fix(runtime-core): improve dedupe listeners when attr fallthrough (#4912)

fix #4859

Author: edison1105

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() {

packages/runtime-core/src/vnode.ts

@@ -791,7 +791,10 @@ export function mergeProps(...args: (Data & VNodeProps)[]) {
  } else if (isOn(key)) {
  const existing = ret[key]
  const incoming = toMerge[key]
- if (existing !== incoming) {
+ if (
+ existing !== incoming &&
+ !(isArray(existing) && existing.includes(incoming))
+ ) {
  ret[key] = existing
  ? [].concat(existing as any, incoming as any)
  : incoming