v1.8.10 Generics: defineComponent missing type overload definition when importing a script setup generic component

[Chuuone]

Importing a child component defined using <script setup lang="ts" generic="T extends Record">
into a component defined using <script lang="ts"> and defineComponent() will cause typing issue specified below.

Example breakdown
Define a child component
// TableComponent.vue

<script setup lang="ts" generic="TRow extends DataType = DataType">

Create a parent component defined using
MainComponent.vue

<script lang="ts">
import TableComponent from "TableComponent.vue";

defineComponent({components: {TableComponent});
</script>

The typing issue

[Chuuone]

#2709 Reoccurrance of this problem

[so1ve]

Not sure why, but I can't reproduce it now.

[Chuuone]

Not sure why, but I can't reproduce it now.

I just tried it in v.1.8.11 in case it was fixed there. Unfortunately isn't.

Are you reproducing in stackblitz or vscode? I've found the issue is not reproducible in stackblitz.

[so1ve]

In vscode. This is my reproduction: https://github.com/so1ve/language-tools/tree/fix/issue-3257. Am I doing something wrong? Maybe related to your vue / typescript version?

[Chuuone]

Your parent component seems to have a script setup <script setup lang="ts"> and export defineComponent() all in one. In my example we just use defineComponent on parent and setup generic in child. :)

Is using both valid or a mistake?

[so1ve]

:(

I didn't export the component inside script setup; I just called defineComponent to check if the type works.

[Chuuone]

Alright, that is odd. Well i am using ts 5.2.2 and Volar 1.8.11. I think i need to try to fork your test and see if it behaves then in case something in my project is throwing things off.

Out of curiosity, are shims defined in your test?

declare module "*.vue" {
	import type {DefineComponent} from "vue";

	const component: DefineComponent<{}, {}, any>;

	export default component;
  }

[so1ve]

No :D You don't need this if you enable take over mode.

[Chuuone]

Think i need some help with the fork. I forked the project, checked out your branch fix/issue-3257

Ran npm i
npm i

The problem is, there is no type hinting going on whatsoever. Note how i am using a Comp thats not defined, and things do not hint.

Update

Figured it out how to setup the fork; had to install some extra things.

The type hinting is working here for me too. Going to look into this more.

[Chuuone]

I think i figured it out. The error happens due to the new emits syntax introduced in 3.3+

Here is a minimal reproduction.

Comp.d.ts

<script setup lang="ts" generic="TRow extends DataType = DataType">
import type {DataType} from "./Comp";

/* Taken from https://vuejs.org/api/sfc-script-setup.html#defineprops-defineemits */
export type Emits = {
  change: [id: number] // named tuple syntax
  update: [value: string]
};

defineEmits<Emits>();
</script>

[so1ve]

Thanks @Chuuone, this reproduction works 👍