Version

3.2.1

Reproduction link

https://sfc.vuejs.org/#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

Steps to reproduce

Hey,

when using multiple checkboxes, which are bound to the same array TS2322 arises. See the following image:

What is expected?

There shouldn't be a TS error when using an array as v-model.

checkbox's v-model prop is checked(https://v3.vuejs.org/guide/forms.html#basic-usage), and checked type is Booleanish = boolean | 'true' | 'false'(https://github.com/vuejs/vue-next/blob/7ffa225aa334f0fd7da6ba30bee9109de3597643/packages/runtime-dom/types/jsx.d.ts#L458), so number[] can't assign to checked in expected.

What is actually happening?

TS2322 error, since checked needs to be Booleanish.

It would be great it you could provide an acutal TS example we can run.

Sorry, I hope this helps: https://codesandbox.io/s/admiring-sky-ucmn0?file=/src/components/HelloWorld.vue

It seems to be only showing this in VS Code with Volar, at least from what I can tell.

@johnsoncodehk can you confirm the problem is within vue?

I personal think this is InputHTMLAttributes types problem, hope this comment helpful: https://github.com/johnsoncodehk/vue-tsc/issues/57#issuecomment-897276138

@johnsoncodehk 77223df2 should fix the following cases:

• checkbox with Array v-model value
• <input> with non-primitive value bindings

However the case for radio needs to be fixed in Volar. Volar is mapping the v-model on a radio input to checked, which is incorrect:

<input type="radio" v-model="selected" :value="foo">
<input type="radio" v-model="selected" :value="bar">

Here v-model's binding type should be the same as :value. Not sure if this can be inferred, but at least it should be any instead of Booleanish.