Use protected and mustCallSuper in more places (#4291)

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

@@ -97,6 +97,7 @@ class AbstractNode {
   AbstractNode get parent => _parent;
 
   /// Subclasses should call this function when they acquire a new child.
+  @mustCallSuper
   void adoptChild(AbstractNode child) {
     assert(child != null);
     assert(child._parent == null);
@@ -114,6 +115,7 @@ class AbstractNode {
   }
 
   /// Subclasses should call this function when they lose a child.
+  @mustCallSuper
   void dropChild(AbstractNode child) {
     assert(child != null);
     assert(child._parent == this);

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

@@ -1169,19 +1169,24 @@ abstract class RenderObject extends AbstractNode implements HitTestTarget {
     }
   }
 
-  bool _needsLayout = true;
   /// Whether this render object's layout information is dirty.
   bool get needsLayout => _needsLayout;
+  bool _needsLayout = true;
+
   RenderObject _relayoutSubtreeRoot;
   bool _doingThisLayoutWithCallback = false;
-  Constraints _constraints;
+
   /// The layout constraints most recently supplied by the parent.
+  @protected
   Constraints get constraints => _constraints;
+  Constraints _constraints;
+
   /// Verify that the object's constraints are being met. Override
   /// this function in a subclass to verify that your state matches
   /// the constraints object. This function is only called in checked
   /// mode and only when needsLayout is false. If the constraints are
   /// not met, it should assert or throw an exception.
+  @protected
   void debugAssertDoesMeetConstraints();
 
   /// When true, debugAssertDoesMeetConstraints() is currently
@@ -1449,6 +1454,7 @@ abstract class RenderObject extends AbstractNode implements HitTestTarget {
   /// Returning false is always correct, but returning true can be more
   /// efficient when computing the size of this render object because we don't
   /// need to recompute the size if the constraints don't change.
+  @protected
   bool get sizedByParent => false;
 
   /// Updates the render objects size using only the constraints.
@@ -1566,6 +1572,7 @@ abstract class RenderObject extends AbstractNode implements HitTestTarget {
   ///
   /// You must call markNeedsCompositingBitsUpdate() if the value of this
   /// getter changes.
+  @protected
   bool get alwaysNeedsCompositing => false;
 
   OffsetLayer _layer;

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

@@ -4,6 +4,7 @@
 
 import 'dart:ui' as ui show window;
 
+import 'package:meta/meta.dart';
 import 'package:vector_math/vector_math_64.dart';
 
 import 'box.dart';
@@ -355,6 +356,7 @@ abstract class RenderVirtualViewport<T extends ContainerBoxParentDataMixin<Rende
   /// This is a convenience function for subclasses to call from their
   /// intrinsic-sizing functions if they don't have a good way to generate the
   /// numbers.
+  @protected
   bool debugThrowIfNotCheckingIntrinsics() {
     assert(() {
       if (!RenderObject.debugCheckingIntrinsics) {
@@ -372,25 +374,25 @@ abstract class RenderVirtualViewport<T extends ContainerBoxParentDataMixin<Rende
 
   @override
   double getMinIntrinsicWidth(double height) {
-    assert(debugThrowIfNotCheckingIntrinsics);
+    assert(debugThrowIfNotCheckingIntrinsics());
     return 0.0;
   }
 
   @override
   double getMaxIntrinsicWidth(double height) {
-    assert(debugThrowIfNotCheckingIntrinsics);
+    assert(debugThrowIfNotCheckingIntrinsics());
     return 0.0;
   }
 
   @override
   double getMinIntrinsicHeight(double width) {
-    assert(debugThrowIfNotCheckingIntrinsics);
+    assert(debugThrowIfNotCheckingIntrinsics());
     return 0.0;
   }
 
   @override
   double getMaxIntrinsicHeight(double width) {
-    assert(debugThrowIfNotCheckingIntrinsics);
+    assert(debugThrowIfNotCheckingIntrinsics());
     return 0.0;
   }
 

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

@@ -287,8 +287,17 @@ abstract class Widget {
     return '$name(${data.join("; ")})';
   }
 
+  @protected
+  @mustCallSuper
   void debugFillDescription(List<String> description) { }
 
+  /// Lets [Element.debugFillDescription] call the @protected method
+  /// [debugFillDescription]. This pattern prevents other unwanted callers
+  /// outside this library.
+  void _debugFillDescription(List<String> description) {
+    debugFillDescription(description);
+  }
+
   static bool canUpdate(Widget oldWidget, Widget newWidget) {
     return oldWidget.runtimeType == newWidget.runtimeType &&
       oldWidget.key == newWidget.key;
@@ -315,6 +324,7 @@ abstract class StatelessWidget extends Widget {
   /// The given build context object contains information about the location in
   /// the tree at which this widget is being built. For example, the context
   /// provides the set of inherited widgets for this location in the tree.
+  @protected
   Widget build(BuildContext context);
 }
 
@@ -468,11 +478,13 @@ abstract class State<T extends StatefulWidget> {
   /// The context argument is always the same as [State.context]. This argument
   /// is provided redundantly here to match the [WidgetBuilder] function
   /// signature used by [StatelessWidget.build] and other widgets.
+  @protected
   Widget build(BuildContext context);
 
   /// Called when an Inherited widget in the ancestor chain has changed. Usually
   /// there is nothing to do here; whenever this is called, build() is also
   /// called.
+  @mustCallSuper
   void dependenciesChanged() { }
 
   @override
@@ -482,6 +494,8 @@ abstract class State<T extends StatefulWidget> {
     return '$runtimeType(${data.join("; ")})';
   }
 
+  @protected
+  @mustCallSuper
   void debugFillDescription(List<String> description) {
     description.add('$hashCode');
     assert(() {
@@ -961,6 +975,7 @@ abstract class Element implements BuildContext {
   /// The updateChild() method returns the new child, if it had to create one,
   /// or the child that was passed in, if it just had to update the child, or
   /// null, if it removed the child and did not replace it.
+  @protected
   Element updateChild(Element child, Widget newWidget, dynamic newSlot) {
     if (newWidget == null) {
       if (child != null)
@@ -1029,6 +1044,7 @@ abstract class Element implements BuildContext {
   /// Called by MultiChildRenderObjectElement, and other RenderObjectElement
   /// subclasses that have multiple children, to update the slot of a particular
   /// child when the child is moved in its child list.
+  @protected
   void updateSlotForChild(Element child, dynamic newSlot) {
     assert(_debugLifecycleState == _ElementLifecycle.active);
     assert(child != null);
@@ -1088,6 +1104,7 @@ abstract class Element implements BuildContext {
     return element;
   }
 
+  @protected
   Element inflateWidget(Widget newWidget, dynamic newSlot) {
     assert(newWidget != null);
     Key key = newWidget.key;
@@ -1120,6 +1137,7 @@ abstract class Element implements BuildContext {
     });
   }
 
+  @protected
   void deactivateChild(Element child) {
     assert(child != null);
     assert(child._parent == this);
@@ -1184,6 +1202,7 @@ abstract class Element implements BuildContext {
   }
 
   /// Called after children have been deactivated (see [deactivate]).
+  @mustCallSuper
   void debugDeactivated() {
     assert(_debugLifecycleState == _ElementLifecycle.inactive);
   }
@@ -1271,7 +1290,8 @@ abstract class Element implements BuildContext {
       ancestor = ancestor._parent;
   }
 
-  void dependenciesChanged();
+  @mustCallSuper
+  void dependenciesChanged() { }
 
   String debugGetCreatorChain(int limit) {
     List<String> chain = <String>[];
@@ -1297,6 +1317,8 @@ abstract class Element implements BuildContext {
     return '$name(${data.join("; ")})';
   }
 
