bug: Unknown file extension `.json` in 6.x

[ihmpavel]

Hi, thank you for the library.

I came into an issue while updating to version 6.

Code (index.ts)

  const dir = './xyz'
  const realPath = relative(
    __dirname,
    fs.realpathSync(join(dir, 'file.json'))
  )
  const { default: content } = await import(realPath)
  console.log(content)

Working fine

• Version 5.x (latest 5.12.9)
• Build command tsup src/index.ts --format esm,cjs --dts

With version 6.x after reading release notes I though, that I need to add --shims (not mentioned in docs, only on release page) to build command (because we are using __dirname). Unfortunately that is not the case.

Does not work fine

• Version 6.x (any version)
• Build command tsup src/index.ts --shims --format esm,cjs --dts

Issue on version 6.x

TypeError [ERR_UNKNOWN_FILE_EXTENSION]: Unknown file extension ".json" for /Users/***********/xyz/file.json
    at new NodeError (node:internal/errors:371:5)
    at Object.getFileProtocolModuleFormat [as file:] (node:internal/modules/esm/get_format:87:11)
    at defaultGetFormat (node:internal/modules/esm/get_format:102:38)
    at defaultLoad (node:internal/modules/esm/load:21:14)
    at ESMLoader.load (node:internal/modules/esm/loader:359:26)
    at ESMLoader.moduleProvider (node:internal/modules/esm/loader:280:58)
    at new ModuleJob (node:internal/modules/esm/module_job:66:26)
    at ESMLoader.#createModuleJob (node:internal/modules/esm/loader:297:17)
    at ESMLoader.getModuleJob (node:internal/modules/esm/loader:261:34)
    at processTicksAndRejections (node:internal/process/task_queues:96:5) {
  code: 'ERR_UNKNOWN_FILE_EXTENSION'
}

Is there any way of fixing this?

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[egoist]

tsup won't bundle import(realPath) cause realPath is unknown at build time, you should manually read the file and JSON.parse it.

[egoist]

In v5 import() is compiled to require(), (the default target is node12) so require('xxx.json') worked, but now the target is node14, so import() is left as is, import('xxx.json') in Node.js runtime is not a thing.