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LayoutBuilder's descendant widgets should not rebuild more than once in the same frame #146379

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#147856
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LayoutBuilder's descendant widgets should not rebuild more than once in the same frame#146379
#147856
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LongCatIsLooong
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P2Important issues not at the top of the work lista: tests"flutter test", flutter_test, or one of our testsfound in release: 3.19Found to occur in 3.19found in release: 3.22Found to occur in 3.22frameworkflutter/packages/flutter repository. See also f: labels.has reproducible stepsThe issue has been confirmed reproducible and is ready to work onr: fixedIssue is closed as already fixed in a newer versionteam-frameworkOwned by Framework teamtriaged-frameworkTriaged by Framework team

Description

@LongCatIsLooong
LongCatIsLooong
opened on Apr 6, 2024
  testWidgets('LayoutBuilder rebuids twice', (WidgetTester tester) async {
    int built = 0;
    final target = LayoutBuilder(
      builder: (context, constraints) {
        return Builder(builder: (context) {
          built += 1;
          MediaQuery.of(context);
          return const Placeholder();
        });
      },
    );
    expect(built, 0);

    await tester.pumpWidget(MediaQuery(
      data: const MediaQueryData(size: Size(400.0, 300.0)),
      child: Center(
        child: SizedBox(
          width: 400.0,
          child: target,
        ),
      ),
    ));
    expect(built, 1);

    await tester.pumpWidget(MediaQuery(
      data: const MediaQueryData(size: Size(300.0, 400.0)),
      child: Center(
        child: SizedBox(
          width: 300.0,
          child: target,
        ),
      ),
    ));
    expect(built, 2);
  });

The following TestFailure was thrown running a test:
Expected: <2>
Actual: <3>

This came up again in #143249: we can't use a LayoutBuilder to get the incoming constraints because a google internal test failure caused by this.

This becomes problematic when a disposable object (such as a controller) is passed down the widget tree as a widget parameter, across the LayoutBuilder boundary:

ControllerOwner -> LayoutBuilder -> IntermediateWidget -> ControllerUser.

If ControllerUser rebulids without IntermediateWidget rebuilding (as seen in the test), it may keep using an outdated / disposed controller.

Activity

  1. darshankawar
    added
    in triagePresently being triaged by the triage team
    on Apr 8, 2024

  2. darshankawar commented on Apr 8, 2024

    @darshankawar
    darshankawar
    on Apr 8, 2024
    Member

    I was able to replicate this using the test code provided.

    stable, master flutter doctor -v 
    [!] Flutter (Channel stable, 3.19.5, on macOS 12.2.1 21D62 darwin-x64, locale
    en-GB)
    • Flutter version 3.19.5 on channel stable at
      /Users/dhs/documents/fluttersdk/flutter
    ! Warning: `flutter` on your path resolves to
      /Users/dhs/Documents/Fluttersdk/flutter/bin/flutter, which is not inside
      your current Flutter SDK checkout at
      /Users/dhs/documents/fluttersdk/flutter. Consider adding
      /Users/dhs/documents/fluttersdk/flutter/bin to the front of your path.
    ! Warning: `dart` on your path resolves to
      /Users/dhs/Documents/Fluttersdk/flutter/bin/dart, which is not inside your
      current Flutter SDK checkout at /Users/dhs/documents/fluttersdk/flutter.
      Consider adding /Users/dhs/documents/fluttersdk/flutter/bin to the front
      of your path.
    • Upstream repository https://github.com/flutter/flutter.git
    • Framework revision 300451adae (4 days ago), 2024-03-27 21:54:07 -0500
    • Engine revision e76c956498
    • Dart version 3.3.3
    • DevTools version 2.31.1
    • If those were intentional, you can disregard the above warnings; however
      it is recommended to use "git" directly to perform update checks and
      upgrades.

