fix(es/module): Improve compatibility with cjs-module-lexer

[magic-akari]

Description:

Support reexport by emitting TS __export function call.

BREAKING CHANGE:

Related issue (if exists):

[kdy1]

Why is this required? Do you have any real-world usecase related to this?

[magic-akari]

Sometimes you need CommonJS while allowing them to be imported into node esm.
Node supports interoperability features by detecting CJS exports through the cjs-module-lexer library.

• Converted CommonJS cannot be imported using native ESM #5084 can be considered a use case.

---

There are two issues about compatibility with cjs-module-lexer that need to be fixed now.

1. reexport

The following code will output app page in native esm.
The page is reexport from page.js to app.js.

// page.js
export const page = "page";

// app.js
export * from "./page.js";

export const app = "app";

// index.js
import { app, page } from "./app.js";

console.log(app, page);

When compiling app.js and page.js into CommonJS, we expect the same result.
Therefore, we must tell node that we have re-export the page.js from app.js

We emit 0 && __export(require("foo")) to hint we reexport "foo".

This is similar to the way used by esbuild.

• Feature request: deep analysed annotations for cjs -> esm evanw/esbuild#2486 (comment)

---

2. arrow getter

Take the same example as above, we will get the following transformed code.

Object.defineProperty(exports, "page", {
    enumerable: true,
    get: ()=>page
});

Once cjs-module-lexer detects the page, but not in the format it expects,
cjs-module-lexer adds it to unsafe getter export and never exports it.

https://github.com/nodejs/cjs-module-lexer/blob/4641ae5419634deeefa41f943080f2eb7b2c925e/src/lexer.c#L442-L444
https://github.com/nodejs/cjs-module-lexer/blob/4641ae5419634deeefa41f943080f2eb7b2c925e/src/lexer.js#L31-L35

• I tried to add support for arrow getters feat: Support arrow getter in Object.defineProperty nodejs/cjs-module-lexer#74 , but it does not accept feature additions at this point

We need to change the output to a method/function getter until cjs-module-lexer supports arrow getters.

[kdy1]

It makes sense, thanks!

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swc-bump:

• swc_ecma_transforms_module

[swc-bot]

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