[CFE] Add a few helper utils

These ease my life slightly.
Examples:

Compile to executable to get faster runs:
```
out/ReleaseX64/dart-sdk/bin/dart compile exe pkg/front_end/tool/gitformat_cl.dart -o ~/bin/format_cl
out/ReleaseX64/dart-sdk/bin/dart compile exe pkg/front_end/tool/git_branch_helper.dart -o ~/bin/gitbranch
```

Now I can format my entire CL with
```
$ format_cl
Using file:///path/to/dart-sdk/sdk/out/ReleaseX64/dart
stdout> Formatted 3 files (0 changed) in 0.35 seconds.
```

and get info about my branching with
```
$ gitbranch
├── origin/main
│   ├── add_a_few_cfe_util_tools [ahead 2]
```

Change-Id: I2e89196ab702660a1486894d22678e3cd0c07994
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/352641
Reviewed-by: Chloe Stefantsova <cstefantsova@google.com>
Commit-Queue: Jens Johansen <jensj@google.com>

pkg/front_end/presubmit_helper.dart

@@ -15,7 +15,7 @@ Future<void> main(List<String> args) async {
   // Expect something like /full/path/to/sdk/pkg/some_dir/whatever/else
   if (args.length != 1) throw "Need exactly one argument.";
 
-  final List<String> changedFiles = _getChangedFiles();
+  final List<String> changedFiles = getChangedFiles();
   String callerPath = args[0].replaceAll("\\", "/");
   if (!_shouldRun(changedFiles, callerPath)) {
     return;
@@ -290,7 +290,7 @@ Future<void> _executePendingWorkItems(List<Work> workItems) async {
 /// Queries git about changes against upstream, or origin/main if no upstream is
 /// set. This is similar (but different), I believe, to what
 /// `git cl presubmit` does.
-List<String> _getChangedFiles() {
+List<String> getChangedFiles() {
   ProcessResult result = Process.runSync(
       "git",
       [

pkg/front_end/test/spell_checking_list_tests.txt

@@ -414,6 +414,7 @@ inconsistencies
 increasing
 incrementally
 increments
+indention
 indents
 ing
 inhibit
@@ -516,6 +517,7 @@ mxn
 mysdk
 naively
 naturally
+needle
 negatable
 newworld
 ninja
@@ -634,6 +636,7 @@ rediscover
 reducer
 reenable
 referential
+refname
 refusing
 regards
 regenerate

pkg/front_end/tool/format_cl.dart

@@ -0,0 +1,106 @@
+// Copyright (c) 2024, 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 LineSplitter, utf8;
+import 'dart:developer' as dev show NativeRuntime;
+import 'dart:io';
+
+import '../presubmit_helper.dart' show getChangedFiles;
+import '../test/utils/io_utils.dart';
+
+Future<void> main() async {
+  Uri executable = getDartExecutable();
+  final List<String> allChangedFiles = getChangedFiles();
+  if (allChangedFiles.isEmpty) {
+    print("No changes in CL.");
+    return;
+  }
+  final List<String> changedDartFiles = [];
+  for (String changedFile in allChangedFiles) {
+    if (changedFile.toLowerCase().endsWith(".dart")) {
+      changedDartFiles.add(changedFile);
+    }
+  }
+  if (changedDartFiles.isEmpty) {
+    print("No changed dart files in CL.");
+    return;
+  }
+  Process p = await Process.start(
+      executable.toFilePath(), ["format", ...changedDartFiles]);
+
+  p.stderr
+      .transform(utf8.decoder)
+      .transform(const LineSplitter())
+      .listen((String line) {
+    stderr.writeln("stderr> $line");
+  });
+  p.stdout
+      .transform(utf8.decoder)
+      .transform(const LineSplitter())
+      .listen((String line) {
+    stdout.writeln("stdout> $line");
+  });
+
+  exitCode = await p.exitCode;
+}
+
+Uri getDartExecutable() {
+  Uri executable = Uri.base.resolve(Platform.resolvedExecutable);
+  if (executable == Platform.script || dev.NativeRuntime.buildId != null) {
+    // Probably aot compiled. We need to find "dart" another way.
+    bool found = false;
+    try {
+      final Uri repoDir = computeRepoDirUri();
+      for (String candidatePath in [
+        "out/ReleaseX64/dart",
+        "out/ReleaseX64/dart-sdk/bin/dart",
+        "out/ReleaseX64/dart.exe",
+        "out/ReleaseX64/dart-sdk/bin/dart.exe",
+        "xcodebuild/ReleaseX64/dart",
+        "xcodebuild/ReleaseX64/dart-sdk/bin/dart",
+      ]) {
+        Uri candidate = repoDir.resolve(candidatePath);
+        if (File.fromUri(candidate).existsSync()) {
+          executable = candidate;
+          found = true;
+          break;
+        }
+      }
+    } catch (e) {
+      print("Warning: $e");
+    }
+    if (!found) {
+      Uri? candidate = where("dart");
+      if (candidate != null) {
+        executable = candidate;
+      } else {
+        throw "Couldn't find a dart executable to use.";
+      }
+    }
+    print("Using $executable");
+  }
+  return executable;
+}
+
+Uri? where(String needle) {
+  String pathEnvironment = Platform.environment["PATH"] ?? '';
+  List<String> paths;
+  if (Platform.isWindows) {
+    paths = pathEnvironment.split(";");
+  } else {
+    paths = pathEnvironment.split(":");
+  }
+  // This isn't great but will probably work for our purposes.
+  List<String> extensions = ["", ".exe", ".bat", ".com"];
+
+  for (String path in paths) {
+    for (String extension in extensions) {
+      File f = new File("$path${Platform.pathSeparator}$needle$extension");
+      if (f.existsSync()) {
+        return f.uri;
+      }
+    }
+  }
+  return null;
+}

