Dynamic imports are not tree-shaken

[fabiospampinato]

Describe the bug

Static imports are tree-shaken, so should statically analyzable dynamic imports.

Reproduction

https://github.com/vitejs/vite/files/10094628/repro.zip

Steps to reproduce

• npm i
• npm run build
• Look into the dist folder, and you'll see that not only the "visit" function is bundled when using dynamic imports.

System Info

System:
    OS: macOS 12.5.1
    CPU: (10) arm64 Apple M1 Max
    Memory: 981.67 MB / 32.00 GB
    Shell: 5.8.1 - /bin/zsh
  Binaries:
    Node: 18.12.0 - ~/.nvm/versions/node/v18.12.0/bin/node
    npm: 8.19.2 - ~/.nvm/versions/node/v18.12.0/bin/npm

Used Package Manager

npm

Logs

No response

Validations

• Follow our Code of Conduct
• Read the Contributing Guidelines.
• Read the docs.
• Check that there isn't already an issue that reports the same bug to avoid creating a duplicate.
• Make sure this is a Vite issue and not a framework-specific issue. For example, if it's a Vue SFC related bug, it should likely be reported to vuejs/core instead.
• Check that this is a concrete bug. For Q&A open a GitHub Discussion or join our Discord Chat Server.
• The provided reproduction is a minimal reproducible example of the bug.

[sapphi-red]

This is not supported by rollup (rollup/rollup#3417, rollup/rollup#3447) (repro with rollup@2.79.1, repro with rollup@3.4.0).

The workaround would be to create an facade module like:

// foo.js
import('./bar-facade').then(({ bar }) => bar())

// bar-facade.js
export { bar } from './bar'

// bar.js
export const bar = ''
export const bar1 = ''

[sapphi-red]

Closing as this is now supported by rollup 🎉 (repro with rollup@3.21.0)