From c15311cfe879aa98c06585d731d996fca7633421 Mon Sep 17 00:00:00 2001
From: Evan You <yyx990803@gmail.com>
Date: Mon, 24 Aug 2020 21:30:04 -0400
Subject: [PATCH] fix(runtime-core): fix data merge order for mixins/extends

fix #1953
---
 .../runtime-core/__tests__/apiOptions.spec.ts | 33 +++++++++++--------
 packages/runtime-core/src/componentOptions.ts | 25 +++++++-------
 2 files changed, 30 insertions(+), 28 deletions(-)

diff --git a/packages/runtime-core/__tests__/apiOptions.spec.ts b/packages/runtime-core/__tests__/apiOptions.spec.ts
index 95fed1d7..d61d46be 100644
--- a/packages/runtime-core/__tests__/apiOptions.spec.ts
+++ b/packages/runtime-core/__tests__/apiOptions.spec.ts
@@ -446,7 +446,7 @@ describe('api: options', () => {
         calls.push('mixinA created')
         expect(this.a).toBe(1)
         expect(this.b).toBe(2)
-        expect(this.c).toBe(3)
+        expect(this.c).toBe(4)
       },
       mounted() {
         calls.push('mixinA mounted')
@@ -468,7 +468,7 @@ describe('api: options', () => {
         expect(this.a).toBe(1)
         expect(this.b).toBe(2)
         expect(this.bP).toBeUndefined()
-        expect(this.c).toBe(3)
+        expect(this.c).toBe(4)
         expect(this.cP1).toBeUndefined()
       },
       mounted() {
@@ -484,7 +484,8 @@ describe('api: options', () => {
       },
       created() {
         calls.push('mixinC created')
-        expect(this.c).toBe(3)
+        // component data() should overwrite mixin field with same key
+        expect(this.c).toBe(4)
         expect(this.cP1).toBeUndefined()
       },
       mounted() {
@@ -498,6 +499,7 @@ describe('api: options', () => {
       mixins: [defineComponent(mixinA), defineComponent(mixinB), mixinC],
       data() {
         return {
+          c: 4,
           z: 4
         }
       },
@@ -506,7 +508,7 @@ describe('api: options', () => {
         expect(this.a).toBe(1)
         expect(this.b).toBe(2)
         expect(this.bP).toBeUndefined()
-        expect(this.c).toBe(3)
+        expect(this.c).toBe(4)
         expect(this.cP2).toBeUndefined()
         expect(this.z).toBe(4)
       },
@@ -517,7 +519,7 @@ describe('api: options', () => {
         return `${this.a}${this.b}${this.c}`
       }
     })
-    expect(renderToString(h(Comp))).toBe(`123`)
+    expect(renderToString(h(Comp))).toBe(`124`)
     expect(calls).toEqual([
       'mixinA created',
       'mixinB created',
@@ -546,7 +548,8 @@ describe('api: options', () => {
     const Base = {
       data() {
         return {
-          a: 1
+          a: 1,
+          b: 1
         }
       },
       methods: {
@@ -582,7 +585,8 @@ describe('api: options', () => {
     const Base = {
       data() {
         return {
-          a: 1
+          a: 1,
+          x: 'base'
         }
       },
       methods: {
@@ -595,22 +599,23 @@ describe('api: options', () => {
         calls.push('base')
       }
     }
-    const Base2 = {
+    const Mixin = {
       data() {
         return {
-          b: true
+          b: true,
+          x: 'mixin'
         }
       },
       mounted(this: any) {
         expect(this.a).toBe(1)
         expect(this.b).toBeTruthy()
         expect(this.c).toBe(2)
-        calls.push('base2')
+        calls.push('mixin')
       }
     }
     const Comp = defineComponent({
       extends: defineComponent(Base),
-      mixins: [defineComponent(Base2)],
+      mixins: [defineComponent(Mixin)],
       data() {
         return {
           c: 2
@@ -620,12 +625,12 @@ describe('api: options', () => {
         calls.push('comp')
       },
       render() {
-        return `${this.a}${this.b}${this.c}`
+        return `${this.a}${this.b}${this.c}${this.x}`
       }
     })
 
-    expect(renderToString(h(Comp))).toBe(`1true2`)
-    expect(calls).toEqual(['base', 'base2', 'comp'])
+    expect(renderToString(h(Comp))).toBe(`1true2mixin`)
+    expect(calls).toEqual(['base', 'mixin', 'comp'])
   })
 
   test('accessing setup() state from options', async () => {
diff --git a/packages/runtime-core/src/componentOptions.ts b/packages/runtime-core/src/componentOptions.ts
index bb7a32ec..ff392700 100644
--- a/packages/runtime-core/src/componentOptions.ts
+++ b/packages/runtime-core/src/componentOptions.ts
@@ -485,24 +485,13 @@ export function applyOptions(
     }
   }
 
-  if (dataOptions) {
-    if (__DEV__ && !isFunction(dataOptions)) {
-      warn(
-        `The data option must be a function. ` +
-          `Plain object usage is no longer supported.`
-      )
-    }
-
-    if (asMixin) {
-      deferredData.push(dataOptions as DataFn)
-    } else {
-      resolveData(instance, dataOptions, publicThis)
-    }
-  }
   if (!asMixin) {
     if (deferredData.length) {
       deferredData.forEach(dataFn => resolveData(instance, dataFn, publicThis))
     }
+    if (dataOptions) {
+      resolveData(instance, dataOptions, publicThis)
+    }
     if (__DEV__) {
       const rawData = toRaw(instance.data)
       for (const key in rawData) {
@@ -518,6 +507,8 @@ export function applyOptions(
         }
       }
     }
+  } else if (dataOptions) {
+    deferredData.push(dataOptions as DataFn)
   }
 
   if (computedOptions) {
@@ -666,6 +657,12 @@ function resolveData(
   dataFn: DataFn,
   publicThis: ComponentPublicInstance
 ) {
+  if (__DEV__ && !isFunction(dataFn)) {
+    warn(
+      `The data option must be a function. ` +
+        `Plain object usage is no longer supported.`
+    )
+  }
   const data = dataFn.call(publicThis, publicThis)
   if (__DEV__ && isPromise(data)) {
     warn(