Implementing control flow collections (#146601)

This pull request aims for improved readability, based on issue #146600.

```dart
// before
Set<Color> _distinctVisibleColors() {
  final Set<Color> distinctVisibleColors = <Color>{};
  if (top.style != BorderStyle.none) {
    distinctVisibleColors.add(top.color);
  }
  if (right.style != BorderStyle.none) {
    distinctVisibleColors.add(right.color);
  }
  if (bottom.style != BorderStyle.none) {
    distinctVisibleColors.add(bottom.color);
  }
  if (left.style != BorderStyle.none) {
    distinctVisibleColors.add(left.color);
  }
  return distinctVisibleColors;
}

// after
Set<Color> _distinctVisibleColors() {
  return <Color>{
    if (top.style != BorderStyle.none) top.color,
    if (right.style != BorderStyle.none) right.color,
    if (bottom.style != BorderStyle.none) bottom.color,
    if (left.style != BorderStyle.none) left.color,
  };
}
```

Most of the repo should be covered in this PR (aside from `flutter_tools/`, since there was a lot going on in there).

dev/benchmarks/platform_channels_benchmarks/lib/main.dart

@@ -11,30 +11,20 @@ import 'package:flutter/services.dart';
 import 'package:microbenchmarks/common.dart';
 
 List<Object?> _makeTestBuffer(int size) {
-  final List<Object?> answer = <Object?>[];
+  return <Object?>[
-  for (int i = 0; i < size; ++i) {
+    for (int i = 0; i < size; i++)
-    switch (i % 9) {
+      switch (i % 9) {
-      case 0:
+        0 => 1,
-        answer.add(1);
+        1 => math.pow(2, 65),
-      case 1:
+        2 => 1234.0,
-        answer.add(math.pow(2, 65));
+        3 => null,
-      case 2:
+        4 => <int>[1234],
-        answer.add(1234.0);
+        5 => <String, int>{'hello': 1234},
-      case 3:
+        6 => 'this is a test',
-        answer.add(null);
+        7 => true,
-      case 4:
+        _ => Uint8List(64),
-        answer.add(<int>[1234]);
+      },
-      case 5:
+  ];
-        answer.add(<String, int>{'hello': 1234});
-      case 6:
-        answer.add('this is a test');
-      case 7:
-        answer.add(true);
-      case 8:
-        answer.add(Uint8List(64));
-    }
-  }
-  return answer;
 }
 
 Future<double> _runBasicStandardSmall(

dev/bots/suite_runners/run_verify_binaries_codesigned_tests.dart

@@ -139,28 +139,21 @@ Future<void> verifyExist(
   String flutterRoot,
   {@visibleForTesting ProcessManager processManager = const LocalProcessManager()
 }) async {
-  final Set<String> foundFiles = <String>{};
+  final List<String> binaryPaths = await findBinaryPaths(
-  final String cacheDirectory =  path.join(flutterRoot, 'bin', 'cache');
+    path.join(flutterRoot, 'bin', 'cache'),
-
+    processManager: processManager,
-  for (final String binaryPath
+  );
-      in await findBinaryPaths(cacheDirectory, processManager: processManager)) {
-    if (binariesWithEntitlements(flutterRoot).contains(binaryPath)) {
-      foundFiles.add(binaryPath);
-    } else if (binariesWithoutEntitlements(flutterRoot).contains(binaryPath)) {
-      foundFiles.add(binaryPath);
-    } else {
-      throw Exception(
-          'Found unexpected binary in cache: $binaryPath');
-    }
-  }
-
   final List<String> allExpectedFiles = binariesWithEntitlements(flutterRoot) + binariesWithoutEntitlements(flutterRoot);
+  final Set<String> foundFiles = <String>{
+    for (final String binaryPath in binaryPaths)
+      if (allExpectedFiles.contains(binaryPath)) binaryPath
+      else throw Exception('Found unexpected binary in cache: $binaryPath'),
+  };
+
   if (foundFiles.length < allExpectedFiles.length) {
-    final List<String> unfoundFiles = allExpectedFiles
+    final List<String> unfoundFiles = <String>[
-        .where(
+      for (final String file in allExpectedFiles) if (!foundFiles.contains(file)) file,
-          (String file) => !foundFiles.contains(file),
+    ];
-        )
-        .toList();
     print(
       'Expected binaries not found in cache:\n\n${unfoundFiles.join('\n')}\n\n'
       'If this commit is removing binaries from the cache, this test should be fixed by\n'

dev/bots/test.dart

@@ -913,18 +913,14 @@ Future<void> _runFrameworkTests() async {
         final Uint8List libappBytes = libapp.content as Uint8List; // bytes decompressed here
         final String libappStrings = utf8.decode(libappBytes, allowMalformed: true);
         await runCommand(flutter, <String>['clean'], workingDirectory: tracingDirectory);
-        final List<String> results = <String>[];
+        return <String>[
-        for (final String pattern in allowed) {
+          for (final String pattern in allowed)
-          if (!libappStrings.contains(pattern)) {
+            if (!libappStrings.contains(pattern))
-            results.add('When building with --$modeArgument, expected to find "$pattern" in libapp.so but could not find it.');
+              'When building with --$modeArgument, expected to find "$pattern" in libapp.so but could not find it.',
-          }
+          for (final String pattern in disallowed)
-        }
+            if (libappStrings.contains(pattern))
-        for (final String pattern in disallowed) {
+              'When building with --$modeArgument, expected to not find "$pattern" in libapp.so but did find it.',
-          if (libappStrings.contains(pattern)) {
+        ];
-            results.add('When building with --$modeArgument, expected to not find "$pattern" in libapp.so but did find it.');
-          }
-        }
-        return results;
       } catch (error, stackTrace) {
         return <String>[
           error.toString(),
@@ -1332,11 +1328,9 @@ Future<void> _runDartTest(String workingDirectory, {
 
   if (collectMetrics) {
     try {
-      final List<String> testList = <String>[];
+      final List<String> testList = <String>[
-      final Map<int, TestSpecs> allTestSpecs = test.allTestSpecs;
+        for (final TestSpecs testSpecs in test.allTestSpecs.values) testSpecs.toJson(),
-      for (final TestSpecs testSpecs in allTestSpecs.values) {
+      ];
-        testList.add(testSpecs.toJson());
-      }
       if (testList.isNotEmpty) {
         final String testJson = json.encode(testList);
         final File testResults = fileSystem.file(

dev/conductor/core/lib/src/next.dart

@@ -110,12 +110,10 @@ class NextContext extends Context {
           break;
         }
 
