💡 RFC: Support Svelte 4

[ghostdevv]

Background & Motivation

Svelte 4 was released today so would be great to support it, unfortunately it doesn't seem language tools does currently. Sent a draft PR to astro to work on supporting it in the code there withastro/astro#7454. A list of breaking changes can be found here, but specifically I think we need to worry about:

breaking: Minimum supported TypeScript version is now TypeScript 5 (it will likely work with lower versions, but we make no guarantees about that) (sveltejs/svelte#8488)

breaking: Deprecate SvelteComponentTyped in favor of SvelteComponent (sveltejs/svelte#8512)

There may be more but I haven't looked at the implementation here. Happy to try and work on a pr at the end of this week if no one else wants to pick it up (may take some time to figure out as I am unfamiliar with the codebase).

Proposed Solution

n/a

Detailed Design

No response

Help make it happen!

• I am willing to submit a PR to implement this change.
• I am willing to submit a PR to implement this change, but would need some guidance.
• I am not willing to submit a PR to implement this change.

[bluwy]

Can you explain how language-tools isn't working with Svelte 4? It's working fine for me.

[Princesseuh]

Yeah, since we updated to the latest version of svelte2tsx some time ago, it should already be working as far as I know. Either way, the code to support this doesn't actually live in this repo, it's in the Svelte integration

[ghostdevv]

Nevermind it's working for me now 🙏