diff --git a/analysis_options.yaml b/analysis_options.yaml
index 9d9836c3b2..f2de0956aa 100644
--- a/analysis_options.yaml
+++ b/analysis_options.yaml
@@ -123,6 +123,7 @@ linter:
     # - no_logic_in_create_state # not yet tested
     # - no_runtimeType_toString # not yet tested
     - non_constant_identifier_names
+    - null_check_on_nullable_type_parameter
     # - null_closures  # not yet tested
     # - omit_local_variable_types # opposite of always_specify_types
     # - one_member_abstracts # too many false positives
@@ -180,6 +181,7 @@ linter:
     - sort_unnamed_constructors_first
     - test_types_in_equals
     - throw_in_finally
+    - tighten_type_of_initializing_formals
     # - type_annotate_public_apis # subset of always_specify_types
     - type_init_formals
     # - unawaited_futures # too many false positives
diff --git a/packages/flutter/lib/src/animation/animations.dart b/packages/flutter/lib/src/animation/animations.dart
index eb4aae3577..1858033976 100644
--- a/packages/flutter/lib/src/animation/animations.dart
+++ b/packages/flutter/lib/src/animation/animations.dart
@@ -491,8 +491,11 @@ class TrainHoppingAnimation extends Animation<double>
   /// The current train argument must not be null but the next train argument
   /// can be null. If the next train is null, then this object will just proxy
   /// the first animation and never hop.
-  TrainHoppingAnimation(this._currentTrain, this._nextTrain, { this.onSwitchedTrain })
-      : assert(_currentTrain != null) {
+  TrainHoppingAnimation(
+    Animation<double> this._currentTrain,
+    this._nextTrain, {
+    this.onSwitchedTrain,
+  }) : assert(_currentTrain != null) {
     if (_nextTrain != null) {
       if (_currentTrain!.value == _nextTrain!.value) {
         _currentTrain = _nextTrain;
diff --git a/packages/flutter/lib/src/material/app.dart b/packages/flutter/lib/src/material/app.dart
index 874de23ea0..ad2dae6aeb 100644
--- a/packages/flutter/lib/src/material/app.dart
+++ b/packages/flutter/lib/src/material/app.dart
@@ -169,12 +169,12 @@ class MaterialApp extends StatefulWidget {
     this.navigatorKey,
     this.scaffoldMessengerKey,
     this.home,
-    this.routes = const <String, WidgetBuilder>{},
+    Map<String, WidgetBuilder> this.routes = const <String, WidgetBuilder>{},
     this.initialRoute,
     this.onGenerateRoute,
     this.onGenerateInitialRoutes,
     this.onUnknownRoute,
-    this.navigatorObservers = const <NavigatorObserver>[],
+    List<NavigatorObserver> this.navigatorObservers = const <NavigatorObserver>[],
     this.builder,
     this.title = '',
     this.onGenerateTitle,
@@ -218,8 +218,8 @@ class MaterialApp extends StatefulWidget {
     Key? key,
     this.scaffoldMessengerKey,
     this.routeInformationProvider,
-    required this.routeInformationParser,
-    required this.routerDelegate,
+    required RouteInformationParser<Object> this.routeInformationParser,
+    required RouterDelegate<Object> this.routerDelegate,
     this.backButtonDispatcher,
     this.builder,
     this.title = '',
diff --git a/packages/flutter/lib/src/material/input_decorator.dart b/packages/flutter/lib/src/material/input_decorator.dart
index 524e69dfff..28d30142ce 100644
--- a/packages/flutter/lib/src/material/input_decorator.dart
+++ b/packages/flutter/lib/src/material/input_decorator.dart
@@ -3736,7 +3736,7 @@ class InputDecorationTheme with Diagnosticable {
   /// true and bordered per the [border].
   ///
   /// This property is false by default.
-  final bool? filled;
+  final bool filled;
 
