Issue 3446. Recurse into attributes to find children widgets.

R=brianwilkerson@google.com, devoncarew@google.com

Bug: flutter/flutter-intellij#3446
Change-Id: Ifa83367c68b406b342e0f99195015d98eaedb049
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/103900
Reviewed-by: Brian Wilkerson <brianwilkerson@google.com>
Commit-Queue: Konstantin Shcheglov <scheglov@google.com>

Author: scheglov

pkg/analysis_server/lib/src/flutter/flutter_outline_computer.dart

@@ -63,7 +63,20 @@ T _registerWidgetInstance<T extends Widget>(int id, T widget) {
     var flutterDartOutline = _convert(dartOutline);
 
     // Create outlines for widgets.
-    resolvedUnit.unit.accept(new _FlutterOutlineBuilder(this));
+    var visitor = new _FlutterOutlineBuilder(this);
+    resolvedUnit.unit.accept(visitor);
+
+    // Associate Flutter outlines with Dart outlines.
+    for (var outline in visitor.outlines) {
+      for (var parent in _depthFirstOrder) {
+        if (parent.offset < outline.offset &&
+            outline.offset + outline.length < parent.offset + parent.length) {
+          parent.children ??= <protocol.FlutterOutline>[];
+          parent.children.add(outline);
+          break;
+        }
+      }
+    }
 
     // Compute instrumented code.
     if (widgets.values.any((w) => w.hasDesignTimeConstructor)) {
@@ -224,8 +237,14 @@ T _registerWidgetInstance<T extends Widget>(int id, T widget) {
             }
           }
         } else {
-          ParameterElement parameter = argument.staticParameterElement;
-          _addAttribute(attributes, argument, parameter);
+          var visitor = _FlutterOutlineBuilder(this);
+          argument.accept(visitor);
+          if (visitor.outlines.isNotEmpty) {
+            children.addAll(visitor.outlines);
+          } else {
+            ParameterElement parameter = argument.staticParameterElement;
+            _addAttribute(attributes, argument, parameter);
+          }
         }
       }
 
@@ -385,21 +404,15 @@ T _registerWidgetInstance<T extends Widget>(int id, T widget) {
 
 class _FlutterOutlineBuilder extends GeneralizingAstVisitor<void> {
   final FlutterOutlineComputer computer;
+  final List<protocol.FlutterOutline> outlines = [];
 
   _FlutterOutlineBuilder(this.computer);
 
   @override
   void visitExpression(Expression node) {
     var outline = computer._createOutline(node, false);
     if (outline != null) {
-      for (var parent in computer._depthFirstOrder) {
-        if (parent.offset < outline.offset &&
-            outline.offset + outline.length < parent.offset + parent.length) {
-          parent.children ??= <protocol.FlutterOutline>[];
-          parent.children.add(outline);
-          return;
-        }
-      }
+      outlines.add(outline);
     } else {
       super.visitExpression(node);
     }

pkg/analysis_server/test/src/flutter/flutter_outline_computer_test.dart

@@ -205,6 +205,73 @@ class MyWidget extends StatelessWidget {
     }
   }
 
+  test_children_closure_blockBody() async {
+    newFile('/home/test/lib/a.dart', content: r'''
+import 'package:flutter/widgets.dart';
+
+class WidgetA extends StatelessWidget {
+  final Widget Function(bool) factory;
+
+  WidgetA(this.factory);
+}
+''');
+    FlutterOutline unitOutline = await _computeOutline('''
+import 'package:flutter/widgets.dart';
+import 'a.dart';
+
+class MyWidget extends StatelessWidget {
+  @override
+  Widget build(BuildContext context) {
+    return new WidgetA((b) {
+      if (b) {
+        return const Text('aaa'),
+      } else {
+        return const Container(),
+      }
+    }); // WidgetA
+  }
+}
+''');
+    expect(_toText(unitOutline), r'''
+(D) MyWidget
+  (D) build
+    WidgetA
+      Text
+      Container
+''');
+  }
+
+  test_children_closure_expressionBody() async {
+    newFile('/home/test/lib/a.dart', content: r'''
+import 'package:flutter/widgets.dart';
+
+class WidgetA extends StatelessWidget {
+  final Widget Function() factory;
+
+  WidgetA(this.factory);
+}
+''');
+    FlutterOutline unitOutline = await _computeOutline('''
+import 'package:flutter/widgets.dart';
+import 'a.dart';
+
+class MyWidget extends StatelessWidget {
+  @override
+  Widget build(BuildContext context) {
+    return new WidgetA(
+      () => const Text('aaa'),
+    ); // WidgetA
+  }
+}
+''');
+    expect(_toText(unitOutline), r'''
+(D) MyWidget
+  (D) build
+    WidgetA
+      Text
+''');
+  }
+
   test_children_withCollectionElements() async {
     FlutterOutline unitOutline = await _computeOutline('''
 import 'package:flutter/widgets.dart';