Use dart run messages again

.github/workflows/messages.yml

@@ -49,6 +49,6 @@ jobs:
       - name: Regenerate and run example
         working-directory: pkgs/messages/example
         run: |
-          dart run messages_builder
+          dart run messages
           git diff --exit-code
           dart run

pkgs/messages/README.md

@@ -34,10 +34,9 @@ The `builder` to generate the named methods and data files from the input `arb`
 The logic for serializing `arb` message files into data files.
 
 ## Example
-Add `package:messages` and `package:messages_builder` to your dependencies:
+Add `package:messages` to your dependencies:
 ```bash
 dart pub add messages
-dart pub add dev:messages_builder
 ```
 
 Given translation message files in two languages:
@@ -68,7 +67,7 @@ This translated file was created by a translator given the reference `en.arb`.
 ```
 you can then run
 
-`dart run messages_builder`
+`dart run messages`
 
 This will generate both code to call your messages, as well as data files which will be shipped with your application. You can then use these generated files by importing the generated files:
 

pkgs/messages/bin/messages.dart

@@ -0,0 +1,31 @@
+// 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:io';
+
+Future<void> main(List<String> args) async {
+  final runBuilder = await Process.run('dart', ['run', 'messages_builder']);
+  stdout.write(runBuilder.stdout as String);
+
+  final runBuilderStdErr = runBuilder.stderr as String;
+  final messagesBuilderNotInDeps =
+      runBuilderStdErr.contains('Could not find package `messages_builder`');
+  if (messagesBuilderNotInDeps) {
+    print('Adding `package:messages_builder` to dev dependencies...');
+    final addBuilder = await runDart(['pub', 'add', 'dev:messages_builder']);
+    if (addBuilder.exitCode == 0) {
+      print('Re-running message generation');
+      await runDart(['run', 'messages_builder']);
+    }
+  } else {
+    stderr.write(runBuilderStdErr);
+  }
+}
+
+Future<ProcessResult> runDart(List<String> arguments) async {
+  final processResult = await Process.run('dart', arguments);
+  stdout.write(processResult.stdout as String);
+  stderr.write(processResult.stderr as String);
+  return processResult;
+}

pkgs/messages/examples_flutter/my_application/lib/src/empty_de.dart

@@ -0,0 +1 @@
+

pkgs/messages/examples_flutter/my_application/lib/src/empty_en.dart

@@ -0,0 +1 @@
+