From 4655d699831b3356bb8be5b41c45da830dac9eb2 Mon Sep 17 00:00:00 2001
From: Evan You <yyx990803@gmail.com>
Date: Sun, 19 Jul 2020 13:22:58 -0400
Subject: [PATCH] fix(runtime-core/hmr): only use cloneNode mount optimization
 in prod

fix #1626
---
 packages/runtime-core/src/renderer.ts | 44 ++++++---------------------
 1 file changed, 9 insertions(+), 35 deletions(-)

diff --git a/packages/runtime-core/src/renderer.ts b/packages/runtime-core/src/renderer.ts
index 7f74d434..42e7f050 100644
--- a/packages/runtime-core/src/renderer.ts
+++ b/packages/runtime-core/src/renderer.ts
@@ -10,8 +10,7 @@ import {
   isSameVNodeType,
   Static,
   VNodeNormalizedRef,
-  VNodeHook,
-  isVNode
+  VNodeHook
 } from './vnode'
 import {
   ComponentInternalInstance,
@@ -639,31 +638,7 @@ function baseCreateRenderer(
         optimized
       )
     } else {
-      if (
-        __DEV__ &&
-        isHmrUpdating &&
-        hostCloneNode !== undefined &&
-        n2.patchFlag === PatchFlags.HOISTED
-      ) {
-        // https://github.com/vitejs/vite/issues/514
-        // reused hoisted trees are inserted with cloneNode
-        // which makes them not patch-able. In production hoisted trees are
-        // never patched (because they are not collected as dynamic nodes), but
-        // they can be udpated during HMR. In this case just mount it as new
-        // and remove the stale DOM tree.
-        mountElement(
-          n2,
-          container,
-          n1.el,
-          parentComponent,
-          parentSuspense,
-          isSVG,
-          optimized
-        )
-        hostRemove(n1.el!)
-      } else {
-        patchElement(n1, n2, parentComponent, parentSuspense, isSVG, optimized)
-      }
+      patchElement(n1, n2, parentComponent, parentSuspense, isSVG, optimized)
     }
   }
 
@@ -688,6 +663,7 @@ function baseCreateRenderer(
       dirs
     } = vnode
     if (
+      !__DEV__ &&
       vnode.el &&
       hostCloneNode !== undefined &&
       patchFlag === PatchFlags.HOISTED
@@ -695,6 +671,7 @@ function baseCreateRenderer(
       // If a vnode has non-null el, it means it's being reused.
       // Only static vnodes can be reused, so its mounted DOM nodes should be
       // exactly the same, and we can simply do a clone here.
+      // only do this in production since cloned trees cannot be HMR updated.
       el = vnode.el = hostCloneNode(vnode.el)
     } else {
       el = vnode.el = hostCreateElement(
@@ -2107,14 +2084,11 @@ function baseCreateRenderer(
     const ch2 = n2.children
     if (isArray(ch1) && isArray(ch2)) {
       for (let i = 0; i < ch1.length; i++) {
-        const c1 = ch1[i]
-        const c2 = ch2[i]
-        if (
-          isVNode(c1) &&
-          isVNode(c2) &&
-          c2.shapeFlag & ShapeFlags.ELEMENT &&
-          !c2.dynamicChildren
-        ) {
+        // this is only called in the optimized path so array children are
+        // guaranteed to be vnodes
+        const c1 = ch1[i] as VNode
+        const c2 = (ch2[i] = cloneIfMounted(ch2[i] as VNode))
+        if (c2.shapeFlag & ShapeFlags.ELEMENT && !c2.dynamicChildren) {
           if (c2.patchFlag <= 0) {
             c2.el = c1.el
           }