fix: return object from generated retain override

[rbudnar]

Summary

Generated Objective-C subclasses override retain with an IMP declared as a void-returning block even though the installed method is encoded @@: and retain must return the object. Make both the original IMP function pointer and replacement block return id.

Reproduction and verification

On an Intel/x86_64 macOS 15.7.9 host with Xcode 16.4 and an iOS 18.6 iPhone 16 Plus Simulator, a NativeScript 9.1.0 app crashed at -[UIApplication setDelegate:] before UI. LLDB showed the NativeScript-generated delegate's retain IMP returning an invalid object pointer. The same crash occurred in Debug and Release builds and in a clean base app unrelated to the feature being tested.

Rebuilding the 9.1.0 runtime with this three-line return-type correction allowed the installed app to launch. Its native Files picker then restored a 30,695,814-byte JSON backup (1,700 workout rows, 243 tombstones) and exported a 30,695,812-byte backup whose canonical data matched the input. This is simulator evidence from the 9.1.0 source; I have not run the upstream main test suite and cannot claim Apple Silicon or device verification.

Related: #292 reports an Intel simulator startup crash, though that issue does not include a matching stack trace.

Scope

This changes only the ABI declaration for the generated retain override. It does not alter retain-count policy or release behavior. PR #403 touches the same section and currently retains the void return signature; this change may need to be carried through that refactor.

Summary by CodeRabbit

• Bug Fixes
  • Improved runtime object-retention handling so retain operations preserve and return their expected result. Existing retain-count checks, garbage-collection protection, and release behavior are unchanged. This update does not add or remove user-facing functionality, but helps ensure object-retention operations continue to behave consistently within the runtime.

[coderabbitai]

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No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: Repository UI

Review profile: CHILL

Plan: Advanced

Run ID: 3678c84f-e0f4-4786-a623-d7ec8cf3dea8

📥 Commits

Reviewing files that changed from the base of the PR and between 1736146 and c3a56c9.

📒 Files selected for processing (1)

• NativeScript/runtime/ClassBuilder.mm

Included review availability: This review used your included allowance. Your plan provides up to 2 included reviews per hour; 1 remain after this review.

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📝 Walkthrough

Walkthrough

The retain override now stores the original retain implementation with an id return type and returns the result of forwarding the call.

Changes

Retain override

Layer / File(s)	Summary
Forward retain result NativeScript/runtime/ClassBuilder.mm	The saved retain function pointer now returns id. The replacement block returns the forwarded call’s result.

Priority: ➖ Normal

Estimated code review effort: 2 (Simple) | ~5 minutes

Change: Bug fix

Suggested reviewers: edusperoni

Merge Risk: ⚪ Minimal · up to c3a56

The override now returns the object produced by retain, matching the method contract. No concrete merge-blocking issue is evident in the supplied change context.

Architecture Summary

Architecture risk: 🔵 Low · up to c3a56

The change affects 1 system.

Changed systems: NativeScript

Architecture concerns
No architecture-level concerns identified.

Review details

Systems and components

• observed — NativeScript (service) was modified; 1 changed file maps to changed impact.

Before / after behavior

• observed — Modified behavior in NativeScript/runtime/ClassBuilder.mm: The retain function pointer changes its return type from void to id, matching the Objective-C retain method; the replacement block continues to forward to the original implementation and now returns its object result.

🚥 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 clearly and concisely describes the main change: returning the object from the generated retain override.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check. Docstring coverage is scoped to functions touched by this diff. Analyzed 0 functions across 0…
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.

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_{A rabbit checks the retain call,
Its object result comes back to all.
The pointer’s type is now id,
The forwarded value is returned with pride.
One small change, then off I hop,
Through clover fields, I gladly stop.}

_{Comment @coderabbitai help to get the list of available commands.}