fix(runtime-core): fix v-for ref reactivity behavior difference between prod and dev (vuejs#6714)

fix vuejs#6697

Author: baiwusanyu-c

Diff for: packages/runtime-core/__tests__/rendererTemplateRef.spec.ts

@@ -493,4 +493,50 @@ describe('api: template refs', () => {
     await nextTick()
     expect(mapRefs()).toMatchObject(['2', '3', '4'])
   })
+
+  // #6697 v-for ref behaves differently under production and development
+  test('named ref in v-for , should be responsive when rendering', async () => {
+    const list = ref([1, 2, 3])
+    const listRefs = ref([])
+    const App = {
+      setup() {
+        return { listRefs }
+      },
+      render() {
+        return h('div', null, [
+          h('div', null, String(listRefs.value)),
+          h(
+            'ul',
+            list.value.map(i =>
+              h(
+                'li',
+                {
+                  ref: 'listRefs',
+                  ref_for: true
+                },
+                i
+              )
+            )
+          )
+        ])
+      }
+    }
+    const root = nodeOps.createElement('div')
+    render(h(App), root)
+
+    await nextTick()
+    expect(String(listRefs.value)).toBe(
+      '[object Object],[object Object],[object Object]'
+    )
+    expect(serializeInner(root)).toBe(
+      '<div><div>[object Object],[object Object],[object Object]</div><ul><li>1</li><li>2</li><li>3</li></ul></div>'
+    )
+
+    list.value.splice(0, 1)
+    await nextTick()
+    expect(String(listRefs.value)).toBe('[object Object],[object Object]')
+    expect(serializeInner(root)).toBe(
+      '<div><div>[object Object],[object Object]</div><ul><li>2</li><li>3</li></ul></div>'
+    )
+  })
 })

Diff for: packages/runtime-core/src/rendererTemplateRef.ts

@@ -84,7 +84,11 @@ export function setRef(
     if (_isString || _isRef) {
       const doSet = () => {
         if (rawRef.f) {
-          const existing = _isString ? refs[ref] : ref.value
+          const existing = _isString
+            ? hasOwn(setupState, ref)
+              ? setupState[ref]
+              : refs[ref]
+            : ref.value
           if (isUnmount) {
             isArray(existing) && remove(existing, refValue)
           } else {