Adding "paths" and "baseUrl" to tsconfig.json breaks module augmentations

[zomars]

Describe the bug
It seems like the declared next-auth.d.ts is overriding the initial next-auth types instead of augmenting them.

To Reproduce
Steps to reproduce the behavior:

1. pnpm dlx create-t3-app@next
2. Select all packages
3. See src/pages/api/auth/[...nextauth].ts file

Expected behavior

Having default next-auth types PLUS the augmented ones.

Screenshots

[nexxeln]

Unable to reproduce, works fine for me.

Have you tried restarting your TypeScript server?

[zomars]

@nexxeln it may be out of scope, but it seems this happens as soon as you add path aliases to the tsconfig.json (took them from this project btw):

[nexxeln]

Yup thats the issue, I added path aliases and am now getting a type error.

[zomars]

It seems like even with #255 adding both "paths" and "baseUrl" to tsconfig.json keeps messing up with the module augmentations.

[nexxeln]

It seems like even with #255 adding both "paths" and "baseUrl" to tsconfig.json keeps messing up with the module augmentations.

Yeah I'm not sure how to fix this, I'll open an issue in next-auth

[kroucher]

Some info for troubleshooting, when the next-auth.d.ts file is moved into any subdirectory, the types start working again.

Not sure if having a 'types' folder by default is too opinionated, but either way, the issue lies with the next-auth.d.ts file being in the root directory.

[JohnDaly]

I noticed that changing the filename of next-auth.d.ts to something else (e.g. custom-next-auth.d.ts) will clear the type errors as well

[nexxeln]

Thank you for sharing @JohnDaly @kroucher

I'll mention this in the next-auth issue too, not sure if they have a better solution.

[JohnDaly]

Looks like TypeScript resolves the next-auth import to the next-auth.d.ts file, and doesn't go looking for the types in node_modules. When the name is different, it is able to find the types.

Here's the output from running tsc --traceResolution:

With next-auth.d.ts

======== Resolving module 'next-auth' from '/my-t3-app/next-auth.d.ts'. ========
Explicitly specified module resolution kind: 'NodeJs'.
'baseUrl' option is set to '/my-t3-app', using this value to resolve non-relative module name 'next-auth'.
'paths' option is specified, looking for a pattern to match module name 'next-auth'.
'baseUrl' option is set to '/my-t3-app', using this value to resolve non-relative module name 'next-auth'.
Resolving module name 'next-auth' relative to base url '/my-t3-app' - '/my-t3-app/next-auth'.
Loading module as file / folder, candidate module location '/my-t3-app/next-auth', target file type 'TypeScript'.
File '/my-t3-app/next-auth.ts' does not exist.
File '/my-t3-app/next-auth.tsx' does not exist.
File '/my-t3-app/next-auth.d.ts' exist - use it as a name resolution result.
======== Module name 'next-auth' was successfully resolved to '/my-t3-app/next-auth.d.ts'. ========

With custom-next-auth.d.ts

======== Resolving module 'next-auth' from '/my-t3-app/custom-next-auth.d.ts'. ========
Explicitly specified module resolution kind: 'NodeJs'.
'baseUrl' option is set to '/my-t3-app', using this value to resolve non-relative module name 'next-auth'.
'paths' option is specified, looking for a pattern to match module name 'next-auth'.
'baseUrl' option is set to '/my-t3-app', using this value to resolve non-relative module name 'next-auth'.
Resolving module name 'next-auth' relative to base url '/my-t3-app' - '/my-t3-app/next-auth'.
Loading module as file / folder, candidate module location '/my-t3-app/next-auth', target file type 'TypeScript'.
File '/my-t3-app/next-auth.ts' does not exist.
File '/my-t3-app/next-auth.tsx' does not exist.
File '/my-t3-app/next-auth.d.ts' does not exist.
Directory '/my-t3-app/next-auth' does not exist, skipping all lookups in it.
Loading module 'next-auth' from 'node_modules' folder, target file type 'TypeScript'.
Found 'package.json' at '/my-t3-app/node_modules/next-auth/package.json'.
'package.json' does not have a 'typesVersions' field.
File '/my-t3-app/node_modules/next-auth.ts' does not exist.
File '/my-t3-app/node_modules/next-auth.tsx' does not exist.
File '/my-t3-app/node_modules/next-auth.d.ts' does not exist.
'package.json' does not have a 'typings' field.
'package.json' has 'types' field 'index.d.ts' that references '/my-t3-app/node_modules/next-auth/index.d.ts'.
File '/my-t3-app/node_modules/next-auth/index.d.ts' exist - use it as a name resolution result.
Resolving real path for '/my-t3-app/node_modules/next-auth/index.d.ts', result '/my-t3-app/node_modules/.pnpm/[email protected].../node_modules/next-auth/index.d.ts'.
======== Module name 'next-auth' was successfully resolved to '/my-t3-app/node_modules/.pnpm/[email protected].../node_modules/next-auth/index.d.ts' with Package ID 'next-auth/[email protected]'. ========

[juliusmarminge]

@nexxeln it may be out of scope, but it seems this happens as soon as you add path aliases to the tsconfig.json (took them from this project btw):

that is correct. seems like when adding aliasing it doesn't find the type definition or something clashes :/

stumbled upon this a while back (and also helped someone in discord with similar issue) and cut this issue (vercel/next.js#38571) for Next.js along with it.

The fix I had was just moving the file somewhere into src and then typescript found it. The problem then (as described in the issue) is that Next.js's typedefinition is in root and your others are in src(/types) which is not ideal imo.

They converted it to a discussion and since I haven't heard anything of it though...

[nexxeln]

@nexxeln it may be out of scope, but it seems this happens as soon as you add path aliases to the tsconfig.json (took them from this project btw):

that is correct. seems like when adding aliasing it doesn't find the type definition or something clashes :/

stumbled upon this a while back (and also helped someone in discord with similar issue) and cut this issue (vercel/next.js#38571) for Next.js along with it.

The fix I had was just moving the file somewhere into src and then typescript found it. The problem then (as described in the issue) is that Next.js's typedefinition is in root and your others are in src(/types) which is not ideal imo.

They converted it to a discussion and since I haven't heard anything of it though...

Makes sense, should we close and pin this then?

[zomars]

I think renaming to something like custom-next-auth.d.ts would be a sensible approach. It would make it explicit that we're augmenting a module instead of declaring an untyped one.