default exports not working on CJS + treeshake: true

[csantos1113]

    I'm having an issue after upgrading to `6.4.0` bundling to CJS.

Here is a simplified version of my react code:

// Component.tsx

import ReactSelect from 'react-select';

const Comp = (props) => {
  return <ReactSelect {...props} />
}

// tsup.config.ts

export default {
  bundle: true,
  clean: true,
  dts: true,
  format: ['cjs', 'esm'],
  minify: false,
  sourcemap: true,
  splitting: true,
  target: 'es2022',
  treeshake: 'smallest'

The generated CJS file with tsup v6.3.0 was working ✅

var ReactSelect = require('react-select');
var ReactSelect__default = /*#__PURE__*/_interopDefaultLegacy(ReactSelect);

var Comp = (props) => {
  return /* @__PURE__ */ jsxRuntime.jsx(ReactSelect__default["default"], { ...props });
}

The generated CJS file with tsup v6.4.0 isn't working ⚠️

var ReactSelect = require('react-select');
var Comp = (props) => {
  return /* @__PURE__ */ jsxRuntime.jsx(ReactSelect, { ...props });
}

Do you know if there is additional rollup configuration I need to pass to have rollup resolving default exports properly?

Originally posted by @csantos1113 in https://github.com/egoist/tsup/issues/749#issuecomment-1375931081

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[csantos1113]

Reading this piece of Rollup documentation: https://rollupjs.org/guide/en/#outputinterop it says:

Note that the default mode of "default" mimics NodeJS behavior and is different from TypeScript esModuleInterop. To get TypeScript's behavior, explicitly set the value to "auto". In the examples, we will be using the CommonJS format, but the choice of interop similarly applies to AMD, IIFE and UMD targets as well.

So I wonder if we should add interop: 'auto' here 👇 https://github.com/egoist/tsup/blob/31b2e7261fa84c41b0673c36bf7c7133dcbbda11/src/plugins/tree-shaking.ts#L46-L51

[github-actions[bot]]

:tada: This issue has been resolved in version 6.6.0 :tada:

The release is available on:

• npm package (@latest dist-tag)
• GitHub release

Your semantic-release bot :package::rocket: