Fix for endless recursion for getLayoutExplorerNode on a Tooltip (#131486)

![](https://media.giphy.com/media/l0ExdBwqD6YkeEhQ4/giphy-downsized.gif)

Fixes https://github.com/flutter/devtools/issues/5946

While preparing DevTools for the Multi View changes, I noticed that
inspecting a Tooltip causes an stack overflow.
This PR addresses that issue by fixing the scope of the subtreeDepth variable and adding some other idiomatic fixes

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

@@ -2109,24 +2109,35 @@ mixin WidgetInspectorService {
         summaryTree: true,
         subtreeDepth: subtreeDepth,
         service: this,
-        addAdditionalPropertiesCallback: (DiagnosticsNode node, InspectorSerializationDelegate delegate) {
+        addAdditionalPropertiesCallback:
+            (DiagnosticsNode node, InspectorSerializationDelegate delegate) {
           final Object? value = node.value;
-          final RenderObject? renderObject = value is Element ? value.renderObject : null;
+          final RenderObject? renderObject =
+              value is Element ? value.renderObject : null;
           if (renderObject == null) {
             return const <String, Object>{};
           }
 
-          final DiagnosticsSerializationDelegate renderObjectSerializationDelegate = delegate.copyWith(
+          final DiagnosticsSerializationDelegate
+              renderObjectSerializationDelegate = delegate.copyWith(
             subtreeDepth: 0,
             includeProperties: true,
             expandPropertyValues: false,
           );
           final Map<String, Object> additionalJson = <String, Object>{
-            'renderObject': renderObject.toDiagnosticsNode().toJsonMap(renderObjectSerializationDelegate),
+            // Only include renderObject properties separately if this value is not already the renderObject.
+            // Only include if we are expanding property values to mitigate the risk of infinite loops if
+            // RenderObjects have properties that are Element objects.
+            if (value is! RenderObject && delegate.expandPropertyValues)
+              'renderObject': renderObject
+                  .toDiagnosticsNode()
+                  .toJsonMap(renderObjectSerializationDelegate),
           };
 
           final RenderObject? renderParent = renderObject.parent;
-          if (renderParent is RenderObject && subtreeDepth > 0) {
+          if (renderParent != null &&
+              delegate.subtreeDepth > 0 &&
+              delegate.expandPropertyValues) {
             final Object? parentCreator = renderParent.debugCreator;
             if (parentCreator is DebugCreator) {
               additionalJson['parentRenderElement'] =
@@ -2147,7 +2158,7 @@ mixin WidgetInspectorService {
             if (!renderObject.debugNeedsLayout) {
               // ignore: invalid_use_of_protected_member
               final Constraints constraints = renderObject.constraints;
-              final Map<String, Object>constraintsProperty = <String, Object>{
+              final Map<String, Object> constraintsProperty = <String, Object>{
                 'type': constraints.runtimeType.toString(),
                 'description': constraints.toString(),
               };

packages/flutter/test/widgets/widget_inspector_test.dart

@@ -4771,6 +4771,53 @@ class _TestWidgetInspectorService extends TestWidgetInspectorService {
         }
         expect(error, isNull);
       });
+
+      testWidgets(
+          'ext.flutter.inspector.getLayoutExplorerNode, on a ToolTip, does not throw StackOverflowError',
+          (WidgetTester tester) async {
+        // Regression test for https://github.com/flutter/devtools/issues/5946
+        const Widget widget = MaterialApp(
+          home: Directionality(
+            textDirection: TextDirection.ltr,
+            child: Center(
+              child: Row(
+                children: <Widget>[
+                  Flexible(
+                    child: ColoredBox(
+                      color: Colors.green,
+                      child: Tooltip(
+                        message: 'a',
+                        child: ElevatedButton(
+                          onPressed: null,
+                          child: Text('a'),
+                        ),
+                      ),
+                    ),
+                  ),
+                ],
+              ),
+            ),
+          ),
+        );
+        await tester.pumpWidget(widget);
+
+        final Element elevatedButton =
+            tester.element(find.byType(ElevatedButton).first);
+        service.setSelection(elevatedButton, group);
+
+        final String id = service.toId(elevatedButton, group)!;
+
+        Object? error;
+        try {
+          await service.testExtension(
+            WidgetInspectorServiceExtensions.getLayoutExplorerNode.name,
+            <String, String>{'id': id, 'groupName': group, 'subtreeDepth': '1'},
+          );
+        } catch (e) {
+          error = e;
+        }
+        expect(error, isNull);
+      });
     });
 
     test('ext.flutter.inspector.structuredErrors', () async {