Generated ActionData type from './$types' is always unknown

[harrylaulau]

Describe the bug

I tried to migrate my project to the newest sveltekit version but the ActionData type imported from './$types' is always unknown.

I then tried to reproduce the issue by creating a new project from scratch and the result is the same. I edited +page.svelte and added a +page.server.ts as follows.

+page.svelte

+page.server.ts

The error at the script tag complains another error, still I am not sure if that is related.

Reproduction

Git Repository

https://github.com/harrylaulau/sveltekittest

Steps

1. created with:
   npm create svelte@latest test
   Options: skeleton project, typescript, eslint, prttier enabled.
   

2. Edited Files:
   src/routes/+page.svelte

<script lang="ts">
	import type { ActionData } from './$types';
	export let form: ActionData;
	$: console.log(form?.success);
</script>

<h1>Welcome to SvelteKit</h1>
<p>Visit <a href="https://kit.svelte.dev">kit.svelte.dev</a> to read the documentation</p>
<form method="POST">
	<button>Log in</button>
</form>

src/routes/+page.server.ts

import type { Actions } from './$types';
export const actions: Actions = {
	default: async () => {
		return { success: true };
	}
};

Logs

console.log successfully output true when the form button is pressed

System Info

System:
    OS: macOS 12.5.1
    CPU: (10) arm64 Apple M1 Max
    Memory: 4.19 GB / 32.00 GB
    Shell: 5.8.1 - /bin/zsh
  Binaries:
    Node: 16.15.0 - ~/.nvm/versions/node/v16.15.0/bin/node
    Yarn: 1.22.19 - ~/Library/pnpm/yarn
    npm: 8.12.1 - ~/.nvm/versions/node/v16.15.0/bin/npm
    Watchman: 2022.08.15.00 - /opt/homebrew/bin/watchman
  Browsers:
    Chrome: 104.0.5112.101
    Safari: 15.6.1
  npmPackages:
    @sveltejs/adapter-auto: next => 1.0.0-next.71 
    @sveltejs/kit: next => 1.0.0-next.475 
    svelte: ^3.44.0 => 3.50.0 
    vite: ^3.1.0 => 3.1.0

Severity

serious, but I can work around it

Additional Information

This is from the generated $types.d.ts file. Not sure if this screen shot is helpful.

[harrylaulau]

Further testing by adding a if branch in actions.default returning a invalid()changes the return type of actions.default in generated $types.d.ts to Promise<any>

+page.server.ts

Generated $types.d.ts

[mattcroat]

I opened a discussion recently for #6597 which is interesting because it seems it's the same problem but now moved to ActionData.

[jeppech]

I think it's worth noting, that doing the same thing in a JS project, will work as expected. I've included both TS and a JS sample in #6668.

[aloker]

It's there any update on this? Do you need more input or better repos?

[williamviktorsson]

Thanks for the fix! The development experience when the types work is amazing 😍