Remove unnecessary null checks in flutter/cupertino (flutter#119020)

Author: goderbauer

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

@@ -36,9 +36,7 @@ class CupertinoActivityIndicator extends StatefulWidget {
     this.color,
     this.animating = true,
     this.radius = _kDefaultIndicatorRadius,
-  })  : assert(animating != null),
-        assert(radius != null),
-        assert(radius > 0.0),
+  })  : assert(radius > 0.0),
         progress = 1.0;
 
   /// Creates a non-animated iOS-style activity indicator that displays
@@ -52,9 +50,7 @@ class CupertinoActivityIndicator extends StatefulWidget {
     this.color,
     this.radius = _kDefaultIndicatorRadius,
     this.progress = 1.0,
-  })  : assert(radius != null),
-        assert(radius > 0.0),
-        assert(progress != null),
+  })  : assert(radius > 0.0),
         assert(progress >= 0.0),
         assert(progress <= 1.0),
         animating = false;

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

@@ -177,15 +177,7 @@ class CupertinoApp extends StatefulWidget {
     this.restorationScopeId,
     this.scrollBehavior,
     this.useInheritedMediaQuery = false,
-  }) : assert(routes != null),
-       assert(navigatorObservers != null),
-       assert(title != null),
-       assert(showPerformanceOverlay != null),
-       assert(checkerboardRasterCacheImages != null),
-       assert(checkerboardOffscreenLayers != null),
-       assert(showSemanticsDebugger != null),
-       assert(debugShowCheckedModeBanner != null),
-       routeInformationProvider = null,
+  }) : routeInformationProvider = null,
        routeInformationParser = null,
        routerDelegate = null,
        backButtonDispatcher = null,
@@ -222,12 +214,6 @@ class CupertinoApp extends StatefulWidget {
     this.scrollBehavior,
     this.useInheritedMediaQuery = false,
   }) : assert(routerDelegate != null || routerConfig != null),
-       assert(title != null),
-       assert(showPerformanceOverlay != null),
-       assert(checkerboardRasterCacheImages != null),
-       assert(checkerboardOffscreenLayers != null),
-       assert(showSemanticsDebugger != null),
-       assert(debugShowCheckedModeBanner != null),
        navigatorObservers = null,
        navigatorKey = null,
        onGenerateRoute = null,

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

@@ -74,16 +74,12 @@ class CupertinoTabBar extends StatelessWidget implements PreferredSizeWidget {
         width: 0.0, // 0.0 means one physical pixel
       ),
     ),
-  }) : assert(items != null),
-       assert(
+  }) : assert(
          items.length >= 2,
          "Tabs need at least 2 items to conform to Apple's HIG",
        ),
-       assert(currentIndex != null),
        assert(0 <= currentIndex && currentIndex < items.length),
-       assert(iconSize != null),
-       assert(height != null && height >= 0.0),
-       assert(inactiveColor != null);
+       assert(height >= 0.0);
 
   /// The interactive items laid out within the bottom navigation bar.
   ///

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

@@ -50,8 +50,6 @@ class CupertinoButton extends StatefulWidget {
     this.alignment = Alignment.center,
     required this.onPressed,
   }) : assert(pressedOpacity == null || (pressedOpacity >= 0.0 && pressedOpacity <= 1.0)),
-       assert(disabledColor != null),
-       assert(alignment != null),
        _filled = false;
 
   /// Creates an iOS-style button with a filled background.
@@ -71,8 +69,6 @@ class CupertinoButton extends StatefulWidget {
     this.alignment = Alignment.center,
     required this.onPressed,
   }) : assert(pressedOpacity == null || (pressedOpacity >= 0.0 && pressedOpacity <= 1.0)),
-       assert(disabledColor != null),
-       assert(alignment != null),
        color = null,
        _filled = true;
 

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

@@ -780,16 +780,7 @@ class CupertinoDynamicColor extends Color with Diagnosticable {
     this.darkHighContrastElevatedColor,
     this._debugResolveContext,
     this._debugLabel,
-  ) : assert(color != null),
-      assert(darkColor != null),
-      assert(highContrastColor != null),
-      assert(darkHighContrastColor != null),
-      assert(elevatedColor != null),
-      assert(darkElevatedColor != null),
-      assert(highContrastElevatedColor != null),
-      assert(darkHighContrastElevatedColor != null),
-      assert(_effectiveColor != null),
-      // The super constructor has to be called with a dummy value in order to mark
+  ) : // The super constructor has to be called with a dummy value in order to mark
       // this constructor const.
       // The field `value` is overridden in the class implementation.
       super(0);
@@ -908,7 +899,6 @@ class CupertinoDynamicColor extends Color with Diagnosticable {
   ///  * [maybeResolve], which is similar to this function, but will allow a
   ///    null `resolvable` color.
   static Color resolve(Color resolvable, BuildContext context) {
-    assert(context != null);
     return (resolvable is CupertinoDynamicColor)
       ? resolvable.resolveFrom(context)
       : resolvable;
@@ -931,7 +921,6 @@ class CupertinoDynamicColor extends Color with Diagnosticable {
     if (resolvable == null) {
       return null;
     }
-    assert(context != null);
     return (resolvable is CupertinoDynamicColor)
       ? resolvable.resolveFrom(context)
       : resolvable;

