[NEXT-665] TypeScript error when using generateMetadata() in WebStorm IDE

[patrykszwed]

Verify canary release

• I verified that the issue exists in the latest Next.js canary release

Provide environment information

Operating System:
  Platform: win32
  Arch: x64
  Version: Windows 10 Pro
Binaries:
  Node: 18.13.0
  npm: N/A
  Yarn: N/A
  pnpm: N/A
Relevant packages:
  next: 13.2.2-canary.1
  eslint-config-next: N/A
  react: 18.2.0
  react-dom: 18.2.0

Which area(s) of Next.js are affected? (leave empty if unsure)

App directory (appDir: true), Metadata (metadata, generateMetadata, next/head, head.js), TypeScript

Link to the code that reproduces this issue

https://github.com/patrykszwed/next-metadata-ts-error

To Reproduce

1. Run npx create-next-app --example reproduction-template-app-dir reproduction-app
2. Add generateMetadata function to page.tsx at a root level. That code should be enough:

export async function generateMetadata() {
  return {};
}

export default function Home() {
  return null
}

Describe the Bug

When implementing a generateMetadata function and opening a project in WebStorm, a TypeScript error is shown at a line where the function is defined. The error says: TS1055: Type 'Metadata | Promise ' is not a valid async function return type in ES5/ES3 because it does not refer to a Promise-compatible constructor value.

However, building the project works fine. Moreover, when opening the same project in Visual Studio Code, there are no errors at all.

WebStorm:

Visual Studio Code:

Expected Behavior

No TypeScript errors are shown when defining a valid generateMetadata function.

Which browser are you using? (if relevant)

No response

How are you deploying your application? (if relevant)

No response

_NEXT-665

[t3dotgg]

Confirming this isn't Webstorm specific, appears these typedefs are bad

https://github.com/vercel/next.js/pull/45723/files#r1121140364

[ijjk]

This should be fixed by #46596 which is now available in v13.3.3-canary.0

[github-actions]

This closed issue has been automatically locked because it had no new activity for a month. If you are running into a similar issue, please create a new issue with the steps to reproduce. Thank you.