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structuredClone coerces rejected values while creating DataCloneError #58220
Description
Description
The React Native structuredClone polyfill interpolates rejected values into its error message. That invokes user-defined coercion such as Symbol.toPrimitive; a non-cloneable function or WeakMap can therefore replace the required DataCloneError with an arbitrary user-thrown error.
Expected behavior
Rejecting an unsupported value should produce DOMException / DataCloneError without executing user coercion hooks. The non-standard message does not need to include the rejected value.
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 #58220 is labeled separately.
Verified using the native Hermes/Fabric Fantom runner on main
cd2de187e8878119896159371225acbb9dfa5d9c. The unsupported-value case still fails: coercion runs instead of producing the expected DataCloneError.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.