+  @protected
+  @mustCallSuper
   void debugFillDescription(List<String> description) {
     if (depth == null)
       description.add('no depth');
@@ -1305,7 +1327,7 @@ abstract class Element implements BuildContext {
     } else {
       if (widget.key != null)
         description.add('${widget.key}');
-      widget.debugFillDescription(description);
+      widget._debugFillDescription(description);
     }
   }
 
@@ -1348,6 +1370,7 @@ class ErrorWidget extends LeafRenderObjectWidget {
 
   @override
   void debugFillDescription(List<String> description) {
+    super.debugFillDescription(description);
     description.add('message: ' + _stringify(message));
   }
 }
@@ -1465,10 +1488,12 @@ abstract class BuildableElement extends Element {
   }
 
   /// Called by rebuild() after the appropriate checks have been made.
+  @protected
   void performRebuild();
 
   @override
   void dependenciesChanged() {
+    super.dependenciesChanged();
     assert(_active);
     markNeedsBuild();
   }
@@ -1740,6 +1765,7 @@ abstract class _ProxyElement extends ComponentElement {
     rebuild();
   }
 
+  @protected
   void notifyClients(_ProxyWidget oldWidget);
 }
 
@@ -1835,6 +1861,7 @@ class InheritedElement extends _ProxyElement {
   /// returns true. Subclasses of [InheritedElement] might wish to call this
   /// function at other times if their inherited information changes outside of
   /// the build phase.
+  @protected
   void dispatchDependenciesChanged() {
     for (Element dependent in _dependents) {
       assert(() {
@@ -1886,7 +1913,7 @@ abstract class RenderObjectElement extends BuildableElement {
   void mount(Element parent, dynamic newSlot) {
     super.mount(parent, newSlot);
     _renderObject = widget.createRenderObject(this);
-    assert(() { debugUpdateRenderObjectOwner(); return true; });
+    assert(() { _debugUpdateRenderObjectOwner(); return true; });
     assert(_slot == newSlot);
     attachRenderObject(newSlot);
     _dirty = false;
@@ -1896,12 +1923,12 @@ abstract class RenderObjectElement extends BuildableElement {
   void update(RenderObjectWidget newWidget) {
     super.update(newWidget);
     assert(widget == newWidget);
-    assert(() { debugUpdateRenderObjectOwner(); return true; });
+    assert(() { _debugUpdateRenderObjectOwner(); return true; });
     widget.updateRenderObject(this, renderObject);
     _dirty = false;
   }
 
-  void debugUpdateRenderObjectOwner() {
+  void _debugUpdateRenderObjectOwner() {
     _renderObject.debugCreator = debugGetCreatorChain(10);
   }
 
@@ -1915,6 +1942,7 @@ abstract class RenderObjectElement extends BuildableElement {
   /// Attempts to update the given old children list using the given new
   /// widgets, removing obsolete elements and introducing new ones as necessary,
   /// and then returns the new child list.
+  @protected
   List<Element> updateChildren(List<Element> oldChildren, List<Widget> newWidgets, { Set<Element> detachedChildren }) {
     assert(oldChildren != null);
     assert(newWidgets != null);
@@ -2115,8 +2143,13 @@ abstract class RenderObjectElement extends BuildableElement {
     _slot = null;
   }
 
+  @protected
   void insertChildRenderObject(RenderObject child, dynamic slot);
+
+  @protected
   void moveChildRenderObject(RenderObject child, dynamic slot);
+
+  @protected
   void removeChildRenderObject(RenderObject child);
 
   @override

packages/flutter_markdown/lib/src/markdown_raw.dart

@@ -185,6 +185,7 @@ class _MarkdownBodyRawState extends State<MarkdownBodyRaw> {
 
   @override
   void debugFillDescription(List<String> description) {
+    super.debugFillDescription(description);
     description.add('cached blocks identity: ${_cachedBlocks.hashCode}');
   }
 }