Add support for building patched_sdk and platform.dill for dart2js:

tools/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.
 
 import 'dart:io';
 import 'dart:isolate' show RawReceivePort;
@@ skipping 34 matching lines @@
 
 Future main(List<String> argv) async {
   var port = new RawReceivePort();
   try {
     await _main(argv);
   } finally {
     port.close();
   }
 }
 
-Future _main(List<String> argv) async {
+void usage(String mode) {

[Vyacheslav Egorov (Google), 2017/04/27 14:07:23]

mode is not used in the body of this function

[Siggi Cherem (dart-lang), 2017/04/28 21:37:21]

oops. Done.

+  var base = path.fromUri(Platform.script);
+  final self = path.relative(base);
+  print('Usage: $self [vm|dart2js] SDK_DIR PATCH_DIR OUTPUT_DIR PACKAGES');
+
+  final repositoryDir = path.relative(path.dirname(path.dirname(base)));
+  final sdkExample = path.relative(path.join(repositoryDir, 'sdk'));
+  final patchExample = path.relative(
+      path.join(repositoryDir, 'out', 'DebugX64', 'obj', 'gen', 'patch'));
+  final outExample = path.relative(
+      path.join(repositoryDir, 'out', 'DebugX64', 'obj', 'gen', 'patched_sdk'));
+  final packagesExample = path.relative(path.join(repositoryDir, '.packages'));
+  print('For example:');
+  print('\$ $self vm $sdkExample $patchExample $outExample $packagesExample');
+
+  exit(1);
+}
+
+Future _main(List<String> argv) {
+  var mode = argv.first;
+  if (mode == 'vm') return _vmMain(argv);
+  if (mode == 'dart2js') return _dart2jsMain(argv);
+  usage('[vm|dart2js]');
+  return null;
+}
+
+Future _vmMain(List<String> argv) async {

[Vyacheslav Egorov (Google), 2017/04/27 14:07:23]

vmMain and dart2jsMain have very similar prefix and suffix. We should consider
splitting as much shared parts out as possible.

[Siggi Cherem (dart-lang), 2017/04/28 21:37:21]

Done.

   var base = path.fromUri(Platform.script);
   var dartDir = path.dirname(path.dirname(path.absolute(base)));
-
   if (argv.length != 5 || argv.first != 'vm') {

[Vyacheslav Egorov (Google), 2017/04/27 14:07:23]

argv.first != 'vm' can't happen anymore. 

[Siggi Cherem (dart-lang), 2017/04/28 21:37:21]

Done.

-    final self = path.relative(base);
-    print('Usage: $self vm SDK_DIR PATCH_DIR OUTPUT_DIR PACKAGES');
-
-    final repositoryDir = path.relative(path.dirname(path.dirname(base)));
-    final sdkExample = path.relative(path.join(repositoryDir, 'sdk'));
-    final patchExample = path.relative(
-        path.join(repositoryDir, 'out', 'DebugX64', 'obj', 'gen', 'patch'));
-    final outExample = path.relative(path.join(
-        repositoryDir, 'out', 'DebugX64', 'obj', 'gen', 'patched_sdk'));
-    print('For example:');
-    print('\$ $self vm $sdkExample $patchExample $outExample');
-
-    exit(1);
+    usage('vm');
   }
 
-  var mode = argv[0];
-  assert(mode == "vm");
   var input = argv[1];
   var sdkLibIn = path.join(input, 'lib');
   var patchIn = argv[2];
   var outDir = argv[3];
   var sdkOut = path.join(outDir, 'lib');
   var packagesFile = argv[4];
 
   // Copy and patch libraries.dart and version
   var libContents = readInputFile(path.join(
       sdkLibIn, '_internal', 'sdk_library_metadata', 'lib', 'libraries.dart'));
@@ skipping 32 matching lines @@
       libContents);
 
   // Parse libraries.dart
   var sdkLibraries = _getSdkLibraries(libContents);
 
