fix(types): keep the original type when unwrapping markRaw (#3791)

test-dts/reactivity.test-d.ts

@@ -1,5 +1,14 @@
-import { shallowReadonly } from '@vue/reactivity'
-import { ref, readonly, describe, expectError, expectType, Ref } from './index'
+import {
+  ref,
+  readonly,
+  shallowReadonly,
+  describe,
+  expectError,
+  expectType,
+  Ref,
+  reactive,
+  markRaw
+} from './index'
 
 describe('should support DeepReadonly', () => {
   const r = readonly({ obj: { k: 'v' } })
@@ -15,6 +24,35 @@ describe('readonly ref', () => {
   expectType<Ref>(r)
 })
 
+describe('should support markRaw', () => {
+  class Test<T> {
+    item = {} as Ref<T>
+  }
+  const test = new Test<number>()
+  const plain = {
+    ref: ref(1)
+  }
+
+  const r = reactive({
+    class: {
+      raw: markRaw(test),
+      reactive: test
+    },
+    plain: {
+      raw: markRaw(plain),
+      reactive: plain
+    }
+  })
+
+  expectType<Test<number>>(r.class.raw)
+  // @ts-expect-error it should unwrap
+  expectType<Test<number>>(r.class.reactive)
+
+  expectType<Ref<number>>(r.plain.raw.ref)
+  // @ts-expect-error it should unwrap
+  expectType<Ref<number>>(r.plain.reactive.ref)
+})
+
 describe('shallowReadonly ref unwrap', () => {
   const r = shallowReadonly({ count: { n: ref(1) } })
   // @ts-expect-error