Qualify library names in packages

lib/src/compiler/command.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.
 
 import 'dart:convert' show JSON;
 import 'dart:io';
 import 'package:args/command_runner.dart';
 import 'package:analyzer/src/generated/source.dart' show Source;
 import 'package:analyzer/src/summary/package_bundle_reader.dart'
     show InSummarySource;
 import 'compiler.dart'
     show BuildUnit, CompilerOptions, JSModuleFile, ModuleCompiler;
 import '../analyzer/context.dart' show AnalyzerOptions;
 import 'package:path/path.dart' as path;
 
 typedef void MessageHandler(Object message);
 
 /// The command for invoking the modular compiler.
 class CompileCommand extends Command {
   get name => 'compile';
   get description => 'Compile a set of Dart files into a JavaScript module.';
   final MessageHandler messageHandler;
 
   CompileCommand({MessageHandler messageHandler})
       : this.messageHandler = messageHandler ?? print {
     argParser.addOption('out', abbr: 'o', help: 'Output file (required)');
+    argParser.addOption('build-root',
+        help: '''
+Root of source files.  Generated library names are relative to this root.
+''');
     CompilerOptions.addArguments(argParser);
     AnalyzerOptions.addArguments(argParser);
   }
 
   @override
   void run() {
     var compiler =
         new ModuleCompiler(new AnalyzerOptions.fromArguments(argResults));
     var compilerOptions = new CompilerOptions.fromArguments(argResults);
     var outPath = argResults['out'];
 
     if (outPath == null) {
       usageException('Please include the output file location. For example:\n'
           '    -o PATH/TO/OUTPUT_FILE.js');
     }
-    var unit = new BuildUnit(path.basenameWithoutExtension(outPath),
+
+    var buildRoot = argResults['build-root'] as String;
+    if (buildRoot != null) {
+      buildRoot = path.absolute(buildRoot);
+    } else {
+      buildRoot = Directory.current.path;
+    }
+    var unit = new BuildUnit(path.basenameWithoutExtension(outPath), buildRoot,
         argResults.rest, _moduleForLibrary);
 
     JSModuleFile module = compiler.compile(unit, compilerOptions);
     module.errors.forEach(messageHandler);
 
     if (!module.isValid) throw new CompileErrorException();
 
     // Write JS file, as well as source map and summary (if requested).
     new File(outPath).writeAsStringSync(module.code);
     if (module.sourceMap != null) {
@@ skipping 16 matching lines @@
         'Imported file "${source.uri}" was not found as a summary or source '
         'file. Please pass in either the summary or the source file '
         'for this import.');
   }
 }
 
 /// Thrown when the input source code has errors.
 class CompileErrorException implements Exception {
   toString() => '\nPlease fix all errors before compiling (warnings are okay).';
 }