fix(reactivity): ensure computed re-evaluates after dep cleanup

packages/reactivity/__tests__/computed.spec.ts

@@ -1037,4 +1037,22 @@ describe('reactivity/computed', () => {
     state.a++
     expect(pp.value).toBe(2)
   })
+
+  test('computed value updates correctly after dep cleanup', () => {
+    const obj = reactive({ foo: 1, flag: 1 })
+    const c1 = computed(() => obj.foo)
+
+    let foo
+    effect(() => {
+      foo = obj.flag ? (obj.foo, c1.value) : 0
+    })
+    expect(foo).toBe(1)
+
+    obj.flag = 0
+    expect(foo).toBe(0)
+
+    obj.foo = 2
+    obj.flag = 1
+    expect(foo).toBe(2)
+  })
 })

packages/reactivity/src/effect.ts

@@ -321,7 +321,7 @@ function cleanupDeps(sub: Subscriber, fromComputed = false) {
   sub.depsTail = tail
 }
 
-function isDirty(sub: Subscriber): boolean {
+function isDirty(sub: Subscriber, isComputed = false): boolean {
   for (let link = sub.deps; link; link = link.nextDep) {
     if (
       link.dep.version !== link.version ||
@@ -331,6 +331,14 @@ function isDirty(sub: Subscriber): boolean {
     ) {
       return true
     }
+
+    if (
+      isComputed &&
+      link.dep.map &&
+      link.dep.map.get(link.dep.key) !== link.dep
+    ) {
+      return true
+    }
   }
   // @ts-expect-error only for backwards compatibility where libs manually set
   // this flag - e.g. Pinia's testing module
@@ -370,7 +378,7 @@ export function refreshComputed(computed: ComputedRefImpl): undefined {
     dep.version > 0 &&
     !computed.isSSR &&
     computed.deps &&
-    !isDirty(computed)
+    !isDirty(computed, true)
   ) {
     computed.flags &= ~EffectFlags.RUNNING
     return