[flutter_tools] switch dart defines to base64 to avoid windows control characters (#75027)

= gets escaped into %3D which seems to be tripping up cmake on windows since % is a control character. Switch to base64 encoding, since this does not have % nor , in the output character set.

This change is not trivially cherry pickable, and isn't tested on windows aside from my local, manual tests due to the planned CI work not being complete yet.

Fixes #75017
Fixes #74705

packages/flutter_tools/bin/tool_backend.dart

@@ -56,7 +56,6 @@ or
   ]);
   final String bundlePlatform = targetPlatform == 'windows-x64' ? 'windows' : 'linux';
   final String target = '${buildMode}_bundle_${bundlePlatform}_assets';
-
   final Process assembleProcess = await Process.start(
     flutterExecutable,
     <String>[

packages/flutter_tools/lib/src/android/gradle.dart

@@ -308,15 +308,8 @@ Future<void> buildGradleApp({
   if (target != null) {
     command.add('-Ptarget=$target');
   }
-  assert(buildInfo.trackWidgetCreation != null);
-  command.add('-Ptrack-widget-creation=${buildInfo.trackWidgetCreation}');
+  command.addAll(androidBuildInfo.buildInfo.toGradleConfig());
 
-  if (buildInfo.extraFrontEndOptions != null) {
-    command.add('-Pextra-front-end-options=${encodeDartDefines(buildInfo.extraFrontEndOptions)}');
-  }
-  if (buildInfo.extraGenSnapshotOptions != null) {
-    command.add('-Pextra-gen-snapshot-options=${encodeDartDefines(buildInfo.extraGenSnapshotOptions)}');
-  }
   if (buildInfo.fileSystemRoots != null && buildInfo.fileSystemRoots.isNotEmpty) {
     command.add('-Pfilesystem-roots=${buildInfo.fileSystemRoots.join('|')}');
   }
@@ -326,9 +319,6 @@ Future<void> buildGradleApp({
   if (androidBuildInfo.splitPerAbi) {
     command.add('-Psplit-per-abi=true');
   }
-  if (androidBuildInfo.buildInfo.dartDefines?.isNotEmpty ?? false) {
-    command.add('-Pdart-defines=${encodeDartDefines(androidBuildInfo.buildInfo.dartDefines)}');
-  }
   if (shouldBuildPluginAsAar) {
     // Pass a system flag instead of a project flag, so this flag can be
     // read from include_flutter.groovy.
@@ -339,24 +329,6 @@ Future<void> buildGradleApp({
   if (androidBuildInfo.fastStart) {
     command.add('-Pfast-start=true');
   }
-  if (androidBuildInfo.buildInfo.splitDebugInfoPath != null) {
-    command.add('-Psplit-debug-info=${androidBuildInfo.buildInfo.splitDebugInfoPath}');
-  }
-  if (androidBuildInfo.buildInfo.treeShakeIcons) {
-    command.add('-Ptree-shake-icons=true');
-  }
-  if (androidBuildInfo.buildInfo.dartObfuscation) {
-    command.add('-Pdart-obfuscation=true');
-  }
-  if (androidBuildInfo.buildInfo.bundleSkSLPath != null) {
-    command.add('-Pbundle-sksl-path=${androidBuildInfo.buildInfo.bundleSkSLPath}');
-  }
-  if (androidBuildInfo.buildInfo.performanceMeasurementFile != null) {
-    command.add('-Pperformance-measurement-file=${androidBuildInfo.buildInfo.performanceMeasurementFile}');
-  }
-  if (buildInfo.codeSizeDirectory != null) {
-    command.add('-Pcode-size-directory=${buildInfo.codeSizeDirectory}');
-  }
   command.add(assembleTask);
 
