fix writing summaries

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:io';
 import 'package:analyzer/src/generated/source.dart' show Source;
 import 'package:analyzer/src/summary/package_bundle_reader.dart'
     show InSummarySource;
 import 'package:args/args.dart' show ArgParser, ArgResults;
 import 'package:args/command_runner.dart' show UsageException;
@@ skipping 85 matching lines @@
   if (outPaths.isEmpty) {
     _usageException('Please include the output file location. For example:\n'
         '    -o PATH/TO/OUTPUT_FILE.js');
   } else if (outPaths.length != moduleFormats.length) {
     _usageException('Number of output files (${outPaths.length}) must match '
         'number of module formats (${moduleFormats.length}).');
   }
 
   // TODO(jmesserly): for now the first one is special. This will go away once
   // we've removed the "root" and "module name" variables.
-  var outPath = outPaths[0];
+  var firstOutPath = outPaths[0];
 
   var libraryRoot = argResults['library-root'] as String;
   libraryRoot ??= argResults['build-root'] as String;
   if (libraryRoot != null) {
     libraryRoot = path.absolute(libraryRoot);
   } else {
     libraryRoot = Directory.current.path;
   }
   var moduleRoot = argResults['module-root'] as String;
   String modulePath;
   if (moduleRoot != null) {
     moduleRoot = path.absolute(moduleRoot);
-    if (!path.isWithin(moduleRoot, outPath)) {
-      _usageException('Output file $outPath must be within the module root '
-          'directory $moduleRoot');
+    if (!path.isWithin(moduleRoot, firstOutPath)) {
+      _usageException('Output file $firstOutPath must be within the module '
+          'root directory $moduleRoot');
     }
     modulePath =
-        path.withoutExtension(path.relative(outPath, from: moduleRoot));
+        path.withoutExtension(path.relative(firstOutPath, from: moduleRoot));
   } else {
-    moduleRoot = path.dirname(outPath);
-    modulePath = path.basenameWithoutExtension(outPath);
+    moduleRoot = path.dirname(firstOutPath);
+    modulePath = path.basenameWithoutExtension(firstOutPath);
   }
 
   var unit = new BuildUnit(modulePath, libraryRoot, argResults.rest,
       (source) => _moduleForLibrary(moduleRoot, source, compilerOpts));
 
-  JSModuleFile module = compiler.compile(unit, compilerOpts);
+  var module = compiler.compile(unit, compilerOpts);
   module.errors.forEach(printFn);
 
   if (!module.isValid) throw new CompileErrorException();
 
   // Write JS file, as well as source map and summary (if requested).
   for (var i = 0; i < outPaths.length; i++) {
-    module.writeCodeSync(moduleFormats[i], outPaths[i]);
+    var outPath = outPaths[i];
+    module.writeCodeSync(moduleFormats[i], outPath);
     if (module.summaryBytes != null) {
       var summaryPath =
           path.withoutExtension(outPath) + '.${compilerOpts.summaryExtension}';
       new File(summaryPath).writeAsBytesSync(module.summaryBytes);
     }
   }
-
 }
 
 String _moduleForLibrary(
     String moduleRoot, Source source, CompilerOptions compilerOpts) {
   if (source is InSummarySource) {
     var summaryPath = source.summaryPath;
     var ext = '.${compilerOpts.summaryExtension}';
     if (path.isWithin(moduleRoot, summaryPath) && summaryPath.endsWith(ext)) {
       var buildUnitPath =
           summaryPath.substring(0, summaryPath.length - ext.length);
@@ skipping 16 matching lines @@
     '\n\n${_argParser.usage}';
 
 void _usageException(String message) {
   throw new UsageException(message, _usageMessage);
 }
 
 /// Thrown when the input source code has errors.
 class CompileErrorException implements Exception {
   toString() => '\nPlease fix all errors before compiling (warnings are okay).';
 }