typescript-eslint's "no any" rules don't work with inferred function types from sveltekit

[DetachHead]

Before You File a Bug Report Please Confirm You Have Done The Following...

• I have tried restarting my IDE and the issue persists.
• I have updated to the latest version of the packages.

What version of ESLint are you using?

8.33.0

What version of eslint-plugin-svelte are you using?

2.22.0

What did you do?

Configuration

{
    "rules": {
        "@typescript-eslint/no-unsafe-member-access": "error"
    }
}

// routes/api/+server.ts
export const GET = async ({ request }) => {
    // request is not any, since it's inferred as Request by sveltekit
    request.headers // error: @typescript-eslint/no-unsafe-member-access
}

What did you expect to happen?

no error

What actually happened?

@typescript-eslint/no-unsafe-member-access error

Link to GitHub Repo with Minimal Reproducible Example

DetachHead/eslint-plugin-svelte-repros@7bf800d

Additional comments

originally raised at #390 (comment)

[ota-meshi]

Where are the types for GET sourced from? I don't understand the code you provided because there are no type declarations. Could you please share a repository to reproduce the issue?
I've only made static sites using svelte kit, so I'm not sure 😓

[DetachHead]

sveltekit infers the types so you don't have to annotate them explicitly. i've updated the issue with a github repo. to reproduce the error, checkout that branch then run the following commands

npm install
npm run check
npx eslint .

[polyzen]

Think you mean npx eslint .

[DetachHead]

true. i added ./node_modules/.bin to my path so i forgot about npx. updated my comment

[polyzen]

Inferring types is a new feature: https://svelte.dev/blog/zero-config-type-safety

[ota-meshi]

Thank you for the repo to reproduce.
It seems that the svelte language server and svelte-check assign their own types. (Because raw tsc command fails.)
I think we should check how it is implemented 👀.

[ota-meshi]

memo: Perhaps the following source code is injecting the type.

https://github.com/sveltejs/language-tools/blob/ac827294b4aff00ecac961b164155f29c0f5ed1d/packages/svelte2tsx/src/helpers/sveltekit.ts#L189

[ota-meshi]

Hmm.. We may need new typescript parser for the eslint (not svelte parser). We should check if it integrates well with svelte2tsx.

[jasonpanosso]

I still have this issue, is there any progress on this, or any known workaround/solution?

[thenbe]

Another minimal repro here: https://github.com/thenbe/repro-eslint-svelte-typecheck

Reproduction steps

1. Clone and pnpm install
2. Run: pnpm eslint src/routes/+page.svelte

Expected: We should get no eslint errors.
Actual: We get two eslint errors. Error message:

src/routes/+page.svelte
   7:20  error  Unsafe member access .url on an `any` value       @typescript-eslint/no-unsafe-member-access
  11:8   error  Unsafe member access .greeting on an `any` value  @typescript-eslint/no-unsafe-member-access

Other

svelte-check (i.e. pnpm run check) passes without errors. Only eslint shows error.

[ryoppippi]

Got the same issue....

So,

export async function load({ fetch }) {
	return await fetch('/foo');
}

this causes an error because fetch is inferred as any in eslint.
However, this works fine for svelte-check and svelte lsp

[keve1227]

A workaround is to import the offending type explicitly:

import type { RequestEvent } from "./$types";

export async function GET({ url }: RequestEvent) {
    return new Response(url.searchParams.get("message")); // no errors
}

Which gives correct linting.

[thenbe]

A workaround is to import the offending type explicitly

I wasn't sure how to apply this workaround to the minimal repro posted in the comment above.

The issue that remains is that eslint fails to see the inferred types not only in the +page.ts file, but in its sibling +page.svelte as well.

In other words, eslint does not play nice with sveltekit's zero-config-type-safety.