   GradleHandledError detectedGradleError;
@@ -611,18 +583,12 @@ Future<void> buildGradleAar({
   if (target != null && target.isNotEmpty) {
     command.add('-Ptarget=$target');
   }
-  if (buildInfo.splitDebugInfoPath != null) {
-    command.add('-Psplit-debug-info=${buildInfo.splitDebugInfoPath}');
-  }
-  if (buildInfo.treeShakeIcons) {
-    command.add('-Pfont-subset=true');
-  }
-  if (buildInfo.dartObfuscation) {
-    if (buildInfo.mode == BuildMode.debug || buildInfo.mode == BuildMode.profile) {
-      globals.printStatus('Dart obfuscation is not supported in ${toTitleCase(buildInfo.friendlyModeName)} mode, building as un-obfuscated.');
-    } else {
-      command.add('-Pdart-obfuscation=true');
-    }
+  command.addAll(androidBuildInfo.buildInfo.toGradleConfig());
+  if (buildInfo.dartObfuscation && buildInfo.mode !=  BuildMode.release) {
+    globals.printStatus(
+      'Dart obfuscation is not supported in ${toTitleCase(buildInfo.friendlyModeName)}'
+      ' mode, building as un-obfuscated.',
+    );
   }
 
   if (globals.artifacts is LocalEngineArtifacts) {

packages/flutter_tools/lib/src/build_info.dart

@@ -13,6 +13,7 @@ import 'base/file_system.dart';
 import 'base/logger.dart';
 import 'base/utils.dart';
 import 'build_system/targets/icon_tree_shaker.dart';
+import 'convert.dart';
 import 'globals.dart' as globals;
 
 /// Information about a build to be performed or used.
@@ -192,9 +193,9 @@ class BuildInfo {
       if (dartObfuscation != null)
         'DART_OBFUSCATION': dartObfuscation.toString(),
       if (extraFrontEndOptions?.isNotEmpty ?? false)
-        'EXTRA_FRONT_END_OPTIONS': encodeDartDefines(extraFrontEndOptions),
+        'EXTRA_FRONT_END_OPTIONS': extraFrontEndOptions?.join(','),
       if (extraGenSnapshotOptions?.isNotEmpty ?? false)
-        'EXTRA_GEN_SNAPSHOT_OPTIONS': encodeDartDefines(extraGenSnapshotOptions),
+        'EXTRA_GEN_SNAPSHOT_OPTIONS': extraGenSnapshotOptions?.join(','),
       if (splitDebugInfoPath != null)
         'SPLIT_DEBUG_INFO': splitDebugInfoPath,
       if (trackWidgetCreation != null)
@@ -211,6 +212,34 @@ class BuildInfo {
         'CODE_SIZE_DIRECTORY': codeSizeDirectory,
     };
   }
+
+  /// Convert this config to a series of project level arguments to be passed
+  /// on the command line to gradle.
+  List<String> toGradleConfig() {
+    // PACKAGE_CONFIG not currently supported.
+    return <String>[
+      if (dartDefines?.isNotEmpty ?? false)
+        '-Pdart-defines=${encodeDartDefines(dartDefines)}',
+      if (dartObfuscation != null)
+        '-Pdart-obfuscation=$dartObfuscation',
+      if (extraFrontEndOptions?.isNotEmpty ?? false)
+        '-Pextra-front-end-options=${extraFrontEndOptions?.join(',')}',
+      if (extraGenSnapshotOptions?.isNotEmpty ?? false)
+        '-Pextra-gen-snapshot-options=${extraGenSnapshotOptions?.join(',')}',
+      if (splitDebugInfoPath != null)
+        '-Psplit-debug-info=$splitDebugInfoPath',
+      if (trackWidgetCreation != null)
+        '-Ptrack-widget-creation=$trackWidgetCreation',
+      if (treeShakeIcons != null)
+        '-Ptree-shake-icons=$treeShakeIcons',
+      if (performanceMeasurementFile != null)
+        '-Pperformance-measurement-file=$performanceMeasurementFile',
+      if (bundleSkSLPath != null)
+        '-Pbundle-sksl-path=$bundleSkSLPath',
+      if (codeSizeDirectory != null)
+        '-Pcode-size-directory=$codeSizeDirectory',
+    ];
+  }
 }
 
