PR #86480: fix(turbopack): correct __dirname and __filename in CJS modules

• Repository: vercel/next.js
• Author: WonderSTK
• State: open | merged: False
• Link: https://github.com/vercel/next.js/pull/86480

Description (problem / solution / changelog)

This commit fixes an issue where __dirname and __filename were not being correctly resolved in CommonJS modules when using Turbopack. The issue was that the origin of the requiring module was being used to resolve these variables, instead of the origin of the CJS module itself.

To fix this, I've introduced a new CjsPath variant to the FreeVarReference enum. This new variant is used to represent __dirname and __filename in CJS modules. The handle_free_var_reference function in urbopack/crates/turbopack-ecmascript/src/references/mod.rs has been updated to handle this new variant and resolve the path correctly using the origin of the CJS module.

This change ensures that __dirname and __filename have the correct values in CJS modules, which is important for compatibility with existing Node.js code.

Fixes #86476

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Changed files

• turbopack/crates/turbopack-core/src/compile_time_info.rs (modified, +9/-0)
• turbopack/crates/turbopack-ecmascript/src/references/mod.rs (modified, +29/-6)

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PR #9: Fix Vercel deployment and dev server issues

• Repository: House-Wolf/hw_website
• Author: NFGGamekiller
• State: closed | merged: True
• Link: https://github.com/House-Wolf/hw_website/pull/9

Description (problem / solution / changelog)

Summary

This PR fixes critical Vercel deployment failures and local development server issues related to Prisma, Turbopack, and pnpm configuration.

Issues Resolved

1. Vercel Build Failures ✅

• Fixed ERR_PNPM_OUTDATED_LOCKFILE by regenerating pnpm-lock.yaml
• Fixed Prisma generation failures during build
• Removed unnecessary prisma.config.ts that was requiring DATABASE_URL during build

2. Turbopack Workspace Root Detection ✅

• Fixed "Next.js inferred your workspace root, but it may not be correct" error
• Worked around Next.js 16.0.4 bug where __dirname resolves to /ROOT/... in Turbopack
• Removed conflicting package-lock.json that confused Turbopack's root detection
• Added proper outputFileTracingRoot and turbopack.root configuration

3. Prisma Module Resolution with pnpm ✅

• Fixed "Cannot find module .prisma/client/default" error
• Configured pnpm to use hoisted node-linker for proper module resolution
• Removed custom Prisma output path in favor of standard location

Changes Made

Configuration Files

• .npmrc (new): Configure pnpm to use hoisted node-linker for Prisma compatibility
• next.config.mjs (converted from .ts): Added Turbopack and Prisma configuration
  • Hardcoded projectRoot to work around Turbopack __dirname bug
  • Added serverExternalPackages for Prisma
  • Synced outputFileTracingRoot with turbopack.root
• vercel.json (new): Force Vercel to use custom build command
• package.json: Updated build script to run prisma generate && next build

Prisma Configuration

• prisma/schema.prisma: Removed custom output path
• lib/prisma.ts: Updated to import from standard @prisma/client
• Deleted prisma.config.ts: Unnecessary file causing build failures

Cleanup

• Removed conflicting package-lock.json (using pnpm exclusively)
• Removed old app/generated/prisma directory
• Cleared .next cache

Technical Details

Root Cause Analysis

1. Turbopack Bug: Next.js 16.0.4 has a known bug where __dirname resolves incorrectly in Turbopack (Issue #86476)
2. pnpm Isolation: pnpm's content-addressable store isolates dependencies, preventing Turbopack from finding .prisma/client at the expected location (Issue #25833)
3. Multiple Lockfiles: Having both npm and pnpm lockfiles confused Turbopack's workspace detection

Solutions Applied

1. Hardcoded absolute path in next.config.mjs as workaround for __dirname bug
2. Hoisted node-linker in .npmrc to make pnpm use flat structure like npm
3. Synchronized configuration between outputFileTracingRoot and turbopack.root (required per Next.js source code)

Testing

• ✅ Local dev server starts successfully with npm run dev
• ✅ Prisma client imports correctly
• ✅ Turbopack workspace root detection working
• ✅ All changes committed and pushed

Next Steps

Once merged:

1. Vercel deployment should succeed
2. When Next.js releases fix for __dirname bug, can replace hardcoded path with dynamic resolution

Related Issues & Documentation

• Turbopack __dirname bug
• Prisma with pnpm custom output
• Turbopack root configuration
• serverExternalPackages config

🤖 Generated with Claude Code

Changed files

• .npmrc (added, +1/-0)
• next.config.mjs (added, +25/-0)
• next.config.ts (removed, +0/-15)