fix(reactivity): should not trigger watch on computed ref when value is unchanged

fix #2231

packages/reactivity/src/ref.ts

@@ -7,13 +7,17 @@ import { CollectionTypes } from './collectionHandlers'
 declare const RefSymbol: unique symbol
 
 export interface Ref<T = any> {
+  value: T
   /**
    * Type differentiator only.
    * We need this to be in public d.ts but don't want it to show up in IDE
    * autocomplete, so we use a private Symbol instead.
    */
   [RefSymbol]: true
-  value: T
+  /**
+   * @internal
+   */
+  _shallow?: boolean
 }
 
 export type ToRefs<T = any> = { [K in keyof T]: Ref<T[K]> }
@@ -49,7 +53,7 @@ class RefImpl<T> {
 
   public readonly __v_isRef = true
 
-  constructor(private _rawValue: T, private readonly _shallow = false) {
+  constructor(private _rawValue: T, public readonly _shallow = false) {
     this._value = _shallow ? _rawValue : convert(_rawValue)
   }
 
@@ -75,7 +79,7 @@ function createRef(rawValue: unknown, shallow = false) {
 }
 
 export function triggerRef(ref: Ref) {
-  trigger(ref, TriggerOpTypes.SET, 'value', __DEV__ ? ref.value : void 0)
+  trigger(toRaw(ref), TriggerOpTypes.SET, 'value', __DEV__ ? ref.value : void 0)
 }
 
 export function unref<T>(ref: T): T extends Ref<infer V> ? V : T {