Merge pull request #1965 from reduxjs/draft/amazing-rosalind

.github/workflows/test.yml

@@ -19,7 +19,7 @@ jobs:
       - name: Set up Node
         uses: actions/setup-node@v2
         with:
-          node-version: 14.x
+          node-version: 16.x
           cache: 'yarn'
 
       - name: Install dependencies
@@ -39,8 +39,8 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        node: ['14.x']
-        ts: ['4.0', '4.1', '4.2', '4.3', '4.4', '4.5', '4.6', 'next']
+        node: ['16.x']
+        ts: ['4.1', '4.2', '4.3', '4.4', '4.5', '4.6', '4.7', '4.8', '4.9.2-rc']
     steps:
       - name: Checkout repo
         uses: actions/checkout@v2

src/hooks/useSelector.ts

@@ -2,7 +2,7 @@ import { useContext, useDebugValue } from 'react'
 
 import { useReduxContext as useDefaultReduxContext } from './useReduxContext'
 import { ReactReduxContext } from '../components/Context'
-import type { EqualityFn } from '../types'
+import type { EqualityFn, NoInfer } from '../types'
 import type { uSESWS } from '../utils/useSyncExternalStore'
 import { notInitialized } from '../utils/useSyncExternalStore'
 
@@ -32,7 +32,7 @@ export function createSelectorHook(
 
   return function useSelector<TState, Selected extends unknown>(
     selector: (state: TState) => Selected,
-    equalityFn: EqualityFn<Selected> = refEquality
+    equalityFn: EqualityFn<NoInfer<Selected>> = refEquality
   ): Selected {
     if (process.env.NODE_ENV !== 'production') {
       if (!selector) {

src/types.ts

@@ -165,6 +165,8 @@ export type ResolveThunks<TDispatchProps> = TDispatchProps extends {
 export interface TypedUseSelectorHook<TState> {
   <TSelected>(
     selector: (state: TState) => TSelected,
-    equalityFn?: EqualityFn<TSelected>
+    equalityFn?: EqualityFn<NoInfer<TSelected>>
   ): TSelected
 }
+
+export type NoInfer<T> = [T][T extends any ? 0 : never]

test/typetests/hooks.tsx

@@ -34,7 +34,7 @@ import {
   fetchCount,
 } from './counterApp'
 
-import { expectType } from '../typeTestHelpers'
+import { expectType, expectExactType } from '../typeTestHelpers'
 
 function preTypedHooksSetup() {
   // Standard hooks setup
@@ -87,6 +87,20 @@ function testShallowEqual() {
   shallowEqual({ test: 'test' }, { test: 'test' })
   shallowEqual({ test: 'test' }, 'a')
   const x: boolean = shallowEqual('a', 'a')
+
+  type TestState = { stateProp: string }
+
+  // Additionally, it should infer its type from arguments and not become `any`
+  const selected1 = useSelector(
+    (state: TestState) => state.stateProp,
+    shallowEqual
+  )
+  expectExactType<string>(selected1)
+
+  const useAppSelector: TypedUseSelectorHook<TestState> = useSelector
+
+  const selected2 = useAppSelector((state) => state.stateProp, shallowEqual)
+  expectExactType<string>(selected2)
 }
 
 function testUseDispatch() {