Copy resources.json for linking (#1177)

The `resources.json` should be copied to the link outputs, so that it can be inspected, cached, and used as a dependency to determine if a link hook needs to rerun.

This adds it as a regular dependency for now - we probably rather want to have some custom logic later, which doesn't rerun the link hook if only things like line numbers change.

---

<details>
  <summary>Contribution guidelines:</summary><br>

- See our [contributor guide](https://github.com/dart-lang/.github/blob/main/CONTRIBUTING.md) for general expectations for PRs.
- Larger or significant changes should be discussed in an issue before creating a PR.
- Contributions to our repos should follow the [Dart style guide](https://dart.dev/guides/language/effective-dart) and use `dart format`.
- Most changes should add an entry to the changelog and may need to [rev the pubspec package version](https://github.com/dart-lang/sdk/wiki/External-Package-Maintenance#making-a-change).
- Changes to packages require [corresponding tests](https://github.com/dart-lang/.github/blob/main/CONTRIBUTING.md#Testing).

Note that many Dart repos have a weekly cadence for reviewing PRs - please allow for some latency before initial review feedback.
</details>

pkgs/native_assets_builder/CHANGELOG.md

@@ -9,6 +9,7 @@
   Link hooks are not ordered.
 - Fix test.
 - Bump `package:native_assets_cli` to 0.6.0.
+- Copy `resources.json` to the build directory.
 
 ## 0.6.0
 

pkgs/native_assets_builder/lib/src/build_runner/build_runner.dart

@@ -211,15 +211,23 @@ class NativeAssetsBuildRunner {
       supportedAssetTypes: supportedAssetTypes,
       hook: hook,
     );
-    final outDirUri =
-        packageLayout.dartToolNativeAssetsBuilder.resolve('$buildDirName/out/');
+    final buildDirUri =
+        packageLayout.dartToolNativeAssetsBuilder.resolve('$buildDirName/');
+    final outDirUri = buildDirUri.resolve('out/');
     final outDir = Directory.fromUri(outDirUri);
     if (!await outDir.exists()) {
       // TODO(https://dartbug.com/50565): Purge old or unused folders.
       await outDir.create(recursive: true);
     }
 
     if (hook == Hook.link) {
+      File? resourcesFile;
+      if (resourceIdentifiers != null) {
+        resourcesFile = File.fromUri(buildDirUri.resolve('resources.json'));
+        await resourcesFile.create();
+        await File.fromUri(resourceIdentifiers).copy(resourcesFile.path);
+      }
+
       return LinkConfigImpl(
         outputDirectory: outDirUri,
         packageName: package.name,
@@ -230,7 +238,7 @@ class NativeAssetsBuildRunner {
         targetIOSSdk: targetIOSSdk,
         cCompiler: cCompilerConfig,
         targetAndroidNdkApi: targetAndroidNdkApi,
-        resourceIdentifierUri: resourceIdentifiers,
+        resourceIdentifierUri: resourcesFile?.uri,
         assets: buildResult!.assetsForLinking[package.name] ?? [],
         supportedAssetTypes: supportedAssetTypes,
         linkModePreference: linkModePreference,
@@ -388,9 +396,6 @@ class NativeAssetsBuildRunner {
     Uri? resources,
   ) async {
     final outDir = config.outputDirectory;
-    if (!await Directory.fromUri(outDir).exists()) {
-      await Directory.fromUri(outDir).create(recursive: true);
-    }
 
     final hookOutput = HookOutputImpl.readFromFile(file: config.outputFile);
     if (hookOutput != null) {

pkgs/native_assets_builder/test/build_runner/helpers.dart

@@ -73,6 +73,7 @@ Future<LinkResult> link(
   List<String>? capturedLogs,
   PackageLayout? packageLayout,
   required BuildResult buildResult,
+  Uri? resourceIdentifiers,
 }) async =>
     await runWithLog(capturedLogs, () async {
       final result = await NativeAssetsBuildRunner(
@@ -87,6 +88,7 @@ Future<LinkResult> link(
         includeParentEnvironment: includeParentEnvironment,
         packageLayout: packageLayout,
         buildResult: buildResult,
+        resourceIdentifiers: resourceIdentifiers,
       );
 
