fix(runtime-core): fix parent el update on nested HOC self-update (#1360)

fix #1357

packages/runtime-core/__tests__/rendererComponent.spec.ts

@@ -0,0 +1,44 @@
+import {
+  ref,
+  h,
+  render,
+  nodeOps,
+  serializeInner,
+  nextTick,
+  VNode
+} from '@vue/runtime-test'
+
+describe('renderer: component', () => {
+  test('should update parent(hoc) component host el when child component self update', async () => {
+    const value = ref(true)
+    let parentVnode: VNode
+    let childVnode1: VNode
+    let childVnode2: VNode
+
+    const Parent = {
+      render: () => {
+        // let Parent first rerender
+        console.log(value.value)
+        return (parentVnode = h(Child))
+      }
+    }
+
+    const Child = {
+      render: () => {
+        return value.value
+          ? (childVnode1 = h('div'))
+          : (childVnode2 = h('span'))
+      }
+    }
+
+    const root = nodeOps.createElement('div')
+    render(h(Parent), root)
+    expect(serializeInner(root)).toBe(`<div></div>`)
+    expect(parentVnode!.el).toBe(childVnode1!.el)
+
+    value.value = false
+    await nextTick()
+    expect(serializeInner(root)).toBe(`<span></span>`)
+    expect(parentVnode!.el).toBe(childVnode2!.el)
+  })
+})

packages/runtime-core/src/renderer.ts

@@ -1216,6 +1216,7 @@ function baseCreateRenderer(
       // no update needed. just copy over properties
       n2.component = n1.component
       n2.el = n1.el
+      instance.vnode = n2
     }
   }
 
@@ -1304,6 +1305,7 @@ function baseCreateRenderer(
         // This is triggered by mutation of component's own state (next: null)
         // OR parent calling processComponent (next: VNode)
         let { next, bu, u, parent, vnode } = instance
+        let originNext = next
         let vnodeHook: VNodeHook | null | undefined
         if (__DEV__) {
           pushWarningContext(next || instance.vnode)
@@ -1355,7 +1357,7 @@ function baseCreateRenderer(
           endMeasure(instance, `patch`)
         }
         next.el = nextTree.el
-        if (next === null) {
+        if (originNext === null) {
           // self-triggered update. In case of HOC, update parent component
           // vnode el. HOC is indicated by parent instance's subTree pointing
           // to child component's vnode