 /// Information about an Android build to be performed or used.
@@ -737,9 +766,32 @@ String getFuchsiaBuildDirectory() {
 /// These values are URI-encoded and then combined into a comma-separated string.
 const String kDartDefines = 'DartDefines';
 
-/// Encode a List of dart defines in a URI string.
+final Converter<String, String> _defineEncoder = utf8.encoder.fuse(base64.encoder);
+final Converter<String, String> _defineDecoder = base64.decoder.fuse(utf8.decoder);
+
+/// Encode a List of dart defines in a base64 string.
+///
+/// This encoding does not include `,`, which is used to distinguish
+/// the individual entries, nor does it include `%` which is often a
+/// control character on windows command lines.
+///
+/// When decoding this string, it can be safely split on commas, since any
+/// user provided commans will still be encoded.
+///
+/// If the presence of the `/` character ends up being an issue, this can
+/// be changed to use base32 instead.
 String encodeDartDefines(List<String> defines) {
-  return defines.map(Uri.encodeComponent).join(',');
+  return defines.map(_defineEncoder.convert).join(',');
+}
+
+List<String> decodeCommaSeparated(Map<String, String> environmentDefines, String key) {
+  if (!environmentDefines.containsKey(key) || environmentDefines[key].isEmpty) {
+    return <String>[];
+  }
+  return environmentDefines[key]
+    .split(',')
+    .cast<String>()
+    .toList();
 }
 
 /// Dart defines are encoded inside [environmentDefines] as a comma-separated list.
@@ -749,7 +801,7 @@ List<String> decodeDartDefines(Map<String, String> environmentDefines, String ke
   }
   return environmentDefines[key]
     .split(',')
-    .map<Object>(Uri.decodeComponent)
+    .map<Object>(_defineDecoder.convert)
     .cast<String>()
     .toList();
 }

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

@@ -215,7 +215,7 @@ class AndroidAot extends AotElfBase {
     if (!output.existsSync()) {
       output.createSync(recursive: true);
     }
-    final List<String> extraGenSnapshotOptions = decodeDartDefines(environment.defines, kExtraGenSnapshotOptions);
+    final List<String> extraGenSnapshotOptions = decodeCommaSeparated(environment.defines, kExtraGenSnapshotOptions);
     final BuildMode buildMode = getBuildModeForName(environment.defines[kBuildMode]);
     final bool dartObfuscation = environment.defines[kDartObfuscation] == 'true';
     final String codeSizeDirectory = environment.defines[kCodeSizeDirectory];

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

@@ -227,7 +227,7 @@ class KernelSnapshot extends Target {
     final TargetPlatform targetPlatform = getTargetPlatformForName(environment.defines[kTargetPlatform]);
 
     // This configuration is all optional.
-    final List<String> extraFrontEndOptions = decodeDartDefines(environment.defines, kExtraFrontEndOptions);
+    final List<String> extraFrontEndOptions = decodeCommaSeparated(environment.defines, kExtraFrontEndOptions);
     final List<String> fileSystemRoots = environment.defines[kFileSystemRoots]?.split(',');
     final String fileSystemScheme = environment.defines[kFileSystemScheme];
 
@@ -306,7 +306,7 @@ abstract class AotElfBase extends Target {
     if (environment.defines[kTargetPlatform] == null) {
       throw MissingDefineException(kTargetPlatform, 'aot_elf');
     }
-    final List<String> extraGenSnapshotOptions = decodeDartDefines(environment.defines, kExtraGenSnapshotOptions);
+    final List<String> extraGenSnapshotOptions = decodeCommaSeparated(environment.defines, kExtraGenSnapshotOptions);
     final BuildMode buildMode = getBuildModeForName(environment.defines[kBuildMode]);
     final TargetPlatform targetPlatform = getTargetPlatformForName(environment.defines[kTargetPlatform]);
     final String splitDebugInfo = environment.defines[kSplitDebugInfo];

