Use DiagnosticableMixin instead of Diagnosticable for some conditionals. (#49726)

This PR fixes #49647 by changing DiagnosticableMixin.toDiagnosticsNode and other things to accept DiagnosticableMixin instead of requiring Diagnosticable.

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

@@ -8,7 +8,7 @@ import 'colors.dart';
 
 /// An [IconThemeData] subclass that automatically resolves its [color] when retrieved
 /// using [IconTheme.of].
-class CupertinoIconThemeData extends IconThemeData with DiagnosticableMixin {
+class CupertinoIconThemeData extends IconThemeData with DiagnosticableMixin implements Diagnosticable {
   /// Creates a [CupertinoIconThemeData].
   ///
   /// The opacity applies to both explicit and default icon colors. The value

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

@@ -351,7 +351,7 @@ class FlutterErrorDetails extends Diagnosticable {
     return longMessage;
   }
 
-  Diagnosticable _exceptionToDiagnosticable() {
+  DiagnosticableMixin _exceptionToDiagnosticable() {
     if (exception is FlutterError) {
       return exception as FlutterError;
     }
@@ -374,7 +374,7 @@ class FlutterErrorDetails extends Diagnosticable {
     if (kReleaseMode) {
       return DiagnosticsNode.message(formatException());
     }
-    final Diagnosticable diagnosticable = _exceptionToDiagnosticable();
+    final DiagnosticableMixin diagnosticable = _exceptionToDiagnosticable();
     DiagnosticsNode summary;
     if (diagnosticable != null) {
       final DiagnosticPropertiesBuilder builder = DiagnosticPropertiesBuilder();
@@ -388,7 +388,7 @@ class FlutterErrorDetails extends Diagnosticable {
   void debugFillProperties(DiagnosticPropertiesBuilder properties) {
     super.debugFillProperties(properties);
     final DiagnosticsNode verb = ErrorDescription('thrown${ context != null ? ErrorDescription(" $context") : ""}');
-    final Diagnosticable diagnosticable = _exceptionToDiagnosticable();
+    final DiagnosticableMixin diagnosticable = _exceptionToDiagnosticable();
     if (exception is NullThrownError) {
       properties.add(ErrorDescription('The null value was $verb.'));
     } else if (exception is num) {

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

@@ -2640,7 +2640,7 @@ class DiagnosticsProperty<T> extends DiagnosticsNode {
   Map<String, Object> toJsonMap(DiagnosticsSerializationDelegate delegate) {
     final T v = value;
     List<Map<String, Object>> properties;
-    if (delegate.expandPropertyValues && delegate.includeProperties && v is Diagnosticable && getProperties().isEmpty) {
+    if (delegate.expandPropertyValues && delegate.includeProperties && v is DiagnosticableMixin && getProperties().isEmpty) {
       // Exclude children for expanded nodes to avoid cycles.
       delegate = delegate.copyWith(subtreeDepth: 0, includeProperties: false);
       properties = DiagnosticsNode.toJsonList(
@@ -2666,7 +2666,7 @@ class DiagnosticsProperty<T> extends DiagnosticsNode {
       json['exception'] = exception.toString();
     json['propertyType'] = propertyType.toString();
     json['defaultLevel'] = describeEnum(_defaultLevel);
-    if (value is Diagnosticable || value is DiagnosticsNode)
+    if (value is DiagnosticableMixin || value is DiagnosticsNode)
       json['isDiagnosticableValue'] = true;
     if (v is num)
       // Workaround for https://github.com/flutter/flutter/issues/39937#issuecomment-529558033.
@@ -2846,7 +2846,7 @@ class DiagnosticsProperty<T> extends DiagnosticsNode {
       if (object is DiagnosticsNode) {
         return object.getProperties();
       }
-      if (object is Diagnosticable) {
+      if (object is DiagnosticableMixin) {
         return object.toDiagnosticsNode(style: style).getProperties();
       }
     }
@@ -2860,7 +2860,7 @@ class DiagnosticsProperty<T> extends DiagnosticsNode {
       if (object is DiagnosticsNode) {
         return object.getChildren();
       }
-      if (object is Diagnosticable) {
+      if (object is DiagnosticableMixin) {
         return object.toDiagnosticsNode(style: style).getChildren();
       }
     }
@@ -2870,8 +2870,8 @@ class DiagnosticsProperty<T> extends DiagnosticsNode {
 