   /// The color to fill the decoration's container with, if [filled] is true.
   ///
diff --git a/packages/flutter/lib/src/material/pickers/input_date_picker.dart b/packages/flutter/lib/src/material/pickers/input_date_picker.dart
index c2172da49b..b3345b2d69 100644
--- a/packages/flutter/lib/src/material/pickers/input_date_picker.dart
+++ b/packages/flutter/lib/src/material/pickers/input_date_picker.dart
@@ -224,7 +224,7 @@ class _InputDatePickerFormFieldState extends State<InputDatePickerFormField> {
     return TextFormField(
       decoration: InputDecoration(
         border: inputTheme.border ?? const UnderlineInputBorder(),
-        filled: inputTheme.filled ?? true,
+        filled: inputTheme.filled,
         hintText: widget.fieldHintText ?? localizations.dateHelpText,
         labelText: widget.fieldLabelText ?? localizations.dateInputLabel,
       ),
diff --git a/packages/flutter/lib/src/material/pickers/input_date_range_picker.dart b/packages/flutter/lib/src/material/pickers/input_date_range_picker.dart
index 9b161b3d0b..bd11184105 100644
--- a/packages/flutter/lib/src/material/pickers/input_date_range_picker.dart
+++ b/packages/flutter/lib/src/material/pickers/input_date_range_picker.dart
@@ -235,7 +235,7 @@ class InputDateRangePickerState extends State<InputDateRangePicker> {
             controller: _startController,
             decoration: InputDecoration(
               border: inputTheme.border ?? const UnderlineInputBorder(),
-              filled: inputTheme.filled ?? true,
+              filled: inputTheme.filled,
               hintText: widget.fieldStartHintText ?? localizations.dateHelpText,
               labelText: widget.fieldStartLabelText ?? localizations.dateRangeStartLabel,
               errorText: _startErrorText,
@@ -251,7 +251,7 @@ class InputDateRangePickerState extends State<InputDateRangePicker> {
             controller: _endController,
             decoration: InputDecoration(
               border: inputTheme.border ?? const UnderlineInputBorder(),
-              filled: inputTheme.filled ?? true,
+              filled: inputTheme.filled,
               hintText: widget.fieldEndHintText ?? localizations.dateHelpText,
               labelText: widget.fieldEndLabelText ?? localizations.dateRangeEndLabel,
               errorText: _endErrorText,
diff --git a/packages/flutter/lib/src/material/selectable_text.dart b/packages/flutter/lib/src/material/selectable_text.dart
index ab76518bdb..c4b348346f 100644
--- a/packages/flutter/lib/src/material/selectable_text.dart
+++ b/packages/flutter/lib/src/material/selectable_text.dart
@@ -174,7 +174,7 @@ class SelectableText extends StatefulWidget {
   /// must not be null. If specified, the [maxLines] argument must be greater
   /// than zero.
   const SelectableText(
-    this.data, {
+    String this.data, {
     Key? key,
     this.focusNode,
     this.style,
@@ -226,7 +226,7 @@ class SelectableText extends StatefulWidget {
   ///
   /// The [autofocus] and [dragStartBehavior] arguments must not be null.
   const SelectableText.rich(
-    this.textSpan, {
+    TextSpan this.textSpan, {
     Key? key,
     this.focusNode,
     this.style,
diff --git a/packages/flutter/lib/src/rendering/mouse_tracking.dart b/packages/flutter/lib/src/rendering/mouse_tracking.dart
index 9de866e424..bdd90f8fbd 100644
--- a/packages/flutter/lib/src/rendering/mouse_tracking.dart
+++ b/packages/flutter/lib/src/rendering/mouse_tracking.dart
@@ -177,7 +177,7 @@ class MouseTrackerUpdateDetails with Diagnosticable {
   const MouseTrackerUpdateDetails.byNewFrame({
     required this.lastAnnotations,
     required this.nextAnnotations,
-    required this.previousEvent,
+    required PointerEvent this.previousEvent,
   }) : assert(previousEvent != null),
        assert(lastAnnotations != null),
        assert(nextAnnotations != null),
diff --git a/packages/flutter/lib/src/widgets/async.dart b/packages/flutter/lib/src/widgets/async.dart
index 9a4d26ed1a..b78acbd1b4 100644
--- a/packages/flutter/lib/src/widgets/async.dart
+++ b/packages/flutter/lib/src/widgets/async.dart
@@ -500,7 +500,7 @@ class StreamBuilder<T> extends StreamBuilderBase<T, AsyncSnapshot<T>> {
   @override
   AsyncSnapshot<T> initial() => initialData == null
       ? AsyncSnapshot<T>.nothing()
-      : AsyncSnapshot<T>.withData(ConnectionState.none, initialData!);
+      : AsyncSnapshot<T>.withData(ConnectionState.none, initialData as T);
 
   @override
   AsyncSnapshot<T> afterConnected(AsyncSnapshot<T> current) => current.inState(ConnectionState.waiting);
@@ -733,7 +733,7 @@ class _FutureBuilderState<T> extends State<FutureBuilder<T>> {
     super.initState();
     _snapshot = widget.initialData == null
         ? AsyncSnapshot<T>.nothing()
-        : AsyncSnapshot<T>.withData(ConnectionState.none, widget.initialData!);
+        : AsyncSnapshot<T>.withData(ConnectionState.none, widget.initialData as T);
     _subscribe();
   }
 
diff --git a/packages/flutter/lib/src/widgets/disposable_build_context.dart b/packages/flutter/lib/src/widgets/disposable_build_context.dart
index 213067cd83..3a049ed75c 100644
--- a/packages/flutter/lib/src/widgets/disposable_build_context.dart
+++ b/packages/flutter/lib/src/widgets/disposable_build_context.dart
@@ -27,9 +27,9 @@ class DisposableBuildContext<T extends State> {
   /// Creators must call [dispose] when the [State] is disposed.
   ///
   /// The [State] must not be null, and [State.mounted] must be true.
-  DisposableBuildContext(this._state)
+  DisposableBuildContext(T this._state)
       : assert(_state != null),
-        assert(_state!.mounted, 'A DisposableBuildContext was given a BuildContext for an Element that is not mounted.');
+        assert(_state.mounted, 'A DisposableBuildContext was given a BuildContext for an Element that is not mounted.');
 
   T? _state;
 
diff --git a/packages/flutter/lib/src/widgets/primary_scroll_controller.dart b/packages/flutter/lib/src/widgets/primary_scroll_controller.dart
index 013f214aed..cb71d9eb9f 100644
--- a/packages/flutter/lib/src/widgets/primary_scroll_controller.dart
+++ b/packages/flutter/lib/src/widgets/primary_scroll_controller.dart
@@ -20,7 +20,7 @@ class PrimaryScrollController extends InheritedWidget {
   /// Creates a widget that associates a [ScrollController] with a subtree.
   const PrimaryScrollController({
     Key? key,
-    required this.controller,
+    required ScrollController this.controller,
     required Widget child,
   }) : assert(controller != null),
        super(key: key, child: child);