Export * should allow named export overrides

[lexanth]

Describe the bug
When you do export * from 'x' and override something in * with a named export, according to the spec the named export should override the version from *. This pattern is recommended in e.g. https://testing-library.com/docs/react-testing-library/setup

Input code

import { customRender } from './customRender';

// re-export everything
export * from '@testing-library/react';

// override render method
export { customRender as render };

Config

{
  "sourceMaps": true,
  "jsc": {
    "parser": {
      "syntax": "typescript",
      "tsx": true,
      "dynamicImport": true
    },
    "transform": {
      "react": {
        "runtime": "automatic",
        "refresh": true
      },
      "hidden": {
        "jest": true
      }
    }
  },
  "module": {
    "type": "commonjs"
  },
  "env": {
    "coreJs": 3,
    "mode": "usage"
  }
}

Expected behavior
The transpilation should respect the behaviour that the named exports can override the wildcard exports.
e.g. Babel REPL generates the _exportNames and then excludes those when defining the wildcard export.

Other refs:

• System transformer should respect export * spec order (T6967) babel/babel#3986
• https://262.ecma-international.org/6.0/#sec-getexportednames
• https://stackoverflow.com/questions/34745110/es2015-re-export-module-and-override-single-export-function-of-the-re-exported-m

Version
The version of @swc/core: 1.2.55

Additional context
Workaround is to not depend on this behaviour

import * as rtl from '@testing-library/react';
import { customRender } from './customRender';

module.exports = {
  ...rtl,
  userEvent,
  render: customRender,
};

[atsikov]

Another case is that star exports should not override named exports
Such module should not export render from testing-library

export { customRender as render } from './customRender';

// re-export everything, but keep named 'render' exported above
export * from '@testing-library/react';

[lexanth]

@kdy1 This isn't quite fixed.

The code as currently output still gives a runtime error if the re-export is different from the initial export (which is the case in the example above - the aim is to override render with our custom version).

In your test (https://github.com/swc-project/swc/pull/1909/files#diff-b558773d8ee3e958908d1bdf859f470eabcd8ff82aee06841982ddcdcb6b11a2) it only checks if there is an existing export of that name with the same thing being exported (if (key in exports && exports[key] === _react[key]) return;).

In the babel output (REPL), it also tracks the list of named exports to not override

var _exportNames = {
  render: true
};

Object.keys(_react).forEach(function (key) {
  if (key === "default" || key === "__esModule") return;
  if (Object.prototype.hasOwnProperty.call(_exportNames, key)) return; // <-- This check is missing in the swc output
  if (key in exports && exports[key] === _react[key]) return;
  Object.defineProperty(exports, key, {
    enumerable: true,
    get: function () {
      return _react[key];
    }
  });
});

Without this check, at runtime you get an error from not being able to redefine the property (TypeError: Cannot redefine property: render)

[lexanth]

@kdy1 Can you reopen this, or would you like a new issue?

[kdy1]

I prefer a new issue, would you open one?

[lexanth]

Raised #2101 for this

[swc-bot]

This closed issue has been automatically locked because it had no new activity for a month. If you are running into a similar issue, please create a new issue with the steps to reproduce. Thank you.