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

@@ -142,8 +142,7 @@ class CupertinoContextMenu extends StatefulWidget {
       'This feature was deprecated after v3.4.0-34.1.pre.',
     )
     this.previewBuilder = _defaultPreviewBuilder,
-  }) : assert(actions != null && actions.isNotEmpty),
-       assert(child != null),
+  }) : assert(actions.isNotEmpty),
        builder = ((BuildContext context, Animation<double> animation) => child);
 
   /// Creates a context menu with a custom [builder] controlling the widget.
@@ -158,7 +157,7 @@ class CupertinoContextMenu extends StatefulWidget {
     super.key,
     required this.actions,
     required this.builder,
-  }) : assert(actions != null && actions.isNotEmpty),
+  }) : assert(actions.isNotEmpty),
        child = null,
        previewBuilder = null;
 
@@ -794,8 +793,7 @@ class _ContextMenuRoute<T> extends PopupRoute<T> {
     super.filter,
     required Rect previousChildRect,
     super.settings,
-  }) : assert(actions != null && actions.isNotEmpty),
-       assert(contextMenuLocation != null),
+  }) : assert(actions.isNotEmpty),
        _actions = actions,
        _builder = builder,
        _contextMenuLocation = contextMenuLocation,
@@ -1081,8 +1079,7 @@ class _ContextMenuRouteStatic extends StatefulWidget {
     this.onDismiss,
     required this.orientation,
     this.sheetGlobalKey,
-  }) : assert(contextMenuLocation != null),
-       assert(orientation != null);
+  });
 
   final List<Widget>? actions;
   final Widget child;
@@ -1409,9 +1406,7 @@ class _ContextMenuSheet extends StatelessWidget {
     required this.actions,
     required _ContextMenuLocation contextMenuLocation,
     required Orientation orientation,
-  }) : assert(actions != null && actions.isNotEmpty),
-       assert(contextMenuLocation != null),
-       assert(orientation != null),
+  }) : assert(actions.isNotEmpty),
        _contextMenuLocation = contextMenuLocation,
        _orientation = orientation;
 

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

@@ -20,9 +20,7 @@ class CupertinoContextMenuAction extends StatefulWidget {
     this.isDestructiveAction = false,
     this.onPressed,
     this.trailingIcon,
-  }) : assert(child != null),
-       assert(isDefaultAction != null),
-       assert(isDestructiveAction != null);
+  });
 
   /// The widget that will be placed inside the action.
   final Widget child;

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

@@ -81,8 +81,7 @@ class _DatePickerLayoutDelegate extends MultiChildLayoutDelegate {
   _DatePickerLayoutDelegate({
     required this.columnWidths,
     required this.textDirectionFactor,
-  }) : assert(columnWidths != null),
-       assert(textDirectionFactor != null);
+  });
 
   // The list containing widths of all columns.
   final List<double> columnWidths;
@@ -277,14 +276,10 @@ class CupertinoDatePicker extends StatefulWidget {
     this.dateOrder,
     this.backgroundColor,
   }) : initialDateTime = initialDateTime ?? DateTime.now(),
-       assert(mode != null),
-       assert(onDateTimeChanged != null),
-       assert(minimumYear != null),
        assert(
          minuteInterval > 0 && 60 % minuteInterval == 0,
          'minute interval is not a positive integer factor of 60',
        ) {
-    assert(this.initialDateTime != null);
     assert(
       mode != CupertinoDatePickerMode.dateAndTime || minimumDate == null || !this.initialDateTime.isBefore(minimumDate!),
       'initial date is before minimum date',
@@ -944,7 +939,6 @@ class _CupertinoDatePickerDateTimeState extends State<CupertinoDatePicker> {
   }
 
   void _scrollToDate(DateTime newDate, DateTime fromDate, bool minCheck) {
-    assert(newDate != null);
     SchedulerBinding.instance.addPostFrameCallback((Duration timestamp) {
       if (fromDate.year != newDate.year || fromDate.month != newDate.month || fromDate.day != newDate.day) {
         _animateColumnControllerToItem(dateController, selectedDayFromInitial);
@@ -1349,7 +1343,6 @@ class _CupertinoDatePickerDateState extends State<CupertinoDatePicker> {
   }
 