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

@@ -54,7 +54,7 @@ abstract class AotAssemblyBase extends Target {
       throw MissingDefineException(kSdkRoot, 'aot_assembly');
     }
 
-    final List<String> extraGenSnapshotOptions = decodeDartDefines(environment.defines, kExtraGenSnapshotOptions);
+    final List<String> extraGenSnapshotOptions = decodeCommaSeparated(environment.defines, kExtraGenSnapshotOptions);
     final bool bitcode = environment.defines[kBitcodeFlag] == 'true';
     final BuildMode buildMode = getBuildModeForName(environment.defines[kBuildMode]);
     final TargetPlatform targetPlatform = getTargetPlatformForName(environment.defines[kTargetPlatform]);

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

@@ -180,7 +180,7 @@ class CompileMacOSFramework extends Target {
     final String codeSizeDirectory = environment.defines[kCodeSizeDirectory];
     final String splitDebugInfo = environment.defines[kSplitDebugInfo];
     final bool dartObfuscation = environment.defines[kDartObfuscation] == 'true';
-    final List<String> extraGenSnapshotOptions = decodeDartDefines(environment.defines, kExtraGenSnapshotOptions);
+    final List<String> extraGenSnapshotOptions = decodeCommaSeparated(environment.defines, kExtraGenSnapshotOptions);
 
     if (codeSizeDirectory != null) {
       final File codeSizeFile = environment.fileSystem

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

@@ -202,7 +202,7 @@ class Dart2JSTarget extends Target {
       '--disable-dart-dev',
       globals.artifacts.getArtifactPath(Artifact.dart2jsSnapshot),
       '--libraries-spec=${globals.fs.path.join(globals.artifacts.getArtifactPath(Artifact.flutterWebSdk), 'libraries.json')}',
-      ...?decodeDartDefines(environment.defines, kExtraFrontEndOptions),
+      ...?decodeCommaSeparated(environment.defines, kExtraFrontEndOptions),
       if (nativeNullAssertions)
         '--native-null-assertions',
       if (buildMode == BuildMode.profile)

packages/flutter_tools/lib/src/commands/build_ios_framework.dart

@@ -20,7 +20,6 @@ import '../build_system/targets/common.dart';
 import '../build_system/targets/icon_tree_shaker.dart';
 import '../build_system/targets/ios.dart';
 import '../cache.dart';
-import '../convert.dart';
 import '../globals.dart' as globals;
 import '../macos/cocoapod_utils.dart';
 import '../plugins.dart';
@@ -367,7 +366,7 @@ end
             kBuildMode: getNameForBuildMode(buildInfo.mode),
             kTargetPlatform: getNameForTargetPlatform(TargetPlatform.ios),
             kIconTreeShakerFlag: buildInfo.treeShakeIcons.toString(),
-            kDartDefines: jsonEncode(buildInfo.dartDefines),
+            kDartDefines: encodeDartDefines(buildInfo.dartDefines),
             kBitcodeFlag: 'true',
             if (buildInfo?.extraGenSnapshotOptions?.isNotEmpty ?? false)
               kExtraGenSnapshotOptions:

packages/flutter_tools/lib/src/web/compile.dart

@@ -58,7 +58,7 @@ Future<void> buildWeb(
         if (serviceWorkerStrategy != null)
          kServiceWorkerStrategy: serviceWorkerStrategy,
         if (buildInfo.extraFrontEndOptions?.isNotEmpty ?? false)
-          kExtraFrontEndOptions: encodeDartDefines(buildInfo.extraFrontEndOptions),
+          kExtraFrontEndOptions: buildInfo.extraFrontEndOptions.join(','),
       },
       artifacts: globals.artifacts,
       fileSystem: globals.fs,