-        final List<pb.Cherrypick> unappliedCherrypicks = <pb.Cherrypick>[];
+        final List<pb.Cherrypick> unappliedCherrypicks = <pb.Cherrypick>[
-        for (final pb.Cherrypick cherrypick in state.engine.cherrypicks) {
+          for (final pb.Cherrypick cherrypick in state.engine.cherrypicks)
-          if (!finishedStates.contains(cherrypick.state)) {
+            if (!finishedStates.contains(cherrypick.state)) cherrypick,
-            unappliedCherrypicks.add(cherrypick);
+        ];
-          }
-        }
 
         if (unappliedCherrypicks.isEmpty) {
           stdio.printStatus('All engine cherrypicks have been auto-applied by the conductor.\n');
@@ -206,12 +204,10 @@ class NextContext extends Context {
           );
         }
 
-        final List<pb.Cherrypick> unappliedCherrypicks = <pb.Cherrypick>[];
+        final List<pb.Cherrypick> unappliedCherrypicks = <pb.Cherrypick>[
-        for (final pb.Cherrypick cherrypick in state.framework.cherrypicks) {
+          for (final pb.Cherrypick cherrypick in state.framework.cherrypicks)
-          if (!finishedStates.contains(cherrypick.state)) {
+            if (!finishedStates.contains(cherrypick.state)) cherrypick,
-            unappliedCherrypicks.add(cherrypick);
+        ];
-          }
-        }
 
         if (state.framework.cherrypicks.isEmpty) {
           stdio.printStatus(

dev/conductor/core/lib/src/repository.dart

@@ -183,15 +183,11 @@ abstract class Repository {
       workingDirectory: (await checkoutDirectory).path,
     );
 
-    final List<String> remoteBranches = <String>[];
+    return <String>[
-    for (final String line in output.split('\n')) {
+      for (final String line in output.split('\n'))
-      final RegExpMatch? match = _lsRemotePattern.firstMatch(line);
+        if (_lsRemotePattern.firstMatch(line) case final RegExpMatch match)
-      if (match != null) {
+          match.group(1)!,
-        remoteBranches.add(match.group(1)!);
+    ];
-      }
-    }
-
-    return remoteBranches;
   }
 
   /// Ensure the repository is cloned to disk and initialized with proper state.

dev/devicelab/lib/tasks/microbenchmarks.dart

@@ -39,8 +39,8 @@ TaskFunction createMicrobenchmarkTask({
             if (enableImpeller != null && !enableImpeller) '--no-enable-impeller',
             '-d',
             device.deviceId,
+            benchmarkPath,
           ];
-          options.add(benchmarkPath);
           return startFlutter(
             'run',
             options: options,

dev/integration_tests/android_semantics_testing/lib/src/common.dart

@@ -154,14 +154,11 @@ class AndroidSemanticsNode {
     if (actions == null) {
       return const <AndroidSemanticsAction>[];
     }
-    final List<AndroidSemanticsAction> convertedActions = <AndroidSemanticsAction>[];
+    return <AndroidSemanticsAction>[
-    for (final int id in actions) {
+      for (final int id in actions)
-      final AndroidSemanticsAction? action = AndroidSemanticsAction.deserialize(id);
+        if (AndroidSemanticsAction.deserialize(id) case final AndroidSemanticsAction action)
-      if (action != null) {
+          action,
-        convertedActions.add(action);
+    ];
-      }
-    }
-    return convertedActions;
   }
 
   @override

dev/integration_tests/flutter_gallery/lib/demo/calculator/logic.dart

@@ -121,10 +121,8 @@ class CalcExpression {
     : this(<ExpressionToken>[], ExpressionState.Start);
 
   CalcExpression.result(FloatToken result)
-    : _list = <ExpressionToken?>[],
+    : _list = <ExpressionToken?>[result],
-      state = ExpressionState.Result {
+      state = ExpressionState.Result;
-    _list.add(result);
-  }
 
   /// The tokens comprising the expression.
   final List<ExpressionToken?> _list;

dev/integration_tests/new_gallery/lib/demos/cupertino/cupertino_search_text_field_demo.dart

@@ -84,15 +84,11 @@ class _CupertinoSearchTextFieldDemoState
 
   Widget _buildPlatformList() {
     if (_searchPlatform.isNotEmpty) {
-      final List<String> tempList = <String>[];
+      final String search = _searchPlatform.toLowerCase();
-      for (int i = 0; i < filteredPlatforms.length; i++) {
+      filteredPlatforms = <String>[
-        if (filteredPlatforms[i]
+        for (final String platform in filteredPlatforms)
-            .toLowerCase()
+          if (platform.toLowerCase().contains(search)) platform
-            .contains(_searchPlatform.toLowerCase())) {
+      ];
-          tempList.add(filteredPlatforms[i]);
-        }
-      }
-      filteredPlatforms = tempList;
     }
     return ListView.builder(
       itemCount: filteredPlatforms.length,

dev/integration_tests/new_gallery/lib/demos/material/data_table_demo.dart

@@ -26,14 +26,10 @@ class _RestorableDessertSelections extends RestorableProperty<Set<int>> {
   /// Takes a list of [_Dessert]s and saves the row indices of selected rows
   /// into a [Set].
   void setDessertSelections(List<_Dessert> desserts) {
-    final Set<int> updatedSet = <int>{};
+    _dessertSelections = <int>{
-    for (int i = 0; i < desserts.length; i += 1) {
+      for (final (int i, _Dessert dessert) in desserts.indexed)
-      final _Dessert dessert = desserts[i];
+        if (dessert.selected) i,
-      if (dessert.selected) {
+    };
-        updatedSet.add(i);
-      }
-    }
-    _dessertSelections = updatedSet;
     notifyListeners();
   }
 

dev/tools/examples_smoke_test.dart

@@ -116,19 +116,18 @@ Future<File> generateTest(Directory apiDir) async {
   });
 