   // Enumerate core libraries and apply patches
   for (SdkLibrary library in sdkLibraries) {
     if (library.isDart2JsLibrary) {
       continue;
     }
-
-    var libraryOut = path.join(sdkLibIn, library.path);
-    var libraryIn = libraryOut;
-
-    var libraryFile = getInputFile(libraryIn, canBeMissing: true);
-    if (libraryFile != null) {
-      var outPaths = <String>[libraryOut];
-      var libraryContents = libraryFile.readAsStringSync();
-
-      int inputModifyTime =
-          libraryFile.lastModifiedSync().millisecondsSinceEpoch;
-      var partFiles = <File>[];
-      for (var part in parseDirectives(libraryContents).directives) {
-        if (part is PartDirective) {
-          var partPath = part.uri.stringValue;
-          outPaths.add(path.join(path.dirname(libraryOut), partPath));
-
-          var partFile =
-              getInputFile(path.join(path.dirname(libraryIn), partPath));
-          partFiles.add(partFile);
-          inputModifyTime = math.max(inputModifyTime,
-              partFile.lastModifiedSync().millisecondsSinceEpoch);
-        }
-      }
-
-      // See if we can find a patch file.
-      var patchPath = path.join(
-          patchIn, path.basenameWithoutExtension(libraryIn) + '_patch.dart');
-
-      var patchFile = getInputFile(patchPath, canBeMissing: true);
-      if (patchFile != null) {
-        inputModifyTime = math.max(inputModifyTime,
-            patchFile.lastModifiedSync().millisecondsSinceEpoch);
-      }
-
-      // 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() ||
-            outFile.lastModifiedSync().millisecondsSinceEpoch <
-                inputModifyTime) {
-          needsUpdate = true;
-          break;
-        }
-      }
-
-      if (needsUpdate) {
-        var contents = <String>[libraryContents];
-        contents.addAll(partFiles.map((f) => f.readAsStringSync()));
-        if (patchFile != null) {
-          var patchContents = patchFile.readAsStringSync();
-          contents = _patchLibrary(patchFile.path, contents, patchContents);
-        }
-
-        for (var i = 0; i < outPaths.length; i++) {
-          _writeSync(outPaths[i], contents[i]);
-        }
-      }
-    }
+    _applyPatch(library, sdkLibIn, patchIn, sdkOut);
   }
 
   for (var tuple in [
     ['_builtin', 'builtin.dart']
   ]) {
     var vmLibrary = tuple[0];
     var dartFile = tuple[1];
 
     // The "dart:_builtin" library is only available for the DartVM.
     var builtinLibraryIn = path.join(dartDir, 'runtime', 'bin', dartFile);
@@ skipping 20 matching lines @@
   await writeDepsFile(Platform.script,
       Uri.base.resolveUri(new Uri.file("$outDir.d")), platformFinalLocation,
       packages: packages,
       platform: platform,
       extraDependencies: deps,
       verbose: false);
 
