Make constraints a covariant argument in RenderBox.computeDryLayout() (#136432)

Some render box subclasses have a specific layout contract that is tightly coupled with other render box subclasses (e.g. two private classes in a local project file). In these cases, it is also possible that they use a constraints object that is a subclass of `BoxConstraints`. To allow for this, this change makes the `constraints` argument to `RenderBox.computeDryLayout()` a covariant argument.

For completeness' sake, this updates the other render objects in the rendering package to also use the covariant keyword for this argument.

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

@@ -264,7 +264,8 @@ class RenderAnimatedSize extends RenderAligningShiftedBox {
   }
 
   @override
-  Size computeDryLayout(BoxConstraints constraints) {
+  @protected
+  Size computeDryLayout(covariant BoxConstraints constraints) {
     if (child == null || constraints.isTight) {
       return constraints.smallest;
     }

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

@@ -1906,7 +1906,7 @@ abstract class RenderBox extends RenderObject {
   /// [debugCannotComputeDryLayout] from within an assert and return a dummy
   /// value of `const Size(0, 0)`.
   @protected
-  Size computeDryLayout(BoxConstraints constraints) {
+  Size computeDryLayout(covariant BoxConstraints constraints) {
     assert(debugCannotComputeDryLayout(
       error: FlutterError.fromParts(<DiagnosticsNode>[
         ErrorSummary('The ${objectRuntimeType(this, 'RenderBox')} class does not implement "computeDryLayout".'),

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

@@ -393,7 +393,8 @@ class RenderCustomMultiChildLayoutBox extends RenderBox
   }
 
   @override
-  Size computeDryLayout(BoxConstraints constraints) {
+  @protected
+  Size computeDryLayout(covariant BoxConstraints constraints) {
     return _getSize(constraints);
   }
 

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

@@ -2270,7 +2270,8 @@ class RenderEditable extends RenderBox with RelayoutWhenSystemFontsChangeMixin,
   bool get _canComputeIntrinsics => _canComputeIntrinsicsCached ??= _canComputeDryLayoutForInlineWidgets();
 
   @override
-  Size computeDryLayout(BoxConstraints constraints) {
+  @protected
+  Size computeDryLayout(covariant BoxConstraints constraints) {
     if (!_canComputeIntrinsics) {
       assert(debugCannotComputeDryLayout(
         reason: 'Dry layout not available for alignments that require baseline.',
@@ -2630,7 +2631,8 @@ class _RenderEditableCustomPaint extends RenderBox {
   }
 
   @override
-  Size computeDryLayout(BoxConstraints constraints) => constraints.biggest;
+  @protected
+  Size computeDryLayout(covariant BoxConstraints constraints) => constraints.biggest;
 }
 
 /// An interface that paints within a [RenderEditable]'s bounds, above or

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

@@ -4,6 +4,8 @@
 
 import 'dart:ui' as ui show Paragraph, ParagraphBuilder, ParagraphConstraints, ParagraphStyle, TextStyle;
 
+import 'package:flutter/foundation.dart';
+
 import 'box.dart';
 import 'object.dart';
 
@@ -77,7 +79,8 @@ class RenderErrorBox extends RenderBox {
   bool hitTestSelf(Offset position) => true;
 
   @override
-  Size computeDryLayout(BoxConstraints constraints) {
+  @protected
+  Size computeDryLayout(covariant BoxConstraints constraints) {
     return constraints.constrain(const Size(_kMaxWidth, _kMaxHeight));
   }
 

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

@@ -653,7 +653,8 @@ class RenderFlex extends RenderBox with ContainerRenderObjectMixin<RenderBox, Fl
   }
 
   @override
-  Size computeDryLayout(BoxConstraints constraints) {
+  @protected
+  Size computeDryLayout(covariant BoxConstraints constraints) {
     if (!_canComputeIntrinsics) {
       assert(debugCannotComputeDryLayout(
         reason: 'Dry layout cannot be computed for CrossAxisAlignment.baseline, which requires a full layout.',

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

@@ -299,7 +299,8 @@ class RenderFlow extends RenderBox
   }
 
   @override
-  Size computeDryLayout(BoxConstraints constraints) {
+  @protected
+  Size computeDryLayout(covariant BoxConstraints constraints) {
     return _getSize(constraints);
   }
 

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

@@ -5,6 +5,7 @@
 import 'dart:ui' as ui show Image;
 
 import 'package:flutter/animation.dart';
+import 'package:flutter/foundation.dart';
 
 import 'box.dart';
 import 'object.dart';
@@ -401,7 +402,8 @@ class RenderImage extends RenderBox {
   bool hitTestSelf(Offset position) => true;
 
   @override
-  Size computeDryLayout(BoxConstraints constraints) {
+  @protected
+  Size computeDryLayout(covariant BoxConstraints constraints) {
     return _sizeForConstraints(constraints);
   }
 