   // Collect the examples, and import them all as separate symbols.
-  final List<String> imports = <String>[];
+  final List<ExampleInfo> infoList = <ExampleInfo>[
-  imports.add('''import 'package:flutter/widgets.dart';''');
+    for (final File example in examples) ExampleInfo(example, examplesLibDir),
-  imports.add('''import 'package:flutter/scheduler.dart';''');
+  ];
-  imports.add('''import 'package:flutter_test/flutter_test.dart';''');
-  imports.add('''import 'package:integration_test/integration_test.dart';''');
-  final List<ExampleInfo> infoList = <ExampleInfo>[];
-  for (final File example in examples) {
-    final ExampleInfo info = ExampleInfo(example, examplesLibDir);
-    infoList.add(info);
-    imports.add('''import 'package:flutter_api_samples/${info.importPath}' as ${info.importName};''');
-  }
-  imports.sort();
   infoList.sort((ExampleInfo a, ExampleInfo b) => a.importPath.compareTo(b.importPath));
+  final List<String> imports = <String>[
+    "import 'package:flutter/widgets.dart';",
+    "import 'package:flutter/scheduler.dart';",
+    "import 'package:flutter_test/flutter_test.dart';",
+    "import 'package:integration_test/integration_test.dart';",
+    for (final ExampleInfo info in infoList)
+      "import 'package:flutter_api_samples/${info.importPath}' as ${info.importName};"
+  ]..sort();
 
   final StringBuffer buffer = StringBuffer();
   buffer.writeln('// Temporary generated file. Do not commit.');

dev/tools/update_icons.dart

@@ -388,15 +388,10 @@ bool testIsSuperset(Map<String, String> newCodepoints, Map<String, String> oldCo
 @visibleForTesting
 bool testIsStable(Map<String, String> newCodepoints, Map<String, String> oldCodepoints) {
   final int oldCodepointsCount = oldCodepoints.length;
-  final List<String> unstable = <String>[];
+  final List<String> unstable = <String>[
-
+    for (final MapEntry<String, String>(:String key, :String value) in oldCodepoints.entries)
-  oldCodepoints.forEach((String key, String value) {
+      if (newCodepoints.containsKey(key) && value != newCodepoints[key]) key,
-    if (newCodepoints.containsKey(key)) {
+  ];
-      if (value != newCodepoints[key]) {
-        unstable.add(key);
-      }
-    }
-  });
 
   if (unstable.isNotEmpty) {
     stderr.writeln('❌ out of $oldCodepointsCount existing codepoints, ${unstable.length} were unstable: $unstable');

packages/flutter/lib/src/cupertino/dialog.dart

@@ -1485,22 +1485,15 @@ class _CupertinoAlertActionSection extends StatelessWidget {
 
   @override
   Widget build(BuildContext context) {
-
-    final List<Widget> interactiveButtons = <Widget>[];
-    for (int i = 0; i < children.length; i += 1) {
-      interactiveButtons.add(
-        _PressableActionButton(
-          child: children[i],
-        ),
-      );
-    }
-
     return CupertinoScrollbar(
       controller: scrollController,
       child: SingleChildScrollView(
         controller: scrollController,
         child: _CupertinoDialogActionsRenderWidget(
-          actionButtons: interactiveButtons,
+          actionButtons: <Widget>[
+            for (final Widget child in children)
+              _PressableActionButton(child: child),
+          ],
           dividerThickness: _kDividerThickness,
           hasCancelButton: hasCancelButton,
           isActionSheet: isActionSheet,

packages/flutter/lib/src/foundation/timeline.dart

@@ -311,12 +311,10 @@ final class _Float64ListChain {
   /// are read back, they do not affect the timings of the work being
   /// benchmarked.
   List<double> extractElements() {
-    final List<double> result = <double>[];
+    return <double>[
-    _chain.forEach(result.addAll);
+      for (final Float64List list in _chain) ...list,
-    for (int i = 0; i < _pointer; i++) {
+      for (int i = 0; i < _pointer; i++) _slice[i],
-      result.add(_slice[i]);
+    ];
-    }
-    return result;
   }
 }
 
@@ -349,16 +347,11 @@ final class _StringListChain {
   /// are read back, they do not affect the timings of the work being
   /// benchmarked.
   List<String> extractElements() {
-    final List<String> result = <String>[];
+    return <String>[
-    for (final List<String?> slice in _chain) {
+      for (final List<String?> slice in _chain)
-      for (final String? element in slice) {
+        for (final String? value in slice) value!,
-        result.add(element!);
+      for (int i = 0; i < _pointer; i++) _slice[i]!,
-      }
+    ];
-    }
-    for (int i = 0; i < _pointer; i++) {
-      result.add(_slice[i]!);
-    }
-    return result;
   }
 }
 

