Declaration TypeScript Bug in NextAuth v5

[SiebeBaree]

Environment

System:
OS: macOS 14.4.1
CPU: (8) arm64 Apple M1
Memory: 63.70 MB / 16.00 GB
Shell: 5.9 - /bin/zsh
Binaries:
Node: 21.7.1 - /opt/homebrew/bin/node
npm: 10.5.0 - /opt/homebrew/bin/npm
pnpm: 8.15.6 - /opt/homebrew/bin/pnpm
bun: 1.1.3 - ~/.bun/bin/bun
Watchman: 2024.03.25.00 - /opt/homebrew/bin/watchman
Browsers:
Brave Browser: 123.1.64.122
Chrome: 123.0.6312.123
Safari: 17.4.1
npmPackages:
next: 13.5.4 => 13.5.4
next-auth: ^5.0.0-beta.16 => 5.0.0-beta.16
react: ^18 => 18.2.0

Reproduction URL

https://github.com/SiebeBaree/declaration-ts-bug-next-auth-v5

Describe the issue

When turning on declararation and declarationMap in the tsconfig.json NextAuth v5 beta 16 will give the following error:

The inferred type of 'auth' cannot be named without a reference to '../node_modules/next-auth/lib'. This is likely not portable. A type annotation is necessary.

The code works perfectly fine in dev mode but will cause build errors during deployment.
The error happens in src/auth.ts in the reproduction repo linked above

How to reproduce

1. npx create-next-app@latest (enable TypeScript)
2. npm install next-auth@beta
3. Create the auth.ts file like the installation guide recommends
4. Set the declaration and declarationMap to true in the compilerOptions of your tsconfig.json

This repository uses Bun but this error is the same on npm, pnpm with node.js runtime.

Expected behavior

That even with declaration and declarationMap set to true NextAuth should give any issues when using the new auth() function.

[SiebeBaree]

@SiebeBaree same here. Did you find a workaround?

Yes, turn of declaration and declarationMap in your tsconfig