Describe the bug

Running vue-tsc in a project with vue of version 2.7 would report errors like this:

node_modules/@vueuse/shared/index.d.ts:200:26 - error TS2339: Property 'flush' does not exist on type 'WatchOptions'.

200     flush?: WatchOptions['flush'];

It seems that vue 2.7 exports WatchOptions for Options API, not for Composition API:

// node_modules/vue/types/index.d.ts
export {
  ...
  WatchOptions,
  WatchOptionsWithHandler,
  DirectiveFunction,
  DirectiveOptions
} from './options'

which has no flush property.
A possible fix is to re-export WatchOptions from vue/types/v3-generated in vue-demi for v2.7 like:

// vue-demi/lib/v2.7/index.d.ts
export * from 'vue'
export type { WatchOptions } from 'vue/types/v3-generated'

@antfu Any thoughts?

Reproduction

https://stackblitz.com/edit/vitejs-vite-z2pxyv?file=src/a.ts

Run npx vue-tsc

System Info

@vueuse/core: ^9.2.0 => 9.2.0 
    vue: ^2.7.3 => 2.7.10 

on StackBlitz

Used Package Manager

npm

Validations

• Follow our Code of Conduct
• Read the Contributing Guidelines.
• Read the docs.
• Check that there isn't already an issue that reports the same bug to avoid creating a duplicate.
• Make sure this is a VueUse issue and not a framework-specific issue. For example, if it's a Vue SFC related bug, it should likely be reported to https://github.com/vuejs/core instead.
• Check that this is a concrete bug. For Q&A open a GitHub Discussion.
• The provided reproduction is a minimal reproducible example of the bug.