pkg/front_end/tool/git_branch_helper.dart

@@ -0,0 +1,144 @@
+// Copyright (c) 2024, 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:async';
+import 'dart:io';
+
+void main(List<String> args) {
+  // Use `runZonedGuarded` instead of try/catch, and do it here before anything
+  // else has been printed --- both because of
+  // https://github.com/dart-lang/sdk/issues/54911.
+  runZonedGuarded(() {
+    mainImpl(args);
+  }, (e, _) {
+    stderr.writeln("Error: $e");
+  });
+}
+
+const String CSI = "\x1b[";
+
+Map<String, GitBranch> branches = {};
+
+GitBranch getBranch(String name) {
+  GitBranch? result = branches[name];
+  if (result == null) {
+    result = branches[name] = new GitBranch(name);
+  }
+  return result;
+}
+
+void mainImpl(List<String> args) {
+  ProcessResult result = Process.runSync("git",
+      ["branch", "--list", "--format=%(refname:short)%09%(upstream:short)"],
+      runInShell: true);
+  result.stdout.split("\n").forEach(processGitBranchLine);
+
+  result =
+      Process.runSync("git", ["branch", "--show-current"], runInShell: true);
+  String currentBranchName = result.stdout;
+  currentBranchName = currentBranchName.trim();
+  GitBranch currentBranch = branches[currentBranchName]!;
+  Set<String> involvedBranchNames = {};
+  currentBranch.collectSelfAndParentNames(involvedBranchNames);
+  currentBranch.collectSelfAndChildrenNames(involvedBranchNames);
+
+  result = Process.runSync(
+      "git",
+      [
+        "branch",
+        "--list",
+        "--format=%(refname:short)%09%(upstream:track)",
+        ...involvedBranchNames
+      ],
+      runInShell: true);
+  result.stdout.split("\n").forEach(processGitBranchTrackLine);
+
+  int indentation = currentBranch.parent?.printSelfAndParentChain() ?? 0;
+
+  currentBranch.printSelfAndChildren(indentation, color: true);
+}
+
+void processGitBranchLine(String gitLine) {
+  if (gitLine.isEmpty) return;
+  int pos = gitLine.indexOf("\t");
+  String thisName = gitLine.substring(0, pos);
+  String parentName = gitLine.substring(pos + 1).trim();
+  GitBranch thisBranch = getBranch(thisName);
+  GitBranch parentBranch = getBranch(parentName);
+  parentBranch.registerChild(thisBranch);
+}
+
+void processGitBranchTrackLine(String gitLine) {
+  if (gitLine.isEmpty) return;
+  int pos = gitLine.indexOf("\t");
+  String thisName = gitLine.substring(0, pos);
+  String tracking = gitLine.substring(pos + 1).trim();
+  GitBranch thisBranch = getBranch(thisName);
+  thisBranch.tracking = tracking;
+}
+
+class GitBranch {
+  final String name;
+  GitBranch? parent;
+  final List<GitBranch> children = [];
+  String? tracking;
+
+  GitBranch(this.name);
+
+  void collectSelfAndChildrenNames(Set<String> names) {
+    names.add(name);
+    for (GitBranch child in children) {
+      child.collectSelfAndChildrenNames(names);
+    }
+  }
+
+  void collectSelfAndParentNames(Set<String> names) {
+    parent?.collectSelfAndParentNames(names);
+    names.add(name);
+  }
+
+  void printSelfAndChildren(int indention, {bool color = false}) {
+    _printLineWithIndention(indention, color: color);
+    for (GitBranch child in children) {
+      child.printSelfAndChildren(indention + 1);
+    }
+  }
+
+  int printSelfAndParentChain() {
+    int indention = 0;
+    GitBranch? parent = this.parent;
+    if (parent != null) {
+      indention = parent.printSelfAndParentChain();
+    }
+    _printLineWithIndention(indention);
+
+    return indention + 1;
+  }
+
+  void registerChild(GitBranch child) {
+    children.add(child);
+    child.parent = this;
+  }
+
+  @override
+  String toString() {
+    return "GitBranch[$name, children = $children]";
+  }
+
+  void _printLineWithIndention(int indention, {bool color = false}) {
+    stdout.write("│   " * (indention));
+    stdout.write("├── ");
+    if (color) {
+      stdout.write("${CSI}31m");
+    }
+    stdout.write("$name");
+    if (color) {
+      stdout.write("${CSI}0m");
+    }
+    if (tracking != null) {
+      stdout.write(" $tracking");
+    }
+    stdout.write("\n");
+  }
+}