packages/flutter/lib/src/material/menu_anchor.dart

@@ -2125,37 +2125,22 @@ class _LocalizedShortcutLabeler {
         keySeparator = '+';
     }
     if (serialized.trigger != null) {
-      final List<String> modifiers = <String>[];
       final LogicalKeyboardKey trigger = serialized.trigger!;
-      if (_usesSymbolicModifiers) {
+      final List<String> modifiers = <String>[
-        // macOS/iOS platform convention uses this ordering, with ⌘ always last.
+        if (_usesSymbolicModifiers) ...<String>[
-        if (serialized.control!) {
+          // MacOS/iOS platform convention uses this ordering, with ⌘ always last.
-          modifiers.add(_getModifierLabel(LogicalKeyboardKey.control, localizations));
+          if (serialized.control!) _getModifierLabel(LogicalKeyboardKey.control, localizations),
-        }
+          if (serialized.alt!)     _getModifierLabel(LogicalKeyboardKey.alt, localizations),
-        if (serialized.alt!) {
+          if (serialized.shift!)   _getModifierLabel(LogicalKeyboardKey.shift, localizations),
-          modifiers.add(_getModifierLabel(LogicalKeyboardKey.alt, localizations));
+          if (serialized.meta!)    _getModifierLabel(LogicalKeyboardKey.meta, localizations),
-        }
+        ] else ...<String>[
-        if (serialized.shift!) {
+          // This order matches the LogicalKeySet version.
-          modifiers.add(_getModifierLabel(LogicalKeyboardKey.shift, localizations));
+          if (serialized.alt!)     _getModifierLabel(LogicalKeyboardKey.alt, localizations),
-        }
+          if (serialized.control!) _getModifierLabel(LogicalKeyboardKey.control, localizations),
-        if (serialized.meta!) {
+          if (serialized.meta!)    _getModifierLabel(LogicalKeyboardKey.meta, localizations),
-          modifiers.add(_getModifierLabel(LogicalKeyboardKey.meta, localizations));
+          if (serialized.shift!)   _getModifierLabel(LogicalKeyboardKey.shift, localizations),
-        }
+        ],
-      } else {
+      ];
-        // These should be in this order, to match the LogicalKeySet version.
-        if (serialized.alt!) {
-          modifiers.add(_getModifierLabel(LogicalKeyboardKey.alt, localizations));
-        }
-        if (serialized.control!) {
-          modifiers.add(_getModifierLabel(LogicalKeyboardKey.control, localizations));
-        }
-        if (serialized.meta!) {
-          modifiers.add(_getModifierLabel(LogicalKeyboardKey.meta, localizations));
-        }
-        if (serialized.shift!) {
-          modifiers.add(_getModifierLabel(LogicalKeyboardKey.shift, localizations));
-        }
-      }
       String? shortcutTrigger;
       final int logicalKeyId = trigger.keyId;
       if (_shortcutGraphicEquivalents.containsKey(trigger)) {

packages/flutter/lib/src/material/navigation_drawer.dart

@@ -141,7 +141,6 @@ class NavigationDrawer extends StatelessWidget {
         children.whereType<NavigationDrawerDestination>().toList().length;
 
     int destinationIndex = 0;
-    final List<Widget> wrappedChildren = <Widget>[];
     Widget wrapChild(Widget child, int index) => _SelectableAnimatedBuilder(
         duration: const Duration(milliseconds: 500),
         isSelected: index == selectedIndex,
@@ -162,14 +161,11 @@ class NavigationDrawer extends StatelessWidget {
           );
         });
 
-    for (int i = 0; i < children.length; i++) {
+    final List<Widget> wrappedChildren = <Widget>[
-      if (children[i] is! NavigationDrawerDestination) {
+      for (final Widget child in children)
-        wrappedChildren.add(children[i]);
+        if (child is! NavigationDrawerDestination) child
-      } else {
+        else wrapChild(child, destinationIndex++),
-        wrappedChildren.add(wrapChild(children[i], destinationIndex));
+    ];
-        destinationIndex += 1;
-      }
-    }
     final NavigationDrawerThemeData navigationDrawerTheme = NavigationDrawerTheme.of(context);
 
     return Drawer(

packages/flutter/lib/src/painting/box_border.dart

@@ -492,20 +492,12 @@ class Border extends BoxBorder {
   }
 
   Set<Color> _distinctVisibleColors() {
-    final Set<Color> distinctVisibleColors = <Color>{};
+    return <Color>{
-    if (top.style != BorderStyle.none) {
+      if (top.style != BorderStyle.none) top.color,
-      distinctVisibleColors.add(top.color);
+      if (right.style != BorderStyle.none) right.color,
-    }
+      if (bottom.style != BorderStyle.none) bottom.color,
-    if (right.style != BorderStyle.none) {
+      if (left.style != BorderStyle.none) left.color,
-      distinctVisibleColors.add(right.color);
+    };
-    }
-    if (bottom.style != BorderStyle.none) {
-      distinctVisibleColors.add(bottom.color);
-    }
-    if (left.style != BorderStyle.none) {
-      distinctVisibleColors.add(left.color);
-    }
-    return distinctVisibleColors;
   }
 
   // [BoxBorder.paintNonUniformBorder] is about 20% faster than [paintBorder],
@@ -840,21 +832,12 @@ class BorderDirectional extends BoxBorder {
   }
 
   Set<Color> _distinctVisibleColors() {
-    final Set<Color> distinctVisibleColors = <Color>{};
+    return <Color>{
-    if (top.style != BorderStyle.none) {
+      if (top.style != BorderStyle.none) top.color,
-      distinctVisibleColors.add(top.color);
+      if (end.style != BorderStyle.none) end.color,
-    }
+      if (bottom.style != BorderStyle.none) bottom.color,
-    if (end.style != BorderStyle.none) {
+      if (start.style != BorderStyle.none) start.color,
-      distinctVisibleColors.add(end.color);
+    };
-    }
-    if (bottom.style != BorderStyle.none) {
-      distinctVisibleColors.add(bottom.color);
-    }
-    if (start.style != BorderStyle.none) {
-      distinctVisibleColors.add(start.color);
-    }
-
-    return distinctVisibleColors;
   }
 
 

packages/flutter/lib/src/rendering/table.dart

@@ -1260,19 +1260,13 @@ class RenderTable extends RenderBox {
       return <DiagnosticsNode>[DiagnosticsNode.message('table is empty')];
     }
 
-    final List<DiagnosticsNode> children = <DiagnosticsNode>[];
+    return <DiagnosticsNode>[
-    for (int y = 0; y < rows; y += 1) {
+      for (int y = 0; y < rows; y += 1)
-      for (int x = 0; x < columns; x += 1) {
+        for (int x = 0; x < columns; x += 1)
-        final int xy = x + y * columns;
+          if (_children[x + y * columns] case final RenderBox child)
-        final RenderBox? child = _children[xy];
+            child.toDiagnosticsNode(name: 'child ($x, $y)')
-        final String name = 'child ($x, $y)';
+          else
-        if (child != null) {
+            DiagnosticsProperty<Object>('child ($x, $y)', null, ifNull: 'is null', showSeparator: false),
-          children.add(child.toDiagnosticsNode(name: name));
+    ];
-        } else {
-          children.add(DiagnosticsProperty<Object>(name, null, ifNull: 'is null', showSeparator: false));
-        }
-      }
-    }
-    return children;
   }
 }

