fix(runtime-core): fix beforeUpdate call timing to allow state mutation

fix #1899

packages/runtime-core/src/renderer.ts

@@ -1281,13 +1281,7 @@ function baseCreateRenderer(
         let vnodeHook: VNodeHook | null | undefined
         const { el, props } = initialVNode
         const { bm, m, parent } = instance
-        if (__DEV__) {
-          startMeasure(instance, `render`)
-        }
-        const subTree = (instance.subTree = renderComponentRoot(instance))
-        if (__DEV__) {
-          endMeasure(instance, `render`)
-        }
+
         // beforeMount hook
         if (bm) {
           invokeArrayFns(bm)
@@ -1296,6 +1290,16 @@ function baseCreateRenderer(
         if ((vnodeHook = props && props.onVnodeBeforeMount)) {
           invokeVNodeHook(vnodeHook, parent, initialVNode)
         }
+
+        // render
+        if (__DEV__) {
+          startMeasure(instance, `render`)
+        }
+        const subTree = (instance.subTree = renderComponentRoot(instance))
+        if (__DEV__) {
+          endMeasure(instance, `render`)
+        }
+
         if (el && hydrateNode) {
           if (__DEV__) {
             startMeasure(instance, `hydrate`)
@@ -1365,6 +1369,18 @@ function baseCreateRenderer(
         } else {
           next = vnode
         }
+        next.el = vnode.el
+
+        // beforeUpdate hook
+        if (bu) {
+          invokeArrayFns(bu)
+        }
+        // onVnodeBeforeUpdate
+        if ((vnodeHook = next.props && next.props.onVnodeBeforeUpdate)) {
+          invokeVNodeHook(vnodeHook, parent, next, vnode)
+        }
+
+        // render
         if (__DEV__) {
           startMeasure(instance, `render`)
         }
@@ -1374,15 +1390,7 @@ function baseCreateRenderer(
         }
         const prevTree = instance.subTree
         instance.subTree = nextTree
-        next.el = vnode.el
-        // beforeUpdate hook
-        if (bu) {
-          invokeArrayFns(bu)
-        }
-        // onVnodeBeforeUpdate
-        if ((vnodeHook = next.props && next.props.onVnodeBeforeUpdate)) {
-          invokeVNodeHook(vnodeHook, parent, next, vnode)
-        }
+
         // reset refs
         // only needed if previous patch had refs
         if (instance.refs !== EMPTY_OBJ) {