   void _scrollToDate(DateTime newDate) {
-    assert(newDate != null);
     SchedulerBinding.instance.addPostFrameCallback((Duration timestamp) {
       if (selectedYear != newDate.year) {
         _animateColumnControllerToItem(yearController, newDate.year);
@@ -1551,15 +1544,12 @@ class CupertinoTimerPicker extends StatefulWidget {
     this.alignment = Alignment.center,
     this.backgroundColor,
     required this.onTimerDurationChanged,
-  }) : assert(mode != null),
-       assert(onTimerDurationChanged != null),
-       assert(initialTimerDuration >= Duration.zero),
+  }) : assert(initialTimerDuration >= Duration.zero),
        assert(initialTimerDuration < const Duration(days: 1)),
        assert(minuteInterval > 0 && 60 % minuteInterval == 0),
        assert(secondInterval > 0 && 60 % secondInterval == 0),
        assert(initialTimerDuration.inMinutes % minuteInterval == 0),
-       assert(initialTimerDuration.inSeconds % secondInterval == 0),
-       assert(alignment != null);
+       assert(initialTimerDuration.inSeconds % secondInterval == 0);
 
   /// The mode of the timer picker.
   final CupertinoTimerPickerMode mode;

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

@@ -37,8 +37,7 @@ class CupertinoDesktopTextSelectionToolbarButton extends StatefulWidget {
     super.key,
     required this.onPressed,
     required Widget this.child,
-  }) : assert(child != null),
-       buttonItem = null;
+  }) : buttonItem = null;
 
   /// Create an instance of [CupertinoDesktopTextSelectionToolbarButton] whose child is
   /// a [Text] widget styled like the default Mac context menu button.
@@ -66,8 +65,7 @@ class CupertinoDesktopTextSelectionToolbarButton extends StatefulWidget {
   CupertinoDesktopTextSelectionToolbarButton.buttonItem({
     super.key,
     required ContextMenuButtonItem this.buttonItem,
-  }) : assert(buttonItem != null),
-       onPressed = buttonItem.onPressed,
+  }) : onPressed = buttonItem.onPressed,
        child = null;
 
   /// {@macro flutter.cupertino.CupertinoTextSelectionToolbarButton.onPressed}

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

@@ -201,7 +201,7 @@ class CupertinoAlertDialog extends StatelessWidget {
     this.actionScrollController,
     this.insetAnimationDuration = const Duration(milliseconds: 100),
     this.insetAnimationCurve = Curves.decelerate,
-  }) : assert(actions != null);
+  });
 
   /// The (optional) title of the dialog is displayed in a large font at the top
   /// of the dialog.
@@ -665,8 +665,7 @@ class CupertinoActionSheetAction extends StatelessWidget {
     this.isDefaultAction = false,
     this.isDestructiveAction = false,
     required this.child,
-  }) : assert(child != null),
-       assert(onPressed != null);
+  });
 
   /// The callback that is called when the button is tapped.
   ///
@@ -701,7 +700,7 @@ class CupertinoActionSheetAction extends StatelessWidget {
     }
 
     return MouseRegion(
-      cursor: onPressed != null && kIsWeb ? SystemMouseCursors.click : MouseCursor.defer,
+      cursor: kIsWeb ? SystemMouseCursors.click : MouseCursor.defer,
       child: GestureDetector(
         onTap: onPressed,
         behavior: HitTestBehavior.opaque,
@@ -896,7 +895,6 @@ class _CupertinoDialogRenderElement extends RenderObjectElement {
   }
 
   void _placeChildInSlot(RenderObject child, _AlertDialogSections slot) {
-    assert(slot != null);
     switch (slot) {
       case _AlertDialogSections.contentSection:
         renderObject.contentSection = child as RenderBox;
@@ -1443,7 +1441,7 @@ class _CupertinoAlertActionSection extends StatelessWidget {
     this.scrollController,
     this.hasCancelButton = false,
     this.isActionSheet = false,
-  }) : assert(children != null);
+  });
 
   final List<Widget> children;
 
@@ -1593,9 +1591,7 @@ class CupertinoDialogAction extends StatelessWidget {
     this.isDestructiveAction = false,
     this.textStyle,
     required this.child,
-  }) : assert(child != null),
-       assert(isDefaultAction != null),
-       assert(isDestructiveAction != null);
+  });
 
   /// The callback that is called when the button is tapped or otherwise
   /// activated.