Rspack Bug: ExportedEnum Fails With Namespace Aliases

by SLV Team 54 views

Hey guys, let's dive into a frustrating bug I found while working with Rspack, specifically concerning the exportedEnum feature. This is a heads-up for anyone using Rspack who heavily relies on enums with namespace aliases. You might run into the same issue! I'll break down the problem, show you how to reproduce it, and hopefully, help you understand what's going on. This is super important because exportedEnum is a powerful feature for optimizing TypeScript code, and when it doesn't play nice with aliases, it can cause some headaches. So, let's get into it.

The Core of the Problem: exportedEnum and Namespaces

So, the main issue is that when you enable the exportedEnum feature in Rspack, it doesn't correctly handle enum types that use aliases with a namespace. This means that if you've got an enum, let's say TestEnum, and you've defined a namespace for it (like TestEnum with helper functions or additional properties), the exportedEnum feature seems to choke. This can cause unexpected behavior, compile-time errors, or even runtime issues. This really messes with the expected behavior of exportedEnum, which is designed to provide better type information and potentially optimize your code. Imagine having to refactor your code because of this, yikes! We all want our code to work as expected, right?

To make it clear, let's look at a code snippet. The setup is pretty standard, you've got your enum defined like so:

export enum TestEnum {
  TEST_1 = 'test',
}

Now, here's where the problem creeps in. Let's add a namespace to TestEnum to include some helper functions:

export namespace TestEnum {
  export const isTest = (value: TestEnum) => {
    return value === TestEnum.TEST_1;
  }
}

With exportedEnum enabled, this setup is expected to work flawlessly and preserve the type information and functionality of your enum, including the additional helpers defined in the namespace. However, the bug causes Rspack to misinterpret or mishandle the interplay between the enum and its namespace alias. The isTest function, which we expect to correctly check if a given value is TestEnum.TEST_1, might not work as intended. This can lead to bugs in your application. For example, if you rely on the isTest function in your logic and it fails, it can cause unexpected errors or incorrect behavior. So, to ensure your code is running as it should, you must be aware of the problem.

System Setup and Configuration

To understand the context better, here's a peek at the system information where this bug was observed. This information is crucial because it helps pinpoint the exact environment where the problem occurs. This information is key because it can help the developers determine if there are dependencies or configurations that impact the bug. The environment setup includes:

  • Operating System: macOS 13.6
  • CPU: 10-core Apple M1 Pro
  • Memory: 16GB
  • Node.js: v18.20.4
  • Yarn: 1.22.19
  • npm: 10.7.0
  • pnpm: 8.15.8
  • Rspack Version: (Implied, but it's important to test with the latest versions to see if the issue persists.)

The configuration in rspack.config.js looks something like this:

export default defineConfig({
  tools: {
    swc: {
      rspackExperiments: {
        collectTypeScriptInfo: {
          exportedEnum: true,
        }
      }
    }
  }
});

In this configuration, the exportedEnum feature is enabled within the rspackExperiments section of the SWC tool. This setup is pretty standard, but the specific versions of the tools and libraries are essential for reproduction. It helps developers to create a consistent environment for replicating the issue, which assists them in debugging and finding a solution.

Steps to Reproduce the Bug

Reproducing this bug is pretty straightforward. I've even provided a handy reproduction link to make it even easier. Here's a step-by-step guide:

  1. Clone the Repository: Start by cloning the provided repository, which contains the exact code that reproduces the issue. You can grab the code from this GitHub repository. This ensures that you have the same starting point as me, so you can follow along.

  2. Install Dependencies: Navigate to the project directory in your terminal and run your preferred package manager command (e.g., npm install, yarn install, or pnpm install) to install all the necessary dependencies. This will ensure that all the required packages are available for the project to run.

  3. Run the Build Process: Execute the build command. This usually involves a command like rspack build, but check the package.json file for the exact command. The build process should trigger Rspack to compile the TypeScript code. The expected behavior is that the compilation completes without errors, but with the bug, you may see compilation errors, or the generated code may behave incorrectly.

  4. Observe the Output: Carefully review the output of the build process and test the generated code. Pay close attention to how the TestEnum and its isTest function behave. If the exportedEnum feature fails to correctly handle the namespace alias, the output or the runtime behavior will expose the problem.

These steps will help you replicate the bug and see how the exportedEnum feature fails. By following these steps, you will be able to see the bug in action and understand its impact on your code.

Potential Workarounds (If You Must)

Alright, guys, since the exportedEnum feature has a bit of a hiccup, here are some workarounds you can use while the issue is being resolved. Remember, these are temporary fixes, so always keep an eye out for updates and patches. These workarounds are not ideal, but they can help you maintain functionality while you're waiting for a fix. Here are some options:

  1. Avoid Namespaces for Enums: One of the simplest workarounds is to ditch the namespace altogether. Instead of using a namespace to add helper functions or properties to your enum, you can define these functions separately. Keep the helper functions outside of the TestEnum definition. While this may mean a bit more code, it should bypass the bug.
export enum TestEnum {
  TEST_1 = 'test',
}

export const isTest = (value: TestEnum) => {
  return value === TestEnum.TEST_1;
}
  1. Manual Type Definitions: Another potential approach is to manually create type definitions for your enums. This is particularly useful if you need to provide more control or avoid the limitations of the exportedEnum feature. This might involve creating a separate .d.ts file that defines the types and interfaces related to your enum. This gives you more control over how the types are defined and used.
// test-enum.d.ts
declare enum TestEnum {
  TEST_1 = 'test',
}

declare namespace TestEnum {
  function isTest(value: TestEnum): boolean;
}

export { TestEnum };
  1. Alternative Code Structure: Consider restructuring your code to minimize the impact of the bug. This could involve refactoring the way you use enums and namespaces to bypass the problem. For example, instead of using namespaces, you could use a class with static methods. While this might alter the design of your code, it may provide a viable workaround.

Conclusion

So, there you have it, folks! We've uncovered a bug with Rspack's exportedEnum feature when dealing with enums and namespace aliases. It's a bummer, but by understanding the problem, reproducing it, and finding some workarounds, we can at least keep our projects running smoothly until a fix comes along. Remember to stay updated with Rspack releases and check the issue tracker for any progress on this front. Hopefully, this helps you avoid some headaches and keep your projects on track. Happy coding!