From be97d03a25851f70a8dc4d00b30f3dd4e445614c Mon Sep 17 00:00:00 2001
From: Jackson Gardner <jacksongardner@google.com>
Date: Thu, 16 Mar 2023 16:13:04 -0700
Subject: [PATCH] Use depfile with dart2wasm to determine when to rebuild.
 (#122817)

Use depfile with dart2wasm to determine when to rebuild.
---
 .../flutter_tools/lib/src/build_system/targets/web.dart   | 8 ++++++++
 .../test/general.shard/build_system/targets/web_test.dart | 3 +++
 2 files changed, 11 insertions(+)

diff --git a/packages/flutter_tools/lib/src/build_system/targets/web.dart b/packages/flutter_tools/lib/src/build_system/targets/web.dart
index e69dbda3a46..1398ae8c591 100644
--- a/packages/flutter_tools/lib/src/build_system/targets/web.dart
+++ b/packages/flutter_tools/lib/src/build_system/targets/web.dart
@@ -295,6 +295,7 @@ class Dart2WasmTarget extends Dart2WebTarget {
     final BuildMode buildMode = getBuildModeForName(buildModeEnvironment);
     final Artifacts artifacts = globals.artifacts!;
     final File outputWasmFile = environment.buildDir.childFile('main.dart.wasm');
+    final File depFile = environment.buildDir.childFile('dart2wasm.d');
     final String dartSdkPath = artifacts.getArtifactPath(Artifact.engineDartSdkPath, platform: TargetPlatform.web_javascript);
     final String dartSdkRoot = environment.fileSystem.directory(dartSdkPath).parent.path;
 
@@ -319,10 +320,12 @@ class Dart2WasmTarget extends Dart2WebTarget {
       dartSdkRoot,
       '--libraries-spec',
       artifacts.getHostArtifact(HostArtifact.flutterWebLibrariesJson).path,
+      '--depfile=${depFile.path}',
 
       environment.buildDir.childFile('main.dart').path, // dartfile
       outputWasmFile.path,
     ];
+    globals.printTrace('compiling dart code to wasm with command "${compilationArgs.join(' ')}"');
     final ProcessResult compileResult = await globals.processManager.run(compilationArgs);
     if (compileResult.exitCode != 0) {
       throw Exception(_collectOutput(compileResult));
@@ -335,6 +338,11 @@ class Dart2WasmTarget extends Dart2WebTarget {
   @override
   String get name => 'dart2wasm';
 
+  @override
+  List<String> get depfiles => const <String>[
+    'dart2wasm.d',
+  ];
+
   @override
   List<Source> get outputs => const <Source>[
     Source.pattern('{OUTPUT_DIR}/main.dart.wasm'),
diff --git a/packages/flutter_tools/test/general.shard/build_system/targets/web_test.dart b/packages/flutter_tools/test/general.shard/build_system/targets/web_test.dart
index 16893898c43..47b37a13f84 100644
--- a/packages/flutter_tools/test/general.shard/build_system/targets/web_test.dart
+++ b/packages/flutter_tools/test/general.shard/build_system/targets/web_test.dart
@@ -778,6 +778,8 @@ void main() {
     environment.defines[kBuildMode] = 'profile';
     environment.defines[kDartDefines] = encodeDartDefines(<String>['FOO=bar', 'BAZ=qux']);
 
+    final File depFile = environment.buildDir.childFile('dart2wasm.d');
+
     processManager.addCommand(FakeCommand(
       command: <String>[
         'bin/cache/dart-sdk/bin/dartaotruntime',
@@ -796,6 +798,7 @@ void main() {
         'bin/cache',
         '--libraries-spec',
         'bin/cache/flutter_web_sdk/libraries.json',
+        '--depfile=${depFile.absolute.path}',
 
         environment.buildDir.childFile('main.dart').absolute.path,
         environment.buildDir.childFile('main.dart.wasm').absolute.path,