MessageKind(
       "This is the method declaration.");
 
   static const MessageKind CANNOT_RESOLVE = const MessageKind(
       "Cannot resolve '#{name}'.");
 
+  static const MessageKind CANNOT_RESOLVE_AWAIT = const MessageKind(
+      "Cannot resolve '#{name}'.",
+      howToFix: "Did you mean to add the 'async' marker "
+                "to #{enclosingFunctionText}?",
+      examples: const [
+          "main() => await -3;",
+          "main() { (() => await -3)(); }",
+          "foo() => await -3; main() => foo();"
+      ]);
+
   static const MessageKind CANNOT_RESOLVE_IN_INITIALIZER = const MessageKind(
       "Cannot resolve '#{name}'. It would be implicitly looked up on this "
       "instance, but instances are not available in initializers.",
       howToFix: "Try correcting the unresolved reference or move the "
           "initialization to a constructor body.",
       examples: const ["""
 class A {
   var test = unresolvedName;
 }
 main() => new A();
@@ skipping 2331 matching lines @@
   static String convertToString(value) {
     if (value is ErrorToken) {
       // Shouldn't happen.
       return value.assertionMessage;
     } else if (value is Token) {
       value = value.value;
     }
     return '$value';
   }
 }