packages/flutter_tools/test/commands.shard/hermetic/build_linux_test.dart

@@ -368,10 +368,10 @@ ERROR: No file or variants found for asset: images/a_dot_burr.jpeg
     expect(configLines, containsAll(<String>[
       'file(TO_CMAKE_PATH "$_kTestFlutterRoot" FLUTTER_ROOT)',
       'file(TO_CMAKE_PATH "${fileSystem.currentDirectory.path}" PROJECT_DIR)',
-      '  "DART_DEFINES=foo.bar%3D2,fizz.far%3D3"',
+      '  "DART_DEFINES=Zm9vLmJhcj0y,Zml6ei5mYXI9Mw=="',
       '  "DART_OBFUSCATION=true"',
-      '  "EXTRA_FRONT_END_OPTIONS=--enable-experiment%3Dnon-nullable"',
-      '  "EXTRA_GEN_SNAPSHOT_OPTIONS=--enable-experiment%3Dnon-nullable"',
+      '  "EXTRA_FRONT_END_OPTIONS=--enable-experiment=non-nullable"',
+      '  "EXTRA_GEN_SNAPSHOT_OPTIONS=--enable-experiment=non-nullable"',
       '  "SPLIT_DEBUG_INFO=foo/"',
       '  "TRACK_WIDGET_CREATION=true"',
       '  "TREE_SHAKE_ICONS=true"',

packages/flutter_tools/test/commands.shard/hermetic/build_macos_test.dart

@@ -257,16 +257,21 @@ void main() {
       .readAsLinesSync();
 
     expect(contents, containsAll(<String>[
-      'DART_DEFINES=foo.bar%3D2,fizz.far%3D3',
+      'FLUTTER_APPLICATION_PATH=/',
+      'FLUTTER_TARGET=lib/other.dart',
+      'FLUTTER_BUILD_DIR=build',
+      'FLUTTER_BUILD_NAME=1.0.0',
+      'FLUTTER_BUILD_NUMBER=1',
+      'EXCLUDED_ARCHS=arm64',
+      'DART_DEFINES=Zm9vLmJhcj0y,Zml6ei5mYXI9Mw==',
       'DART_OBFUSCATION=true',
-      'EXTRA_FRONT_END_OPTIONS=--enable-experiment%3Dnon-nullable',
-      'EXTRA_GEN_SNAPSHOT_OPTIONS=--enable-experiment%3Dnon-nullable',
+      'EXTRA_FRONT_END_OPTIONS=--enable-experiment=non-nullable',
+      'EXTRA_GEN_SNAPSHOT_OPTIONS=--enable-experiment=non-nullable',
       'SPLIT_DEBUG_INFO=foo/',
       'TRACK_WIDGET_CREATION=true',
       'TREE_SHAKE_ICONS=true',
-      'FLUTTER_TARGET=lib/other.dart',
       'BUNDLE_SKSL_PATH=foo/bar.sksl.json',
-      'EXCLUDED_ARCHS=arm64',
+      'PACKAGE_CONFIG=/.dart_tool/package_config.json'
     ]));
   }, overrides: <Type, Generator>{
     FileSystem: () => fileSystem,

packages/flutter_tools/test/commands.shard/hermetic/build_windows_test.dart

@@ -317,10 +317,10 @@ C:\foo\windows\runner\main.cpp(17,1): error C2065: 'Baz': undeclared identifier
     expect(configLines, containsAll(<String>[
       r'file(TO_CMAKE_PATH "C:\\flutter" FLUTTER_ROOT)',
       r'file(TO_CMAKE_PATH "C:\\" PROJECT_DIR)',
-      r'  "DART_DEFINES=foo%3Da,bar%3Db"',
+      r'  "DART_DEFINES=Zm9vPWE=,YmFyPWI="',
       r'  "DART_OBFUSCATION=true"',
-      r'  "EXTRA_FRONT_END_OPTIONS=--enable-experiment%3Dnon-nullable"',
-      r'  "EXTRA_GEN_SNAPSHOT_OPTIONS=--enable-experiment%3Dnon-nullable"',
+      r'  "EXTRA_FRONT_END_OPTIONS=--enable-experiment=non-nullable"',
+      r'  "EXTRA_GEN_SNAPSHOT_OPTIONS=--enable-experiment=non-nullable"',
       r'  "SPLIT_DEBUG_INFO=C:\\foo\\"',
       r'  "TRACK_WIDGET_CREATION=true"',
       r'  "TREE_SHAKE_ICONS=true"',