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

@@ -4,6 +4,8 @@
 
 import 'dart:math' as math;
 
+import 'package:flutter/foundation.dart';
+
 import 'box.dart';
 import 'object.dart';
 
@@ -62,7 +64,8 @@ class RenderListBody extends RenderBox
   Axis get mainAxis => axisDirectionToAxis(axisDirection);
 
   @override
-  Size computeDryLayout(BoxConstraints constraints) {
+  @protected
+  Size computeDryLayout(covariant BoxConstraints constraints) {
     assert(_debugCheckConstraints(constraints));
     double mainAxisExtent = 0.0;
     RenderBox? child = firstChild;

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

@@ -5,6 +5,7 @@
 import 'dart:math' as math;
 
 import 'package:flutter/animation.dart';
+import 'package:flutter/foundation.dart';
 import 'package:vector_math/vector_math_64.dart' show Matrix4;
 
 import 'box.dart';
@@ -615,7 +616,8 @@ class RenderListWheelViewport
   bool get sizedByParent => true;
 
   @override
-  Size computeDryLayout(BoxConstraints constraints) {
+  @protected
+  Size computeDryLayout(covariant BoxConstraints constraints) {
     return constraints.biggest;
   }
 

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

@@ -772,7 +772,8 @@ class RenderParagraph extends RenderBox with ContainerRenderObjectMixin<RenderBo
   }
 
   @override
-  Size computeDryLayout(BoxConstraints constraints) {
+  @protected
+  Size computeDryLayout(covariant BoxConstraints constraints) {
     if (!_canComputeIntrinsics()) {
       assert(debugCannotComputeDryLayout(
         reason: 'Dry layout not available for alignments that require baseline.',

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

@@ -2,6 +2,8 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
+import 'package:flutter/foundation.dart';
+
 import 'box.dart';
 import 'layer.dart';
 import 'object.dart';
@@ -157,7 +159,8 @@ class RenderPerformanceOverlay extends RenderBox {
   }
 
   @override
-  Size computeDryLayout(BoxConstraints constraints) {
+  @protected
+  Size computeDryLayout(covariant BoxConstraints constraints) {
     return constraints.constrain(Size(double.infinity, _intrinsicHeight));
   }
 

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

@@ -148,7 +148,8 @@ class RenderAndroidView extends PlatformViewRenderBox {
   bool get isRepaintBoundary => true;
 
   @override
-  Size computeDryLayout(BoxConstraints constraints) {
+  @protected
+  Size computeDryLayout(covariant BoxConstraints constraints) {
     return constraints.biggest;
   }
 
@@ -319,7 +320,8 @@ abstract class RenderDarwinPlatformView<T extends DarwinPlatformViewController>
   _UiKitViewGestureRecognizer? _gestureRecognizer;
 
   @override
-  Size computeDryLayout(BoxConstraints constraints) {
+  @protected
+  Size computeDryLayout(covariant BoxConstraints constraints) {
     return constraints.biggest;
   }
 
@@ -711,7 +713,8 @@ class PlatformViewRenderBox extends RenderBox with _PlatformViewGestureMixin {
   bool get isRepaintBoundary => true;
 
   @override
-  Size computeDryLayout(BoxConstraints constraints) {
+  @protected
+  Size computeDryLayout(covariant BoxConstraints constraints) {
     return constraints.biggest;
   }
 

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

@@ -95,7 +95,8 @@ mixin RenderProxyBoxMixin<T extends RenderBox> on RenderBox, RenderObjectWithChi
   }
 
   @override
-  Size computeDryLayout(BoxConstraints constraints) {
+  @protected
+  Size computeDryLayout(covariant BoxConstraints constraints) {
     return child?.getDryLayout(constraints) ?? computeSizeForNoChild(constraints);
   }
 
@@ -284,7 +285,8 @@ class RenderConstrainedBox extends RenderProxyBox {
   }
 
   @override
-  Size computeDryLayout(BoxConstraints constraints) {
+  @protected
+  Size computeDryLayout(covariant BoxConstraints constraints) {
     if (child != null) {
       return child!.getDryLayout(_additionalConstraints.enforce(constraints));
     } else {
@@ -383,7 +385,8 @@ class RenderLimitedBox extends RenderProxyBox {
   }
 
   @override
-  Size computeDryLayout(BoxConstraints constraints) {
+  @protected
+  Size computeDryLayout(covariant BoxConstraints constraints) {
     return _computeSize(
       constraints: constraints,
       layoutChild: ChildLayoutHelper.dryLayoutChild,
@@ -565,7 +568,8 @@ class RenderAspectRatio extends RenderProxyBox {
   }
 
   @override
-  Size computeDryLayout(BoxConstraints constraints) {
+  @protected
+  Size computeDryLayout(covariant BoxConstraints constraints) {
     return _applyAspectRatio(constraints);
   }
 
