svelte5: Snippet now causes type issues if being passed as prop

[duydang2311]

Describe the bug

Passing a snippet to a parameter of type Snippet will now cause type issues but renders just fine in runtime.

Type '() => ReturnType<import("svelte").Snippet>' is not assignable to type 'Snippet<[]>'.
  Type '{ '{@render ...} must be called with a Snippet': "import type { Snippet } from 'svelte'"; } & typeof SnippetReturn' is not assignable to type '{ '{@render ...} must be called with a Snippet': "import type { Snippet } from 'svelte'"; } & typeof SnippetReturn'. Two different types with this name exist, but they are unrelated.
    Type '{ '{@render ...} must be called with a Snippet': "import type { Snippet } from 'svelte'"; } & unique symbol' is not assignable to type 'unique symbol'

Reproduction

https://svelte-5-preview.vercel.app/#H4sIAAAAAAAACsVTTYvbMBD9K69qqROwHejRcUxL6a2Hsru31RaceJwIZEnVR9Jg_N-LZacJXQg9tTpJozdfb-b1rBWSHCuee6bqjljBPhnDUubPZny4I0lPLGVOB7sbLaXbWWF8xRX3ojPaenzWndGKlP-A1uoOSb66mvIpRLLmqlxdfVX_1ilhDHkcSEq9WA5clc7UqjppK5tyFe9c9asZN4xe5U2u2b7pY4ABqwrlmyyDaHHWASZ4-INwePjy7SuEwtHtdEM4CX_A0yNkrfah3hMc2SNZkKq3kpoU_kB2hEmJLWEkAsK5QA7xI8sqrmKi-XyfDldPIzRZLLGp8EA-2GgpJ5YWfCaTs2X-OJVeJRAOSnvUzol9LABeTzmTGVQ-v1RJzhUwxe-R9B8tqYYs8jwf0AXnx0p3tZTUTP3VmL2TApzNc4ph-8sPhnla84A4W2PA-4jS7QU19XG3zv9SUI6nk0Yj2pYsqSmUm1LFoY_LDPopnE-xjZtAZ9SWEJQlWXtqIqX_itSgxI9AcOduq-VdNv9AZlnFUtbpRrSCGlZ4G2hIf4v1Koe_0Gxc-Q1n3nF2q9_7LaxH5E4r59FfNIehuD6KG88N3hmrjVssX-n9Qu_stVgOrxt7GX4B-7tuupEEAAA=

Logs

No response

System Info

System:
    OS: Windows 11 10.0.22631
    CPU: (8) x64 Intel(R) Core(TM) i3-10100F CPU @ 3.60GHz
    Memory: 2.45 GB / 15.94 GB
  Binaries:
    Node: 22.5.1 - C:\Program Files\nodejs\node.EXE
    npm: 10.8.2 - C:\Program Files\nodejs\npm.CMD
    bun: 1.1.30 - ~\scoop\shims\bun.EXE
  Browsers:
    Edge: Chromium (129.0.2792.89)
    Internet Explorer: 11.0.22621.3527
  npmPackages:
    svelte: ^5.0.0-next.269 => 5.0.0-next.269

Severity

annoyance

[nmzein]

I cant seem to reproduce this error, have you checked that you're running the latest versions of the dependencies.

[duydang2311]

Yes, it is happening on [email protected] for me.

I'm not sure if snippet: Snippet is the correct declaration for snippet, but at least that's how it's done in Svelte 5 docs. It just works when I change it to snippet: () => ReturnType<Snippet> as the error shows.

I guess this is the way it should be done and the docs is a bit outdated?

[brunnerh]

Also cannot reproduce this. The main thing that needs to be up do date is your Svelte extension which runs the language server, transforms and checks the code.

[duydang2311]

Svelte extension is latest and I also tried downgrading to old versions from weeks ago, it still showing the error. I'm kinda confused what is happening but this seems like a problem on my end after all this. I'll try re-installing node modules and whatever I can.

Thanks for the confirmation!

[brunnerh]

You can also try running svelte-check, that way you can check the code independently of the IDE and maybe narrow it down a bit more.

[MrBns]

:-) what should I say. I am also getting this error.