packages/flutter_tools/test/commands.shard/permeable/build_apk_test.dart

@@ -237,6 +237,7 @@ void main() {
           '-q',
           '-Ptarget-platform=android-arm,android-arm64,android-x64',
           '-Ptarget=${globals.fs.path.join(tempDir.path, 'flutter_project', 'lib', 'main.dart')}',
+          '-Pdart-obfuscation=false',
           '-Ptrack-widget-creation=true',
           '-Ptree-shake-icons=true',
           'assembleRelease',
@@ -265,8 +266,9 @@ void main() {
           '-q',
           '-Ptarget-platform=android-arm,android-arm64,android-x64',
           '-Ptarget=${globals.fs.path.join(tempDir.path, 'flutter_project', 'lib', 'main.dart')}',
-          '-Ptrack-widget-creation=true',
+          '-Pdart-obfuscation=false',
           '-Psplit-debug-info=${tempDir.path}',
+          '-Ptrack-widget-creation=true',
           '-Ptree-shake-icons=true',
           'assembleRelease',
         ],
@@ -297,8 +299,9 @@ void main() {
           '-q',
           '-Ptarget-platform=android-arm,android-arm64,android-x64',
           '-Ptarget=${globals.fs.path.join(tempDir.path, 'flutter_project', 'lib', 'main.dart')}',
-          '-Ptrack-widget-creation=true',
+          '-Pdart-obfuscation=false',
           '-Pextra-front-end-options=foo,bar',
+          '-Ptrack-widget-creation=true',
           '-Ptree-shake-icons=true',
           'assembleRelease',
         ],
@@ -329,6 +332,7 @@ void main() {
           '-q',
           '-Ptarget-platform=android-arm,android-arm64,android-x64',
           '-Ptarget=${globals.fs.path.join(tempDir.path, 'flutter_project', 'lib', 'main.dart')}',
+          '-Pdart-obfuscation=false',
           '-Ptrack-widget-creation=true',
           '-Ptree-shake-icons=true',
           'assembleRelease',
@@ -353,6 +357,7 @@ void main() {
           '-q',
           '-Ptarget-platform=android-arm,android-arm64,android-x64',
           '-Ptarget=${globals.fs.path.join(tempDir.path, 'flutter_project', 'lib', 'main.dart')}',
+          '-Pdart-obfuscation=false',
           '-Ptrack-widget-creation=true',
           '-Ptree-shake-icons=true',
           'assembleRelease',
@@ -422,6 +427,7 @@ void main() {
           '-q',
           '-Ptarget-platform=android-arm,android-arm64,android-x64',
           '-Ptarget=${globals.fs.path.join(tempDir.path, 'flutter_project', 'lib', 'main.dart')}',
+          '-Pdart-obfuscation=false',
           '-Ptrack-widget-creation=true',
           '-Ptree-shake-icons=true',
           'assembleRelease',
@@ -481,6 +487,7 @@ void main() {
           '-q',
           '-Ptarget-platform=android-arm,android-arm64,android-x64',
           '-Ptarget=${globals.fs.path.join(tempDir.path, 'flutter_project', 'lib', 'main.dart')}',
+          '-Pdart-obfuscation=false',
           '-Ptrack-widget-creation=true',
           '-Ptree-shake-icons=true',
           'assembleRelease',