       if (result.success) {

pkgs/native_assets_builder/test/build_runner/resources_test.dart

@@ -0,0 +1,56 @@
+// 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';
+
+import 'package:test/test.dart';
+
+import '../helpers.dart';
+import 'helpers.dart';
+
+const Timeout longTimeout = Timeout(Duration(minutes: 5));
+
+void main() async {
+  test(
+    'simple_link linking',
+    timeout: longTimeout,
+    () async {
+      await inTempDir((tempUri) async {
+        await copyTestProjects(targetUri: tempUri);
+        final packageUri = tempUri.resolve('simple_link/');
+
+        final resourcesUri = tempUri.resolve('treeshaking_info.json');
+        await File.fromUri(resourcesUri).create();
+
+        // First, run `pub get`, we need pub to resolve our dependencies.
+        await runPubGet(
+          workingDirectory: packageUri,
+          logger: logger,
+        );
+
+        final buildResult = await build(
+          packageUri,
+          logger,
+          dartExecutable,
+        );
+
+        Iterable<String> buildFiles() => Directory.fromUri(
+                packageUri.resolve('.dart_tool/native_assets_builder/'))
+            .listSync(recursive: true)
+            .map((file) => file.path);
+
+        expect(buildFiles(), isNot(anyElement(endsWith('resources.json'))));
+
+        await link(
+          packageUri,
+          logger,
+          dartExecutable,
+          buildResult: buildResult,
+          resourceIdentifiers: resourcesUri,
+        );
+        expect(buildFiles(), anyElement(endsWith('resources.json')));
+      });
+    },
+  );
+}

pkgs/native_assets_cli/CHANGELOG.md

@@ -1,6 +1,7 @@
 ## 0.6.1-wip
 
 - Introduce `Builder` and `Linker` interface.
+- Copy `resources.json` to the build directory.
 
 ## 0.6.0
 

pkgs/native_assets_cli/lib/src/model/link_config.dart

@@ -18,11 +18,11 @@ class LinkConfigImpl extends HookConfigImpl implements LinkConfig {
 
   // TODO: Placeholder for the resources.json file URL. We don't want to change
   // native_assets_builder when implementing the parsing.
-  final Uri? _resourceIdentifierUri;
+  final Uri? resourceIdentifierUri;
 
   LinkConfigImpl({
     required this.assets,
-    Uri? resourceIdentifierUri,
+    this.resourceIdentifierUri,
     required super.outputDirectory,
     required super.packageName,
     required super.packageRoot,
@@ -36,25 +36,23 @@ class LinkConfigImpl extends HookConfigImpl implements LinkConfig {
     required super.targetOS,
     required super.linkModePreference,
     super.dryRun,
-  })  : _resourceIdentifierUri = resourceIdentifierUri,
-        super(
+  }) : super(
           hook: Hook.link,
           version: version ?? HookConfigImpl.latestVersion,
           supportedAssetTypes: supportedAssetTypes ?? [NativeCodeAsset.type],
         );
 
   LinkConfigImpl.dryRun({
     required this.assets,
-    Uri? resourceIdentifierUri,
+    this.resourceIdentifierUri,
     required super.outputDirectory,
     required super.packageName,
     required super.packageRoot,
     Version? version,
     Iterable<String>? supportedAssetTypes,
     required super.linkModePreference,
     required super.targetOS,
-  })  : _resourceIdentifierUri = resourceIdentifierUri,
-        super.dryRun(
+  }) : super.dryRun(
           hook: Hook.link,
           version: version ?? HookConfigImpl.latestVersion,
           supportedAssetTypes: supportedAssetTypes ?? [NativeCodeAsset.type],
@@ -72,8 +70,8 @@ class LinkConfigImpl extends HookConfigImpl implements LinkConfig {
   @override
   Map<String, Object> toJson() => {
         ...hookToJson(),
-        if (_resourceIdentifierUri != null)
-          resourceIdentifierKey: _resourceIdentifierUri.toFilePath(),
+        if (resourceIdentifierUri != null)
+          resourceIdentifierKey: resourceIdentifierUri!.toFilePath(),
         assetsKey: AssetImpl.listToJson(assets, version),
       }.sortOnKey();
 
@@ -129,7 +127,7 @@ class LinkConfigImpl extends HookConfigImpl implements LinkConfig {
     if (other is! LinkConfigImpl) {
       return false;
     }
-    if (other._resourceIdentifierUri != _resourceIdentifierUri) {
+    if (other.resourceIdentifierUri != resourceIdentifierUri) {
       return false;
     }
     if (!const DeepCollectionEquality().equals(other.assets, assets)) {
@@ -141,7 +139,7 @@ class LinkConfigImpl extends HookConfigImpl implements LinkConfig {
   @override
   int get hashCode => Object.hashAll([
         super.hashCode,
-        _resourceIdentifierUri,
+        resourceIdentifierUri,
         const DeepCollectionEquality().hash(assets),
       ]);