@@ -726,7 +730,8 @@ class RenderIntrinsicWidth extends RenderProxyBox {
   }
 
   @override
-  Size computeDryLayout(BoxConstraints constraints) {
+  @protected
+  Size computeDryLayout(covariant BoxConstraints constraints) {
     return _computeSize(
       layoutChild: ChildLayoutHelper.dryLayoutChild,
       constraints: constraints,
@@ -826,7 +831,8 @@ class RenderIntrinsicHeight extends RenderProxyBox {
   }
 
   @override
-  Size computeDryLayout(BoxConstraints constraints) {
+  @protected
+  Size computeDryLayout(covariant BoxConstraints constraints) {
     return _computeSize(
       layoutChild: ChildLayoutHelper.dryLayoutChild,
       constraints: constraints,
@@ -2672,7 +2678,8 @@ class RenderFittedBox extends RenderProxyBox {
   // TODO(ianh): The intrinsic dimensions of this box are wrong.
 
   @override
-  Size computeDryLayout(BoxConstraints constraints) {
+  @protected
+  Size computeDryLayout(covariant BoxConstraints constraints) {
     if (child != null) {
       final Size childSize = child!.getDryLayout(const BoxConstraints());
 
@@ -3693,7 +3700,8 @@ class RenderOffstage extends RenderProxyBox {
   bool get sizedByParent => offstage;
 
   @override
-  Size computeDryLayout(BoxConstraints constraints) {
+  @protected
+  Size computeDryLayout(covariant BoxConstraints constraints) {
     if (offstage) {
       return constraints.smallest;
     }

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

@@ -4,6 +4,7 @@
 
 import 'dart:math' as math;
 
+import 'package:flutter/foundation.dart';
 import 'package:vector_math/vector_math_64.dart';
 
 import 'box.dart';
@@ -74,7 +75,8 @@ class RenderRotatedBox extends RenderBox with RenderObjectWithChildMixin<RenderB
   Matrix4? _paintTransform;
 
   @override
-  Size computeDryLayout(BoxConstraints constraints) {
+  @protected
+  Size computeDryLayout(covariant BoxConstraints constraints) {
     if (child == null) {
       return constraints.smallest;
     }

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

@@ -205,7 +205,8 @@ class RenderPadding extends RenderShiftedBox {
   }
 
   @override
-  Size computeDryLayout(BoxConstraints constraints) {
+  @protected
+  Size computeDryLayout(covariant BoxConstraints constraints) {
     _resolve();
     assert(_resolvedPadding != null);
     if (child == null) {
@@ -428,7 +429,8 @@ class RenderPositionedBox extends RenderAligningShiftedBox {
   }
 
   @override
-  Size computeDryLayout(BoxConstraints constraints) {
+  @protected
+  Size computeDryLayout(covariant BoxConstraints constraints) {
     final bool shrinkWrapWidth = _widthFactor != null || constraints.maxWidth == double.infinity;
     final bool shrinkWrapHeight = _heightFactor != null || constraints.maxHeight == double.infinity;
     if (child != null) {
@@ -637,7 +639,8 @@ class RenderConstrainedOverflowBox extends RenderAligningShiftedBox {
   bool get sizedByParent => true;
 
   @override
-  Size computeDryLayout(BoxConstraints constraints) {
+  @protected
+  Size computeDryLayout(covariant BoxConstraints constraints) {
     return constraints.biggest;
   }
 
@@ -772,7 +775,8 @@ class RenderConstraintsTransformBox extends RenderAligningShiftedBox with DebugO
   }
 
   @override
-  Size computeDryLayout(BoxConstraints constraints) {
+  @protected
+  Size computeDryLayout(covariant BoxConstraints constraints) {
     final Size? childSize = child?.getDryLayout(constraintsTransform(constraints));
     return childSize == null ? constraints.smallest : constraints.constrain(childSize);
   }
@@ -940,7 +944,8 @@ class RenderSizedOverflowBox extends RenderAligningShiftedBox {
   }
 
   @override
-  Size computeDryLayout(BoxConstraints constraints) {
+  @protected
+  Size computeDryLayout(covariant BoxConstraints constraints) {
     return constraints.constrain(_requestedSize);
   }
 
@@ -1089,7 +1094,8 @@ class RenderFractionallySizedOverflowBox extends RenderAligningShiftedBox {
   }
 
   @override
-  Size computeDryLayout(BoxConstraints constraints) {
+  @protected
+  Size computeDryLayout(covariant BoxConstraints constraints) {
     if (child != null) {
       final Size childSize = child!.getDryLayout(_getInnerConstraints(constraints));
       return constraints.constrain(childSize);
@@ -1288,7 +1294,8 @@ class RenderCustomSingleChildLayoutBox extends RenderShiftedBox {
   }
 
