do not rely on symbol for filtering out redirects from loader data (#12694)

Author: pcattori

.changeset/calm-cycles-dress.md

@@ -0,0 +1,13 @@
+---
+"react-router": patch
+---
+
+Do not rely on `symbol` for filtering out `redirect` responses from loader data
+
+Previously, some projects were getting type checking errors like:
+
+```ts
+error TS4058: Return type of exported function has or is using name 'redirectSymbol' from external module "node_modules/..." but cannot be named.
+```
+
+Now that `symbol`s are not used for the `redirect` response type, these errors should no longer be present.

packages/react-router/lib/router/utils.ts

@@ -1367,12 +1367,7 @@ export interface TrackedPromise extends Promise<any> {
 export type RedirectFunction = (
   url: string,
   init?: number | ResponseInit
-) => Redirect;
-
-// use a `unique symbol` to create a branded type
-// https://egghead.io/blog/using-branded-types-in-typescript
-declare const redirectSymbol: unique symbol;
-export type Redirect = Response & { [redirectSymbol]: never };
+) => Response;
 
 /**
  * A redirect response. Sets the status code and the `Location` header.
@@ -1391,10 +1386,7 @@ export const redirect: RedirectFunction = (url, init = 302) => {
   let headers = new Headers(responseInit.headers);
   headers.set("Location", url);
 
-  return new Response(null, {
-    ...responseInit,
-    headers,
-  }) as Redirect;
+  return new Response(null, { ...responseInit, headers });
 };
 
 /**

packages/react-router/lib/types/route-data.ts

@@ -2,7 +2,7 @@ import type {
   ClientLoaderFunctionArgs,
   ClientActionFunctionArgs,
 } from "../dom/ssr/routeModules";
-import type { DataWithResponseInit, Redirect } from "../router/utils";
+import type { DataWithResponseInit } from "../router/utils";
 import type { Serializable } from "../server-runtime/single-fetch";
 import type { Equal, Expect, Func, IsAny, Pretty } from "./utils";
 
@@ -44,13 +44,13 @@ type DataFrom<T> =
 
 // prettier-ignore
 type ClientData<T> =
-  T extends Redirect ? never :
+  T extends Response ? never :
   T extends DataWithResponseInit<infer U> ? U :
   T
 
 // prettier-ignore
 type ServerData<T> =
-  T extends Redirect ? never :
+  T extends Response ? never :
   T extends DataWithResponseInit<infer U> ? Serialize<U> :
   Serialize<T>
 
@@ -86,7 +86,7 @@ type __tests = [
       | { data: string; b: Date; c: undefined }
     >
   >,
-  Expect<Equal<ServerDataFrom<() => { a: string } | Redirect>, { a: string }>>,
+  Expect<Equal<ServerDataFrom<() => { a: string } | Response>, { a: string }>>,
 
   // ClientDataFrom
   Expect<Equal<ClientDataFrom<any>, undefined>>,
@@ -109,5 +109,5 @@ type __tests = [
       | { data: string; b: Date; c: () => boolean }
     >
   >,
-  Expect<Equal<ClientDataFrom<() => { a: string } | Redirect>, { a: string }>>
+  Expect<Equal<ClientDataFrom<() => { a: string } | Response>, { a: string }>>
 ];