   await new File.fromUri(platform).rename(platformFinalLocation.toFilePath());
 }
 
+Future _dart2jsMain(List<String> argv) async {
+  if (argv.length != 5 || argv.first != 'dart2js') {
+    usage('dart2js');
+  }
+
+  var input = argv[1];
+  var sdkLibIn = path.join(input, 'lib');
+  var patchIn = argv[2];
+  var outDir = argv[3];
+  var sdkOut = path.join(outDir, 'lib');
+  var packagesFile = argv[4];
+
+  // Parse libraries.dart
+  var libContents = readInputFile(path.join(
+      sdkLibIn, '_internal', 'sdk_library_metadata', 'lib', 'libraries.dart'));
+  var sdkLibraries = _getSdkLibraries(libContents);
+
+  // Enumerate core libraries and apply patches
+  for (SdkLibrary library in sdkLibraries) {
+    if (library.isVmLibrary) continue;
+    _applyPatch(library, sdkLibIn, patchIn, sdkOut);
+  }
+
+  Uri platform = Uri.base
+      .resolveUri(new Uri.directory(outDir).resolve('platform.dill.tmp'));
+  Uri packages = Uri.base.resolveUri(new Uri.file(packagesFile));
+  await compilePlatform(
+      Uri.base.resolveUri(new Uri.directory(outDir)), platform,
+      packages: packages, verbose: false, targetDart2js: true);
+
+  Uri platformFinalLocation =
+      Uri.base.resolveUri(new Uri.directory(outDir).resolve('platform.dill'));
+
+  // To properly regenerate the patched_dart2js_sdk and platform.dill only when
+  // necessary, we track dependencies as follows:
+  //  - inputs like the sdk libraries and dart2js patch files are covered by the
+  //  extraDependencies argument.
+  //  - this script and its script dependencies are handled by writeDepsFile.
+  //  - the internal platform libraries that may affect how this script
+  //  runs are tracked at the BUILD.gn level (patched_dart2js_sdk depends on
+  //  patched_sdk).
+  await writeDepsFile(Platform.script,
+      Uri.base.resolveUri(new Uri.file("$outDir.d")), platformFinalLocation,
+      packages: packages,
+      // To track dependencies of this script, we need to use a platform.dill
+      // file generated for the VM. The dependency on the patched_sdk at the
+      // BUILD level guarantees that this file already exists.
+      platform: Uri.base.resolveUri(
+          new Uri.directory(outDir).resolve('../patched_sdk/platform.dill')),
+      extraDependencies: deps,
+      verbose: false,
+      targetDart2js: false);
+
+  await new File.fromUri(platform).rename(platformFinalLocation.toFilePath());
+}
+
+_applyPatch(
+    SdkLibrary library, String sdkLibIn, String patchIn, String sdkOut) {
+  var libraryOut = path.join(sdkLibIn, library.path);
+  var libraryIn = libraryOut;
+
+  var libraryFile = getInputFile(libraryIn, canBeMissing: true);
+  if (libraryFile != null) {
+    var outPaths = <String>[libraryOut];
+    var libraryContents = libraryFile.readAsStringSync();
+
+    int inputModifyTime = libraryFile.lastModifiedSync().millisecondsSinceEpoch;
+    var partFiles = <File>[];
+    for (var part in parseDirectives(libraryContents).directives) {
+      if (part is PartDirective) {
+        var partPath = part.uri.stringValue;
+        outPaths.add(path.join(path.dirname(libraryOut), partPath));
+
+        var partFile =
+            getInputFile(path.join(path.dirname(libraryIn), partPath));
+        partFiles.add(partFile);
+        inputModifyTime = math.max(inputModifyTime,
+            partFile.lastModifiedSync().millisecondsSinceEpoch);
+      }
+    }
+
+    // See if we can find a patch file.
+    var patchPath = path.join(
+        patchIn, path.basenameWithoutExtension(libraryIn) + '_patch.dart');
+
+    var patchFile = getInputFile(patchPath, canBeMissing: true);
+    if (patchFile != null) {
+      inputModifyTime = math.max(
+          inputModifyTime, patchFile.lastModifiedSync().millisecondsSinceEpoch);
+    }
+
+    // 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() ||
+          outFile.lastModifiedSync().millisecondsSinceEpoch < inputModifyTime) {
+        needsUpdate = true;
+        break;
+      }
+    }
+
+    if (needsUpdate) {
+      var contents = <String>[libraryContents];
+      contents.addAll(partFiles.map((f) => f.readAsStringSync()));
+      if (patchFile != null) {
+        var patchContents = patchFile.readAsStringSync();
+        contents = _patchLibrary(patchFile.path, contents, patchContents);
+      }
+
+      for (var i = 0; i < outPaths.length; i++) {
+        _writeSync(outPaths[i], contents[i]);
+      }
+    }
+  }
+}
+
 /// Writes a file, creating the directory if needed.
 void _writeSync(String filePath, String contents) {
   var outDir = new Directory(path.dirname(filePath));
   if (!outDir.existsSync()) outDir.createSync(recursive: true);
 
   new File(filePath).writeAsStringSync(contents);
 }
 
 /// Merges dart:* library code with code from *_patch.dart file.
 ///
@@ skipping 325 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;
 }