[Bug]: `Source` type resolves to `any` under `moduleResolution: "nodenext"` due to unresolvable `../compiled/webpack-sources` import

[pikadun]

System Info

System:
OS: Linux 6.8 Ubuntu 24.04.3 LTS 24.04.3 LTS (Noble Numbat)
CPU: (2) arm64 unknown
Memory: 2.52 GB / 5.77 GB
Container: Yes
Shell: 5.2.21 - /bin/bash
Binaries:
Node: 24.13.0 - /usr/bin/node
npm: 11.6.2 - /usr/bin/npm
npmPackages:
@rspack/core: ^2.0.0-beta.5 => 2.0.0-beta.5

Details

When consuming @rspack/core types with moduleResolution: "nodenext" (or "node16"), the Source type used throughout the package (e.g. Compilation.assets, Compilation.getAsset()) silently degrades to any.

This happens because dist/Compilation.d.ts imports Source via a bare directory path:

import type { Source } from '../compiled/webpack-sources';

Under nodenext ESM resolution, TypeScript cannot resolve this path. The @rspack/core package has "type": "module", so dist/Compilation.d.ts is treated as ESM. In ESM mode, nodenext does not perform directory-to-package.json→types resolution for relative imports. The module fails to resolve, and Source falls back to any.

npx tsc --traceResolution confirms:

======== Resolving module '../compiled/webpack-sources' from 'node_modules/@rspack/core/dist/BuildInfo.d.ts'. ========
Resolution for module '../compiled/webpack-sources' was found in cache from location 'node_modules/@rspack/core/dist'.
======== Module name '../compiled/webpack-sources' was not resolved. ========

This affects all types that depend on Source, including:

• Compilation.assets → Record<string, any> instead of Record<string, Source>
• Compilation.getAsset() → Source field becomes any
• Compilation.emitAsset() / updateAsset() parameter types
• Assets type alias (Record<string, Source>)
• sources namespace re-export

Reproduce link

https://github.com/pikadun/rspack-source-type

Reproduce Steps

1. npm install
2. npm run test

[pikadun]

Root Cause

compiled/webpack-sources/package.json declares:

{
  "name": "webpack-sources",
  "types": "types.d.ts",
  "type": "commonjs"
}

Under nodenext ESM resolution, a bare directory relative import (../compiled/webpack-sources) does not trigger package.json → types lookup. TypeScript requires either:

1. An explicit file extension in the import (e.g. ../compiled/webpack-sources/types.d.ts), or
2. An exports field in the nested package.json that maps "." with a "types" condition

Since neither is present, the resolution fails.

The same issue affects other ../compiled/* imports in the package (e.g. @rspack/lite-tapable).