[v8] CJS interop factory shadowed when re-bundling rolldown-emitted CJS output

[williamlark]

Describe the bug

vite build silently generates broken code when bundling a CJS package whose files were themselves previously emitted by rolldown using "unbundle" mode.

The root cause is a naming collision: rolldown uses require_<filestem> as the variable name for its __commonJS factory wrappers. When a source file already contains a local variable with the same name (because it was previously emitted by rolldown), rolldown skips creating the outer factory, yet still replaces require("./file.cjs") with require_<X>() inside the wrapper body. The result is self-referencing code that crashes at runtime:

var require_greet = require_greet();  // require_greet is never defined — TypeError

Reproduction

https://github.com/williamlark/vite-rolldown-cjs-interop-collision

Steps to reproduce

Load the reproduction repo and pnpm install && pnpm build && pnpm preview

System Info

System:
    OS: macOS 26.3.1
    CPU: (12) arm64 Apple M3 Pro
    Memory: 88.06 MB / 18.00 GB
    Shell: 5.9 - /bin/zsh
  Binaries:
    Node: 22.22.2 - /[redacted]/.nvm/versions/node/v22.22.2/bin/node
    npm: 10.9.7 - /[redacted]/.nvm/versions/node/v22.22.2/bin/npm
    pnpm: 10.13.1 - /[redacted]/pnpm/pnpm
  Browsers:
    Chrome: 146.0.7680.178
    Edge: 146.0.3856.97
    Firefox: 149.0
    Safari: 26.3.1
  npmPackages:
    vite: ^8.0.5 => 8.0.5

Used Package Manager

pnpm

Logs

No response

Validations

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• The provided reproduction is a minimal reproducible example of the bug.

[vorobiovkirill]

Any ETA to fix ?