From ffbe87e7a3bda9666245e7e5b1565cd35b9cc5ea Mon Sep 17 00:00:00 2001
From: daiwei <daiwei521@126.com>
Date: Tue, 31 Dec 2024 16:11:41 +0800
Subject: [PATCH 1/2] fix(runtime-core): prevent updating instance if it's
 already the current instance

---
 packages/runtime-core/src/component.ts | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/packages/runtime-core/src/component.ts b/packages/runtime-core/src/component.ts
index 3ed42ed0b55..cf8a17e9d2b 100644
--- a/packages/runtime-core/src/component.ts
+++ b/packages/runtime-core/src/component.ts
@@ -760,7 +760,10 @@ if (__SSR__) {
   }
 }
 
-export const setCurrentInstance = (instance: ComponentInternalInstance) => {
+export const setCurrentInstance = (
+  instance: ComponentInternalInstance,
+): (() => void) => {
+  if (currentInstance === instance) return NOOP
   const prev = currentInstance
   internalSetCurrentInstance(instance)
   instance.scope.on()

From acb325c13cd393472e0d2561ce220953e5af939d Mon Sep 17 00:00:00 2001
From: daiwei <daiwei521@126.com>
Date: Tue, 31 Dec 2024 16:20:18 +0800
Subject: [PATCH 2/2] test: add test case

---
 .../runtime-core/__tests__/apiWatch.spec.ts   | 27 +++++++++++++++++++
 1 file changed, 27 insertions(+)

diff --git a/packages/runtime-core/__tests__/apiWatch.spec.ts b/packages/runtime-core/__tests__/apiWatch.spec.ts
index 7d2a1e73c08..40b45922375 100644
--- a/packages/runtime-core/__tests__/apiWatch.spec.ts
+++ b/packages/runtime-core/__tests__/apiWatch.spec.ts
@@ -6,6 +6,7 @@ import {
   getCurrentInstance,
   nextTick,
   onErrorCaptured,
+  onScopeDispose,
   onWatcherCleanup,
   reactive,
   ref,
@@ -1362,6 +1363,32 @@ describe('api: watch', () => {
     expect(source.mock.calls.some(args => args.includes(instance)))
   })
 
+  test('this.$watch w/ onScopeDispose', () => {
+    const onCleanup = vi.fn()
+    const toggle = ref(true)
+
+    const Comp = defineComponent({
+      render() {},
+      created(this: any) {
+        this.$watch(
+          () => 1,
+          function () {},
+        )
+        onScopeDispose(onCleanup)
+      },
+    })
+
+    const App = defineComponent({
+      render() {
+        return toggle.value ? h(Comp) : null
+      },
+    })
+
+    const root = nodeOps.createElement('div')
+    createApp(App).mount(root)
+    expect(onCleanup).toBeCalledTimes(0)
+  })
+
   test('should not leak `this.proxy` to setup()', () => {
     const source = vi.fn()