[!] Xcode - develop for iOS and macOS (Xcode 12.3)
    • Xcode at /Applications/Xcode.app/Contents/Developer
    ! Flutter recommends a minimum Xcode version of 13.
      Download the latest version or update via the Mac App Store.
    • CocoaPods version 1.11.2

[✓] Chrome - develop for the web
    • Chrome at /Applications/Google Chrome.app/Contents/MacOS/Google Chrome

[✓] VS Code (version 1.62.0)
    • VS Code at /Applications/Visual Studio Code.app/Contents
    • Flutter extension version 3.21.0

[✓] Connected device (5 available)
    • SM G975F (mobile)       • RZ8M802WY0X • android-arm64   • Android 11 (API 30)
    • Darshan's iphone (mobile)  • 21150b119064aecc249dfcfe05e259197461ce23 •
      ios            • iOS 14.4.1 18D61
    • iPhone 12 Pro Max (mobile) • A5473606-0213-4FD8-BA16-553433949729     •
      ios            • com.apple.CoreSimulator.SimRuntime.iOS-14-3 (simulator)
    • macOS (desktop)            • macos                                    •
      darwin-x64     • Mac OS X 10.15.4 19E2269 darwin-x64
    • Chrome (web)               • chrome                                   •
      web-javascript • Google Chrome 98.0.4758.80

[✓] HTTP Host Availability
    • All required HTTP hosts are available

! Doctor found issues in 1 category.

[!] Flutter (Channel master, 3.22.0-5.0.pre.55, on macOS 12.2.1 21D62
    darwin-x64, locale en-GB)
    • Flutter version 3.22.0-5.0.pre.55 on channel master at
      /Users/dhs/documents/fluttersdk/flutter
    ! Warning: `flutter` on your path resolves to
      /Users/dhs/Documents/Fluttersdk/flutter/bin/flutter, which is not inside
      your current Flutter SDK checkout at
      /Users/dhs/documents/fluttersdk/flutter. Consider adding
      /Users/dhs/documents/fluttersdk/flutter/bin to the front of your path.
    ! Warning: `dart` on your path resolves to
      /Users/dhs/Documents/Fluttersdk/flutter/bin/dart, which is not inside your
      current Flutter SDK checkout at /Users/dhs/documents/fluttersdk/flutter.
      Consider adding /Users/dhs/documents/fluttersdk/flutter/bin to the front
      of your path.
    • Upstream repository https://github.com/flutter/flutter.git
    • Framework revision ddf79b755d (6 hours ago), 2024-04-07 18:34:24 -0400
    • Engine revision c10e950c66
    • Dart version 3.5.0 (build 3.5.0-18.0.dev)
    • DevTools version 2.34.1
    • If those were intentional, you can disregard the above warnings; however
      it is recommended to use "git" directly to perform update checks and
      upgrades.

[!] Android toolchain - develop for Android devices (Android SDK version 30.0.3)
    • Android SDK at /Users/dhs/Library/Android/sdk
    ✗ cmdline-tools component is missing
      Run `path/to/sdkmanager --install "cmdline-tools;latest"`
      See https://developer.android.com/studio/command-line for more details.
    ✗ Android license status unknown.
      Run `flutter doctor --android-licenses` to accept the SDK licenses.
      See https://flutter.dev/docs/get-started/install/macos#android-setup for
      more details.

[✓] Xcode - develop for iOS and macOS (Xcode 13.2.1)
    • Xcode at /Applications/Xcode.app/Contents/Developer
    • Build 13C100
    • CocoaPods version 1.11.2

[✓] Chrome - develop for the web
    • Chrome at /Applications/Google Chrome.app/Contents/MacOS/Google Chrome

[✓] IntelliJ IDEA Ultimate Edition (version 2021.3.2)
    • IntelliJ at /Applications/IntelliJ IDEA.app
    • Flutter plugin version 65.1.4
    • Dart plugin version 213.7228

[✓] VS Code (version 1.62.0)
    • VS Code at /Applications/Visual Studio Code.app/Contents
    • Flutter extension version 3.29.0

[✓] Connected device (3 available)
    • Darshan's iphone (mobile) • 21150b119064aecc249dfcfe05e259197461ce23 • ios
      • iOS 15.3.1 19D52
    • macOS (desktop)           • macos                                    •
      darwin-x64     • macOS 12.2.1 21D62 darwin-x64
    • Chrome (web)              • chrome                                   •
      web-javascript • Google Chrome 109.0.5414.119

[✓] Network resources
    • All expected network resources are available.

! Doctor found issues in 1 category.
      
