fix: correct default CJS exports

[userquin]

We should add exports to ESMExport interface in mlly, missing in dts, that's why I added the regex to extract the exports (upps, it is on NamedExport type):

{
  type: 'default',
  exports: ' type X, sum as default',
  specifier: undefined,
  code: 'export { type X, sum as default }',
  start: 87,
  end: 120,
  names: [ 'default' ],
  name: 'default',
  _type: 'named'
}

resolves #474

[pi0]

Sorry for late review dear @userquin.

Do you think you can add some unit tests for fixCJSExportTypePlugin? 🙏🏼 Since we are forking away from tsup implementation, it would be nice to have them in place to both prevent regressions and clearly test desired behaviors.

[userquin]

Do you think you can add some unit tests for fixCJSExportTypePlugin? 🙏🏼 Since we are forking away from tsup implementation, it would be nice to have them in place to both prevent regressions and clearly test desired behaviors.

To test the cjs types we can:

• add attw (will check the new fixtures) after the test: maybe using pnpm exec attw --pack
• add some small parsing via mlly and/or use d.ts and d.cts file snapshots (rn on my local using file snapshots)

I'm going to create a new repo to test the same fixtures using tsup (will fail for mixed declarations) and pkgroll (using import + require package exports here to allow re-use them in pkgroll).

[userquin]

@pi0 @danielroe

When all remaining exports (from the default export) only contains types (export { type A, type B }) the export contining the default is replaced by export type { A, B }. Check test/cjs-types-fixture/mixed-declarations/index.ts in this PR and the dist folder.

When re-exporting types from another import, there is no an easy way to know if the export is a type, and so when re-exporting exports, the export contining the default will not be changed. Check test/cjs-types-fixture/reexport-types/index.ts in this PR and the dist folder.

screenshot with generated d.ts files

[userquin]

With last commit in the re-export fixture:

[pi0]

Nice work @userquin. I'm wondering if you would be interested in maintaining it as an external/shared library now. (that converts .d.mts to .d.cts) -- it might be usable to unbuild and wider ecosystem.

[userquin]

Good idea, maybe we can add it here to the unjs ecosystem... I need to find some free time, too busy at work.