packages/flutter_tools/test/general.shard/android/gradle_test.dart

@@ -916,7 +916,9 @@ plugin2=${plugin2.path}
             '-Pis-plugin=true',
             '-PbuildNumber=1.0',
             '-q',
-            '-Pfont-subset=true',
+            '-Pdart-obfuscation=false',
+            '-Ptrack-widget-creation=false',
+            '-Ptree-shake-icons=true',
             '-Ptarget-platform=android-arm,android-arm64,android-x64',
             'assembleAarRelease',
           ],
@@ -931,7 +933,9 @@ plugin2=${plugin2.path}
             '-Pis-plugin=true',
             '-PbuildNumber=1.0',
             '-q',
-            '-Pfont-subset=true',
+            '-Pdart-obfuscation=false',
+            '-Ptrack-widget-creation=false',
+            '-Ptree-shake-icons=true',
             '-Ptarget-platform=android-arm,android-arm64,android-x64',
             'assembleAarRelease',
           ],
@@ -2103,7 +2107,9 @@ plugin1=${plugin1.path}
           '--no-daemon',
           '-Ptarget-platform=android-arm,android-arm64,android-x64',
           '-Ptarget=lib/main.dart',
+          '-Pdart-obfuscation=false',
           '-Ptrack-widget-creation=false',
+          '-Ptree-shake-icons=false',
           'assembleRelease'
         ],
       ));

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

@@ -115,40 +115,67 @@ void main() {
     expect(buildInfo.toEnvironmentConfig(), <String, String>{
       'TREE_SHAKE_ICONS': 'true',
       'TRACK_WIDGET_CREATION': 'true',
-      'DART_DEFINES': 'foo%3D2,bar%3D2',
+      'DART_DEFINES': 'Zm9vPTI=,YmFyPTI=',
       'DART_OBFUSCATION': 'true',
       'SPLIT_DEBUG_INFO': 'foo/',
-      'EXTRA_FRONT_END_OPTIONS': '--enable-experiment%3Dnon-nullable,bar',
-      'EXTRA_GEN_SNAPSHOT_OPTIONS': '--enable-experiment%3Dnon-nullable,fizz',
+      'EXTRA_FRONT_END_OPTIONS': '--enable-experiment=non-nullable,bar',
+      'EXTRA_GEN_SNAPSHOT_OPTIONS': '--enable-experiment=non-nullable,fizz',
       'BUNDLE_SKSL_PATH': 'foo/bar/baz.sksl.json',
       'PACKAGE_CONFIG': 'foo/.packages',
       'CODE_SIZE_DIRECTORY': 'foo/code-size',
     });
   });
 
