fix: infer V2 data from mixins

Author: gulewei

Diff for: types/test/vue-test.ts

@@ -255,6 +255,11 @@ new Vue({
         return {
           foo: 123
         }
+      },
+      computed: {
+        bar() {
+          return 123
+        }
       }
     },
     {
@@ -265,5 +270,6 @@ new Vue({
   ],
   created() {
     this.hello(this.foo)
+    this.hello(this.bar)
   }
 })

Diff for: types/v3-component-public-instance.d.ts

@@ -3,7 +3,7 @@ import {
   ShallowUnwrapRef,
   UnwrapNestedRefs
 } from './v3-generated'
-import { UnionToIntersection } from './common'
+import { IfAny, UnionToIntersection } from './common'
 
 import { Vue, VueConstructor } from './vue'
 import {
@@ -57,6 +57,12 @@ type IsDefaultMixinComponent<T> = T extends ComponentOptionsMixin
     : false
   : false
 
+type inferData<T> = T extends { data?: infer D }
+  ? D extends (this: Vue) => infer R
+    ? IfAny<R, {}, R>
+    : IfAny<D, {}, D>
+  : {}
+
 type MixinToOptionTypes<T> = T extends ComponentOptionsBase<
   infer P,
   infer B,
@@ -72,6 +78,29 @@ type MixinToOptionTypes<T> = T extends ComponentOptionsBase<
   ? OptionTypesType<P & {}, B & {}, D & {}, C & {}, M & {}, Defaults & {}> &
       IntersectionMixin<Mixin> &
       IntersectionMixin<Extends>
+  : // V3 data not assignable to V2 data
+  Omit<T, 'data'> extends ComponentOptionsBase<
+      infer P,
+      infer B,
+      any,
+      infer C,
+      infer M,
+      infer Mixin,
+      infer Extends,
+      any,
+      any,
+      infer Defaults
+    >
+  ? OptionTypesType<
+      P & {},
+      B & {},
+      inferData<T> & {},
+      C & {},
+      M & {},
+      Defaults & {}
+    > &
+      IntersectionMixin<Mixin> &
+      IntersectionMixin<Extends>
   : never
 
 // ExtractMixin(map type) is used to resolve circularly references

Diff for: types/vue.d.ts

@@ -18,6 +18,7 @@ import {
   UnwrapMixinsType,
   IntersectionMixin
 } from './v3-component-public-instance'
+import { ExtractComputedReturns } from './v3-component-options'
 
 export interface CreateElement {
   (
@@ -100,14 +101,6 @@ export interface Vue<
 
 type ComponentMixin = ComponentOptions<any, any, any, any, any>
 
-// IntersectionMixin cannot infer `data` from ComponentOptions<...>
-type PrepareMixinData<M extends ComponentMixin, D = Required<M>['data']> = {
-  [K in keyof M]: K extends 'data'
-    ? D extends (...args: any) => infer R
-      ? (this: any) => R
-      : (this: any) => D
-    : M[K]
-}
 export type CombinedVueInstance<
   Instance extends Vue,
   Data,
@@ -117,14 +110,14 @@ export type CombinedVueInstance<
   SetupBindings = {},
   Mixin extends ComponentMixin = ComponentMixin,
   Extends extends ComponentMixin = ComponentMixin,
-  PublicMixin = IntersectionMixin<PrepareMixinData<Mixin>> &
+  PublicMixin = IntersectionMixin<Mixin> &
     IntersectionMixin<Extends> &
     IntersectionMixin<ComponentOptions<any, any, any, any, any>> // prevent produce `never` in UnwrapMixinsType
 > = UnwrapMixinsType<PublicMixin, 'D'> &
   Data &
   UnwrapMixinsType<PublicMixin, 'M'> &
   Methods &
-  UnwrapMixinsType<PublicMixin, 'C'> &
+  ExtractComputedReturns<UnwrapMixinsType<PublicMixin, 'C'>> &
   Computed &
   UnwrapMixinsType<PublicMixin, 'P'> &
   Props &