svelte-check hangs on <script> tag with specific attributes

[shadow-identity]

Describe the bug

svelte-check hangs on svelte file containing <script> tag with particular set of attributes.

I noticed it because it was failing on this file.

Finally I was able to make a minimal reproduction.

Reproduction

1. Create a Svelte component file, or check out simplified reproduction repository, or check out existing one

    <script
        defer
        src='fds'
        on:load={() => {}}
    >
    </script>

2. Run svelte-check on it

Leading paces matters. Without spaces, it does not hang, but returns an error. But it doesn't change anything if the <script> is inside of another tag (still hangs).

! It is not reproduced in the reproduction repository. Only hanging is reproduced.

/Users/src/routes/Matomo.svelte:4:17
Error: Expected > (svelte)
    src='fds'
    on:load={() => {}}
>


/Users/src/routes/Matomo.svelte:4:17
Error: Expected > (js)
    src='fds'
    on:load={() => {}}
>

It does not hangs nor returns error if any of attributes are missing. So all the attributes matters

Expected behaviour

It should never hang, because it is bad for CI/CD, pre-commit hooks, editors etc.

System Info

• OS: macOS 14.4.1 (23E224), intel
• "svelte": "^4.2.15"
• "@sveltejs/adapter-static": "^3.0.1",
• "@sveltejs/kit": "^2.5.7",
• "@sveltejs/vite-plugin-svelte": "^3.1.0",
• "svelte-check": "^3.7.1",

Which package is the issue about?

No response

Additional Information, eg. Screenshots

I believe it is related to similar prettier-plugin-svelte issue

[jasonlyu123]

The hang is because of the regex for the script tag that is present in prettier-plugin-svelte, svelte and language-tools. It seems like the problem has to do with the multiple-line script tag. So until it's fixed, you can work around it by putting all the script tag attributes in one line.

[shadow-identity]

Nope, having it in one line causes the same issue:

/Users/pnedrigailov/workspace/location-insights/frontend/dashboard/src/routes/(root)/+layout.svelte:1:34
Error: Expected > (svelte)
<script defer src='' on:load={() => {}} lang="ts">
    import { setContext } from 'svelte'

[jasonlyu123]

The event won't work on top-level script tag so I think this is expected. The same error also exists in the svelte REPL.

[shadow-identity]

It fails on every level, not only on the top level. See https://gitlab.com/dexterlabs/dexlib/-/blob/f0679dc96428418e91c00ac879d15d762483ffed/packages/svelte-matomo/src/index.svelte for example.

[jasonlyu123]

I can't reproduce the parser error with the linked component in both Svelte 4 and 5. Please provide a reproduction repository.

[shadow-identity]

Sure. The reproduction repository can be found here: https://github.com/shadow-identity/sveltejs-language-tools-issues-2363
Check it out, install dependencies and do npm run check.
I also updated the description.

[shadow-identity]

Tho I was not able to reproduce the case with the error. It really appears if the <script> is on the top level, so not a bug (probably). Where is the regexp from your first comment is located? I can file a bug there.

[jasonlyu123]

A similar regex is in the svelte, prettier-plugin-svelte and language tools. There's already a related issue for Svelte core sveltejs/svelte#9564.