Use persisted build information to automatically clean old outputs in assemble (#39654)

packages/flutter_tools/lib/src/build_system/targets/linux.dart

@@ -29,7 +29,6 @@ class UnpackLinux extends Target {
     Source.pattern('{PROJECT_DIR}/linux/flutter/flutter_plugin_registrar.h'),
     Source.pattern('{PROJECT_DIR}/linux/flutter/flutter_glfw.h'),
     Source.pattern('{PROJECT_DIR}/linux/flutter/icudtl.dat'),
-    Source.pattern('{PROJECT_DIR}/linux/flutter/cpp_client_wrapper_glfw/*'),
   ];
 
   @override

packages/flutter_tools/lib/src/build_system/targets/macos.dart

@@ -122,9 +122,6 @@ abstract class UnpackMacOS extends Target {
     final Directory targetDirectory = environment
       .outputDir
       .childDirectory('FlutterMacOS.framework');
-    if (targetDirectory.existsSync()) {
-      targetDirectory.deleteSync(recursive: true);
-    }
 
     final ProcessResult result = await processManager
         .run(<String>['cp', '-R', basePath, targetDirectory.path]);
@@ -325,11 +322,6 @@ abstract class MacOSBundleFlutterAssets extends Target {
     final Directory assetDirectory = outputDirectory
       .childDirectory('Resources')
       .childDirectory('flutter_assets');
-    // We're not smart enough to only remove assets that are removed. If
-    // anything changes blow away the whole directory.
-    if (assetDirectory.existsSync()) {
-      assetDirectory.deleteSync(recursive: true);
-    }
     assetDirectory.createSync(recursive: true);
     final AssetBundle assetBundle = AssetBundleFactory.instance.createBundle();
     final int result = await assetBundle.build(

packages/flutter_tools/lib/src/build_system/targets/windows.dart

@@ -32,7 +32,6 @@ class UnpackWindows extends Target {
     Source.pattern('{PROJECT_DIR}/windows/flutter/flutter_plugin_registrar.h'),
     Source.pattern('{PROJECT_DIR}/windows/flutter/flutter_windows.h'),
     Source.pattern('{PROJECT_DIR}/windows/flutter/icudtl.dat'),
-    Source.pattern('{PROJECT_DIR}/windows/flutter/cpp_client_wrapper/*'),
   ];
 
   @override

packages/flutter_tools/test/general.shard/build_system/build_system_test.dart

@@ -126,7 +126,7 @@ void main() {
     final BuildResult result = await buildSystem.build(badTarget, environment);
 
     expect(result.hasException, true);
-    expect(result.exceptions.values.single.exception, isInstanceOf<MissingOutputException>());
+    expect(result.exceptions.values.single.exception, isInstanceOf<FileSystemException>());
   }));
 
   test('Saves a stamp file with inputs and outputs', () => testbed.run(() async {
@@ -211,6 +211,52 @@ void main() {
     expect(shared, 1);
   }));
 
+  test('Automatically cleans old outputs when dag changes', () => testbed.run(() async {
+    final TestTarget testTarget = TestTarget((Environment envionment) async {
+      environment.buildDir.childFile('foo.out').createSync();
+    })
+      ..inputs = const <Source>[Source.pattern('{PROJECT_DIR}/foo.dart')]
+      ..outputs = const <Source>[Source.pattern('{BUILD_DIR}/foo.out')];
+    fs.file('foo.dart').createSync();
+
+    await buildSystem.build(testTarget, environment);
+
+    expect(environment.buildDir.childFile('foo.out').existsSync(), true);
+
+    final TestTarget testTarget2 = TestTarget((Environment envionment) async {
+      environment.buildDir.childFile('bar.out').createSync();
+    })
+      ..inputs = const <Source>[Source.pattern('{PROJECT_DIR}/foo.dart')]
+      ..outputs = const <Source>[Source.pattern('{BUILD_DIR}/bar.out')];
+
+    await buildSystem.build(testTarget2, environment);
+
+    expect(environment.buildDir.childFile('bar.out').existsSync(), true);
+    expect(environment.buildDir.childFile('foo.out').existsSync(), false);
+  }));
+
+  test('reruns build if stamp is corrupted', () => testbed.run(() async {
+    final TestTarget testTarget = TestTarget((Environment envionment) async {
+      environment.buildDir.childFile('foo.out').createSync();
+    })
+      ..inputs = const <Source>[Source.pattern('{PROJECT_DIR}/foo.dart')]
+      ..outputs = const <Source>[Source.pattern('{BUILD_DIR}/foo.out')];
+    fs.file('foo.dart').createSync();
+    await buildSystem.build(testTarget, environment);
+
+    // invalid JSON
+    environment.buildDir.childFile('test.stamp').writeAsStringSync('{X');
+    await buildSystem.build(testTarget, environment);
+
+    // empty file
+    environment.buildDir.childFile('test.stamp').writeAsStringSync('');
+    await buildSystem.build(testTarget, environment);
+
+    // invalid format
+    environment.buildDir.childFile('test.stamp').writeAsStringSync('{"inputs": 2, "outputs": 3}');
+    await buildSystem.build(testTarget, environment);
+  }));
+
 
   test('handles a throwing build action', () => testbed.run(() async {
     final BuildResult result = await buildSystem.build(fizzTarget, environment);