[pigeon] Enable NNBD in tool (#1532)

Opts Pigeon into running in NNBD mode. All of the code had already been converted.

Also updates a legacy Dart command (dart pub run) in the test script to the modern version.

Author: stuartmorgan-g

packages/pigeon/CHANGELOG.md

@@ -1,3 +1,8 @@
+## 3.0.1
+
+* Enables NNBD for the Pigeon tool itself.
+* [tests] Updates legacy Dart commands.
+
 ## 3.0.0
 
 * **BREAKING CHANGE**: Removes the `--dart_null_safety` flag. Generated Dart

packages/pigeon/bin/pigeon.dart

@@ -2,8 +2,6 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-// @dart = 2.2
-
 import 'dart:io' show exit;
 
 import 'package:pigeon/pigeon_cl.dart';

packages/pigeon/bin/run_tests.dart

@@ -209,7 +209,6 @@ Future<int> _runPigeon(
     bool streamOutput = true}) async {
   const bool hasDart = false;
   final List<String> args = <String>[
-    'pub',
     'run',
     'pigeon',
     '--input',

packages/pigeon/lib/generator_tools.dart

@@ -8,7 +8,7 @@ import 'dart:mirrors';
 import 'ast.dart';
 
 /// The current version of pigeon. This must match the version in pubspec.yaml.
-const String pigeonVersion = '3.0.0';
+const String pigeonVersion = '3.0.1';
 
 /// Read all the content from [stdin] to a String.
 String readStdin() {

packages/pigeon/pubspec.yaml

@@ -2,7 +2,7 @@ name: pigeon
 description: Code generator tool to make communication between Flutter and the host platform type-safe and easier.
 repository: https://github.com/flutter/packages/tree/main/packages/pigeon
 issue_tracker: https://github.com/flutter/flutter/issues?q=is%3Aissue+is%3Aopen+label%3Apigeon
-version: 3.0.0 # This must match the version in lib/generator_tools.dart
+version: 3.0.1 # This must match the version in lib/generator_tools.dart
 
 environment:
   sdk: ">=2.12.0 <3.0.0"