 /// [DiagnosticsNode] that lazily calls the associated [Diagnosticable] [value]
 /// to implement [getChildren] and [getProperties].
-class DiagnosticableNode<T extends Diagnosticable> extends DiagnosticsNode {
-  /// Create a diagnostics describing a [Diagnosticable] value.
+class DiagnosticableNode<T extends DiagnosticableMixin> extends DiagnosticsNode {
+  /// Create a diagnostics describing a [DiagnosticableMixin] value.
   ///
   /// The [value] argument must not be null.
   DiagnosticableNode({
@@ -2991,7 +2991,7 @@ String describeEnum(Object enumEntry) {
 }
 
 /// Builder to accumulate properties and configuration used to assemble a
-/// [DiagnosticsNode] from a [Diagnosticable] object.
+/// [DiagnosticsNode] from a [DiagnosticableMixin] object.
 class DiagnosticPropertiesBuilder {
   /// Creates a [DiagnosticPropertiesBuilder] with [properties] initialize to
   /// an empty array.
@@ -3053,10 +3053,8 @@ abstract class Diagnosticable with DiagnosticableMixin {
   const Diagnosticable();
 }
 
-/// A mixin class that provides the implementation for [Diagnosticable].
-///
-/// This mixin can be used to add diagnostics to a class which already has an
-/// base class.
+/// A mixin class for providing string and [DiagnosticsNode] debug
+/// representations describing the properties of an object.
 ///
 /// The string debug representation is generated from the intermediate
 /// [DiagnosticsNode] representation. The [DiagnosticsNode] representation is
@@ -3108,9 +3106,9 @@ mixin DiagnosticableMixin {
   /// relationship between the parent and the node. For example, pass
   /// [DiagnosticsTreeStyle.offstage] to indicate that a node is offstage.
   DiagnosticsNode toDiagnosticsNode({ String name, DiagnosticsTreeStyle style }) {
-    return DiagnosticableNode<Diagnosticable>(
+    return DiagnosticableNode<DiagnosticableMixin>(
       name: name,
-      value: this as Diagnosticable,
+      value: this,
       style: style,
     );
   }
@@ -3338,8 +3336,8 @@ mixin DiagnosticableMixin {
 /// See also:
 ///
 ///  * [DiagnosticableTreeMixin], a mixin that implements this class.
-///  * [Diagnosticable], which should be used instead of this class to provide
-///    diagnostics for objects without children.
+///  * [DiagnosticableMixin], which should be used instead of this class to
+///    provide diagnostics for objects without children.
 abstract class DiagnosticableTree extends Diagnosticable {
   /// Abstract const constructor. This constructor enables subclasses to provide
   /// const constructors so that they can be used in const expressions.
@@ -3643,7 +3641,7 @@ abstract class DiagnosticsSerializationDelegate {
   ///    will be included.
   bool get includeProperties;
 
-  /// Whether properties that have a [Diagnosticable] as value should be
+  /// Whether properties that have a [DiagnosticableMixin] as value should be
   /// expanded.
   bool get expandPropertyValues;
 

packages/flutter/lib/src/scheduler/ticker.dart

@@ -38,7 +38,7 @@ abstract class TickerProvider {
   Ticker createTicker(TickerCallback onTick);
 }
 
-// TODO(jacobr): make Ticker Diagnosticable to simplify reporting errors
+// TODO(jacobr): make Ticker use DiagnosticableMixin to simplify reporting errors
 // related to a ticker.
 /// Calls its callback once per animation frame.
 ///

