import scan merges script contexts causing duplicate variables and esbuild failure

[benmccann]

Describe the bug

Vite merges scripts together from .svelte files that the Svelte compiler treats as separate scripts:

vite/packages/vite/src/node/optimizer/scan.ts

Line 247 in 79c2a49

js += content + '\n'

Reproduction

npm init svelte@next my-app
cd my-app

Add to src/routes/index.svelte:

<script context="module">
let top;
</script>
<script>
export let top;
</script>

And then run npm run dev or npm run build

System Info

Vite 2.6.12

Used Package Manager

npm

Logs

html:src/routes/index.svelte:59:12: error: "top" has already been declared

Validations

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• The provided reproduction is a minimal reproducible example of the bug.

[benmccann]

One possible idea from Dominik:

You process it once and cache the module script in memory, add an import to it with a virtual id and return content from cache when that id is requested.

Prototype of that idea here: https://github.com/benmccann/vite/tree/context-module

It allows pre-bundling to succeed and SSR to succeed. However, on the client, it results in the error message Failed to fetch dynamically imported module: http://localhost:3000/src/routes/Example.svelte

I'm wondering if this is related or a separate bug. Do the results of scan.ts affect loading the .svelte file on the client? Maybe I broke something there somehow. I'm not quite sure how to debug

If I load that URL directly, it loads valid JS. Maybe it's not the correct URL format for Vite to interpret to load though?

[bluwy]

The idea looks fine to me. The error message does look off though, don't think that's related to your scanning changes, but a separate bug.

[benmccann]

Thanks for taking a look and suggesting that. I've confirmed it is an unrelated bug: sveltejs/kit#2699