It looks like this pull request may not have tests. Please make sure to add tests before merging. If you need an exemption to this rule, contact Hixie on the #hackers channel in Chat.

If you are not sure if you need tests, consider this rule of thumb: the purpose of a test is to make sure someone doesn't accidentally revert the fix. Ask yourself, is there anything in your PR that you feel it is important we not accidentally revert back to how it was before your fix?

Reviewers: Read the Tree Hygiene page and make sure this patch meets those guidelines before LGTMing.

cc: @Piinks

I can see ClipRect was added in https://github.com/flutter/flutter/pull/66504/files#diff-f28e065ae18b9a43c269b6b6e56ceb417084872226ea345fd3e3e207837f0f3dR563

Is it necessary for Hero transition? Is this a good change? If you have any alternative fix

Gold has detected about 6 new digest(s) on patchset 1.
View them at https://flutter-gold.skia.org/cl/github/94811

Golden file changes have been found for this pull request. Click here to view and triage (e.g. because this is an intentional change).

If you are still iterating on this change and are not ready to resolve the images on the Flutter Gold dashboard, consider marking this PR as a draft pull request above. You will still be able to view image results on the dashboard, commenting will be silenced, and the check will not try to resolve itself until marked ready for review.

For more guidance, visit Writing a golden file test for package:flutter.

Reviewers: Read the Tree Hygiene page and make sure this patch meets those guidelines before LGTMing.

Changes reported for pull request #94811 at sha 7409d4e

I don't think it was necessary for the Hero, the ClipRect was already there before I made that change.

@Piinks
Thanks so much for the feedback, I just realized, it wasn't added but kept

I already looked into #47202 and its PRs, it seems to be a related position indeed and it shows shadow being clipped at the bottom by navigation but the new issue is only reproducible when you force a width and horizontal sides are clipped (this parameter wasn't available in that version of Fluttter where this was handled).

This seems to be a common issue that also affects other widgets with elevation too

Here I created a basic code sample that doesn't use Snackbar at all, just to demonstrate what's happening with ClipRect and container without horizontal margin and this issue seems to beyond Snackbar since it would affect any widget with elevation

import 'package:flutter/material.dart';

void main() => runApp(const MyApp());

class MyApp extends StatelessWidget {
  const MyApp({Key? key}) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return const MaterialApp(
      title: 'Material App',
      home: Home(),
    );
  }
}

class Home extends StatelessWidget {
  const Home({Key? key}) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: const Text('Material App Bar'),
      ),
      body: Center(
        child: Column(
          mainAxisAlignment: MainAxisAlignment.spaceEvenly,
          children: [
            ClipRect(
              child: Container(
                margin: const EdgeInsets.only(bottom: 15, top: 10),
                width: 300,
                child: const Material(
                    elevation: 8,
                    shape: RoundedRectangleBorder(),
                    child: Padding(
                      padding: EdgeInsets.all(8.0),
                      child:
                          Text('ClipRect > Container(width: 300) > Material'),
                    )),
              ),
            ),
            Container(
              margin: const EdgeInsets.only(bottom: 15, top: 10),
              width: 300,
              child: const Material(
                  elevation: 8,
                  shape: RoundedRectangleBorder(),
                  child: Padding(
                    padding: EdgeInsets.all(8.0),
                    child: Text('Container(width: 300) > Material'),
                  )),
            ),
            ClipRect(
              child: Container(
                margin: const EdgeInsets.only(bottom: 15, top: 10, left: 15, right: 15),
                child: const Material(
                    elevation: 8,
                    shape: RoundedRectangleBorder(),
                    child: Padding(
                      padding: EdgeInsets.all(8.0),
                      child: Text('Container with horizontal margins > Material'),
                    )),
              ),
            ),
          ],
        ),
      ),
    );
  }
}

Gold has detected about 10 new digest(s) on patchset 2.
View them at https://flutter-gold.skia.org/cl/github/94811

Golden file changes are available for triage from new commit, Click here to view.

For more guidance, visit Writing a golden file test for package:flutter.

Reviewers: Read the Tree Hygiene page and make sure this patch meets those guidelines before LGTMing.

Changes reported for pull request #94811 at sha cafd91a

@Piinks
Thanks for the suggestion, without container, there are still golden test diffs

test-exempt: is tested (gold)

Looks like this also breaks some Google-internal tests, you'll need to ask someone to take a look at those to see if it's anything serious or just more golden tests. Ask around in #hackers-tests.

Thanks @Hixie! I have taken a look at the Google-internal failures. They all look as expected, there is just a sliver of shadow that was previously being clipped incorrectly, similar to the golden file updates here.
Will manually set the check to green here and follow up when it rolls. 👍

If there is a BackdropFilter involved it will suddenly blur the entire screen rather than just the contents under the widget. As per BackdropFilter:

The filter will be applied to all the area within its parent or ancestor widget's clip. If there's no clip, the filter will be applied to the full screen.

In fact, this change caused a customer issue of this exact nature: #98205