fix(types/store): widen StateExt as type arguments

Author: exuanbo

src/createStore.ts

@@ -5,7 +5,8 @@ import {
   StoreEnhancer,
   Dispatch,
   Observer,
-  ListenerCallback
+  ListenerCallback,
+  UnknownIfNonSpecific
 } from './types/store'
 import { Action } from './types/actions'
 import { Reducer } from './types/reducers'
@@ -46,7 +47,7 @@ export function createStore<
 >(
   reducer: Reducer<S, A>,
   enhancer?: StoreEnhancer<Ext, StateExt>
-): Store<S, A, StateExt> & Ext
+): Store<S, A, UnknownIfNonSpecific<StateExt>> & Ext
 /**
  * @deprecated
  *
@@ -82,7 +83,7 @@ export function createStore<
   reducer: Reducer<S, A, PreloadedState>,
   preloadedState?: PreloadedState | undefined,
   enhancer?: StoreEnhancer<Ext, StateExt>
-): Store<S, A, StateExt> & Ext
+): Store<S, A, UnknownIfNonSpecific<StateExt>> & Ext
 export function createStore<
   S,
   A extends Action,
@@ -93,7 +94,7 @@ export function createStore<
   reducer: Reducer<S, A, PreloadedState>,
   preloadedState?: PreloadedState | StoreEnhancer<Ext, StateExt> | undefined,
   enhancer?: StoreEnhancer<Ext, StateExt>
-): Store<S, A, StateExt> & Ext {
+): Store<S, A, UnknownIfNonSpecific<StateExt>> & Ext {
   if (typeof reducer !== 'function') {
     throw new Error(
       `Expected the root reducer to be a function. Instead, received: '${kindOf(
@@ -432,7 +433,7 @@ export function legacy_createStore<
 >(
   reducer: Reducer<S, A>,
   enhancer?: StoreEnhancer<Ext, StateExt>
-): Store<S, A, StateExt> & Ext
+): Store<S, A, UnknownIfNonSpecific<StateExt>> & Ext
 /**
  * Creates a Redux store that holds the state tree.
  *
@@ -473,7 +474,7 @@ export function legacy_createStore<
   reducer: Reducer<S, A, PreloadedState>,
   preloadedState?: PreloadedState | undefined,
   enhancer?: StoreEnhancer<Ext, StateExt>
-): Store<S, A, StateExt> & Ext
+): Store<S, A, UnknownIfNonSpecific<StateExt>> & Ext
 export function legacy_createStore<
   S,
   A extends Action,
@@ -484,6 +485,6 @@ export function legacy_createStore<
   reducer: Reducer<S, A>,
   preloadedState?: PreloadedState | StoreEnhancer<Ext, StateExt> | undefined,
   enhancer?: StoreEnhancer<Ext, StateExt>
-): Store<S, A, StateExt> & Ext {
+): Store<S, A, UnknownIfNonSpecific<StateExt>> & Ext {
   return createStore(reducer, preloadedState as any, enhancer)
 }

src/types/store.ts

@@ -164,6 +164,8 @@ export interface Store<
   [Symbol.observable](): Observable<S & StateExt>
 }
 
+export type UnknownIfNonSpecific<T> = {} extends T ? unknown : T
+
 /**
  * A store creator is a function that creates a Redux store. Like with
  * dispatching function, we must distinguish the base store creator,
@@ -180,7 +182,7 @@ export interface StoreCreator {
   <S, A extends Action, Ext extends {} = {}, StateExt extends {} = {}>(
     reducer: Reducer<S, A>,
     enhancer?: StoreEnhancer<Ext, StateExt>
-  ): Store<S, A, StateExt> & Ext
+  ): Store<S, A, UnknownIfNonSpecific<StateExt>> & Ext
   <
     S,
     A extends Action,
@@ -191,7 +193,7 @@ export interface StoreCreator {
     reducer: Reducer<S, A, PreloadedState>,
     preloadedState?: PreloadedState | undefined,
     enhancer?: StoreEnhancer<Ext>
-  ): Store<S, A, StateExt> & Ext
+  ): Store<S, A, UnknownIfNonSpecific<StateExt>> & Ext
 }
 
 /**
@@ -223,7 +225,7 @@ export type StoreEnhancer<Ext extends {} = {}, StateExt extends {} = {}> = <
 ) => StoreEnhancerStoreCreator<NextExt & Ext, NextStateExt & StateExt>
 export type StoreEnhancerStoreCreator<
   Ext extends {} = {},
-  StateExt extends {} = {}
+  StateExt extends unknown = unknown
 > = <S, A extends Action, PreloadedState>(
   reducer: Reducer<S, A, PreloadedState>,
   preloadedState?: PreloadedState | undefined