From 593317603b70d12a3b198e8029bf5c542a87b884 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?=E8=8A=B1=E6=9E=9C=E5=B1=B1=E5=A4=A7=E5=9C=A3?=
 <316783812@qq.com>
Date: Tue, 27 Jun 2023 10:37:04 +0800
Subject: [PATCH 1/3] fix(reactivity): OnCleanup also needs to be cleaned

---
 .../runtime-core/__tests__/apiWatch.spec.ts   | 35 +++++++++++++++++++
 packages/runtime-core/src/apiWatch.ts         |  3 +-
 2 files changed, 37 insertions(+), 1 deletion(-)

diff --git a/packages/runtime-core/__tests__/apiWatch.spec.ts b/packages/runtime-core/__tests__/apiWatch.spec.ts
index f24ce80b9df..7a7e88032d9 100644
--- a/packages/runtime-core/__tests__/apiWatch.spec.ts
+++ b/packages/runtime-core/__tests__/apiWatch.spec.ts
@@ -1205,4 +1205,39 @@ describe('api: watch', () => {
     expect(countWE).toBe(3)
     expect(countW).toBe(2)
   })
+
+  // #5151
+  test('OnCleanup also needs to be cleaned，', async () => {
+    const spy1 = vi.fn()
+    const spy2 = vi.fn()
+    const num = ref(0)
+
+    watch(num, (value, oldValue, onCleanup) => {
+      if (value > 1) {
+        return
+      }
+      spy1()
+      onCleanup(() => {
+        // OnCleanup also needs to be cleaned
+        spy2()
+      })
+    })
+
+    num.value++
+    await nextTick()
+    expect(spy1).toHaveBeenCalledTimes(1)
+    expect(spy2).toHaveBeenCalledTimes(0)
+
+    num.value++
+    await nextTick()
+
+    expect(spy1).toHaveBeenCalledTimes(1)
+    expect(spy2).toHaveBeenCalledTimes(1)
+
+    num.value++
+    await nextTick()
+    // would not be calld when value>1
+    expect(spy1).toHaveBeenCalledTimes(1)
+    expect(spy2).toHaveBeenCalledTimes(1)
+  })
 })
diff --git a/packages/runtime-core/src/apiWatch.ts b/packages/runtime-core/src/apiWatch.ts
index 1b85ba12d19..71b15fd6e04 100644
--- a/packages/runtime-core/src/apiWatch.ts
+++ b/packages/runtime-core/src/apiWatch.ts
@@ -273,10 +273,11 @@ function doWatch(
     getter = () => traverse(baseGetter())
   }
 
-  let cleanup: () => void
+  let cleanup: (() => void) | undefined
   let onCleanup: OnCleanup = (fn: () => void) => {
     cleanup = effect.onStop = () => {
       callWithErrorHandling(fn, instance, ErrorCodes.WATCH_CLEANUP)
+      cleanup = effect.onStop = undefined
     }
   }
 

From bab625f14cc036bd58a5c5b221a3206be2f680fb Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?=E8=8A=B1=E6=9E=9C=E5=B1=B1=E5=A4=A7=E5=9C=A3?=
 <316783812@qq.com>
Date: Sun, 2 Jul 2023 20:31:10 +0800
Subject: [PATCH 2/3] chore: undefined to void

---
 packages/runtime-core/src/apiWatch.ts | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/packages/runtime-core/src/apiWatch.ts b/packages/runtime-core/src/apiWatch.ts
index 71b15fd6e04..2c75eda54d8 100644
--- a/packages/runtime-core/src/apiWatch.ts
+++ b/packages/runtime-core/src/apiWatch.ts
@@ -273,7 +273,7 @@ function doWatch(
     getter = () => traverse(baseGetter())
   }
 
-  let cleanup: (() => void) | undefined
+  let cleanup: (() => void) | void
   let onCleanup: OnCleanup = (fn: () => void) => {
     cleanup = effect.onStop = () => {
       callWithErrorHandling(fn, instance, ErrorCodes.WATCH_CLEANUP)

From b6a39f5dc3f2ce1f1c70e04e4bce56beb9b173ba Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?=E8=8A=B1=E6=9E=9C=E5=B1=B1=E5=A4=A7=E5=9C=A3?=
 <316783812@qq.com>
Date: Sun, 3 Sep 2023 21:49:58 +0800
Subject: [PATCH 3/3] chore:  void to undefined

Co-authored-by: Evan You <yyx990803@gmail.com>
---
 packages/runtime-core/src/apiWatch.ts | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/packages/runtime-core/src/apiWatch.ts b/packages/runtime-core/src/apiWatch.ts
index 2c75eda54d8..71b15fd6e04 100644
--- a/packages/runtime-core/src/apiWatch.ts
+++ b/packages/runtime-core/src/apiWatch.ts
@@ -273,7 +273,7 @@ function doWatch(
     getter = () => traverse(baseGetter())
   }
 
-  let cleanup: (() => void) | void
+  let cleanup: (() => void) | undefined
   let onCleanup: OnCleanup = (fn: () => void) => {
     cleanup = effect.onStop = () => {
       callWithErrorHandling(fn, instance, ErrorCodes.WATCH_CLEANUP)