defineCustomElement props become readonly when component defines array emits

[andylizi]

Vue version

3.4.31

Link to minimal reproduction

https://stackblitz.com/edit/vue-ce-type-repro?file=src%2Fmain.ts

Steps to reproduce

Using the reproduction link:

1. Open the reproduction link and wait for npm install to finish.
2. Run npx vue-tsc
3. Observe type error.
4. Comment out the defineEmits line in counter.ce.vue, run vue-tsc again.
5. Observe that the type error disappears.

Manual setup:

const Comp1Vue = defineComponent({
  props: {
    a: Number,
  },
  emits: ['click'],
})
const Comp = defineCustomElement(Comp1Vue)

new Comp().a = 42   // property 'a' is read-only

What is expected?

No type error as props shouldn't be read-only.

What is actually happening?

src/main.ts:13:4 - error TS2540: Cannot assign to 'count' because it is a read-only property.

   el.count = 42;

This error only appears if defineEmits is present. It shows up in both vscode and vue-tsc.

System Info

No response

Any additional comments?

This is a variant of #7782, which was fixed by #7937 but only for object-style emit declarations. However, type-only emit declarations in SFCs are always compiled into arrays.

[yyx990803]

closed via #11384