[!] Xcode - develop for iOS and macOS (Xcode 12.3)
    • Xcode at /Applications/Xcode.app/Contents/Developer
    ! Flutter recommends a minimum Xcode version of 13.
      Download the latest version or update via the Mac App Store.
    • CocoaPods version 1.11.2

[✓] Chrome - develop for the web
    • Chrome at /Applications/Google Chrome.app/Contents/MacOS/Google Chrome

[✓] VS Code (version 1.62.0)
    • VS Code at /Applications/Visual Studio Code.app/Contents
    • Flutter extension version 3.21.0

[✓] Connected device (5 available)
    • SM G975F (mobile)       • RZ8M802WY0X • android-arm64   • Android 11 (API 30)
    • Darshan's iphone (mobile)  • 21150b119064aecc249dfcfe05e259197461ce23 •
      ios            • iOS 14.4.1 18D61
    • iPhone 12 Pro Max (mobile) • A5473606-0213-4FD8-BA16-553433949729     •
      ios            • com.apple.CoreSimulator.SimRuntime.iOS-14-3 (simulator)
    • macOS (desktop)            • macos                                    •
      darwin-x64     • Mac OS X 10.15.4 19E2269 darwin-x64
    • Chrome (web)               • chrome                                   •
      web-javascript • Google Chrome 98.0.4758.80

[✓] HTTP Host Availability
    • All required HTTP hosts are available

! Doctor found issues in 1 category.
  3. darshankawar
    added
    a: tests"flutter test", flutter_test, or one of our tests
    frameworkflutter/packages/flutter repository. See also f: labels.
    has reproducible stepsThe issue has been confirmed reproducible and is ready to work on
    team-frameworkOwned by Framework team
    found in release: 3.19Found to occur in 3.19
    found in release: 3.22Found to occur in 3.22
    and removed
    in triagePresently being triaged by the triage team
    on Apr 8, 2024
  4. goderbauer
    added
    P2Important issues not at the top of the work list
    triaged-frameworkTriaged by Framework team
    on Apr 9, 2024
  5. bleroux
    changed the title [-]LayoutBuilder's descentant widgets should not rebulid more than once in the same frame[/-] [+]LayoutBuilder's descendant widgets should not rebuild more than once in the same frame[/+] on Apr 10, 2024

  6. LongCatIsLooong commented on Apr 30, 2024

    @LongCatIsLooong
    LongCatIsLooong
    on Apr 30, 2024
    ContributorAuthor

    Another case of this issue:

    testWidgets('duplicate GlobalKey false positive', (WidgetTester tester) async {
  final widgetKey = GlobalKey(debugLabel: 'widget key');
  final widgetWithKey = Builder(builder: (context) {
    Directionality.of(context);
    return SizedBox(key: widgetKey);
  });

  await tester.pumpWidget(
    Directionality(
      textDirection: TextDirection.ltr,
      child: Row(
        children: [
          LayoutBuilder(
            builder: (context, constraints) => widgetWithKey,
          ),
        ],
      ),
    ),
  );

  await tester.pumpWidget(
    Directionality(
      textDirection: TextDirection.rtl,
      child: Row(
        children: [
          LayoutBuilder(
            builder: (context, constraints) => const Placeholder(),
          ),
          widgetWithKey,
        ],
      ),
    ),
  );
});

    The framework would incorrectly report that there were duplicate global keys:

    The following assertion was thrown while finalizing the widget tree:
    Duplicate GlobalKey detected in widget tree.

    because the widgetWithKey builder will run twice during the second pumpWidget.

  7. LongCatIsLooong
    self-assigned this
    on Apr 30, 2024

  8. chunhtai commented on Apr 30, 2024

    @chunhtai
    chunhtai
    on Apr 30, 2024
    Contributor

    I tried to handle cases where layoutbuilders are involved https://docs.google.com/document/d/15U1XDLrP-SXfgeu5DBBsA7MQuFpDUW005Y2ObwmYWIc/edit#heading=h.pub7jnop54q0

    looks like i missed some use cases?

