Migrate pkg/dart2native to null safety

Change-Id: I87e4fd454b8e52acc17243495295ffee9dfd79bc
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/208986
Auto-Submit: Alexander Markov <alexmarkov@google.com>
Commit-Queue: Alexander Markov <alexmarkov@google.com>
Reviewed-by: Martin Kustermann <kustermann@google.com>

.dart_tool/package_config.json

@@ -11,7 +11,7 @@
     "constraint, update this by running tools/generate_package_config.dart."
   ],
   "configVersion": 2,
-  "generated": "2021-08-04T21:18:41.561058",
+  "generated": "2021-08-04T16:42:24.433381",
   "generator": "tools/generate_package_config.dart",
   "packages": [
     {
@@ -226,7 +226,7 @@
       "name": "dart2native",
       "rootUri": "../pkg/dart2native",
       "packageUri": "lib/",
-      "languageVersion": "2.7"
+      "languageVersion": "2.12"
     },
     {
       "name": "dart_internal",

pkg/dart2native/bin/dart2native.dart

@@ -21,7 +21,7 @@ Generates an executable or an AOT snapshot from <main-dart-file>.
 
 Future<void> main(List<String> args) async {
   // If we're outputting to a terminal, wrap usage text to that width.
-  int outputLineWidth;
+  int? outputLineWidth;
   try {
     outputLineWidth = stdout.terminalColumns;
   } catch (_) {/* Ignore. */}

pkg/dart2native/lib/dart2native.dart

@@ -44,7 +44,7 @@ Future<ProcessResult> generateAotKernel(
     String platformDill,
     String sourceFile,
     String kernelFile,
-    String packages,
+    String? packages,
     List<String> defines,
     {String enableExperiment = '',
     List<String> extraGenKernelOptions = const []}) {
@@ -68,7 +68,7 @@ Future generateAotSnapshot(
     String genSnapshot,
     String kernelFile,
     String snapshotFile,
-    String debugFile,
+    String? debugFile,
     bool enableAsserts,
     List<String> extraGenSnapshotOptions) {
   return Process.run(genSnapshot, [

pkg/dart2native/lib/generate.dart

@@ -21,14 +21,14 @@ final String productPlatformDill = path.join(
 
 Future<void> generateNative({
   String kind = 'exe',
-  String sourceFile,
-  String outputFile,
-  String debugFile,
-  String packages,
-  List<String> defines,
+  required String sourceFile,
+  String? outputFile,
+  String? debugFile,
+  String? packages,
+  required List<String> defines,
   String enableExperiment = '',
   bool enableAsserts = false,
-  bool soundNullSafety,
+  bool? soundNullSafety,
   bool verbose = false,
   String verbosity = 'all',
   List<String> extraOptions = const [],
@@ -42,13 +42,13 @@ Future<void> generateNative({
     final Kind outputKind = {
       'aot': Kind.aot,
       'exe': Kind.exe,
-    }[kind];
+    }[kind]!;
     final sourceWithoutDart = sourcePath.replaceFirst(RegExp(r'\.dart$'), '');
     final outputPath = path.canonicalize(path.normalize(outputFile ??
         {
           Kind.aot: '$sourceWithoutDart.aot',
           Kind.exe: '$sourceWithoutDart.exe',
-        }[outputKind]));
+        }[outputKind]!));
     final debugPath =
         debugFile != null ? path.canonicalize(path.normalize(debugFile)) : null;
 

pkg/dart2native/pubspec.yaml

@@ -3,7 +3,7 @@ name: dart2native
 publish_to: none
 
 environment:
-  sdk: "^2.7.0"
+  sdk: '>=2.12.0 <3.0.0'
 
 # Add the bin/dart2native.dart script to the scripts pub installs.
 executables: