fix(async-component): forward refs on async component wrapper

fix #2671

packages/runtime-core/src/apiAsyncComponent.ts

@@ -3,11 +3,12 @@ import {
   ConcreteComponent,
   currentInstance,
   ComponentInternalInstance,
-  isInSSRComponentSetup
+  isInSSRComponentSetup,
+  ComponentOptions
 } from './component'
 import { isFunction, isObject } from '@vue/shared'
 import { ComponentPublicInstance } from './componentPublicInstance'
-import { createVNode } from './vnode'
+import { createVNode, VNode } from './vnode'
 import { defineComponent } from './apiDefineComponent'
 import { warn } from './warning'
 import { ref } from '@vue/reactivity'
@@ -34,6 +35,9 @@ export interface AsyncComponentOptions<T = any> {
   ) => any
 }
 
+export const isAsyncWrapper = (i: ComponentInternalInstance | VNode): boolean =>
+  !!(i.type as ComponentOptions).__asyncLoader
+
 export function defineAsyncComponent<
   T extends Component = { new (): ComponentPublicInstance }
 >(source: AsyncComponentLoader<T> | AsyncComponentOptions<T>): T {
@@ -193,7 +197,10 @@ export function defineAsyncComponent<
 
 function createInnerComp(
   comp: ConcreteComponent,
-  { vnode: { props, children } }: ComponentInternalInstance
+  { vnode: { ref, props, children } }: ComponentInternalInstance
 ) {
-  return createVNode(comp, props, children)
+  const vnode = createVNode(comp, props, children)
+  // ensure inner component inherits the async wrapper's ref owner
+  vnode.ref = ref
+  return vnode
 }