fix: use processModule as receiver when falling back in process polyfill (#541)

[guoyangzhen]

🔗 Linked issue

Closes #541

📝 Description

The process polyfill uses a Proxy to layer unenv's polyfill over the original process object. When a property doesn't exist on the proxy target, it falls back to processModule (unenv's polyfill implementation):

return Reflect.get(processModule, prop, receiver);

The problem: receiver is the Proxy wrapping the original process, not processModule. When processModule has getters that rely on private fields (like #stdout in the std implementations), Reflect.get invokes the getter with this = receiver — which is the wrong object and lacks the private fields.

This causes:

Uncaught TypeError: Cannot read private member #t from an object whose class did not declare it.

Fix

Pass processModule as the receiver instead of receiver:

- return Reflect.get(processModule, prop, receiver);
+ return Reflect.get(processModule, prop, processModule);

This ensures getters/methods on processModule are invoked with this = processModule, which has the expected private fields.

Credit

Solution identified by the issue reporter @unjs/unenv#541.

Summary by CodeRabbit

• Bug Fixes
  • Corrected the property access behavior in the process polyfill to ensure proper context binding when accessing properties.

[coderabbitai]

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: defaults

Review profile: CHILL

Plan: Pro

Run ID: 3e2705be-7311-4771-8508-3373b5d49dcf

📥 Commits

Reviewing files that changed from the base of the PR and between f89b7cc and 9e228a9.

📒 Files selected for processing (1)

• src/runtime/polyfill/process.ts

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📝 Walkthrough

Walkthrough

The process polyfill's proxy get trap fallback was updated to use processModule as the receiver in Reflect.get instead of the original proxy receiver, ensuring methods and getters in processModule maintain correct this context and access to private members.

Changes

Cohort / File(s)	Summary
Process Polyfill Context Binding Fix src/runtime/polyfill/process.ts	Changed Reflect.get third argument from receiver to processModule in proxy fallback to ensure private members and context-dependent properties are correctly bound when accessed through the proxy.

Estimated code review effort

🎯 1 (Trivial) | ⏱️ ~3 minutes

Poem

🐰 A proxy that bounced back the wrong frame,
Now processModule claims proper name,
With this context mended just right,
Private members shine in the light! ✨

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title accurately describes the main change: fixing the process polyfill by using processModule as the receiver in the Reflect.get fallback.
Linked Issues check	✅ Passed	The PR directly implements the proposed fix from issue #541: replacing Reflect.get(processModule, prop, receiver) with Reflect.get(processModule, prop, processModule) to resolve private field access errors.
Out of Scope Changes check	✅ Passed	The change is minimal and focused: only the receiver argument in one Reflect.get call is modified, directly addressing the reported bug without introducing unrelated modifications.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.

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✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests

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