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Please add a test which covers this scenario. |
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@javache thanks, I added the test |
…oves When a view flattens in the same commit in which its parent unflattens, a child with a negative zIndex is sorted before the view that contains it. The final loop of calculateShadowViewMutationsFlattener then took it for a new or removed view, because the nested recursion matched it through a different ShadowViewNodePair. Skip candidates the recursion recorded in the sub-visited map. Also stop keeping a pointer to a loop-local copy in unvisitedRecursiveChildPairs. Fixes react#58647 Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
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Fixes #58647
Summary:
When a view flattens in the same commit in which its parent unflattens, and one of its children has a negative
zIndex, the differ creates that child again while it's still mounted, or deletes it even though it only moves.On iOS this crashes in
RCTComponentViewRegistry(Debug) or with a SIGSEGV inRCTMountingManager(Release). ThezIndexsorts the child before the view that contains it, and the nested recursion then matches it through a differentShadowViewNodePair, soinOtherTree()stayed false on the candidate.I made the final create/delete loop in
calculateShadowViewMutationsFlatteneralso skip candidates whose tag the recursion recorded in the sub-visited map. I also fixedunvisitedRecursiveChildPairsstoring a pointer to a loop-local copy.Changelog:
[GENERAL] [FIXED] - Fix the differ creating a mounted view again, or deleting a moved view, when a child with a negative
zIndexmoves in a nested flatten/unflattenTest Plan:
The reproducer from #58647 no longer crashes on iOS with React Native built from source with this change; without it, it crashes on the first swap.