SWC Compress + Svelte = Error

[rikschennink]

Describe the bug

I don't know wether this problem originates in Svelte or in SWC, I lean towards SWC.

When I enable compress in the .swcrc config and then compress a Svelte built target the resulting file will throw an error when loaded in a browser.

I've set up a repository here: https://github.com/rikschennink/swc-svelte-problem

I ran into this because NextJS has enabled SWC to compress JS and since that time my Svelte based library can no longer be used with NextJS unless NextJS is configured to use Terser as JS compressor.

Input code

No response

Config

{
    "jsc": {
        "minify": {
            "compress": true, // set to false and it no longer errors
            "mangle": false
        }
    }
}

Playground link

No response

Expected behavior

It should work with and without compress enabled

Actual behavior

When compress is enabled the Svelte app no longer loads and throws the following error:

Uncaught TypeError: Cannot read properties of undefined (reading 'context')
    at I (test-swc.js:197:49)
    at new ft (test-swc.js:336:43)
    at swc.html:18:13

This error is thrown because current_component.$$ (Svelte specific) is somehow missing.

We can circumvent this by passing context: [] to the App constructor but now the error will be thrown on the App child component.

Version

1.3.25

Additional context

No response

[kdy1]

This is bug of swc

[rikschennink]

@kdy1 But what is it caused by, as-in what's it doing wrong, eliminating too much code?

[kdy1]

I don't know. I didn't investigate it yet

[rikschennink]

Ah okay, it seemed you knew because of the fast reply. 👍

[rikschennink]

🙏 Waw that was fast. Fingers crossed NextJS pulls this in asap.

[swc-bot]

This closed issue has been automatically locked because it had no new activity for a month. If you are running into a similar issue, please create a new issue with the steps to reproduce. Thank you.