  9. LongCatIsLooong commented on May 1, 2024

    @LongCatIsLooong
    LongCatIsLooong
    on May 1, 2024
    ContributorAuthor

    I tried to handle cases where layoutbuilders are involved https://docs.google.com/document/d/15U1XDLrP-SXfgeu5DBBsA7MQuFpDUW005Y2ObwmYWIc/edit#heading=h.pub7jnop54q0

    looks like i missed some use cases?

    I think in this case it's actually worse than an incorrect assert. The final widget tree is incorrect with the LayoutBuilder double rebuild. The example from #146379 (comment) generates the following widget tree:

          └Directionality(textDirection: rtl)
       └Row(direction: horizontal, mainAxisAlignment: start, crossAxisAlignment: center, dependencies: [Directionality], renderObject: RenderFlex#860c2)
        ├LayoutBuilder(renderObject: _RenderLayoutBuilder#d1a04 relayoutBoundary=up1)
        │└Placeholder
        │ └LimitedBox(maxWidth: 400.0, maxHeight: 400.0, renderObject: RenderLimitedBox#2a215 relayoutBoundary=up2)
        │  └CustomPaint(renderObject: RenderCustomPaint#d44b0 relayoutBoundary=up3)
        └Builder(dependencies: [Directionality])

    while the correct tree looks like this:

          └Directionality(textDirection: rtl)
       └Row(direction: horizontal, mainAxisAlignment: start, crossAxisAlignment: center, dependencies: [Directionality], renderObject: RenderFlex#0fc0c)
        ├LayoutBuilder(renderObject: _RenderLayoutBuilder#ac777 relayoutBoundary=up1)
        │└Placeholder
        │ └LimitedBox(maxWidth: 400.0, maxHeight: 400.0, renderObject: RenderLimitedBox#aca20 relayoutBoundary=up2)
        │  └CustomPaint(renderObject: RenderCustomPaint#09849 relayoutBoundary=up3)
        └Builder(dependencies: [Directionality])
         └SizedBox-[GlobalKey#0d1ba widget key](renderObject: RenderConstrainedBox#996dc relayoutBoundary=up1)

    The LayoutBuilder stole the keyed SizedBox during the first build, and the SizedBox was then unmounted.

  10. auto-submit
    closed this as completedin #147856on May 29, 2024
  11. auto-submit
    added 2 commits that reference this issue on May 29, 2024

    Prevent LayoutBuilder from rebuilding more than once (#147856)

    bafdb12

    Reverts "Prevent LayoutBuilder from rebuilding more than once (#147856)…

    ebc4143

  12. loic-sharma commented on May 30, 2024

    @loic-sharma
    loic-sharma
    on May 30, 2024
    Member

    @LongCatIsLooong, I'm reopening this as the fix was reverted: #149279

  13. loic-sharma
    reopened this on May 30, 2024
  14. victorsanni
    added 2 commits that reference this issue on May 31, 2024

    Prevent LayoutBuilder from rebuilding more than once (flutter#147856)

    f3da242

    Reverts "Prevent LayoutBuilder from rebuilding more than once (flutte…

    b6247aa
  15. LongCatIsLooong
    closed this as completedon Jun 5, 2024
  16. darshankawar
    added
    r: fixedIssue is closed as already fixed in a newer version
    on Jun 7, 2024

  17. gnprice commented on Jun 7, 2024

    @gnprice
    gnprice
    on Jun 7, 2024
    Member

    FTR, the reland appears to be #149303.

  18. github-actions commented on Jun 21, 2024

    @github-actions
    github-actionsbot
    on Jun 21, 2024 – with GitHub Actions

    This thread has been automatically locked since there has not been any recent activity after it was closed. If you are still experiencing a similar issue, please open a new bug, including the output of flutter doctor -v and a minimal reproduction of the issue.

  19. github-actions
    locked as resolved and limited conversation to collaborators on Jun 21, 2024
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P2Important issues not at the top of the work lista: tests"flutter test", flutter_test, or one of our testsfound in release: 3.19Found to occur in 3.19found in release: 3.22Found to occur in 3.22frameworkflutter/packages/flutter repository. See also f: labels.has reproducible stepsThe issue has been confirmed reproducible and is ready to work onr: fixedIssue is closed as already fixed in a newer versionteam-frameworkOwned by Framework teamtriaged-frameworkTriaged by Framework team

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