Repository: flutter
Issue: ListView crashes the app with really large semanticChildCount (1000000000000)
Labels: framework,engine,a: accessibility,f: scrolling,has reproducible steps,P2,found in release: 3.7,found in release: 3.8,team-engine,triaged-engine

ListView crashes the app with really large semanticChildCount (1000000000000) with message "Semantics update contained scrollChildren but did not have childrenInHitTestOrder"

i know someone may ask for use case - i have an infinitely slowly scrolling list of automatically generated items and that's an easy way to get this wokring

if you try to lower this amount (did not measure exactly by what amount), the reproducible will stop crashing - for instance 1, 2, ...., 100000 etc. work fine

this happens on approximately 20% devices that we test our app on (it's already in production)

known devices that have this crash
* Samsung Galaxy S20 Android 11 ONE UI 3.0 and 3.1
* Samsung Galaxy S10 Plus
* Samsung Galaxy S10E
* ONE PLUS 6T
* Xiaomi Poco X3
* iPhone SE (not sure exactly which)
* Xiaomi Redmi Note 7 (not actually sure)
* Simulator iPhone SE (2nd generation) iOS 13.7

devices that had no problem
* Samsung Galaxy A50 (2019)
* Xiaomi Redmi Note 5 Android 9
* Xiaomi Redmi Note 8 pro
* iPhone 7 iOS 14.3

reproducible with logs are available here
https://github.com/nt4f04unds-archive/issues/tree/flutter_76640

note: i started expriencing this back on version 1.24 https://github.com/flutter/flutter/commit/183f0e797a3bf8aa1b35b650150f7522d5d10377, upgrading to master did not help

<details>
  <summary>flutter doctor -v (mac)</summary>

```
[✓] Flutter (Channel texture_buildable, 1.27.0-2.0.pre.100, on Mac OS X 10.15.2 19C57 darwin-x64, locale ru-RU)
    • Flutter version 1.27.0-2.0.pre.100 at /Users/danya/dev/src/flutter
    • Framework revision 76080cd46c (2 days ago), 2021-02-21 18:22:32 +0300
    • Engine revision 1d537824d6
    • Dart version 2.13.0 (build 2.13.0-30.0.dev)

[✗] Android toolchain - develop for Android devices
    ✗ Unable to locate Android SDK.
      Install Android Studio from: https://developer.android.com/studio/index.html
      On first launch it will assist you in installing the Android SDK components.
      (or visit https://flutter.dev/docs/get-started/install/macos#android-setup for detailed instructions).
      If the Android SDK has been installed to a custom location, please use
      `flutter config --android-sdk` to update to that location.


[!] Xcode - develop for iOS and macOS
    • Xcode at /Applications/Xcode.app/Contents/Developer
    • Xcode 11.7, Build version 11E801a
    ! Xcode 11.7.0 out of date (12.0.1 is recommended).
      Download the latest version or update via the Mac App Store.
    • CocoaPods version 1.10.0

[✓] Chrome - develop for the web
    • Chrome at /Applications/Google Chrome.app/Contents/MacOS/Google Chrome

[!] Android Studio (not installed)
    • Android Studio not found; download from https://developer.android.com/studio/index.html
      (or visit https://flutter.dev/docs/get-started/install/macos#android-setup for detailed instructions).

[✓] VS Code (version 1.53.2)
    • VS Code at /Applications/Visual Studio Code.app/Contents
    • Flutter extension version 3.19.0

[✓] Connected device (2 available)
    • iPhone SE (2nd generation) (mobile) • C8B744A0-7C40-4310-A011-C68D242FCD56 • ios            • com.apple.CoreSimulator.SimRuntime.iOS-13-7 (simulator)
    • Chrome (web)                        • chrome                               • web-javascript • Google Chrome 88.0.4324.192

! Doctor found issues in 3 categories.
```
</details>






<details>
  <summary>flutter doctor -v (windows)</summary>

```
[✓] Flutter (Channel texture_buildable, 1.27.0-2.0.pre.100, on Microsoft Windows [Version 10.0.19041.804], locale ru-RU)
    • Flutter version 1.27.0-2.0.pre.100 at c:\dev\src\flutter
    • Framework revision 76080cd46c (2 days ago), 2021-02-21 18:22:32 +0300
    • Engine revision 1d537824d6
    • Dart version 2.13.0 (build 2.13.0-30.0.dev)

[✓] Android toolchain - develop for Android devices (Android SDK version 30.0.2)
    • Android SDK at C:\Users\danya\AppData\Local\Android\sdk
    • Platform android-30, build-tools 30.0.2
    • Java binary at: C:\Program Files\Android\Android Studio\jre\bin\java
    • Java version OpenJDK Runtime Environment (build 1.8.0_242-release-1644-b01)
    • All Android licenses accepted.

[✓] Chrome - develop for the web
    • Chrome at C:\Program Files\Google\Chrome\Application\chrome.exe

[!] Visual Studio - develop for Windows (Visual Studio Community 2019 16.7.7)
    • Visual Studio at C:\Program Files (x86)\Microsoft Visual Studio\2019\Community
    • Visual Studio Community 2019 version 16.7.30621.155
    • Windows 10 SDK version 10.0.18362.0
    ✗ Visual Studio is missing necessary components. Please re-run the Visual Studio installer for the "Desktop development with C++" workload, and include these components:
        MSVC v142 - VS 2019 C++ x64/x86 build tools
         - If there are multiple build tool versions available, install the latest
        C++ CMake tools for Windows
        Windows 10 SDK

[✓] Android Studio (version 4.0)
    • Android Studio at C:\Program Files\Android\Android Studio
    • Flutter plugin version 50.0.1
    • Dart plugin version 193.7547
    • Java version OpenJDK Runtime Environment (build 1.8.0_242-release-1644-b01)

[✓] VS Code (version 1.53.2)
    • VS Code at C:\Users\danya\AppData\Local\Programs\Microsoft VS Code
    • Flutter extension version 3.19.0

[✓] Connected device (4 available)
    • Redmi Note 5 (mobile) • 40c9f14 • android-arm64  • Android 9 (API 28)
    • Windows (desktop)     • windows • windows-x64    • Microsoft Windows [Version 10.0.19041.804]
    • Chrome (web)          • chrome  • web-javascript • Google Chrome 88.0.4324.182
    • Edge (web)            • edge    • web-javascript • Microsoft Edge 88.0.705.68

! Doctor found issues in 1 category.
```
</details>