Wildcard imports are getting removed with tree shaking

[msaehn]

Hi, I got another issue where tree shaking deletes code which is used.
This issue is similar to #969 and #844

I created an example repository: https://github.com/papierschiff/snowpack-bug

Steps to reproduce it:

1. clone example repository
2. npm install
3. npm run build
   You get the output: Generated an empty chunk: "@react-hook/resize-observer"

The issue is the following import:
import * as useResizeObserver from '@react-hook/resize-observer';

But it is working when I import it like:
import useResizeObserver from '@react-hook/resize-observer';

see example import: https://github.com/papierschiff/snowpack-bug/blob/master/src/App.jsx

[FredKSchott]

You cannot use a namespace as a function. When you do import * as useResizeObserver, useResizeObserver is guaranteed to be an object.

Because "@react-hook/resize-observer" is a common.js package, it will be automatically exported as the default export.

For these reasons, import useResizeObserver from '@react-hook/resize-observer'; is the only valid way to import this package.

[msaehn]

hi, thank you for your response. but why is it working when I disable the tree shaking?
My issue is, I can't change the way how the import is written.

[FredKSchott]

Hmm, I'm not sure.

You can't control the import? Hmm... I'm actually not sure what to do then. It's not valid ESM to use import * as useResizeObserver and then use that namespace as a function, which is a limitation of the browser and not Snowpack. I'd actually be surprised if this was ever working for that reason (with or without treeshaking).

If you can change the import to import useResizeObserver from ... then that's still your best option.