-  testWithoutContext('encodeDartDefines encodes define values with URI encode compnents', () {
-    expect(encodeDartDefines(<String>['"hello"']), '%22hello%22');
-    expect(encodeDartDefines(<String>['https://www.google.com']), 'https%3A%2F%2Fwww.google.com');
-    expect(encodeDartDefines(<String>['2,3,4', '5']), '2%2C3%2C4,5');
-    expect(encodeDartDefines(<String>['true', 'false', 'flase']), 'true,false,flase');
-    expect(encodeDartDefines(<String>['1232,456', '2']), '1232%2C456,2');
+  testWithoutContext('toGradleConfig encoding of standard values', () {
+    const BuildInfo buildInfo = BuildInfo(BuildMode.debug, '',
+      treeShakeIcons: true,
+      trackWidgetCreation: true,
+      dartDefines: <String>['foo=2', 'bar=2'],
+      dartObfuscation: true,
+      splitDebugInfoPath: 'foo/',
+      extraFrontEndOptions: <String>['--enable-experiment=non-nullable', 'bar'],
+      extraGenSnapshotOptions: <String>['--enable-experiment=non-nullable', 'fizz'],
+      bundleSkSLPath: 'foo/bar/baz.sksl.json',
+      packagesPath: 'foo/.packages',
+      codeSizeDirectory: 'foo/code-size',
+    );
+
+    expect(buildInfo.toGradleConfig(), <String>[
+      '-Pdart-defines=Zm9vPTI=,YmFyPTI=',
+      '-Pdart-obfuscation=true',
+      '-Pextra-front-end-options=--enable-experiment=non-nullable,bar',
+      '-Pextra-gen-snapshot-options=--enable-experiment=non-nullable,fizz',
+      '-Psplit-debug-info=foo/',
+      '-Ptrack-widget-creation=true',
+      '-Ptree-shake-icons=true',
+      '-Pbundle-sksl-path=foo/bar/baz.sksl.json',
+      '-Pcode-size-directory=foo/code-size'
+    ]);
+  });
+
+  testWithoutContext('encodeDartDefines encodes define values with base64 encoded compnents', () {
+    expect(encodeDartDefines(<String>['"hello"']), 'ImhlbGxvIg==');
+    expect(encodeDartDefines(<String>['https://www.google.com']), 'aHR0cHM6Ly93d3cuZ29vZ2xlLmNvbQ==');
+    expect(encodeDartDefines(<String>['2,3,4', '5']), 'MiwzLDQ=,NQ==');
+    expect(encodeDartDefines(<String>['true', 'false', 'flase']), 'dHJ1ZQ==,ZmFsc2U=,Zmxhc2U=');
+    expect(encodeDartDefines(<String>['1232,456', '2']), 'MTIzMiw0NTY=,Mg==');
   });
 
-  testWithoutContext('decodeDartDefines decodes URI encoded dart defines', () {
+  testWithoutContext('decodeDartDefines decodes base64 encoded dart defines', () {
     expect(decodeDartDefines(<String, String>{
-      kDartDefines: '%22hello%22'
+      kDartDefines: 'ImhlbGxvIg=='
     }, kDartDefines), <String>['"hello"']);
     expect(decodeDartDefines(<String, String>{
-      kDartDefines: 'https%3A%2F%2Fwww.google.com'
+      kDartDefines: 'aHR0cHM6Ly93d3cuZ29vZ2xlLmNvbQ=='
     }, kDartDefines), <String>['https://www.google.com']);
     expect(decodeDartDefines(<String, String>{
-      kDartDefines: '2%2C3%2C4,5'
+      kDartDefines: 'MiwzLDQ=,NQ=='
     }, kDartDefines), <String>['2,3,4', '5']);
     expect(decodeDartDefines(<String, String>{
-      kDartDefines: 'true,false,flase'
+      kDartDefines: 'dHJ1ZQ==,ZmFsc2U=,Zmxhc2U='
     }, kDartDefines), <String>['true', 'false', 'flase']);
     expect(decodeDartDefines(<String, String>{
-      kDartDefines: '1232%2C456,2'
+      kDartDefines: 'MTIzMiw0NTY=,Mg=='
     }, kDartDefines), <String>['1232,456', '2']);
   });
 }

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

@@ -481,7 +481,7 @@ void main() {
 
   test('Dart2JSTarget calls dart2js with Dart defines in release mode', () => testbed.run(() async {
     environment.defines[kBuildMode] = 'release';
-    environment.defines[kDartDefines] = 'FOO=bar,BAZ=qux';
+    environment.defines[kDartDefines] = encodeDartDefines(<String>['FOO=bar', 'BAZ=qux']);
     processManager.addCommand(FakeCommand(
       command: <String>[
         ...kDart2jsLinuxArgs,
@@ -548,7 +548,7 @@ void main() {
 
   test('Dart2JSTarget calls dart2js with Dart defines in profile mode', () => testbed.run(() async {
     environment.defines[kBuildMode] = 'profile';
-    environment.defines[kDartDefines] = 'FOO=bar,BAZ=qux';
+    environment.defines[kDartDefines] = encodeDartDefines(<String>['FOO=bar', 'BAZ=qux']);
     processManager.addCommand(FakeCommand(
       command: <String>[
         ...kDart2jsLinuxArgs,