function defineComp<Bar, Data>(
  options: {
    bar: Bar,
    foo: () => Data
  } & ThisType<{ bar: Bar }>
): Bar
function defineComp(options: any) {
  return options.bar
}

// failed
const aaa = defineComp({
  foo() {
    console.log(this.bar) // no error
    return {
      count: this.bar() // throw error
    }
  },
  bar() {
    return '1'
  },
})

// work
const bbb = defineComp({
  bar() {
    return '1'
  },
  foo() {
    console.log(this.bar)
    return {
      count: this.bar() // it's work
    }
  },
})