Nextjs + SWC produces null __debugSource/_debugInfo

[givo]

Link to the code that reproduces this issue

https://github.com/vercel/next-learn/tree/main/dashboard/final-example

To Reproduce

1. Clone next-learn dashboard repo from nextjs-learn
2. set .swcrc to (optional - with or without this has no affect):

   {
   "jsc": {
   "target": "es2021",
   "parser": {
     "syntax": "typescript",
     "tsx": true
   },
   "transform": {
     "react": {
       "runtime": "automatic",
       "development": true,
       "refresh": true
     }
   }
   },
   "sourceMaps": true,
   "minify": false
   }

3. set next.config.mjs to (optional - with or without this has no affect):

   /** @type {import('next').NextConfig} */
   const nextConfig = {
   webpack(config, { dev }) {
   config.mode = 'development';
   config.devtool = 'source-map'; // nextjs automatically converts this to eval-source-map
   return config;
   },
   reactStrictMode: true,
   swcMinify: false,
   productionBrowserSourceMaps: true,
   };
   module.exports = nextConfig;

4. Run npm run dev

Current vs. Expected behavior

Expected:

• fiber nodes of React components should have _debugInfo with file name and line number

Actual

• _debugInfo is null

Provide environment information

React: 18.3.1
Nextjs: 14.2.4
Node: 20.13.1
Operating system: Mac 14.2.1

Which area(s) are affected? (Select all that apply)

Developer Experience, SWC

Which stage(s) are affected? (Select all that apply)

next dev (local)

Additional context

• As described here it used to work.
• I would also want to have _debugInfo in server side components, is it even possible?
• I don't want to use babel because SWC is much faster and I'm also afraid that it won't be supported for much longer

[leerob]

I'm a little confused:

• Why are you overriding the SWC config? This isn't necessary with the dashboard example
• The final dashboard example also don't have a custom webpack configuration, where did that come from?