Update dart2js parser to disallow repeated comparisons and prefix +.

sdk/lib/_internal/compiler/implementation/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 = "";
 
 /**
  * The messages in this file should meet the following guide lines:
@@ skipping 797 matching lines @@
 
 main() => foo(1);
 """]);
 
   static const MessageKind CONST_WITHOUT_INITIALIZER = const MessageKind(
       "Error: A constant variable must be initialized.",
       howToFix: "Try adding an initializer or "
                 "removing the 'const' modifier.",
       examples: const ["""
 void main() {
-  const c; // This constant variable must be initialized. 
+  const c; // This constant variable must be initialized.
 }"""]);
 
 
   static const MessageKind WRONG_NUMBER_OF_ARGUMENTS_FOR_ASSERT =
       const MessageKind(
           'Error: Wrong number of arguments to assert. Should be 1, but given '
           '#{argumentCount}.');
 
   static const MessageKind ASSERT_IS_GIVEN_NAMED_ARGUMENTS = const MessageKind(
       'Error: "assert" takes no named arguments, but given #{argumentCount}.');
@@ skipping 65 matching lines @@
       'Error: Library not found "#{resolvedUri}".');
 
   static const MessageKind UNSUPPORTED_EQ_EQ_EQ = const MessageKind(
       'Error: "===" is not an operator. '
       'Did you mean "#{lhs} == #{rhs}" or "identical(#{lhs}, #{rhs})"?');
 
   static const MessageKind UNSUPPORTED_BANG_EQ_EQ = const MessageKind(
       'Error: "!==" is not an operator. '
       'Did you mean "#{lhs} != #{rhs}" or "!identical(#{lhs}, #{rhs})"?');
 
+  static const MessageKind UNSUPPORTED_PREFIX_PLUS = const MessageKind(
+      'Error: "+" is not a prefix operator.');

[ahe, 2013/09/20 08:17:17]

Could you add an example and "howToFix"?

[Lasse Reichstein Nielsen, 2013/09/20 08:26:15]

What would a fix be?
For "+2" it would just be removing the "+". Any other case of using + as a
prefix is some kind of error that is hard to predict.

[ahe, 2013/09/20 08:33:42]

I think something like:

"Try removing '+'."

[ahe, 2013/09/20 08:33:42]

Another thing, please use double quotes for the complete message and single
quotes for substrings. The logic is that Google ignores single quotes in
searches.

+
   static const MessageKind UNSUPPORTED_THROW_WITHOUT_EXP = const MessageKind(
       'Error: No expression after "throw". '
       'Did you mean "rethrow"?');
 
   static const MessageKind MIRRORS_EXPECTED_STRING = const MessageKind(
       "Hint: Can't use '#{name}' here because it's an instance of '#{type}' "
       "and a 'String' value is expected.",
       howToFix: "Did you forget to add quotes?",
       examples: const [
           """
@@ skipping 364 matching lines @@
 
 class CompileTimeConstantError extends Diagnostic {
   CompileTimeConstantError(MessageKind kind, Map arguments, bool terse)
     : super(kind, arguments, terse);
 }
 
 class CompilationError extends Diagnostic {
   CompilationError(MessageKind kind, Map arguments, bool terse)
     : super(kind, arguments, terse);
 }