fix: ESM and CJS type definitions conflict

[sentience]

The recent #1742 explicitly exports TypeScript type definitions from package.json:

  "exports": {
     ".": {
       "require": {
         "types": "./dist/index.d.ts",
         "default": "./dist/index.cjs"
       },
       "import": {
         "types": "./dist/index.d.ts",
         "default": "./dist/index.mjs"
       }
     },
     "./package.json": "./package.json"
   },

Unfortunately, as documented in the TypeScript Handbook, CommonJS (require) and ESM (import) module versions cannot share the same index.d.ts file:

It’s important to note that the CommonJS entrypoint and the ES module entrypoint each needs its own declaration file, even if the contents are the same between them. Every declaration file is interpreted either as a CommonJS module or as an ES module, based on its file extension and the "type" field of the package.json, and this detected module kind must match the module kind that Node will detect for the corresponding JavaScript file for type checking to be correct. Attempting to use a single .d.ts file to type both an ES module entrypoint and a CommonJS entrypoint will cause TypeScript to think only one of those entrypoints exists, causing compiler errors for users of the package.

I am seeing the compiler errors that this documentation warns of.

This issue appears to have been recently fixed in
the unbuild build tool that js-lingui depends upon (see issue unjs/unbuild#238 and fix unjs/unbuild#273), and that fix was released in unbuild 2.0.0-rc0.

This fix for detect-locale, therefore, is to upgrade to unbuild 2.0.0, and use the separate .d.cts and .d.mts type declaration files it outputs.

Note: This moves detect-locale onto a newer major version of unbuild than the other packages in this monorepo.
It may be preferred to upgrade them all,
but I am not familiar enough with the other packages to do this quickly.

Types of changes

• Bugfix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• Documentation update

Checklist

• I have read the CONTRIBUTING and CODE_OF_CONDUCT docs
• I have added tests that prove my fix is effective or that my feature works
• I have added necessary documentation (if appropriate)

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Name	Status	Preview	Comments	Updated (UTC)
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[github-actions]

size-limit report 📦

Path	Size
./packages/core/dist/index.mjs	2.76 KB (0%)
./packages/detect-locale/dist/index.mjs	721 B (0%)
./packages/react/dist/index.mjs	2.21 KB (0%)
./packages/remote-loader/dist/index.mjs	7.24 KB (0%)

[timofei-iatsenko]

Thanks for bringing this issue.

I kept track on unbuild, and even contributed in the discussion related to separate definitions for esm / cjs. It's good that they finally released a stable version.

It may be preferred to upgrade them all

Yes, it's better to update it monorepo-wide and apply the separate definitions for all packages. I will do that by myself.