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

@@ -110,7 +110,7 @@ class KeySet<T extends KeyboardKey> {
 /// This is a thin wrapper around a [Set], but changes the equality comparison
 /// from an identity comparison to a contents comparison so that non-identical
 /// sets with the same keys in them will compare as equal.
-class LogicalKeySet extends KeySet<LogicalKeyboardKey> with DiagnosticableMixin {
+class LogicalKeySet extends KeySet<LogicalKeyboardKey> with DiagnosticableMixin implements Diagnosticable {
   /// A constructor for making a [LogicalKeySet] of up to four keys.
   ///
   /// If you need a set of more than four keys, use [LogicalKeySet.fromSet].
@@ -201,7 +201,7 @@ class ShortcutMapProperty extends DiagnosticsProperty<Map<LogicalKeySet, Intent>
 ///
 /// A [ShortcutManager] is obtained by calling [Shortcuts.of] on the context of
 /// the widget that you want to find a manager for.
-class ShortcutManager extends ChangeNotifier with DiagnosticableMixin {
+class ShortcutManager extends ChangeNotifier with DiagnosticableMixin implements Diagnosticable {
   /// Constructs a [ShortcutManager].
   ///
   /// The [shortcuts] argument must not  be null.

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

@@ -635,7 +635,7 @@ class _DiagnosticsPathNode {
 }
 
 List<_DiagnosticsPathNode> _followDiagnosticableChain(
-  List<Diagnosticable> chain, {
+  List<DiagnosticableMixin> chain, {
   String name,
   DiagnosticsTreeStyle style,
 }) {
@@ -644,7 +644,7 @@ List<_DiagnosticsPathNode> _followDiagnosticableChain(
     return path;
   DiagnosticsNode diagnostic = chain.first.toDiagnosticsNode(name: name, style: style);
   for (int i = 1; i < chain.length; i += 1) {
-    final Diagnosticable target = chain[i];
+    final DiagnosticableMixin target = chain[i];
     bool foundMatch = false;
     final List<DiagnosticsNode> children = diagnostic.getChildren();
     for (int j = 0; j < children.length; j += 1) {
@@ -1550,7 +1550,7 @@ mixin WidgetInspectorService {
       return true;
     }
     final Object value = node.value;
-    if (value is! Diagnosticable) {
+    if (value is! DiagnosticableMixin) {
       return true;
     }
     if (value is! Element || !isWidgetCreationTracked()) {

packages/flutter/test/foundation/diagnostics_test.dart

@@ -180,7 +180,7 @@ void validatePropertyJsonSerializationHelper(final Map<String, Object> json, Dia
   }
   expect(json['propertyType'], equals(property.propertyType.toString()));
   expect(json.containsKey('defaultLevel'), isTrue);
-  if (property.value is Diagnosticable) {
+  if (property.value is DiagnosticableMixin) {
     expect(json['isDiagnosticableValue'], isTrue);
   } else {
     expect(json.containsKey('isDiagnosticableValue'), isFalse);

packages/flutter/test/widgets/shortcuts_test.dart

@@ -322,5 +322,29 @@ void main() {
       expect(description.length, equals(1));
       expect(description[0], equals('shortcuts: <Debug Label>'));
     });
+    test('Shortcuts diagnostics work when manager specified.', () {
+      final DiagnosticPropertiesBuilder builder = DiagnosticPropertiesBuilder();
+
+      Shortcuts(
+        manager: ShortcutManager(),
+        shortcuts: <LogicalKeySet, Intent>{
+          LogicalKeySet(
+            LogicalKeyboardKey.keyA,
+            LogicalKeyboardKey.keyB,
+          ): const Intent(ActivateAction.key)
+        },
+      ).debugFillProperties(builder);
+
+      final List<String> description = builder.properties
+          .where((DiagnosticsNode node) {
+        return !node.isFiltered(DiagnosticLevel.info);
+      })
+          .map((DiagnosticsNode node) => node.toString())
+          .toList();
+
+      expect(description.length, equals(2));
+      expect(description[0], equalsIgnoringHashCodes('manager: ShortcutManager#00000(shortcuts: {})'));
+      expect(description[1], equalsIgnoringHashCodes('shortcuts: {{Key A + Key B}: Intent#00000(key: [<ActivateAction>])}'));
+    });
   });
 }