fixes #610, incorrect help output

bin/dartdevc.dart

 #!/usr/bin/env dart
 // Copyright (c) 2016, 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.
 
 /// Command line entry point for Dart Development Compiler (dartdevc).
 ///
 /// Supported commands are
 ///   * compile: builds a collection of dart libraries into a single JS module
 ///
@@ skipping 20 matching lines @@
 /// * We didn't have a file watcher API at first,
 /// * We had no conventions about where compiled output should go (or even
 ///   that we would be compiling at all, vs running on an in-browser Dart VM),
 /// * We wanted a good first impression with our simple examples, so we used
 ///   local file servers, and users have an expectation of it now, even though
 ///   it doesn't scale to typical apps that need their own real servers.
 
 import 'dart:async';
 import 'dart:io';
 import 'package:analyzer/src/generated/engine.dart' show AnalysisEngine;
-import 'package:args/command_runner.dart';
 import 'package:bazel_worker/bazel_worker.dart';
 import 'package:dev_compiler/src/compiler/command.dart';
 
 Future main(List<String> args) async {
   // Always returns a new modifiable list.
   args = _preprocessArgs(args);
 
   if (args.contains('--persistent_worker')) {
     new _CompilerWorker(args..remove('--persistent_worker')).run();
   } else {
-    exitCode = await _runCommand(args);
+    exitCode = compile(args);
   }
 }
 
-/// Runs a single compile command, and returns an exit code.
-Future<int> _runCommand(List<String> args,
-    {MessageHandler messageHandler}) async {
-  try {
-    if (args.isEmpty || args.first != 'compile' && args.first != 'help') {
-      // TODO(jmesserly): we should deprecate the commands. For now they are
-      // still supported for backwards compatibility.
-      args.insert(0, 'compile');
-    }
-    var runner = new CommandRunner('dartdevc', 'Dart Development Compiler');
-    runner.addCommand(new CompileCommand(messageHandler: messageHandler));
-    await runner.run(args);
-  } catch (e, s) {
-    return _handleError(e, s, args, messageHandler: messageHandler);
-  }
-  return EXIT_CODE_OK;
-}
-
 /// Runs the compiler worker loop.
 class _CompilerWorker extends AsyncWorkerLoop {
   /// The original args supplied to the executable.
   final List<String> _startupArgs;
 
   _CompilerWorker(this._startupArgs) : super();
 
   /// Performs each individual work request.
   Future<WorkResponse> performRequest(WorkRequest request) async {
     var args = _startupArgs.toList()..addAll(request.arguments);
 
     var output = new StringBuffer();
-    var exitCode = await _runCommand(args, messageHandler: output.writeln);
+    var exitCode = compile(args, printFn: output.writeln);
     AnalysisEngine.instance.clearCaches();
     return new WorkResponse()
       ..exitCode = exitCode
       ..output = output.toString();
   }
 }
 
-/// Handles [error] in a uniform fashion. Returns the proper exit code and calls
-/// [messageHandler] with messages.
-int _handleError(dynamic error, dynamic stackTrace, List<String> args,
-    {MessageHandler messageHandler}) {
-  messageHandler ??= print;
-
-  if (error is UsageException) {
-    // Incorrect usage, input file not found, etc.
-    messageHandler(error);
-    return 64;
-  } else if (error is CompileErrorException) {
-    // Code has error(s) and failed to compile.
-    messageHandler(error);
-    return 1;
-  } else {
-    // Anything else is likely a compiler bug.
-    //
-    // --unsafe-force-compile is a bit of a grey area, but it's nice not to
-    // crash while compiling
-    // (of course, output code may crash, if it had errors).
-    //
-    messageHandler("");
-    messageHandler("We're sorry, you've found a bug in our compiler.");
-    messageHandler("You can report this bug at:");
-    messageHandler("    https://github.com/dart-lang/dev_compiler/issues");
-    messageHandler("");
-    messageHandler(
-        "Please include the information below in your report, along with");
-    messageHandler(
-        "any other information that may help us track it down. Thanks!");
-    messageHandler("");
-    messageHandler("    dartdevc arguments: " + args.join(' '));
-    messageHandler("    dart --version: ${Platform.version}");
-    messageHandler("");
-    messageHandler("```");
-    messageHandler(error);
-    messageHandler(stackTrace);
-    messageHandler("```");
-    return 70;
-  }
-}
-
 /// Always returns a new modifiable list.
 ///
 /// If the final arg is `@file_path` then read in all the lines of that file
 /// and add those as args.
 ///
 /// Bazel actions that support workers must provide all their per-WorkRequest
 /// arguments in a file like this instead of as normal args.
 List<String> _preprocessArgs(List<String> args) {
   args = new List.from(args);
   if (args.isNotEmpty && args.last.startsWith('@')) {
     var fileArg = args.removeLast();
     args.addAll(new File(fileArg.substring(1)).readAsLinesSync());
   }
   return args;
 }