Include corresponding values in d.ts for C-style enums

[remagpie]

Motivation

wasm_bindgen macro supports C-style enums. It supports specifying literal values for each enum variant, but it seems that those values are not included in the generated d.ts file. For example,

#[wasm_bindgen]
pub enum ErrorCode {
    FooError = 0,
    BarError = 2,
}

is converted to the following code:

export enum ErrorCode {
  FooError,
  BarError,
}

Specifying the actual values of enum lets us use more features in typescript, so it would be nice if the corresponding literal values are included in d.ts.

Proposed Solution

The ideal solution would give us the following typescript code:

export enum ErrorCode {
  FooError = 0,
  BarError = 2,
}

[Dollab]

👍 This is really important as otherwise it can lead to subtle bugs when using the literal value of the enum.

In particular, non initialized enum in the typescript declaration file generated by wasm_bindgen will be computed. This all prevents the use of the enum variants in type declarations.