Version

3.1.1

Reproduction link

https://codesandbox.io/s/nifty-violet-mc6h7

Steps to reproduce

parent code：

export default defineComponent({
  name: 'LookupBase',
  setup (props, context) {
    const showLabel = ref('')
    return {
       showLabel 
    };
...
```javascript
extend code:
export default defineComponent({
  name: 'LookupLabel',
  props: {},
  extends: LookupBase,
  setup (props, context) {
     return {
         parentShowLabel: super.showLabel
     }
...

question1：mount LookupLabel after parent LookupBase setup not run?
chinese：挂载LookupLabel之后发现父组件不会执行steup()这个方法，super()?

question2：extend LookupLabel how quote parent LookupBase variable or function?
chinese：LookupLabel如何引用父组件的方法和变量？

### What is expected?
use

### What is actually happening?
vue2 have access to extends

---
Is it my usage or a bug?

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请问解决了么？有参考资料么？