Make _RenderCustomClip respect clipBehavior (#103748)

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

@@ -1404,8 +1404,15 @@ abstract class _RenderCustomClip<T> extends RenderProxyBox {
   }
 
   @override
-  Rect describeApproximatePaintClip(RenderObject child) {
-    return _clipper?.getApproximateClipRect(size) ?? Offset.zero & size;
+  Rect? describeApproximatePaintClip(RenderObject child) {
+    switch (clipBehavior) {
+      case Clip.none:
+        return null;
+      case Clip.hardEdge:
+      case Clip.antiAlias:
+      case Clip.antiAliasWithSaveLayer:
+        return _clipper?.getApproximateClipRect(size) ?? Offset.zero & size;
+    }
   }
 
   Paint? _debugPaint;

packages/flutter/test/rendering/proxy_box_test.dart

@@ -686,6 +686,31 @@ void main() {
 
     expect(() => pumpFrame(phase: EnginePhase.composite), returnsNormally);
   });
+
+  test('RenderCustomClip extenders respect clipBehavior when asked to describeApproximateClip', () {
+    final RenderBox child = RenderConstrainedBox(additionalConstraints: const BoxConstraints.tightFor(width: 200, height: 200));
+    final RenderClipRect renderClipRect = RenderClipRect(clipBehavior: Clip.none, child: child);
+    layout(renderClipRect);
+    expect(
+      renderClipRect.describeApproximatePaintClip(child),
+      null,
+    );
+    renderClipRect.clipBehavior = Clip.hardEdge;
+    expect(
+      renderClipRect.describeApproximatePaintClip(child),
+      Offset.zero & renderClipRect.size,
+    );
+    renderClipRect.clipBehavior = Clip.antiAlias;
+    expect(
+      renderClipRect.describeApproximatePaintClip(child),
+      Offset.zero & renderClipRect.size,
+    );
+    renderClipRect.clipBehavior = Clip.antiAliasWithSaveLayer;
+    expect(
+      renderClipRect.describeApproximatePaintClip(child),
+      Offset.zero & renderClipRect.size,
+    );
+  });
 }
 
 class _TestRectClipper extends CustomClipper<Rect> {