From 74bd85218dfb7853873ab04f5d85029a47d5507e Mon Sep 17 00:00:00 2001
From: daiwei <daiwei521@126.com>
Date: Sun, 7 Nov 2021 14:06:58 +0800
Subject: [PATCH 1/2] fix(runtime-core): improve dedupe listeners when attr
 fallthrough

---
 .../rendererAttrsFallthrough.spec.ts          | 42 ++++++++++++++++++-
 packages/runtime-core/src/vnode.ts            |  2 +
 2 files changed, 43 insertions(+), 1 deletion(-)

diff --git a/packages/runtime-core/__tests__/rendererAttrsFallthrough.spec.ts b/packages/runtime-core/__tests__/rendererAttrsFallthrough.spec.ts
index d358431d66b..f23cdf6a27c 100644
--- a/packages/runtime-core/__tests__/rendererAttrsFallthrough.spec.ts
+++ b/packages/runtime-core/__tests__/rendererAttrsFallthrough.spec.ts
@@ -11,7 +11,8 @@ import {
   createBlock,
   FunctionalComponent,
   createCommentVNode,
-  Fragment
+  Fragment,
+  withModifiers
 } from '@vue/runtime-dom'
 import { PatchFlags } from '@vue/shared/src'
 
@@ -383,6 +384,45 @@ describe('attribute fallthrough', () => {
     expect(`Extraneous non-emits event listeners`).toHaveBeenWarned()
   })
 
+  it('should dedupe same listeners when $attrs is used during render', () => {
+    const click = jest.fn()
+    const count = ref(0)
+
+    function inc() {
+      count.value++
+      click()
+    }
+
+    const Parent = {
+      render() {
+        return h(Child, { onClick: inc })
+      }
+    }
+
+    const Child = defineComponent({
+      render() {
+        return h(
+          'div',
+          mergeProps(
+            {
+              onClick: withModifiers(() => {}, ['prevent', 'stop'])
+            },
+            this.$attrs
+          )
+        )
+      }
+    })
+
+    const root = document.createElement('div')
+    document.body.appendChild(root)
+    render(h(Parent), root)
+
+    const node = root.children[0] as HTMLElement
+    node.dispatchEvent(new CustomEvent('click'))
+    expect(click).toHaveBeenCalledTimes(1)
+    expect(count.value).toBe(1)
+  })
+
   it('should not warn when $attrs is used during render', () => {
     const Parent = {
       render() {
diff --git a/packages/runtime-core/src/vnode.ts b/packages/runtime-core/src/vnode.ts
index 089147a38f7..86bc722bcba 100644
--- a/packages/runtime-core/src/vnode.ts
+++ b/packages/runtime-core/src/vnode.ts
@@ -792,6 +792,8 @@ export function mergeProps(...args: (Data & VNodeProps)[]) {
         const existing = ret[key]
         const incoming = toMerge[key]
         if (existing !== incoming) {
+          if (isArray(existing) && existing.indexOf(incoming) !== -1) continue
+
           ret[key] = existing
             ? [].concat(existing as any, incoming as any)
             : incoming

From 0f9d724028bcb09382177eaf0fefb93f7fa0c66a Mon Sep 17 00:00:00 2001
From: Evan You <yyx990803@gmail.com>
Date: Sun, 14 Nov 2021 22:14:51 -0500
Subject: [PATCH 2/2] Update vnode.ts

---
 packages/runtime-core/src/vnode.ts | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/packages/runtime-core/src/vnode.ts b/packages/runtime-core/src/vnode.ts
index 86bc722bcba..306afbcc3d2 100644
--- a/packages/runtime-core/src/vnode.ts
+++ b/packages/runtime-core/src/vnode.ts
@@ -791,9 +791,10 @@ export function mergeProps(...args: (Data & VNodeProps)[]) {
       } else if (isOn(key)) {
         const existing = ret[key]
         const incoming = toMerge[key]
-        if (existing !== incoming) {
-          if (isArray(existing) && existing.indexOf(incoming) !== -1) continue
-
+        if (
+          existing !== incoming &&
+          !(isArray(existing) && existing.includes(incoming))
+        ) {
           ret[key] = existing
             ? [].concat(existing as any, incoming as any)
             : incoming