Comment by throwitaway1123

Yes, as you pointed out, not only can bundlers tree shake namespace imports, but they're literally used in the esbuild documentation to demonstrate the concept of tree shaking.

The issue you linked to is referring to the case in which you import a namespace object and then re-export it. Bundlers like webpack and rollup (which vite uses in production) can tree shake this pattern as well, but esbuild struggles with it.

If you're using esbuild instead of this:

  import * as someLibrary from "some-library"
  someLibrary.someFunction()
  export { someLibrary }

You can still do this:

  import * as someLibrary from "some-library"
  someLibrary.someFunction()
  export * from "some-library"
  export { default as someLibraryDefault } from "some-library"
  

Tree shaking works as expected for downstream packages using esbuild in the second case, which someone else in the linked issue pointed out: https://github.com/evanw/esbuild/issues/1420#issuecomment-96...