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Using build_runner

Inspect your lib/bridge_generated.dart and you will see that the definition of Platform has changed:

@freezed
sealed class Platform with _$Platform {
    const factory Platform.unknown() = Platform_Unknown;
    const factory Platform.android() = Platform_Android;
    const factory Platforn.ios() = Platform_Ios;
    const factory Platform.windows() = Platform_Windows;
    const factory Platform.unix() = Platform_Unix;
    const factory Platform.macOs(
        String field0,
    ) = Platform_MacOs;
    const factory Platform.wasm() = Platform_Wasm;
}

It is no longer a plain enum, but a full-blown enum class with variants! As it is right now, this code cannot compile yet since it is missing some components, namely the freezed library. freezed is a codegen library similar to those we've encountered thus far, but generates more Dart code instead. All such libraries perform their code generation upon invoking build_runner, i.e. when flutter pub run build_runner build is executed.

Regardless, to make this code compile again, we need to make a few changes:

  • Run the following commands to add the latest version of freezed:
flutter pub add -d build_runner
flutter pub add -d freezed
flutter pub add freezed_annotation
  • Update justfile to run build_runner after Rust codegen:
 gen:
     ..
     # Uncomment this line to invoke build_runner as well
-    # flutter pub run build_runner build
+    flutter pub run build_runner build

Now calling just will generate both the Rust bindings and the Dart library code.