[flutter_tools] rename output LICENSE file to NOTICES and support loading either (#57871)

Work towards #16723

This is only safe to land after #58131 lands in google3. Only build NOTICES in asset manfiest, and load either LICENSE or NOTICES from pubspec dependencies.

dev/devicelab/lib/framework/apk_utils.dart

@@ -11,7 +11,7 @@ import 'package:flutter_devicelab/framework/utils.dart';
 
 final List<String> flutterAssets = <String>[
   'assets/flutter_assets/AssetManifest.json',
-  'assets/flutter_assets/LICENSE',
+  'assets/flutter_assets/NOTICES',
   'assets/flutter_assets/fonts/MaterialIcons-Regular.ttf',
   'assets/flutter_assets/packages/cupertino_icons/assets/CupertinoIcons.ttf',
 ];

dev/devicelab/lib/tasks/perf_tests.dart

@@ -544,7 +544,7 @@ class CompileTest {
 
     final _UnzipListEntry libflutter = fileToMetadata['lib/armeabi-v7a/libflutter.so'];
     final _UnzipListEntry libapp = fileToMetadata['lib/armeabi-v7a/libapp.so'];
-    final _UnzipListEntry license = fileToMetadata['assets/flutter_assets/LICENSE'];
+    final _UnzipListEntry license = fileToMetadata['assets/flutter_assets/NOTICES'];
 
     return <String, dynamic>{
       'libflutter_uncompressed_bytes': libflutter.uncompressedSize,

packages/flutter_tools/lib/src/asset.dart

@@ -82,9 +82,9 @@ class ManifestAssetBundle implements AssetBundle {
 
   DateTime _lastBuildTimestamp;
 
-  static const String _assetManifestJson = 'AssetManifest.json';
-  static const String _fontSetMaterial = 'material';
-  static const String _license = 'LICENSE';
+  static const String _kAssetManifestJson = 'AssetManifest.json';
+  static const String _kFontSetMaterial = 'material';
+  static const String _kNoticeFile = 'NOTICES';
 
   @override
   bool wasBuiltOnce() => _lastBuildTimestamp != null;
@@ -149,7 +149,7 @@ class ManifestAssetBundle implements AssetBundle {
     // device.
     _lastBuildTimestamp = DateTime.now();
     if (flutterManifest.isEmpty) {
-      entries[_assetManifestJson] = DevFSStringContent('{}');
+      entries[_kAssetManifestJson] = DevFSStringContent('{}');
       return 0;
     }
 
@@ -254,7 +254,7 @@ class ManifestAssetBundle implements AssetBundle {
 
     final List<_Asset> materialAssets = <_Asset>[
       if (flutterManifest.usesMaterialDesign && includeDefaultFonts)
-        ..._getMaterialAssets(_fontSetMaterial),
+        ..._getMaterialAssets(_kFontSetMaterial),
     ];
     for (final _Asset asset in materialAssets) {
       assert(asset.assetFileExists);
@@ -285,9 +285,9 @@ class ManifestAssetBundle implements AssetBundle {
         globals.fs.file('DOES_NOT_EXIST_RERUN_FOR_WILDCARD$suffix').absolute);
     }
 
-    _setIfChanged(_assetManifestJson, assetManifest);
+    _setIfChanged(_kAssetManifestJson, assetManifest);
     _setIfChanged(kFontManifestJson, fontManifest);
-    _setIfChanged(_license, licenses);
+    _setIfChanged(_kNoticeFile, licenses);
     return 0;
   }
 
