Link to the code that reproduces this issue

https://github.com/dimak-dev/turbopack-local-module-symlink-bug

To Reproduce

1. Create a new Next.js project:

   npx create-next-app@latest  

2. Create or download an external module in a separate directory:

   npm init 

3. Add an exportable function to this module:

   export function foo() {
     return 'bar';
   }

4. Install the external module into the Next.js project as a symlink (not a hard copy):

   npm install <path_to_external_module> 

5. Import the foo() function into the Next.js project.

6. Run the Next.js development server with Turbopack enabled:

   next dev --turbo

OR

1. Clone this repository:

   git clone https://github.com/dimak-dev/turbopack-local-module-symlink-bug.git
   cd turbopack-local-module-symlink-bug

2. Navigate to the next.js directory:

   cd next.js

3. Start the Next.js development server using Turbopack:

   npm run dev:turbo

4. Observe the error indicating that Turbopack cannot resolve the internal-module (Build Error: Module not found: Can't resolve 'internal-module').

Current vs. Expected behavior

Expected Behavior: Turbopack should correctly resolve modules linked via symbolic links, even if those modules reside outside the project directory.

Current Behavior: Turbopack throws an error when attempting to resolve the internal-module if it is located outside the project directory.

Provide environment information

Operating System:
  Platform: darwin
  Arch: x64
  Version: Darwin Kernel Version 24.3.0: Thu Jan  2 20:22:00 PST 2025; root:xnu-11215.81.4~3/RELEASE_X86_64
  Available memory (MB): 16384
  Available CPU cores: 12
Binaries:
  Node: 22.13.1
  npm: 10.9.2
  Yarn: N/A
  pnpm: N/A
Relevant Packages:
  next: 15.2.4 // Latest available version is detected (15.2.4).
  eslint-config-next: N/A
  react: 19.0.0
  react-dom: 19.0.0
  typescript: 5.8.2
Next.js Config:
  output: N/A

Which area(s) are affected? (Select all that apply)

Turbopack

Which stage(s) are affected? (Select all that apply)

next dev (local)

Additional context

If the internal-module is located inside the project directory and also uses a symbolic link, the module is resolved correctly without errors.

Canary (15.3.0-canary.24) is also affected.