New issue repro of issue #4640. It was closed with fix that appears to address a different issue. Apologies for reposting.

What problem does this feature solve?

An object with attributes of union type throws ts2322 in Volar when supplied to v-model for textarea, input (and others), when the attribute is specified in v-model. Type annotation would solve, and does do so with v-bind, but doesn't work with v-model. Ergo the only current workaround is to use a v-bind/@change combo where TS annotations can be used.

Example usecase:

interface MyType {
  data: string|Date,
}

Template:

<textarea v-model="arr[index].data as string" ...

where arr is a MyType[]

More info: https://github.com/johnsoncodehk/volar/issues/512

On the Volar side it seems its bundled compiler hasn't updated to incorporate d23fde3d yet. /cc @johnsoncodehk

It's not just a volar issue. I see a compilation error from vite and on the browser as well.

I know. Turns out the TS transpiler used in SFC playground (sucrase) is able to parse invalid TS syntax generated by the compiler... but esbuild will throw an error in this case.

Essentially:

v-bind="var as string" works, as expected ie. clearing any ts2322 error where valid. But v-model="var as string" does not and complains about invalid expression syntax.

Thanks for looking into this 👍