feat: teach cutler that Dart exists (#579)

packages/cutler/lib/commands/rebase_command.dart

@@ -106,8 +106,10 @@ class RebaseCommand extends CutlerCommand {
     }
 
     // Rebase our repos.
+    // These are done in a very specific order.
     var newHead = VersionSet(
       buildroot: doRebase(Repo.buildroot),
+      dart: doRebase(Repo.dart),
       engine: doRebase(Repo.engine),
       flutter: doRebase(Repo.flutter),
     );

packages/cutler/lib/model.dart

@@ -26,6 +26,14 @@ enum Repo {
     upstreamBranch: 'upstream/master',
   ),
 
+  /// Repo configuration representing the dart-lang/sdk repo.
+  dart(
+    name: 'dart',
+    path: 'engine/src/third_party/dart',
+    url: 'https://github.com/shorebirdtech/dart-sdk.git',
+    upstreamBranch: 'upstream/master',
+  ),
+
   /// Repo configuration representing the buildroot repo.
   buildroot(
     name: 'buildroot',
@@ -120,6 +128,7 @@ class VersionSet {
     required this.engine,
     required this.flutter,
     required this.buildroot,
+    required this.dart,
   });
 
   /// The engine version.
@@ -128,6 +137,9 @@ class VersionSet {
   /// The flutter version.
   final Version flutter;
 
+  /// The dart version.
+  final Version dart;
+
   /// The buildroot version.
   final Version buildroot;
 
@@ -136,14 +148,21 @@ class VersionSet {
         Repo.engine: engine,
         Repo.flutter: flutter,
         Repo.buildroot: buildroot,
+        Repo.dart: dart,
       }[repo]!;
 
   /// Copies the VersionSet replacing any provided values.
-  VersionSet copyWith({Version? engine, Version? flutter, Version? buildroot}) {
+  VersionSet copyWith({
+    Version? engine,
+    Version? flutter,
+    Version? buildroot,
+    Version? dart,
+  }) {
     return VersionSet(
       engine: engine ?? this.engine,
       flutter: flutter ?? this.flutter,
       buildroot: buildroot ?? this.buildroot,
+      dart: dart ?? this.dart,
     );
   }
 }

packages/cutler/lib/versions.dart

@@ -3,9 +3,15 @@ import 'package:cutler/model.dart';
 
 /// Print VersionSet [versions] to stdout at a given [indent] level.
 void printVersions(VersionSet versions, {int indent = 0}) {
-  print("${' ' * indent}flutter   ${versions.flutter}");
-  print("${' ' * indent}engine    ${versions.engine}");
-  print("${' ' * indent}buildroot ${versions.buildroot}");
+  final repos = [
+    Repo.flutter,
+    Repo.engine,
+    Repo.dart,
+    Repo.buildroot,
+  ];
+  for (final repo in repos) {
+    print("${' ' * indent}${repo.name.padRight(9)} ${versions[repo]}");
+  }
 }
 
 /// Returns a [VersionSet] for Flutter for a given [flutterHash].
@@ -18,16 +24,18 @@ VersionSet getFlutterVersions(String flutterHash) {
       .trim();
   final depsContents =
       Repo.engine.contentsAtPath(engineHash, Paths.engineDEPS.path);
-  final buildrootVersion = parseBuildRoot(depsContents);
+  final buildrootHash = parseBuildrootRevision(depsContents);
+  final dartHash = parseDartRevision(depsContents);
   return VersionSet(
     engine: Repo.engine.versionFrom(engineHash),
     flutter: Repo.flutter.versionFrom(flutterHash),
-    buildroot: Repo.buildroot.versionFrom(buildrootVersion),
+    buildroot: Repo.buildroot.versionFrom(buildrootHash),
+    dart: Repo.dart.versionFrom(dartHash),
   );
 }
 
-/// Parses the given DEPS file contents and returns the buildroot version.
-String parseBuildRoot(String depsContents) {
+/// Parses the given DEPS file contents and returns the buildroot revision.
+String parseBuildrootRevision(String depsContents) {
   final lines = depsContents.split('\n');
   // Example:
   //   'src': 'https://github.com/flutter/buildroot.git' + '@' + '059d155b4d452efd9c4427c45cddfd9445144869',
@@ -35,7 +43,22 @@ String parseBuildRoot(String depsContents) {
   final regexp = RegExp('([0-9a-f]{40})');
   final match = regexp.firstMatch(buildrootLine);
   if (match == null) {
-    throw Exception('Failed to parse buildroot version from $buildrootLine');
+    throw Exception('Failed to parse buildroot revision from $buildrootLine');
+  }
+  return match.group(0)!;
+}
+
+/// Parses the given DEPS file contents and returns the dart-lang/sdk revision.
+String parseDartRevision(String depsContents) {
+  final lines = depsContents.split('\n');
+  // Example:
+  //  'dart_revision': 'ce926bc6dcf649bd31a396e4e3961196115727cd',
+  final dartLine =
+      lines.firstWhere((line) => line.contains("'dart_revision': "));
+  final regexp = RegExp('([0-9a-f]{40})');
+  final match = regexp.firstMatch(dartLine);
+  if (match == null) {
+    throw Exception('Failed to parse dart revision from $dartLine');
   }
   return match.group(0)!;
 }

packages/cutler/test/cutler_test.dart

@@ -5,10 +5,15 @@ import 'package:cutler/versions.dart';
 import 'package:test/test.dart';
 
 void main() {
-  test('parseBuildRoot', () {
+  test('parseBuildrootVersion', () {
     final depsContents = File('test/fixtures/DEPS').readAsStringSync();
-    final buildrootVersion = parseBuildRoot(depsContents);
-    expect(buildrootVersion, 'd6c410f19de5947de40ce110c1e768c887870072');
+    final buildrootHash = parseBuildrootRevision(depsContents);
+    expect(buildrootHash, 'd6c410f19de5947de40ce110c1e768c887870072');
+  });
+  test('parseDartVersion', () {
+    final depsContents = File('test/fixtures/DEPS').readAsStringSync();
+    final dartHash = parseDartRevision(depsContents);
+    expect(dartHash, '7a6514d1377175decd3a886fe4190fbbebddac3a');
   });
   test('expandUser', () {
     final path = expandUser('~/foo/bar', env: {'HOME': '/home/user'});