fix: preset-env throws exception for export * as x

[liuxingbaoyu]

Q	A
Fixed Issues?	Fixes #16155
Patch: Bug Fix?
Major: Breaking Change?
Minor: New Feature?
Tests Added + Pass?	Yes
Documentation PR Link
Any Dependency Changes?
License	MIT

[babel-bot]

Build successful! You can test your changes in the REPL here: https://babeljs.io/repl/build/56104/

[liuxingbaoyu]

Because of its existence, it did not cause a more serious regression.
But I'm not sure if this PR is the best fix.

babel/packages/babel-preset-env/src/index.ts

Lines 407 to 418 in 3284897

	// If the caller does not support export-namespace-from, we forcefully add
	// the plugin to `includes`.
	// TODO(Babel 8): stop doing this, similarly to how we don't do this for any
	// other plugin. We can consider adding bundlers as targets in the future,
	// but we should not have a one-off special case for this plugin.
	if (
	optionsModules === "auto" &&
	!api.caller(supportsExportNamespaceFrom) &&
	!exclude.plugins.has("transform-export-namespace-from")
	) {
	include.plugins.add("transform-export-namespace-from");
	}

[nicolo-ribaudo]

The old error makes sense when one feature was standard and one a proposal. Now nobody even knows that export * as was not introduced together with ESM.

[JLHwung]

This would be not consistent with how we treat dynamic import() in the module transforms, the dynamic-import plugin is required if import() is seen in module transforms

babel/packages/babel-plugin-transform-modules-amd/src/index.ts

Line 92 in 665078b

if (!this.file.has("@babel/plugin-proposal-dynamic-import")) return;

I think the expected behaviour should be: let preset-env add module related transform plugins when modules is not false, and respect the compat-data only when module is false.

[liuxingbaoyu]

actions/download-artifact#249
I'm surprised it's been two weeks and it still hasn't been fixed.

[nicolo-ribaudo]

I'd like to release a patch once this is merged.

[preservance717]

Hi @liuxingbaoyu @JLHwung @nicolo-ribaudo
Could you help take a look the question when u are free,thx?

After the babel related dependencies in our project were upgraded from 7.23.7 to 7.23.8, the page could not work normally and the page prompted the error ES Modules may not assign module.exports or exports.*, Use ESM export syntax, instead: ./*/index.js.
Related babel configuration:

 presets: [
      [
        '@babel/preset-env',
        {
          useBuiltIns: 'usage',
          corejs: 3,
        },
      ],
      [
        '@babel/preset-react'
      ],
      ['@babel/preset-typescript'],
    ],
plugins: [***]

If I want the page to work fine, I need to use one of two following ways:

• add configuration: sourceType: "unambiguous", and the page will work normally.
• Or change the '@babel/preset-env' preset to

[
  '@babel/preset-env',
  {
    "targets": "defaults"
  },
]

What I'm curious about now is why 7.23.7 version doesn't need to add/update configurations, but 7.23.8 version needs to change these configurations. I feel that it is related to the three latest PR changes (#16181 #16201 #16199), but I can't find the specific point. Can you help me check it out? will appreciate it.

[liuxingbaoyu]

Only this PR is relevant between 7.23.7 and 7.23.8, but I don't know how it breaks your build.
Can you provide a repository to reproduce?

[preservance717]

Thanks for your quick reply, I can't reproduce it on the practice demo, but I will try it on serval times, if reproduced successfully, I will provide it.