Support TypeScript 5.2 `using` Declarations and Explicit Resource Management in`.svelte` files

[TimoWilhelm]

Describe the problem

TypeScript 5.2 adds support for the upcoming Explicit Resource Management feature in ECMAScript.
However, using that syntax in .svelte files with <script lang="ts"> currently throws a svelte(js_parse_error).

As a workaround, the using declarations can be used in a neighboring .ts file that is imported by the .svelte file.

Describe the proposed solution

It would be nice if using declarations would be supported directly in .svelte files using lang="ts".

Importance

would make my life easier

[Ocean-OS]

I'm not sure why, but it appears that the Svelte compiler doesn't use the actual TypeScript compiler, but just removes the TS AST nodes using Acorn.
Perhaps the TypeScript compiler could be used instead? This would also mean we wouldn't have to worry about updating the node removal script whenever a new feature is added to TypeScript.

[jasonlyu123]

Yes. As mentioned, The built-in TypeScript support only stripping types. And does not handle syntaxes that need transformation. This includes upcoming ECMA script features like using. You can see the documentation here for the explanation and instructions on configuring a preprocessor to handle things that need transformation.

https://svelte.dev/docs/svelte/typescript#script-lang-ts

[TimoWilhelm]

Thanks @jasonlyu123, I appreciate the explanation! I must have missed that part of the docs.