Only apply mapped types to un-branded types (#3805)

Author: invliD

index.d.ts

@@ -69,7 +69,9 @@ export type PreloadedState<S> = Required<S> extends {
       }
     : never
   : {
-      [K in keyof S]: S[K] extends object ? PreloadedState<S[K]> : S[K]
+      [K in keyof S]: S[K] extends (string | number | boolean | symbol)
+        ? S[K]
+        : PreloadedState<S[K]>
     }
 
 /* reducers */

package-lock.json

@@ -84,7 +84,7 @@
     "rollup-plugin-replace": "^2.2.0",
     "rollup-plugin-terser": "^5.1.1",
     "rxjs": "^6.5.2",
-    "typescript": "^3.5.3",
+    "typescript": "^3.9.6",
     "typings-tester": "^0.3.2"
   },
   "npmName": "redux",

package.json

@@ -11,12 +11,16 @@ import {
 } from 'redux'
 import 'symbol-observable'
 
+type BrandedString = string & { _brand: 'type' }
+const brandedString = 'a string' as BrandedString
+
 type State = {
   a: 'a'
   b: {
     c: 'c'
     d: 'd'
   }
+  c: BrandedString
 }
 
 interface DerivedAction extends Action {
@@ -30,7 +34,8 @@ const reducer: Reducer<State> = (
     b: {
       c: 'c',
       d: 'd'
-    }
+    },
+    c: brandedString
   },
   action: Action
 ): State => {
@@ -43,7 +48,8 @@ const reducerWithAction: Reducer<State, DerivedAction> = (
     b: {
       c: 'c',
       d: 'd'
-    }
+    },
+    c: brandedString
   },
   action: DerivedAction
 ): State => {
@@ -58,17 +64,20 @@ const store: Store<State> = createStore(reducer)
 
 const storeWithPreloadedState: Store<State> = createStore(reducer, {
   a: 'a',
-  b: { c: 'c', d: 'd' }
+  b: { c: 'c', d: 'd' },
+  c: brandedString
 })
 // typings:expect-error
 const storeWithBadPreloadedState: Store<State> = createStore(reducer, {
-  b: { c: 'c' }
+  b: { c: 'c' },
+  c: brandedString
 })
 
 const storeWithActionReducer = createStore(reducerWithAction)
 const storeWithActionReducerAndPreloadedState = createStore(reducerWithAction, {
   a: 'a',
-  b: { c: 'c', d: 'd' }
+  b: { c: 'c', d: 'd' },
+  c: brandedString
 })
 funcWithStore(storeWithActionReducer)
 funcWithStore(storeWithActionReducerAndPreloadedState)
@@ -77,7 +86,8 @@ funcWithStore(storeWithActionReducerAndPreloadedState)
 const storeWithActionReducerAndBadPreloadedState = createStore(
   reducerWithAction,
   {
-    b: { c: 'c' }
+    b: { c: 'c' },
+    c: brandedString
   }
 )
 
@@ -89,7 +99,8 @@ const storeWithPreloadedStateAndEnhancer: Store<State> = createStore(
   reducer,
   {
     a: 'a',
-    b: { c: 'c', d: 'd' }
+    b: { c: 'c', d: 'd' },
+    c: brandedString
   },
   enhancer
 )