Ignore text selection boxes when assembling semantics for placeholder runs (#70487)

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

@@ -902,13 +902,33 @@ class RenderParagraph extends RenderBox
     RenderBox? child = firstChild;
     final Queue<SemanticsNode> newChildCache = Queue<SemanticsNode>();
     for (final InlineSpanSemanticsInformation info in _combineSemanticsInfo()) {
-      final TextDirection initialDirection = currentDirection;
       final TextSelection selection = TextSelection(
         baseOffset: start,
         extentOffset: start + info.text.length,
       );
-      final List<ui.TextBox> rects = getBoxesForSelection(selection);
       start += info.text.length;
+
+      if (info.isPlaceholder) {
+        // A placeholder span may have 0 to multple semantics nodes, we need
+        // to annotate all of the semantics nodes belong to this span.
+        while (children.length > childIndex &&
+               children.elementAt(childIndex).isTagged(PlaceholderSpanIndexSemanticsTag(placeholderIndex))) {
+          final SemanticsNode childNode = children.elementAt(childIndex);
+          final TextParentData parentData = child!.parentData! as TextParentData;
+          childNode.rect = Rect.fromLTWH(
+            childNode.rect.left,
+            childNode.rect.top,
+            childNode.rect.width * parentData.scale!,
+            childNode.rect.height * parentData.scale!,
+          );
+          newChildren.add(childNode);
+          childIndex += 1;
+        }
+        child = childAfter(child!);
+        placeholderIndex += 1;
+      } else {
+        final TextDirection initialDirection = currentDirection;
+        final List<ui.TextBox> rects = getBoxesForSelection(selection);
         if (rects.isEmpty) {
           continue;
         }
@@ -934,26 +954,6 @@ class RenderParagraph extends RenderBox
           rect.right.ceilToDouble() + 4.0,
           rect.bottom.ceilToDouble() + 4.0,
         );
-
-      if (info.isPlaceholder) {
-        // A placeholder span may have 0 to multple semantics nodes, we need
-        // to annotate all of the semantics nodes belong to this span.
-        while (children.length > childIndex &&
-               children.elementAt(childIndex).isTagged(PlaceholderSpanIndexSemanticsTag(placeholderIndex))) {
-          final SemanticsNode childNode = children.elementAt(childIndex);
-          final TextParentData parentData = child!.parentData! as TextParentData;
-          childNode.rect = Rect.fromLTWH(
-            childNode.rect.left,
-            childNode.rect.top,
-            childNode.rect.width * parentData.scale!,
-            childNode.rect.height * parentData.scale!,
-          );
-          newChildren.add(childNode);
-          childIndex += 1;
-        }
-        child = childAfter(child!);
-        placeholderIndex += 1;
-      } else {
         final SemanticsConfiguration configuration = SemanticsConfiguration()
           ..sortKey = OrdinalSortKey(ordinal++)
           ..textDirection = initialDirection

packages/flutter/test/rendering/paragraph_test.dart

@@ -37,6 +37,26 @@ class RenderParagraphWithEmptySelectionBoxList extends RenderParagraph {
   }
 }
 
+// A subclass of RenderParagraph that returns an empty list in getBoxesForSelection
+// for a selection representing a WidgetSpan.
+// This is intended to simulate how SkParagraph's implementation of Paragraph.getBoxesForRange
+// can return an empty list for a WidgetSpan with empty dimensions.
+class RenderParagraphWithEmptyBoxListForWidgetSpan extends RenderParagraph {
+  RenderParagraphWithEmptyBoxListForWidgetSpan(
+    InlineSpan text, {
+    required List<RenderBox> children,
+    required TextDirection textDirection,
+  }) : super(text, children: children, textDirection: textDirection);
+
+  @override
+  List<ui.TextBox> getBoxesForSelection(TextSelection selection) {
+    if (text.getSpanForPosition(selection.base) is WidgetSpan) {
+      return <ui.TextBox>[];
+    }
+    return super.getBoxesForSelection(selection);
+  }
+}
+
 void main() {
   test('getOffsetForCaret control test', () {
     final RenderParagraph paragraph = RenderParagraph(
@@ -588,4 +608,25 @@ void main() {
     paragraph.assembleSemanticsNode(node, SemanticsConfiguration(), <SemanticsNode>[]);
     expect(node.childrenCount, 2);
   }, skip: isBrowser); // https://github.com/flutter/flutter/issues/61020
+
+  test('assembleSemanticsNode handles empty WidgetSpans that do not yield selection boxes', () {
+    final TextSpan text = TextSpan(text: '', children: <InlineSpan>[
+      TextSpan(text: 'A', recognizer: TapGestureRecognizer()..onTap = () {}),
+      const WidgetSpan(child: SizedBox(width: 0, height: 0)),
+      TextSpan(text: 'C', recognizer: TapGestureRecognizer()..onTap = () {}),
+    ]);
+    final List<RenderBox> renderBoxes = <RenderBox>[
+      RenderParagraph(const TextSpan(text: 'b'), textDirection: TextDirection.ltr),
+    ];
+    final RenderParagraph paragraph = RenderParagraphWithEmptyBoxListForWidgetSpan(
+      text,
+      children: renderBoxes,
+      textDirection: TextDirection.ltr,
+    );
+    layout(paragraph);
+
+    final SemanticsNode node = SemanticsNode();
+    paragraph.assembleSemanticsNode(node, SemanticsConfiguration(), <SemanticsNode>[]);
+    expect(node.childrenCount, 2);
+  }, skip: isBrowser); // https://github.com/flutter/flutter/issues/61020
 }