Enum values from d.ts files cause exception when build with transpileOnly=true

[ArtemZag]

I tried to speed up build process. And transpileOnly=true works amazing!
Until I use any enum value in my code.

Example:
Definition file: definitions.d.ts

declare module MyModule {
  export const enum MyEnum {
    EnumValue1 = 0,
    EnumValue2 = 1
  }
}

TS file: example.ts

/// <reference path="./definitions.d.ts" />
console.log(MyModule.MyEnum.EnumValue1);

In runtime I get error: "MyModule is not defined"
Is there any way to force ts-loader NOT to ignore some specific *.d.ts files when I use transpileOnly=true? (something like transpileOnlyExcept...)

[wub]

Any news on this one?

[johnnyreilly]

We don't have a way to reproduce this issue and there's nothing we can look into at present...

[schmuli]

@johnnyreilly I just stumbled across this issue today, as we have just started using the transpileOnly option. In my case, we are using regular ES6 modules (imports and exports).

I have prepared a repro repo, please have a look: https://github.com/schmuli/ts-loader-enum

As I mention in the readme, I noticed that typescript will also throw an error when using isolatedModules, is this the same or a similar issue for ts-loader?

[johnnyreilly]

I think this comes down to transpileOnly not producing .d.ts files. As such it's probably expected behaviour. There's a good explanation here: TypeStrong/fork-ts-checker-webpack-plugin#49

There's also a suggested solution mentioned by @piotr-oles. All we need is someone to implement it 😉

FWIW I suspect it makes more sense for this to be implemented in ts-loader rather than the fork checker. Up until now the fork-ts-checker-webpack-plugin hasn't emitted anything whereas ts-loader has. I can imagine having an option that emits .d.ts when transpileMode is true

[schmuli]

I thought it was the .d.ts file, so I changed the file to a regular .ts file. However, now the const enum is still not being removed, and is included in the webpack output.

Again, this is probably a result of using transpileOnly, which is similar to isolatedModules. I will have a look in the TypeScript issues.

[schmuli]

Here is an (open) issue from TypeScript: microsoft/TypeScript#16671.

And another comment on isolatedModules: microsoft/TypeScript#10879 (comment)

[stale]

This issue has been automatically marked as stale because it has not had recent activity. It will be closed if no further activity occurs. Thank you for your contributions.

[dark-monst]

Currently have the same issue. Commenting for this not to be closed