packages/flutter/lib/src/services/binding.dart

@@ -205,20 +205,15 @@ mixin ServicesBinding on BindingBase, SchedulerBinding {
   // This is run in another isolate created by _addLicenses above.
   static List<LicenseEntry> _parseLicenses(String rawLicenses) {
     final String licenseSeparator = '\n${'-' * 80}\n';
-    final List<LicenseEntry> result = <LicenseEntry>[];
+    return <LicenseEntry>[
-    final List<String> licenses = rawLicenses.split(licenseSeparator);
+      for (final String license in rawLicenses.split(licenseSeparator))
-    for (final String license in licenses) {
+        if (license.indexOf('\n\n') case final int split when split >= 0)
-      final int split = license.indexOf('\n\n');
+          LicenseEntryWithLineBreaks(
-      if (split >= 0) {
+            license.substring(0, split).split('\n'),
-        result.add(LicenseEntryWithLineBreaks(
+            license.substring(split + 2),
-          license.substring(0, split).split('\n'),
+          )
-          license.substring(split + 2),
+        else LicenseEntryWithLineBreaks(const <String>[], license),
-        ));
+    ];
-      } else {
-        result.add(LicenseEntryWithLineBreaks(const <String>[], license));
-      }
-    }
-    return result;
   }
 
   @override

packages/flutter/lib/src/services/hardware_keyboard.dart

@@ -625,14 +625,13 @@ class HardwareKeyboard {
   }
 
   List<String> _debugPressedKeysDetails() {
-    if (_pressedKeys.isEmpty) {
+    return <String>[
-      return <String>['Empty'];
+      if (_pressedKeys.isEmpty)
-    }
+        'Empty'
-    final List<String> details = <String>[];
+      else
-    for (final PhysicalKeyboardKey physicalKey in _pressedKeys.keys) {
+        for (final PhysicalKeyboardKey physicalKey in _pressedKeys.keys)
-      details.add('$physicalKey: ${_pressedKeys[physicalKey]}');
+          '$physicalKey: ${_pressedKeys[physicalKey]}',
-    }
+    ];
-    return details;
   }
 
   /// Process a new [KeyEvent] by recording the state changes and dispatching

packages/flutter/lib/src/services/spell_check.dart

@@ -180,20 +180,13 @@ class DefaultSpellCheckService implements SpellCheckService {
       return null;
     }
 
-    List<SuggestionSpan> suggestionSpans = <SuggestionSpan>[];
+    List<SuggestionSpan> suggestionSpans = <SuggestionSpan>[
-
+      for (final Map<dynamic, dynamic> resultMap in rawResults.cast<Map<dynamic, dynamic>>())
-    for (final dynamic result in rawResults) {
-      final Map<String, dynamic> resultMap =
-        Map<String,dynamic>.from(result as Map<dynamic, dynamic>);
-      suggestionSpans.add(
         SuggestionSpan(
-          TextRange(
+          TextRange(start: resultMap['startIndex'] as int, end: resultMap['endIndex'] as int),
-            start: resultMap['startIndex'] as int,
+          (resultMap['suggestions'] as List<Object?>).cast<String>(),
-            end: resultMap['endIndex'] as int),
+        ),
-          (resultMap['suggestions'] as List<dynamic>).cast<String>(),
+    ];
-        )
-      );
-    }
 
     if (lastSavedResults != null) {
       // Merge current and previous spell check results if between requests,

packages/flutter/lib/src/services/text_input.dart

@@ -1894,14 +1894,11 @@ class TextInput {
         TextInput._instance._updateEditingValue(value, exclude: _PlatformTextInputControl.instance);
       case 'TextInputClient.updateEditingStateWithDeltas':
         assert(_currentConnection!._client is DeltaTextInputClient, 'You must be using a DeltaTextInputClient if TextInputConfiguration.enableDeltaModel is set to true');
-        final List<TextEditingDelta> deltas = <TextEditingDelta>[];
-
         final Map<String, dynamic> encoded = args[1] as Map<String, dynamic>;
-
+        final List<TextEditingDelta> deltas = <TextEditingDelta>[
-        for (final dynamic encodedDelta in encoded['deltas'] as List<dynamic>) {
+          for (final dynamic encodedDelta in encoded['deltas'] as List<dynamic>)
-          final TextEditingDelta delta = TextEditingDelta.fromJSON(encodedDelta as Map<String, dynamic>);
+            TextEditingDelta.fromJSON(encodedDelta as Map<String, dynamic>)
-          deltas.add(delta);
+        ];
-        }
 
         (_currentConnection!._client as DeltaTextInputClient).updateEditingValueWithDeltas(deltas);
       case 'TextInputClient.performAction':

packages/flutter/lib/src/widgets/basic.dart

@@ -6686,16 +6686,11 @@ class MouseRegion extends SingleChildRenderObjectWidget {
   @override
   void debugFillProperties(DiagnosticPropertiesBuilder properties) {
     super.debugFillProperties(properties);
-    final List<String> listeners = <String>[];
+    final List<String> listeners = <String>[
-    if (onEnter != null) {
+      if (onEnter != null) 'enter',
-      listeners.add('enter');
+      if (onExit != null) 'exit',
-    }
+      if (onHover != null) 'hover',
-    if (onExit != null) {
+    ];
-      listeners.add('exit');
-    }
-    if (onHover != null) {
-      listeners.add('hover');
-    }
     properties.add(IterableProperty<String>('listeners', listeners, ifEmpty: '<none>'));
     properties.add(DiagnosticsProperty<MouseCursor>('cursor', cursor, defaultValue: null));
     properties.add(DiagnosticsProperty<bool>('opaque', opaque, defaultValue: true));
@@ -7573,12 +7568,10 @@ class KeyedSubtree extends StatelessWidget {
       return items;
     }
 
