None of the patterns in the switch expression the matched after hot-reload

[petrnymsa]

Issue originally discussed on X (Twitter) with @mraleph.

Example project with a reproducible issue is originally stripped down version of our large project. I tried to minimize code to absolute minimum with some files which I believe are interesting and related to this issues.

What is happening?

Project is monorepo based application. Application is in apps folder and there is also core packages containing some "core" domain types.

We have enhanced enum ModuleType in "core" package. This enum describes available module of app (doesn't really matter for issue]. In app there is module_type_extension - a extension on ModuleType with simple switch expression returning some value based on ModuleType's value (for example path to icon).

After hot-reload sometimes issue appears:

None of the patterns in the switch expression the matched input value. See https://github.com/dart-lang/language/issues/3488 for details

but I don't understand why.

Some noticeable things

• issues is gone if we remove "BlocBuilder" (Flutter_Bloc) from home_page
• issue is gone if I completely remove apps/patterns_repro/lib/shared/widgets/dialogs/action/action_dialog.dart - this file is not used by home_page and related widgets BUT still somehow affects.

What I suspect: Issues seems to be related somehow to "barell" files and cyclic imports and exports. But my knowledge is falling behind to understand it.

How to repro step by step

• Run project on Android or iOS (emulator or rea device, should not matter)
• Change value of height on line 9 in apps/patterns_repro/lib/modules/home/widgets/enabled_modules_view.dart. (Or just anything there to invoke hot reload)
• Notice that mentioned issue appears

However like I said before

• Remove action_dialog.dart
• Uncomment lines 23 - 27 in home_page.dart returning EnabledModulesView directly. Issues seems to be gone no matter how ModyleType type is imported.

Dart and Flutter versions

Flutter 3.19.4 • channel stable • https://github.com/flutter/flutter.git
Framework • revision 68bfaea224 (12 days ago) • 2024-03-20 15:36:31 -0700
Engine • revision a5c24f538d
Tools • Dart 3.3.2 • DevTools 2.31.1

NOTE: Tested on different machines with Windows and MacOS.

Link to project: https://github.com/petrnymsa/dart-pattern-none-issue

[a-siva]

@petrnymsa There doesn't seem to be any licensing information associated with the code you provided for reproduction,, would it be possible to extract a reproduction into a simpler test case and post it here or add an open source license to your code that permits us to use the reproduction you have.

[petrnymsa]

@petrnymsa There doesn't seem to be any licensing information associated with the code you provided for reproduction,, would it be possible to extract a reproduction into a simpler test case and post it here or add an open source license to your code that permits us to use the reproduction you have.

Added LICENSE - MIT. Code is similar to minimal version from our, private project, but classes are renamed and simplified.