add extensions to import specifier in dts files

[YiCChi]

I'm shipping a dual package using the config like

import { defineConfig } from '@rslib/core'
import type { LibConfig } from '@rslib/core';

export default defineConfig({
  lib: (['esm', 'cjs'] as const).map<LibConfig>(format => ({
    format,
    bundle: true,
    syntax: 'es2022',
    dts: {
      bundle: false,
    },
    outBase: 'src',
  })),
  source: {
    tsconfigPath: './tsconfig.json',
  },
  output: {
    cleanDistPath: true,
    sourceMap: true,
    target: 'node',
  }
})

with package.json in

{
  "types": "module"
}

and tsonfig in

{
  "compilerOptions": {
    "module": "esnext"
    "moduleResolution": "bundler"
  }
}

Found extensions is not be added according to the format

// foo.d.cts
export interface Foo {}

// index.d.cts
import { Foo } from './foo'
// not import { Foo } from './foo.cjs'

which causes a issue when consuming the package with tsconfig(>=5.8) with

{
  "compilerOptions": {
    "module": "nodenext"
    "moduleResolution": "nodenext"
  }
}

nodejs forces extensions for esm, so when tsc tries to resolve import ./foo, it can not resolve it successfully.

There are several answers for this issue I can do buy myself:

• config types to commonjs
• bundle dts files
• patch dts files after rslib building
• consume the package with { "moduleResolution": "bundler" }

But is there any offically solutions from rslib? thx

[Timeless0911]

Set redirect.dts.extension to true.

[YiCChi]

Thank u very much! Everything works fine now!
IMO, when the types is module, we can make the default value of redirect.dts.extension true, which is reasonable

[Timeless0911]

The default value based on "skipLibCheck": true in tsconfig.json which should be the default behaviour when you consume this package.

[Timeless0911]

We don't want to change the default for the rare case of nodenext, and IMO it's better to use bundler.