Generated types from `filesystem-routing` unassignable to `RouteDefinition` with TS `exactOptionalPropertyTypes`

[eyelidlessness]

Describe the bug

When TypeScript is configured with exactOptionalPropertyTypes: true, types generated by filesystem-routing are not assignable to the RouteDefinition type expected by @solidjs/router.

Your Example Website or App

Happy to put together minimal repro if necessary, it's really just basic project setup + one tsconfig setting

Steps to Reproduce the Bug or Issue

1. Set up basic project with latest Solid 2 RC, @solidjs/router, and filesystem-routing, and generated types (types: string | true).
2. In tsconfig.json, set "exactOptionalPropertyTypes": true
3. TS error is reproducible with config as simple as:

import { pageRoutes } from 'virtual:file-routes';
import { createRouter } from '@solidjs/router';
import { fileRoutes } from '@solidjs/router/fs';

export const Router = createRouter({
  routes: fileRoutes(pageRoutes),
  // ^ Error here
});

Expected behavior

Types generated by filesystem-routing should be assignable to the types expected by @solidjs/router.

Observed behavior: TypeScript errors due to optional properties assigned undefined values that are not explicitly allowed by RouteDefinition optional properties.

Screenshots or Videos

No response

Platform

• OS: macOS (but don't think it matters)
• Browser: N/A
• Version: N/A

---

I've confirmed this affects these versions (latest at time of writing):

• @solidjs/router: 2.0.0-next.21
• filesystem-routing: 0.3.0

Other Solid packages, in case it matters

• @solidjs/meta: 1.0.0-next.2
• @solidjs/vite-plugin: 3.0.0-next.38
• @solidjs/web: 2.0.0-rc.6
• solid-js: 2.0.0-rc.6

Additional context

Potential fix:

I've validated a trivial fix locally: in RouteDefinition, adding | undefined to each optional property¹. I'd be happy to contribute this change but I don't know:

• If it's the ideal place to address the issue (seems likely)
• Potential for type level regressions I haven't noticed yet
• How to test the change, or said potential regressions

I'm not sure how much appetite y'all have for adopting exactOptionalPropertyTypes internally, and fixing whatever other issues that come up. I'd be happy to look into a more thorough contribution in that vein!

Footnotes

1. Theoretically I only needed to make this change on the children property to eliminate the type errors I see. But I also saw potential for similar conflicts on others. ↩