@@ -395,28 +395,23 @@ List<_Asset> _getMaterialAssets(String fontSet) {
 }
 
 
-/// Processes dependencies into a string representing the license file.
+/// Processes dependencies into a string representing the NOTICES file.
 ///
-/// Reads the LICENSE file from each package in the .packages file, splitting
-/// each one into each component license (so that we can de-dupe if possible).
-/// If provided with a pubspec.yaml file, only direct depedencies are included
-/// in the resulting LICENSE file.
+/// Reads the NOTICES or LICENSE file from each package in the .packages file,
+/// splitting each one into each component license so that it can be de-duped
+/// if possible. If the NOTICES file exists, it is preferred over the LICENSE
+/// file.
 ///
 /// Individual licenses inside each LICENSE file should be separated by 80
 /// hyphens on their own on a line.
 ///
-/// If a LICENSE file contains more than one component license, then each
-/// component license must start with the names of the packages to which the
-/// component license applies, with each package name on its own line, and the
-/// list of package names separated from the actual license text by a blank
-/// line. (The packages need not match the names of the pub package. For
+/// If a LICENSE or NOTICES file contains more than one component license,
+/// then each component license must start with the names of the packages to
+/// which the component license applies, with each package name on its own line
+/// and the list of package names separated from the actual license text by a
+/// blank line. The packages need not match the names of the pub package. For
 /// example, a package might itself contain code from multiple third-party
-/// sources, and might need to include a license for each one.)
-// Note: this logic currently has a bug, in that we collect LICENSE information
-// for dev_dependencies and transitive dev_dependencies. These are not actually
-// compiled into the released application and don't need to be included. Unfortunately,
-// the pubspec.yaml alone does not have enough information to determine which
-// dependencies are transitive of dev_dependencies, so a simple filter isn't sufficient.
+/// sources, and might need to include a license for each one.
 class LicenseCollector {
   LicenseCollector({
     @required FileSystem fileSystem
@@ -440,7 +435,11 @@ class LicenseCollector {
       if (packageUri == null || packageUri.scheme != 'file') {
         continue;
       }
-      final File file = _fileSystem.file(packageUri.resolve('../LICENSE'));
+      // First check for NOTICES, then fallback to LICENSE
+      File file = _fileSystem.file(packageUri.resolve('../NOTICES'));
+      if (!file.existsSync()) {
+        file = _fileSystem.file(packageUri.resolve('../LICENSE'));
+      }
       if (!file.existsSync()) {
         continue;
       }
@@ -527,7 +526,7 @@ List<Map<String, dynamic>> _parseFonts(
 }) {
   return <Map<String, dynamic>>[
     if (manifest.usesMaterialDesign && includeDefaultFonts)
-      ..._getMaterialFonts(ManifestAssetBundle._fontSetMaterial),
+      ..._getMaterialFonts(ManifestAssetBundle._kFontSetMaterial),
     if (packageName == null)
       ...manifest.fontsDescriptor
     else

packages/flutter_tools/test/general.shard/asset_bundle_test.dart

@@ -211,14 +211,14 @@ assets:
       as DevFSStringContent;
     final DevFSStringContent fontManifest = bundle.entries['FontManifest.json']
       as DevFSStringContent;
-    final DevFSStringContent license = bundle.entries['LICENSE']
+    final DevFSStringContent license = bundle.entries['NOTICES']
       as DevFSStringContent;
 
     await bundle.build(manifestPath: 'pubspec.yaml');
 
     expect(assetManifest, bundle.entries['AssetManifest.json']);
     expect(fontManifest, bundle.entries['FontManifest.json']);
-    expect(license, bundle.entries['LICENSE']);
+    expect(license, bundle.entries['NOTICES']);
   }, overrides: <Type, Generator>{
     FileSystem: () => MemoryFileSystem.test(),
     ProcessManager: () => FakeProcessManager.any(),

packages/flutter_tools/test/general.shard/build_system/targets/assets_test.dart

@@ -89,7 +89,7 @@ flutter:
 
     expect(fileSystem.file('${environment.buildDir.path}/flutter_assets/AssetManifest.json'), exists);
     expect(fileSystem.file('${environment.buildDir.path}/flutter_assets/FontManifest.json'), exists);
-    expect(fileSystem.file('${environment.buildDir.path}/flutter_assets/LICENSE'), exists);
+    expect(fileSystem.file('${environment.buildDir.path}/flutter_assets/NOTICES'), exists);
     // See https://github.com/flutter/flutter/issues/35293
     expect(fileSystem.file('${environment.buildDir.path}/flutter_assets/assets/foo/bar.png'), exists);
     // See https://github.com/flutter/flutter/issues/46163

packages/flutter_tools/test/general.shard/license_collector_test.dart

@@ -249,12 +249,16 @@ void main() {
   });
 
   testWithoutContext('processes dependent licenses according to instructions', () async {
-    fileSystem.file('foo/LICENSE')
+    fileSystem.file('foo/NOTICES')
       ..createSync(recursive: true)
       ..writeAsStringSync(_kMitLicense);
-    fileSystem.file('bar/LICENSE')
+    fileSystem.file('bar/NOTICES')
       ..createSync(recursive: true)
       ..writeAsStringSync(_kApacheLicense);
+    // NOTICES is preferred over LICENSE
+    fileSystem.file('bar/LICENSE')
+      ..createSync(recursive: true)
+      ..writeAsStringSync('SHOULD NOT BE INCLUDED');
     fileSystem.file('fizz/LICENSE')
       ..createSync(recursive: true)
       ..writeAsStringSync(_kMitLicense); // intentionally a duplicate
@@ -292,14 +296,17 @@ void main() {
     expect(result.combinedLicenses, contains(_kApacheLicense));
     expect(result.combinedLicenses, contains(_kMitLicense));
 
+    // String from LICENSE file was not included when NOTICES exists.
+    expect(result.combinedLicenses, isNot(contains('SHOULD NOT BE INCLUDED')));
+
     // Licenses are de-duplicated correctly.
     expect(result.combinedLicenses.split(LicenseCollector.licenseSeparator), hasLength(2));
 
     // All input licenses included in result.
     final Iterable<String> filePaths = result.dependencies.map((File file) => file.path);
     expect(filePaths, unorderedEquals(<String>[
-      '/foo/LICENSE',
-      '/bar/LICENSE',
+      '/foo/NOTICES',
+      '/bar/NOTICES',
       '/fizz/LICENSE'
     ]));
   });