Add bazel worker support to the dev compiler.

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 22 matching lines @@
 ///   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:io';
 import 'package:args/command_runner.dart';
 import 'package:dev_compiler/src/compiler/command.dart';
 
 main(List<String> args) async {
+  args = _preprocessArgs(args);
+
   var runner = new CommandRunner('dartdevc', 'Dart Development Compiler');
   runner.addCommand(new CompileCommand());
   try {
     await runner.run(args);
   } on UsageException catch (e) {
     // Incorrect usage, input file not found, etc.
     print(e);
     exit(64);
   } on CompileErrorException catch (e) {
     // Code has error(s) and failed to compile.
@@ skipping 16 matching lines @@
     print("");
     print("    dartdevc arguments: " + args.join(' '));
     print("    dart --version: ${Platform.version}");
     print("");
     print("```");
     print(e);
     print(s);
     print("```");
   }
 }
+
+/// If the final arg is `@file_path` then read in all the lines of that file
+/// and add those as args.

[Jennifer Messerly, 2016/04/14 21:02:14]

add a comment that this is required by Bazel workers?

[jakemac, 2016/04/14 21:48:25]

Done.

+List<String> _preprocessArgs(List<String> args) {
+  if (args.last.startsWith('@')) {
+    return new List.from(args)
+      ..addAll(new File(args.last.substring(1)).readAsLinesSync());
+  } else {
+    return args;
+  }
+}