   @override
-  Size computeDryLayout(BoxConstraints constraints) {
+  @protected
+  Size computeDryLayout(covariant BoxConstraints constraints) {
     return _getSize(constraints);
   }
 
@@ -1355,7 +1362,8 @@ class RenderBaseline extends RenderShiftedBox {
   }
 
   @override
-  Size computeDryLayout(BoxConstraints constraints) {
+  @protected
+  Size computeDryLayout(covariant BoxConstraints constraints) {
     if (child != null) {
       assert(debugCannotComputeDryLayout(
         reason: 'Baseline metrics are only available after a full layout.',

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

@@ -547,7 +547,8 @@ class RenderStack extends RenderBox
   }
 
   @override
-  Size computeDryLayout(BoxConstraints constraints) {
+  @protected
+  Size computeDryLayout(covariant BoxConstraints constraints) {
     return _computeSize(
       constraints: constraints,
       layoutChild: ChildLayoutHelper.dryLayoutChild,

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

@@ -1024,7 +1024,8 @@ class RenderTable extends RenderBox {
   }
 
   @override
-  Size computeDryLayout(BoxConstraints constraints) {
+  @protected
+  Size computeDryLayout(covariant BoxConstraints constraints) {
     if (rows * columns == 0) {
       return constraints.constrain(Size.zero);
     }

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

@@ -2,6 +2,8 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
+import 'package:flutter/foundation.dart';
+
 import 'box.dart';
 import 'layer.dart';
 import 'object.dart';
@@ -84,7 +86,8 @@ class TextureBox extends RenderBox {
   bool get isRepaintBoundary => true;
 
   @override
-  Size computeDryLayout(BoxConstraints constraints) {
+  @protected
+  Size computeDryLayout(covariant BoxConstraints constraints) {
     return constraints.biggest;
   }
 

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

@@ -1411,7 +1411,8 @@ class RenderViewport extends RenderViewportBase<SliverPhysicalContainerParentDat
   bool get sizedByParent => true;
 
   @override
-  Size computeDryLayout(BoxConstraints constraints) {
+  @protected
+  Size computeDryLayout(covariant BoxConstraints constraints) {
     assert(debugCheckHasBoundedAxis(axis, constraints));
     return constraints.biggest;
   }

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

@@ -4,6 +4,8 @@
 
 import 'dart:math' as math;
 
+import 'package:flutter/foundation.dart';
+
 import 'box.dart';
 import 'layer.dart';
 import 'layout_helper.dart';
@@ -493,7 +495,8 @@ class RenderWrap extends RenderBox
   bool _hasVisualOverflow = false;
 
   @override
-  Size computeDryLayout(BoxConstraints constraints) {
+  @protected
+  Size computeDryLayout(covariant BoxConstraints constraints) {
     return _computeDryLayout(constraints);
   }
 

packages/flutter/test/rendering/editable_test.dart

@@ -1825,11 +1825,13 @@ void main() {
     );
     layout(editable, constraints: constraints);
 
+    // ignore: invalid_use_of_protected_member
     final double initialWidth = editable.computeDryLayout(constraints).width;
     expect(initialWidth, 500);
 
     // Turn off forceLine. Now the width should be significantly smaller.
     editable.forceLine = false;
+    // ignore: invalid_use_of_protected_member
     expect(editable.computeDryLayout(constraints).width, lessThan(initialWidth));
   });
 

packages/flutter/test/rendering/proxy_box_test.dart

@@ -961,10 +961,17 @@ void main() {
     expect(fancyProxyBox.fancyMethod(), 36);
     // Box has behavior from RenderProxyBox:
     expect(
+      // ignore: invalid_use_of_protected_member
       fancyProxyBox.computeDryLayout(const BoxConstraints(minHeight: 8)),
       const Size(0, 8),
     );
   });
+
+  test('computeDryLayout constraints are covariant', () {
+    final RenderBoxWithTestConstraints box = RenderBoxWithTestConstraints();
+    const TestConstraints constraints = TestConstraints(testValue: 6);
+    expect(box.computeDryLayout(constraints), const Size.square(6));
+  });
 }
 
 class _TestRectClipper extends CustomClipper<Rect> {
@@ -1087,3 +1094,19 @@ void expectAssertionError() {
 }
 
 typedef DebugPaintCallback = void Function(PaintingContext context, Offset offset);
+
+class TestConstraints extends BoxConstraints {
+  const TestConstraints({
+    double extent = 100,
+    required this.testValue,
+  }) : super(maxWidth: extent, maxHeight: extent);
+
+  final double testValue;
+}
+
+class RenderBoxWithTestConstraints extends RenderProxyBox {
+  @override
+  Size computeDryLayout(TestConstraints constraints) {
+    return constraints.constrain(Size.square(constraints.testValue));
+  }
+}