Speed up type checking by explicitly annotating some type parameter variances

packages/toolkit/src/query/core/buildMiddleware/cacheLifecycle.ts

@@ -51,12 +51,12 @@ export interface QueryBaseLifecycleApi<
   updateCachedData(updateRecipe: Recipe<ResultType>): PatchCollection
 }
 
-export type MutationBaseLifecycleApi<
-  QueryArg,
-  BaseQuery extends BaseQueryFn,
-  ResultType,
-  ReducerPath extends string = string,
-> = LifecycleApi<ReducerPath> & {
+export interface MutationBaseLifecycleApi<
+  in QueryArg,
+  in BaseQuery extends BaseQueryFn,
+  in ResultType,
+  in ReducerPath extends string = string,
+> extends LifecycleApi<ReducerPath> {
   /**
    * Gets the current value of this cache entry.
    */
@@ -70,7 +70,7 @@ export type MutationBaseLifecycleApi<
   >
 }
 
-type LifecycleApi<ReducerPath extends string = string> = {
+type LifecycleApi<in ReducerPath extends string = string> = {
   /**
    * The dispatch method for the store
    */
@@ -89,7 +89,10 @@ type LifecycleApi<ReducerPath extends string = string> = {
   requestId: string
 }
 
-type CacheLifecyclePromises<ResultType = unknown, MetaType = unknown> = {
+type CacheLifecyclePromises<
+  out ResultType = unknown,
+  out MetaType = unknown,
+> = {
   /**
    * Promise that will resolve with the first value for this cache key.
    * This allows you to `await` until an actual value is in cache.
@@ -125,10 +128,10 @@ type CacheLifecyclePromises<ResultType = unknown, MetaType = unknown> = {
 }
 
 export interface QueryCacheLifecycleApi<
-  QueryArg,
-  BaseQuery extends BaseQueryFn,
-  ResultType,
-  ReducerPath extends string = string,
+  in QueryArg,
+  in BaseQuery extends BaseQueryFn,
+  out ResultType,
+  in ReducerPath extends string = string,
 > extends QueryBaseLifecycleApi<QueryArg, BaseQuery, ResultType, ReducerPath>,
     CacheLifecyclePromises<ResultType, BaseQueryMeta<BaseQuery>> {}
 

packages/toolkit/src/query/core/buildMiddleware/queryLifecycle.ts

@@ -200,10 +200,10 @@ export type QueryLifecycleMutationExtraOptions<
 }
 
 export interface QueryLifecycleApi<
-  QueryArg,
-  BaseQuery extends BaseQueryFn,
-  ResultType,
-  ReducerPath extends string = string,
+  in QueryArg,
+  in BaseQuery extends BaseQueryFn,
+  out ResultType,
+  in ReducerPath extends string = string,
 > extends QueryBaseLifecycleApi<QueryArg, BaseQuery, ResultType, ReducerPath>,
     QueryLifecyclePromises<ResultType, BaseQuery> {}
 

packages/toolkit/src/query/endpointDefinitions.ts

@@ -65,8 +65,8 @@ export type SchemaFailureConverter<BaseQuery extends BaseQueryFn> = (
 export type EndpointDefinitionWithQuery<
   QueryArg,
   BaseQuery extends BaseQueryFn,
-  ResultType,
-  RawResultType extends BaseQueryResult<BaseQuery>,
+  out ResultType,
+  out RawResultType extends BaseQueryResult<BaseQuery>,
 > = {
   /**
    * `query` can be a function that returns either a `string` or an `object` which is passed to your `baseQuery`. If you are using [fetchBaseQuery](./fetchBaseQuery), this can return either a `string` or an `object` of properties in `FetchArgs`. If you use your own custom [`baseQuery`](../../rtk-query/usage/customizing-queries), you can customize this behavior to your liking.
@@ -566,12 +566,13 @@ type QueryTypes<
  * @public
  */
 export interface QueryExtraOptions<
-  TagTypes extends string,
-  ResultType,
-  QueryArg,
-  BaseQuery extends BaseQueryFn,
-  ReducerPath extends string = string,
-  RawResultType extends BaseQueryResult<BaseQuery> = BaseQueryResult<BaseQuery>,
+  out TagTypes extends string,
+  in out ResultType,
+  in out QueryArg,
+  out BaseQuery extends BaseQueryFn,
+  out ReducerPath extends string = string,
+  out RawResultType extends
+    BaseQueryResult<BaseQuery> = BaseQueryResult<BaseQuery>,
 > extends CacheLifecycleQueryExtraOptions<
       ResultType,
       QueryArg,
@@ -872,13 +873,14 @@ export type InfiniteQueryTypes<
 }
 
 export interface InfiniteQueryExtraOptions<
-  TagTypes extends string,
-  ResultType,
-  QueryArg,
-  PageParam,
-  BaseQuery extends BaseQueryFn,
-  ReducerPath extends string = string,
-  RawResultType extends BaseQueryResult<BaseQuery> = BaseQueryResult<BaseQuery>,
+  out TagTypes extends string,
+  in out ResultType,
+  in out QueryArg,
+  in out PageParam,
+  out BaseQuery extends BaseQueryFn,
+  out ReducerPath extends string = string,
+  out RawResultType extends
+    BaseQueryResult<BaseQuery> = BaseQueryResult<BaseQuery>,
 > extends CacheLifecycleInfiniteQueryExtraOptions<
       InfiniteData<ResultType, PageParam>,
       QueryArg,
@@ -1089,12 +1091,13 @@ type MutationTypes<
  * @public
  */
 export interface MutationExtraOptions<
-  TagTypes extends string,
-  ResultType,
-  QueryArg,
-  BaseQuery extends BaseQueryFn,
-  ReducerPath extends string = string,
-  RawResultType extends BaseQueryResult<BaseQuery> = BaseQueryResult<BaseQuery>,
+  out TagTypes extends string,
+  in out ResultType,
+  in out QueryArg,
+  out BaseQuery extends BaseQueryFn,
+  out ReducerPath extends string = string,
+  out RawResultType extends
+    BaseQueryResult<BaseQuery> = BaseQueryResult<BaseQuery>,
 > extends CacheLifecycleMutationExtraOptions<
       ResultType,
       QueryArg,
@@ -1262,11 +1265,11 @@ export function isAnyQueryDefinition(
   return isQueryDefinition(e) || isInfiniteQueryDefinition(e)
 }
 
-export type EndpointBuilder<
-  BaseQuery extends BaseQueryFn,
-  TagTypes extends string,
-  ReducerPath extends string,
-> = {
+export interface EndpointBuilder<
+  out BaseQuery extends BaseQueryFn,
+  out TagTypes extends string,
+  out ReducerPath extends string,
+> {
   /**
    * An endpoint definition that retrieves data, and may provide tags to the cache.
    *

packages/toolkit/src/query/index.ts

@@ -1,6 +1,7 @@
 // This must remain here so that the `mangleErrors.cjs` build script
 // does not have to import this into each source file it rewrites.
 import { formatProdErrorMessage } from '@reduxjs/toolkit'
+import type { MutationBaseLifecycleApi } from './core/buildMiddleware/cacheLifecycle'
 
 export type {
   CombinedState,
@@ -104,3 +105,9 @@ export type {
 } from './tsHelpers'
 
 export { NamedSchemaError } from './standardSchema'
+
+// This is for type portability when using interfaces that we don't want to expose
+// interfaces are sometimes preferred over type aliases for faster type inference
+export declare namespace RTKInternalDoNotUse {
+  export { MutationBaseLifecycleApi }
+}