Destructuring $state array causes build to error

[WaltzingPenguin]

Describe the bug

Array destructuring from $state causes the build to error. This was working in 5.33.4 but is broken in the latest 5.33.14

Reproduction

Include the line let [level, custom] = $state([10, "Admin"]) in a Svelte file in your project and then attempt to build.

Or:

Repo: https://github.com/WaltzingPenguin/sveltekit-expected-ident
Install project and execute npm run build

Logs

PS C:\Users\Admin\Documents\Web Projects\sveltekit-unexpected-ident> npm run build

> [email protected] build
> vite build

vite v6.3.5 building SSR bundle for production...
✓ 15 modules transformed.
✗ Build failed in 69ms
error during build:
src/routes/unexpected-ident.svelte (2:10): Expected ident (Note that you need plugins to import files that are not JavaScript)
file: C:/Users/Admin/Documents/Web Projects/sveltekit-unexpected-ident/src/routes/unexpected-ident.svelte:2:10

1: <script lang="ts">
2: let [level, custom] = $state([10, "Admin"])
             ^
3: </script>

    at getRollupError (file:///C:/Users/Admin/Documents/Web%20Projects/sveltekit-unexpected-ident/node_modules/rollup/dist/es/shared/parseAst.js:401:41)
    at ParseError.initialise (file:///C:/Users/Admin/Documents/Web%20Projects/sveltekit-unexpected-ident/node_modules/rollup/dist/es/shared/node-entry.js:14293:28)
    at convertNode (file:///C:/Users/Admin/Documents/Web%20Projects/sveltekit-unexpected-ident/node_modules/rollup/dist/es/shared/node-entry.js:16197:10)
    at convertProgram (file:///C:/Users/Admin/Documents/Web%20Projects/sveltekit-unexpected-ident/node_modules/rollup/dist/es/shared/node-entry.js:15440:12)
    at Module.setSource (file:///C:/Users/Admin/Documents/Web%20Projects/sveltekit-unexpected-ident/node_modules/rollup/dist/es/shared/node-entry.js:17185:24)
    at async ModuleLoader.addModuleSource (file:///C:/Users/Admin/Documents/Web%20Projects/sveltekit-unexpected-ident/node_modules/rollup/dist/es/shared/node-entry.js:21187:13)

System Info

System:
    OS: Windows 11 10.0.26100
    CPU: (20) x64 13th Gen Intel(R) Core(TM) i5-13600KF
    Memory: 48.03 GB / 63.85 GB
  Binaries:
    Node: 22.13.1 - C:\Program Files\nodejs\node.EXE
    npm: 10.9.2 - C:\Program Files\nodejs\npm.CMD
    pnpm: 10.2.0 - ~\AppData\Local\pnpm\pnpm.CMD
  Browsers:
    Edge: Chromium (134.0.3124.83)
    Internet Explorer: 11.0.26100.1882

Severity

blocking an upgrade

[Ocean-OS]

It seems to work as expected here.

[MotionlessTrain]

It looks like a rollup error. But I don’t see how the JavaScript output from the svelte component could trigger that error

[paoloricciuti]

Something similar was fixed recently, which version of svelte are you on?

[Ocean-OS]

package.json says 5.33.14

[paoloricciuti]

Oh well... here's the generated server code lol

import * as $ from 'svelte/internal/server';

export default function App($$payload) {
	let tmp = [10, "Admin"],
		level = #[0],
		custom = #[1];

	$$payload.out += `<!---->${$.escape(level)}, ${$.escape(custom)}`;
}

[MotionlessTrain]

Whoops, I only checked the client code when I was curious whether I could find it 😄

[Ocean-OS]

Found the issue, don't know how this wasn't noticed before
https://github.com/sveltejs/svelte/blob/main/packages%2Fsvelte%2Fsrc%2Fcompiler%2Futils%2Fast.js#L341-L343