Avoid passing an identity function to createSelector

Author: EskiMojo14

packages/toolkit/src/query/react/buildHooks.ts

@@ -541,9 +541,6 @@ export type MutationTrigger<D extends MutationDefinition<any, any, any, any>> =
     (arg: QueryArgFrom<D>): MutationActionCreatorResult<D>
   }
 
-const defaultQueryStateSelector: QueryStateSelector<any, any> = (x) => x
-const defaultMutationStateSelector: MutationStateSelector<any, any> = (x) => x
-
 /**
  * Wrapper around `defaultQueryStateSelector` to be used in `useQuery`.
  * We want the initial render to already come back with
@@ -989,10 +986,7 @@ export function buildHooks<Definitions extends EndpointDefinitions>({
   }
 
   function buildMutationHook(name: string): UseMutation<any> {
-    return ({
-      selectFromResult = defaultMutationStateSelector,
-      fixedCacheKey,
-    } = {}) => {
+    return ({ selectFromResult, fixedCacheKey } = {}) => {
       const { select, initiate } = api.endpoints[name] as ApiEndpointMutation<
         MutationDefinition<any, any, any, any, any>,
         Definitions
@@ -1019,13 +1013,16 @@ export function buildHooks<Definitions extends EndpointDefinitions>({
       )
 
       const { requestId } = promise || {}
+      const initialSelector = useMemo(
+        () => select({ fixedCacheKey, requestId: promise?.requestId }),
+        [fixedCacheKey, promise, select]
+      )
       const mutationSelector = useMemo(
         () =>
-          createSelector(
-            [select({ fixedCacheKey, requestId: promise?.requestId })],
-            selectFromResult
-          ),
-        [select, promise, selectFromResult, fixedCacheKey]
+          selectFromResult
+            ? createSelector([initialSelector], selectFromResult)
+            : initialSelector,
+        [selectFromResult, initialSelector]
       )
 
       const currentState = useSelector(mutationSelector, shallowEqual)

packages/toolkit/tsconfig.base.json

@@ -43,7 +43,8 @@
       // for type imports in tests only
       "@reduxjs/toolkit/dist/query/*": ["src/query/*"], // @remap-prod-remove-line
       // internal imports in tests only
-      "@internal/*": ["src/*"]
+      "@internal/*": ["src/*"],
+      "react": ["node_modules/react"]
     }
   }
 }