-    final List<Widget> itemsWithUniqueKeys = <Widget>[];
+    final List<Widget> itemsWithUniqueKeys = <Widget>[
-    int itemIndex = baseIndex;
+      for (final (int i, Widget item) in items.indexed)
-    for (final Widget item in items) {
+        KeyedSubtree.wrap(item, baseIndex + i),
-      itemsWithUniqueKeys.add(KeyedSubtree.wrap(item, itemIndex));
+    ];
-      itemIndex += 1;
-    }
 
     assert(!debugItemsHaveDuplicateKeys(itemsWithUniqueKeys));
     return itemsWithUniqueKeys;

packages/flutter/lib/src/widgets/drag_target.dart

@@ -909,17 +909,12 @@ class _DragAvatar<T extends Object> extends Drag {
   Iterable<_DragTargetState<Object>> _getDragTargets(Iterable<HitTestEntry> path) {
     // Look for the RenderBoxes that corresponds to the hit target (the hit target
     // widgets build RenderMetaData boxes for us for this purpose).
-    final List<_DragTargetState<Object>> targets = <_DragTargetState<Object>>[];
+    return <_DragTargetState<Object>>[
-    for (final HitTestEntry entry in path) {
+      for (final HitTestEntry entry in path)
-      final HitTestTarget target = entry.target;
+        if (entry.target case final RenderMetaData target)
-      if (target is RenderMetaData) {
+          if (target.metaData case final _DragTargetState<Object> metaData)
-        final dynamic metaData = target.metaData;
+            if (metaData.isExpectedDataType(data, T)) metaData,
-        if (metaData is _DragTargetState && metaData.isExpectedDataType(data, T)) {
+    ];
-          targets.add(metaData);
-        }
-      }
-    }
-    return targets;
   }
 
   void _leaveAllEntered() {

packages/flutter/lib/src/widgets/focus_manager.dart

@@ -2035,15 +2035,11 @@ class _HighlightModeManager {
     // Check to see if any of the early handlers handle the key. If so, then
     // return early.
     if (_earlyKeyEventHandlers.isNotEmpty) {
-      final List<KeyEventResult> results = <KeyEventResult>[];
+      final List<KeyEventResult> results = <KeyEventResult>[
-      // Copy the list before iteration to prevent problems if the list gets
+        // Make a copy to prevent problems if the list is modified during iteration.
-      // modified during iteration.
+        for (final OnKeyEventCallback callback in _earlyKeyEventHandlers.toList())
-      final List<OnKeyEventCallback> iterationList = _earlyKeyEventHandlers.toList();
+          for (final KeyEvent event in message.events) callback(event),
-      for (final OnKeyEventCallback callback in iterationList) {
+      ];
-        for (final KeyEvent event in message.events) {
-          results.add(callback(event));
-        }
-      }
       final KeyEventResult result = combineKeyEventResults(results);
       switch (result) {
         case KeyEventResult.ignored:
@@ -2067,15 +2063,13 @@ class _HighlightModeManager {
       FocusManager.instance.primaryFocus!,
       ...FocusManager.instance.primaryFocus!.ancestors,
     ]) {
-      final List<KeyEventResult> results = <KeyEventResult>[];
+      final List<KeyEventResult> results = <KeyEventResult>[
-      if (node.onKeyEvent != null) {
+        if (node.onKeyEvent != null)
-        for (final KeyEvent event in message.events) {
+          for (final KeyEvent event in message.events)
-          results.add(node.onKeyEvent!(node, event));
+            node.onKeyEvent!(node, event),
-        }
+        if (node.onKey != null && message.rawEvent != null)
-      }
+          node.onKey!(node, message.rawEvent!),
-      if (node.onKey != null && message.rawEvent != null) {
+      ];
-        results.add(node.onKey!(node, message.rawEvent!));
-      }
       final KeyEventResult result = combineKeyEventResults(results);
       switch (result) {
         case KeyEventResult.ignored:
@@ -2095,15 +2089,11 @@ class _HighlightModeManager {
 
     // Check to see if any late key event handlers want to handle the event.
     if (!handled && _lateKeyEventHandlers.isNotEmpty) {
-      final List<KeyEventResult> results = <KeyEventResult>[];
+      final List<KeyEventResult> results = <KeyEventResult>[
-      // Copy the list before iteration to prevent problems if the list gets
+        // Make a copy to prevent problems if the list is modified during iteration.
-      // modified during iteration.
+        for (final OnKeyEventCallback callback in _lateKeyEventHandlers.toList())
-      final List<OnKeyEventCallback> iterationList = _lateKeyEventHandlers.toList();
+          for (final KeyEvent event in message.events) callback(event),
-      for (final OnKeyEventCallback callback in iterationList) {
+      ];
-        for (final KeyEvent event in message.events) {
-          results.add(callback(event));
-        }
-      }
       final KeyEventResult result = combineKeyEventResults(results);
       switch (result) {
         case KeyEventResult.ignored:

packages/flutter/lib/src/widgets/framework.dart

@@ -3194,14 +3194,11 @@ class BuildOwner {
                   keyStringCount[key] = 1;
                 }
               }
-              final List<String> keyLabels = <String>[];
+              final List<String> keyLabels = <String>[
-              keyStringCount.forEach((String key, int count) {
+                for (final MapEntry<String, int>(:String key, value: int count) in keyStringCount.entries)
-                if (count == 1) {
+                  if (count == 1) key
-                  keyLabels.add(key);
+                  else '$key ($count different affected keys had this toString representation)',
-                } else {
+              ];
-                  keyLabels.add('$key ($count different affected keys had this toString representation)');
-                }
-              });
               final Iterable<Element> elements = _debugElementsThatWillNeedToBeRebuiltDueToGlobalKeyShenanigans!.keys;
               final Map<String, int> elementStringCount = HashMap<String, int>();
               for (final String element in elements.map<String>((Element element) => element.toString())) {
@@ -3211,14 +3208,11 @@ class BuildOwner {
                   elementStringCount[element] = 1;
                 }
               }
-              final List<String> elementLabels = <String>[];
+              final List<String> elementLabels = <String>[
-              elementStringCount.forEach((String element, int count) {
+                for (final MapEntry<String, int>(key: String element, value: int count) in elementStringCount.entries)
-                if (count == 1) {
+                  if (count == 1) element
-                  elementLabels.add(element);
+                  else '$element ($count different affected elements had this toString representation)',
-                } else {
+              ];
-                  elementLabels.add('$element ($count different affected elements had this toString representation)');
-                }
-              });
               assert(keyLabels.isNotEmpty);
               final String the = keys.length == 1 ? ' the' : '';
               final String s = keys.length == 1 ? '' : 's';

