[Bug]: Layout routes with corresponding index routes cause clashing duplicate types

[wKovacs64]

I'm using React Router as a...

framework

Reproduction

Go to https://stackblitz.com/edit/github-8rw532i2?file=package.json and run npm run typecheck in the terminal.

System Info

System:
    OS: Linux 5.0 undefined
    CPU: (8) x64 Intel(R) Core(TM) i9-9880H CPU @ 2.30GHz
    Memory: 0 Bytes / 0 Bytes
    Shell: 1.0 - /bin/jsh
  Binaries:
    Node: 18.20.3 - /usr/local/bin/node
    Yarn: 1.22.19 - /usr/local/bin/yarn
    npm: 10.2.3 - /usr/local/bin/npm
    pnpm: 8.15.6 - /usr/local/bin/pnpm
  npmPackages:
    @react-router/dev: 7.2.0 => 7.2.0 
    @react-router/fs-routes: 7.2.0 => 7.2.0 
    @react-router/node: 7.2.0 => 7.2.0 
    @react-router/serve: 7.2.0 => 7.2.0 
    react-router: 7.2.0 => 7.2.0 
    vite: ^6.0.11 => 6.1.0

Used Package Manager

npm

Expected Behavior

I would expect it to handle routes like this that opt-out of nested layouts as 7.1.5 does.

Actual Behavior

npm run typecheck will fail with the following:

.react-router/types/+register.ts:11:3 - error TS2300: Duplicate identifier '/admin'.

11   "/admin": {};
     ~~~~~~~~

.react-router/types/+register.ts:12:3 - error TS2300: Duplicate identifier '/admin'.

12   "/admin": {};
     ~~~~~~~~


Found 2 errors in the same file, starting at: .react-router/types/+register.ts:11

Run cat .react-router/types/+register.ts and see the duplicate entries for /admin in the Params type:

import "react-router";

declare module "react-router" {
  interface Register {
    params: Params;
  }
}

type Params = {
  "/": {};
  "/admin": {};
  "/admin": {};
  "/admin/users": {};
  "/home": {};
};

This seems to happen when you have a layout route and an index route for the same path that opts out of said layout route. In this example:

<Routes>
  <Route file="root.tsx">
    {/* admin index route, opting out of admin layout */}
    <Route path="admin" index file="routes/admin_._index.tsx" />
    {/* admin layout route */}
    <Route path="admin" file="routes/admin.tsx">
      <Route path="users" file="routes/admin.users.tsx" />
    </Route>
    <Route path="home" file="routes/home.tsx" />
  </Route>
</Routes>

[gavinfaux]

Seeing same on previous working route.

// .\app\routes.ts
import { index, route, type RouteConfig } from '@react-router/dev/routes';

export default [
  route('/', './routes/home.tsx'),

  // index('./routes/home.tsx') does not work in this case
  // home.tsx contains component/form.tsx that posts to "root" (/), home has a server action (token validation) but errors with:
  // Route "root" does not have an action, but you are trying to submit to it. To fix this, please add an `action` function to the route
  
] satisfies RouteConfig;

typecheck now outputs:

// .react-router\types\+register.ts
import "react-router";

declare module "react-router" {
  interface Register {
    params: Params;
  }
}

type Params = {
  "/": {};
  "/": {};
};

adding an id with value root to the route route('/', './routes/home.tsx', { id: 'root' }), an invalid array length exception on running typecheck, while other values such as 'home', 'default', '1' etc don't resolve the duplicate Params.

RangeError: Invalid array length
    at Array.push (<anonymous>)
    at lineage (F:\ext\node_modules\.pnpm\@react-router+dev@7.2.0_@re_cc4b04ef99c091b95a3c5f462d2a13cd\node_modules\@react-router\dev\dist\cli\index.js:705:12)
    at generate2 (F:\ext\node_modules\.pnpm\@react-router+dev@7.2.0_@re_cc4b04ef99c091b95a3c5f462d2a13cd\node_modules\@react-router\dev\dist\cli\index.js:724:20)
    at F:\ext\node_modules\.pnpm\@react-router+dev@7.2.0_@re_cc4b04ef99c091b95a3c5f462d2a13cd\node_modules\@react-router\dev\dist\cli\index.js:852:21
    at Array.forEach (<anonymous>)
    at writeAll (F:\ext\node_modules\.pnpm\@react-router+dev@7.2.0_@re_cc4b04ef99c091b95a3c5f462d2a13cd\node_modules\@react-router\dev\dist\cli\index.js:850:36)
    at run (F:\ext\node_modules\.pnpm\@react-router+dev@7.2.0_@re_cc4b04ef99c091b95a3c5f462d2a13cd\node_modules\@react-router\dev\dist\cli\index.js:807:9)
    at typegen (F:\ext\node_modules\.pnpm\@react-router+dev@7.2.0_@re_cc4b04ef99c091b95a3c5f462d2a13cd\node_modules\@react-router\dev\dist\cli\index.js:1925:3)
    at run2 (F:\ext\node_modules\.pnpm\@react-router+dev@7.2.0_@re_cc4b04ef99c091b95a3c5f462d2a13cd\node_modules\@react-router\dev\dist\cli\index.js:2085:7)

[nakah]

Same error as @gavinfaux, duplicate "/" entries on register.ts file.
I had to downgrade to 7.1.5 to fix my pipeline.

[github-actions]

🤖 Hello there,

We just published version 7.3.0 which involves this issue. If you'd like to take it for a test run please try it out and let us know what you think!

Thanks!