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Reentrant structuredClone breaks outer circular references

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Assessment

Difficulty
3/5
Estimated time
1-2 days
Newbie friendliness
62/100
Issue type
Bug
Clarity
Mostly clear
Activity status
Active
Tech stack
javascript, react-native
Domain
mobile

Research direction

Start by locating the React Native structuredClone polyfill and its cycle-detection memory handling. Reproduce a nested clone from an enumerable getter with an outer circular reference, then verify that reentrant calls use independent memory while ordinary cloning retains its behavior.

Written by the indexing model from the issue text.

Description

Needs: Author Feedback Needs: Repro
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

Dominant language
C++
Stars
127k
Forks
25.3k
PR merge metrics
No merged PRs in 30d

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  4. Open a pull request that references the issue number.

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