packages/flutter/lib/src/widgets/platform_menu_bar.dart

@@ -666,22 +666,12 @@ class PlatformMenuItemGroup extends PlatformMenuItem {
     PlatformMenuDelegate delegate, {
     required MenuItemSerializableIdGenerator getId,
   }) {
-    final List<Map<String, Object?>> result = <Map<String, Object?>>[];
+    return <Map<String, Object?>>[
-    result.add(<String, Object?>{
+      <String, Object?>{_kIdKey: getId(group), _kIsDividerKey: true},
-      _kIdKey: getId(group),
+      for (final PlatformMenuItem item in group.members)
-      _kIsDividerKey: true,
+        ...item.toChannelRepresentation(delegate, getId: getId),
-    });
+      <String, Object?>{_kIdKey: getId(group), _kIsDividerKey: true},
-    for (final PlatformMenuItem item in group.members) {
+    ];
-      result.addAll(item.toChannelRepresentation(
-        delegate,
-        getId: getId,
-      ));
-    }
-    result.add(<String, Object?>{
-      _kIdKey: getId(group),
-      _kIsDividerKey: true,
-    });
-    return result;
   }
 
   @override

packages/flutter/lib/src/widgets/scroll_position.dart

@@ -729,13 +729,10 @@ abstract class ScrollPosition extends ViewportOffset with ScrollMetrics {
       AxisDirection.right => (SemanticsAction.scrollLeft, SemanticsAction.scrollRight),
     };
 
-    final Set<SemanticsAction> actions = <SemanticsAction>{};
+    final Set<SemanticsAction> actions = <SemanticsAction>{
-    if (pixels > minScrollExtent) {
+      if (pixels > minScrollExtent) backward,
-      actions.add(backward);
+      if (pixels < maxScrollExtent) forward,
-    }
+    };
-    if (pixels < maxScrollExtent) {
-      actions.add(forward);
-    }
 
     if (setEquals<SemanticsAction>(actions, _semanticActions)) {
       return;

packages/flutter/lib/src/widgets/scrollable.dart

@@ -2350,23 +2350,22 @@ class _HorizontalInnerDimensionState extends ScrollableState {
     ScrollPositionAlignmentPolicy alignmentPolicy = ScrollPositionAlignmentPolicy.explicit,
     RenderObject? targetRenderObject,
   }) {
-    final List<Future<void>> newFutures = <Future<void>>[];
+    final List<Future<void>> newFutures = <Future<void>>[
-
+      position.ensureVisible(
-    newFutures.add(position.ensureVisible(
+        object,
-      object,
+        alignment: alignment,
-      alignment: alignment,
+        duration: duration,
-      duration: duration,
+        curve: curve,
-      curve: curve,
+        alignmentPolicy: alignmentPolicy,
-      alignmentPolicy: alignmentPolicy,
+      ),
-    ));
+      verticalScrollable.position.ensureVisible(
-
+        object,
-    newFutures.add(verticalScrollable.position.ensureVisible(
+        alignment: alignment,
-      object,
+        duration: duration,
-      alignment: alignment,
+        curve: curve,
-      duration: duration,
+        alignmentPolicy: alignmentPolicy,
-      curve: curve,
+      ),
-      alignmentPolicy: alignmentPolicy,
+    ];
-    ));
 
     return (newFutures, verticalScrollable);
   }

packages/flutter/lib/src/widgets/selectable_region.dart

@@ -2213,13 +2213,10 @@ abstract class MultiSelectableSelectionContainerDelegate extends SelectionContai
   /// Copies the selected contents of all [Selectable]s.
   @override
   SelectedContent? getSelectedContent() {
-    final List<SelectedContent> selections = <SelectedContent>[];
+    final List<SelectedContent> selections = <SelectedContent>[
-    for (final Selectable selectable in selectables) {
+      for (final Selectable selectable in selectables)
-      final SelectedContent? data = selectable.getSelectedContent();
+        if (selectable.getSelectedContent() case final SelectedContent data) data,
-      if (data != null) {
+    ];
-        selections.add(data);
-      }
-    }
     if (selections.isEmpty) {
       return null;
     }

packages/flutter/lib/src/widgets/tap_region.dart

@@ -254,18 +254,14 @@ class RenderTapRegionSurface extends RenderProxyBoxWithHitTestBehavior implement
     // groups of regions that were not hit.
     final Set<RenderTapRegion> hitRegions =
         _getRegionsHit(_registeredRegions, result.path).cast<RenderTapRegion>().toSet();
-    final Set<RenderTapRegion> insideRegions = <RenderTapRegion>{};
     assert(_tapRegionDebug('Tap event hit ${hitRegions.length} descendants.'));
 
-    for (final RenderTapRegion region in hitRegions) {
+    final Set<RenderTapRegion> insideRegions = <RenderTapRegion>{
-      if (region.groupId == null) {
+      for (final RenderTapRegion region in hitRegions)
-        insideRegions.add(region);
+        if (region.groupId == null) region
-        continue;
+        // Adding all grouped regions, so they act as a single region.
-      }
+        else ..._groupIdToRegions[region.groupId]!,
-      // Add all grouped regions to the insideRegions so that groups act as a
+    };
-      // single region.
-      insideRegions.addAll(_groupIdToRegions[region.groupId]!);
-    }
     // If they're not inside, then they're outside.
     final Set<RenderTapRegion> outsideRegions = _registeredRegions.difference(insideRegions);
 
@@ -292,15 +288,12 @@ class RenderTapRegionSurface extends RenderProxyBoxWithHitTestBehavior implement
   }
 
