tsconfig.json can no longer contain comments

[fabb]

Bug report

Describe the bug

When the tsconfig.json contains comments /* */, npm run dev will fail.

This seems to be a regression in 9.3.2, it used to work in 9.2.1.

To Reproduce

1. Have a tsconfig.json like this:

/* note that next.js currently cannot be configured to use another file than tsconfig.json, therefore we cannot rename it */
{
    "extends": "./tsconfig.base.json",
    "compilerOptions": {
        "jsx": "preserve",
        "lib": [
            "dom",
            "es2015",
            "es2016.array.include"
            /* this is set to a low target lib on purpose, because we do not polyfill modern browsers (only old ones like IE11) - only use modern api after checking if it's safe for the browsers we support */
        ],
        "module": "esnext",
        "noEmit": true
    },
    "exclude": [".server", "dist", ".next", "out", "next.config.js", "node_modules/**/*", "server"],
    "include": ["next-env.d.ts", "**/*.ts", "**/*.tsx"]
}

2. Run npm run dev

3. Observe error:

(node:15019) UnhandledPromiseRejectionWarning: SyntaxError: ./tsconfig.json: Unexpected token / in JSON at position 0
    at JSON.parse (<anonymous>)
    at Object.Module._extensions..json (internal/modules/cjs/loader.js:1005:27)
    at Module.load (internal/modules/cjs/loader.js:811:32)
    at Function.Module._load (internal/modules/cjs/loader.js:723:14)
    at Module.require (internal/modules/cjs/loader.js:848:19)
    at require (internal/modules/cjs/helpers.js:74:18)
    at getBaseWebpackConfig (./node_modules/next/dist/build/webpack-config.js:8:28)
    at async Promise.all (index 0)
    at HotReloader.start (./node_modules/next/dist/server/hot-reloader.js:14:1788)
    at DevServer.prepare (./node_modules/next/dist/server/next-dev-server.js:6:1541)

Expected behavior

npm run dev should start without errors.

System information

• OS: macOs Catalina
• Version of Next.js: 9.3.2

[timneutkens]

Thanks for the report! Opened a PR to fix it: #11392

[balazsorban44]

This issue has been automatically locked due to no recent activity. If you are running into a similar issue, please create a new issue with the steps to reproduce. Thank you.