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