fix(types): fix defineComponent inference to Component (#5949)

test-dts/defineComponent.test-d.tsx

@@ -1,5 +1,6 @@
 import {
   describe,
+  test,
   Component,
   defineComponent,
   PropType,
@@ -1045,7 +1046,7 @@ describe('emits', () => {
 })
 
 describe('componentOptions setup should be `SetupContext`', () => {
-  expect<ComponentOptions['setup']>(
+  expectType<ComponentOptions['setup']>(
     {} as (props: Record<string, any>, ctx: SetupContext) => any
   )
 })
@@ -1141,6 +1142,20 @@ describe('async setup', () => {
   vm.a = 2
 })
 
+// #5948
+describe('DefineComponent should infer correct types when assigning to Component', () => {
+  let component: Component
+  component = defineComponent({
+    setup(_, { attrs, slots }) {
+      // @ts-expect-error should not be any
+      expectType<[]>(attrs)
+      // @ts-expect-error should not be any
+      expectType<[]>(slots)
+    }
+  })
+  expectType<Component>(component)
+})
+
 // check if defineComponent can be exported
 export default {
   // function components

test-dts/index.d.ts

@@ -4,6 +4,7 @@
 export * from '@vue/runtime-dom'
 
 export function describe(_name: string, _fn: () => void): void
+export function test(_name: string, _fn: () => any): void
 
 export function expectType<T>(value: T): void
 export function expectError<T>(value: T): void
@@ -15,4 +16,4 @@ export type IsUnion<T, U extends T = T> = (
   ? false
   : true
 
-export type IsAny<T> = 0 extends (1 & T) ? true : false
+export type IsAny<T> = 0 extends 1 & T ? true : false