Require two type arguments for map literals (issue 4522).

lib/args/args.dart

 // Copyright (c) 2012, 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.
 
 /**
  * This library lets you define parsers for parsing raw command-line arguments
  * into a set of options and values using [GNU][] and [POSIX][] style options.
  *
  * ## Defining options ##
  *
@@ skipping 190 matching lines @@
   final List<String> _optionNames;
 
   /** The current argument list being parsed. Set by [parse()]. */
   List<String> _args;
 
   /** Index of the current argument being parsed in [_args]. */
   int _current;
 
   /** Creates a new ArgParser. */
   ArgParser()
-    : _options = <_Option>{},
+    : _options = <String, _Option>{},
       _optionNames = <String>[];
 
   /**
    * Defines a flag. Throws an [IllegalArgumentException] if:
    *
    * * There is already an option named [name].
    * * There is already an option using abbreviation [abbr].
    */
   void addFlag(String name, [String abbr, String help, bool defaultsTo = false,
       bool negatable = true, void callback(bool value)]) {
@@ skipping 79 matching lines @@
 
       // If we got here, the argument doesn't look like an option, so stop.
       break;
     }
 
     // Set unspecified multivalued arguments to their default value,
     // if any, and invoke the callbacks.
     for (var name in _optionNames) {
       var option = _options[name];
       if (option.allowMultiple &&
-          results[name].length == 0 && 
+          results[name].length == 0 &&
           option.defaultValue != null) {
         results[name].add(option.defaultValue);
       }
       if (option.callback != null) option.callback(results[name]);
     }
 
     // Add in the leftover arguments we didn't parse.
     return new ArgResults(results,
         _args.getRange(_current, _args.length - _current));
   }
@@ skipping 427 matching lines @@
       allowedBuffer.add(allowed);
       if (allowed == option.defaultValue) {
         allowedBuffer.add(' (default)');
       }
       first = false;
     }
     allowedBuffer.add(']');
     return allowedBuffer.toString();
   }
 }