   // Returns the registered regions that are in the hit path.
-  Iterable<HitTestTarget> _getRegionsHit(Set<RenderTapRegion> detectors, Iterable<HitTestEntry> hitTestPath) {
+  Set<HitTestTarget> _getRegionsHit(Set<RenderTapRegion> detectors, Iterable<HitTestEntry> hitTestPath) {
-    final Set<HitTestTarget> hitRegions = <HitTestTarget>{};
+    return <HitTestTarget>{
-    for (final HitTestEntry<HitTestTarget> entry in hitTestPath) {
+      for (final HitTestEntry<HitTestTarget> entry in hitTestPath)
-      final HitTestTarget target = entry.target;
+        if (entry.target case final HitTestTarget target)
-      if (_registeredRegions.contains(target)) {
+          if (_registeredRegions.contains(target)) target,
-        hitRegions.add(target);
+    };
-      }
-    }
-    return hitRegions;
   }
 }
 

packages/flutter/lib/src/widgets/view.dart

@@ -699,17 +699,14 @@ class _MultiChildComponentElement extends Element {
 
   @override
   List<DiagnosticsNode> debugDescribeChildren() {
-    final List<DiagnosticsNode> children = <DiagnosticsNode>[];
+    return <DiagnosticsNode>[
-    if (_childElement != null) {
+      if (_childElement != null) _childElement!.toDiagnosticsNode(),
-      children.add(_childElement!.toDiagnosticsNode());
+      for (int i = 0; i < _viewElements.length; i++)
-    }
+        _viewElements[i].toDiagnosticsNode(
-    for (int i = 0; i < _viewElements.length; i++) {
+          name: 'view ${i + 1}',
-      children.add(_viewElements[i].toDiagnosticsNode(
+          style: DiagnosticsTreeStyle.offstage,
-        name: 'view ${i + 1}',
+        ),
-        style: DiagnosticsTreeStyle.offstage,
+    ];
-      ));
-    }
-    return children;
   }
 }
 

packages/flutter/lib/src/widgets/widget_inspector.dart

@@ -960,17 +960,11 @@ mixin WidgetInspectorService {
     registerServiceExtension(
       name: name,
       callback: (Map<String, String> parameters) async {
-        final List<String> args = <String>[];
+        int index;
-        int index = 0;
+        final List<String> args = <String>[
-        while (true) {
+          for (index = 0; parameters['arg$index'] != null; index++)
-          final String name = 'arg$index';
+            parameters['arg$index']!,
-          if (parameters.containsKey(name)) {
+        ];
-            args.add(parameters[name]!);
-          } else {
-            break;
-          }
-          index++;
-        }
         // Verify that the only arguments other than perhaps 'isolateId' are
         // arguments we have already handled.
         assert(index == parameters.length || (index == parameters.length - 1 && parameters.containsKey('isolateId')));
@@ -3408,27 +3402,16 @@ class _Location {
   final String? name;
 
   Map<String, Object?> toJsonMap() {
-    final Map<String, Object?> json = <String, Object?>{
+    return <String, Object?>{
       'file': file,
       'line': line,
       'column': column,
+      if (name != null) 'name': name,
     };
-    if (name != null) {
-      json['name'] = name;
-    }
-    return json;
   }
 
   @override
-  String toString() {
+  String toString() => <String>[if (name != null) name!, file, '$line', '$column'].join(':');
-    final List<String> parts = <String>[];
-    if (name != null) {
-      parts.add(name!);
-    }
-    parts.add(file);
-    parts..add('$line')..add('$column');
-    return parts.join(':');
-  }
 }
 
 bool _isDebugCreator(DiagnosticsNode node) => node is DiagnosticsDebugCreator;

packages/flutter/test/cupertino/text_selection_toolbar_test.dart

@@ -204,12 +204,7 @@ void main() {
 
     // Adding 7 more children overflows onto a third page.
     setState(() {
-      children.add(const TestBox());
+      children.addAll(List<TestBox>.filled(6, const TestBox()));
-      children.add(const TestBox());
-      children.add(const TestBox());
-      children.add(const TestBox());
-      children.add(const TestBox());
-      children.add(const TestBox());
     });
     await tester.pumpAndSettle();
     expect(find.byType(TestBox), findsNWidgets(7));

packages/flutter/test/material/spell_check_suggestions_toolbar_test.dart

@@ -17,24 +17,15 @@ void main() {
 
   /// Builds test button items for each of the suggestions provided.
   List<ContextMenuButtonItem> buildSuggestionButtons(List<String> suggestions) {
-    final List<ContextMenuButtonItem> buttonItems = <ContextMenuButtonItem>[];
+    return <ContextMenuButtonItem>[
-
+      for (final String suggestion in suggestions)
-    for (final String suggestion in suggestions) {
+        ContextMenuButtonItem(onPressed: () {}, label: suggestion),
-      buttonItems.add(ContextMenuButtonItem(
-        onPressed: () {},
-        label: suggestion,
-      ));
-    }
-
-    final ContextMenuButtonItem deleteButton =
       ContextMenuButtonItem(
         onPressed: () {},
         type: ContextMenuButtonType.delete,
         label: 'DELETE',
-    );
+      ),
-    buttonItems.add(deleteButton);
+    ];
-
-    return buttonItems;
   }
 
   /// Finds the container of the [SpellCheckSuggestionsToolbar] so that

packages/flutter/test/widgets/slivers_test.dart

@@ -338,14 +338,10 @@ void main() {
   testWidgets('SliverFixedExtentList handles underflow when its children changes', (WidgetTester tester) async {
     final List<String> items = <String>['1', '2', '3', '4', '5', '6'];
     final List<String> initializedChild = <String>[];
-    List<Widget> children = <Widget>[];
+    List<Widget> children = <Widget>[
-    for (final String item in items) {
+      for (final String item in items)
-      children.add(
+        StateInitSpy(item, () => initializedChild.add(item), key: ValueKey<String>(item)),
-          StateInitSpy(
+    ];
-            item, () => initializedChild.add(item), key: ValueKey<String>(item),
-          ),
-      );
-    }
     final ScrollController controller = ScrollController(initialScrollOffset: 5400);
     addTearDown(controller.dispose);
 

packages/integration_test/lib/common.dart

@@ -106,16 +106,10 @@ class Response {
 
   /// Create a list of Strings from [_failureDetails].
   List<String> _failureDetailsAsString() {
-    final List<String> list = <String>[];
+    return <String>[
-    if (_failureDetails == null || _failureDetails.isEmpty) {
+      if (_failureDetails != null)
-      return list;
+        for (final Failure failure in _failureDetails) failure.toJson(),
-    }
+    ];
-
-    for (final Failure failure in _failureDetails) {
-      list.add(failure.toJson());
-    }
-
-    return list;
   }
 
   /// Creates a [Failure] list using a json response.