Rolldown doesn't support `output.file` option

[kazupon]

reproduction repo

https://github.com/kazupon/rolldown-output-repro1

background

I noticed on #610

reproduction step

npm install

npm run build

tree -L 2
.
├── README.md
├── app.js
├── dist
│   ├── app.js
│   └── app.js.map
├── node_modules
│   ├── @rolldown
│   ├── @rollup
│   ├── @types
│   ├── fsevents
│   └── rollup
├── package-lock.json
├── package.json
├── rolldown.js
├── rollup.js
└── rollup_build
    ├── rollup.js
    └── rollup.js.map

9 directories, 10 files

rolldown write output option:

import { rolldown } from '@rolldown/node'

const bundle = await rolldown({
  input: 'app.js',
})

await bundle.write({
  format: 'esm',
  sourcemap: true,
  file: 'rolldown_build/rolldown.js'
})

rolldown cannot output to 'rolldown_build/rolldown.js' with file option.

rollup can ouput with file option.

rolldown write should have the same result as rollup.

[kazupon]

Ah, I see, the Rust side write does not receive output otpions from the JS side, it writes with the outputoptions passed to the Bundler when it initializes. https://github.com/rolldown/rolldown/blob/ec85051013b58b31abbb92e50472a9b1e476e321/crates/rolldown_binding/src/bundler.rs#L19-L41

If we pass output options to write, then we have to test the performance ((de)serialize).

[hyf0]

@kazupon

the Rust side write does not receive output otpions from the JS side

Nope. It does take the output options from js side, which is the options that passed from write or generate. I'm not sure the problem. But it probably due to we haven't support output.file option.

You should be able to use output.entryFileName: 'rolldown_build/rolldown.js' to do this. Or output.dir: 'rolldown_build' with output.entryFileName: 'rolldown.js'.

Notice that this only works out in single entry.

You see the functionality of output.file could be done with other options. I personally feel it's kind of overengineering. Let me talk with team about how we handle these kind of options.

[sapphi-red]

FWIW Vite does not support output.file as we generate multiple files. https://github.com/vitejs/vite/issues/11096#issuecomment-1333878325, https://github.com/vitejs/vite/pull/14909