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Reentrant structuredClone breaks outer circular references #58204
Description
Description
The React Native structuredClone polyfill reuses one module-global memory map under the assumption that cloning does not invoke user code. Enumerable property getters do execute, however, and can call structuredClone recursively. The inner call's finally clears the outer clone's memory, so later circular references are cloned again instead of pointing to the outer result.
Expected behavior
Each reentrant clone should have independent cycle-detection memory, while ordinary non-reentrant calls may retain the existing reusable-map optimization.
React Native Version
0.87.1 and current main
Affected Platforms
JavaScript runtime - All
Activity
react-native-bot commentedon Aug 30, 2026
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Missing reproducer: We could not detect a reproducible example in your issue report. Reproducers are mandatory and we can accept only one of those as a valid reproducer:
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react-native-bot commentedon Sep 24, 2026
This issue is waiting for author's feedback since 24 days. Please provide the requested feedback or this will be closed in 7 days.
OskarEichler commentedon Oct 2, 2026
Added the requested runnable RNTester Playground in #58806. Open Playground and press Run reproducers; the result for #58204 is labeled separately.
Verified using the native Hermes/Fabric Fantom runner on main
cd2de187e8878119896159371225acbb9dfa5d9c. The reentrant structuredClone getter/cycle case still fails.This is a constructed example based on the source audit, not a claimed production incident. The PR includes the exact native verification driver and results.