[ddc] switch case doesn't match enum when enum comes from a different library and has a final field that's not initialized via constructor

[denniskaselow]

This is a very niche and unusual case with an easy workaround, but I still wanted to report it.

Running the following code prints this should NOT happen when compiled with ddc:

// main.dart
import 'package:switch_case_enum_bug/my_enum.dart';

void main() {
  final value = MyEnum.a;
  print(switch (value) {
    MyEnum.a => 'this should happen',
    _ => 'this should NOT happen',
  });
}

// my_enum.dart
enum MyEnum {
  a;
  final someText = 'Hello World';
}

It only happens if the enum is defined in a separate library (with main.dart in the web directory and my_enum.dart in the lib directory). The generated code looks like this:

  dart.defineLazy(CT, {
    get C0() {
      return C[0] = dart.const(Object.setPrototypeOf({
        [_Enum__name]: "a",
        [_Enum_index]: 0,
        someText: null
      }, my_enum.MyEnum.prototype));
    }
  });

someText: null seems to be the problem. It's correctly initialized to Hello World if the enum is in the same library or if it's initialized via constructor.

A simple workaround is to initialize the field in the constructor or turning it into a getter. (I've only run into this issue because my actual enum implements an interface that has a field that I'm not yet using)

tested with:
Dart SDK version: 3.7.0-309.0.dev (dev) (Tue Jan 7 20:06:23 2025 -0800) on "windows_x64"
Dart SDK version: 3.7.0-323.0.dev (dev) (Mon Jan 13 04:02:13 2025 -0800) on "windows_x64"