DDC: mostly incremental compilation, fixes #223

tool/patch_sdk.dart

 #!/usr/bin/env dart
 // Copyright (c) 2015, 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 tool to merge the SDK libraries and our patch files.
 /// This is currently designed as an offline tool, but we could automate it.
 library dev_compiler.tool.patch_sdk;
 
 import 'dart:io';
 import 'dart:math' as math;
 
 import 'package:analyzer/analyzer.dart';
 import 'package:analyzer/src/generated/sdk.dart';
 import 'package:path/path.dart' as path;
 
 void main(List<String> argv) {
+  var self = path.relative(path.fromUri(Platform.script));
   if (argv.length < 2) {
-    var self = path.relative(path.fromUri(Platform.script));
     var toolDir = path.relative(path.dirname(path.fromUri(Platform.script)));
 
     var inputExample = path.join(toolDir, 'input_sdk');
     var outExample = path.relative(
         path.normalize(path.join(toolDir, '..', 'test', 'generated_sdk')));
 
     print('Usage: $self INPUT_DIR OUTPUT_DIR');
     print('For example:');
     print('\$ $self $inputExample $outExample');
 
     inputExample = path.join(toolDir, 'min_sdk');
     outExample = path.join(toolDir, 'out', 'min_sdk');
     print('\$ $self $inputExample $outExample');
     exit(1);
   }
+  var selfLastModify = new File(self).lastModifiedSync().millisecondsSinceEpoch;
 
   var input = argv[0];
   var sdkLibIn = path.join(input, 'lib');
   var patchIn = path.join(input, 'patch');
   var privateIn = path.join(input, 'private');
   var sdkOut = path.join(argv[1], 'lib');
 
   var INTERNAL_PATH = '_internal/compiler/js_lib/';
 
   // Copy libraries.dart and version
@@ skipping 50 matching lines @@
       var patchPath = path.join(
           patchIn, path.basenameWithoutExtension(libraryIn) + '_patch.dart');
 
       var patchFile = new File(patchPath);
       bool patchExists = patchFile.existsSync();
       if (patchExists) {
         inputModifyTime = math.max(inputModifyTime,
             patchFile.lastModifiedSync().millisecondsSinceEpoch);
       }
 
+      // If the patch_sdk itself was modified, take that into account.
+      inputModifyTime = math.max(inputModifyTime, selfLastModify);
+
       // Compute output paths
       outPaths = outPaths
           .map((p) => path.join(sdkOut, path.relative(p, from: sdkLibIn)))
           .toList();
 
       // Compare output modify time with input modify time.
       bool needsUpdate = false;
       for (var outPath in outPaths) {
         var outFile = new File(outPath);
         if (!outFile.existsSync() ||
@@ skipping 309 matching lines @@
     if (diff != 0) return diff;
     return end - other.end;
   }
 }
 
 List<SdkLibrary> _getSdkLibraries(String contents) {
   var libraryBuilder = new SdkLibrariesReader_LibraryBuilder(true);
   parseCompilationUnit(contents).accept(libraryBuilder);
   return libraryBuilder.librariesMap.sdkLibraries;
 }